JPS6144956Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a rear wheel drive system for a shaft drive type motorcycle, and when it comes to the input end member of the rear wheel, the coupling is attached to the boss of the rear wheel with the required high assembly precision ( concentricity)
The purpose is to allow it to be installed.

First, a conventional structure will be explained with reference to FIG. 1st
The figure is a horizontal sectional view of the rear wheel support, with arrow F indicating the front of the motorcycle. The line o ₁ is the center of the vehicle body, and the line o ₂ is the center of the drive shaft. The swing arm rotates about the fulcrum in a vertical direction that is approximately perpendicular to the plane of the drawing in FIG. A boss 4 of a rear wheel 3 is rotatably supported on the rear axle 1 via a pair of ball bearings 2, and therefore the boss 4 is held concentrically with respect to the rear axle 1. The boss 4 has an annular space 8 consisting of inner and outer cylindrical parts 5 and 6 and a disc part 7 that integrally connects these parts.
The right half of the cylindrical part 5 on the disk part 7 side is thickened, and the machined cylindrical outer circumferential surface 9 has a
An inner circumferential surface 1 formed by machining a cylindrical portion 11 of a coupling ring 10 that serves as an input end member for the rear wheel 3.
2 are closely fitted with a slight gap _k1 , and the concentricity of the coupling ring 10 with respect to the rear end boss 4 is maintained. The O-ring 13 (fixing elastic body) fits into the annular groove provided on the outer peripheral surface 9, and the O-ring 13
is in pressure contact with the inner circumferential surface 12 of the coupling ring. The outer circumferential surface 14 of the coupling ring 10 faces the inner circumferential surface ₁₅ of the cylindrical portion with a gap k ₂ larger than the above-mentioned gap k 1 , and the fixing member 1 is inserted into the annular groove provided in the inner circumferential surface 15 .
By fitting 7 (snap ring), the coupling ring 10 is prevented from coming off. boss 4
Radial blades 18 protrude from the cylindrical part 6 and disc part 7 into the space 8 at equal intervals, and radial blades 19 integral with the coupling 10 between adjacent blades 18 protrude. is the buffer elastic body 20
is filled in a compressed state. 1 feather 19
A pair of elastic bodies 20 sandwiching the two adjacent elastic bodies 20
The blades 18, 18 are continuous at a portion 20a, and the elastic body portion 20a is elastically held between the blade 19 and the boss disk portion 7.

The coupling ring 10 is made of aluminum, for example, and has an internal spline 22 (FC material, 4
5c material etc.) is cast, and this spline 2
A ring gear 23 is spline fitted to the ring gear 2 . The ring gear 23 has a ball bearing 24,
It is supported by a cover 26 via a seal 25, and the cover 26 is fitted in an elongated case 27 extending in the front-rear direction of the motorcycle in a bolt-on manner and fixed by a plurality of bolts 28. The case 27 is supported on the rear axle 1 via a boss portion 32 and supports a drive shaft 30 via a bearing 29. Bevel gear 31 on shaft 30
meshes with the corresponding bevel gear of the ring gear 23.

The rotational force of the engine is transmitted from the bevel gear 31 on the drive shaft 30 to the ring gear 23,
The rotational force is transmitted from the ring gear 23 to the internal spline 22 of the coupling ring 10 which is the input end member on the rear wheel 3 side, and the rotational force introduced into the coupling part 10 is transmitted from the blade 19 of the coupling ring 10 to the shock absorbing elastic body 20 to the boss 4. This is transmitted to the blades 18, causing the rear wheel 3 to rotate.

However, according to the conventional structure shown in FIG. 1, the coupling 10 fits into the outer circumferential surface 9 of the boss cylindrical portion 5 at the inner circumferential surface 12 to ensure assembly accuracy (concentricity). Therefore, extra machining is required to provide the outer circumferential surface 9 and inner circumferential surface 12 for centering, and the distance R ₁ from the rotation center of the fitting part (outer circumferential surface 9, inner circumferential surface 12) is Because it is short, it is difficult to obtain sufficient concentricity considering the accuracy of machining. Further, when turning the outer circumferential surface 9, the edges of the blades 18 must be separated from the outer circumferential surface 9 as shown in FIG. 1 so that a tool can enter. When viewed in the circumferential direction (Fig. 1), the overlapping area of the blades 18 and 19 decreases, and the volume of the elastic body 20 sandwiched between the blades 18 and 19 decreases, so the damper capacity becomes small considering the space. . Since the structure is complicated, the cost tends to increase.

The present invention attempts to solve the above-mentioned conventional problem caused by the small distance R ₁ from the center of rotation of the fitting part of the rear wheel boss and the coupling. The coupling is fitted to hold the coupling concentrically with respect to the boss of the rear wheel, and an embodiment is shown in FIG.

In FIG. 2, the shape and dimensions (especially radius R ₂ ) of the inner peripheral surface 15 of the boss cylindrical portion 6 are made the same as those in FIG. 1, but the outer peripheral surface 14' of the coupling 10 is
is made with a slightly larger diameter than the one in Figure 1,
The outer circumferential surface 14' is closely fitted to the inner circumferential surface 15 with a slight gap _k3 therebetween. The degree of fit in the gap _k3 is determined to be close to press-fitting, and the coupling ring 10 can be rotated while maintaining a high degree of concentricity with respect to the boss 4. The radially inner edge of the blade 18' is integrally connected to the outer periphery of the right half of the cylindrical part 5 on the disk part 7 side, and the blade 18' only needs to avoid the internal spline 22 part. The width L is approximately the same over the entire length in the radial direction, and only the portion near the cylindrical portion 5 has a slightly narrower width _L2 . Therefore, the buffer elastic body 20 has a wide portion 20 in addition to a narrow portion 20a as a portion connecting both sides of the blade 19.
b is formed, and the overlapping area of the blades 18' and 19 is increased, so the damper capacity is increased in the same space as before. That is, the volume of the elastic body 20 sandwiched between the blades 18' and 19 increases, and the volume of the elastic body connecting the elastic body parts on both sides of the blade 19 also increases, so that the elastic body 20 absorbs more torsional torque. Can be done. Since the fitting part between the boss 4 and the coupling ring 10 is located at the gap _k3 , the structure is simplified even though the space is the same as before.
Manufacturing costs are also reduced. The width of the blade 18' can be made wide over the entire length in the radial direction, and no machining is required at the connection part with the cylindrical body 5, so it can be left as cast, and no extra machining is required. becomes. Since the distance R ₂ from the rotation center of the fitting part K ₃ is sufficiently larger than the conventional distance R ₁ , the inner peripheral surface 1
5. A trowel can be created that increases the assembly accuracy (concentricity) of the coupling ring 10 in relation to the machining accuracy of the outer peripheral surface 14',
This has the advantage of improving the engagement at the spline 22, increasing power transmission efficiency, and reducing noise.

In addition, when embodying the present invention, the coupling ring and the rear wheel boss can be rigidly connected with bolts without using a buffering elastic body. In that case, the outer circumferential surface of the coupling ring can be press-fitted into the inner circumferential surface of the rear end boss, and concentricity is further improved.

[Brief explanation of the drawing]

FIG. 1 is a partial horizontal sectional view showing a conventional structure, and FIG. 2 is a drawing corresponding to FIG. 1 when the present invention is applied. 3... Rear wheel, 4... Boss, 10... Coupling, 14'... Coupling outer circumferential surface, 15... Boss inner circumferential surface, 22... Internal spline, 23... Ring gear, 30... Drive shaft.

Claims (1)

[Scope of utility model registration request] In a ring gear that receives rotational force from the drive shaft and is spline-fitted to the internal spline of the rear wheel side coupling, the outer circumferential surface of the coupling is closely fitted to the inner circumferential surface of the rear wheel boss, and the coupling is connected to the rear wheel boss. A rear wheel drive device for a motorcycle, characterized in that the rear wheel drive device is held concentrically with respect to the rear wheel drive device.