Title of Invention	"ARRANGEMENT STRUCTURE OF BEARINGS"
Abstract	An arrangement structure for bearings comprising a plurality of power transmission shafts (60) positioned in a substantially parallel arrangement relative to each other, the power transmission shafts (60) being rotatably supported via bearings, respectively, and arranged so that the bearings overlap partly with each other in an axial view and a wall portion (59C) for supporting the respective bearings is provided wherein the respective bearings are mounted to the wall portion (59C) substantially in the same direction.

Title of Invention

"ARRANGEMENT STRUCTURE OF BEARINGS"

Abstract

An arrangement structure for bearings comprising a plurality of power transmission shafts (60) positioned in a substantially parallel arrangement relative to each other, the power transmission shafts (60) being rotatably supported via bearings, respectively, and arranged so that the bearings overlap partly with each other in an axial view and a wall portion (59C) for supporting the respective bearings is provided wherein the respective bearings are mounted to the wall portion (59C) substantially in the same direction.

Full Text	The present invention relates to an arrangement of bearings for a plurality of torque transmission elements. [Background Art] Hitherto, there is proposed, for example, in Patent Document 1, an arrangement structure for bearings in which a plurality of power transmission shafts linked to each other are arranged in substantially parallel to each other for rotatably supporting the respective power transmission shafts via the bearings respectively. This technology has a structure in which the respective bearings are mounted to wall portions which, support the bearings from both sides, so that the respective bearings are partly overlapped when viewed in axial view. [Patent Document 1] Patent Publication No. 3039168 (Fig. 5) [Disclosure of the Invention] [Problems to be Solved by the Invention] However, in the arrangement structure of bearings as described above, although the center distance between the power transmission shafts can be reduced, since the bearings which 3-Xare overlapped with each other in axial view are mounted to the wall portion from the opposite directions, assembly of a unit including these bearings may take a lot of trouble. When considering maintenance of bearings or the like by disassembling the unit, since the structure of the wall portions is complicated, maintenance may take a lot of trouble. Accordingly the present invention provides an arrangement structure of bearings for improving assembleability and maintenanceability of the respective bearings which overlap in the axial direction. [Means for Solving the Problems] [0004] As a solving means of the above described subject, the invention as set forth in Claim 1 is an arrangement structure of bearings including a plurality of power transmission shafts (for example, a driven shaft 60, an intermediate shaft 73 in an embodiment) linked in substantially parallel to each other, the power transmission shafts being rotatably supported via bearings (for example, radial ball bearings 87, 88 in the embodiment) respectively and arranged so that the bearings are overlapped partly with each other in axial view, characterized in that a wall portion for supporting the respective bearings (for example, an inner wall portion 59C in the embodiment) is provided, and the respective bearings are mounted to the wall portion substantially in the same direction. [0005] In this structure, when assembling the unit including the respective bearings, the respective bearings may be mounted to the wall portion substantially in the same direction. Likewise, maintenance of the respective bearings can be performed substantially in the same direction. [0006] The invention as set forth in Claim 2 is characterized in that the wall portion is formed with a recess (for example, a storage section 95 in the embodiment) so that a first bearing (for example, the radial ball bearing 88 in the embodiment) of the bearings is disposed on the far side of a second bearing (for example, the radial ball bearing 87 in the embodiment) of the bearings in terms of the mounting direction of the respective bearings, the bearings being overlapped to each other in axial view. [0007] In this arrangement, when mounting the respective bearings to the wall portion, the first bearing is mounted to the wall portion in a state of being disposed within the recess to place on the far side in terms of mounting direction, and then the second bearing is mounted to the wall portion. [0008] The invention as set forth in Claim 3 is characterized in that a bearing holder (for example, a bearing holder 100 in the embodiment) for surrounding and retaining the second bearing, and the second bearing is mounted to the wall portion via the bearing holder. [0009] In this arrangement, the second bearing can be supported via the bearing holder over the entire perimeter. [0010] The invention as set forth in Claim 4 is characterized in that the first bearing is disposed between the second bearing and the wall portion in the axial direction. [0011] In this arrangement, the first bearing can be interposed between the second bearing and the wall portion. [0012] The invention as set forth in Claim 5 is characterized in that a space is formed the second bearing and the first bearing in the axial direction. [0013] In this arrangement, the part tolerance of the respective bearings in the axial direction and the mounting tolerance with respect to the wall portion can be absorbed. [Advantage of the Invention] [0014] According to the invention as set forth in Claim 1, assembleability and maintenanceability of the respective bearings can be improved. According to the invention as set forth in Claim 2, mounting of the respective bearings are facilitated, and assembleability thereof can further be improved. According to the invention as set forth in Claim 3, the mounting force of the second bearing with respect to the wall portion can be improved. According to the invention as set forth in Claim 4, the mounting force of the first bearing with respect to the wall portion can be improved. According to the invention as set forth in Claim 5, mounting accuracy of the respective bearings can be improved. [Best Mode for Carrying Out the Invention] Referring now to the drawings, embodiments of the present invention will be described. [Brief Description of the Drawings] [Fig. 1] Fig. 1 is a side view of a motorcycle according to an embodiment of the present invention. [Fig. 2] Fig. 2 is a block diagram showing a system structure of the motorcycle shown in Fig. 1. [Fig. 3] Fig. 3 is a cross-sectional view explanatory drawing of a power unit of the motorcycle shown in Fig. 1. [Fig. 4] Fig. 4 is an enlarged view of the periphery of a stepless speed changer in Fig. 3. [Fig. 5] Fig. 5 is an enlarged view of the periphery of a speed reduction mechanism in Fig. 3. [Fig. 6] Fig. 6 is a view of the periphery of a driven shaft and an intermediate shaft of the speed reduction mechanism when viewed in the direction indicated by an arrow F in Fig. 5. [Fig. 7] Fig. 7 is an enlarged view of a second embodiment of the present invention corresponding to Fig. 5. [Fig. 8] Fig. 8 is a view of the periphery of the driven shaft and the intermediate shaft in Fig. 7 when viewed in the direction of an arrow F'. Terms representing the directions such as front, rear, left and right correspond to the directions with respect to a vehicle. [First Embodiment] In Fig. 1, reference numeral lA designates a unit swing system motorcycle configured as a hybrid vehicle. The motorcycle 1A includes a front fork 1 which rotatably supports a front wheel WF at the front of the vehicle body. The front wheel WF and the front fork 1 are rotatably supported by a head pipe 2, so as to be capable of steering by the operation of a handle 3. A down pipe 4 is mounted to the head pipe 2 so as to extend rearward and downward, and an intermediate frame 5 is extending substantially horizontally from the lower end of the down pipe 4. [0017] A rear frame 6 is formed rearward and upward from the rear end of the intermediate frame 5. The front end of a power unit 11 including an engine 20 as a prime mover of the motorcycle 1A, described later, is rotatably attached to a vehicle body frame 10 configured as described above. The power unit 11 is, so-called, a unit swing system which swings in the vertical direction about the front end thereof, which is rotatably mounted to the vehicle body frame 10. A rear wheel WR, which is a drive wheel, is rotatably mounted to the rear end of the power unit 11. Mounted between the power unit 11 and the rear frame 6 is a rear cushion, not shown. [0018] The periphery of the vehicle body frame 10 is covered by a vehicle body cover 13, and a seat 14 on which a rider seats is disposed at the rear on the upper surface of the vehicle body cover 13. A step floor 15 on which the feet of the rider are placed is formed forwardly of the seat 14. A storage box 12 is provided below the seat 14, which is opened and closed by the seat 14 and is functioned as a utility space for storing, for example, a helmet, baggage, or the like. [0019] As shown in Fig. 2, the power unit 11 includes an engine 20, which is an internal combustion engine for generating an output by burning combustible air-fuel mixture, an ACG starter motor 2la which functions as a starter and a power generator, a stepless speed changer 23 connected to a crankshaft 22 of the engine 20 for transmitting a rotational power of the engine 20 to the rear wheel WR, a start-up clutch 40 for connecting and disconnecting power transmission between the crankshaft 22 and the input side of the stepless speed changer 23, a drive motor 21b which functions as a dynamotor or a power generator, a one-way clutch 44 which can transmit the rotational power only from the engine 20 and the drive motor 21b to the side of the rear wheel WR according to the input number of revolution, and a speed reduction mechanism 69 for reducing the speed of the rotational power from the stepless speed changer 23 and transmitting it to the rear wheel WR. [0020] The rotational power from the engine 20 is transmitted from the crankshaft 22 to the rear wheel WR via the startup clutch 40, the stepless speed changer 23, the one-way clutch 44, a driven shaft (power transmission shaft) 60 disposed on the output side of the stepless speed changer 23, and the speed reduction mechanism 69. On the other hand, the power from the drive motor 21b is transmitted to the rear wheel WR via the driven shaft 60, and the speed reduction mechanism 69. In other words, the driven shaft 60 which serves as a drive shaft of the rear wheel WR via the speed reduction mechanism 69 also corresponds to the output shaft of the drive motor 21b. [0021] A battery 74 is connected to the ACG starter motor 2la and the drive motor 2 Ib. The battery 74 supplies electric power to the motors 2la, 21b when the drive motor 21b functions as the dynamotor, and when the ACG starter motor 2la functions as the starter. When the ACG starter motor 2la and the drive motor 21b function as the power generators, regenerative electric power therefrom is charged. Control of the engine 20, the ACG starter motor 2la, and the drive motor 21b is performed a control unit 7 which is control means including a CPU (Central Processing Unit), a ROM (Read Only Memory) and a RAM (Random Access Memory) and so on. [0022] The engine 20 is configured to intake and burn air-fuel mixture including air and fuel from an air-intake pipe 16, and a throttle valve 17 for controlling the amount of air is rotatably provided in the air-intake pipe 16. The throttle valve 17 is rotated by the operating amount of a throttle grip, not shown, which is operated by the rider. Provided between the throttle valve 17 and the engine 20 are an injector 18 for injecting fuel and a negative pressure sensor 19 for detecting negative pressure in the air-intake pipe 16 (air-intake pipe negative pressure). [0023] As shown in Fig. 3, a piston 25 is connected to the crankshaft 22 of the engine 20 via a connecting rod 24, and the piston 25 is fitted into a cylinder 27 provided in a cylinder block 26. Then, by burning air-fuel mixture in a combustion chamber 20a defined by a cylinder head 28, the cylinder 27 and the piston 25, the piston 25 reciprocates in the cylinder 27 and the crankshaft 22 rotates to output the rotational power. Reference numeral 29 designates an ignition plug for igniting air-furl mixture. [0024] Opening and closing of a valve, not shown, for controlling intake or exhaust of air-fuel mixture to/from the combustion chamber 20a is performed by rotating a camshaft 30 supported by the cylinder head 28. A driven sprocket 31 is provided on the right end of the camshaft 30, and an endless cam chain 33 is wound around the driven sprocket 31 and the drive sprocket 32 provided on the right end of the crankshaft 22 . A water pump 34 is provided on the camshaft 30 on the right side of the driven sprocket 31, and the water pump 34 works as the camshaft 30 rotates. [0025] A stator case 49 is connected to the right side of a crankcase 48 which supports the crankshaft 22, and the ACG starter motor 21a is stored within the stator case 49. The ACG starter motor 2la is a motor of so-called an outer rotor system, and the stator is a coil 51 formed by winding a conductor wire wired on a teeth 50 fixed to the stator case 49. An outer rotor 52 has substantially cylindrical shape covering the outer periphery of the stator, and is provided with a magnet 53 on the inner peripheral surface thereof. The outer rotor 52 is coaxially fixed to the crankshaft 22. A fan 54a for cooling the ACG starter motor 2la is mounted to the left side of the outer rotor 52. [0026] A power transmission case 59 which extends toward the rear wheel WR is connected to the left side of the crankcase 48. The power transmission case 59 can be divided into a case body 59A which constitutes an inside (right side) portion thereof in terms of the vehicle width direction and a cover 59B to be mounted from the outside (left side) of the case body 59A in terms of the vehicle width direction. In a space 59K defined therein, a fan 54b fixed to the left end of the crankshaft 22, the start-up clutch 40, the stepless speed changer 23 connected at the input side thereof to the crankshaft 22 via the start-up clutch 40, and the drive motor 21b connected to the output side of the stepless speed changer 23 are stored. [0027] A cooling air intake port 59a is formed on the front left side of the power transmission case 59 in the vicinity of the fan 54b. When the fan 54b is rotated synchronously with the crankshaft 22, outside air is taken from the cooling air intake port 59a into the power transmission case 59, so that the drive motor 21b and the stepless speed changer 23 are cooled compulsorily. [0028] The stepless speed changer 23 is configured as, so-called, a belt converter including a drive side power transmission pulley 58, which is the input side to be mounted to the left end of the crankshaft 22 projected leftward from the crankcase 48 in terms of the vehicle width direction via the start-up clutch 40, a driven side power transmission pulley 62, which is the output side to be mounted to a driven shaft 60 supported by the power transmission case 59 along the axis in parallel with the crankshaft 22 via the one-way clutch 44, and an endless V-belt (endless belt) 63 wound on these pulleys 58, 62 so as to interconnect there between. The driven shaft 60 is provided so as to penetrate through the drive motor 21b and the driven side power transmission pulley 62, and the driven shaft 60 is rotatably supported by a gear case 70, in which the power transmission case 59 and the speed reduction mechanism 69 are stored. [0029] Referring also to Fig. 4, the drive side power transmission pulley 58 is mounted to the crankshaft 22 via a sleeve 58d through which the crankshaft 22 is penetrated so as to be capable of rotating in the circumferential direction, and includes a drive side fixed pulley half 58a secured on the sleeve 58d, and a drive side movable pulley half 58c, which is disposed on the outside (right side) of the drive side fixed pulley half 58a in terms of the vehicle width direction, and is mounted so as to be capable of sliding axial with respect to the sleeve 58d but not to be capable of rotating in the circumferential direction. The drive side fixed pulley half 58a and the drive side movable pulley half 58c are substantially bowl shape. The drive side fixed pulley half 58a is disposed so that the outer peripheral side thereof is positioned inside (left side) of the inner peripheral side in the vehicle width direction, and the drive side movable pulley half 58c is disposed so that the outer peripheral side thereof is positioned on the outside (left side) of the inner peripheral side in terms of the vehicle width direction. [0030] On the other hand, the driven side power transmission pulley 62 is mounted to the driven shaft 60 passing there through so as to be capable of rotating in the circumferential direction, and includes a driven side fixed pulley half 62a which is restrained in sliding movement with respect to the driven shaft 60 in the axial direction thereof, and a driven side movable pulley half 62b mounted on a boss 62c through which the driven shaft 60 of the driven side fixed pulley half 62a is passed so as to be capable of sliding movement in the axial direction thereof. The driven side fixed pulley half 62a and the driven side movable pulley half 62b are also substantially bowl shape. The driven side fixed pulley half 62a is disposed so that the outer peripheral side thereof is positioned inside (left side) of the inner peripheral side in terms of the vehicle width direction, and the driven side movable pulley half 62b is disposed so that the outer peripheral side is positioned outside (left side) of the inner peripheral side in terms of the vehicle width direction. [0031] The endless V-belt 63 is wound around belt grooves of V-shape in cross section, which are formed between the drive side fixed pulley half 58a and the drive side movable pulley half 58c, and between the driven side fixed pulley half 62a and the driven side movable pulley half 62b, respectively. [0032] A weight roller 58b is disposed inside the bowl shape of the drive side movable pulley half, that is, on the right side. Centrifugal force generated by the rotation of the drive side power transmission pulley 58 is exerted to the weight roller 58b, and then moves the weight roller 58b to the outer peripheral side of the drive side power transmission pulley 58, so that the drive side movable pulley half 58c slides toward the drive side fixed pulley half 58a. On the other hand, a spring 64 is provided on the left side of the driven side movable pulley half 62b/ and the driven side movable pulley half 62b is constantly urged toward the driven side fixed pulley half 62a by a resilient force of the spring 64. [0033] In this arrangement, when the number of revolution of the crankshaft 22 increases, the centrifugal force exerted on the weight roller 58b in creases on the drive side power transmission pulley 58, and hence the drive side movable pulley half 58c slides toward the drive side fixed pulley half 58a. The drive side movable pulley half 58c moves closer to the drive side fixed pulley half 58a by the amount of this sliding movement, and the width of the groove of the drive side power transmission pulley 58 is decreased. Consequently, the contact position between the drive side power transmission pulley 58 and the V-belt 63 is shifted radially outwardly of the drive side power transmission pulley 58, whereby the winding diameter of the V-belt 63 is increased. Accordingly, the width of the groove on the driven side power transmission pulley 62 formed by the driven side fixed pulley half 62a and the driven side movable pulley half 62b is increased. In other words, the winding diameter (diameter of transmission pitch) of the V-belt 63 is continuously changed according to the number of revolution of the crankshaft 22, and the gear-change ratio is changed automatically and steplessly. [0034] The start-up clutch 40 includes a cup-shaped outer case 40a secured to the sleeve 58d, an outer plate 40b secured to the left end of the crankshaft 22, a shoe 40d attached to the outer edge of the outer plate 4Ob via a weight 40c so as to face radially outwardly, and a spring 40e for urging the shoe 40d radially inwardly. The start-up clutch 40 is disposed outside (left side in this embodiment) of the stepless speed changer 23 in terms of vehicle width direction, between the drive side fixed pulley half 58a and the fan 54b, and in the vicinity of the cooling air intake port 59a formed on the power transmission case 59. [0035] In this arrangement/ when the number of revolution of the engine 20, that is, the number of revolution of the crankshaft 22 is egual to or smaller than a predetermined value (3000 rpm for example, which exceeds the number of revolution for idling) , the start-up clutch 40 blocks power transmission between the crankshaft 22 and the stepless speed changer 23, while when the number of revolution of the engine 20 exceeds the predetermined value, the centrifugal force exerted to the weight 40c works against an urging force of the spring 40e which works radially inwardly and hence the weight 40c moves radially outwardly, whereby the shoe 40d presses the inner peripheral surface of the outer case 40a by a force larger than the predetermined value and the crankshaft 22 is connected to the sleeve 58d via the start-up clutch 40. Accordingly, the rotational power of the crankshaft 22 is transmitted to the sleeve 58d via the start-up clutch 40, whereby the drive side power transmission pulley 58 fixed to the sleeve 58d is driven. [0036] The one-way clutch 44 includes a cup-shaped outer clutch 44a, an inner clutch 44b inserted into the outer clutch 44a coaxially, and a roller 44c which enables transmission of a power only in one direction from the inner clutch 44b to the outer clutch 44a. The outer clutch 44a serves also as the inner rotor body of the drive motor 21b, and is configured of the same material as the inner rotor body. Then, the inner periphery of the boss of the inner rotor body and the outer periphery of the driven shaft 60 which serves as the drive shaft of the rear wheel WR are spline fitted via the speed reduction mechanism 69, and the inner periphery of the inner clutch 44b and the left end of the boss 62c of the driven side fixed pulley half 62a are spline fitted. [0037] In this arrangement, a power from the engine 20 transmitted to the driven side power transmission pulley 62 of the stepless speed changer 23 is transmitted to the rear wheel WR via the driven side fixed pulley half 62a, the inner clutch 44b, the outer clutch 44a, that is, the inner rotor body, the driven shaft 60, and the speed reduction mechanism 69, while a power from the rear wheel WR side generated when the rider pushes the vehicle manually or during regenerative operation is transmitted to the speed reduction mechanism 69, the driven shaft 60, the inner rotor body, that is, the outer clutch 44a. However, since the outer clutch 44a runs idle with respect to the inner clutch 44b, such power is not transmitted to the stepless speed changer 23 and the engine 20. [0038] The drive motor 21b is provided in such a manner that the driven shaft 60 disposed in parallel with the vehicle width direction serves as a motor output shaft on the rear side of the power transmission case 59. In other words, in the drive motor 21b, the driven shaft 60, which is an input shaft to the speed reduction mechanism 69, serves also as a motor output shaft. It is for reducing the speed of the power from the drive motor 21b by the speed reduction mechanism 69 provided generally between the stepless speed changer 23 and the rear wheel WR and transmitting the same to the rear wheel WR. Accordingly, in comparison with the power unit which is not provided with the speed reduction mechanism 69 between the stepless speed changer 23 and the rear wheel WR and is directly connected to the motor, increase in number of components due to provide the speed reduction mechanism additionally can be prevented, or the drive motor 21b can be downsized. [0039] An inner rotor 80 includes an inner rotor body which is formed into cup shape and is spline fitted to the driven shaft 60 at a boss 80b formed at the center thereof, that is, the inner clutch 44b, and a magnet 80c disposed on the outer peripheral surface of the opening side of the inner clutch 44b. On the other hand, a stator 83 is configured by a coil 83c formed by winding a conductor wire on a teeth 83b fixed to a stator case 83a in the power transmission case 59. In this arrangement, the drive motor 21b functions as a dynamotor when assisting the output of the engine 20, and in addition, serves also as a power generator (generator) which converts the rotation of the driven shaft 60 into the electric energy and performs regenerative charging to the battery 74. [0040] The speed reduction mechanism 69 is provided in a gear case 70 which continues from the power transmission case 59 on the right side of the rear end thereof. The speed reduction mechanism 69 is provided with an intermediate shaft (power transmission shaft) 73 which is supported in parallel with the driven shaft 60 and an axle 68 of the rear wheel WR. The driven shaft 60 and the intermediate shaft 73 are connected by a first speed reduction gear pair 71, and the intermediate shaft 73 and the axle 68 are connected by a second speed reduction gear pair 72. In this arrangement, the rotational power of the driven shaft 60 is transmitted to the axle 68 after having reduced in speed at a predetermined speed reduction ratio via the first speed reduction gear pair 71 and the second speed reduction gear pair 72, whereby the rear wheel WR is driven so as to cause the motorcycle 1A to be started and traveled. [0041] In the hybrid vehicle with the arrangement as described above, when starting the engine, the crankshaft 22 is rotated by the use of the ACG starter motor 2la on the crankshaft 22. At this time, the start-up clutch 40 is not connected, and power transmission from the crankshaft 22 to the stepless speed changer 23 is blocked. Then, air-fuel mixture taken into the cylinder 27 synchronously with the rotation of the crankshaft 22 is caused to be burned by the ignition plug 29, thereby reciprocating the piston 25. Then, when the number of revolution of the crankshaft 22 exceeds a predetermined value (3000 rpm, for example) corresponding to the operating amount of the throttle grip, the rotational power of the crankshaft 22 is transmitted to the stepless speed changer 23, the one-way clutch 44, and the speed reduction mechanism 69 via the start-up clutch 40, thereby driving the rear wheel WR. [0042] When starting up, it is also possible to activate the drive motor 21b by power distribution from the buttery 74, and assist the rotation of the driven shaft 60 by the engine power. Instead of the start-up by the engine 20, the startup only by the drive motor 21b is also possible. In this case, since rotation of the driven shaft 60 by the drive motor 21b is not transmitted to the driven side power transmission pulley 62 by the one-way clutch 44, the stepless speed changer 23 is not driven. Accordingly, when the rear wheel WR is driven only by the drive motor 21b for traveling, the energy transmission efficiency is improved. [0043] When traveling only by the engine 20 and when a load during acceleration or during travel at a high speed is significant, the drive motor 21b may be used to assist the traveling by the engine. At this time, the rotational power of the crankshaft 22 caused by the reciprocal motion of the piston 25 is transmitted to the driven shaft 60 via the start-up clutch 40, the stepless speed changer 23, and the one-way clutch 44, and the power from the drive motor 21b is also transmitted thereto via the one-way clutch 44, whereby the rear wheel WR is driven by the combined power via the speed reduction mechanism 69. In contrast, when traveling only by the drive motor 21b, the engine 20 may be used to assist the traveling by the motor. [0044] In the traveling at a constant speed (cruise traveling), in the case where only the drive motor 21b is used as a power source, even when the engine 20 is driven, power can be generated by the ACG starter motor 2la without driving the stepless speed changer 23 as long as the number of revolution of the engine 20 does not exceed the number of revolution when the start-up clutch 40 is connected (the above-described predetermined value). In the case where only the drive motor 21b is used as a power source during the traveling at the constant speed, power transmission from the drive motor 21b to the rear wheel WR is performed without driving the stepless speed changer 23, high energy transmission efficiency is achieved. [0045] When reducing the speed, since the one-way clutch 44 does not transmit the rotation of the driven shaft 60 to the driven side power transmission pulley 62 of the stepless speed changer 23, rotation of the axle 68 can be regenerated at the drive motor 21b directly via the speed reduction mechanism 69 without driving the stepless speed changer 23. In other word, since the power transmitted from the rear wheel WR to the drive motor 21b during regenerative operation from the rear wheel WR to the drive motor 21b is not consumed for driving the stepless speed changer 23, the charging efficiency at the time of regeneration is improved. [0046] Subsequently, the speed reduction mechanism 69 is described in detail. As shown in fig. 5, the gear case 70 is composed of a container-shaped case body 70A having an opening on the outside in terms of the vehicle width direction, and part of an inner wall portion (wall portion) 59C of the power transmission case 59 (case body 59A) to which the opening side of the case body 70A faces, and the case body 70A is fixed to the inner wall potion 59C of the power transmission case 59 in a state in which the opening thereof is closed by the inner wall portion 59C. [0047] The driven shaft 60, which is an input shaft of the speed reduction mechanism 69, is provided in such a manner that the right portion thereof is penetrated through the inner wall portion 59C of the power transmission case 59 and is projected into a space 70K within the gear case 70. The left end portion of the driven shaft 60 is rotatably supported by a radial ball bearing 85, which is a bearing disposed on the side of a space 59K of an outer wall portion 59D of the power transmission case 59 (cover 59B) . The right end portion of the driven shaft 60 is rotatably supported by a radial ball bearing 86, which is a bearing disposed on the side of a space 70K of a bottom wall portion (inner wall portion) 70C of the gear case 70. The right portion of the driven gear 60 is rotatably supported also by a radial ball bearing 87 (the second bearing) which is a bearing disposed on the side of the gear case 70 of the inner wall portion 59C of the power transmission case 59. Disposed at the right end portion of the driven shaft 60 between the both radial ball bearings 86, 87 which support the right portion and adjacent to the radial ball bearing 86 on the right end side, a small-diameter gear 71A is integrally formed on the outer periphery thereof. [0048] The intermediate shaft 73 of the speed reduction mechanism 69 is integrally fixed on the right portion thereof with a large-diameter gear 7 IB which meshes with the small-diameter gear 71A on the driven shaft 60, and the large-diameter gear 7 IB and the small-diameter gear 71A of the driven shaft 60 constitute the first speed reduction gear pair 71. A portion of the intermediate shaft 73 on the left side of the large-diameter gear 7IB, there is integrally formed a small-diameter gear 72A on the outer periphery thereof. The left end of the intermediate gear 73 is rotatably supported by a radial ball bearing 88 (the first bearing) which is a bearing disposed at the inner wall portion 59C of the power transmission case 59 on the side of the space 70K of the gear case 70, and the right end of the intermediate shaft 73 is rotatably supported by a radial ball bearing 89, which is a bearing disposed on the bottle wall portion 70C of the gear case 70 on the side of the space 70K. Given the portion of the intermediate shaft 73 between the small-diameter gear 72 A and the radial ball bearing 88 on the left end side is a general-diameter portion 73a of the intermediate shaft 73, the maximum outer diameter (outer diameter of addendum circle) of the small-diameter gear 72A is larger than the outer diameter thereof. [0049] The axle 68, which is an output shaft of the speed reduction mechanism 69, is penetrated through a hub portion 7OB provided on the bottom wall portion 70C of the gear case 70 and is spline connected to a hub portion 77 of a wheel 76 of the rear wheel WR. A brake drum 78 formed so as to surround the hub portion 77 is integrally provided on the inner peripheral side of the wheel 76, and a drum brake device of the rear wheel WR is configured of the brake drum 78 and a base portion 79 provided integrally on the right side of the gear case 70. The left end portion of the axle 68 is rotatably supported by a radial ball bearing 90, which is a bearing provided at the inner wall portion 59C of the power transmission case 59 on the side of the space 70K of the gear case 70, and the right portion of the axle 68 is rotatably supported by a radial ball bearing 91, which is a bearing disposed within the hub portion 70B of the gear case 70. Provided on the axle 68 between the both radial ball bearing 90, 91 which supports the left end portion and the right portion of the axle 68 and adjacent to the radial ball bearings 90 on the left end side, a large-diameter gear 72B which meshes with the small-diameter gear 72A of the intermediate shaft 73 is integrally fixed therewith, and the large-diameter gear 72B and the smalldiameter gear 72A of the intermediate shaft 73 constitute the second speed reduction gear pair 72. [0050] The radial ball bearing 85 on the left end side of the driven shaft 60 is disposed within a storage section 92 which is formed by shifting part of the outer wall portion 59D of the power transmission case 59 leftward. The storage section 92 has an inner peripheral surface which aligns with the outer peripheral surface of the outer lace of the radial ball bearing 85. Therefore, by press-fitting the radial ball bearing 85 from the space 7OK of the gear case 70 leftward into the storage section 92, the radial ball bearing 85 is supported by the outer wall portion 59D over the entire perimeter thereof. Likewise, by mounting the radial ball bearing 86 on the right end side of the driven gear 60 from the side of the space 70K of the gear case 70 rightward into a storage section 93 provided on the bottom wall portion 70C of the gear case 70, the radial ball bearing 86 is supported over the entire perimeter thereof. [0051] By mounting the radial ball bearing 88 on the left end side of the intermediate shaft 73 from the side of the space 70K of the gear case 70 leftward into a storage section (recessed portion) 95 which is formed by shifting part of the inner wall portion 59C of the power transmission case leftward, the radial ball bearing 88 is supported by the inner wall portion 59C over the entire perimeter thereof, and by mounting the radial ball bearing 89 on the right end side of the intermediate shaft 73 from the side of the space 7OK of the gear case 70 rightward into a storage section 96 provided on the bottom wall portion 70C of the gear case 70, the radial ball bearing 89 is supported by the bottom wall portion 70C over the entire periphery thereof. By mounting the radial ball bearing 90 on the left end side of the axle 68 from the side of the space 70K of the gear case 70 leftward into a storage section 97 provided on the inner wall portion 59C of the power transmission case 59, the radial ball bearing 90 is supported by the inner wall portion 59C over the entire perimeter thereof, and by mounting the radial ball bearing 91 on the right portion of the axle 68 rightward from the side of the space 70K of the gear case 70 rightward into the hub portion 70B of the gear case 70, the radial ball bearing 91 is supported by the hub portion 70B over the entire perimeter thereof. [0052] The radial ball bearing 87 for supporting the right portion of the driven shaft 60 is attached to the power transmission case 59 via a separate bearing holder 100. Referring also Fig. 6, the bearing holder 100 includes an annular holder body 101 which surrounds the radial ball bearing 87, and three fixing flanges 102 extending from the right end portion of the holder body 101 toward the outer periphery thereof formed integrally with each other. The respective fixing flanges 102 are disposed at substantially regular intervals in the circumferential direction of the holder body 101, and the bearing holder 100 is fixed to the inner wall portion 59C when bolts 103 which penetrate through the respective fixing flanges 102 are tightened into the inner wall portion 59C. [0053] Two of the fixing flanges 102 are provided on the holder body 101 on the side of the intermediate shaft 73 so as to be substantially symmetry with respect to a straight line L connecting the shaft center of the driven shaft 60 and the shaft center of the intermediate shaft 73 in side view in Fig. 6, and the remaining one of the flanges is provided on the holder body 101 at the position opposite from the intermediate shaft 73. This is for preventing the fixing bolts 103 from being disposed between the driven shaft 60 and the intermediate shaft 73. [0054] The holder body 101 includes an inner peripheral surface which aligns with the outer peripheral surface of the outer lace of the radial ball bearing 87. By mounting the radial ball bearing 87 into the bolder body 101 by press-fitting or the like, the radial ball bearing 87 is retained in a state of being surrounded by the bearing holder 100 over the entire perimeter thereof. By mounting and fixing the bearing holder 100 from the side of the space 70K of the gear case 70 leftward into a mounting portion 94 of the inner wall portion 59C of the power transmission case 59, the radial ball bearing 87 is supported by the inner wall portion 59C via the bearing holder 100 over the entire perimeter thereof. [0055] The bearing holder 100 and the radial ball bearing 87 retained thereby are disposed so that the portion on the side of the intermediate shaft 73 is partly overlapped with the portion of the radial ball bearing 88 on the left end side of the intermediate shaft 73 on the side of the driven shaft 60 when viewed in the axial direction (lateral direction). The radial ball bearing 89 on the right end side of the intermediate shaft 73 is a component identical to the radial ball bearing 88 on the right end side, and these ball bearings are disposed coaxially. Therefore, the bearing holder 100 and the radial ball bearing 87 are overlapped also with the radial ball bearing 89 in axial view. [0056] In addition, since the radial ball bearing 88 on the left end side of the intermediate shaft 73 is stored in the storage section 95 which is formed by shifting part of the inner wall portion 59C of the power transmission case 59 leftward, the bearing holder 100 and the radial ball bearing 87 are located between the radial ball bearing 88 on the left end side of the intermediate shaft 73 and the small-diameter gear 72A in the axial direction, and the bearing holder 100 and the general-diameter portion 73a of the intermediate shaft 73 are disposed close to each other so that the portion of the bearing holder 100 on the side of the intermediate shaft 73 is partly overlapped with the maximum outer diameter portion of the small-diameter gear 72A on the side of the driven shaft in axial view. Consequently, the distance between the driven shaft 60 and the intermediate shaft 73 are reduced, and the diameters of the respective gears 71A and 72B which constitute the first speed reduction gear pair 71 for linking the driven gear 60 and the intermediate shaft 73 are reduced. [0057] Since the storage section 95 in which the radial ball bearing 88 on the left end side of the intermediate shaft are disposed is formed into a recessed shape on the inner wall portion 59C of the power transmission case 59 when viewed from the side of the space 70K of the gear case 70, by disposing the radial ball bearing 88 in this storage section 95, the space for disposing components in the space 70K of the gear case 70 can be increased. Although the storage section 95 is formed into a projected shape on the inner wall portion 59C of the power transmission case 59 when viewed form the space 59K of the power transmission case 59, since the storage section 95 is provided so as to be positioned on the inner side of the bowl-shaped driven side fixed pulley half 62a, the influence to the space for disposing the components in the space 59K is constrained, whereby lowering of flexibility of layout of the stepless speed changer 23 is prevented. [0058] By disposing the radial ball bearing 88 axially between the set of the bearing holder 100 and the radial ball bearing 87 and the inner wall portion 59C (the bottom wall portion of the storage section 95), the bearing holder 100 and the radial ball bearing 87 serve also as a stopper for preventing the bearing holder 100 and the radial ball bearing 87 from coming off from the storage section 95 of the radial ball bearing 88. Since a space S is formed between the radial ball bearing 88 and the set of the bearing holder 100 and the radial ball bearing 87 in the axial direction, the part tolerance of the respective radial ball bearings 87, 88 and the bearing holder 100 in the axial direction, and the mounting tolerance with respect to the inner wall portion 59C can be absorbed. The radial ball bearing 88 which is disposed within the storage section 95 formed by shifting part of the inner wall portion 59C leftward is disposed on the far side (that is, the left side) of the radial ball bearing 87 in terms of the mounting direction of the respective radial ball bearings 87, 88. In other words, the radial ball bearing 87 is disposed on the front side (that is, the right side) of the radial ball bearing 88 in the mounting direction. [0059] Since the first embodiment employs an arrangement structure of bearings in which the driven shaft 60 and the intermediate shaft 73, which are disposed in substantially parallel to each other and linked to each other are rotatably supported via the radial ball bearings 87, 88, respectively, and the respective radial ball bearings 87 88 are disposed so as to be overlapped partly with each other in axial view, the center distance between the driven shaft 60 and the intermediate shaft 73 is reduced and diameters of the small-diameter gear 71A and the large-diameter gear 7IB which link the shafts 60, 73 are reduced respectively in comparison with the case in which the respective radial ball bearings 87, 88 are disposed in a juxtaposed manner so as to extend along the inner wall portion 59C of the power transmission case 59 which supports the respective radial ball bearings 87, 88. Therefore, downsizing of the rear portion of the power unit 11 including the gear case 70 is achieved, and weight reduction by reducing the diameters of the respective gears 71A, 7IB is also achieved. In particular, in the motorcycle 1A of a unit swing type, the weight reduction of the rear portion, which corresponds to the distal side of swinging motion of the power unit 11 which is located below the spring, is very effective in terms of the traveling performance of the motorcycle 1A. [0060] In the arrangement structure of bearings described above, since the respective radial ball bearings 87, 88 are mounted from the side of the space 70K of the gear case 70 leftward into the inner wall portion 59C which supports the radial ball bearings 87, 88, when assembling the speed reduction mechanism 69 which includes the radial ball bearings 87, 88, the radial ball bearings 87, 88 can be mounted to the inner wall portion 59C in the same direction. In other words, the mounting properties of the respective radial ball bearings 87, 88 can be improved. Since maintenance of the radial ball bearings 87, 88 can be performed in the same direction by removing the gear case 70, maintenanceability of the respective radial ball bearings 87, 88 can be improved. [0061] In the arrangement structure of bearings described above, since the storage section 95 is formed on the inner wall portion 59C for supporting the respective radial ball bearings 87, 88 so that the radial ball bearing 88 is arranged on the far side with respect to the radial ball bearing 87 in terms of the mounting direction of the radial ball bearings 87, 88, when mounting the respective radial ball bearings 87, 88 on the inner wall portion 59C,the radial ball bearing 88 is mounted to the inner wall portion 59C in a state in which the radial ball bearing 88 is disposed within the storage section 95 so as to dispose the same in the far side in terms of the mounting direction, and then, the radial ball bearing 87 is mounted to the inner wall portion 59C. Accordingly, the respective radial ball bearings 87, 88 can be easily mounted, whereby assembleability of these ball bearings can be further improved. [0062] Since the radial ball bearing 88 is disposed within the recessed storage section 95, even when the positions to arrange the radial ball bearings 87, 88 are shifted in the axial direction so as to overlap with each other in axial view, the space 70K in the gear case 70 is not reduced. In contrast, since the radial ball bearing 88 is stored in the storage section 95, the space for arranging the parts in the space 70K can be increased. In this manner, efficient arrangement of the radial ball bearing 88 is enabled, whereby further downsizing of the power unit 11 including the gear case 70 is achieved. [0063] Furthermore, in the arrangement structure of bearings described above, since the bearing holder 100 for surrounding and retaining the radial ball bearing 88 is provided, and the radial ball bearing 88 is mounted to the inner wall portion 59C via the bearing holder 100, the radial ball bearing 88 can be supported via the bearing holder 100 over the entire perimeter thereof. In other words, the mounting strength of the radial ball bearing 88 with respect to the inner wall portion 59C can be improved. [0064] Furthermore, in the arrangement structure of bearings described above, since the radial ball bearing 88 is disposed between the set of the bearing holder 100 and the radial ball bearing 87 and the inner wall portion 59C in the axial direction, and the set of the radial ball bearing 88 and the bearing holder 100 and the radial ball bearing 87 are disposed so as to form the space S in the axial direction, the part tolerance of the respective radial ball bearings 87, 88 and the bearing holder 100 in the axial direction and the mounting tolerance with respect to the inner wall portion 59C can be absorbed, and hence mounting accuracy of the respective radial ball bearings 87, 88 and the bearing holder 100 can be improved. [Second Embodiment] [0065] Subsequently, a second embodiment of the present invention will be described. In this second embodiment, since only the fact that the bearing holder 100 is not used is different from the first embodiment, the parts corresponding to the first embodiment are represented by the same reference numerals and the description will be omitted. [0066] As shown in Figs. 7 and 8, in the arrangement structure of bearings according to the second embodiment, by mounting the radial ball bearing 87 for supporting the right portion of the driven shaft 60 to the mounting portion 94 provided on the inner wall portion 59C of the power transmission case 59 leftward from the side of the space 70K of the gear case 70 by press-fitting or the like, the radial ball bearing 87 is supported by the inner wall portion 59C. The portion of the radial ball bearing 87 on the side of the intermediate shaft 73 is disposed so as to overlap partly with the radial ball bearing 88 on the left end side of the intermediate shaft 73 in axial view. [0067] In the same manner as the first embodiment, the radial ball bearing 88 is disposed between the radial ball bearing 87 and the inner wall portion 59C (the bottom wall portion of the storage section 95) in the axial direction. In addition, a space S' is formed between the respective radial ball bearings 87, 88. Furthermore, the radial ball bearing 88 disposed within the storage section 95 is disposed on the far side with respect to the radial ball bearing 87 in the mounting direction of the radial ball bearings 87, 88. [0068] In the arrangement structure of bearings according to the second embodiment as well, as in the first embodiment, the assembleability of the radial ball bearings 87, 88 is improved and maintenanceability of the speed reduction mechanism 69 is improved in addition to the achievement of weight reduction by downsizing of the rear portion of the power unit 11 including the gear case 70 and reduction of the diameters of the respective gears 71A, 7IB. Also, mounting accuracy of the radial ball bearings 87, 88 can be improved by absorbing the part tolerance of the radial ball bearings 87, 88 in the axial direction and the mounting tolerance thereof with respect to the inner wall portion 59C. [0069] The invention is not limited to the embodiments described above and, for example, the mounting strength of the radial ball bearing 88 with respect to the inner wall portion 59C can be improved by eliminating the space S or S' between the radial ball bearings 87, 88 and interposing the radial ball bearing 88 between the radial ball bearing 87 and the inner wall portion 59C (the bottom wall portion of the storage section 95) in the axial direction, the mounting strength of the radial ball bearing 88 with respect to the inner wall portion 59C can be improved. In addition, as long as a structure is such that the respective bearings are partly overlapped in axial view between the radial ball bearing 88 which supports the intermediate shaft 73 and the radial ball bearing 90 which supports the axle 68, or between the radial ball bearings 86, 89 which are mounted to the bottom wall portion 70C of the gear case 70, the arrangement structure of bearings as described above can be applied. Furthermore, when using the bearing holder 100, for example, fixation by press-fitting or the like may be employed besides the fixation to the gear case 70 using a bolt. Alternatively, a structure in which the storage section 95 is a recess formed in the vicinity thereof for simply shifting the radial ball bearing 88 leftward, and the radial ball bearing 88 is supported by other supporting means. The structures in the respective embodiments are shown simply for illustration, and various modifications may be made without departing from the scope of the invention, as a mater of course. [Reference Numerals] [0071] 59C inner wall portion (wall portion) 60 driven shaft (power transmission shaft) 73 intermediate shaft (power transmission shaft) 87 radial ball bearing (second bearing) 88 radial ball bearing (first bearing) 95 storage section (recessed portion) 100 bearing holder (bearing holder) We claim: 1. An arrangement structure for bearings comprising: a plurality of power transmission shafts (60) positioned in a substantially parallel arrangement relative to each other, the power transmission shafts (60) being rotatably supported via bearings, respectively, and arranged so that the bearings overlap partly with each other in an axial view; whereby a center-to-center distance between the power transmission shafts (60) can be minimized; a wall portion (59C) having a surface facing a space in which the power transmission shafts (60) are disposed and being formed with a recess that is axially displaced from an adjacent region of the wall portion (59C), the bearings being mounted to the surface of the wall portion (59C) substantially in the same direction; a second bearing (87) contacts the wall portion (59C) in the axial direction at the adjacent region; and a first bearing (88) contacts the recess in the axial direction, whereby the first bearing (88) is disposed on the far side of the second in terms of the mounting direction of the bearings. 2. The arrangement structure for bearings as claimed in claim 1, wherein a bearing holder (100) is provided for surrounding and retaining the second bearing (87), and the second bearing (87) is mounted to the wall portion (59C) via the bearing holder (100). 3. The arrangement structure for bearings as claimed in claim 2, wherein the first bearing (88) is disposed between the second bearing (87) and the wall portion (59C) in the axial direction. 4. The arrangement structure for bearings as claimed in claim 2, wherein a space is formed between the first bearing (88) and the second bearing (87) in the axial direction. 5. The arrangement structure for bearings as claimed in claim 1, wherein the first bearing (88) is disposed between the second bearing (87) and the wall portion (59C) in the axial direction. 6. The arrangement structure for bearings as claimed in claim 5, wherein a space is formed between the first bearing (88) and the second bearing (87) in the axial direction. 7. The arrangement structure for bearings as claimed in claim 1, wherein a space is formed between the first bearing (88) and the second bearing (87) in the axial direction. 8. An arrangement structure for bearings comprising: a plurality of power transmission shafts (60) positioned to be rotatably supported via bearings, respectively, and arranged so that the bearings overlap partly with each other in an axial view, whereby a center-to-center distance between the power transmission shafts (60) can be minimized; a wall portion (59C) for supporting a first bearing (88) for rotatably supporting a first power transmission shaft; said wall portion (59C) supports a second bearing (87) for rotatably supporting a second power transmission shaft; said wall portion (59C) having a surface facing a space in which the power transmission shafts (60) are disposed and being formed with a recess that is axially displaced from an adjacent region of the wall portion (59C) , said first and second bearing (87) s being mounted to the surface of the wall portion (59C) substantially in the same direction; the second bearing (87) contacts the wall portion (59C) in the axial direction at the adjacent region: and the first bearing (88) contacts the recess in the axial direction, whereby the first bearing (88) is disposed on the far side of the second bearing (87) in terms of the mounting direction of the bearings. 9. The arrangement structure for bearings as claimed in claim 8, wherein a bearing holder (100) is provided for surrounding and retaining the second bearing (87) and the second bearing (87) is mounted to the first wall portion (59C) via the bearing holder (100). 10. The arrangement structure for bearings as claimed in claim 9, wherein the first bearing (88) is disposed between the second bearing (87) and the wall portion (59C) in the axial direction. 11. The arrangement structure for bearings as claimed in claim 9, wherein a space is formed between eh first bearing (88) and the second bearing (87) in the axial direction. 12. The arrangement structure for bearings as claimed in claim 8, wherein the first bearing (88) is disposed between the second bearing (87) and the wall portion (59C) in the axial direction. 13. The arrangement structure for bearings as claimed in claim 12, wherein a space is formed between the first bearing (88) and the second bearing (87) in the axial direction. 14. The arrangement structure for bearing as claimed in claim 8, wherein a space is formed between eh first bearing (88) and the second bearing (87) in the axial direction.

Full Text

The present invention relates to an arrangement of bearings for a plurality of torque transmission elements. [Background Art]
Hitherto, there is proposed, for example, in Patent Document 1, an arrangement structure for bearings in which a plurality of power transmission shafts linked to each other are arranged in substantially parallel to each other for rotatably supporting the respective power transmission shafts via the bearings respectively.
This technology has a structure in which the respective bearings are mounted to wall portions which, support the bearings from both sides, so that the respective bearings are partly overlapped when viewed in axial view. [Patent Document 1] Patent Publication No. 3039168 (Fig. 5) [Disclosure of the Invention] [Problems to be Solved by the Invention]
However, in the arrangement structure of bearings as described above, although the center distance between the power transmission shafts can be reduced, since the bearings which

3-Xare
overlapped with each other in axial view are mounted to
the wall portion from the opposite directions, assembly of a
unit including these bearings may take a lot of trouble. When
considering maintenance of bearings or the like by
disassembling the unit, since the structure of the wall
portions is complicated, maintenance may take a lot of trouble.
Accordingly the present invention provides an
arrangement structure of bearings for improving
assembleability and maintenanceability of the respective
bearings which overlap in the axial direction.
[Means for Solving the Problems]
[0004]
As a solving means of the above described subject, the
invention as set forth in Claim 1 is an arrangement structure
of bearings including a plurality of power transmission shafts
(for example, a driven shaft 60, an intermediate shaft 73 in
an embodiment) linked in substantially parallel to each other,
the power transmission shafts being rotatably supported via
bearings (for example, radial ball bearings 87, 88 in the
embodiment) respectively and arranged so that the bearings are
overlapped partly with each other in axial view, characterized
in that a wall portion for supporting the respective bearings
(for example, an inner wall portion 59C in the embodiment) is
provided, and the respective bearings are mounted to the wall
portion substantially in the same direction.
[0005]
In this structure, when assembling the unit including
the respective bearings, the respective bearings may be mounted
to the wall portion substantially in the same direction.
Likewise, maintenance of the respective bearings can be
performed substantially in the same direction.
[0006]
The invention as set forth in Claim 2 is characterized
in that the wall portion is formed with a recess (for example,
a storage section 95 in the embodiment) so that a first bearing
(for example, the radial ball bearing 88 in the embodiment)
of the bearings is disposed on the far side of a second bearing
(for example, the radial ball bearing 87 in the embodiment)
of the bearings in terms of the mounting direction of the
respective bearings, the bearings being overlapped to each
other in axial view.
[0007]
In this arrangement, when mounting the respective
bearings to the wall portion, the first bearing is mounted to
the wall portion in a state of being disposed within the recess
to place on the far side in terms of mounting direction, and
then the second bearing is mounted to the wall portion.
[0008]
The invention as set forth in Claim 3 is characterized
in that a bearing holder (for example, a bearing holder 100
in the embodiment) for surrounding and retaining the second
bearing, and the second bearing is mounted to the wall portion
via the bearing holder.
[0009]
In this arrangement, the second bearing can be supported
via the bearing holder over the entire perimeter.
[0010]
The invention as set forth in Claim 4 is characterized
in that the first bearing is disposed between the second bearing
and the wall portion in the axial direction.
[0011]
In this arrangement, the first bearing can be interposed
between the second bearing and the wall portion.
[0012]
The invention as set forth in Claim 5 is characterized
in that a space is formed the second bearing and the first
bearing in the axial direction.
[0013]
In this arrangement, the part tolerance of the respective
bearings in the axial direction and the mounting tolerance with
respect to the wall portion can be absorbed.
[Advantage of the Invention]
[0014]
According to the invention as set forth in Claim 1,
assembleability and maintenanceability of the respective
bearings can be improved.
According to the invention as set forth in Claim 2, mounting of the respective bearings are facilitated, and assembleability thereof can further be improved.
According to the invention as set forth in Claim 3, the mounting force of the second bearing with respect to the wall portion can be improved.
According to the invention as set forth in Claim 4, the mounting force of the first bearing with respect to the wall portion can be improved.
According to the invention as set forth in Claim 5, mounting accuracy of the respective bearings can be improved. [Best Mode for Carrying Out the Invention]
Referring now to the drawings, embodiments of the present invention will be described.

[Brief Description of the Drawings]
[Fig. 1] Fig. 1 is a side view of a motorcycle according to
an embodiment of the present invention.
[Fig. 2] Fig. 2 is a block diagram showing a system structure
of the motorcycle shown in Fig. 1.
[Fig. 3] Fig. 3 is a cross-sectional view explanatory drawing
of a power unit of the motorcycle shown in Fig. 1.
[Fig. 4] Fig. 4 is an enlarged view of the periphery of a
stepless speed changer in Fig. 3.
[Fig. 5] Fig. 5 is an enlarged view of the periphery of a speed
reduction mechanism in Fig. 3.
[Fig. 6] Fig. 6 is a view of the periphery of a driven shaft
and an intermediate shaft of the speed reduction mechanism when
viewed in the direction indicated by an arrow F in Fig. 5.
[Fig. 7] Fig. 7 is an enlarged view of a second embodiment
of the present invention corresponding to Fig. 5.
[Fig. 8] Fig. 8 is a view of the periphery of the driven shaft
and the intermediate shaft in Fig. 7 when viewed in the
direction of an arrow F'.

Terms representing the directions such as front, rear, left and right correspond to the directions with respect to a vehicle. [First Embodiment]
In Fig. 1, reference numeral lA designates a unit swing system motorcycle configured as a hybrid vehicle. The motorcycle 1A includes a front fork 1 which rotatably supports a front wheel WF at the front of the vehicle body. The front wheel WF and the front fork 1 are rotatably supported by a head

pipe 2, so as to be capable of steering by the operation of
a handle 3. A down pipe 4 is mounted to the head pipe 2 so
as to extend rearward and downward, and an intermediate frame
5 is extending substantially horizontally from the lower end
of the down pipe 4.
[0017]
A rear frame 6 is formed rearward and upward from the
rear end of the intermediate frame 5. The front end of a power
unit 11 including an engine 20 as a prime mover of the motorcycle
1A, described later, is rotatably attached to a vehicle body
frame 10 configured as described above. The power unit 11 is,
so-called, a unit swing system which swings in the vertical
direction about the front end thereof, which is rotatably
mounted to the vehicle body frame 10. A rear wheel WR, which
is a drive wheel, is rotatably mounted to the rear end of the
power unit 11. Mounted between the power unit 11 and the rear
frame 6 is a rear cushion, not shown.
[0018]
The periphery of the vehicle body frame 10 is covered
by a vehicle body cover 13, and a seat 14 on which a rider seats
is disposed at the rear on the upper surface of the vehicle
body cover 13. A step floor 15 on which the feet of the rider
are placed is formed forwardly of the seat 14. A storage box
12 is provided below the seat 14, which is opened and closed
by the seat 14 and is functioned as a utility space for storing,
for example, a helmet, baggage, or the like.
[0019]
As shown in Fig. 2, the power unit 11 includes an engine
20, which is an internal combustion engine for generating an
output by burning combustible air-fuel mixture, an ACG starter
motor 2la which functions as a starter and a power generator,
a stepless speed changer 23 connected to a crankshaft 22 of
the engine 20 for transmitting a rotational power of the engine
20 to the rear wheel WR, a start-up clutch 40 for connecting
and disconnecting power transmission between the crankshaft
22 and the input side of the stepless speed changer 23, a drive
motor 21b which functions as a dynamotor or a power generator,
a one-way clutch 44 which can transmit the rotational power
only from the engine 20 and the drive motor 21b to the side
of the rear wheel WR according to the input number of revolution,
and a speed reduction mechanism 69 for reducing the speed of
the rotational power from the stepless speed changer 23 and
transmitting it to the rear wheel WR.
[0020]
The rotational power from the engine 20 is transmitted
from the crankshaft 22 to the rear wheel WR via the startup
clutch 40, the stepless speed changer 23, the one-way clutch
44, a driven shaft (power transmission shaft) 60 disposed on
the output side of the stepless speed changer 23, and the speed
reduction mechanism 69.
On the other hand, the power from the drive motor 21b
is transmitted to the rear wheel WR via the driven shaft 60,
and the speed reduction mechanism 69. In other words, the
driven shaft 60 which serves as a drive shaft of the rear wheel
WR via the speed reduction mechanism 69 also corresponds to
the output shaft of the drive motor 21b.
[0021]
A battery 74 is connected to the ACG starter motor 2la
and the drive motor 2 Ib. The battery 74 supplies electric power
to the motors 2la, 21b when the drive motor 21b functions as
the dynamotor, and when the ACG starter motor 2la functions
as the starter. When the ACG starter motor 2la and the drive
motor 21b function as the power generators, regenerative
electric power therefrom is charged. Control of the engine
20, the ACG starter motor 2la, and the drive motor 21b is
performed a control unit 7 which is control means including
a CPU (Central Processing Unit), a ROM (Read Only Memory) and
a RAM (Random Access Memory) and so on.
[0022]
The engine 20 is configured to intake and burn air-fuel
mixture including air and fuel from an air-intake pipe 16, and
a throttle valve 17 for controlling the amount of air is
rotatably provided in the air-intake pipe 16. The throttle
valve 17 is rotated by the operating amount of a throttle grip,
not shown, which is operated by the rider. Provided between
the throttle valve 17 and the engine 20 are an injector 18 for
injecting fuel and a negative pressure sensor 19 for detecting
negative pressure in the air-intake pipe 16 (air-intake pipe
negative pressure).
[0023]
As shown in Fig. 3, a piston 25 is connected to the
crankshaft 22 of the engine 20 via a connecting rod 24, and
the piston 25 is fitted into a cylinder 27 provided in a cylinder
block 26. Then, by burning air-fuel mixture in a combustion
chamber 20a defined by a cylinder head 28, the cylinder 27 and
the piston 25, the piston 25 reciprocates in the cylinder 27
and the crankshaft 22 rotates to output the rotational power.
Reference numeral 29 designates an ignition plug for igniting
air-furl mixture.
[0024]
Opening and closing of a valve, not shown, for
controlling intake or exhaust of air-fuel mixture to/from the
combustion chamber 20a is performed by rotating a camshaft 30
supported by the cylinder head 28. A driven sprocket 31 is
provided on the right end of the camshaft 30, and an endless
cam chain 33 is wound around the driven sprocket 31 and the
drive sprocket 32 provided on the right end of the crankshaft
22 . A water pump 34 is provided on the camshaft 30 on the right
side of the driven sprocket 31, and the water pump 34 works
as the camshaft 30 rotates.
[0025]
A stator case 49 is connected to the right side of a
crankcase 48 which supports the crankshaft 22, and the ACG
starter motor 21a is stored within the stator case 49. The
ACG starter motor 2la is a motor of so-called an outer rotor
system, and the stator is a coil 51 formed by winding a conductor
wire wired on a teeth 50 fixed to the stator case 49. An outer
rotor 52 has substantially cylindrical shape covering the outer
periphery of the stator, and is provided with a magnet 53 on
the inner peripheral surface thereof. The outer rotor 52 is
coaxially fixed to the crankshaft 22. A fan 54a for cooling
the ACG starter motor 2la is mounted to the left side of the
outer rotor 52.
[0026]
A power transmission case 59 which extends toward the
rear wheel WR is connected to the left side of the crankcase
48. The power transmission case 59 can be divided into a case
body 59A which constitutes an inside (right side) portion
thereof in terms of the vehicle width direction and a cover
59B to be mounted from the outside (left side) of the case body
59A in terms of the vehicle width direction. In a space 59K
defined therein, a fan 54b fixed to the left end of the
crankshaft 22, the start-up clutch 40, the stepless speed
changer 23 connected at the input side thereof to the crankshaft
22 via the start-up clutch 40, and the drive motor 21b connected
to the output side of the stepless speed changer 23 are stored.
[0027]
A cooling air intake port 59a is formed on the front left
side of the power transmission case 59 in the vicinity of the
fan 54b. When the fan 54b is rotated synchronously with the
crankshaft 22, outside air is taken from the cooling air intake
port 59a into the power transmission case 59, so that the drive
motor 21b and the stepless speed changer 23 are cooled
compulsorily.
[0028]
The stepless speed changer 23 is configured as, so-called,
a belt converter including a drive side power transmission
pulley 58, which is the input side to be mounted to the left
end of the crankshaft 22 projected leftward from the crankcase
48 in terms of the vehicle width direction via the start-up
clutch 40, a driven side power transmission pulley 62, which
is the output side to be mounted to a driven shaft 60 supported
by the power transmission case 59 along the axis in parallel
with the crankshaft 22 via the one-way clutch 44, and an endless
V-belt (endless belt) 63 wound on these pulleys 58, 62 so as
to interconnect there between. The driven shaft 60 is provided
so as to penetrate through the drive motor 21b and the driven
side power transmission pulley 62, and the driven shaft 60 is
rotatably supported by a gear case 70, in which the power
transmission case 59 and the speed reduction mechanism 69 are
stored.
[0029]
Referring also to Fig. 4, the drive side power
transmission pulley 58 is mounted to the crankshaft 22 via a
sleeve 58d through which the crankshaft 22 is penetrated so
as to be capable of rotating in the circumferential direction,
and includes a drive side fixed pulley half 58a secured on the
sleeve 58d, and a drive side movable pulley half 58c, which
is disposed on the outside (right side) of the drive side fixed
pulley half 58a in terms of the vehicle width direction, and
is mounted so as to be capable of sliding axial with respect
to the sleeve 58d but not to be capable of rotating in the
circumferential direction. The drive side fixed pulley half
58a and the drive side movable pulley half 58c are substantially
bowl shape. The drive side fixed pulley half 58a is disposed
so that the outer peripheral side thereof is positioned inside
(left side) of the inner peripheral side in the vehicle width
direction, and the drive side movable pulley half 58c is
disposed so that the outer peripheral side thereof is
positioned on the outside (left side) of the inner peripheral
side in terms of the vehicle width direction.
[0030]
On the other hand, the driven side power transmission
pulley 62 is mounted to the driven shaft 60 passing there through
so as to be capable of rotating in the circumferential direction,
and includes a driven side fixed pulley half 62a which is
restrained in sliding movement with respect to the driven shaft
60 in the axial direction thereof, and a driven side movable
pulley half 62b mounted on a boss 62c through which the driven
shaft 60 of the driven side fixed pulley half 62a is passed
so as to be capable of sliding movement in the axial direction
thereof. The driven side fixed pulley half 62a and the driven
side movable pulley half 62b are also substantially bowl shape.
The driven side fixed pulley half 62a is disposed so that the
outer peripheral side thereof is positioned inside (left side)
of the inner peripheral side in terms of the vehicle width
direction, and the driven side movable pulley half 62b is
disposed so that the outer peripheral side is positioned
outside (left side) of the inner peripheral side in terms of
the vehicle width direction.
[0031]
The endless V-belt 63 is wound around belt grooves of
V-shape in cross section, which are formed between the drive
side fixed pulley half 58a and the drive side movable pulley
half 58c, and between the driven side fixed pulley half 62a
and the driven side movable pulley half 62b, respectively.
[0032]
A weight roller 58b is disposed inside the bowl shape
of the drive side movable pulley half, that is, on the right
side. Centrifugal force generated by the rotation of the drive
side power transmission pulley 58 is exerted to the weight
roller 58b, and then moves the weight roller 58b to the outer
peripheral side of the drive side power transmission pulley
58, so that the drive side movable pulley half 58c slides toward
the drive side fixed pulley half 58a.
On the other hand, a spring 64 is provided on the left
side of the driven side movable pulley half 62b/ and the driven
side movable pulley half 62b is constantly urged toward the
driven side fixed pulley half 62a by a resilient force of the
spring 64.
[0033]
In this arrangement, when the number of revolution of
the crankshaft 22 increases, the centrifugal force exerted on
the weight roller 58b in creases on the drive side power
transmission pulley 58, and hence the drive side movable pulley
half 58c slides toward the drive side fixed pulley half 58a.
The drive side movable pulley half 58c moves closer to the drive
side fixed pulley half 58a by the amount of this sliding
movement, and the width of the groove of the drive side power
transmission pulley 58 is decreased. Consequently, the
contact position between the drive side power transmission
pulley 58 and the V-belt 63 is shifted radially outwardly of
the drive side power transmission pulley 58, whereby the
winding diameter of the V-belt 63 is increased. Accordingly,
the width of the groove on the driven side power transmission
pulley 62 formed by the driven side fixed pulley half 62a and
the driven side movable pulley half 62b is increased. In other
words, the winding diameter (diameter of transmission pitch)
of the V-belt 63 is continuously changed according to the number
of revolution of the crankshaft 22, and the gear-change ratio
is changed automatically and steplessly.
[0034]
The start-up clutch 40 includes a cup-shaped outer case
40a secured to the sleeve 58d, an outer plate 40b secured to
the left end of the crankshaft 22, a shoe 40d attached to the
outer edge of the outer plate 4Ob via a weight 40c so as to
face radially outwardly, and a spring 40e for urging the shoe
40d radially inwardly.
The start-up clutch 40 is disposed outside (left side
in this embodiment) of the stepless speed changer 23 in terms
of vehicle width direction, between the drive side fixed pulley
half 58a and the fan 54b, and in the vicinity of the cooling
air intake port 59a formed on the power transmission case 59.
[0035]
In this arrangement/ when the number of revolution of
the engine 20, that is, the number of revolution of the
crankshaft 22 is egual to or smaller than a predetermined value
(3000 rpm for example, which exceeds the number of revolution
for idling) , the start-up clutch 40 blocks power transmission
between the crankshaft 22 and the stepless speed changer 23,
while when the number of revolution of the engine 20 exceeds
the predetermined value, the centrifugal force exerted to the
weight 40c works against an urging force of the spring 40e which
works radially inwardly and hence the weight 40c moves radially
outwardly, whereby the shoe 40d presses the inner peripheral
surface of the outer case 40a by a force larger than the
predetermined value and the crankshaft 22 is connected to the
sleeve 58d via the start-up clutch 40. Accordingly, the
rotational power of the crankshaft 22 is transmitted to the
sleeve 58d via the start-up clutch 40, whereby the drive side
power transmission pulley 58 fixed to the sleeve 58d is driven.
[0036]
The one-way clutch 44 includes a cup-shaped outer clutch
44a, an inner clutch 44b inserted into the outer clutch 44a
coaxially, and a roller 44c which enables transmission of a
power only in one direction from the inner clutch 44b to the
outer clutch 44a. The outer clutch 44a serves also as the inner
rotor body of the drive motor 21b, and is configured of the
same material as the inner rotor body. Then, the inner
periphery of the boss of the inner rotor body and the outer
periphery of the driven shaft 60 which serves as the drive shaft
of the rear wheel WR are spline fitted via the speed reduction
mechanism 69, and the inner periphery of the inner clutch 44b
and the left end of the boss 62c of the driven side fixed pulley
half 62a are spline fitted.
[0037]
In this arrangement, a power from the engine 20
transmitted to the driven side power transmission pulley 62
of the stepless speed changer 23 is transmitted to the rear
wheel WR via the driven side fixed pulley half 62a, the inner
clutch 44b, the outer clutch 44a, that is, the inner rotor body,
the driven shaft 60, and the speed reduction mechanism 69, while
a power from the rear wheel WR side generated when the rider
pushes the vehicle manually or during regenerative operation
is transmitted to the speed reduction mechanism 69, the driven
shaft 60, the inner rotor body, that is, the outer clutch 44a.
However, since the outer clutch 44a runs idle with respect to
the inner clutch 44b, such power is not transmitted to the
stepless speed changer 23 and the engine 20.
[0038]
The drive motor 21b is provided in such a manner that
the driven shaft 60 disposed in parallel with the vehicle width
direction serves as a motor output shaft on the rear side of
the power transmission case 59. In other words, in the drive
motor 21b, the driven shaft 60, which is an input shaft to the
speed reduction mechanism 69, serves also as a motor output
shaft. It is for reducing the speed of the power from the drive
motor 21b by the speed reduction mechanism 69 provided
generally between the stepless speed changer 23 and the rear
wheel WR and transmitting the same to the rear wheel WR.
Accordingly, in comparison with the power unit which is not
provided with the speed reduction mechanism 69 between the
stepless speed changer 23 and the rear wheel WR and is directly
connected to the motor, increase in number of components due
to provide the speed reduction mechanism additionally can be
prevented, or the drive motor 21b can be downsized.
[0039]
An inner rotor 80 includes an inner rotor body which is
formed into cup shape and is spline fitted to the driven shaft
60 at a boss 80b formed at the center thereof, that is, the
inner clutch 44b, and a magnet 80c disposed on the outer
peripheral surface of the opening side of the inner clutch 44b.
On the other hand, a stator 83 is configured by a coil 83c formed
by winding a conductor wire on a teeth 83b fixed to a stator
case 83a in the power transmission case 59.
In this arrangement, the drive motor 21b functions as
a dynamotor when assisting the output of the engine 20, and
in addition, serves also as a power generator (generator) which
converts the rotation of the driven shaft 60 into the electric
energy and performs regenerative charging to the battery 74.
[0040]
The speed reduction mechanism 69 is provided in a gear
case 70 which continues from the power transmission case 59
on the right side of the rear end thereof. The speed reduction
mechanism 69 is provided with an intermediate shaft (power
transmission shaft) 73 which is supported in parallel with the
driven shaft 60 and an axle 68 of the rear wheel WR. The driven
shaft 60 and the intermediate shaft 73 are connected by a first
speed reduction gear pair 71, and the intermediate shaft 73
and the axle 68 are connected by a second speed reduction gear
pair 72.
In this arrangement, the rotational power of the driven
shaft 60 is transmitted to the axle 68 after having reduced
in speed at a predetermined speed reduction ratio via the first
speed reduction gear pair 71 and the second speed reduction
gear pair 72, whereby the rear wheel WR is driven so as to cause
the motorcycle 1A to be started and traveled.
[0041]
In the hybrid vehicle with the arrangement as described
above, when starting the engine, the crankshaft 22 is rotated
by the use of the ACG starter motor 2la on the crankshaft 22.
At this time, the start-up clutch 40 is not connected, and power
transmission from the crankshaft 22 to the stepless speed
changer 23 is blocked. Then, air-fuel mixture taken into the
cylinder 27 synchronously with the rotation of the crankshaft
22 is caused to be burned by the ignition plug 29, thereby
reciprocating the piston 25.
Then, when the number of revolution of the crankshaft
22 exceeds a predetermined value (3000 rpm, for example)
corresponding to the operating amount of the throttle grip,
the rotational power of the crankshaft 22 is transmitted to
the stepless speed changer 23, the one-way clutch 44, and the
speed reduction mechanism 69 via the start-up clutch 40,
thereby driving the rear wheel WR.
[0042]
When starting up, it is also possible to activate the
drive motor 21b by power distribution from the buttery 74, and
assist the rotation of the driven shaft 60 by the engine power.
Instead of the start-up by the engine 20, the startup
only by the drive motor 21b is also possible. In this case,
since rotation of the driven shaft 60 by the drive motor 21b
is not transmitted to the driven side power transmission pulley
62 by the one-way clutch 44, the stepless speed changer 23 is
not driven. Accordingly, when the rear wheel WR is driven only
by the drive motor 21b for traveling, the energy transmission
efficiency is improved.
[0043]
When traveling only by the engine 20 and when a load during
acceleration or during travel at a high speed is significant,
the drive motor 21b may be used to assist the traveling by the
engine. At this time, the rotational power of the crankshaft
22 caused by the reciprocal motion of the piston 25 is
transmitted to the driven shaft 60 via the start-up clutch 40,
the stepless speed changer 23, and the one-way clutch 44, and
the power from the drive motor 21b is also transmitted thereto
via the one-way clutch 44, whereby the rear wheel WR is driven
by the combined power via the speed reduction mechanism 69.
In contrast, when traveling only by the drive motor 21b,
the engine 20 may be used to assist the traveling by the motor.
[0044]
In the traveling at a constant speed (cruise traveling),
in the case where only the drive motor 21b is used as a power
source, even when the engine 20 is driven, power can be
generated by the ACG starter motor 2la without driving the
stepless speed changer 23 as long as the number of revolution
of the engine 20 does not exceed the number of revolution when
the start-up clutch 40 is connected (the above-described
predetermined value).
In the case where only the drive motor 21b is used as
a power source during the traveling at the constant speed, power
transmission from the drive motor 21b to the rear wheel WR is
performed without driving the stepless speed changer 23, high
energy transmission efficiency is achieved.
[0045]
When reducing the speed, since the one-way clutch 44 does
not transmit the rotation of the driven shaft 60 to the driven
side power transmission pulley 62 of the stepless speed changer
23, rotation of the axle 68 can be regenerated at the drive
motor 21b directly via the speed reduction mechanism 69 without
driving the stepless speed changer 23.
In other word, since the power transmitted from the rear
wheel WR to the drive motor 21b during regenerative operation
from the rear wheel WR to the drive motor 21b is not consumed
for driving the stepless speed changer 23, the charging
efficiency at the time of regeneration is improved.
[0046]
Subsequently, the speed reduction mechanism 69 is
described in detail.
As shown in fig. 5, the gear case 70 is composed of a
container-shaped case body 70A having an opening on the outside
in terms of the vehicle width direction, and part of an inner
wall portion (wall portion) 59C of the power transmission case
59 (case body 59A) to which the opening side of the case body
70A faces, and the case body 70A is fixed to the inner wall
potion 59C of the power transmission case 59 in a state in which
the opening thereof is closed by the inner wall portion 59C.
[0047]
The driven shaft 60, which is an input shaft of the speed
reduction mechanism 69, is provided in such a manner that the
right portion thereof is penetrated through the inner wall
portion 59C of the power transmission case 59 and is projected
into a space 70K within the gear case 70. The left end portion
of the driven shaft 60 is rotatably supported by a radial ball
bearing 85, which is a bearing disposed on the side of a space
59K of an outer wall portion 59D of the power transmission case
59 (cover 59B) . The right end portion of the driven shaft 60
is rotatably supported by a radial ball bearing 86, which is
a bearing disposed on the side of a space 70K of a bottom wall
portion (inner wall portion) 70C of the gear case 70. The right
portion of the driven gear 60 is rotatably supported also by
a radial ball bearing 87 (the second bearing) which is a bearing
disposed on the side of the gear case 70 of the inner wall portion
59C of the power transmission case 59. Disposed at the right
end portion of the driven shaft 60 between the both radial ball
bearings 86, 87 which support the right portion and adjacent
to the radial ball bearing 86 on the right end side, a
small-diameter gear 71A is integrally formed on the outer
periphery thereof.
[0048]
The intermediate shaft 73 of the speed reduction
mechanism 69 is integrally fixed on the right portion thereof
with a large-diameter gear 7 IB which meshes with the
small-diameter gear 71A on the driven shaft 60, and the
large-diameter gear 7 IB and the small-diameter gear 71A of the
driven shaft 60 constitute the first speed reduction gear pair
71. A portion of the intermediate shaft 73 on the left side
of the large-diameter gear 7IB, there is integrally formed a
small-diameter gear 72A on the outer periphery thereof. The
left end of the intermediate gear 73 is rotatably supported
by a radial ball bearing 88 (the first bearing) which is a
bearing disposed at the inner wall portion 59C of the power
transmission case 59 on the side of the space 70K of the gear
case 70, and the right end of the intermediate shaft 73 is
rotatably supported by a radial ball bearing 89, which is a
bearing disposed on the bottle wall portion 70C of the gear
case 70 on the side of the space 70K. Given the portion of
the intermediate shaft 73 between the small-diameter gear 72 A and the radial ball bearing 88 on the left end side is a
general-diameter portion 73a of the intermediate shaft 73, the
maximum outer diameter (outer diameter of addendum circle) of
the small-diameter gear 72A is larger than the outer diameter
thereof.
[0049]
The axle 68, which is an output shaft of the speed
reduction mechanism 69, is penetrated through a hub portion
7OB provided on the bottom wall portion 70C of the gear case
70 and is spline connected to a hub portion 77 of a wheel 76
of the rear wheel WR. A brake drum 78 formed so as to surround
the hub portion 77 is integrally provided on the inner
peripheral side of the wheel 76, and a drum brake device of
the rear wheel WR is configured of the brake drum 78 and a base
portion 79 provided integrally on the right side of the gear
case 70. The left end portion of the axle 68 is rotatably
supported by a radial ball bearing 90, which is a bearing
provided at the inner wall portion 59C of the power transmission
case 59 on the side of the space 70K of the gear case 70, and
the right portion of the axle 68 is rotatably supported by a
radial ball bearing 91, which is a bearing disposed within the
hub portion 70B of the gear case 70. Provided on the axle 68
between the both radial ball bearing 90, 91 which supports the
left end portion and the right portion of the axle 68 and
adjacent to the radial ball bearings 90 on the left end side,
a large-diameter gear 72B which meshes with the small-diameter
gear 72A of the intermediate shaft 73 is integrally fixed
therewith, and the large-diameter gear 72B and the smalldiameter
gear 72A of the intermediate shaft 73 constitute the
second speed reduction gear pair 72.
[0050]
The radial ball bearing 85 on the left end side of the
driven shaft 60 is disposed within a storage section 92 which
is formed by shifting part of the outer wall portion 59D of
the power transmission case 59 leftward. The storage section
92 has an inner peripheral surface which aligns with the outer
peripheral surface of the outer lace of the radial ball bearing
85. Therefore, by press-fitting the radial ball bearing 85
from the space 7OK of the gear case 70 leftward into the storage
section 92, the radial ball bearing 85 is supported by the outer
wall portion 59D over the entire perimeter thereof.
Likewise, by mounting the radial ball bearing 86 on the
right end side of the driven gear 60 from the side of the space
70K of the gear case 70 rightward into a storage section 93
provided on the bottom wall portion 70C of the gear case 70,
the radial ball bearing 86 is supported over the entire
perimeter thereof.
[0051]
By mounting the radial ball bearing 88 on the left end
side of the intermediate shaft 73 from the side of the space
70K of the gear case 70 leftward into a storage section
(recessed portion) 95 which is formed by shifting part of the
inner wall portion 59C of the power transmission case
leftward, the radial ball bearing 88 is supported by the inner
wall portion 59C over the entire perimeter thereof, and by
mounting the radial ball bearing 89 on the right end side of
the intermediate shaft 73 from the side of the space 7OK of
the gear case 70 rightward into a storage section 96 provided
on the bottom wall portion 70C of the gear case 70, the radial
ball bearing 89 is supported by the bottom wall portion 70C
over the entire periphery thereof.
By mounting the radial ball bearing 90 on the left end
side of the axle 68 from the side of the space 70K of the gear
case 70 leftward into a storage section 97 provided on the inner
wall portion 59C of the power transmission case 59, the radial
ball bearing 90 is supported by the inner wall portion 59C over
the entire perimeter thereof, and by mounting the radial ball
bearing 91 on the right portion of the axle 68 rightward from
the side of the space 70K of the gear case 70 rightward into
the hub portion 70B of the gear case 70, the radial ball bearing
91 is supported by the hub portion 70B over the entire perimeter
thereof.
[0052]
The radial ball bearing 87 for supporting the right
portion of the driven shaft 60 is attached to the power
transmission case 59 via a separate bearing holder 100.
Referring also Fig. 6, the bearing holder 100 includes
an annular holder body 101 which surrounds the radial ball
bearing 87, and three fixing flanges 102 extending from the
right end portion of the holder body 101 toward the outer
periphery thereof formed integrally with each other. The
respective fixing flanges 102 are disposed at substantially
regular intervals in the circumferential direction of the
holder body 101, and the bearing holder 100 is fixed to the
inner wall portion 59C when bolts 103 which penetrate through
the respective fixing flanges 102 are tightened into the inner
wall portion 59C.
[0053]
Two of the fixing flanges 102 are provided on the holder
body 101 on the side of the intermediate shaft 73 so as to be
substantially symmetry with respect to a straight line L
connecting the shaft center of the driven shaft 60 and the shaft
center of the intermediate shaft 73 in side view in Fig. 6,
and the remaining one of the flanges is provided on the holder
body 101 at the position opposite from the intermediate shaft
73. This is for preventing the fixing bolts 103 from being
disposed between the driven shaft 60 and the intermediate shaft
73.
[0054]
The holder body 101 includes an inner peripheral surface
which aligns with the outer peripheral surface of the outer
lace of the radial ball bearing 87. By mounting the radial
ball bearing 87 into the bolder body 101 by press-fitting or
the like, the radial ball bearing 87 is retained in a state
of being surrounded by the bearing holder 100 over the entire
perimeter thereof. By mounting and fixing the bearing holder
100 from the side of the space 70K of the gear case 70 leftward
into a mounting portion 94 of the inner wall portion 59C of
the power transmission case 59, the radial ball bearing 87 is
supported by the inner wall portion 59C via the bearing holder
100 over the entire perimeter thereof.
[0055]
The bearing holder 100 and the radial ball bearing 87
retained thereby are disposed so that the portion on the side
of the intermediate shaft 73 is partly overlapped with the
portion of the radial ball bearing 88 on the left end side of
the intermediate shaft 73 on the side of the driven shaft 60
when viewed in the axial direction (lateral direction). The
radial ball bearing 89 on the right end side of the intermediate
shaft 73 is a component identical to the radial ball bearing
88 on the right end side, and these ball bearings are disposed
coaxially. Therefore, the bearing holder 100 and the radial
ball bearing 87 are overlapped also with the radial ball bearing
89 in axial view.
[0056]
In addition, since the radial ball bearing 88 on the left
end side of the intermediate shaft 73 is stored in the storage
section 95 which is formed by shifting part of the inner wall
portion 59C of the power transmission case 59 leftward, the
bearing holder 100 and the radial ball bearing 87 are located
between the radial ball bearing 88 on the left end side of the
intermediate shaft 73 and the small-diameter gear 72A in the
axial direction, and the bearing holder 100 and the
general-diameter portion 73a of the intermediate shaft 73 are
disposed close to each other so that the portion of the bearing
holder 100 on the side of the intermediate shaft 73 is partly
overlapped with the maximum outer diameter portion of the
small-diameter gear 72A on the side of the driven shaft in axial
view. Consequently, the distance between the driven shaft 60
and the intermediate shaft 73 are reduced, and the diameters
of the respective gears 71A and 72B which constitute the first
speed reduction gear pair 71 for linking the driven gear 60
and the intermediate shaft 73 are reduced.
[0057]
Since the storage section 95 in which the radial ball
bearing 88 on the left end side of the intermediate shaft
are disposed is formed into a recessed shape on the inner wall
portion 59C of the power transmission case 59 when viewed from
the side of the space 70K of the gear case 70, by disposing
the radial ball bearing 88 in this storage section 95, the space
for disposing components in the space 70K of the gear case 70
can be increased. Although the storage section 95 is formed
into a projected shape on the inner wall portion 59C of the
power transmission case 59 when viewed form the space 59K of
the power transmission case 59, since the storage section 95
is provided so as to be positioned on the inner side of the
bowl-shaped driven side fixed pulley half 62a, the influence
to the space for disposing the components in the space 59K is
constrained, whereby lowering of flexibility of layout of the
stepless speed changer 23 is prevented.
[0058]
By disposing the radial ball bearing 88 axially between
the set of the bearing holder 100 and the radial ball bearing
87 and the inner wall portion 59C (the bottom wall portion of
the storage section 95), the bearing holder 100 and the radial
ball bearing 87 serve also as a stopper for preventing the
bearing holder 100 and the radial ball bearing 87 from coming
off from the storage section 95 of the radial ball bearing 88.
Since a space S is formed between the radial ball bearing 88
and the set of the bearing holder 100 and the radial ball bearing
87 in the axial direction, the part tolerance of the respective
radial ball bearings 87, 88 and the bearing holder 100 in the
axial direction, and the mounting tolerance with respect to
the inner wall portion 59C can be absorbed. The radial ball
bearing 88 which is disposed within the storage section 95
formed by shifting part of the inner wall portion 59C leftward
is disposed on the far side (that is, the left side) of the
radial ball bearing 87 in terms of the mounting direction of
the respective radial ball bearings 87, 88. In other words,
the radial ball bearing 87 is disposed on the front side (that
is, the right side) of the radial ball bearing 88 in the mounting
direction.
[0059]
Since the first embodiment employs an arrangement
structure of bearings in which the driven shaft 60 and the
intermediate shaft 73, which are disposed in substantially
parallel to each other and linked to each other are rotatably
supported via the radial ball bearings 87, 88, respectively,
and the respective radial ball bearings 87 88 are disposed so
as to be overlapped partly with each other in axial view, the
center distance between the driven shaft 60 and the
intermediate shaft 73 is reduced and diameters of the
small-diameter gear 71A and the large-diameter gear 7IB which
link the shafts 60, 73 are reduced respectively in comparison
with the case in which the respective radial ball bearings 87,
88 are disposed in a juxtaposed manner so as to extend along
the inner wall portion 59C of the power transmission case 59
which supports the respective radial ball bearings 87, 88.
Therefore, downsizing of the rear portion of the power
unit 11 including the gear case 70 is achieved, and weight
reduction by reducing the diameters of the respective gears
71A, 7IB is also achieved. In particular, in the motorcycle
1A of a unit swing type, the weight reduction of the rear portion,
which corresponds to the distal side of swinging motion of the
power unit 11 which is located below the spring, is very
effective in terms of the traveling performance of the
motorcycle 1A.
[0060]
In the arrangement structure of bearings described above,
since the respective radial ball bearings 87, 88 are mounted
from the side of the space 70K of the gear case 70 leftward
into the inner wall portion 59C which supports the radial ball
bearings 87, 88, when assembling the speed reduction mechanism
69 which includes the radial ball bearings 87, 88, the radial
ball bearings 87, 88 can be mounted to the inner wall portion
59C in the same direction. In other words, the mounting
properties of the respective radial ball bearings 87, 88 can
be improved. Since maintenance of the radial ball bearings
87, 88 can be performed in the same direction by removing the
gear case 70, maintenanceability of the respective radial ball
bearings 87, 88 can be improved.
[0061]
In the arrangement structure of bearings described above,
since the storage section 95 is formed on the inner wall portion
59C for supporting the respective radial ball bearings 87, 88
so that the radial ball bearing 88 is arranged on the far side
with respect to the radial ball bearing 87 in terms of the
mounting direction of the radial ball bearings 87, 88, when
mounting the respective radial ball bearings 87, 88 on the inner
wall portion 59C,the radial ball bearing 88 is mounted to the
inner wall portion 59C in a state in which the radial ball
bearing 88 is disposed within the storage section 95 so as to
dispose the same in the far side in terms of the mounting
direction, and then, the radial ball bearing 87 is mounted to
the inner wall portion 59C. Accordingly, the respective
radial ball bearings 87, 88 can be easily mounted, whereby
assembleability of these ball bearings can be further improved.
[0062]
Since the radial ball bearing 88 is disposed within the
recessed storage section 95, even when the positions to arrange
the radial ball bearings 87, 88 are shifted in the axial
direction so as to overlap with each other in axial view, the
space 70K in the gear case 70 is not reduced. In contrast,
since the radial ball bearing 88 is stored in the storage
section 95, the space for arranging the parts in the space 70K
can be increased. In this manner, efficient arrangement of
the radial ball bearing 88 is enabled, whereby further
downsizing of the power unit 11 including the gear case 70 is
achieved.
[0063]
Furthermore, in the arrangement structure of bearings
described above, since the bearing holder 100 for surrounding
and retaining the radial ball bearing 88 is provided, and the
radial ball bearing 88 is mounted to the inner wall portion
59C via the bearing holder 100, the radial ball bearing 88 can
be supported via the bearing holder 100 over the entire
perimeter thereof. In other words, the mounting strength of
the radial ball bearing 88 with respect to the inner wall
portion 59C can be improved.
[0064]
Furthermore, in the arrangement structure of bearings
described above, since the radial ball bearing 88 is disposed
between the set of the bearing holder 100 and the radial ball
bearing 87 and the inner wall portion 59C in the axial direction,
and the set of the radial ball bearing 88 and the bearing holder
100 and the radial ball bearing 87 are disposed so as to form
the space S in the axial direction, the part tolerance of the
respective radial ball bearings 87, 88 and the bearing holder
100 in the axial direction and the mounting tolerance with
respect to the inner wall portion 59C can be absorbed, and hence
mounting accuracy of the respective radial ball bearings 87,
88 and the bearing holder 100 can be improved.
[Second Embodiment]
[0065]
Subsequently, a second embodiment of the present
invention will be described.
In this second embodiment, since only the fact that the
bearing holder 100 is not used is different from the first
embodiment, the parts corresponding to the first embodiment
are represented by the same reference numerals and the
description will be omitted.
[0066]
As shown in Figs. 7 and 8, in the arrangement structure
of bearings according to the second embodiment, by mounting
the radial ball bearing 87 for supporting the right portion
of the driven shaft 60 to the mounting portion 94 provided on
the inner wall portion 59C of the power transmission case 59
leftward from the side of the space 70K of the gear case 70
by press-fitting or the like, the radial ball bearing 87 is
supported by the inner wall portion 59C. The portion of the
radial ball bearing 87 on the side of the intermediate shaft
73 is disposed so as to overlap partly with the radial ball
bearing 88 on the left end side of the intermediate shaft 73
in axial view.
[0067]
In the same manner as the first embodiment, the radial
ball bearing 88 is disposed between the radial ball bearing
87 and the inner wall portion 59C (the bottom wall portion of
the storage section 95) in the axial direction. In addition,
a space S' is formed between the respective radial ball bearings
87, 88. Furthermore, the radial ball bearing 88 disposed
within the storage section 95 is disposed on the far side with
respect to the radial ball bearing 87 in the mounting direction
of the radial ball bearings 87, 88.
[0068]
In the arrangement structure of bearings according to
the second embodiment as well, as in the first embodiment, the
assembleability of the radial ball bearings 87, 88 is improved
and maintenanceability of the speed reduction mechanism 69 is
improved in addition to the achievement of weight reduction
by downsizing of the rear portion of the power unit 11 including
the gear case 70 and reduction of the diameters of the
respective gears 71A, 7IB. Also, mounting accuracy of the
radial ball bearings 87, 88 can be improved by absorbing the
part tolerance of the radial ball bearings 87, 88 in the axial
direction and the mounting tolerance thereof with respect to
the inner wall portion 59C.
[0069]
The invention is not limited to the embodiments described
above and, for example, the mounting strength of the radial
ball bearing 88 with respect to the inner wall portion 59C can
be improved by eliminating the space S or S' between the radial
ball bearings 87, 88 and interposing the radial ball bearing
88 between the radial ball bearing 87 and the inner wall portion
59C (the bottom wall portion of the storage section 95) in the
axial direction, the mounting strength of the radial ball
bearing 88 with respect to the inner wall portion 59C can be
improved.
In addition, as long as a structure is such that the
respective bearings are partly overlapped in axial view between
the radial ball bearing 88 which supports the intermediate
shaft 73 and the radial ball bearing 90 which supports the axle
68, or between the radial ball bearings 86, 89 which are mounted
to the bottom wall portion 70C of the gear case 70, the
arrangement structure of bearings as described above can be
applied.
Furthermore, when using the bearing holder 100, for
example, fixation by press-fitting or the like may be employed
besides the fixation to the gear case 70 using a bolt.
Alternatively, a structure in which the storage section 95 is
a recess formed in the vicinity thereof for simply shifting
the radial ball bearing 88 leftward, and the radial ball bearing
88 is supported by other supporting means.
The structures in the respective embodiments are shown
simply for illustration, and various modifications may be made
without departing from the scope of the invention, as a mater
of course.
[Reference Numerals]
[0071]
59C inner wall portion (wall portion)
60 driven shaft (power transmission shaft)
73 intermediate shaft (power transmission shaft)
87 radial ball bearing (second bearing)
88 radial ball bearing (first bearing)
95 storage section (recessed portion)
100 bearing holder (bearing holder)

We claim:
1. An arrangement structure for bearings comprising:
a plurality of power transmission shafts (60) positioned in a substantially parallel arrangement relative to each other, the power transmission shafts (60) being rotatably supported via bearings, respectively, and arranged so that the bearings overlap partly with each other in an axial view; whereby a center-to-center distance between the power transmission shafts (60) can be minimized;
a wall portion (59C) having a surface facing a space in which the power transmission shafts (60) are disposed and being formed with a recess that is axially displaced from an adjacent region of the wall portion (59C), the bearings being mounted to the surface of the wall portion (59C) substantially in the same direction;
a second bearing (87) contacts the wall portion (59C) in the axial direction at the adjacent region; and
a first bearing (88) contacts the recess in the axial direction, whereby the first bearing (88) is disposed on the far side of the second in terms of the mounting direction of the bearings.
2. The arrangement structure for bearings as claimed in claim 1, wherein a bearing holder (100) is provided for surrounding and retaining the second bearing (87), and the second bearing (87) is mounted to the wall portion (59C) via the bearing holder (100).
3. The arrangement structure for bearings as claimed in claim 2, wherein the first bearing (88) is disposed between the second bearing (87) and the wall portion (59C) in the axial direction.

4. The arrangement structure for bearings as claimed in claim 2, wherein a space is formed between the first bearing (88) and the second bearing (87) in the axial direction.
5. The arrangement structure for bearings as claimed in claim 1, wherein the first bearing (88) is disposed between the second bearing (87) and the wall portion (59C) in the axial direction.
6. The arrangement structure for bearings as claimed in claim 5, wherein a space is formed between the first bearing (88) and the second bearing (87) in the axial direction.
7. The arrangement structure for bearings as claimed in claim 1, wherein a space is formed between the first bearing (88) and the second bearing (87) in the axial direction.
8. An arrangement structure for bearings comprising:
a plurality of power transmission shafts (60) positioned to be rotatably supported via bearings, respectively, and arranged so that the bearings overlap partly with each other in an axial view, whereby a center-to-center distance between the power transmission shafts (60) can be minimized;
a wall portion (59C) for supporting a first bearing (88) for rotatably supporting a first power transmission shaft;
said wall portion (59C) supports a second bearing (87) for rotatably supporting a second power transmission shaft;

said wall portion (59C) having a surface facing a space in which the power transmission shafts (60) are disposed and being formed with a recess that is axially displaced from an adjacent region of the wall portion (59C) ,
said first and second bearing (87) s being mounted to the surface of the wall portion (59C) substantially in the same direction;
the second bearing (87) contacts the wall portion (59C) in the axial direction at the adjacent region:
and the first bearing (88) contacts the recess in the axial direction, whereby the first bearing (88) is disposed on the far side of the second bearing (87) in terms of the mounting direction of the bearings.
9. The arrangement structure for bearings as claimed in claim 8, wherein a bearing holder (100) is provided for surrounding and retaining the second bearing (87) and the second bearing (87) is mounted to the first wall portion (59C) via the bearing holder (100).
10. The arrangement structure for bearings as claimed in claim 9, wherein the first bearing (88) is disposed between the second bearing (87) and the wall portion (59C) in the axial direction.
11. The arrangement structure for bearings as claimed in claim 9, wherein a space is formed between eh first bearing (88) and the second bearing (87) in the axial direction.
12. The arrangement structure for bearings as claimed in claim 8, wherein the first bearing (88) is disposed between the second bearing (87) and the wall portion (59C) in the axial direction.

13. The arrangement structure for bearings as claimed in claim 12, wherein a space is formed between the first bearing (88) and the second bearing (87) in the axial direction.
14. The arrangement structure for bearing as claimed in claim 8, wherein a space is formed between eh first bearing (88) and the second bearing (87) in the axial direction.

Documents:

10-DEL-2005-Abstract-(01-12-2009).pdf

10-DEL-2005-Abstract-(07-08-2009).pdf

10-DEL-2005-Abstract-(10-09-2008).pdf

10-del-2005-Abstract-(30-12-2009).pdf

10-del-2005-abstract.pdf

10-DEL-2005-Claims-(01-12-2009).pdf

10-DEL-2005-Claims-(07-08-2009).pdf

10-DEL-2005-Claims-(10-09-2008).pdf

10-del-2005-Claims-(30-12-2009).pdf

10-del-2005-claims.pdf

10-DEL-2005-Correspondence-Others-(10-09-2008).pdf

10-DEL-2005-Correspondence-Others-(18-09-2008).pdf

10-del-2005-Correspondence-Others-(30-12-2009).pdf

10-del-2005-correspondence-others.pdf

10-del-2005-description (complete)-10-09-2008.pdf

10-del-2005-description (complete).pdf

10-del-2005-drawings.pdf

10-del-2005-Form-1-(30-12-2009).pdf

10-del-2005-form-1.pdf

10-del-2005-form-19.pdf

10-del-2005-Form-2-(30-12-2009).pdf

10-del-2005-form-2.pdf

10-DEL-2005-Form-3-(10-09-2008).pdf

10-del-2005-form-3.pdf

10-DEL-2005-Form-5-(10-09-2008).pdf

10-del-2005-form-5.pdf

10-DEL-2005-GPA-(10-09-2008).pdf

10-del-2005-gpa.pdf

10-DEL-2005-Petition-138-(18-09-2008).pdf

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Patent Number

235196

Indian Patent Application Number

10/DEL/2005

PG Journal Number

31/2009

Publication Date

31-Jul-2009

Grant Date

27-Jun-2009

Date of Filing

03-Jan-2005

Name of Patentee

HONDA MOTOR CO. LTD.

Applicant Address

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

Inventors:

#	Inventor's Name	Inventor's Address
1	YOSHIAKI TSUKADA,	C/O KABUSHIKI KAISHA HONDA GIJUTSU KENKYUSHO, 4-1 CHOU 1-CHOME, WAKO-SHI, SAITAMA, JAPAN.
2	TAKASHI OZEKI	C/O KABUSHIKI KAISHA HONDA GIJUTSU KENKYUSHO, 4-1 CHUO 1-CHOME, WAKO-SHI, SAITAMA, JAPAN.
3	SHINJI FURUTA	C/O KABUSHIKI KAISHA HONDA GIJUTSU KENKYUSHO, 4-1 CHUO 1-CHOME, WAKO-SHI, SAITAMA, JAPAN.

PCT International Classification Number

F16C17/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA