Title of Invention	POWER UNIT FOR MOTORCYCLE
Abstract	A power unit for a motorcycle comprising an internal combustion engine having a crankshaft whose axis extends in the longitudinal direction of a vehicle body of said motorcycle, and a power transmitting device for transmitting power from said crankshaft to a rear wheel, said power unit being located at a lower portion of said vehicle body wherein: the axis of said crankshaft is positioned in the vicinity of a vehicle body center; the axis of a cylinder of said internal combustion engine extends from the axis of said crankshaft in orthogonal relationship thereto and is inclined with respect to said vehicle body center so as to be raised on one said of said vehicle body the axis of a center shaft of a transmission in said power transmitting device extends in the longitudinal direction of said vehicle body and is positioned above the axis of said crankshaft on the other side of said vehicle body; and the front end of said center shaft is positioned on the front side of the rear end of said crankshaft.

Title of Invention

POWER UNIT FOR MOTORCYCLE

Abstract

A power unit for a motorcycle comprising an internal combustion engine having a crankshaft whose axis extends in the longitudinal direction of a vehicle body of said motorcycle, and a power transmitting device for transmitting power from said crankshaft to a rear wheel, said power unit being located at a lower portion of said vehicle body wherein: the axis of said crankshaft is positioned in the vicinity of a vehicle body center; the axis of a cylinder of said internal combustion engine extends from the axis of said crankshaft in orthogonal relationship thereto and is inclined with respect to said vehicle body center so as to be raised on one said of said vehicle body the axis of a center shaft of a transmission in said power transmitting device extends in the longitudinal direction of said vehicle body and is positioned above the axis of said crankshaft on the other side of said vehicle body; and the front end of said center shaft is positioned on the front side of the rear end of said crankshaft.

Full Text	FORM 2 THE PATENTS ACT 1970 [39 OF 1970] PROVISIONAL/COMPLETE SPECIFICATION [See Section 10] POWER UNIT FOR MOTORCYCLE HONDA GIKEN KOGYO KABUSHIKI KAISHA, A Corporation of Japan, 1-1 Minamiaoyama 2-Chome Minato - Ku, Tokyo, Japan The following specification particularly describes the nature of the invention and the manner in which it is to be performed.:- GRANTED 8 MAY 2000 10-5-2005 [DETAILED DESCRIPTION OF THE INVENTION] [Field of the Invention] The present invention relates to a power unit mounted on a motorcycle, and more particularly to an arrangement of an internal combustion engine and a power transmitting device constituting a power unit located at a lower portion of a vehicle body. [Prior Art] In a conventional motorcycle, a power unit is located below a step floor of a vehicle body (see Japanese Patent Laid-open No. 60-92929). This power unit for the motorcycle includes a single-cylinder internal combustion engine having a crankshaft and a cylinder. The crankshaft is longitudinally arranged so that its axis extends in the longitudinal direction of the vehicle body, and. the cylinder horizontally extends in the lateral direction of the vehicle body. The power unit further includes a power transmitting device having a clutch, speed reduction gear, etc. for transmitting power from the internal combustion engine to a rear wheel. The power transmitting device has an output shaft coaxial with the crankshaft. [Problem to be Solved by the Invention] In the conventional power unit for the motorcycle mentioned above, a cylinder head of the internal combustion engine and a case of the power transmitting device horizontally project in substantially same amount to the right and left, respectively, with respect to the lateral center of the vehicle body. Accordingly, the bank angle of the vehicle body is limited, so that a large bank angle.cannot be ensured. Further, since the crankshaft of the internal combustion engine and the output shaft of the power transmitting device are coaxial, the length of the power unit along the longitudinal direction of the vehicle body is large. It is accordingly an object of the present invention to provide a power unit for a motorcycle which allows a large bank angle of a vehicle body and has a compact size. [Means of Solving the Problem and Effect of the Invention] In accordance with the invention as defined in claim 1, there is provided in a power unit for a motorcycle including an internal combustion engine having a crankshaft whose axis extends in the longitudinal direction of a vehicle body of the motorcycle, and a power transmitting device for transmitting power from the crankshaft to a rear wheel, the power unit being located at a lower portion of the vehicle body; the improvement wherein the axis of the crankshaft is positioned in the vicinity of a vehicle body center; the axis of a cylinder of the internal combustion, engine extends from the axis of the crankshaft in orthogonal relationship thereto and is inclined with respect to the vehicle body center so as to be raised on one side of the vehicle body; the axis of a center shaft of a transmission in the power transmitting device extends in the longitudinal direction of the vehicle body and is positioned above the axis of the crankshaft on the other side of the vehicle body; and the front end of the center shaft is positioned on the front side of the rear end of the crankshaft. As described above, the axis of the crankshaft extends in the longitudinal direction of the vehicle body and is positioned in the vicinity of the vehicle body center; the axis of the cylinder extends from the axis of the crankshaft in orthogonal relationship thereto and is inclined with respect to the vehicle body center so as to be raised on one side of the vehicle body; and the axis of the center shaft of the transmission in the power transmitting device extends in the longitudinal direction of the vehicle body and is positioned above the axis of the crankshaft on the other side of the vehicle body. Accordingly, the cylinder is inclined with respect to the vehicle body center so as to be raised on one side of the vehicle body, and the power transmitting device is inclined with respect to the vehicle body center so as to be raised on the other side of the vehicle body. As a result, in the motorcycle whose power unit is located at a lower portion of the vehicle body to lower the center of gravity of the vehicle body, the bank angle of the vehicle body can be enlarged. Furthermore, the front end of the center shaft of the transmission in the power transmitting device is positioned on the front side of the rear end of the crankshaft. Accordingly, the length of the power unit along the longitudinal direction of the vehicle body can be reduced, thereby making the power unit compact. In accordance with the invention as defined in claim 2 including the configuration of the power unit defined in claim 1, the power transmitting device has a shaft drive mechanism for driving an axle on which the rear wheel is mounted, and the axis of the crankshaft is positioned below the axis of a drive shaft of the shaft drive mechanism. With this configuration, the axis of the crankshaft is positioned below the axis of the drive shaft. Accordingly, the center of gravity of the power unit can be lowered, and the center of gravity of the vehicle body can accordingly be lowered, under the condition where a required height of the drive shaft for driving the axle on which the rear wheel is mounted is ensured. In this specification, the terms of "front, rear, right, and left mean the front, rear, right, and left sides on a vehicle body as viewed in a vehicle advancing . direction, respectively. Further, the term of "vehicle body center" means a vertical plane passing through the lateral center of each wheel mounted on the motorcycle. Further, the term of "in the vicinity of the vehicle body center" means in the range of the lateral width of. each wheel mounted on the motorcycle. Accordingly there is provided a power unit for a motorcycle comprising an internal combustion engine having a crankshaft whose axis extends in the longitudinal direction of a vehicle body of said motorcycle, and a power transmitting device for transmitting power from said crankshaft to a rear wheel, said, power unit being located at a lower portion of said vehicle body; wherein: the axis of said crankshaft is positioned -in the vicinity of a vehicle body center; the axis of a cylinder of said internal combustion engine extends from • the axis of said crankshaft in orthogonal relationship thereto and is inclined with respect to said vehicle body center so as to be raised on one said of said vehicle body; the axis of a center shaft of a transmission in said power transmitting device extends in the longitudinal direction of .said vehicle body and is positioned above the axis of said crankshaft on the other side of said vehicle body; and the front end of said center shaft is positioned on the front side of the rear end of said crankshaft. [BRIEF DESCRIPTION OF THE DRAWINGS] [FIG. 1] FIG. 1 is a left side view of a scooter type motorcycle on which a power unit according to a first preferred embodiment of the present invention is mounted. [FIG. 2] FIG. 2 is a cross section taken along the line II- II in FIG. 1, showing the meshing of gears in the cross section of a crankcase and a cylinder head. [FIG. 3] FIG. 3 is a cross section taken along the line III- III in FIG. 2. [FIG. 4] FIG. 4 is a view similar to FIG. 3, showing a power unit according to a second preferred embodiment of the present invention. [Preferred Embodiment] Some preferred embodiments of the present invention will now be described with reference to FIGS. 1 to 4. FIGS. 1 to 3 show a first preferred embodiment of the present invention, in which FIG. 1 is a left side view of a scooter type motorcycle 1 on which a power unit 7 according to the present invention is mounted. The motorcycle 1 has a main frame composed of a front frame 3 and a pair of right and left rear frames 4. The front frame 3 and the rear frames 4 are connected by bolts 2. A front suspension mechanism for suspending a front wheel 5 and a steering mechanism for steering the front wheel 5 are provided at a front portion of the front frame 3. The power unit 7 for driving a rear wheel 6 is provided behind front portions of the rear frames 4. A rear suspension mechanism for suspending the rear wheel 6 is provided at rear portions of the rear frames 4. A seat 8 is provided above the rear frames 4. The motorcycle 1 further includes a front fender 9, front cover 10, floor step 11, frame body cover 12, and rear fender 13 arranged in this order from the front side to the rear side of the vehicle body. A pair of side covers 14 are provided on the right and left sides of the floor step 11. A storage box 15 for storing a helmet or the like is provided inside the frame body cover 12 at a portion under the seat 8. The front suspension mechanism includes a swing arm 16 located on the right side of the front wheel 5 and vertically swingably supported to a pivot shaft mounted at a front lower portion of the front frame 3, and a shock absorber 17 having one end pivotably connected to the swing arm 16 and the other end pivotably connected to the front frame 3. An axle holder 19 is laterally swingably mounted through a kingpin 18 to a front end of the swing arm 16. The front wheel 5 is rotatably supported to an axle 20 mounted on the axle holder 19. The steering mechanism includes a handle post 22 rotatably supported to a head pipe 21 mounted on a front upper portion of the front frame 3, a steering arm 23 vertically swingably supported to a pivot shaft mounted at a lower end of the handle post 22, and a link 24 having one end pivotably connected to the steering arm 23 and the other end pivotably connected to an arm 19a of the axle holder 19. Thus, the steering mechanism and the front suspension mechanism are independent of each other, thereby improving the drivability. Although not shown in detail, a front portion of the power unit 7 is swingably supported to the right and left rear frames 4 by a pair of hanger bolts inserted through hanger holes 26 of a pair of brackets 25 mounted on the right and left rear frames 4 and through a pair of tubular bushings 46 (see FIG. 2) provided at a front end of a lower crankcase 42L of an internal combustion engine 30 and a front end of a cylinder head 43 to be hereinafter described. A rear portion of the power unit 7 is mounted through a shock absorber 27 to a rear portion of the left rear frame 4. Accordingly, the power unit 7 is allowed to vertically swing according to any irregularities on a road surface during running of the motorcycle 1. The power unit 7 is located at a lower portion of the vehicle body to set the center of gravity of the vehicle body at a lower position. That is, the axes of both the tubular bushings 46 are positioned slightly above the horizontal plane containing the axis C1 of a crankshaft 31 of the internal combustion engine 30 and below the upper surface of the step floor 11. Further, the upper end surface of the power unit 7 except a radiator 41 is positioned at substantially the same level as that of the upper surface of the step floor 11. The power unit 7 includes an internal combustion engine 30 and a power transmitting device 90 having a planetary gear transmission 91 and a final drive 110. The internal combustion engine 30 is a spark-ignition four cycle single-cylinder water-cooled internal combustion engine. An air cleaner 32 is located below the frame body cover 12, and a flexible air induction pipe 33 extends from the air cleaner 32. The air induction pipe 33 is connected to an upstream end of a throttle body 34 located on the right side of the vehicle body. An intake pipe 35 connected to an intake port of the cylinder head 43 is connected to a downstream end of the throttle body 34. A fuel injector 36 is mounted on the intake pipe 35. A fuel tank 37 is located below the step floor 11, and fuel is supplied from the fuel tank 37 to the fuel injector 36. An exhaust pipe 38 is connected to an exhaust port of the cylinder head 43. An exhaust muffler 39 is connected to the exhaust pipe 38 and is located on the right side of the vehicle body. A fan cover 40 is mounted on the front end of a crankcase 42. A cooling fan 58 is provided inside the fan cover 40, and a radiator 41 is located on the upper side of the crankcase 42 so that a cooling air from the cooling fan 58 strikes on the radiator 41. An output from the transmission 91 of the power transmitting device 90 is transmitted through a shaft drive mechanism including a drive shaft 111 of the final drive 110 to the axle of the rear wheel 6, thereby driving the rear wheel 6. The power unit 7 will now be described in more detail with reference to FIGS. 2 and 3. FIG. 2 is a cross section taken along the line II-II in FIG. 1, showing the meshing of gears in the cross section of the crankcase 42 and the cylinder head 43, and FIG. 3 is a cross section taken along the line III-III in FIG. 2. The internal combustion engine 30 is configured by sequentially stacking and assembling a crankcase 42, a cylinder head 43, and a cylinder head cover 44. The crankcase 42 is composed of upper and lower crankcases 42U and 42L joined together along a split plane A containing the axis CI of the crankshaft 31 and inclined with respect to the horizontal plane so as to be raised on the left side of the vehicle body. The upper crankcase 42U is integrally formed at its upper portion with a cylinder 45 having an axis C2 inclined with respect to the vehicle body center CO so as to be raised on the right side of the vehicle body. The cylinder head 43 is mounted on the upper end surface of the cylinder 45 as a mounting plane B inclined with respect to the vehicle body center CO so as to face the right side of the vehicle body. The upper and lower crankcases 42U and 42L serve also as a front part of a transmission case 92 covering the transmission 91 of the power transmitting device 90 for transmitting the power from the crankshaft 31 to the rear wheel 6. A tubular bushing 46 is provided on the outer surface of the lower crankcase 42L at its front left end portion. A hanger bolt (not shown) for supporting the power unit 7 to the bracket 25 of the left rear frame 4 is inserted through the tubular bushing 46. The tubular bushing 46 is composed of a cylindrical portion 46a formed integrally with the lower crankcase 42L, a cylindrical elastic tube 46b of rubber on the like whose outer circumferential surface is fixed to the inner circumferential surface of the cylindrical portion 46a, and a. cylindrical metallic tube 46c whose outer circumferential surface is fixed to the inner circumferential surface of the elastic tube 46b. The hanger bolt is inserted through the metallic tube 46c. Another tubular bushing 46 having the same structure as that of the tubular bushing 46 provided on the lower crankcase 42L is also provided on the outer surface of the cylinder head 43 at its front right end portion. [0023] The crankshaft 31 is rotatably supported through a pair of main bearings 49 and 50 to the crankcase 42. The crankshaft 31 is longitudinally arranged so that its axis C1 extends in the longitudinal direction of the vehicle body. Each of the main bearings 49 and 50 is held in a pair of semicylindrical recesses formed on the upper and lower crankcases 42U and 42L so as to be exposed to the split plane A. The axis C1 of the crankshaft 31 is contained in the split plane A. The lateral position of the. axis C1 of the crankshaft 31 is set in the vicinity of the vehicle body center CO on the left side thereof. However, the lateral position of the axis C1 of the crankshaft 31 may be suitably set in the vicinity of the vehicle body center CO so that the maximum bank angle of the vehicle body on the right side becomes substantially equal to that on the left side. A piston 47 is slidably fitted in a cylinder bore of the cylinder 45. A smaller end of a connecting rod 48 is pivotably connected to a piston pin of the piston 47, and a larger end of the connecting rod 48 is pivotably connected to a crankpin 31b of the crankshaft 31. Thus, the crankshaft 31 is rotationally driven by the reciprocating piston 47 through the connecting rod 48. Further, the crankshaft 31 is provided with a balance weight 31a opposite to the piston pin, thereby suppressing the generation of vibrations due to the reciprocation of the piston 47 and the connecting rod 48. The relation among the split plane A, the mounting plane B, and the axis C2,of the cylinder 45 will now be described in more detail In a reference plane perpendicular to the axis C1 of the crankshaft 31 and containing the axis C2 of the cylinder 45, the angle α formed between the line of intersection of the split plane A and the reference plane and a reference vertical line as a straight line extending vertically upward from the point of intersection of the axis C1 of the crankshaft 31 and the reference plane is set to an acute angle. Further, the angle β formed between the axis C2 of the cylinder 45 and the reference vertical line is also set to an acute angle. The two angles α and β are set substantially equal to each other. Further, the angle γ formed between the reference vertical line and the extension of the line of intersection of the mounting plane B and the reference plane, which angle Y is a corresponding angle to the angle α, is set smaller than the angle α . Accordingly, the angle formed between the line of intersection of the split plane A and the reference plane and the line of intersection of the vehicle body center CO and the reference plane is equal to the angle α ; the angle formed between the axis C2 of the cylinder 45 and the line of intersection of the vehicle body center CO and the reference plane is equal to the angle β ; and the angle formed between the line of intersection of the mounting plane B and the reference plane and the line of intersection of the vehicle body center CO and the reference plane is equal to the angle 7 . These angles α., β, and γ may be set to suitable values in consideration of the magnitude of a bank angle to be set, for example. Regarding the split plane A and the mounting plane B both inclined so as to be raised on the right side of the vehicle body, the angle of inclination of the mounting plane B with respect to the horizontal plane is set larger than that of the split plane A. The split plane A and the mounting plane B intersect each other at a position below the cylinder 45. The cylinder head 43 is formed with an intake port to which the intake pipe 35 is connected, an exhaust port to which the exhaust pipe 38 is connected, and a supercharging port to which a boost air induction pipe connected to a double-acting piston type supercharger 52 is connected. All of the intake port, the exhaust port, and the supercharging port communicate with a combustion chamber formed on the lower surface of the cylinder head 43. The fuel is injected from the fuel injector 36 toward the intake port, and the mixture of the fuel and the induction air is supplied into the combustion chamber. A spark plug 51 for igniting the fuel-air mixture is mounted in the cylinder head 43 so as to be exposed to the combustion chamber. Further, a supercharging cylinder 52a forming a housing of the supercharger 52 is engaged with a hole formed through rear end walls of the cylinder head 43 and the upper crankcase 42U. This hole is formed by a pair of semicylindrical recesses formed on the cylinder head 43 and the upper crankcase 42U at their rear ends so as to be exposed to the mounting plane B. A camshaft 53 having an axis C3 extending in the longitudinal direction of the vehicle body is rotatably supported through a pair of bearings 54 and 55 to the cylinder head 43 and the upper crankcase 42U. Each of the bearings 54 and 55 is held in a pair of semicylindrical recesses formed on the upper crankcase 42U and the cylinder head 43 so as to be exposed to the mounting plane B. The axis C3 of the camshaft 53 is contained in the mounting plane B. With this arrangement of the camshaft 53, the axial height of the cylinder 45 can be reduced as compared with an internal combustion engine in which a camshaft is supported to a cylinder head only, so that the lateral size of the power unit 7 can be reduced. As shown in FIG. 3, an AC generator 56 is provided on a front end portion of the crankshaft 31 on the front side of the main bearing 49 for the crankshaft 31. The AC generator 56 has a rotor 56a fixed to the crankshaft 31 by a nut 57 secured to a threaded portion formed at the front end of the crankshaft 31. A cooling fan 58 for feeding a cooling air to the radiator 41 is fixedly mounted to the rotor 56a of the AC generator 56 by bolts 59. [0031] On the other hand, a first drive gear 60 and a second drive gear 61 are mounted on a rear end portion of the crankshaft 31 on the rear side of the main bearing 50 for the crankshaft 31 so as to be arranged in this order toward the rear side and be rotated integrally with the crankshaft 31. Further, the rear end of the crankshaft 31 is formed with an axially extending hole aligned with the axis CI of the crankshaft 31, and a hollow drive shaft 62a of an oil pump 62 is engaged with this hole so as to be rotated integrally with the crankshaft 31. The oil pump 62 is of a trochoid type, and its housing is formed by utilizing joint surfaces of the upper and lower crankcases 42U and 42L and the transmission case 42. The oil pump 62 has a rotor 62b accommodated in this housing and rotationally driven by the drive shaft 62a. Oil stored in a bottom portion of the lower crankcase 42L is sucked by the oil pump 62 through a suction passage 63 formed in the transmission case 92, and the oil discharged from the oil pump 62 is supplied through oil passages and oil pipes provided in the crankcase 42 and the transmission case 92 to the camshaft 53, a center shaft 93 of the transmission 91, and bearing portions. Further, the oil is supplied through the inside of the oil pump drive shaft 62a to the main bearings 49 and 50 of the crankshaft 31 and a sliding portion between the crankpin 31b and the larger end of the connecting rod 48 . The first drive gear 60 meshes with a large gear 65 mounted on an idler shaft 64 so as to be rotated integrally therewith. The idler shaft 64 serves also as a balancer shaft to be hereinafter described, so that the number of teeth of the large gear 65 is set equal to the number of teeth of the first drive gear 60 to rotate the idler shaft 64 at the same speed as that of the crankshaft 31. The large gear 65 is integrally formed with a small gear 66 meshing with a cam gear 67. The cam gear 67 is provided so as to be rotated integrally with the camshaft 53, thereby rotationally driving the camshaft 53. With this arrangement of the above gear train consisting of the gears 60, 65, 66, and 67, the camshaft 53 is rotated one revolution by every two revolutions of the crankshaft 31. The cam gear 67 is splined with a supercharging crankshaft 52c for reciprocating a supercharging piston 52b of the supercharger 52 of a double-acting piston type. The camshaft 53 is formed with a hollow portion serving as an oil passage for supplying the oil to sliding portions of cams and rocker arms to be hereinafter described. An extended portion of the supercharging crankshaft 52c is press-fitted with the hollow portion at its one end on the supercharger 52 side. Accordingly, the camshaft 53 is rotated integrally with the supercharging crankshaft 52c. The camshaft 53 is provided with an intake cam, exhaust cam, and supercharging cam for respectively opening an intake valve 68, exhaust valve (not shown), and supercharging valve 69. The intake valve 68 is operated by a first intake rocker arm 70 abutting against the intake cam and swingably moved thereby, a rod 72 linked to the first intake rocker arm 70 and pulled down thereby, and a second intake rocker arm 71 linked to the rod 72 and swingably moved thereby, thus performing an opening operation of the intake valve 68. Like the intake valve 68, the exhaust valve is operated by a first exhaust rocker arm abutting against the exhaust cam and swingably moved thereby, a rod linked to the first exhaust rocker arm and pulled down thereby, and a second exhaust rocker arm linked to the rod and swingably moved thereby, thus performing an opening operation of the exhaust valve. The supercharging valve 69 is operated by a first supercharging rocker arm 73 abutting against the supercharging cam and swingably moved thereby, a rod 75 linked to the first supercharging rocker arm 73 and pushed up thereby, and a second supercharging rocker arm 74 linked to the rod 75 and swingably moved thereby, thus performing an opening operation of the supercharging valve 69. A rotating disk is mounted on a front end portion of the camshaft 53, and a rotational position sensor 76 for detecting a rotational position of the camshaft 53 is mounted on the cylinder head 43 in the vicinity of the rotating disk, thereby detecting an engine stroke condition required for fuel injection timing control in the internal combustion engine 30. The idler shaft 64 having an axis C4 extending in the longitudinal direction of the vehicle body has a stepped cylindrical shape. That is, the idler shaft 64 has a large-diameter portion 64a and a small-diameter portion 64b. The large-diameter portion 64a is rotatably supported by a bearing 77 held by the upper and lower crankcases 42U and 42L, and the small-diameter portion 64b is rotatably supported by a bearing 78 held by the upper and lower crankcases 42U and 42L. Like the main bearings 49 and 50 for the crankshaft 31, each of the bearings 77 and 78 is held in a pair of semicylindrical recesses formed on the upper and lower crankcases 42U and 42L so as to be exposed to the split plane A. The axis C4 of the idler shaft 64 is contained in the split plane A. Since the split plane A is inclined by the angle a with respect to the vehicle body center CO, the axis C4 of the idler shaft 64 is positioned below the axis CI of the crankshaft 31 and on the right side with respect to the vehicle body center CO. A magnet type cooling water pump 79 is provided in alignment with the idler shaft 64. The cooling water pump 79 has a housing 79a accommodated in the large-diameter portion 64a of the idler shaft 64 with a radial gap being defined between the inner circumferential surface of the large-diameter portion 64a and the outer circumferential surface of the housing 79a. A cover 79b is fluid-tightly mounted on the housing 79a, and a water induction pipe 80 extending from an outlet tank of the radiator 41 is connected to the cover 79b of the cooling water pump 79. Although not shown in detail, the cylinder 45 is formed with a discharge hole 81 communicating with a discharge portion of the cooling water pump 79 and also communicating with a cooling water jacket formed so as to surround the cylinder bore (see FIG. 2) . A pump chamber is defined by the housing 79a and the cover 79b. A rotating shaft 79c is provided in this pump chamber so as to axially extend therein. The rotating shaft 79c has one end rotatably supported to the top of the cover 79b and the other end rotatably supported to the bottom of the housing 79a. An impeller 79d having three vanes is fixedly mounted on the rotating shaft 79c so as to rotate integrally therewith. Permanent magnets 79e are mounted on a shaft portion of the impeller 79d so as to. be arranged along the circumFErential direction of the shaft portion. In the above-mentioned gap defined between the inner circumFErential surface of the large-diameter portion 64a of the idler shaft 64 and the outer circumferential surface of the housing 79a of the cooling water pump 79, permanent magnets 79f are mounted on the inner circumferential surface of the large-diameter portion 64a with a minute gap defined between the permanent magnets 79f and the housing 79a so as to be arranged along the circumferential direction of the large-diameter portion 64a. Thus, a magnetic coupling is formed between the permanent magnets 79f mounted on the large-diameter portion 64a of the idler shaft 64 and the permanent magnets 79e mounted on the shaft portion of the impeller 79d. The radiator 41 is located in a V-shaped space formed by the upper crankcase 42U and the cylinder head 43, and the laterally opposite ends of the radiator 41 are fixed to the upper crankcase 42U and the cylinder head 43. Accordingly, when the idler shaft 64 is rotated, the impeller 79d is rotated through the magnetic coupling to thereby boost the cooling water induced through the water induction pipe 80 into the pump chamber. The boosted water is then supplied through the discharge portion of the cooling water pump 79 and the discharge hole 81 of the upper crankcase 42U to the cooling water jacket. As shown in FIG. 2, the cooling water having cooled high-Temperature portions of the cylinder 45 and the cylinder head 43 is returned from a water outlet of the cylinder head 43 through a thermostat 82 to an inlet tank of the radiator 41. The water outlet of the cylinder head 43 is formed as a cylindrical projection, and its cylindrical projecting portion is inserted through the wall of a storing chamber 41a formed integrally with a side portion of the inlet tank of the radiator 41, and is exposed into the storing chamber 41a, thereby obtaining fluid communication between the water outlet of the cylinder head 43 and the inlet tank of the radiator 41. The thermostat 82 is mounted in a passage portion where the cylindrical projecting portion is inserted through the wall of the storing chamber 41a. As mentioned above, the radiator 41 is located in the V-shaped space formed by the upper crankcase 4243a r and the cylinder head 43, thereby effecting compactness of the power unit 7. Further, it is not necessary to use any piping such as a hose for connecting the water outlet of the cylinder head 43 and the inlet tank of the radiator 41, thereby increasing the degree of freedom of arrangement of peripheral parts. In addition, the cooling water passage between the cylinder head 43 and the radiator 41 can be easily connected. A cylindrical weight 83 partially formed with an opening is mounted on the outer circumferential surface of the large-diameter portion 64a of the idler shaft 64. The cylindrical weight 83 serves as a balancer for suppressing vibrations due to the rotation of the crankshaft 31 having the balance weight 31a and vibrations due to the reciprocation of the piston 47 and the connecting rod 48. Accordingly, the idler shaft 64 serves both as a drive shaft for driving the cooling water pump 79 and as a balancer shaft. Thus, the idler shaft 64 provided in a drive mechanism for driving the camshaft 53 is formed as a coaxial two-shaft type rotating shaft to thereby function both as a drive shaft for driving the cooling water pump 79 and as a balancer shaft. As a result, the cost can be reduced as compared with the case of providing rotating shafts having these functions in addition to the idler shaft 64. The camshaft 53 and the idler shaft 64 are located on the side where the split plane A and the mounting plane B intersect each other with respect to the axis C2 of the cylinder 45, that is, on the side where both planes A and B approach each other. With this arrangement of the camshaft 53 and the idler shaft 64, the idler shaft 64 supported on the split plane A and the camshaft 53 supported on the mounting plane B can be located close to each other. Accordingly, no intermediate shaft is required between the idler shaft 64 and the camshaft 53, but the idler shaft 64 and the camshaft 53 can be directly coupled by the smaller gear 66 and the cam gear 67. As a result, the axial height of the cylinder 45 can be reduced, thereby reducing the lateral size of the power unit 7 to make it compact. Further, the number of parts can be reduced because no intermediate shaft is required as mentioned above. Further, since the camshaft 53 and the idler shaft 64 are positioned below the cylinder 45 obliquely raised from the crankshaft 31 on the right side, the center of gravity of the power unit 7 can be lowered. Further, this close arrangement of the camshaft 53 and the idler shaft 64 as a coaxial two-shaft type rotating shaft having a plurality of functions results in an effective use of the small space interposed between the split plane A and the mounting plane B on one side of the cylinder 45, so that a large space having no rotating shafts can be formed on the other side of the cylinder 45, and the radiator 41 as one of the peripheral parts can be located in this large space as mentioned above. The planetary gear transmission 91 as a component of the power transmitting device 90 in the power unit 7 includes a center shaft 93, input gear 94, starting clutch 95, second-speed shift clutch 96, third-speed shift clutch 97, fourth-speed shift clutch 98, and output shaft 99. The center shaft 93 extending in the longitudinal direction of the vehicle body is a central shaft of the transmission 91. A front end portion of the center shaft 93 is engaged with a pair of semicylindrical recesses formed on the inner surfaces of the front end portions of the upper and lower crankcases 42U and 42L so as to be exposed to the split plane A, and a rear end portion of the center shaft 93 is inserted through a support hole of a case of the final drive 110 mounted on the rear end surface of the transmission case 92. The rear end of the center shaft 93 is covered with a rotation stop member 100 mounted on the case of the final drive 110, thereby preventing rotation of the center shaft 93. The axis C5 of the center shaft 93 is contained in the split plane A between the upper and lower crankcases 42U and 42L, and extends in the longitudinal direction of the vehicle body at a left upper position with respect to the axis C1 of the crankshaft 31 located in the vicinity of the vehicle body center CO. As a result, the power transmitting device 90 is located at a left upper position with respect to the axis CI of the crankshaft 31. In contrast, the axis C4 of the idler shaft 64 supported on the split plane A extends in the longitudinal direction of the vehicle body at a right lower position with respect to the axis CI of the crankshaft 31. As a result, the center shaft 93 of the transmission 91 and the idler shaft 64 are positioned on the opposite sides with respect to the crankshaft 31, thereby reducing the lateral size of the power unit 7 to make it compact as compared with the case of locating such two rotating shafts on one side of the crankshaft 31. Thus, the front end portion of the center shaft 93 is supported to the front end portions of the upper and lower crankcases 42U and 42L. Further, the front end portion of the center shaft 93 is positioned on the front side of the rear end portion of the crankshaft 31. Accordingly, the crankshaft 31 and the center shaft 93 can be arranged so as to be overlapped in the longitudinal direction of the vehicle body, so that the length of the power unit 7 along the longitudinal direction of the vehicle body can be reduced to thereby make the power unit 7 compact. The transmission 91 will now be described in more detail in connection with its operation. The second drive gear 61 of the crankshaft 31 meshes with the input gear 94. A flanged boss 101 is rotatably mounted on the center shaft 93 of the transmission 91, and the input gear 94 is mounted on a flange formed at an axially central portion of the flanged boss 101. An inner member 95a of the starting clutch 95 is mounted on a rear portion of the flanged boss 101 so as to be rotated together. A start driven gear 105 is mounted on a front portion of the flanged boss 101 through a one-way clutch 106. The start driven gear 105 meshes with a small gear 104 of an idler shaft . constituting a speed reduction mechanism of a starter motor. At starting, the rotation of the starter motor is transmitted through a pinion 102, a large gear 103 of the idler shaft, the small gear 104 of the idler shaft, the start driven gear 105, the one-way clutch 106, the input gear 94, and the second drive gear 61 to the crankshaft 31. The starting clutch 95 coaxial with the center shaft 93 has an inner member 95a, an outer member 95b, and a centrifugal weight 95c. When the rotational speed of the inner member 95a exceeds a given speed, the centrifugal weight 95c operates to connect the inner member 95a and the outer member 95b and thereby rotate them together, thus obtaining a completely engaged condition of the starting clutch 95. Each of the shift clutches 96, 97, and 98 has a planetary gear mechanism and a clutch mechanism. The outer member of the clutch mechanism is integrally connected with the internally toothed gear of the planetary gear mechanism, and the inner member of the clutch mechanism is integrally connected with a carrier for rotatably supporting the planetary gear of the planetary gear mechanism. The carrier has a centrifugal weight for integrating the outer member and the inner member of the clutch mechanism through a plurality of clutch plates when the rotating speed of the carrier becomes a given speed. The sun gear of the planetary gear mechanism is mounted on the center shaft 93 through a one-way clutch. The outer member 95b of the starting clutch 95 is integrally connected with the outer member 96a of the second-speed shift clutch 96, and the carrier 96b of the second-speed shift clutch 96 is integrally connected with the outer member 97a of the third-speed shift clutch 97. Similarly, the carrier of the third-speed shift clutch 97 is integrally connected with the outer member of the fourth-speed shift, clutch 98, and the carrier of the fourth-speed shift clutch 98 is integrally connected with the output shaft 99. Until reaching a given rotating speed where the clutch mechanism in the second-speed shift clutch 96 is operated to integrate the internally toothed gear serving also as the outer member 96a and the carrier 96b serving also as the inner member, the carrier 96b is rotated at a given reduction ratio because of the sun gear 96c kept unrotated by the one-way clutch 96d, so that the outer member 97a of the third-speed shift clutch 97 is rotated at a reduced speed. Similarly, the outer member of the fourth-speed shift clutch 98 is rotated at a given reduction ratio by the speed reducing operation of the third-speed shift clutch 97, and the output shaft 99 is rotated at a given reduction ratio by the speed reducing operation of the fourth-speed shift clutch 98, thereby obtaining a maximum reduction ratio. When the rotating speed of the carrier 96b in the second-speed shift clutch 96 reaches a given speed to operate the clutch mechanism and integrate the internally toothed gear and the carrier 96b, the second-speed shift clutch 96 is rotated as a unit without carrying out its speed reducing operation. Until the carrier in the third-speed shift clutch 97 reaches a given speed, the carrier is rotated at a given reduction ratio, and the outer member of the fourth-speed shift clutch 98 is rotated at a reduced speed. Further, the output shaft 99 is rotated at a given reduction ratio by the speed reducing operation of the fourth-speed shift clutch 98, thereby obtaining a smaller reduction ratio. Similarly, when the clutch mechanism in the third-speed shift clutch 97 is operated and the third-speed shift clutch 97 is rotated as a unit without carrying out its speed reducing operation, the output shaft 99 is rotated at a given reduction ratio by the speed reducing operation of the fourth-speed shift clutch 98, thereby obtaining a smaller reduction ratio. Further, when the fourth-speed shift clutch 98 is rotated as a unit without carrying out its speed reducing operation by the operation of the clutch mechanism, the inner member 95a of the starting clutch 95 is directly coupled to the output shaft 99, so that the output shaft 99 is rotated at the same speed as that of the inner member 95a. The above given rotating speeds have different values, which are suitably set in consideration of speed shift characteristics. The output from the transmission 91 operated above is transmitted to the rear wheel 6 by the shift drive mechanism. That is, an output gear 107 is mounted on the output shaft 99 of the transmission 91 so as to be rotated together. The output gear 107 meshes with a gear 112 fixed to the drive shaft,111 of the final drive 110. The drive shaft 111 is located nearer to the vehicle body center CO than the center shaft 93 and has an axis C6 extending in the longitudinal direction of the vehicle body. A rear end portion of the drive shaft 111 is formed with a bevel gear (not shown), and this bevel gear meshes with a driven bevel gear mounted on the axle of the rear wheel 6. In this manner, the rotation of the output shaft 99 is reduced in speed and transmitted to the rear wheel 6, thereby driving the rear wheel 6. The axis CI of the crankshaft 31 is located below the axis C6 of the drive shaft 111 set according to the size of the rear wheel 6, thereby lowering the center of gravity of the power unit 7 and accordingly lowering the center of gravity of the vehicle body (see FIG. 1) . Further, a rotational speed sensor 113 for detecting a rotational signal from the drive shaft 111 is mounted on the case of the final drive 110, so as to detect the rotating speed of the output shaft 99 of the transmission 91 for control of the internal combustion engine 30. This preferred embodiment can exhibit the following effects by the above-mentioned configuration. With respect to the axis CI of the crankshaft 31 extending in the longitudinal direction of the vehicle body and located in the vicinity of the vehicle body center CO, the axis C2 of the cylinder 45 is inclined so as to be raised on the right side, and. the axis C5 of the center shaft 93 of the planetary gear transmission 91 as a component of the power transmitting device 90 extends in parallel to the axis C1 at a left upper position with respect thereto. That is, the transmission 91 is,Inclined so as to be raised on the left side at substantially the same angle as the angle of inclination of the cylinder 45 with respect to the vehicle body center CO. As a result, the bank angle of the vehicle body can be enlarged in the motorcycle 1 having the power unit 7 located at a lower portion of the vehicle body to lower the center of gravity of the vehicle body. Furthermore, since the cylinder 45 and the transmission 91 are inclined at substantially the same angle, the lateral balance of the power unit 7 can be ensured. The front end of the center shaft 93 of the planetary gear transmission 91 is supported to the inner surfaces of the front end portions of the upper and lower crankcases 42U and 42L at a position on the front side of the rear end of the crankshaft 31. Accordingly, the length of the power unit 7 along the longitudinal direction of the vehicle body can be reduced to thereby make the power unit 7 compact. The axis C1 of the crankshaft 31 is located below the axis C6 of the drive shaft 111. Accordingly, the center of gravity of the power unit 7 can be lowered to thereby lower the center of gravity of the vehicle body under the condition where a required height of the drive shaft 111 for driving the axle on which the rear wheel 6 is mounted is ensured. The idler shaft 64 is mounted on the joint surfaces of the upper and lower crankcases 42U and 42L which surfaces form the split plane A, and the camshaft 53 is mounted on the joint surfaces of the cylinder 45 and the cylinder head 43 which surfaces form the mounting plane B. Accordingly, the mountability of the idler shaft 64 and the camshaft 53 can be improved. The camshaft 53 and the idler shaft 64 are located on the side where the split plane A and the mounting plane B intersect each other with respect to the axis C2 of the cylinder 45, that is, on the side where both planes A and B approach each other. With this arrangement of the camshaft 53 and the idler shaft 64, the idler shaft 64 supported on the split plane A and the camshaft 53 supported on the mounting plane B can be located close to each other. Accordingly, no intermediate shaft is required between the idler shaft 64 and the camshaft 53, but the idler shaft 64 and the camshaft 53 can be directly coupled by the smaller gear 66 and the cam gear 67. As a result, the axial height of the cylinder 45 can be reduced, thereby reducing the lateral size of the power unit 7 to make it compact. Further, the number of parts can be reduced because no intermediate shaft is required as mentioned above. Further, since the camshaft 53 and the idler shaft 64 are positioned below the cylinder 45 obliquely raised from the crankshaft 31 on the right side, the center of gravity of the power unit 7 can be lowered. Further, this close arrangement of the camshaft 53 and the idler shaft 64 as a coaxial two-shaft type rotating shaft having a plurality of functions results in an effective use of the small space interposed between the split plane A and the mounting plane B on one side of the cylinder 45, so that a large space.having no rotating shafts can be formed on the other side of the cylinder 45, and the radiator 41 as one of the peripheral parts can be located in this large space as mentioned above. A V-shaped space is formed by the upper crankcase 42U and the cylinder head 43, and the radiator 41 can be compactly located in this V-shaped space, thereby making the power unit 7 compact. The camshaft 53 is located on the mounting plane B between the cylinder 45 and the cylinder head 43, so that the height of the cylinder head 43 can be reduced. Additionally, the camshaft 53 is located in the small space interposed between the split plane A and the mounting plane B on one side of the cylinder 45 as mentioned above. Accordingly, the internal combustion engine 3 0 can be made compact. The center shaft 93 of the transmission 91 and the idler shaft 64 are located on the opposite sides of the crankshaft 31. Accordingly, as compared with the case of locating such two rotating shafts on one side of the crankshaft 31, the lateral size of the power unit 7 can be reduced to thereby make the power unit 7 compact. The idler shaft 64 provided in a drive mechanism for driving the camshaft 53 is formed as a coaxial two-shaft type rotating shaft to thereby function both as a drive shaft for driving the cooling water pump 79 and as a balancer shaft. As a result, the cost can be reduced as compared with the case of providing rotating shafts having these functions in addition to the idler shaft 64. FIG. 4 is a view similar to FIG. 3, showing a second preferred embodiment of the present invention. The second preferred embodiment is different from the first preferred embodiment in the structure of the.power transmitting device in the power unit 7. The structure of the other portion is basically the same as that of the first preferred embodiment, so the same parts are denoted by the same reference numerals and the detailed description thereof will be omitted herein. Reference numeral 120 denotes a power transmitting device in the second preferred embodiment. The power transmitting device 120 includes a hydraulic transmission 121 having swash plates. The transmission 121 includes an input gear 122, a fixed capacity type swash hydraulic pump 123, a variable capacity type swash hydraulic motor 124, and an output shaft 125. The output shaft 125 having an axis C7 extending in the longitudinal direction of the vehicle body is a center shaft of the transmission 121. A front end portion of the output shaft 125 is supported through a bearing 126 to the inner surfaces of the front end portions of the upper and lower crankcases 42U and 42L. The bearing 126 is fitted with a pair of semicylindrical recesses formed on the upper and lower crankcases 42U and 42L so as to be exposed to the split plane A. A rear end portion of the output shaft 125 is supported through a bearing 128 to a support shaft inserted in a hole formed through the rear end wall of a transmission case 127. Accordingly, the axis C7 of the output shaft 125 is contained in the split plane A between the upper and lower crankcases 42U and 42L. Since the front end portion of the output shaft 125 is supported to the front end portions of the upper and lower crankcases 42U and 42L, the front end of the output shaft 125 is positioned on the front side of the rear end of the crankshaft 31 in the longitudinal direction of the vehicle body. Accordingly, the crankshaft 31 and the output shaft 125 can be arranged so as to be overlapped in the longitudinal direction of the vehicle body, thereby reducing the length of the power unit 7 along the longitudinal direction of the vehicle body and accordingly making the power unit 7 compact. The second drive gear 61 mounted on the crankshaft 31 meshes with the input gear 122 formed integrally with a housing 123a of the hydraulic pump 123. A start driven gear 129 meshing with the small gear of the idler shaft constituting the speed reduction mechanism of the starter motor is mounted through a one-way clutch 130 to a front portion of the housing 123a. The rotation of the starter motor at starting is transmitted to the crankshaft 31 in the same manner as that in the first preferred embodiment The hydraulic pump 123 includes a swash plate 123c for driving a plurality of pistons 123b in the housing 123a- The swash plate 123c is tilted by the rotation of the housing 123a to thereby drive each piston 123b and generate a high hydraulic pressure. The hydraulic motor 124 includes a cylinder block 124a having a plurality of pistons 124b, and a swash plate 124c. The cylinder block 124a is integrally connected with the output shaft 125. The hydraulic pressure from the hydraulic pump 123 is controlled by a control valve and supplied to the hydraulic motor 124. Then, each piston 124b is driven by the hydraulic pressure supplied to come into abutment against the swash plate 124c. As a result, the cylinder block 124a is rotated to thereby integrally rotate the output shaft 125. The rotating speed of the output shaft 125 can be continuously varied by changing the angle of the swash plate 124c by means of an actuator. Further, the rotation of the output shaft 125 may be interrupted, that is, the transmission of the rotation of the input gear 122 to the output shaft 125 may be interrupted by the above control valve. An output gear 131 mounted on the output shaft 125 of the hydraulic transmission 121 meshes with a gear fixed to a drive shaft 141 of a final drive 140. The drive shaft 141 has an axis C8 extending in the longitudinal direction of the vehicle body. A rear end portion of the drive shaft 141 is formed with a bevel gear 141a. The bevel gear 141a meshes with a driven bevel gear 142 mounted on an axle 143 of the rear wheel 6. Thus, the rotation of the output shaft 125 is reduced in speed and transmitted to the axle 143, thereby driving the rear wheel 6. Like the first preferred embodiment, the axis C1 of the crankshaft 31 is located below the axis C8 of the drive shaft 141, thereby lowering the center of gravity of the power unit 7 and accordingly lowering the center of gravity of the vehicle body. A rotational speed sensor 144 for detecting a rotational signal from the drive shaft 141 is mounted on the case of the final drive 140, so as to detect the rotating speed of the output shaft 125 of the transmission 121 for control of the internal combustion engine 30 and the transmission 121. The second preferred embodiment can also exhibit the same effects as those of the first preferred embodiment. In addition, the power unit 7 in the second preferred embodiment can be made more compact than that in the first preferred embodiment, because the length of the hydraulic transmission 121 along the longitudinal direction is smaller than that of the planetary gear transmission 91 in the first preferred embodiment. While the center shaft 93 of the planetary gear transmission 91, the output shaft 125 of the hydraulic transmission 121, and the idler shaft 64 are supported on the split plane A between the upper and lower crankcases 42U and 42L in the first and second preferred embodiments, these shafts may be supported to the crankcase 42 at any positions other than on the split plane A. Similarly, the camshaft 53 may be supported to the cylinder head 43 only rather than on the mounting plane B. While the motorcycle 1 in each of the first and second preferred embodiments is of a scooter type, the motorcycle to which the present invention is applicable may be any type of motorcycle other than the scooter type. [Explanation of Reference Numerals] 1: motorcycle 2; bolt 3: front frame .4: rear frame 5: front wheel 6: tear wheel 7: power unit 8: seat 9: front fender 10; front cover 11: step floor 12: frame body cover 13: rear fender 14: side cover 15: storage box 16: swing arm 17: shock absorber 18: kingpin 19: axle holder 20: axle 21: head pipe 22: handle post 23: steering arm 24: link 25: bracket 26: hanger hole 27: shock absorber 30: internal combustion engine 31: crankshaft 32: air cleaner 33: air induction pipe 34: throttle body 35: intake pipe 36: fuel injector 37: fuel tank 38: exhaust pipe 39; exhaust muffler 40: fan cover 41: radiator 42: crankcase 43: cylinder head 44: cylinder head cover 45: cylinder 46: tubular bushing 47: piston 48: connecting rod 49, 50: main bearing 51: spark plug 52: supercharger 53: camshaft 54, 55: bearing 56: AC generator 57: nut 58: cooling fan 59: bolt 60, 61: drive gear 62: oil pump 63: suction passage 64: idler shaft 65, 66, 67: gear 68: intake valve 69: supercharging valve 70, 71: intake rocker arm 72: rod 73, 74: supercharging rocker arm 75: rod 76: rotational position sensor 77, 78: bearing 79: cooling water pump 80: water guide pipe 81: discharge hole 82: thermostat 83: weight 90: power transmitting device 91: planetary gear transmission 92: transmission case 93: center shaft 94: input gear 95: starting clutch 96, 97, 98: shift clutch 99: output shaft 100: rotation stop member 101: flanged boss 102: pinion 103, 104, 105: gear 106: one-way clutch 107: output gear 110: final drive 111: drive shaft 112: gear 113: rotational speed sensor 120: power transmitting device 121: hydraulic transmission 122: input gear 123: swash hydraulic pump 124: swash hydraulic motor 125: output shaft 126: bearing 127: transmission case 128: bearing 129: gear 130: one-way clutch 131: output gear 140: final drive 141: drive shaft 142: gear 143: axle 144: rotational speed sensor A: split plane B: mounting plane CO: vehicle body center C1 to C8: axis We Claim: 1. A power unit for a motorcycle comprising an internal combustion engine having a crankshaft whose axis extends in the longitudinal direction of a vehicle body of said motorcycle, and a power transmitting device for transmitting power from said crankshaft to a rear wheel, said power unit being located at a lower portion of said vehicle body wherein: the axis of said crankshaft is positioned in the vicinity of a vehicle body center; the axis of a cylinder of said internal combustion engine extends from the axis of said crankshaft in orthogonal relationship thereto and is inclined with respect to said vehicle body center so as to be raised on one said of said vehicle body the axis of a center shaft of a transmission in said power transmitting device extends in the longitudinal direction of said vehicle body and is positioned above the axis of said crankshaft on the other side of said vehicle body; and the front end of said center shaft is positioned on the front side of the rear end of said crankshaft. 2. A power unit for a motorcycle as claimed in claim 1, wherein said power transmitting device has a shaft drive mechanism for driving an axle on which said rear wheel is mounted, and the axis of said crankshaft is positioned below the axis of a drive shaft of said shaft drive mechanism. 3. A power unit for a motorcycle substantially as herein described with reference to the accompanying drawings. Dated this 8th day of May, 2000. (JAYANTA PAL) OF REMFRY& SAGAR ATTORNEY FOR THE APPLICANTS

Full Text

FORM 2
THE PATENTS ACT 1970
[39 OF 1970]
PROVISIONAL/COMPLETE SPECIFICATION
[See Section 10]
POWER UNIT FOR MOTORCYCLE

HONDA GIKEN KOGYO KABUSHIKI KAISHA, A Corporation of Japan, 1-1 Minamiaoyama 2-Chome Minato - Ku, Tokyo, Japan
The following specification particularly describes the nature of the invention and the manner in which it is to be performed.:-

GRANTED

8 MAY 2000
10-5-2005

[DETAILED DESCRIPTION OF THE INVENTION]
[Field of the Invention]
The present invention relates to a power unit mounted on a motorcycle, and more particularly to an arrangement of an internal combustion engine and a power transmitting device constituting a power unit located at a lower portion of a vehicle body.
[Prior Art]
In a conventional motorcycle, a power unit is located below a step floor of a vehicle body (see Japanese Patent Laid-open No. 60-92929).
This power unit for the motorcycle includes a single-cylinder internal combustion engine having a crankshaft and a cylinder. The crankshaft is

longitudinally arranged so that its axis extends in the longitudinal direction of the vehicle body, and. the cylinder horizontally extends in the lateral direction of the vehicle body. The power unit further includes a power transmitting device having a clutch, speed reduction gear, etc. for transmitting power from the internal combustion engine to a rear wheel. The power transmitting device has an output shaft coaxial with the crankshaft.
[Problem to be Solved by the Invention]
In the conventional power unit for the motorcycle mentioned above, a cylinder head of the internal combustion engine and a case of the power transmitting device horizontally project in substantially same amount to the right and left, respectively, with respect to the lateral center of the vehicle body. Accordingly, the bank angle of the vehicle body is limited, so that a large bank angle.cannot be ensured. Further, since the crankshaft of the internal combustion engine and the output shaft of the power transmitting device are coaxial, the length of the power unit along the longitudinal direction of the vehicle body is large.
It is accordingly an object of the present

invention to provide a power unit for a motorcycle which allows a large bank angle of a vehicle body and has a compact size.
[Means of Solving the Problem and Effect of the Invention]
In accordance with the invention as defined in claim 1, there is provided in a power unit for a motorcycle including an internal combustion engine having a crankshaft whose axis extends in the longitudinal direction of a vehicle body of the motorcycle, and a power transmitting device for transmitting power from the crankshaft to a rear wheel, the power unit being located at a lower portion of the vehicle body; the improvement wherein the axis of the crankshaft is positioned in the vicinity of a vehicle body center; the axis of a cylinder of the internal combustion, engine extends from the axis of the crankshaft in orthogonal relationship thereto and is inclined with respect to the vehicle body center so as to be raised on one side of the vehicle body; the axis of a center shaft of a transmission in the power transmitting device extends in the longitudinal direction of the vehicle body and is positioned above the axis of the crankshaft on the other side of the vehicle body; and

the front end of the center shaft is positioned on the front side of the rear end of the crankshaft.
As described above, the axis of the crankshaft extends in the longitudinal direction of the vehicle body and is positioned in the vicinity of the vehicle body center; the axis of the cylinder extends from the axis of the crankshaft in orthogonal relationship thereto and is inclined with respect to the vehicle body center so as to be raised on one side of the vehicle body; and the axis of the center shaft of the transmission in the power transmitting device extends in the longitudinal direction of the vehicle body and is positioned above the axis of the crankshaft on the other side of the vehicle body. Accordingly, the cylinder is inclined with respect to the vehicle body center so as to be raised on one side of the vehicle body, and the power transmitting device is inclined with respect to the vehicle body center so as to be raised on the other side of the vehicle body. As a result, in the motorcycle whose power unit is located at a lower portion of the vehicle body to lower the center of gravity of the vehicle body, the bank angle of the vehicle body can be enlarged.

Furthermore, the front end of the center shaft of the transmission in the power transmitting device is positioned on the front side of the rear end of the crankshaft. Accordingly, the length of the power unit along the longitudinal direction of the vehicle body can be reduced, thereby making the power unit compact.
In accordance with the invention as defined in claim 2 including the configuration of the power unit defined in claim 1, the power transmitting device has a shaft drive mechanism for driving an axle on which the rear wheel is mounted, and the axis of the crankshaft is positioned below the axis of a drive shaft of the shaft drive mechanism.
With this configuration, the axis of the crankshaft is positioned below the axis of the drive shaft. Accordingly, the center of gravity of the power unit can be lowered, and the center of gravity of the vehicle body can accordingly be lowered, under the condition where a required height of the drive shaft for driving the axle on which the rear wheel is mounted is ensured.
In this specification, the terms of "front, rear,

right, and left mean the front, rear, right, and left sides on a vehicle body as viewed in a vehicle advancing . direction, respectively. Further, the term of "vehicle body center" means a vertical plane passing through the lateral center of each wheel mounted on the motorcycle. Further, the term of "in the vicinity of the vehicle body center" means in the range of the lateral width of. each wheel mounted on the motorcycle.
Accordingly there is provided a power unit for a motorcycle comprising an internal combustion engine having a crankshaft whose axis extends in the longitudinal direction of a vehicle body of said motorcycle, and a power transmitting device for transmitting power from said crankshaft to a rear wheel, said, power unit being located at a lower portion of said vehicle body; wherein:
the axis of said crankshaft is positioned -in the vicinity of a vehicle body center;
the axis of a cylinder of said internal combustion engine extends from • the axis of said crankshaft in orthogonal relationship thereto and is inclined with respect to said vehicle body center so as to be raised on one said of said vehicle body;
the axis of a center shaft of a transmission in said power transmitting device extends in the longitudinal direction of .said vehicle body and is positioned above the axis of said crankshaft on the other side of said vehicle body; and
the front end of said center shaft is positioned on the front side of the rear end of said crankshaft.

[BRIEF DESCRIPTION OF THE DRAWINGS]
[FIG. 1]
FIG. 1 is a left side view of a scooter type motorcycle on which a power unit according to a first preferred embodiment of the present invention is mounted.
[FIG. 2]
FIG. 2 is a cross section taken along the line II-
II in FIG. 1, showing the meshing of gears in the cross
section of a crankcase and a cylinder head.
[FIG. 3]
FIG. 3 is a cross section taken along the line III-
III in FIG. 2.
[FIG. 4]
FIG. 4 is a view similar to FIG. 3, showing a power unit according to a second preferred embodiment of the present invention.

[Preferred Embodiment]
Some preferred embodiments of the present invention will now be described with reference to FIGS. 1 to 4. FIGS. 1 to 3 show a first preferred embodiment of the present invention, in which FIG. 1 is a left side view of a scooter type motorcycle 1 on which a power unit 7 according to the present invention is mounted. The motorcycle 1 has a main frame composed of a front frame 3 and a pair of right and left rear frames 4. The front frame 3 and the rear frames 4 are connected by bolts 2. A front suspension mechanism for suspending a front wheel 5 and a steering mechanism for steering the front wheel 5 are provided at a front portion of the front frame 3. The power unit 7 for driving a rear wheel 6 is provided behind front portions of the rear frames 4. A rear

suspension mechanism for suspending the rear wheel 6 is provided at rear portions of the rear frames 4. A seat 8 is provided above the rear frames 4.
The motorcycle 1 further includes a front fender 9, front cover 10, floor step 11, frame body cover 12, and rear fender 13 arranged in this order from the front side to the rear side of the vehicle body. A pair of side covers 14 are provided on the right and left sides of the floor step 11. A storage box 15 for storing a helmet or the like is provided inside the frame body cover 12 at a portion under the seat 8.
The front suspension mechanism includes a swing arm 16 located on the right side of the front wheel 5 and vertically swingably supported to a pivot shaft mounted at a front lower portion of the front frame 3, and a shock absorber 17 having one end pivotably connected to the swing arm 16 and the other end pivotably connected to the front frame 3. An axle holder 19 is laterally swingably mounted through a kingpin 18 to a front end of the swing arm 16. The front wheel 5 is rotatably supported to an axle 20 mounted on the axle holder 19.

The steering mechanism includes a handle post 22 rotatably supported to a head pipe 21 mounted on a front upper portion of the front frame 3, a steering arm 23 vertically swingably supported to a pivot shaft mounted at a lower end of the handle post 22, and a link 24 having one end pivotably connected to the steering arm 23 and the other end pivotably connected to an arm 19a of the axle holder 19. Thus, the steering mechanism and the front suspension mechanism are independent of each other, thereby improving the drivability.
Although not shown in detail, a front portion of the power unit 7 is swingably supported to the right and left rear frames 4 by a pair of hanger bolts inserted through hanger holes 26 of a pair of brackets 25 mounted on the right and left rear frames 4 and through a pair of tubular bushings 46 (see FIG. 2) provided at a front end of a lower crankcase 42L of an internal combustion engine 30 and a front end of a cylinder head 43 to be hereinafter described. A rear portion of the power unit 7 is mounted through a shock absorber 27 to a rear portion of the left rear frame 4. Accordingly, the power unit 7 is allowed to vertically swing according to any irregularities on a road surface during running of the

motorcycle 1.

The power unit 7 is located at a lower portion of the vehicle body to set the center of gravity of the vehicle body at a lower position. That is, the axes of both the tubular bushings 46 are positioned slightly above the horizontal plane containing the axis C1 of a crankshaft 31 of the internal combustion engine 30 and below the upper surface of the step floor 11. Further, the upper end surface of the power unit 7 except a radiator 41 is positioned at substantially the same level as that of the upper surface of the step floor 11.

The power unit 7 includes an internal combustion engine 30 and a power transmitting device 90 having a planetary gear transmission 91 and a final drive 110. The internal combustion engine 30 is a spark-ignition four cycle single-cylinder water-cooled internal combustion engine. An air cleaner 32 is located below the frame body cover 12, and a flexible air induction pipe 33 extends from the air cleaner 32. The air induction pipe 33 is connected to an upstream end of a throttle body 34 located on the right side of the vehicle body. An intake pipe 35 connected to an intake port of the cylinder head

43 is connected to a downstream end of the throttle body 34. A fuel injector 36 is mounted on the intake pipe 35. A fuel tank 37 is located below the step floor 11, and fuel is supplied from the fuel tank 37 to the fuel injector 36. An exhaust pipe 38 is connected to an exhaust port of the cylinder head 43. An exhaust muffler 39 is connected to the exhaust pipe 38 and is located on the right side of the vehicle body. A fan cover 40 is mounted on the front end of a crankcase 42. A cooling fan 58 is provided inside the fan cover 40, and a radiator 41 is located on the upper side of the crankcase 42 so that a cooling air from the cooling fan 58 strikes on the radiator 41.
An output from the transmission 91 of the power transmitting device 90 is transmitted through a shaft drive mechanism including a drive shaft 111 of the final drive 110 to the axle of the rear wheel 6, thereby driving the rear wheel 6.
The power unit 7 will now be described in more detail with reference to FIGS. 2 and 3. FIG. 2 is a cross section taken along the line II-II in FIG. 1, showing the meshing of gears in the cross section of the crankcase 42

and the cylinder head 43, and FIG. 3 is a cross section
taken along the line III-III in FIG. 2.

The internal combustion engine 30 is configured by sequentially stacking and assembling a crankcase 42, a cylinder head 43, and a cylinder head cover 44. The crankcase 42 is composed of upper and lower crankcases 42U and 42L joined together along a split plane A containing the axis CI of the crankshaft 31 and inclined with respect to the horizontal plane so as to be raised on the left side of the vehicle body. The upper crankcase 42U is integrally formed at its upper portion with a cylinder 45 having an axis C2 inclined with respect to the vehicle body center CO so as to be raised on the right side of the vehicle body. The cylinder head 43 is mounted on the upper end surface of the cylinder 45 as a mounting plane B inclined with respect to the vehicle body center CO so as to face the right side of the vehicle body.
The upper and lower crankcases 42U and 42L serve also as a front part of a transmission case 92 covering the transmission 91 of the power transmitting device 90 for transmitting the power from the crankshaft 31 to the

rear wheel 6. A tubular bushing 46 is provided on the outer surface of the lower crankcase 42L at its front left end portion. A hanger bolt (not shown) for supporting the power unit 7 to the bracket 25 of the left rear frame 4 is inserted through the tubular bushing 46. The tubular bushing 46 is composed of a cylindrical portion 46a formed integrally with the lower crankcase 42L, a cylindrical elastic tube 46b of rubber on the like whose outer circumferential surface is fixed to the inner circumferential surface of the cylindrical portion 46a, and a. cylindrical metallic tube 46c whose outer circumferential surface is fixed to the inner circumferential surface of the elastic tube 46b. The hanger bolt is inserted through the metallic tube 46c. Another tubular bushing 46 having the same structure as that of the tubular bushing 46 provided on the lower crankcase 42L is also provided on the outer surface of the cylinder head 43 at its front right end portion. [0023]
The crankshaft 31 is rotatably supported through a pair of main bearings 49 and 50 to the crankcase 42. The crankshaft 31 is longitudinally arranged so that its axis C1 extends in the longitudinal direction of the vehicle body. Each of the main bearings 49 and 50 is held in a

pair of semicylindrical recesses formed on the upper and lower crankcases 42U and 42L so as to be exposed to the split plane A. The axis C1 of the crankshaft 31 is contained in the split plane A. The lateral position of the. axis C1 of the crankshaft 31 is set in the vicinity of the vehicle body center CO on the left side thereof. However, the lateral position of the axis C1 of the crankshaft 31 may be suitably set in the vicinity of the vehicle body center CO so that the maximum bank angle of the vehicle body on the right side becomes substantially equal to that on the left side.
A piston 47 is slidably fitted in a cylinder bore of the cylinder 45. A smaller end of a connecting rod 48 is pivotably connected to a piston pin of the piston 47, and a larger end of the connecting rod 48 is pivotably connected to a crankpin 31b of the crankshaft 31. Thus, the crankshaft 31 is rotationally driven by the reciprocating piston 47 through the connecting rod 48. Further, the crankshaft 31 is provided with a balance weight 31a opposite to the piston pin, thereby suppressing the generation of vibrations due to the reciprocation of the piston 47 and the connecting rod 48.

The relation among the split plane A, the mounting plane B, and the axis C2,of the cylinder 45 will now be described in more detail In a reference plane perpendicular to the axis C1 of the crankshaft 31 and containing the axis C2 of the cylinder 45, the angle α formed between the line of intersection of the split plane A and the reference plane and a reference vertical line as a straight line extending vertically upward from the point of intersection of the axis C1 of the crankshaft 31 and the reference plane is set to an acute angle. Further, the angle β formed between the axis C2 of the cylinder 45 and the reference vertical line is also set to an acute angle. The two angles α and β are set substantially equal to each other. Further, the angle
γ formed between the reference vertical line and the extension of the line of intersection of the mounting plane B and the reference plane, which angle Y is a corresponding angle to the angle α, is set smaller than the angle α . Accordingly, the angle formed between the line of intersection of the split plane A and the reference plane and the line of intersection of the vehicle body center CO and the reference plane is equal to the angle α ; the angle formed between the axis C2 of the cylinder 45 and the line of intersection of the

vehicle body center CO and the reference plane is equal to the angle β ; and the angle formed between the line of intersection of the mounting plane B and the reference plane and the line of intersection of the vehicle body center CO and the reference plane is equal to the angle 7 . These angles α., β, and γ may be set to suitable values in consideration of the magnitude of a bank angle to be set, for example.
Regarding the split plane A and the mounting plane B both inclined so as to be raised on the right side of the vehicle body, the angle of inclination of the mounting plane B with respect to the horizontal plane is set larger than that of the split plane A. The split plane A and the mounting plane B intersect each other at a position below the cylinder 45.
The cylinder head 43 is formed with an intake port to which the intake pipe 35 is connected, an exhaust port to which the exhaust pipe 38 is connected, and a supercharging port to which a boost air induction pipe connected to a double-acting piston type supercharger 52 is connected. All of the intake port, the exhaust port, and the supercharging port communicate with a combustion

chamber formed on the lower surface of the cylinder head 43. The fuel is injected from the fuel injector 36 toward the intake port, and the mixture of the fuel and the induction air is supplied into the combustion chamber. A spark plug 51 for igniting the fuel-air mixture is mounted in the cylinder head 43 so as to be exposed to the combustion chamber.
Further, a supercharging cylinder 52a forming a housing of the supercharger 52 is engaged with a hole formed through rear end walls of the cylinder head 43 and the upper crankcase 42U. This hole is formed by a pair of semicylindrical recesses formed on the cylinder head 43 and the upper crankcase 42U at their rear ends so as to be exposed to the mounting plane B.
A camshaft 53 having an axis C3 extending in the longitudinal direction of the vehicle body is rotatably supported through a pair of bearings 54 and 55 to the cylinder head 43 and the upper crankcase 42U. Each of the bearings 54 and 55 is held in a pair of semicylindrical recesses formed on the upper crankcase 42U and the cylinder head 43 so as to be exposed to the mounting plane B. The axis C3 of the camshaft 53 is contained in

the mounting plane B. With this arrangement of the camshaft 53, the axial height of the cylinder 45 can be reduced as compared with an internal combustion engine in which a camshaft is supported to a cylinder head only, so that the lateral size of the power unit 7 can be reduced.
As shown in FIG. 3, an AC generator 56 is provided on a front end portion of the crankshaft 31 on the front side of the main bearing 49 for the crankshaft 31. The AC generator 56 has a rotor 56a fixed to the crankshaft 31 by a nut 57 secured to a threaded portion formed at the front end of the crankshaft 31. A cooling fan 58 for feeding a cooling air to the radiator 41 is fixedly mounted to the rotor 56a of the AC generator 56 by bolts 59. [0031]
On the other hand, a first drive gear 60 and a second drive gear 61 are mounted on a rear end portion of the crankshaft 31 on the rear side of the main bearing 50 for the crankshaft 31 so as to be arranged in this order toward the rear side and be rotated integrally with the crankshaft 31. Further, the rear end of the crankshaft 31 is formed with an axially extending hole aligned with the axis CI of the crankshaft 31, and a hollow drive shaft

62a of an oil pump 62 is engaged with this hole so as to be rotated integrally with the crankshaft 31. The oil pump 62 is of a trochoid type, and its housing is formed by utilizing joint surfaces of the upper and lower crankcases 42U and 42L and the transmission case 42. The oil pump 62 has a rotor 62b accommodated in this housing and rotationally driven by the drive shaft 62a.
Oil stored in a bottom portion of the lower crankcase 42L is sucked by the oil pump 62 through a suction passage 63 formed in the transmission case 92, and the oil discharged from the oil pump 62 is supplied through oil passages and oil pipes provided in the crankcase 42 and the transmission case 92 to the camshaft 53, a center shaft 93 of the transmission 91, and bearing portions. Further, the oil is supplied through the inside of the oil pump drive shaft 62a to the main bearings 49 and 50 of the crankshaft 31 and a sliding portion between the crankpin 31b and the larger end of the connecting rod 48 .
The first drive gear 60 meshes with a large gear 65 mounted on an idler shaft 64 so as to be rotated integrally therewith. The idler shaft 64 serves also as a

balancer shaft to be hereinafter described, so that the number of teeth of the large gear 65 is set equal to the number of teeth of the first drive gear 60 to rotate the idler shaft 64 at the same speed as that of the crankshaft 31. The large gear 65 is integrally formed with a small gear 66 meshing with a cam gear 67. The cam gear 67 is provided so as to be rotated integrally with the camshaft 53, thereby rotationally driving the camshaft 53. With this arrangement of the above gear train consisting of the gears 60, 65, 66, and 67, the camshaft 53 is rotated one revolution by every two revolutions of the crankshaft 31.
The cam gear 67 is splined with a supercharging crankshaft 52c for reciprocating a supercharging piston 52b of the supercharger 52 of a double-acting piston type. The camshaft 53 is formed with a hollow portion serving as an oil passage for supplying the oil to sliding portions of cams and rocker arms to be hereinafter described. An extended portion of the supercharging crankshaft 52c is press-fitted with the hollow portion at its one end on the supercharger 52 side. Accordingly, the camshaft 53 is rotated integrally with the supercharging crankshaft 52c.

The camshaft 53 is provided with an intake cam, exhaust cam, and supercharging cam for respectively opening an intake valve 68, exhaust valve (not shown), and supercharging valve 69. The intake valve 68 is operated by a first intake rocker arm 70 abutting against the intake cam and swingably moved thereby, a rod 72 linked to the first intake rocker arm 70 and pulled down thereby, and a second intake rocker arm 71 linked to the rod 72 and swingably moved thereby, thus performing an opening operation of the intake valve 68. Like the intake valve 68, the exhaust valve is operated by a first exhaust rocker arm abutting against the exhaust cam and swingably moved thereby, a rod linked to the first exhaust rocker arm and pulled down thereby, and a second exhaust rocker arm linked to the rod and swingably moved thereby, thus performing an opening operation of the exhaust valve. The supercharging valve 69 is operated by a first supercharging rocker arm 73 abutting against the supercharging cam and swingably moved thereby, a rod 75 linked to the first supercharging rocker arm 73 and pushed up thereby, and a second supercharging rocker arm 74 linked to the rod 75 and swingably moved thereby, thus performing an opening operation of the supercharging

valve 69.

A rotating disk is mounted on a front end portion of the camshaft 53, and a rotational position sensor 76 for detecting a rotational position of the camshaft 53 is mounted on the cylinder head 43 in the vicinity of the rotating disk, thereby detecting an engine stroke condition required for fuel injection timing control in the internal combustion engine 30.
The idler shaft 64 having an axis C4 extending in the longitudinal direction of the vehicle body has a stepped cylindrical shape. That is, the idler shaft 64 has a large-diameter portion 64a and a small-diameter portion 64b. The large-diameter portion 64a is rotatably supported by a bearing 77 held by the upper and lower crankcases 42U and 42L, and the small-diameter portion 64b is rotatably supported by a bearing 78 held by the upper and lower crankcases 42U and 42L. Like the main bearings 49 and 50 for the crankshaft 31, each of the bearings 77 and 78 is held in a pair of semicylindrical recesses formed on the upper and lower crankcases 42U and 42L so as to be exposed to the split plane A. The axis C4 of the idler shaft 64 is contained in the split plane A.

Since the split plane A is inclined by the angle a with respect to the vehicle body center CO, the axis C4 of the idler shaft 64 is positioned below the axis CI of the crankshaft 31 and on the right side with respect to the vehicle body center CO.
A magnet type cooling water pump 79 is provided in alignment with the idler shaft 64. The cooling water pump 79 has a housing 79a accommodated in the large-diameter portion 64a of the idler shaft 64 with a radial gap being defined between the inner circumferential surface of the large-diameter portion 64a and the outer circumferential surface of the housing 79a. A cover 79b is fluid-tightly mounted on the housing 79a, and a water induction pipe 80 extending from an outlet tank of the radiator 41 is connected to the cover 79b of the cooling water pump 79. Although not shown in detail, the cylinder 45 is formed with a discharge hole 81 communicating with a discharge portion of the cooling water pump 79 and also communicating with a cooling water jacket formed so as to surround the cylinder bore (see FIG. 2) .
A pump chamber is defined by the housing 79a and the cover 79b. A rotating shaft 79c is provided in this

pump chamber so as to axially extend therein. The rotating shaft 79c has one end rotatably supported to the top of the cover 79b and the other end rotatably supported to the bottom of the housing 79a. An impeller 79d having three vanes is fixedly mounted on the rotating shaft 79c so as to rotate integrally therewith. Permanent magnets 79e are mounted on a shaft portion of the impeller 79d so as to. be arranged along the circumFErential direction of the shaft portion. In the above-mentioned gap defined between the inner circumFErential surface of the large-diameter portion 64a of the idler shaft 64 and the outer circumferential surface of the housing 79a of the cooling water pump 79, permanent magnets 79f are mounted on the inner circumferential surface of the large-diameter portion 64a with a minute gap defined between the permanent magnets 79f and the housing 79a so as to be arranged along the circumferential direction of the large-diameter portion 64a. Thus, a magnetic coupling is formed between the permanent magnets 79f mounted on the large-diameter portion 64a of the idler shaft 64 and the permanent magnets 79e mounted on the shaft portion of the impeller 79d.

The radiator 41 is located in a V-shaped space formed by the upper crankcase 42U and the cylinder head 43, and the laterally opposite ends of the radiator 41 are fixed to the upper crankcase 42U and the cylinder head 43.
Accordingly, when the idler shaft 64 is rotated, the impeller 79d is rotated through the magnetic coupling to thereby boost the cooling water induced through the water induction pipe 80 into the pump chamber. The boosted water is then supplied through the discharge portion of the cooling water pump 79 and the discharge hole 81 of the upper crankcase 42U to the cooling water jacket.
As shown in FIG. 2, the cooling water having cooled high-Temperature portions of the cylinder 45 and the cylinder head 43 is returned from a water outlet of the cylinder head 43 through a thermostat 82 to an inlet tank of the radiator 41. The water outlet of the cylinder head 43 is formed as a cylindrical projection, and its cylindrical projecting portion is inserted through the wall of a storing chamber 41a formed integrally with a side portion of the inlet tank of the radiator 41, and is

exposed into the storing chamber 41a, thereby obtaining fluid communication between the water outlet of the cylinder head 43 and the inlet tank of the radiator 41. The thermostat 82 is mounted in a passage portion where the cylindrical projecting portion is inserted through the wall of the storing chamber 41a.
As mentioned above, the radiator 41 is located in the V-shaped space formed by the upper crankcase 4243a
r
and the cylinder head 43, thereby effecting compactness of the power unit 7. Further, it is not necessary to use any piping such as a hose for connecting the water outlet of the cylinder head 43 and the inlet tank of the radiator 41, thereby increasing the degree of freedom of arrangement of peripheral parts. In addition, the cooling water passage between the cylinder head 43 and the radiator 41 can be easily connected.
A cylindrical weight 83 partially formed with an opening is mounted on the outer circumferential surface of the large-diameter portion 64a of the idler shaft 64. The cylindrical weight 83 serves as a balancer for suppressing vibrations due to the rotation of the crankshaft 31 having the balance weight 31a and

vibrations due to the reciprocation of the piston 47 and
the connecting rod 48.

Accordingly, the idler shaft 64 serves both as a drive shaft for driving the cooling water pump 79 and as a balancer shaft. Thus, the idler shaft 64 provided in a drive mechanism for driving the camshaft 53 is formed as a coaxial two-shaft type rotating shaft to thereby function both as a drive shaft for driving the cooling water pump 79 and as a balancer shaft. As a result, the cost can be reduced as compared with the case of providing rotating shafts having these functions in addition to the idler shaft 64.
The camshaft 53 and the idler shaft 64 are located on the side where the split plane A and the mounting plane B intersect each other with respect to the axis C2 of the cylinder 45, that is, on the side where both planes A and B approach each other. With this arrangement of the camshaft 53 and the idler shaft 64, the idler shaft 64 supported on the split plane A and the camshaft 53 supported on the mounting plane B can be located close to each other. Accordingly, no intermediate shaft is required between the idler shaft 64 and the camshaft 53,

but the idler shaft 64 and the camshaft 53 can be directly coupled by the smaller gear 66 and the cam gear 67. As a result, the axial height of the cylinder 45 can be reduced, thereby reducing the lateral size of the power unit 7 to make it compact. Further, the number of parts can be reduced because no intermediate shaft is required as mentioned above.
Further, since the camshaft 53 and the idler shaft 64 are positioned below the cylinder 45 obliquely raised from the crankshaft 31 on the right side, the center of gravity of the power unit 7 can be lowered.
Further, this close arrangement of the camshaft 53 and the idler shaft 64 as a coaxial two-shaft type rotating shaft having a plurality of functions results in an effective use of the small space interposed between the split plane A and the mounting plane B on one side of the cylinder 45, so that a large space having no rotating shafts can be formed on the other side of the cylinder 45, and the radiator 41 as one of the peripheral parts can be located in this large space as mentioned above.

The planetary gear transmission 91 as a component

of the power transmitting device 90 in the power unit 7 includes a center shaft 93, input gear 94, starting clutch 95, second-speed shift clutch 96, third-speed shift clutch 97, fourth-speed shift clutch 98, and output shaft 99. The center shaft 93 extending in the longitudinal direction of the vehicle body is a central shaft of the transmission 91. A front end portion of the center shaft 93 is engaged with a pair of semicylindrical recesses formed on the inner surfaces of the front end portions of the upper and lower crankcases 42U and 42L so as to be exposed to the split plane A, and a rear end portion of the center shaft 93 is inserted through a support hole of a case of the final drive 110 mounted on the rear end surface of the transmission case 92. The rear end of the center shaft 93 is covered with a rotation stop member 100 mounted on the case of the final drive 110, thereby preventing rotation of the center shaft 93.
The axis C5 of the center shaft 93 is contained in the split plane A between the upper and lower crankcases 42U and 42L, and extends in the longitudinal direction of the vehicle body at a left upper position with respect to the axis C1 of the crankshaft 31 located in the vicinity

of the vehicle body center CO. As a result, the power transmitting device 90 is located at a left upper position with respect to the axis CI of the crankshaft 31.

In contrast, the axis C4 of the idler shaft 64 supported on the split plane A extends in the longitudinal direction of the vehicle body at a right lower position with respect to the axis CI of the crankshaft 31. As a result, the center shaft 93 of the transmission 91 and the idler shaft 64 are positioned on the opposite sides with respect to the crankshaft 31, thereby reducing the lateral size of the power unit 7 to make it compact as compared with the case of locating such two rotating shafts on one side of the crankshaft 31.

Thus, the front end portion of the center shaft 93 is supported to the front end portions of the upper and lower crankcases 42U and 42L. Further, the front end portion of the center shaft 93 is positioned on the front side of the rear end portion of the crankshaft 31. Accordingly, the crankshaft 31 and the center shaft 93 can be arranged so as to be overlapped in the longitudinal direction of the vehicle body, so that the length of the power unit 7 along the longitudinal

direction of the vehicle body can be reduced to thereby make the power unit 7 compact.

The transmission 91 will now be described in more detail in connection with its operation.
The second drive gear 61 of the crankshaft 31 meshes with the input gear 94. A flanged boss 101 is rotatably mounted on the center shaft 93 of the transmission 91, and the input gear 94 is mounted on a flange formed at an axially central portion of the flanged boss 101. An inner member 95a of the starting clutch 95 is mounted on a rear portion of the flanged boss 101 so as to be rotated together. A start driven gear 105 is mounted on a front portion of the flanged boss 101 through a one-way clutch 106. The start driven gear 105 meshes with a small gear 104 of an idler shaft . constituting a speed reduction mechanism of a starter motor. At starting, the rotation of the starter motor is transmitted through a pinion 102, a large gear 103 of the idler shaft, the small gear 104 of the idler shaft, the start driven gear 105, the one-way clutch 106, the input gear 94, and the second drive gear 61 to the crankshaft 31.

The starting clutch 95 coaxial with the center shaft 93 has an inner member 95a, an outer member 95b, and a centrifugal weight 95c. When the rotational speed of the inner member 95a exceeds a given speed, the centrifugal weight 95c operates to connect the inner member 95a and the outer member 95b and thereby rotate them together, thus obtaining a completely engaged condition of the starting clutch 95.
Each of the shift clutches 96, 97, and 98 has a planetary gear mechanism and a clutch mechanism. The outer member of the clutch mechanism is integrally connected with the internally toothed gear of the planetary gear mechanism, and the inner member of the clutch mechanism is integrally connected with a carrier for rotatably supporting the planetary gear of the planetary gear mechanism. The carrier has a centrifugal weight for integrating the outer member and the inner member of the clutch mechanism through a plurality of clutch plates when the rotating speed of the carrier becomes a given speed. The sun gear of the planetary gear mechanism is mounted on the center shaft 93 through a one-way clutch.

The outer member 95b of the starting clutch 95 is integrally connected with the outer member 96a of the second-speed shift clutch 96, and the carrier 96b of the second-speed shift clutch 96 is integrally connected with the outer member 97a of the third-speed shift clutch 97. Similarly, the carrier of the third-speed shift clutch 97 is integrally connected with the outer member of the fourth-speed shift, clutch 98, and the carrier of the fourth-speed shift clutch 98 is integrally connected with the output shaft 99.

Until reaching a given rotating speed where the clutch mechanism in the second-speed shift clutch 96 is operated to integrate the internally toothed gear serving also as the outer member 96a and the carrier 96b serving also as the inner member, the carrier 96b is rotated at a given reduction ratio because of the sun gear 96c kept unrotated by the one-way clutch 96d, so that the outer member 97a of the third-speed shift clutch 97 is rotated at a reduced speed. Similarly, the outer member of the fourth-speed shift clutch 98 is rotated at a given reduction ratio by the speed reducing operation of the third-speed shift clutch 97, and the output shaft 99 is rotated at a given reduction ratio by the speed reducing

operation of the fourth-speed shift clutch 98, thereby obtaining a maximum reduction ratio.

When the rotating speed of the carrier 96b in the second-speed shift clutch 96 reaches a given speed to operate the clutch mechanism and integrate the internally toothed gear and the carrier 96b, the second-speed shift clutch 96 is rotated as a unit without carrying out its speed reducing operation. Until the carrier in the third-speed shift clutch 97 reaches a given speed, the carrier is rotated at a given reduction ratio, and the outer member of the fourth-speed shift clutch 98 is rotated at a reduced speed. Further, the output shaft 99 is rotated at a given reduction ratio by the speed reducing operation of the fourth-speed shift clutch 98, thereby obtaining a smaller reduction ratio.
Similarly, when the clutch mechanism in the third-speed shift clutch 97 is operated and the third-speed shift clutch 97 is rotated as a unit without carrying out its speed reducing operation, the output shaft 99 is rotated at a given reduction ratio by the speed reducing operation of the fourth-speed shift clutch 98, thereby obtaining a smaller reduction ratio. Further, when the

fourth-speed shift clutch 98 is rotated as a unit without carrying out its speed reducing operation by the operation of the clutch mechanism, the inner member 95a of the starting clutch 95 is directly coupled to the output shaft 99, so that the output shaft 99 is rotated at the same speed as that of the inner member 95a.
The above given rotating speeds have different values, which are suitably set in consideration of speed shift characteristics.
The output from the transmission 91 operated above is transmitted to the rear wheel 6 by the shift drive mechanism. That is, an output gear 107 is mounted on the output shaft 99 of the transmission 91 so as to be rotated together. The output gear 107 meshes with a gear 112 fixed to the drive shaft,111 of the final drive 110. The drive shaft 111 is located nearer to the vehicle body center CO than the center shaft 93 and has an axis C6 extending in the longitudinal direction of the vehicle body. A rear end portion of the drive shaft 111 is formed with a bevel gear (not shown), and this bevel gear meshes with a driven bevel gear mounted on the axle of the rear wheel 6. In this manner, the rotation of the output shaft

99 is reduced in speed and transmitted to the rear wheel 6, thereby driving the rear wheel 6. The axis CI of the crankshaft 31 is located below the axis C6 of the drive shaft 111 set according to the size of the rear wheel 6, thereby lowering the center of gravity of the power unit 7 and accordingly lowering the center of gravity of the vehicle body (see FIG. 1) .
Further, a rotational speed sensor 113 for detecting a rotational signal from the drive shaft 111 is mounted on the case of the final drive 110, so as to detect the rotating speed of the output shaft 99 of the transmission 91 for control of the internal combustion engine 30.
This preferred embodiment can exhibit the following effects by the above-mentioned configuration.
With respect to the axis CI of the crankshaft 31 extending in the longitudinal direction of the vehicle body and located in the vicinity of the vehicle body center CO, the axis C2 of the cylinder 45 is inclined so as to be raised on the right side, and. the axis C5 of the center shaft 93 of the planetary gear transmission 91 as a component of the power transmitting device 90 extends

in parallel to the axis C1 at a left upper position with respect thereto. That is, the transmission 91 is,Inclined so as to be raised on the left side at substantially the same angle as the angle of inclination of the cylinder 45 with respect to the vehicle body center CO. As a result, the bank angle of the vehicle body can be enlarged in the motorcycle 1 having the power unit 7 located at a lower portion of the vehicle body to lower the center of gravity of the vehicle body. Furthermore, since the cylinder 45 and the transmission 91 are inclined at substantially the same angle, the lateral balance of the power unit 7 can be ensured.
The front end of the center shaft 93 of the planetary gear transmission 91 is supported to the inner surfaces of the front end portions of the upper and lower crankcases 42U and 42L at a position on the front side of the rear end of the crankshaft 31. Accordingly, the length of the power unit 7 along the longitudinal direction of the vehicle body can be reduced to thereby make the power unit 7 compact.
The axis C1 of the crankshaft 31 is located below the axis C6 of the drive shaft 111. Accordingly, the

center of gravity of the power unit 7 can be lowered to thereby lower the center of gravity of the vehicle body under the condition where a required height of the drive shaft 111 for driving the axle on which the rear wheel 6 is mounted is ensured.
The idler shaft 64 is mounted on the joint surfaces of the upper and lower crankcases 42U and 42L which surfaces form the split plane A, and the camshaft 53 is mounted on the joint surfaces of the cylinder 45 and the cylinder head 43 which surfaces form the mounting plane B. Accordingly, the mountability of the idler shaft 64 and the camshaft 53 can be improved.
The camshaft 53 and the idler shaft 64 are located on the side where the split plane A and the mounting plane B intersect each other with respect to the axis C2 of the cylinder 45, that is, on the side where both planes A and B approach each other. With this arrangement of the camshaft 53 and the idler shaft 64, the idler shaft 64 supported on the split plane A and the camshaft 53 supported on the mounting plane B can be located close to each other. Accordingly, no intermediate shaft is required between the idler shaft 64 and the camshaft 53,

but the idler shaft 64 and the camshaft 53 can be directly coupled by the smaller gear 66 and the cam gear 67. As a result, the axial height of the cylinder 45 can be reduced, thereby reducing the lateral size of the power unit 7 to make it compact. Further, the number of parts can be reduced because no intermediate shaft is required as mentioned above.

Further, since the camshaft 53 and the idler shaft 64 are positioned below the cylinder 45 obliquely raised from the crankshaft 31 on the right side, the center of gravity of the power unit 7 can be lowered.
Further, this close arrangement of the camshaft 53 and the idler shaft 64 as a coaxial two-shaft type rotating shaft having a plurality of functions results in an effective use of the small space interposed between the split plane A and the mounting plane B on one side of the cylinder 45, so that a large space.having no rotating shafts can be formed on the other side of the cylinder 45, and the radiator 41 as one of the peripheral parts can be located in this large space as mentioned above.
A V-shaped space is formed by the upper crankcase

42U and the cylinder head 43, and the radiator 41 can be compactly located in this V-shaped space, thereby making the power unit 7 compact.
The camshaft 53 is located on the mounting plane B between the cylinder 45 and the cylinder head 43, so that the height of the cylinder head 43 can be reduced. Additionally, the camshaft 53 is located in the small space interposed between the split plane A and the mounting plane B on one side of the cylinder 45 as mentioned above. Accordingly, the internal combustion engine 3 0 can be made compact.
The center shaft 93 of the transmission 91 and the idler shaft 64 are located on the opposite sides of the crankshaft 31. Accordingly, as compared with the case of locating such two rotating shafts on one side of the crankshaft 31, the lateral size of the power unit 7 can be reduced to thereby make the power unit 7 compact.
The idler shaft 64 provided in a drive mechanism for driving the camshaft 53 is formed as a coaxial two-shaft type rotating shaft to thereby function both as a drive shaft for driving the cooling water pump 79 and as

a balancer shaft. As a result, the cost can be reduced as compared with the case of providing rotating shafts having these functions in addition to the idler shaft 64.
FIG. 4 is a view similar to FIG. 3, showing a second preferred embodiment of the present invention. The second preferred embodiment is different from the first preferred embodiment in the structure of the.power transmitting device in the power unit 7. The structure of the other portion is basically the same as that of the first preferred embodiment, so the same parts are denoted by the same reference numerals and the detailed description thereof will be omitted herein.
Reference numeral 120 denotes a power transmitting device in the second preferred embodiment. The power transmitting device 120 includes a hydraulic transmission 121 having swash plates. The transmission 121 includes an input gear 122, a fixed capacity type swash hydraulic pump 123, a variable capacity type swash hydraulic motor 124, and an output shaft 125. The output shaft 125 having an axis C7 extending in the longitudinal direction of the vehicle body is a center shaft of the transmission 121. A front end portion of the output shaft 125 is supported

through a bearing 126 to the inner surfaces of the front end portions of the upper and lower crankcases 42U and 42L. The bearing 126 is fitted with a pair of semicylindrical recesses formed on the upper and lower crankcases 42U and 42L so as to be exposed to the split plane A. A rear end portion of the output shaft 125 is supported through a bearing 128 to a support shaft inserted in a hole formed through the rear end wall of a transmission case 127. Accordingly, the axis C7 of the output shaft 125 is contained in the split plane A between the upper and lower crankcases 42U and 42L.
Since the front end portion of the output shaft 125 is supported to the front end portions of the upper and lower crankcases 42U and 42L, the front end of the output shaft 125 is positioned on the front side of the rear end of the crankshaft 31 in the longitudinal direction of the vehicle body. Accordingly, the crankshaft 31 and the output shaft 125 can be arranged so as to be overlapped in the longitudinal direction of the vehicle body, thereby reducing the length of the power unit 7 along the longitudinal direction of the vehicle body and accordingly making the power unit 7 compact.

The second drive gear 61 mounted on the crankshaft 31 meshes with the input gear 122 formed integrally with a housing 123a of the hydraulic pump 123. A start driven gear 129 meshing with the small gear of the idler shaft constituting the speed reduction mechanism of the starter motor is mounted through a one-way clutch 130 to a front portion of the housing 123a. The rotation of the starter motor at starting is transmitted to the crankshaft 31 in the same manner as that in the first preferred embodiment
The hydraulic pump 123 includes a swash plate 123c for driving a plurality of pistons 123b in the housing 123a- The swash plate 123c is tilted by the rotation of the housing 123a to thereby drive each piston 123b and generate a high hydraulic pressure. The hydraulic motor 124 includes a cylinder block 124a having a plurality of pistons 124b, and a swash plate 124c. The cylinder block 124a is integrally connected with the output shaft 125.
The hydraulic pressure from the hydraulic pump 123 is controlled by a control valve and supplied to the hydraulic motor 124. Then, each piston 124b is driven by the hydraulic pressure supplied to come into abutment against the swash plate 124c. As a result, the cylinder

block 124a is rotated to thereby integrally rotate the output shaft 125. The rotating speed of the output shaft 125 can be continuously varied by changing the angle of the swash plate 124c by means of an actuator. Further, the rotation of the output shaft 125 may be interrupted, that is, the transmission of the rotation of the input gear 122 to the output shaft 125 may be interrupted by the above control valve.
An output gear 131 mounted on the output shaft 125 of the hydraulic transmission 121 meshes with a gear fixed to a drive shaft 141 of a final drive 140. The drive shaft 141 has an axis C8 extending in the longitudinal direction of the vehicle body. A rear end portion of the drive shaft 141 is formed with a bevel gear 141a. The bevel gear 141a meshes with a driven bevel gear 142 mounted on an axle 143 of the rear wheel 6. Thus, the rotation of the output shaft 125 is reduced in speed and transmitted to the axle 143, thereby driving the rear wheel 6. Like the first preferred embodiment, the axis C1 of the crankshaft 31 is located below the axis C8 of the drive shaft 141, thereby lowering the center of gravity of the power unit 7 and accordingly lowering the center of gravity of the vehicle body.

A rotational speed sensor 144 for detecting a rotational signal from the drive shaft 141 is mounted on the case of the final drive 140, so as to detect the rotating speed of the output shaft 125 of the transmission 121 for control of the internal combustion engine 30 and the transmission 121.
The second preferred embodiment can also exhibit the same effects as those of the first preferred embodiment. In addition, the power unit 7 in the second preferred embodiment can be made more compact than that in the first preferred embodiment, because the length of the hydraulic transmission 121 along the longitudinal direction is smaller than that of the planetary gear transmission 91 in the first preferred embodiment.
While the center shaft 93 of the planetary gear transmission 91, the output shaft 125 of the hydraulic transmission 121, and the idler shaft 64 are supported on the split plane A between the upper and lower crankcases 42U and 42L in the first and second preferred embodiments, these shafts may be supported to the crankcase 42 at any positions other than on the split plane A. Similarly, the

camshaft 53 may be supported to the cylinder head 43 only rather than on the mounting plane B.
While the motorcycle 1 in each of the first and second preferred embodiments is of a scooter type, the motorcycle to which the present invention is applicable may be any type of motorcycle other than the scooter type.

[Explanation of Reference Numerals]
1: motorcycle 2; bolt 3: front frame .4: rear frame 5: front wheel 6: tear wheel 7: power unit 8: seat 9: front fender 10; front cover 11: step floor 12: frame body cover 13: rear fender 14: side cover 15: storage box 16: swing arm 17: shock absorber 18: kingpin 19: axle holder 20: axle 21: head pipe 22: handle post 23: steering arm 24: link 25: bracket 26: hanger hole 27: shock absorber
30: internal combustion engine 31: crankshaft 32: air cleaner 33: air induction pipe 34: throttle body 35: intake pipe 36: fuel injector 37: fuel tank 38: exhaust pipe 39; exhaust muffler 40: fan cover 41: radiator 42: crankcase 43: cylinder head 44: cylinder head cover 45: cylinder 46: tubular bushing 47: piston 48: connecting rod 49, 50: main bearing 51: spark plug 52: supercharger 53: camshaft 54, 55: bearing 56: AC generator 57: nut 58: cooling fan 59: bolt 60, 61: drive gear 62: oil pump 63: suction passage 64: idler shaft 65, 66, 67: gear 68: intake valve 69: supercharging valve 70, 71: intake rocker arm 72: rod 73, 74: supercharging rocker arm 75: rod 76: rotational position sensor 77, 78: bearing 79: cooling water pump 80: water guide pipe 81: discharge hole 82: thermostat 83: weight

90: power transmitting device 91: planetary gear transmission 92: transmission case 93: center shaft 94: input gear 95: starting clutch 96, 97, 98: shift clutch 99: output shaft 100: rotation stop member 101: flanged boss 102: pinion 103, 104, 105: gear 106: one-way clutch 107: output gear
110: final drive 111: drive shaft 112: gear 113: rotational speed sensor
120: power transmitting device 121: hydraulic transmission 122: input gear 123: swash hydraulic pump 124: swash hydraulic motor 125: output shaft 126: bearing 127: transmission case 128: bearing 129: gear 130: one-way clutch 131: output gear
140: final drive 141: drive shaft 142: gear 143: axle 144: rotational speed sensor
A: split plane B: mounting plane CO: vehicle body center C1 to C8: axis

We Claim:
1. A power unit for a motorcycle comprising an internal combustion engine having a crankshaft whose axis extends in the longitudinal direction of a vehicle body of said motorcycle, and a power transmitting device for transmitting power from said crankshaft to a rear wheel, said power unit being located at a lower portion of said vehicle body wherein:
the axis of said crankshaft is positioned in the vicinity of a vehicle body center;
the axis of a cylinder of said internal combustion engine extends from
the axis of said crankshaft in orthogonal relationship thereto and is inclined
with respect to said vehicle body center so as to be raised on one said of said
vehicle body
the axis of a center shaft of a transmission in said power transmitting device extends in the longitudinal direction of said vehicle body and is positioned above the axis of said crankshaft on the other side of said vehicle body; and
the front end of said center shaft is positioned on the front side of the rear end of said crankshaft.
2. A power unit for a motorcycle as claimed in claim 1, wherein said power transmitting device has a shaft drive mechanism for driving an axle on which said rear wheel is mounted, and the axis of said crankshaft is positioned below the axis of a drive shaft of said shaft drive mechanism.
3. A power unit for a motorcycle substantially as herein described with reference to the accompanying drawings.
Dated this 8th day of May, 2000.

(JAYANTA PAL)
OF REMFRY& SAGAR
ATTORNEY FOR THE APPLICANTS

Documents:

419-mum-2000-cancelled pages(10-05-2005).pdf

419-mum-2000-claims(granted)-(10-05-2005).pdf

419-mum-2000-claims(granted)-(10-5-2005).doc

419-mum-2000-correspondence(28-03-2006).pdf

419-mum-2000-correspondence(ipo)-(12-05-2004).pdf

419-mum-2000-drawing(10-05-2005).pdf

419-mum-2000-form 1(08-05-2000).pdf

419-mum-2000-form 19(15-04-2004).pdf

419-mum-2000-form 2(granted)-(10-05-2005).pdf

419-mum-2000-form 2(granted)-(10-5-2005).doc

419-mum-2000-form 3(08-05-2000).pdf

419-mum-2000-form 3(10-05-2005).pdf

419-mum-2000-form 3(20-02-2001).pdf

419-mum-2000-form 5(08-05-2000).pdf

419-mum-2000-petition under rule 137(10-05-2005).pdf

419-mum-2000-petition under rule 138(10-05-2005).pdf

419-mum-2000-power of authority(04-09-2000).pdf

419-mum-2000-power of authority(10-05-2005).pdf

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Patent Number

204357

Indian Patent Application Number

419/MUM/2000

PG Journal Number

43/2008

Publication Date

24-Oct-2008

Grant Date

15-Feb-2007

Date of Filing

08-May-2000

Name of Patentee

HONDA GIKEN KOGYO KABUSHIKI KAISHA

Applicant Address

1-1 MINAMIAOYAMA 2-CHOME MINATO-KU, TOKYO, JAPAN.

Inventors:

#	Inventor's Name	Inventor's Address
1	ATSUSHI OGASAWARA	C/O KABUSHIKI KAISHA HONDA GIJUTSU KENKYUSHO, 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA, JAPAN.

PCT International Classification Number

B 62 M 7/02

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	HEI - 11 - 177735	1999-06-24	Japan