Title of Invention

''TRANSMISSION SYSTEM FOR AUTOMOBILE''

Abstract

| Problem| To provide a vehicle transmission system provided with a start clutch, a transfer clutch and a gear selector, wherein a braking force is applied to the start clutch each time a shift up operation is carried from first gear up through to the highest gear, and suppresses shocks and impact noise, as well as making it possible to carry out the gear change operation simply. [Means of Solving the Problem] An overhead valve single cylinder internal combustion engine 1 is provided with a start clutch 20, a transfer clutch 30, a gear selector (not shown) and a gear shift operating mechanism 50. By causing a change spindle to rotate in a clockwise direction, a braking force is applied to the clutch outer 21 of a start clutch 20 by bringing a brake lining 72 of a brake mechanism 70 into contact with the clutch outer 21 of a start clutch 20, and the transfer clutch is disengaged. Also, by causing a shift drum 45 and star cam 49 to rotate in a counter clockwise direction, the gear selector 40 shifts up.

Full Text

The present invention relates to a transmission system .for an automobile provided with a start clutch, a transfer clutch and a gear selector, and particularly to a transmission system for a motor cycle. The present invention also relates to a transmission system for an automobile which applies a braking force to a braking member of said start clutch riot only at the time of shifting up from neutral to first gear, but when shifting up from all the gears from first to the highest gear, and suppresses shocks and noise, and which can carry out a gear change operation easily. In a conventional automobile transmission system where an internal combustion engine is mounted in a vehicle, an output side clutch outer of a start clutch is engaged with a crankshaft of this internal combustion engine so as to rotate relative to the crankcase, and power is transmined from the crankshaft to vehicle axles via the start clutch, a transfer clutch and a gear selector, when the engine is allowed to run and the gear shift operating mechanism is set to neutral while the vehicle is stopped, the clutch outer of the start clutch turns following rotation of a crankshaft, and a connected gear shift clutch and main shaft also rotate in response to rotation of the crankshaft. However, since a counter shaft connected to the vehicle axle is stopped, when shifting up from neutral to first gear, for example, a transfer clutch is also stopped for the duration of the shift operation, with the result that a main shaft and a gear on the main shaft are rotated by that rotational inertia, and impact force and noise are generated by the engaging of the rotating gear on the main shaft and a stopped gear on the counter shaft. In order to prevent the above described impact force and noise, as disclosed in Japanese Patent laid Open Publication No. Hei. 2-212&Z5, a shift drum of a gear changer is provided integrally with a cam, and a brake shoe connected to a clutch outer of a start clutch is also provided, and when shifting up from neutral to first gear, the break shoe is brought into contact with the clutch outer by the cam, and the clutch outer is stopped together a gear on the main shaft. |Problems to be Solved by the Invention] In the invention disclosed in the above mentioned laid-open publication, because a braking force is only applied to the clutch outer of the start clutch when changing from neutral to first gear, the construction is complex, which leads to the drawbacks that the number of components is increased and the cost becomes expensive. Further, in the invention disclosed in the above mentioned laid-open publication, because the spring force of a spring for urging the brake shoe against the clutch outer is different for first gear and other gears, there are variations in the gear shift operation, which leads to the drawback that the feel of the shift operation differs. | Means and Effect of solving the Problems] .The present invention, relates to an improvement to a vehicle transmission system that solves the above described drawbacks, and is constituted by a transmission system for an automobile having an output member of a start clutch mutually and relatively engaged with a crankshaft of an internal combustion engine mounted in the vehicle and transmitting power from the crankshaft to vehicle axles via the start clutch, a transfer clutch and a gear selector, wherein a gear shift transfer braking member is provided to apply a braking force to the output member of the start clutch, at the time of a gear shift up operation of a gear shift operating mechanism so as to vary a gear shift ratio of the gear selector, the gear shift transfer braking member not being limited to the time of shifting up from neutral to first gear but operating for every shift up from first gear to the highest gear. The present invention has the above described construction, and an interlock mechanism for selectively bringing a special cam for braking the output member of the start clutch, and a brake shoe interlocking with this special cam, into contact with the stan clutch to a shift drum of the gear selector becomes unnecessary, the construction is simplified and the number of components is reduced, which means that the cost can be reduced. Further, in the present invention, because a braking force is supplied to the output member of the start clutch with a shift up operation to any gear, there is no disparity in the operating force for a shift up to each gear, and the feel of the shift up is improved. At the time of shifting up, in order to bring the peripheral velocity of the a gear on the input side of the gear selector into agreement with the peripheral velocity of a gear on the output side, the gear on the input side of the gear selector is caused to decelerate by closing the throttle valve and reducing the rotational velocity of the crankshaft, but in the present invention the gear on the input side of the gear selector can be decelerated by applying a braking force to the output member of the start clutch connected to the crankshaft, which means that even if the extent of operation of the throttle valve is small, the gear meshing between the gears on the input side of the gear selector is executed smoothly and the extent of shocks and noise occurring at the time of gear changing is further reduced. Accordingly, there is provided a transmission system for an automobile having an output member of a start clutch engaged so as to be rotatable relative to a crankshaft of an internal combustion engine mounted in the vehicle and transmitting power from the crankshaft to vehicle axles via said start clutch, a transfer clutch and a gear selector, wherein a gear shift transfer braking member is provided to apply a braking force to a large-diameter portion of said output member of the start clutch, only at the time of each gear shift up operation of a gear shift operating mechanism so as to vary a gear shift ratio of said gear selector in a gear shift up range from a neutral stage to a final gear shift stage, and said gear shift transfer braking member is connected directly to a clutch operation member of said transfer clutch for braking said output member of said start clutch in interlocking with shift up operation of said transfer clutch at each gear shift stage. IBrief Description of the Drawings] Fig. 1 is a left side view of an overhead valve single cylinder internal combustion engine provided with a vehicle transmission system according to the present invention. Fig. 2 is an expanded partially cut away right side view of essential parts of Fig. 1. Fig. 3 is a vertical plan cross section taken along line III - III of Fig. 1. Fig. 4 is a vertical plan cross section taken along line IV - IV of Fig. 2. Fig. 5 is a side view of a gear shift operating mechanism in neutral. Fig. 6 is a side view of a gear shift operating mechanism showing the state where the clutch lever has been operated for shifting up to first gear. Fig. 7 is a side view similar to Fig. 5 but with the clutch lever, lifter cam plate and brake mechanism removed. Fig. 8 is a side view similar to Fig. 6 but with the clutch lever, lifter cam plate and brake mechanism removed. Fig. 9 is a side view, in neutral, of the clutch outer of the start clutch, clutch lever and lifter cam plate, with the shift drum, star cam, shift master arm and brake mechanism removed. Fig. 10 is side view similar to Fig. 9, showing the state where the clutch lever has been operated for shifting up to first gear. I Embodiments of the Invention] An embodiment of a vehicle transmission system of the present invention will be described below. The overhead valve single cylinder internal combustion engine 1 equipped with the vehicle transmission system of the present invention is a spark ignition 4-stroke interna! combustion engine. In a motor cycle not shown in the drawings, a cylinder block 3 and a cylinder head 4 are mounted oriented substantially in a forward horizontal direction, and in the overhead valve single cylinder internal combustion engine 1 a cylinder block 3, cylinder head and head cover are sequentially stacked forward of the crankcase 2 divided in the left and right direction, and integrally coupled by coupling means such as bolts (not shown) etc. A left crankcase 6 and a right crankcase 7 are integrally coupled on both the left and right sides of the crankcase 2 by bolts (not shown). A piston 9 is engaged in a cylinder cavity 8 formed in the cylinder block 3 so as to be freely slidable in a forward direction, and a crankshaft is rotatably supported in the crankcase 2 via a bearing 11. Both ends of a connecting rod 14 are rotatably engaged with a crank pin 12 of the crankshaft 10 and the piston pin of the piston 9, and the crankshaft 10 is driven to rotate by the reciprocation of the piston 9. A variable-venturi type carburetor 15 is connected to the cylinder cavity 8 through an intake air port (not shown), and in the variable-venturi type carburetor 15 a venturi piston (not shown) used with a throttle valve is connected to a throttle grip (not shown) through a throttle cable 16. The venturi piston rises and falls as a result of operation of the throttle grip, and the intake air amount, in other words the amount of supplied fuel, is regulated. A valve system drive sprocket 17 is engaged with the left side of the crankshaft 10, and a starter driven sprocket 18, attached to a one way clutch connected to a starter motor (not shown) and a generator 19 are also provided on the left side of the crankshaft 10. A clutch outer 21 of the start clutch 20 is relatively rotatably engaged with the right side of the crankshaft 10. A clutch inner 22 of the start clutch 20 is integrally attached to the right end of the crankshaft 10, and the base ends of three clutch weights are attached along the rotating surface of the clutch inner 22 at equal intervals in the circumferential direction of the clutch inner 22, so as to swing freely, and a return spring 25 is stretched between the base end of the clutch weights 23 and the front end of the clutch weights 23 adjacent to them. With the crankshaft 10 stopped or below a specified rotational speed, the front end of the clutch weights 23 are drawn in the direction of the crankshaft 10 by the extension spring force of the return spring 25, and the start clutch 20 becomes disengaged due to the clutch shoe 24 of the clutch weights 23 being separated from the inner peripheral surface of the clutch outer 21. If the crankshaft 10 rotates faster than a specified rotational speed, the clutch weights 23 move radially outward against the extension spring force of the return spring 25 using the centrifugal force due to the movement of clutch weights 23, the clutch shoe 24 presses against the inner peripheral surface of the clutch outer 21 and the start clutch is engaged. With respect to the crankcase 2, a gear selector 40 is located at the rear of the crankshaft 10, a main shaft 41 being an input axis of the gear selector 40 and a counter shaft being an output axis of the gear selector 40 are arranged in a straight line in the front to back direction, and these shafts are rotatably supported in the crankcase 2. A transfer clutch 30 is arranged at the right side of the main shaft 41 of the gear selector 40, and a drive gear 26 is integrally formed on the left end of the clutch outer 21 of the start clutch 20. An outer driver 31 of the transfer clutch 30 is rotatably engaged at the right side section of the main shaft 41 projecting further to the right than the crankcase 2, and an inner driver 32 is integrally engaged in the right end of the main shaft 41. A driven gear 27 is integrally attached to the outer driver 31, and this driven gear 27 meshes with integral drive gear 26 formed integrally with the clutch outer 21 of the start clutch 20. A plurality of clutch friction plates 33 for connecting with an outer driver of the transfer clutch, and a plurality of clutch plates 34 for connecting with an inner driver 32 are alternately arranged and a pressure plate 35 is arranged between a circular plate portion 32a of an inner driver and a circular plate portion 3la of an outer driver so as to be slidably engaged with a cylindrical section 32b of an inner driver 32 along a center line of the main shaft 41. Four pressure plate sleeves 35b (arranged at equal intervals in the circumferential direction) penetrate the inner driver and protrude further than the circular plate portion 35a of the pressure plate in the right direction. A lifter cam plate 36 is held by bolts 37 and integrally attached to the front edge of the sleeves 35b of this pressure plate 35. A compression coil spring 38 engaged with the sleeves 35b of the pressure plate is held between a circular plate section 32a of the inner driver 32 and a lifter cam plate 36, and a bearing 39 is engaged with the lifter cam plate 36. With a gear shift operating mechanism 50 that will be described later set in one of neutral, first gear, or any other gear, an axis 58 of the lifter cam plate 57 for engaging with a central portion of the bearing 39 is positioned in the right direction by a pressure plate 35 and a lifter cam plate 36, as well as the spring force of a compression coil spring 38, which means that a frictional force is generated between them, and the transfer clutch 30 is engaged. However, during the gear change operation of the gear selector 40, a lifter cam plate 57 is projected in the left direction against the spring force of the compression coil spring 38, and as a result of the fact that the pressure plate 35 and the lifter cam plate 36 are also moved in the left direction, the clutch friction plate 33 and the transfer clutch 30 are separated from one another so a frictional force between the two is decreased or curtailed altogether, and the transfer clutch 30 becomes switched to a disengaged state. With respect to the gear selector 40, a main gear cluster 43 and a counter gear cluster 44 are respectively engaged with the main shaft and the counter shaft 42, and if the shift drum 45 is rotated intermittently about 72 degrees in one direction or the opposite direction, by means of the gear shift operation of the gear shift operating mechanism 50, the main gear cluster 43 and the counter gear cluster 44 selectively mesh due to the appropriate left and right movement of shift forks 46, 47 connected to a shift cam mechanism 45 of this shift drum 45. The gear selector 40 shifts up from neutral, to first and second gear, and shifts down from fourth gear to third gear and second gear. In the gear shift operating mechanism 50, a change spindle 51 is rotatably supported in the crankcase 2 parallel to the crankshaft 10, and a change pedal (not shown) is integrally fixed to left end of the change spindle 5 1 protruding further to the left than the crankcase 2, while a clutch lever 52 is integrally fixed to the right end of the change spindle 51 protruding further to the right than the crankcase 2, and a lever pin 53 is provided on the tip of the clutch lever 52. As shown in Fig. 4, a pivot shaft 54 is located on a line extending to the right of the main shaft 41 and integrally attached to the right crankcase cover 7. A clutch lifter 55 is engaged with this pivot shaft 54, while a boss 55a of this clutch lifter 55 is engaged with a cavity 7a of the right crankcase cover 7, rollers 56 are rotatably engaged in forked portions 55b coming out from three sides of the clutch lifter 55, and a cylindrical concave portion 57a of a lifter cam plate 57 is rotatably engaged in a central axis portion 55c of the clutch lifter 55. Radial hollow channels 57b are formed facing from the right side to the left side at points corresponding to the forked portions 55b of the clutch lifter 55, while an elongated guide slot 57d is formed in an extended portion of the lifter cam plate 57, the lever pin 53 of the clutch lever 52 is engaged via the roller 53 a with the elongated guide slot 57d of the lifter cam plate 57, a shaft 58 is integrally provided in a central slot of the lifter cam plate 57 so as to project in the left direction, and this shaft 58 is engaged with the inside 39a of the bearing 39. When no force is applied to the change pedal (not shown) the rollers 56 of the forked portions 55b of the clutch lifter 55 fall into the channels 57b of the lifter cam plate 57, the lifter cam plate 57, shaft 58, bearing 39 and pressure plate 35 are located in the right direction and the transfer clutch 30 is engaged. However, when the change spindle 51 is rotated by operation of the change pedal (not shown) and the clutch lever 52 moved, the lifter cam plate 57 also moves, the rollers 56 of the forked portions 55b of the clutch lifter 55 are further out than the channels 57b of the lifter cam plate 57, and the lifter cam plate 57, shaft 58, bearing 39 and pressure plate 35 are moved to the left, and so the transfer clutch 30 is disengaged. As shown in Fig. 4, spindle positioning plate 60 is integrally attached to the change spindle 51, between the clutch lever 52 and the crankcase 2, and adjacent to the crankcase 2. A sleeve 61 is rotatably engaged with the change spindle 51 between this spindle positioning plate 60 and the crankcase 2, a shift master arm 62 is integrally fixed to this sleeve 61, and a piece 62a is punched out at right angles to this shift master arm 62 in the left direction at the same time leaving a space 62b. The end part 60a of the spindle positioning plate 60 is also bent to the left, and as shown in Fig. 7 and Fig. 8, a pin 63 is attached so as to protrude to the right from the crankcase 2 to be located between the punched piece 62a of the shift master arm 62 and the bent piece 60a of the spindle positioning plate 60. The two ends 64a and 64b of a coil spring 64 wound around the sleeve 61 sandwich the punched piece 62a of the shift master arm 62, the pin 63 and the bent piece 60a of the spindle positioning plate 60. A base section 65a of a shift arm 65 is hinged to a tip portion 62c of the shift master arm 62, an extension coil spring 66 is stretched between the tip 62d of the shift master arm 62 and the shift arm 65, and engagement claws 65b and 65c are formed at a tip portion of the shift arm 65 and close to the central portion of the shift arm 65. The shift arm 65 is pressed against projecting engagement pins 48 that are provided on the right side of the shift drum 45 around the peripheral direction thereof at substantially equal intervals, by the spring force of the extension coil spring 66. The shift drum 45 turns 72 degree in either a clockwise direction or counter-clockwise direction as a result of the engagement claws 65b and 65c of the shift arm being engaged with the engagement pins, by one complete swing of the shift master arm 62 to the front or to the rear of the vehicle frame. A star cam 49 is integrally attached to the right end of the shift drum 45, a stop plate 67 is supported in the crankcase 2 and located in a lower rear direction of the shift drum 45, and roller 68 is rotatably attached to the tip of the stop plate 67. A roller 68 of the stop plate 67 is pressed against the star cam 49 under the spring force of the return spring 69 provided at the base portion of the stop plate 67, and the shift drum 45 is maintained at an appointed rotation angle. Further, a support shaft 52a is fixed to the clutch lever 52, and a brake lever 71 of the brake mechanism 70 is supported by this shaft 52a. The tip portion of this brake lever 71 is bent at a right angle, and a brake lining 72 is provided on the outside of the bent portion. Pins 73 and 74 are provided so as to extend from the clutch lever 52 and the brake lever 71, and are hinged to the support shaft 52a and held by the two ends 75a and 75b of the coil spring 75. Because the illustrated embodiment has the above described construction, in the case where the gear selector 40 is set in neutral and the overhead valve single cylinder internal combustion engine 1 is stopped, the transfer clutch 30 is engaged, but the start clutch 20 is disengaged. When the overhead valve single cylinder internal combustion engine 1 is started, the crankshaft 10 is rotated, and even if the start clutch 20 is disengaged the clutch outer 21 of the start clutch 20 is engaged with the crankshaft 10 and the clutch outer 21 moves around due to the frictional force between the two. The clutch outer 21 rotates in the direction of the arrow in Fig. 5, and the outer driver 31 of the transfer clutch 30 connected through the drive gear 26 and the driven gear 27 also rotates, but when a change pedal is stepped on so as to shift up from neutral to first gear, the clutch lever 52 swings together with the brake lever 71 in the clockwise direction, as shown in Fig. 6, the brake lining 72 comes into pressure contact with the outer peripheral surface of the clutch outer 21, and the outer driver 31 is stopped due to operation of the brake mechanism 70. This means that with respect to while the counter shaft 42 and the counter gear cluster 44 connected to the rear axle of a motorcycle are stopped, the outer driver 31 and inner driver 32 of the transfer clutch 30, and the main shaft 41 and main gear cluster 43 of the gear selector 40 are not caused to rotate reciprocally, with the result that there is no occurrence of shock and impact noise within the gear selector 40, and the gear change operation of the gear shift operating mechanism 50 is carried out smoothly. When the change pedal is stepped on and returned to its original position upon completion of shifting up from neutral to first gear, braking of the outer driver 31 of the transfer clutch 30 is removed by the brake mechanism 70 and the transfer clutch is returned to an engaged state. After that, if the overhead valve single cylinder internal combustion engine 1 is accelerated by operation of the throttle valve, the start clutch 20 is gradually connected, the torque of the crankshaft 10 is transmitted to the rear axle of the vehicle via the start clutch 20, the transfer clutch 30 and the gear selector 40, and it is possible to start the motorcycle. After the motorcycle has been started and accelerated to a certain speed, if the throttle valve is operated in such a direction as to decelerate and the shift pedal is operated in the direction to change up gear, the outer driver 31 of the transfer clutch 30 decelerates together with deceleration of the overhead valve single cylinder internal combustion engine, and after that the shift drum 45 is rotated about 72 degrees by the swinging motion of the shift master arm 62 accompanying disengagement of the transfer clutch 30, and the gear selector shifts up from first gear to second gear. Upon completion of the shift up operation, when the change pedal is trodden on again, braking of the transfer clutch 30 is released by the brake mechanism 70, similarly to the way described above, the transfer clutch 30 is returned to an engaged state and the motorcycle cab travel in second gear. In this way, because the transfer clutch 30 is braked by the brake mechanism 70 and the main shaft 41 is decelerated at the time of shifting up from neutral to first gear, from first gear to second gear, etc., selection of the meshing of the main gear cluster 43 and the counter gear cluster 44 is carried out smoothly, and it is possible to suppress the occurrence of shocks and impact noise accompanying the shift up operation as much as possible. Conversely, when the change pedal (not shown) is operated in the reverse direction, since the clutch lever 52 swings in a direction so as to move away from the transfer clutch 30, there is no braking operation on the outer driver 31 by the brake mechanism 70 and shifting down is carried out by disengaging the transfer clutch 30 and rotating the shift drum 45 about 72 degrees in the reverse direction. In the thus illustrated embodiment, since the outer driver 31 of the transfer clutch 30 is only selectively braked at the time of shifting up from neutral to first gear, the construction of the gear shift operating mechanism 50 is simplified and the number of components is reduced, with the result that the cost can be decreased. Also, when shifting up, since the brake mechanism 70 acts on the outer driver 31 of the transfer clutch 30 so as to assist with temporary deceleration of the overhead valve single cylinder internal combustion engine 1 using the throttle valve, the extent of operation for shifting up can be made equal for each stage and the shift up operation can be carried out smoothly, as well as greatly reducing shocks and impact noise. Further, even if the brake lining 72 is worn, it is possible to always have the brake lining 72 in contact with the clutch outer 21 of the start clutch 20 due to the action of the coil spring 75, and it is difficult for irregularities in the braking operation of the brake mechanism 70 to occur. I Brief Description of the Numeralsl 1 overhead valve single cylinder internal combustion engine 2 crankcase 3 cylinder block 4 cylinder head 5 head cover 6 left crankcase cover 7 right crankcase cover 8 cylinder cavity 9 piston 10 crankshaft 11 bearing 12 crank pin 13 piston pin 14 connecting rod 15 variable-venturi type carburetor 16 throttle cable 17 drive sprocket 18 starter dri ven sprocket 19 generator 20 start clutch 21 clutch outer 22 clutch inner 23 clutch weight 24 clutch shoe 25 return spring 26 drive gear 27 driven gear 30 transfer clutch 31 outer driver 32 inner driver 33 clutch friction plate 34 clutch plate 35 pressure plate 36 lifter cam plate 37 boh 38 compression coil spring 39 bearing 40 gear selector 41 main shaft 42 counter shaft 43 main gear cluster 44 counter gear cluster 45 shift drum 46 shift fork 47 shift fork 48 connecting pin 49 star cam 50 gear shift operating mechanism 51 change spindle 52 clutch lever 53 lever pin 54 pivot shaft 55 clutch lifter 56 roller 57 lifter cam plate 58 pivot 60 spindle positioning plate 61 sleeve 62 shift master arm 63 pin 64 coil spring 65 shift arm 66 extension coil spring 67 stop plate 68 roller 69 return spring 70 brake mechanism 71 brake lever 72 brake lining 73 pin 74 pin 75 coil spring We Claim: 1. A transmission system for an automobile having an output member of a start clutch engaged so as to be rotatable relative to a crankshaft of an internal combustion engine mounted in the vehicle and transmitting power from the crankshaft to vehicle axles via said start clutch, a transfer clutch and a gear selector, wherein a gear shift transfer braking member is provided to apply a braking force to a large-diameter portion of said output member of the start clutch, only at the time of each gear shift up operation of a gear shift operating mechanism so as to vary a gear shift ratio of said gear selector in a gear shift up range from a neutral stage to a final gear shift stage, and said gear shift transfer braking member is connected directly to a clutch operation member of said transfer clutch for braking said output member of said start clutch in interlocking with shift up operation of said transfer clutch at each gear shift stage. 2. A transmission system substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

Documents:

2976-del-1997-abstract.pdf

2976-del-1997-claims.pdf

2976-DEL-1997-Correspondence-Others-06-05-2008.pdf

2976-del-1997-correspondence-others.pdf

2976-del-1997-correspondence-po.pdf

2976-del-1997-description (complete).pdf

2976-del-1997-drawings.pdf

2976-del-1997-form-1.pdf

2976-del-1997-form-13.pdf

2976-del-1997-form-19.pdf

2976-del-1997-form-2.pdf

2976-del-1997-form-3.pdf

2976-del-1997-form-4.pdf

2976-del-1997-form-6.pdf

2976-del-1997-gpa.pdf

2976-del-1997-petition-138.pdf

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