JPS62194986A - Rear fork for motorcycle - 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 [Field of Industrial Application] The present invention relates to a rear fork for a two-wheeled motor vehicle, and more particularly to one that employs a monocoque structure to achieve weight reduction.

[Prior Art] A rear fork that supports a rear wheel of a two-wheeled motor vehicle is swingably attached to a lower rear portion of a vehicle body frame using a pivot bearing. Furthermore, one end of the rear cushion unit is also attached to the rear fork. Therefore, the rear fork is a member that is required to have high rigidity. at the same time,
It is also a component that must be lightweight to avoid increasing the overall vehicle weight and unsprung load. Conventional rear forks are generally made of metal and consist of a pair of swing arms and a cross member that connects them.72 rear forks have a pair of swing arms and a cross member that are connected by welding. There is. There are also those made of plastic reinforced with fibers such as carbon fiber (hereinafter referred to as FRP). This is made of FRP around the core made of plastic.
It is made by wrapping and curing.

Further, a mudguard separate from the rear fork is usually fixed to the rear fork or the vehicle body frame. An example of this is the one described in Japanese Utility Model Application Publication No. 53-100670.

[Problems to be Solved by the Invention] Incidentally, in the case of a metal rear camera, it is not possible to reduce the thickness of component parts such as the swing arm very much because of the need for welding strength. Therefore, it becomes heavier. When the weight of the rear hood increases, the unsprung weight increases, which increases the overall weight of the vehicle and worsens fuel efficiency. Therefore, it is necessary to reduce the weight of other parts by the amount of weight increase of the rear fork.

However, since each part of the car body is always at its design limit, further weight reduction would be extremely difficult in terms of car body design. In this respect, those made of FRP can achieve a certain degree of weight reduction.

However, since the difference is only that the constituent materials have been changed and the structure is not significantly different from the metal one, the rear fork as a whole still has a considerable weight. Further, when a separate mudguard is provided, this mudguard is not a rigid member and does not contribute to improving the strength of the rear fork, but on the other hand, the mudguard itself adds weight and requires more man-hours to install.

Therefore, the present invention aims to make the rear fork as thin as possible while maintaining a certain strength by integrating the pair of swing arms with the mudguard to form a monocoque, thereby achieving weight reduction and high rigidity. Furthermore, the present invention aims to provide a rear fork which can reduce the number of parts and reduce the number of installation steps by integrating at least a portion of the mudguard.

[Means for Solving the Problems] The motorcycle rear suspension according to the present invention has the following configuration. That is, a pair of swing arms having a pivot bearing at one end and an axle bearing section for supporting the rear wheel axle at the other end, and a rigid bridge section that integrally bridges and connects the pair of swing arms. The bridge portion is provided within a range of at least the pivot bearing and the axle bearing portion, and
At least a portion of the bridge portion may form a mudguard that partially covers the rear wheel.

[Operation of the invention] A bridge portion integrally connects the pair of swing arms. Furthermore, the bridge portion is formed between the pivot bearing and the axle bearing portion and has rigidity. Therefore, the rear fork has a monocoque structure including the swing arm and the bridge portion, and has high rigidity, and the load applied to the swing arm portion is distributed over the entire bridge portion. Therefore, the area where the load can be distributed becomes large, and the entire rear fork, especially each swing arm, can be made as thin as possible. Furthermore, at least a portion of the bridge partially covers the rear wheel and acts more or less as a mudguard.

[Example] An example will be described based on FIGS. 1 to 3. FIG. 1 shows a side view of a two-wheeled motor vehicle to which an embodiment of the present invention is applied. At the lower part of the down tube F, which is a part of the body frame of this two-wheeled motor vehicle, a rear foot 1 is swingably supported by a pivot bearing 2 provided at one end thereof. The rear fork l has a monocoque structure in which the swing arm 3 and the temple 99 portion 7 are integrally formed. The swing arm 3 extends toward the rear of the vehicle body, and an axle shaft A of a rear wheel Wr is supported at an axle bearing portion 5 provided at a rear end portion of the swing arm 3. The axle bearing portion 5 is formed with an elongated portion for adjusting and supporting the axle A. The bridge portion 7 is a rigid member formed between the pivot bearing 2 and the axle bearing portion 5, that is, within a range approximately equal to the length of the swing arm 3. The bridge portion 7 also includes a mudguard portion 8 that covers a portion of the rear wheel Wr, and a rear cushion attachment portion 19 near the pivot bearing 2 to which one end of a rear cushion unit (not shown) is attached.

The detailed structure of the rear fork 1 is shown in FIG. Front end of rear fork 1 (the left side in Figure 2 is the front; the same applies hereinafter)
A pivot bearing 2 is integrally formed in the pivot bearing 2, and the ends of a pair of swing arms 3 and 4 are integrally formed at both axial ends of the pivot bearing 2. The swing arms 3 and 4 are members having an appropriate shape such as a square pipe or an inverted U-shaped cross section, and are designed to support the rear wheel Wr.
They extend approximately parallel to the rear of the vehicle at intervals slightly wider than the width of the vehicle. Swing arm 4 is provided symmetrically to swing arm 3. At the rear end of the swing arm 3.4 integral or separate axle bearings 5 and 6 are mounted. Further, a bridge portion 7 is continuously and integrally connected between the swing arms 3 and 4. The bridge portion 7 is made of the same material as the swing arm 3.4 and is a rigid member that contributes to high rigidity of the rear fork 1. The rear wheel is the rear wheel Wr.
It has an arch shape so as to cover part of the area, and the mudguard also serves as part 8. That is, an upper wall 9 is formed corresponding to the circumferential direction of the rear wheel Wr, and this upper wall 9 prevents mud from scattering in the circumferential direction of the rear wheel Wr. Further, a large number of ribs 11, 12, 13 are formed on the upper wall 9, and the bridge portion 7
This increases the rigidity of the A side wall 14 is formed on the side surface of the mudguard portion 8, and a side wall 14 is formed in a portion corresponding to the side portion of the rear wheel Wr.
The swing arms 3 and 4 are connected to each other. However, in order to reduce weight, the holes 15 and 16 are cut out at appropriate places. A rib 17 is also formed around the lightening hole 15 to increase the rigidity of the side wall 14. In addition, the bridge part 7
An arch-shaped rib 18 is also formed at the rear end edge. In addition, a lightening hole 25 is formed in the upper portion of the upper wall 9, contributing to weight reduction. In addition, drain holes 26 and 27 are opened in the corners of the upper wall 9 near the ribs 11, so that water accumulated in these areas can be drained.

The upper wall 9 has such a lightening hole 25 and a water drain hole 26.27.
Even if it has a mudguard, at least a part of it covers a part of the rear wheel Wr, so the mudguard effect is exhibited regardless of the extent of the mudguard. However, it is natural that the mudguard can be more effective without forming these openings.

Various cross-sectional shapes of these ribs are possible.

Examples are shown in FIGS. 3a, b, c, etc. Figure 3 a is A in Figure 2.
-A cross section, Figure 3 is the same C-C cross section, Figure 3 C is the same C-
C section is shown. However, other shapes than these, such as H-shape, 1-shape, 5-shape, etc., are of course possible, and are selected and used depending on the required strength of the part to be used.

The explanation will be given by returning to FIG. 2 again. A rear cushion mounting portion 19 is formed near the pivot bearing 2 of the bridge portion 7 and is continuous with the mudguard portion 8. However, since this part requires particularly high rigidity, a pair of large ribs 20 and 21 are provided. Further, mounting holes 22 and 23 for rear cushion links are opened on the side surface thereof. Further, between the ribs 20 and 21, a rear cushion opening 24 is formed to accommodate the end portion of the rear cushion.

The fork 1 having a monocoque structure can be manufactured using an appropriate plastic material such as metal or FRP. In this embodiment, the entire body is integrally molded with FRP in a mold. Therefore, while the conventional method of wrapping FRP has the problem of increased manufacturing man-hours, this embodiment can greatly reduce the manufacturing man-hours. Moreover, in the case of metal, it can be formed by press molding, casting, etc.

Furthermore, due to the monocoque structure, the bridge portion 7 also has considerable rigidity, so the swing arm 3
．． The fourth grade is made as thin and lightweight as possible compared to ordinary FRP ones. In this case, it is natural that ribs at various locations are effective in maintaining strength.

When this rear fork 1 is used, the load from the rear wheel Wr is first applied to the swing arm 3.4 from the axle bearing portion 5.6. Then, the bridge portion 7, which is a rigid member integrated with the swing arm 3.4, shares this load with the swing arm 3.4, and disperses and absorbs it over the entire bridge portion. At this time, the bridge portion 7 has a relatively large area that allows the load to be easily dispersed and absorbed by the arch-shaped mudguard portion 8 and the like. Therefore, even if the swing arm 3.4 is relatively thin and lightweight, it maintains sufficient rigidity. Also, even if the load from the rear cushion is applied to the rear cushion mounting portion 19, the same effect will occur.

This is dispersed and absorbed throughout the ridge portion 7 and swing arm 3.4. Further, since the bridge portion 7 is formed between the pivot bearing 2 and the left and right axle bearing portions 5.6, that is, within the range shown in FIG. It can contribute as a rigid member that provides rigidity.

Note that the present invention is not limited to the above embodiments, and can be applied in various ways. For example, component parts such as the swing arm and the bridge portion may be separately molded and prepared in advance, and these component parts may be integrated by gluing or the like to form a monocoque structure. Furthermore, it is of course possible to form the respective component parts from mutually different materials and to combine and integrate them.

Further, it is optional that the rear part of the bridge part extends toward the rear of the vehicle body from the position on the axle A of the rear wheel, and can also be used as a cover such as a fender.

[Effects of the Invention] The present invention has a monocoque structure by connecting and integrating a pair of swing arm bridge parts,
In addition, since the rear fork near the rear wheel at the bridge can also be used as a mudguard, there is a large area that can disperse and absorb the load applied from the rear wheel and cushion, and the swing arm etc. can be made thinner to that extent. , weight can be reduced.

Therefore, the weight of the entire rear fork can be reduced, the unsprung load can be reduced, and the vehicle body can be easily designed. This contributes to a substantial reduction in the overall weight of the vehicle, and can also improve fuel efficiency. Moreover, since at least a portion of the bridge portion partially covers the rear wheel, mud removal can be more or less effective. Since the separate mudguard that was previously required can be eliminated, it can contribute to further weight reduction, as well as a reduction in the number of parts and installation man-hours.

[Brief explanation of drawings]

1 to 3 show embodiments of the present invention. FIG. 1 is a side view of a two-wheeled motor vehicle to which the present invention is applied, FIG. 2 is a perspective view,
3A shows a cross section along line AA in FIG. 2, FIG. 3 shows a cross section along line CC in FIG. 2, and FIG. 3C shows a cross section along line CC in FIG. (Explanation of symbols) 1... Rear mount, 2... Pivot bearing, 3.4
... Swing arm, 5.6... Axle bearing part, 7.
・Tsuto ridge part, 8...Mud removal part.

Claims (1)

[Claims] a pair of swing arms having a pivot bearing at one end and an axle bearing portion for supporting a rear wheel axle at the other end;
It has a monocoque structure consisting of a rigid bridge portion that integrally bridges the pair of swing arms, and the bridge portion is provided within a range of at least the pivot bearing and the axle bearing portion, and the bridge portion is provided within a range of at least the pivot bearing and the axle bearing portion, and A rear fork for a two-wheeled motor vehicle, wherein at least a portion of the rear fork forms a mudguard that partially covers the rear wheel.