JPS62198586A - Rear fork for motorcycle, etc. - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is applicable to a Yahoo!
In particular, the present invention relates to a structure that can be made lighter and more rigid.

[Prior Art] A rear fork of a motorcycle, etc. has a pair of swing arms that are pivotably supported at one end at the rear of the body frame of the motorcycle and extend rearward in a bifurcated shape. It has a rear end that pivotally supports the rear wheel. Also,
A cross member that connects a pair of swing arms to each other and supports a rear cushion is provided near the pivot of the rear hood. This rear fork must have high rigidity because it is subjected to bending loads and torsional loads from the rear wheels and the like. In addition, it is necessary to reduce the weight as much as possible so as not to increase the unsprung weight.

As one of such conventional examples, Japanese Patent Application Laid-Open No. 59-2958
There is one described in Publication No. 1. This is shown in FIG. This conventional rear fork is made entirely of aluminum or the like, and has a pair of swing arms a and b.
and a cross member C that joins the two. Each component is formed separately in advance, and then integrated and assembled by welding. At this time, cross member C
Both sides of the swing arms a and b are welded at the shaded portions on each side of the swing arms a and b. Also, swing arm a,
Pivot bearings d and e are fixed to the front end of b. Furthermore, a mounting hole f for a rear cushion is formed in the cross member C, and the stays g and h, which are link mounting portions, are welded in parallel to the edge of this opening. The stays g and h pivotally support the link of the rear cushion through a shaft support hole opened at the side. Note that axle holes i and j are provided at the rear ends of swing arms a and b,
Inside this, a rear wheel axle (not shown) is supported so as to be movable and adjustable in the longitudinal direction.

[Problems to be solved by the invention] By the way, in the above conventional example, swing arms a, b
When welding these to both sides of the cross member C, the welding work is very difficult and requires skill.

In other words, in order to reduce weight, it is necessary to use as thin a material as possible for welding. Moreover, the weld is a part where stress is concentrated at all times, and the strength of the weld has a large influence on the rigidity of the rear hood as a whole. Therefore, in order to achieve a predetermined welding strength under such severe restrictions, skilled techniques are required, making mass production difficult.

Furthermore, there is a limit to how thin the wall can be made due to welding strength, and it is difficult to further reduce the weight.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a rear fork that can be made as light and rigid as possible, and that has a structure suitable for mass production.

[Means for Solving the Problems] A rear fork for a motorcycle or the like according to the present invention has the following configuration. That is, a pair of swing arms made of pipe material, a cross member that joins the two swing arms at one end of the pair of swing arms, and a cross member that is provided at the other end of the pair of swing arms and that connects the axle of the rear wheel. In the rear fork, the cross member has a pivot shaft at its end on the vehicle body attachment side, and the cross member has extensions extending laterally on both sides of the cross member that joins with the swing arm. protruding parts are provided above and below in the direction in which bending rigidity is required, and a protruding joint part is provided in a part surrounded by the pivot shaft and the upper and lower extension parts, and one end part of the swing arm The swing arm is fixed between the upper and lower extension parts to form a double wall structure on the upper and lower sides, and both ends of the swing arm have a fitting structure between the joint part and the end piece, and each fitting part It is characterized by a double wall structure.

[Function of the invention] The end of the swing arm is made of pine wood, and has a double wall structure at each joint. form. This double-walled structure has two walls, top and bottom, in the direction where bending rigidity is required.
Placed on both sides of the cross member.

Further, both ends of the swing arm each form a double wall structure due to the fitting structure between the joint portion and the end piece. Therefore, both bending rigidity and torsional rigidity are extremely high. Therefore, if an excessive load is applied to the swing arm or cross member, first,
In the direction of bending loads, the double wall structure provides sufficient joint strength to provide bending rigidity to withstand this load and distribute the load across both the swing arm and cross member. Furthermore, when a torsional load is applied to the swing arm, both ends of the swing arm exhibit torsional rigidity and are unlikely to be deformed since they have a double wall structure. Therefore, the entire rear fork has increased rigidity, and each component can be made relatively thinner to that extent. Furthermore, since the conventional welding work between the swing arm side surface and the cross member side surface is not required, mass production is possible with relatively little skill required.

[Example] Examples of the present invention are shown in FIGS. 2 to 5. Figure 2 shows
FIG. 2 is a side view of a motorcycle to which the present invention is applied, and the front end of the rear fork 1 (in the following description, the side in the direction of vehicle movement is referred to as the front) is connected to the main pipe M, which is the body frame, by a pivot P. It is pivotally attached to a pipe D connected to the rear part so as to be able to swing freely. Also, the rear fork l
A rear cushion Re is attached to the front part of the vehicle via its link Lk. A rear wheel Wr is pivotally supported at the rear end of the rear fork 1.

FIG. 3 is a plan view of the rear fork l. The rear fork 1 has a pair of swing arms 2.3. A pivot bearing 4 is provided at its front end, and is connected to the rear part of the vehicle body frame (pipe D) through the pivot connection. The pivot bearing 4 is provided at the front end of a cross member 5 in which the swing arms 2 and 3 are joined and integrated.

This cross member 5 is a member to which the rear cushion Re and the link Lk are attached, and is a rigid member that can withstand the bending load and torsional load applied from the swing arm 2.3. At the rear end of the swing arm 2.3, an end piece 6.7 supporting the axle is attached by fitting.

FIG. 4 is an assembled exploded view of the rear fork 1. The swing arm 2.3 is a symmetrically formed square pipe member, and both ends thereof are cut-off to form open ends. However, the cross-sectional shape of the swing arm 2.3 may be arbitrary, such as round or irregularly shaped. These swing arms 2 and 3 are manufactured from a suitable material such as metal or plastic, but in this embodiment, they are molded from FRP, for example, a material made of carbon fiber impregnated with epoxy resin. The cross member 5 is also molded from FRP material in the same way, and the pivot bearing 4 is integrated into its front end. A pair of parallel ribs 8 are formed in the center of the cross member 5. A mounting space 9 for a rear cushion Rc is formed between the ribs 8. cross member 5
An extending portion 10 is formed on a side portion of the holder 10 to extend in a substantially horizontal direction. A joint portion 11 that integrally projects rearward from the pivot bearing 4 is formed below the extension portion 10 . The joint portion 11 has a size that allows it to fit into the open end of the swing arm 2. Furthermore, a side attachment piece 12 is formed below the extension portion 10 and at the rear of the cross member 5.

A side wall of the swing arm 2 is adhered to the side attachment piece 12 . Although not visible in the figure, portions that function similarly to the joint portion 11 and the side attachment pieces 12 are symmetrically formed on the opposite side of the cross member 5 as well.

At the bottom of the cross member 5, a plate-shaped bottom plate 13 is provided.
They are integrated by gluing or the like. This member is for making the entire cross member 5 into a box shape and increasing the rigidity. When the bottom plate 13 is integrated with the bottom of the cross member 5, its both sides extend to the sides of the bottom of the cross member 5 in correspondence with the extension 10, and the lower extension extends to the sides of the bottom of the cross member 5. Eggplant.

Further, an opening 14 corresponding to the mounting space 9 is formed in the center of the bottom plate 13, allowing movement of the rear cushion Rc and the link Lk. However, this member can also be molded integrally with the cross member 5. Note that an end piece 6 is fitted into the rear end opening of the swing arm 2. The end piece 6 has a long hole 1 that supports the axle.
5 is formed, and a fitting part 1 is further formed through a flange 16.
7 is formed. The fitting part 17 is connected to the swing arm 2
It is formed so that it can be fitted into the rear end opening of. Further, an end piece 7 is also formed on the swing arm 3, and an elongated hole 18, a flange 19, and a fitting portion 20 are similarly formed therein.

Next, a method of assembling the rear fork l from each component will be explained. Each component shown exploded in Figure 4 is as follows:
Each is formed separately.

Therefore, first, attach the front end of the swing arm 2 to the joint part 1.
1, and then the back surface of the extending portion 10 and the top surface of the swing arm 2, and furthermore, the side attachment piece 12 and the side surface of the swing arm 2 are bonded together. Do the same on the Swijig arm 3 side. Thereafter, the bottom plate 13 is bonded to the bottom of the cross member 5. At this time, the lower surface of the swing arm 2.3 and the extending portions, which are both end portions of the bottom plate 13 and extend from the bottom of the cross member 5 to both sides, are bonded. As a result, the cross member 5 and the swing arm 3 are integrated. In addition to adhesion, these integration means can be appropriately selected depending on the material, such as welding. Thereafter, the rear end pieces 6 and 7 of the swing arm 2.3 are fitted and integrated. This completes the assembly of the rear fork 1.

Figure 5 shows the cross member 5 and swing arms 2 and 3.
The state after integration is shown. The swing arm 2 has its upper and lower surfaces adhered to the extension portion 10 and the bottom plate 13, and its side surfaces are adhered to the side attachment pieces 12. Further, the swing arm 3 is bonded and integrated at the top and bottom and on the sides by the extension part 10a and the side attachment piece 12a, which are formed symmetrically with the extension part 10 and the side attachment piece 12, and the bottom plate 13. ing. The rear camera 1 constructed in this manner has the upper and lower surfaces of the swing arm 2.3 connected to the extending portions 1, respectively.
0.10a and the bottom plate 13 form a double-walled structure and are reinforced. In addition, this double wall structure has a bending rigidity in the direction that requires bending rigidity, that is, in the vertical direction of the figure.
Each swing arm is formed at three locations on the top and bottom. The front and rear ends of each swing arm have a joint portion 11,
The double-wall structure is similarly reinforced by end pieces 6, 7, etc. Therefore, it has a highly rigid structure with both high bending rigidity and torsional rigidity.

Therefore, for swing arm 2.3 and cross member 5,
When an excessive load is applied, the swing arms 2 and 3 and the cross member 5 are connected vertically by two double wall structures, so the strength of the joint is sufficiently large. Therefore, the load is distributed to both the swing arms 2 and 3 and the cross member 5. In addition, when a torsional load is applied to the swing arm 2.3, the double wall structure formed at both ends provides high torsional rigidity and does not easily deform. Therefore, the entire rear fork has become highly rigid, making it possible to make it relatively thinner to that extent, making it possible to reduce weight as much as possible. Furthermore, since the swing arms 2 and 3 and the cross member 5 can be joined between the upper and lower sides of each swing arm and the extension of the cross member 5, joining work such as gluing becomes easy and requires special skill. A predetermined bonding strength can be obtained without the need for this. This joining work is
It has good workability and is suitable for mass production.

In this example, the entire rear hood is molded from FRP, and each component consisting of the swing arm 2.3, cross member 5, and end piece 6.7 is molded separately. . Therefore, the molding surface formed by the mold surface becomes the external appearance of the product as it is, and finishing work after molding is easy.

Therefore, finishing work by polishing after molding, which was essential in the conventional method of wrapping FRP around a core and molding it, can be eliminated, reducing the number of man-hours and providing extremely good workability. However, it goes without saying that it can also be manufactured using various metal materials such as aluminum and by appropriate molding means.

Also, the joint portions 1 at both ends of the swing arm
1 and the end piece 6.7 is relative, and each member may be fitted to the outside of the end of the swing arm.

[Effects of the Invention] The rear fork of the present invention has a double wall structure formed at the joint between the swing arm and the cross member, and a double wall structure formed at both ends of the swing arm. Furthermore, the double wall structure of the swing arm and the cross member is arranged at two locations on both sides of the cross member, one above and the other in the direction in which bending rigidity is required. Therefore, both bending rigidity and torsional rigidity are extremely high, achieving high rigidity. Furthermore, each component can be made relatively thinner by that amount, and the weight can be reduced as much as possible. Furthermore, since the conventional welding work between the swing arm side surface and the cross member side surface is not required, no skill is required and mass productivity can be improved. In addition, the weight of the rear hood can be reduced, the unsprung load can be reduced, the weight of the vehicle can also be reduced, and fuel efficiency can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded view of a conventional example. 2 to 5 show examples, FIG. 2 is a side view of an application example of the present invention, and FIG. 3 is a side view of an application example of the present invention.
The figure is a plan view of the main parts, FIG. 4 is an exploded perspective view, and FIG. 5 is a sectional view taken along the line V--V in FIG. 3. (Explanation of symbols) 1... Rear hood only, 2.3... Swing arm,
4... Pivot bearing, 5... Cross member, 6.7
...End piece, 11...Joint part, 13.
・Bottom plate.

Claims (1)

[Claims] A pair of swing arms made of pipe material, a cross member that joins the two swing arms at one end of the pair, and an end piece that is provided at the other end of the pair of swing arms and pivotally supports an axle of a rear wheel. In the rear fork, the cross member has a pivot shaft at its end on the vehicle body attachment side, and the cross member has extending portions extending laterally on both sides of the cross member that joins with the swing arm. Joint parts are provided above and below in the direction in which bending rigidity is required, and protrude from a portion surrounded by the pivot shaft and the upper and lower extensions, and one end of the swing arm is connected to the upper and lower extensions. By fixing between the parts, a double wall structure is formed in the upper and lower sides, and both ends of the swing arm have a fitting structure between the joint part and the end piece, and each fitting part has a double wall structure. A rear fork for motorcycles, etc., characterized by a heavy wall structure.