JP2014162345A - Gear box structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve downsizing and weight reduction while maintaining mechanical performance in a gear box structure which transmits a driving force from a power unit to a driving shaft.SOLUTION: A gear box structure includes: a support wall 46 which is provided in a final gear case 31 arranged substantially perpendicular to an axial direction of a pinion gear 27 at the ring gear side in the axial direction; a support pin 47 which is provided at the support wall 46 and protrudes toward the pinion gear 27 coaxially with the pinion gear 27; a recessed part 32c which is formed at the inner peripheral side of the pinion gear 27 and into which the support pin 47 may be inserted; and a radial needle bearing 45 which is stored in the recessed part 32c and causes the support pin 47 to support the pinion gear 27.

Description

  The present invention relates to a gear box structure.

Conventionally, a drive shaft that transmits driving force from a power unit, a pinion gear that is connected to the drive shaft and transmits driving force, a ring gear that meshes with the pinion gear and transmits driving force to the drive shaft, and a pinion gear and a ring gear are accommodated. A gear box structure including a gear case is known.
Patent Document 1 discloses a gear case in which a support wall substantially orthogonal to the axial direction of the pinion gear is provided, and the pinion gear is rotatably supported by the support wall.

JP 2009-220786 A

  By the way, in recent years, for the purpose of improving the fuel efficiency and reducing the material cost, it is desired to reduce the weight of the vehicle without reducing the mechanical performance. The final gearbox that transmits the driving force from the power unit to the axle is no exception, and a reduction in size and weight is desired while maintaining mechanical performance.

  Accordingly, an object of the present invention is to reduce the size and weight of the gear box structure that transmits the driving force from the power unit to the driving shaft while maintaining the mechanical performance.

As a means for solving the above-mentioned problem, the invention described in claim 1 includes a drive shaft (24) for transmitting a driving force from a power unit (20), and a pinion gear connected to the drive shaft (24) for transmitting the driving force. (27), a ring gear (34) for transmitting a driving force to the pinion gear (27) and the meshing drive shaft (25), and a gear case (31) for housing the pinion gear (27) and the ring gear (34). In the gear box structure, a support wall (46) provided substantially perpendicular to the axial direction on the ring gear (34) side in the axial direction of the pinion gear (27) in the gear case (31), and the support wall (46 ) And a projection (47) that projects coaxially with the pinion gear (27) toward the pinion gear (27), and the pinion gear A recess (32c) formed on the inner peripheral side of (27) to allow the protrusion (47) to be inserted, and a pinion gear (27) accommodated in the recess (32c) in the protrusion (47). And a gear bearing (45) for supporting the shaft.
According to a second aspect of the present invention, in the gear bearing (45), one end in the axial direction is in contact with the step portion (32d) in the recess (32c), and the other end in the axial direction is a gap between the support wall (46). It is characterized in that (cl) is left close.
The invention described in claim 3 has a protrusion (42) that can be inserted inside an end (38) on the drive shaft (24) side of the gear case (31), and the protrusion (42) is provided. A swing arm (9) fastened to the gear case (31) in the inserted state; a second bearing (39) for supporting the swing arm (9) side of the pinion gear (27) on the gear case (31); And the protrusion (42) is in contact with or pressed against the second bearing (39) directly or indirectly.
The invention described in claim 4 is characterized in that the protrusion (42) abuts against and presses the second bearing (39) via an elastic member (43).
According to a fifth aspect of the present invention, there is provided a drive bearing (54) for supporting one end portion of the drive shaft (25) on the gear case (31), and one end portion of the drive shaft (25) in the gear case (31). A lid member (56) fastened to the gear case (31) in a state in which the opening (55) formed at the facing portion is closed and in direct contact with the drive bearing (54). It is characterized by that.

According to the first aspect of the present invention, the dimensional limit of the support wall is reduced as compared with the case where the gear bearing is accommodated in the support wall. Therefore, if the rigidity of the protruding portion can be ensured, the thickness of the support wall is reduced. It becomes possible. For this reason, after supporting the pinion gear on the support wall, the pinion gear can be brought close to the support wall side. As a result, the ring gear can also be reduced in size, and the gear box structure can be reduced in size and weight.
According to the second aspect of the present invention, the axial movement of the gear bearing in the recess can be restricted by the arrangement of the components, and the weight reduction can be further achieved with a simple structure for preventing the gear bearing from coming off.
According to the invention described in claims 3 and 4, the retaining of the second bearing to the swing arm side can be realized with a simple structure such as a protrusion of the swing arm, and a bearing support member need not be provided separately. The number of parts can be reduced. According to the invention described in claim 5, the lid member and the screw lock agent can realize the retaining and sealing function of the drive bearing, and the weight can be reduced by reducing the number of parts. .

1 is a left side view of a motorcycle according to an embodiment of the present invention. It is a left view of the rear-wheel drive mechanism of the said motorcycle. It is III-III sectional drawing of FIG. FIG. 4 is an operation explanatory diagram in which the first main part of FIG. 3 is arranged with a comparative example. It is action explanatory drawing which arranged the 2nd principal part of FIG. 3 with the comparative example. FIG. 10 is an operation explanatory diagram in which a third main part of FIG. 3 is arranged with a comparative example.

  Embodiments of the present invention will be described below with reference to the drawings. Note that the directions such as front, rear, left and right in the following description are the same as those in the vehicle described below unless otherwise specified. Further, in the drawings used for the following explanation, an arrow FR indicating the front of the vehicle, an arrow LH indicating the left side of the vehicle, and an arrow UP indicating the upper side of the vehicle are shown.

In the motorcycle 1 shown in FIG. 1, the front wheel 2 is pivotally supported at the lower ends of a pair of left and right front forks 3, and the upper portion of each front fork 3 is operated by a head pipe 6 at the front end of a vehicle body frame 5 via a steering stem 4. It is pivotally supported. A steering handle 4 a is attached on the steering stem 4.
On the rear side of the head pipe 6 of the vehicle body frame 5, left and right main frames 7 extend obliquely downward and rearward. Below the rear end of the left and right main frame 7, a left and right pivot frame 8 extends downward. A front end portion of a cantilever swing arm 9 is pivotally supported on the left and right pivot frame 8 so as to be vertically swingable. A final gear box 30 is connected to the rear end 9 b of the left cantilever arm 9 a of the swing arm 9, and the rear wheel 11 is pivotally supported on the right side of the final gear box 30. A drive shaft 24 (see FIG. 2) for transmission between the rear wheel 11 and the power unit 20 inside the vehicle body frame 5 is inserted into the left cantilever arm 9a.

  The power unit 20 is, for example, a water-cooled four-stroke V-type four-cylinder engine having a crankshaft along the vehicle body left-right direction (vehicle width direction). The power unit 20 may be an internal combustion engine having another configuration, and may include an electric motor instead of the internal combustion engine.

  In the figure, reference numeral 12 denotes a pivot shaft that supports the front end portion of the swing arm 9, reference numeral 13 denotes a link mechanism that extends between the front lower side of the swing arm 9 and the lower end portion of the left and right pivot frames 8, and reference numeral 13a denotes the link mechanism 13 and the left and right pivots. A rear cushion over the upper end of the frame 8, a reference numeral 15 is a seat on which an occupant is seated, a reference numeral 16 is a fuel tank disposed in front of the seat 15, a reference numeral 18 is a front cowl covering the front of the vehicle body, and a reference numeral 19 is a rear part of the vehicle Each shows a rear cowl that covers.

  As shown in FIG. 2, the rear wheel drive mechanism 21 of the motorcycle 1 is connected to the output shaft 22 of the power unit 20 to transmit a driving force, and to the rear end portion of the universal joint 23 to be connected to the power unit. A drive shaft 24 that transmits a driving force of 20, a shaft length variable mechanism 26 that is connected to a rear end portion of the drive shaft 24 so that the shaft length of the drive shaft 24 can be changed, and a left side behind the shaft length variable mechanism 26 And a final gear box 30 connected to the rear end portion 9b of the cantilever arm 9a. The universal joint 23, the drive shaft 24, and the variable shaft length mechanism 26 are disposed in the hollow left cantilever arm 9a.

  In the present embodiment, the variable shaft length mechanism 26 uses a tripod type constant velocity joint, but is not limited to this, and may be a ball spline slide joint, a cross groove type joint, or the like. It is not limited to.

  The rear end 9b of the left cantilever arm 9a of the swing arm 9 is connected to the front end of a final gear case 31 that houses the rear wheel axle 25 and its peripheral drive system parts in the final gear box 30. In the figure, reference numeral 28 denotes a brake disk that rotates integrally with the rear wheel 11, and reference numeral 29 denotes a caliper that clamps the brake disk 28.

Referring also to FIG. 3, the final gear case 31 includes a pinion gear shaft 32 having an axial line C2 extending in the front-rear direction, and a rear wheel axle 25 having an axis C1 parallel to the left-right direction and perpendicular to the axial line C2. Housed in the rear.
A pinion gear 27 is provided at the rear portion of the pinion gear shaft 32 so as to be integrally rotatable, for example, by integral formation. A ring gear 34 that meshes with the pinion gear 27 is provided on the left and right intermediate portion 25b of the rear wheel axle 25 so as to be integrally rotatable by, for example, spline fitting. The pinion gear 27 and the ring gear 34 constitute a bevel gear pair 34 </ b> A that transmits power between the pinion gear shaft 32 and the rear wheel axle 25.

  The rotational driving force of the power unit 20 transmitted to the pinion gear shaft 32 through the drive shaft 24 and the like is transmitted to the rear wheel axle 25 after being decelerated and changed in direction through the bevel gear pair 34A. The center portion of the wheel 11a of the rear wheel 11 is fastened to the right end portion of the rear wheel axle 25 by using, for example, a stud bolt B1 standing upright. The rear wheel axle 25 drives the motorcycle 1 by driving the rear wheel 11 with the transmitted driving force of the power unit 20.

  The final gear case 31 is divided into a left case body 36 that supports the pinion gear shaft 32 and the left end portion of the rear wheel axle 25, and a right case body 37 that supports the right side portion 25 c of the rear wheel axle 25. The left case body 36 forms a rear right open portion 36a, and the left open portion 37a of the right case body 37 is fastened to the rear right open portion 36a by a bolt B2. In the figure, reference numeral 36b denotes a plug that closes the gear oil inlet at the rear of the left case body 36.

  An inner race 39a of a radial ball bearing 39 that rotatably supports the front and rear intermediate portions of the pinion gear shaft 32 in the front end opening portion 38 of the final gear case 31 is fitted. The inner race 39a of the radial ball bearing 39 is brought into contact with the front end stepped surface 27a of the pinion gear 27 whose diameter is enlarged at the rear portion of the pinion gear shaft 32 through the shim sm1, and the front end is brought into contact with the rear end of the yoke member 41. Let

  The yoke member 41 has a cylindrical shape, and a rear portion thereof is externally fitted to the front portion of the pinion gear shaft 32 by a spline so that a rear connection shaft (not shown) of the shaft length variable mechanism 26 can be connected to the front portion. In the yoke member 41, a front end screw shaft 32a of the pinion gear shaft 32 and a nut 32b screwed to the front end screw shaft 32a are arranged. By tightening the front end screw shaft 32a and the nut 32b, the rear portion of the yoke member 41 and the inner race 39a of the radial ball bearing 39 are sandwiched between the nut 32b and the pinion gear 27 and are supported by the rear wheel axle 25 so as to be integrally rotatable. The

  The rear end portion 9b of the left cantilever arm 9a of the swing arm 9 is fastened to the front end opening portion 38 of the final gear case 31 by using, for example, a stud bolt B3 that rises forward from the front end opening portion 38 of the final gear case 31. . In the figure, reference numeral 9c denotes a fastening flange formed on the outer periphery of the rear end portion 9b, and reference numeral N3 denotes a nut screwed to the stud bolt B3.

  An annular protrusion 42 that protrudes rearward from the rear end portion 9b of the left cantilever arm 9a is fitted into the front end opening portion 38 of the final gear case 31. The annular protrusion 42 abuts the rear end thereof against the ring-shaped disc spring 43. The disc spring 43 contacts the front end of the outer race 39 b of the radial ball bearing 39. The rear end of the outer race 39b comes into contact with the front surface of the inner flange portion 44 in the final gear case 31 from the front.

  In this state, by fastening the rear end portion 9b of the left cantilever arm 9a to the front end opening portion 38 of the final gear case 31, the annular protrusion 42 presses the outer race 39b rearward via the disc spring 43, and the outer race 39b. Is fixedly supported in the front end opening 38 of the final gear case 31. In the figure, reference numeral sl1 is a seal member fitted between the inner periphery of the rear end 9b of the left cantilever arm 9a and the outer periphery of the yoke member 41, and reference numeral sl2 is attached to the outer periphery of the annular protrusion 42 so as to open the front end. Each of the O-rings closely contacting the inner periphery of the portion 38 is shown.

  The pinion gear shaft 32 and the yoke member 41 protrude from the front end opening portion 38 of the final gear case 31 to the front of the case. The rear portion of the pinion gear shaft 32 is made hollow by forming a recess 32 c on the inner periphery of the pinion gear 27. The recess 32c is opened rearward, and a radial needle bearing 45 is fitted into the recess 32c. In the figure, reference numeral 45b denotes a retainer for holding the needle 45a in the radial needle bearing 45.

  The front and rear ends of the retainer 45 b are front and rear ends of the radial needle bearing 45, the front end of the retainer 45 b abuts on the step surface 32 d on the front side of the recess 32 c, and the rear end of the retainer 45 b has a gap cl on the front surface 46 b of the support wall 46. Is arranged (see FIG. 4). The clearance cl is sufficiently smaller than the axial width of the radial needle bearing 45, and the radial needle bearing 45 is prevented from coming off from the recess 32c in the assembled state shown in FIG.

  The rear end of the pinion gear shaft 32 faces the front surface 46 b of the support wall 46 erected in the final gear case 31. The support wall 46 is disposed behind the pinion gear shaft 32 so as to be orthogonal to the axis C2. A support pin 47 is fixed to the support wall 46 so as to penetrate the support wall 46 from the rear and project forward. The front portion of the support pin 47 is fitted into the radial needle bearing 45. The radial needle bearing 45 rotatably supports the rear portion of the pinion gear shaft 32 on the support pin 47.

  The rear wheel axle 25 has a full length that fits in the left and right width of the final gear case 31. The left side portion 25 a of the rear wheel axle 25 is formed with a smaller diameter than the left and right intermediate portion 25 b that supports the ring gear 34. The support wall 46 is adjacent to the front side of the left side portion 25a of the rear wheel axle 25. The right side portion 25c of the rear wheel axle 25 is formed with a larger diameter than the left and right intermediate portion 25b. An enlarged flange portion 25d having a larger diameter is formed at the left end of the right portion 25c. The right end of the ring gear 34 comes into contact with the left side surface of the diameter-enlarged flange portion 25d, and the rightward movement of the ring gear 34 is restricted.

  The outer periphery of the right side portion 25 c is supported on the inner periphery of the rear right side of the final gear case 31 through a bearing pair 48 </ b> A including a pair of left and right radial ball bearings 48, for example. On the right side of the rear portion of the final gear case 31, a right end opening portion 49 that opens to the right is formed. The right end portion of the rear wheel axle 25 faces the right end opening portion 49, and a flange member 51 for supporting the brake disc 28 is fastened to the right end portion with a screw B5. The flange member 51 has a fastening boss 51a for the brake disc 28 formed on the outer periphery thereof. Reference numeral 52 in the drawing denotes a pulsar ring for a wheel speed sensor fastened to the left side surface of the flange member 51 by a screw B4.

  On the left side of the flange member 51, a cylindrical collar portion 51b that enters the right end opening portion 49 of the final gear case 31 is formed. The left end of the collar portion 51b is brought into contact with the right end of the inner race 48a of the bearing pair 48A. The left end of the inner race 48a of the bearing pair 48A is in contact with the left side surface of the diameter-enlarged flange portion 25d of the rear wheel axle 25 via a shim sm2.

  When the flange member 51 is fastened to the rear wheel axle 25 with the screw B5, the inner race 48a of the bearing pair 48A is clamped between the collar portion 51b and the enlarged diameter flange portion 25d and fixed to the rear wheel axle 25. The right end of the outer race 48b of the bearing pair 48A abuts on the left side surface of the positioning flange 53 on the inner periphery of the right end opening portion 49. In the figure, reference numeral sl3 is a seal member fitted to the right of the positioning flange 53 between the right end opening 49 and the collar part 51b, reference numeral sn is a snap ring for preventing the seal member sl3 from coming off, and reference numeral sl4 is a rear axle. Each of the O-rings is attached to the outer periphery of the right end portion of 25 and closely contacts the inner periphery of the collar portion 51b.

  A shaft support portion 25e having a smaller diameter is formed at the left end portion of the rear wheel axle 25. A radial ball bearing 54 is fitted on the shaft support 25e. The radial ball bearing 54 is fitted in a left end opening 55 on the left side of the rear portion of the final gear case 31, and rotatably supports the shaft support portion 25 e of the rear wheel axle 25 in the left end opening portion 55 of the final gear case 31.

  The left end opening part 55 is closed by a disk-shaped cap bolt 56. The cap bolt 56 is tightened by screwing its outer peripheral screw with the inner peripheral screw of the left end opening portion 55. For example, a screw lock agent is applied to the outer periphery of the cap bolt 56 to seal the left end opening 55. The right side surface of the outer periphery of the cap bolt 56 is in contact with the left end of the outer race 54 b of the radial ball bearing 54. The right end of the outer race 54 b abuts on the left step surface 57 in the final gear case 31. Accordingly, the outer race 54 b is fixed in the left end open portion 55 of the final gear case 31 by tightening the cap bolt 56 in the left end open portion 55. The right end of the inner race 54a of the radial ball bearing 54 is in contact with the stepped surface 25f of the base end portion 25e of the outer periphery of the rear wheel axle 25 via the shim sm3.

4 to 6 are explanatory diagrams of the operation of the present embodiment.
In the comparative example shown in the lower part of FIG. 4, a recess 32c is not formed in the rear part of the pinion gear shaft 32, but instead a support shaft 47 'protruding rearward is fixed to the upper example of the present embodiment. 'Is supported by a support wall 46' in place of the support wall 46. The support wall 46 ′ is formed with a recess 32c ′ that accommodates the radial needle bearing 45, and the support shaft 47 ′ is supported by the radial needle bearing 45 fitted inside the recess 32c ′.

  In the comparative example of FIG. 4, the longitudinal width of the support wall 46 ′ cannot be made smaller than the axial width of the radial needle bearing 45. On the other hand, in this embodiment, if the support rigidity of the support pins 47 can be secured, the front-rear width of the support wall 46 can be made smaller than that of the comparative example. Therefore, when the front and rear positions of the rear surfaces 46a and 46a ′ of the support walls 46 and 46 ′ are compared and compared, the front end position of the pinion gear shaft 32 of the present embodiment is S1 in the figure than the front end position of the pinion gear shaft 32 of the comparative example. The rear wheel drive mechanism 21 can be made smaller and lighter.

  In the comparative example shown on the right side of FIG. 5, the right side surface of the outer peripheral portion of the cap bolt 56 is not brought into contact with the outer race 54b of the radial ball bearing 54, and a ring-shaped inner bolt 56a is screwed instead. The outer race 54b is fixed by wearing. The cap bolt 56 ′ of the comparative example is a simple cap member, and the outer peripheral flange 56 b that holds the O-ring is brought into contact with the peripheral edge portion of the left end opening portion 55 without applying a screw lock agent as in this embodiment.

  In contrast to the comparative example of FIG. 5, in this embodiment, the outer position of the left end opening portion 55 can be displaced to the left and right inward by the amount corresponding to the elimination of the inner bolt 56a. Contributes to

  In the comparative example shown in the lower part of FIG. 6, the annular protrusion 42 and the disc spring 43 are eliminated from the upper part of this embodiment, and an annular lock bolt 142 is screwed into the front end opening part 38 instead. The 39 outer races 39b are fixed. In this case, a front and rear space for screwing the lock bolt 142 is required at the front end opening portion 38, and the abutting surface (connection surface) J between the front end opening portion 38 and the left cantilever arm 9a moves forward. In the figure, reference numeral sl1 ′ is a seal member fitted between the inner periphery of the lock bolt 142 and the outer periphery of the yoke member 41, and reference numeral sl2 ′ is attached to the outer periphery of the lock bolt 142 and closely contacts the inner periphery of the front end opening portion 38. Each ring is shown.

  In contrast to the comparative example of FIG. 6, in this embodiment, the number of parts can be reduced by eliminating the lock bolt 142. Further, the abutting surface J between the front end opening portion 38 and the left cantilever arm 9a can be retracted by S3 in the drawing as much as the space before and after the lock bolt 142 is screwed, and the rear wheel drive mechanism 21 is small and light. Contributes to

  As described above, the final gear structure in the above embodiment is engaged with the drive shaft 24 that transmits the driving force from the power unit 20, the pinion gear 27 that is connected to the drive shaft 24 and transmits the driving force, and the pinion gear 27. A ring gear 34 that transmits driving force to the rear wheel axle 25, a final gear case 31 that houses the pinion gear 27 and the ring gear 34, and a support that is provided in the final gear case 31 on the ring gear side of the pinion gear 27 in the axial direction substantially perpendicular to the axial direction. A wall 46, a support pin 47 provided on the support wall 46 and projecting coaxially with the pinion gear 27 toward the pinion gear 27, and a recess 32 c formed on the inner peripheral side of the pinion gear 27 and into which the support pin 47 can be inserted, The pinion gear is housed in the recess 32c and attached to the support pin 47. 7 a radial needle bearing 45 for supporting the one in which comprises a.

  According to this configuration, since the dimensional limit of the support wall 46 is reduced as compared with the case where the radial needle bearing 45 is accommodated in the support wall 46, the thickness of the support wall 46 can be increased if the support rigidity of the support pin 47 can be secured. It becomes possible to reduce. For this reason, after supporting the pinion gear 27 on the support wall 46, the pinion gear 27 can be brought close to the support wall 46 side. As a result, the ring gear 34 can also be reduced in size, and the final gear structure can be reduced in size and weight. .

  In the final gear structure, the radial needle bearing 45 has a front end in contact with the stepped surface 32d in the recess 32c and a rear end close to the support wall 46 with a gap cl therebetween, so that the radial needle in the recess 32c is arranged depending on the component arrangement. The axial movement of the bearing 45 can be restricted, and the radial needle bearing 45 can be prevented from coming off with a simple structure to further reduce the weight.

  The final gear structure has an annular protrusion 42 that can be inserted inside the front end opening 38 on the drive shaft 24 side of the final gear case 31, and the swing that is fastened to the final gear case 31 with the annular protrusion 42 inserted. The arm 9 and a radial ball bearing 39 that supports the final gear case 31 on the swing arm 9 side of the pinion gear 27 are provided, and the annular protrusion 42 abuts against the radial ball bearing 39 via the disc spring 43 and presses it. Thus, the radial ball bearing 39 can be prevented from coming off to the swing arm 9 with a simple structure such as the annular protrusion 42 and the disc spring 43 of the swing arm 9, and a bearing support member need not be provided separately. Can be reduced

  The final gear structure closes a radial ball bearing 54 that supports one end portion of the rear wheel axle 25 on the final gear case 31 and a left end opening portion 55 formed at a portion of the final gear case 31 facing the left end portion of the rear wheel axle 25. In addition, the cap bolt 56 that is fastened to the final gear case 31 while being in contact with the radial ball bearing 54 is provided, so that the radial ball bearing 54 can be prevented from being detached and sealed by the cap bolt 56 and the screw lock agent. The weight can be reduced by reducing the number of parts.

  Note that the present invention is not limited to the above-described embodiment. For example, a protruding portion instead of the support pin 47 may be integrally formed on the support wall 46. The support wall 46 may be separated from the final gear case 31 so as to be detachable. The ring gear 34 may transmit a driving force to another axle. Each bearing in the embodiment may use different rolling elements or support loads in a plurality of directions.

  The radial ball bearing 39 may be pressed by an elastic member instead of the disc spring 43. The annular protrusion 42 may contact and press against the radial ball bearing 39 without an elastic member. Various shapes of protrusions instead of the annular protrusion 42 may be used. The cap bolt 56 may abut against and press the radial ball bearing 54 via an elastic member. Instead of the cap bolt 56 screwed into the inner peripheral screw of the left end opening portion 55, a lid member fastened by a screw inserted in the direction of the axis C1 may be used.

The present invention may be applied not only to motorcycles (including motorbikes and scooter type vehicles) but also to three-wheeled vehicles (including front-wheel and rear-wheel vehicles as well as front-wheel and rear-wheel vehicles) or four-wheel vehicles.
And the structure in the said embodiment is an example of this invention, A various change is possible in the range which does not deviate from the summary of the said invention.

9 Swing arm 20 Power unit 24 Drive shaft 25 Rear wheel axle (drive shaft)
27 Pinion gear 31 Final gear case (gear case)
32c Concave part 32d Step surface (step part)
34 Ring gear 38 Front end opening (end)
39 Radial ball bearing (second bearing)
42 Annular protrusion (protrusion)
43 Disc spring (elastic member)
45 Radial needle bearing (gear bearing)
46 Support wall 47 Support pin (protrusion)
54 Radial ball bearing (drive bearing)
55 Left end opening (opening)
56 Cap bolt (lid member)
cl gap

Claims (5)

A drive shaft (24) for transmitting a driving force from the power unit (20);
A pinion gear (27) connected to the drive shaft (24) to transmit a driving force;
A ring gear (34) for transmitting a driving force to the pinion gear (27) and the meshing drive shaft (25);
In a gear box structure provided with a gear case (31) for accommodating the pinion gear (27) and the ring gear (34),
A support wall (46) provided substantially perpendicular to the axial direction on the ring gear (34) side in the axial direction of the pinion gear (27) in the gear case (31);
A protrusion (47) provided on the support wall (46) and protruding coaxially with the pinion gear (27) toward the pinion gear (27);
A recess (32c) formed on the inner peripheral side of the pinion gear (27) to allow the protrusion (47) to be inserted;
A gear box structure comprising: a gear bearing (45) received in the recess (32c) and supporting the pinion gear (27) on the protrusion (47).   One end in the axial direction of the gear bearing (45) abuts on the step (32d) in the recess (32c), and the other end in the axial direction approaches the support wall (46) with a gap (cl) therebetween. The gear box structure according to claim 1. The gear case (31) has a protrusion (42) that can be inserted inside an end (38) on the drive shaft (24) side of the gear case (31), and the gear case (31) is inserted with the protrusion (42) inserted. A swing arm (9) fastened to
A second bearing (39) supporting the swing arm (9) side of the pinion gear (27) to the gear case (31),
The gearbox structure according to claim 1 or 2, wherein the protrusion (42) abuts against and presses the second bearing (39) directly or indirectly.   The gearbox structure according to claim 3, wherein the protrusion (42) contacts and presses against the second bearing (39) via an elastic member (43). A drive bearing (54) for supporting one end of the drive shaft (25) on the gear case (31);
The gear case (31) closes an opening (55) formed at a portion where one end of the drive shaft (25) faces and is in direct or indirect contact with the drive bearing (54). The gear box structure according to any one of claims 1 to 4, further comprising a lid member (56) fastened to (31).

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