Title of Invention

"STRUCTURE OF ATTACHING STARTER MOTOR OF UNIT SWING TYPE INTERNAL COMBUSTION ENGINE"

Abstract

A structure of attaching a starter motor of a unit swing type internal combustion engine in a motorcycle having a unit swing type internal combustion engine having a belt power transmission device and swingably supported by a vehicle body; wherein a cylinder which is inclined forwardly is extended from a crank case at a front portion of a unit swing case; wherein a duct to the cylinder is provided from a cooling fan provided on a side of said crank case to the same side of said cylinder; wherein a starter motor is arranged on a side of said cylinder opposed to the side of said duct at a position overlapping said cylinder in a side view; wherein said cylinder is disposed between a pair of left and right rear frames both connected to a head pipe; characterized in that a starter motor is located ahead of a drive pulley composing the belt power transmission installed in an end of the crank shaft.

Full Text

The present invention relates to a structure of attaching a starter motor of a unit swing type internal combustion engine. In respect of a unit swing type internal combustion engine of this kind, there has been disclosed an example described in Japanese Examined Patent Publication No. JP-B-5-68398. Figs. 13 and 14 illustrate a structure of attaching and arranging a starter motor described in the publication. There is installed an internal combustion engine 03 in which a crank shaft 02 is arranged horizontally in the left and right direction at a center of a front portion of a unit swing case 01 and a cylinder 04 is extended upwardly. Although not illustrated, a rear wheel is axially supported at a rear portion of the unit swing case 01 and drive of the crank shaft is transmitted to the rear wheel via a belt transmission mechanism. A hanger bracket 05 is projected forwardly from a front wall of the unit swing case 01, a front end thereof is axially supported by a vehicle body frame via a pivot shaft 06, the unit swing case 01 can be swung upwardly and downwardly along with the rear wheel with the pivot shaft 06 as a center thereof, and damping means is interposed between a rear end of the unit swing case 01 and the vehicle body frame thereabove . A starter motor 07 is disposed at the front portion of the unit swing case 01 and at the same position as that of a crank pin 02a of a crank shaft 02 in respect of the left and right direction (crank center C) and is attached to the unit swing case 01 at the front position of the crank pin 02a between the cylinder 04 and the support bracket 05 with a drive shaft 07a in parallel with the crank shaft 02. The starter motor 07 is attached to the fro.nt portion of the unit swing case 01 from the side of the crank center C (right side) , a drive gear 010 formed at the drive shaft 07a of the starter motor 07 is in mesh with a large diameter gear Olla of a reduction gear Oil fitted pivotably to a reduction gear shaft 09 provided to span between the unit swing case 01 and a left case cover 08, and a small diameter gear Ollb of the reduction gear Oil is in mesh with a starting system gear 012 on a side of the crank shaft 02. [Problems to be Solved by the Invention] According to the example, the cylinder 04 is extended upwardly from the crank case at the front portion of the unit swing case 01 and accordingly space under a seat is significantly limited. In that case, when the cylinder is inclined forwardly to secure the space under the seat, there causes a problem of interference with a rear frame and when the unit swing case 01 is moved rearwardly to avoid the interference, the wheel base is prolonged. Further, when the starter motor 07 is arranged at the crank center C as described above, it is disposed at the same position as positions of the cylinder 04, an intake system mechanism, an exhaust system mechanism and the like in the case of the crank case lead valve type and accordingly, such mechanisms related to the basic functions of the internal combustion engine are restricted by the arrangement of the starter motor and the degree of freedom of layout is limited. Further, the starter motor 07 is a sufficient protecting structure against water and mud in running since it is attached outside of the unit swing case 01 and a number of parts such as 0-ring, parking, oil seal in motor and the like is increased. Further, when the starter motor is arranged on the lower side of the unit swing case 01, not only the waterproof structure must be made more strict but the bank angle of the motorcycle is influenced. In this case, although there has been disclosed an example (Japanese Examined Patent Publication No. JP-B-1-31036 ) where a starter motor is arranged in a unit swing case, according to the example, the power transmission system is of a chain type, an allowable space is provided between the crank shaft and the reduction mechanism on a rear side thereof and the starter motor is arranged in the space, which is different from the belt power transmission system. Further, according to the example, the drive shaft of the starter motor is directed substantially in the forward and backward direction and is not in parallel with the crank shaft and therefore, a number of parts is increased to change the power direction. The present invention has been carried out in view of such a point and it is an object of the present invention to provide a structure of attaching a starter motor of a unit swing type internal combustion engine whereby reduction of the wheel base is achieved while securing a large degree of freedom in respect of the space under the seat and a large degree of freedom is provided to the layout of mechanisms related to the basic functions of the internal combustion engine, [Means of Solving the Problem] According to the present invention there is provided a structure of attaching a starter motor of a unit swing type internal combustion engine in a motorcycle having a unit swing type internal combustion engine having a belt power transmission device and swingably supported by a vehicle body; wherein a cylinder which is inclined forwardly is extended from a crank case at a front portion of a unit swing case; wherein a duct to the cylinder is provided from a cooling fan provided on a side of said crank case to the same side of said cylinder; wherein a starter motor is placed on a side of said cylinder opposed to the side of said duct at a position overlapping said cylinder in a side view; wherein said cylinder is disposed between a pair of left and right rear frames both connected to a head pipe; characterized in that a starter motor is located ahead of a drive pulley composing the belt power transmission installed in an end of the crank shaft. The cylinder is extended from the crank case by being inclined forwardly and is disposed between the pair of left and right rear frames connected to the head pipe and therefore, the reduction of the wheel base can be achieved while securing the larger degree of freedom in respect of the space under the sea t . Further, the duct from the cooling fan is provided on one side of the cylinder disposed between the pair of left and right rear frames and the starter motor is arranged by utilizing a dead space overlapping the cylinder in a side view from the opposite side and therefore, not only the internal combustion engine is downsized but the degree of freedom of layout of the mechanisms related to the basic functions of the internal combustion engine is enlarged. According to the invention described in Claim 2 , there is provided the structure of attaching a starter motor of a unit swing type internal combustion engine according to Claim 1, wherein the starter motor is arranged in the unit swing case. The starter motor is sufficiently protected against water and mud in running by the unit swing case and the case cover without providing the starter motor with a separate and special waterproof structure. to the invention described in Claim 3, there is provided the structure of attaching a starter motor of a unit swing type internal combustion engine according to Claim 1 wherein the internal combustion engine is provided with an intake port on an upper face of the crank case at an outer periphery of a crank web, and wherein an engine hanger is provided between the intake port and the cylinder. The intake port is provided on the upper face of the crank case, an intake pipe is extended from the intake port, the engine hanger is provided between the intake port and the cylinder inclined forwardly and either of them is arranged compactly in the space above the crank case whereby the internal combustion engine can be downsized and the lowest height above the ground can be secured. Further, the engine hanger is disposed on the rear side of the cylinder disposed between the pair of left and right rear frames and the degree of freedom of a link connecting the rear frames with the engine hanger is enlarged. According to the invention described in Claim 4, there is provided the structure of attaching a starter motor of a unit swing type internal combustion engine according to Claim 1 wherein a reduction gear mechanism is provided between the starter motor and a crank shaft, and wherein a bearing unit of the reduction gear mechanism is disposed at a shoulder of a scavenging path provided to the crank case. The bearing unit of the reduction gear mechanism is disposed at the shoulder to avoid the scavenging path and therefore, the starter motor can be arranged proximate to the center of the cylinder along with the reduction gear mechanism and accordingly, the width of the internal combustion engine in the left and the right direction can be shortened, the interval between the pair of the left and right rear frames on both sides of the cylinder can be narrowed and the downsizing of the vehicle body can be achieved. According to the invention described in Claim 5, there is provided the structure of attaching a starter motor of a unit swing type internal combustion engine according to any one of Claim 1 through Claim 3 wherein the starter motor is arranged on the side of the cylinder and on a side lower than a center line of the cylinder, and wherein a warm air duct to a carburetor is provided on the same side of the cylinder and on a side upper than the center line of the cylinder. On the one side of the cylinder, the starter motor is arranged on the lower side of the center line of the cylinder and the warm air duct passes on the upper side thereof by which the warm air duct can be arranged compactly along with the starter motor and the downsizing of the power unit can be achieved while securing the warm air duct. [BRIEF EXPLANATION OF THE DRAWINGS] [Fig. 1] Fig. 1 is a side view of a scooter type motorcycle 1 having a unit swing type internal combustion engine according to an embodiment of the present invention. [Fig. 2] Fig. 2 is a partially cut upper view of a link portion connecting a swing unit to a vehicle body frame. [Fig. 3] Fig. 3 is a sectional view cut substantially along a line III - III of Fig. 1. [Fig. 4] Fig. 4 is a sectional view cut along a center line of a cylinder of an internal combustion engine. [Fig. 5} Fig. 5 is a side view of a swing unit where a transmission case cover is removed. [Fig. 6] Fig. 6 is an upper view of a front portion of the swing unit. [Fig. 7] Fig. 7 is a side view of the unit swing case. [Fig. 8] Fig. 8 is a sectional view cut along a line VIII - VIII of Fig. 7 . [Fig. 9] Fig. 9 is a side view of a shroud. [Fig. 10] Fig. 10 is a side view of a warm air duct. [Fig. 11] Fig. 11 is an upper view thereof. [Fig. 12] Fig. 12 is a sectional view of essential portions of a swing unit according to other embodiment. [Fig. 13] Fig. 13 is a sectional view showing a structure of attaching and arranging a conventional starter motor. [Fig, 14] Fig. 14 is a sectional view cut along a line XIV - XIV of Fig. 13. [Working Examples] An explanation will be given of an embodiment of the present invention in reference to Figs. 1 through 11. Fig. 1 is a side view of a scooter type motorcycle having a unit swing type internal combustion engine according to the present invent ion. A vehicle body front portion 2 and a vehicle body rear portion 3 are connected via a low floor portion 4 and a vehicle body frame 5 constituting the skeleton structure of the vehicle body comprises a front frame 5a falling at the front portion of the vehicle body, a pair of left and right horizontal frames 5b divided in two at the lower end of the front frame 5a and extending rearwardly at the lower portion of the floor portion 4 and a pair of left and right rear frames 5c rising from the respective rear portions of the horizontal frames 5b and extending in an oblique rearward direction. A seat 6 is provided above the rear frame 5c of the vehicle body rear portion 3 and a containing box 7 is arranged on the lower side of the seat 6. A steering head 9 having a handle 8 at an upper portion thereof is provided at the vehicle body front portion 2 and a front wheel 11 is suspended at a lower side thereof via a front fork 10 which is directed by the handle 8. Further, the pair of left and right rear frames 5c of the vehicle body frame 5 rises in a steep inclination to an oblique upward direction and is extended rearwardly in a moderate inclination after being bent and a pivoting shaft 13 suspended between brackets 12 respectively fixed to the left and the right bent portions and a pair of left and right hanger brackets 17 projected at the upper face of the front portion of a unit swing case 16 of a swing unit 15, are connected by a link member 14. As illustrated in Figs. 2 and 4, the link member 14 is constituted by connecting a front end sleeve 14a and a rear end pivot shaft 14b by connecting portions 14c, the front sleeve 14a is axially supported by the pivoting shaft 13 on the side of the vehicle body frame via press-fit rubber bushes 13a and the rear end pivot shaft 14b axially supports the pair of hanger brackets 17 on the side of the swing unit 15 via rubber bushes 17a. Further, a projection piece 14d is projected forwardly from the central position of the front end sleeve 14a, meanwhile, a cabinet 5e is fixed to the center of a cross member 5d suspended between the rear frames 5c, a rubber elastic body 5f is fittingly mounted into the cabinet 5e, and a front half portion of the projection piece 14d projected from the front end sleeve 14a is fitted to the rubber elastic body 5f . Therefore, pivoting of the link member 14 axially supported by the pivoting shaft 13 is regulated by the vehicle body frame 5 elastically via the rubber elastic body 5f . The swing unit 15 is made swingable in the upward and downward direction by supporting the front upper portion thereof by the rear frames 5c via the link member 14 and a rear cushion 19 is interposed between the swing unit 15 and the vehicle body frame 5 rearward from the link member 14. A crank case 16a is constituted and an internal combustion engine 20 is integrally provided at the front portion of the unit swing case 16 of the swing unit 15, a rear wheel 21 is axially supported at a rear portion thereof and power of the internal combustion engine 20 is transmitted to the rear wheel 21 by a belt transmission mechanism 22 having an automatic speed changing function. A fuel tank 23 is mounted by being fixed to suspend between the horizontal frames 5b of the floor portion 4 . The internal combustion engine 20 is a 2-cycle internal combustion engine in which a cylinder 25 is extended forwardly from the crank case 16a by being inclined forwardly substantially horizontally and the cylinder 25 is disposed at a position penetrating the steep inclined portions of the pair of left and right rear frames 5c. Further, the crank case lead valve type where a lead valve is provided at the crank case, is adopted in the internal combustion engine 20, referring to Fig. 4, an intake port 16g is formed at the outer periphery of a crank web 36b and on the upper face of the crank case 16a, a lead valve is fittingly mounted to the intake port, an intake pipe 27 is extended from the intake port 16g and is connected to a carburetor 28, and as shown in Fig. 1, an air cleaner 29 mounted to a rear portion of the unit swing case 16 is connected to the carburetor 28 whereby air is introduced. As illustrated by Figs. 4 through 6, the intake pipe 27 is extended to the upward oblique direction on the left side from the intake port 16g formed at the central position on the upper face of the crank case 16a and is extended rearwardly after being bent and connected to the carburetor 28 via a connection flange 27a. Further, in the crank case 16a, the intake port 16g is provided at the central position on the upper face, the cylinder 25 is extended forwardly, and the pair of hanger brackets 17 are projected upwardly at left and right positions between the intake port 16g and the cylinder 25. An exhaust pipe 30 extended downwardly from the lower portion of the cylinder 25 of the internal combustion engine 20, detours the lover side of the crank case 16a rearwardly and to the right side and is connected to a muffler 31 arranged on the right side of the vehicle body (refer to Fig. 1) . Further, a stand 33 is pivotably attached to a front end of a bracket 32 provided at the rear end of the horizontal frame 5b of the floor portion 4 and at a rise portion of the rear frame 5c . Fig. 3 is a sectional view of the swing unit 15 cut and developed substantially along a line III - III of Fig. 1 although there are partially different portions. The unit swing case 16 is divided into a left side unit case 16L and a right side unit case 16R at the front side crank case 16a and the both cases 16L and 16R are fastened by a bolt 35. The front portion of the unit swing case 16 corresponds to the crank case 16a and cylinder 25 is extended forwardly at the front portion. A crank shaft 36 is extended in the left and right direction in the crank case 16a by being rotatably supported by a main bearing 37R mounted to the right case 16R and a main bearing 37L mounted to the left side unit case 16L and both ends thereof are projected outwardly from the crank case 16a. A piston 24 reciprocating in a cylinder bore 25a of the cylinder 25 and a crank pin 36a of the crank shaft 36 are connected by a connecting rod 34. Referring to Figs. 3 and 4, an exhaust port 25b and a scavenge port 25c which are opened and closed by the piston 24 are provided to the cylinder bore 25a, the exhaust port 25b is disposed on the lower side and is connected to the exhaust pipe 30, and the scavenge port 25c is disposed on the left and the right and the upper side and is communicated with the scavenging path 25d. In the upward stroke of the piston 24, the lead valve 26 is opened by a negative pressure caused in the crank case 16a and the mixture gas is sucked from the carburetor 28 into the crank case 16a, compressed in the downward stroke of the piston 24 and is supplied to the combustion side cylinder bore 25a from the scavenge port 25c via the scavenging path 25d. Meanwhile, a generator 38 and a cooling fan 39 are attached to the right end portion of the crank shaft 36, a drive pulley 40 of the belt transmission mechanism 22 is attached to the left end and a starter one way clutch 41 is provided on the right side of the drive pulley 39. The starter one way clutch 41 is a roller type one way clutch in which a starter driven gear 42 integrally forms an inner ring 42a, meanwhile, an outer ring 44 integral with the crank shaft 36 which is rotated relatively in respect of the inner ring 42a via a bearing 43, forms a cam face at an inner peripheral face thereof and rollers 45 are interposed between the outer ring 44 and the inner ring 42a (refer to Fig. 3) . In respect of the left side unit case 16L, a transmission case wall 16b is extended rearwardly from the crank case 16a, the left side open face is covered by a transmission case cover 47 via a packing 46, the belt transmission mechanism 22 is contained at the inside, rotation of the crank shaft 36 is transmitted to a driven shaft 51 via the drive pulley 40, a V belt 48, a driven pulley 45, and a clutch 50, and rotation of the driven shaft 51 is further transmitted to a rear wheel shaft 53 at the rear end via a reduction gear device 52 . In respect of the left side unit case 16L of the unit swing case 16 which is prolonged in the front and rear direction and where the transmission case wall 16b is extended rearwardly from the crank case 16a as described above, as illustrated by Figs. 3, 7 and 8, an outer peripheral wall 16c surrounds the surrounding of the left side opening, the end face of the outer peripheral wall 16c constitutes a match face 16d, and bolt boss portions 16e are formed to project outwardly at portions of the outer peripheral wall 16c. Referring to Fig. 7, in respect of the crank case 16a of the left side unit case 16L, a circular space 61 for incorporating the starter one way clutch 41 is formed by a side wall 60 developed in a circular shape centering on a circular hole to which the main bearing 37L supporting the crank shaft 36 is fitted and a peripheral wall thereof, a circular recess 63 for containing a reduction gear 96 is formed on a rather oblique lower side forward therefrom and a bearing hole 63a is provided at the central portion of the circular recess 63. An expanded recess portion 64 where a portion of the circular recess 63 is expanded forwardly in substantially a semicircular shape is formed and a drive shaft 83 of a starter motor 80 is disposed at the expanded recess portion 64 . Accordingly, the starter motor 80 per se is installed at a position overlapping the cylinder 25 in a side view as shown in Fig. 5, disposed on the inner side of the unit swing case 16 and is covered by the transmission case cover 47. The starter motor 80 is covered by the transmission case cover 47 and therefore, the starter motor 80 per se does not need to be of a waterproof structure and is sufficiently protected against water and mud in running. In respect of the starter motor 80, as shown in Fig. 3, an inner rotor 82 is rotatably supported at the inside of a cylindrical outer 81 centering on the drive shaft 83, a motor bracket 85 is integrally fixed on the outer opening side to which the drive shaft 83 is projected, and the motor bracket 85 is fixedly screwed to the left side unit case 16L by bolts 86 by which the starter motor 80 is attached to the inside of the unit swing case 16. A drive gear 83a is formed at a portion of the drive shaft 83 projected outwardly from the motor bracket 85. Both ends of a reduction gear shaft 95 are respectively fitted to the bearing hole 63a of the left side unit case 16L and a bearing hole of the motor bracket 85 opposed thereto and the reduction gear 96 is rotatably supported between the both fitted portions via a bearing bush 97 (refer to Fig. 3) . The reduction gear 96 is constituted coaxially and integrally by a large diameter gear 96a and a small diameter gear 96b. The small diameter gear 96b is in mesh with the starter driven gear 42 of the starter one way clutch 41 fitted to the crank shaft 36 and the large diameter gear 96a is in mesh with the drive gear 83a of the drive shaft 83 of the starter motor 80. Accordingly, the drive of the starter motor 80 is transmitted to the crank shaft 36 via the reduction gear 96 and the starter one way clutch 41. for starting the internal combustion engine 20. As shown in Fig. 8, the bearing hole 63a to which the reduction gear shaft 95 of the reduction gear 96 is fitted, is disposed at a shoulder on the left side (right side in Fig. 8) below the scavenging path 25d of the cylinder 25 by which the reduction gear 96 can be arranged proximate to the center of the cylinder 25 without projecting downwardly whereby a total of the internal combustion engine can be downsized. The cylinder 25 is covered with a shroud 101, the right opening of the shroud 101 is connected to the fan cover 102 covering the cooling fan 39 (refer to Fig. 3), and air sucked by rotating the cooling fan 39 is introduced to the cylinder 25 for cooling the cylinder 25. Meanwhile, as shown in Figs. 3 and 9, a connection tube lOla having a square section is rather projected leftwardly at a left side wall of the shroud 101 and a pair of upper and lower projections lOlb are formed at a front wall of the connection tube lOla. Further, a warm air duct 103 is connected to the connection tube lOla. As shown in Figs. 10 and 11, the warm air duct 103 is a pipe having a flat rectangular section and elongated in the forward and rearward direction, a rectangular opening frame 103a is formed on the right by enlarging the inside of the pipe by a small amount at the front end portion and a pair of upper and lower engagement pieces 104 are projected to the right direction at a front wall thereof. Small holes 104a are perforated in the engagement pieces 104. The warm air duct 103 is extended rearwardly from the front end portion in an oblique upward direction while being bent, an exhaust port 103b is formed at the rear end, a pin 105 is projected in the left direction on the left side face at the middle of the elongated warm air duct 103, and a pin receiving member 106 is fixed on the right side face of the rear portion. The pin receiving member 106 is a rectangular small piece and an engagement groove 106a is formed to open to one side thereof. Meanwhile, in respect of the hanger bracket 17 projected from the upper face of the crank case 16a of the unit swing case 16, the bearing rubber bush 17a for axially supporting the pivot shaft 14b is fitted to the upper portion and a circular hole 17b is formed at a predetermined portion of the side wall therebelow (refer to Figs. 7 and 8). Further, a pin 107 is projected in the left direction from the connection flange 27a for connecting the intake pipe 27 extended from the intake port 16g and a carburetor 28. In attaching the warm air duct 103, firstly, the warm air duct 103 is passed through an interval between the pivot shaft 14b and the crank case 16a along the inner side (right side) of the left side hanger bracket 17, the square opening frame 103a at the front end is made to coincide with the connection pipe lOla of the shroud 101, the projections lOlb of the front wall of the connection pipe lOla are engaged to fit to the small holes 104a of the pair of upper and lower engagement pieces 104, the pin 105 projected from the left side face of the warm air duct 103 is fitted to the circular hole 17b of the side wall of the hanger bracket 17 and successively, the pin 107 projected from the connection flange 27a of the intake pipe 27 is engaged with the engagement groove 106a of the pin receiving member 106 on the right side face of the rear portion of the warm air duct 103 (refer to Figs. 5 and 6) . As described above, the warm air duct 103 is firmly attached to the unit swing case 16 by connecting to make the square opening frame 103a at the front end to coincide with the connection pipe lOla of the shroud 101, positioning the front end by engaging the engagement pieces 104 to the projections lOlb, positioning the middle portion in the forward and rearward direction by engaging the pin 105 to the circular hole 17b by which the left side fare is held by the hanger bracket 17, and fixing the rear portion by engaging the pin receiving member 106 to the pin 107 whereby the right side face is held . According to the embodiment, although the operational efficiency is improved without using screws or the like in attaching the warm air duct 103, screws or the like may naturally be used. When the warm air duct 103 is attached in this way, air warmed by the cylinder 25 can be introduced to the warm air duct 103, can be exhausted from the exhaust port 103b at the rear end, and can be blown to the carburetor 28 arranged opposedly to the exhaust port 103b. By blowing warm air to the carburetor 28 cooled by the heat of vaporization in driving the internal combustion engine 20, the vaporizing function can be maintained by maintaining the temperature at a certain degree or higher and a so-called icing or the like can be prevented from occurring in cold areas. As shown in Fig. 5, on the left side of the cylinder 25, the starter motor 80 is arranged on the lower side of the cylinder center line C-C to overlap the cylinder 25 in a side view and the warm air duct 103 is arranged by utilizing the space on the upper side of the cylinder center line C-C thereabove whereby the swing unit 15 can be downsized while securing the warm air path to the carburetor 28. On the right side of the cylinder 25, the fan cover 102 for forming the duct to the cylinder 25 is provided and the starter motor 80 is arranged in the dead space overlapping the cylinder 25 on the opposite left side in a side view and therefore, the degree of freedom of layout of the mechanisms related to the basic functions of the internal combustion engine is enhanced and further, the swing unit 15 can be downsized by utilizing effectively the space without projecting the starter motor 80 to the lower portion of the swing unit 15. The cylinder 25 is disposed between the rear frames 5c by being inclined forwardly substantially horizontally and therefore, the space under the seat 6 can be secured, the volume of the containing box 7 can be increased and the wheel base can be shortened . Further, the hanger bracket 17 is arranged to project upwardly by utilizing space between the intake port 16g on the upper face of the crank case 16a and the cylinder 25 inclined forwardly and therefore, compact formation of the internal combustion engine 20 is achieved and the degree of freedom of the link member 14 in view of the relationship with the rear frames 5c is promoted. Further, the hanger bracket 17 is not projected downwardly and therefore, also the minimum height of the ground can be secured. Although according to the above-described embodiment, the drive of the starter motor 80 is transmitted to the crank shaft 36 via the reduction gear 96 and the starter one way clutch 41 thereby starting the internal combustion engine 20, an explanation will be given of an example of another drive transmission mechanism in reference to Fig. 12 as follows . A starter motor 110 is fixed to a unit swing case 120 at a position overlapping a cylinder 121 in a side view substantially the same as in the starter motor 80 from the left side via a motor bracket 111 by volts 112. Further, a starter pinion 115 is arranged to be disposed at a shoulder portion below a scavenge path 121d of the cylinder 121, which is substantially the same as the position of arranging the above-described reduction gear 96. In respect of the starter pinion 115, one end of pinion shaft thereof is fitted to and supported by a bearing hole at the motor bracket 111 and the other end thereof is fitted to and supported by a bearing hole 120a at the shoulder portion below the scavenge path 121d of the unit swing case 120. In respect of the starter pinion 115, an input side gear 116 is in mesh with a drive gear llOa formed at the drive shaft of the starter motor 110 and an output side gear 117 is rotated by jumping out the axial direction in driving thereof. A driven gear 118 is integrally fitted to a crank shaft 122 at a position in mesh with the jumped output side gear 117. Accordingly, the driven gear 118 is not in mesh with the output side gear 117 except in starting the internal combustion engine and when the starter motor 110 is driven in starting the engine, the output side gear 117 of the starter pinion 115 jumps out and becomes in mesh with the driven gear 118 thereby starting the engine by rotating the crank shaft 122. According to the embodiment, the starter one way clutch 41 and the like in the above-described embodiment are not necessary. Incidentally, although the starter pinion 115 becomes larger than the reduction gear 96, since the starter pinion is disposed at the shoulder portion below the scavenge path 121d of the cylinder 121, the starter pinion can be arranged proximate to the center line C-C of the cylinder 121 and accordingly, the starter motor 110 can be prevented from projecting to the left side direction and the downsizing of the swing unit can be maintained. (Explanation of Notation] 1. .scooter type motorcycle. 2. . .vehicle body front portion. 3. ..vehicle body rear portion. 4. ..floor portion, 5...vehicle body frame, 6...seat, 7 ... containing box, 8...handle, 9 ... steering head, 10...front fork, 11...front wheel, 12...bracket, 13...pivoting shaft, 14...link member, 15. . . swing unit, 16. . .unit swing case, 17. . .hanger bracket, 19...rear cushion, 20 ... internal combustion engine, 21...rear wheel, 22...belt transmission mechanism, 23...fuel tank, 24. ..piston, 25 ... cylinder, 26. ..lead valve, 27. ..intake pipe, 28 ... carburetor, 29. ..air cleaner, 30...exhaust pipe, 31...muffler, 32 ... bracket, 33...stand, 34 ... connecting rod, 36...crank shaft, 37...main bearing, 38 ... generator, 39...cooling fan, 40...drive pulley, 41...starter one way clutch, 42...starter driven gear, 43...bearing, 44 ... outer wheel, 45. ..roller, 46 ... packing, 47 ... transmission case cover, 48...V belt, 49...driven pulley, 50...clutch, 51...driven shaft, 52 ... reduction gear device, 53...rear wheel, 60 ... side wall, 61 ... circular space , 63 . . . circular recess, 64...projected recess 80...starter motor, 81... cylindrical outer, 82...inner rotor, 83 ...drive shaft, 85...motor bracket, 86...bolt 95. . .reduction gear shaft, 96. . .reduction gear, 97...bearing bush 101 ... shroud, 102 ... fan cover, 103 ... warm air duct, 104 ... engagement piece, 105...pin, 106...pin receiving member, 107...pin 110 ... starter motor, 111...motor bracket, 112...bolt, 115...starter pinion, 116...input side gear, 117...output side gear, 118... driven gear, 120...unit swing case, 121...cylinder, 122...crank shaft. WE CLAIM :- 1. A structure of attaching a starter motor of a unit swing type internal combustion engine in a motorcycle having a unit swing type internal combustion engine having a belt power transmission device and swingably supported by a vehicle body; wherein a cylinder which is inclined forwardly is extended from a crank case at a front portion of a unit swing case; wherein a duct to the cylinder is provided from a cooling fan provided on a side of said crank case to the same side of said cylinder; wherein a starter motor is placed on a side of said cylinder opposed to the side of said duct at a position overlapping said cylinder in a side view; wherein said cylinder is disposed between a pair of left and right rear frames both connected to a head pipe; characterized in that a starter motor is located ahead of a drive pulley composing the belt power transmission installed in an end of the crank shaft. 2. A structure of attaching a starter motor of a unit swing type internal combustion engine as claimed in claim 1 wherein said starter motor is located in said unit swing case. 3. A structure of attaching a starter motor of a unit swing type internal combustion engine as claimed in claim 1: wherein a reduction gear mechanism is provided between said starter motor and a crank shaft; and wherein a bearing unit of said reduction gear mechanism is disposed at a shoulder of a scavenging path provided to said crank case. 4. A structure of attaching a starter motor of a unit swing type internal combustion engine as claimed in any one of claim 1 to claim 3: wherein said starter motor is located on the side of said cylinder and on a side lower than a center line of said cylinder; and wherein a warm air duct to the carburetor is provided on the same side of said cylinder and on a side upper than the center line of said cylinder. 5. A structure of attaching a starter motor of a unit swing type internal combustion engine substantially as hereinbefore described with reference to the accompanying drawings.

Documents:

64-del-1998-abstract.pdf

64-del-1998-claims.pdf

64-del-1998-correspondence-others.pdf

64-del-1998-correspondence-po.pdf

64-del-1998-description (complete).pdf

64-del-1998-form-1.pdf

64-del-1998-form-13.pdf

64-del-1998-form-19.pdf

64-del-1998-form-2.pdf

64-del-1998-form-3.pdf

64-del-1998-form-4.pdf

64-del-1998-form-6.pdf

64-del-1998-gpa.pdf

64-del-1998-petition-137.pdf

64-del-1998-petition-138.pdf