JPH02254088A - Motor bicycle - Google Patents

Abstract

PURPOSE:To improve a balance between weights on both sides by a method wherein, in a device in which the one of the arm members of rear arm is bent in a manner to prevent the occurrence of interference with an exhaust pipe, a butter is situated eccentrically toward the arm member opposite to the arm member bent toward a center in the direction of the width of a bicycle. CONSTITUTION:A rear arm 10 formed with a pair of arm members 10a and 10b on both sides is vertically rockably supported to a rear arm bracket 6 with which a part of a car body frame is formed, and a rear wheel 4 is supported to the rear end of the rear arm 10. The arm member 10a, on the side where an exhaust pipe 13 is arranged, of a pair of the arm members 10a and 10b has an intermediate part formed in a shape in which it is bent upwardly in the shape of a chevron, and is prevented from interference with the exhaust pipe 13. The rear arm 10 is resiliently supported to a single buffer 12 through a link mechanism. In a so formed motor bicycle, the buffer 12 is arranged eccentrically from a central line CL in the direction of the width of a bicycle by a distance (e) on the opposite side to the arm member 10a, bent in the shape of a chevron, and a balance between weights on both sides is ensured.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention provides an arrangement in which one arm member of a rear arm is bent so as not to interfere with the exhaust pipe, in order to improve running stability without increasing weight. Regarding motorcycles.

[Prior Art] Engine performance largely depends on the exhaust resistance of the exhaust pipe. For this reason, in order to reduce the exhaust resistance of the exhaust pipe of a motorcycle, the shape of the exhaust pipe is sometimes designed to be as straight as possible. For example, in one such design, when the exhaust pipe crosses one arm member of the rear arm, the exhaust pipe side is kept straight, and the arm member side is bent into a chevron shape. Some proposals have been made to prevent the exhaust pipe from interfering with the exhaust pipe.

On the other hand, as a shock absorber for supporting the intermediate portion of the rear arm, there is one in which only one shock absorber is provided at the center of the width of the vehicle body. However, when combining a rear arm with a bent arm member to one such shock absorber, the bending arm member has weaker bending rigidity than the other arm member, so its Unless the wall thickness is increased or the cross-sectional shape is increased, it will not be possible to balance the strength between the left and right sides. However, if such measures are taken, not only will the overall weight increase, but the difference in weight balance will increase from side to side, resulting in a decrease in running stability.

[Problem to be solved by the invention]

An object of the present invention is to support a rear arm having an arm member bent so as not to interfere with the exhaust pipe with a single shock absorber at the center in the width direction of the vehicle body, without causing an increase in weight. To provide a two-wheeled motor vehicle which enables left and right weight balance and improves running stability.

[Means to solve the problem]

To achieve the above object, the present invention pivots a rear arm consisting of a pair of left and right arm members at the rear of a vehicle body frame, and supports the intermediate portion of the post-cough arm with a single shock absorber at the center in the width direction of the vehicle body. and in a motorcycle in which one of the pair of arm members is bent so as not to interfere with the exhaust pipe, the shock absorber is placed on the opposite side of the bent arm member with respect to the widthwise center of the vehicle body. It is characterized by being eccentrically arranged toward the arm member.

By making the central shock absorber eccentric to the arm member on the opposite side of the bending arm member with respect to the center in the width direction of the vehicle body, the shared load applied to the bending arm member side, which has lower rigidity, can be reduced. , it is possible to ensure the right and left weight balance without increasing the wall thickness or cross-sectional shape of the bending arm member. Therefore, this does not increase weight and improves running stability.

〔Example〕

The figure shows a motorcycle according to an embodiment of the present invention, where ■ is a body frame, 2 is an engine, 3 is a front wheel, and 4 is a rear wheel. The main part of the vehicle body frame 1 is configured such that a tank frame 7 and a down tube 8 connect a head vibe 5 and a rear arm bracket 6 arranged in the front and rear.

In this embodiment, as shown in FIGS. 1 and 3, a pair of left and right down tubes 8 are provided, and when viewed from the side, the middle portion thereof is bent downward in a "he" shape, and its front end is connected to the head vibe 5. In addition, the rear end sides are welded to a pair of left and right rear arm brackets 6.6. Further, the tank frame 7 is wide and substantially linear in side view, and is formed so as to straddle the pair of left and right down tubes 8, 8 in plan view. It also forms a tank space for storing fuel inside. The tank frame 7 having such a shape is connected to the head vibe 5 at the front end and to the rear arm bracket 6 at the rear end with bolts, and furthermore, the middle part on the lower side is connected to the down tube 8 at two places, front and rear. They are connected with bolts (see Figure 6). In this manner, the vehicle body frame I exhibits extremely high rigidity because the two bent sides of the downchie 8 and the straight tank frame 7 form a triangle when viewed from the side.

Further, a case 24 is provided in a space above the tank frame 7 where a fuel tank would be provided in a conventional vehicle. In this case 24, for example, electrical equipment or a helmet can be stored.

A pair of front forks 9, 9 are supported on the head vibrator 5 of the vehicle body frame 1 so as to be rotatable left and right about the axis of the head vibrator 5, and the front wheel 3 is supported at the lower end thereof. A footrest 25 is fixed to the rear arm bracket 6.

Further, a rear arm 10 consisting of a pair of left and right arm members 10a and 10b is pivotally supported on the rear arm bracket 6 so as to be able to swing up and down with a bolt 16 (see FIG. 4).
. Thereafter, the rear wheel 4 is supported at the rear end of the arm 10.

Further, after this, the arm lO connects its intermediate portion to the link mechanism 1.
1 and is elastically supported by one shock absorber 12.

Further, among the pair of arm members 10a and 10b, the arm member 10a located on the side where the exhaust pipe 13 is arranged intersects with the exhaust pipe 13 in a plan view. However, this arm member 10a is
The middle part is bent upward into a chevron shape so as not to interfere with the That is, when the exhaust pipe 13 is bent, the exhaust resistance increases due to the bending, so the exhaust resistance of the exhaust pipe 13 is reduced by bending the arm member 10a to a large extent.

As shown in FIG. 3, the shock absorber I2 has an arm bent in the shape of a chevron with respect to the widthwise center line CL of the vehicle body (a line segment connecting the widthwise center of the front wheel 3 and the widthwise center of the rear wheel 40). It is arranged eccentrically by a distance Me on the opposite side from the member 10a. Further, like the shock absorber 12, the link mechanism 11 is also disposed eccentrically by a distance e on the opposite side of the curved arm member 10a, and is pivotally supported by the rear arm bracket 6 and the rear arm 10. As described above, the pair of arm members 10a
, 10b is formed into an extremely bent shape compared to the other, the bent arm member 10a has a lower rigidity than the other arm member 10b.

In order to equalize such a difference in rigidity, the wall thickness or cross-sectional shape of the bent arm member 10a must be increased. However, by making the position of the shock absorber 12 eccentric with respect to the center line CL as described above, it is possible to change the shared load on both arm members 10a and 1ob, and the bent arm member 10a can be made thicker. It is possible to balance the weight with the other arm member without changing the weight. Therefore, this does not result in an increase in overall weight, and the running stability can also be improved.

The engine 2 in this embodiment is a one-cylinder, two-stroke engine. In addition, in a side view, the cylinder portion 2c and the transmission case portion 2m are bent upwardly in a generally “H” shape convex around the vicinity of the crankshaft 14. Further, the engine 2 has a center of gravity near the crankshaft 14 and is suspended from the down tube 8 by bolts 15 above the center of gravity. Further, the rear end of the engine is fixed to the rear arm bracket 6 by a pivot bolt 16 of the rear arm 10 (see FIG. 4).

With the engine 2 suspended in this manner, the cylinder portion 2c is inclined downward, and its axis EL is located below the line connecting the crankshaft 14 and the axle 3C of the front wheel 3. ing.

Further, the position of the crankshaft 14 is higher than the horizontal position of the bolt 16 by a distance Mh.

A large space is formed on the upper side of the cylinder portion 2C that is inclined downward as described above, and a downdraft type carburetor 17 and a radiator unit 8 for engine cooling water are arranged in this space. Further, in this embodiment, the radiator 18 is provided separately into two parts, left and right (see FIG. 2), so that air can smoothly pass through the space 19 formed between the two. The carburetor 17 is arranged so as to face this space 19 when viewed from the front, and is covered with a case 20.

The case 20 is provided with an air guide hole 21 that extends rearward from the front surface, bends at a substantially right angle at the rear end, and communicates with the inside of the case. This case 20 prevents the dynamic pressure of the air supplied to the carburetor 17 due to the shape of the air guide hole 21, and also prevents the supplied air from being heated by the radiator, thereby stabilizing the performance of the carburetor 17. I try to let them do it.

Further, a cowling 22 is provided on the outside of the vehicle body so as to cover the front side and both sides of the front part. An air guide plate 23 is provided on the lower surface of the front end of the cowling 22, and this air guide plate 23 smoothly guides air entering from the front to the air guide hole 21 of the case 20.

Note that the engine mounted in the present invention is not limited to a 2-stroke engine, but may be a 4-stroke engine.

〔Effect of the invention〕

As described above, in the motorcycle of the present invention, a 4-degree rear arm made up of a pair of left and right arm members is pivotally supported at the rear of the vehicle body frame, and one rear arm is connected at the middle portion of the rear arm at the center in the width direction of the vehicle body. The motorcycle is supported by a shock absorber, and one of the pair of arm members is bent so as not to interfere with an exhaust pipe, wherein the arm member is bent with respect to the widthwise center of the vehicle body. It is arranged eccentrically toward the arm member on the opposite side.

In this way, the central shock absorber is eccentrically placed toward the arm member on the opposite side of the bending arm member with respect to the widthwise center of the vehicle body, reducing the shared load on the bending arm member side, which has lower rigidity. However, the weight balance of both the left and right arm members can be ensured without increasing the wall thickness or cross-sectional shape of the bending arm member. Therefore, there is no increase in overall weight, and running stability is also improved.

[Brief explanation of drawings]

FIG. 1 is a side view of a motorcycle according to an embodiment of the present invention;
Fig. 2 is a front view showing only the essential parts, Fig. 3 is a plan view showing only the essential parts, Fig. 4 is a sectional view of the rear arm pivot, and Fig. 5 is a cross section taken along the line A-A in Fig. 1. 6 is a sectional view taken along the line B-B in FIG. 1, and FIG. 7 is a view taken along the line C-C in FIG. 1. ■...Vehicle frame, 2...Engine, 2c...
Cylinder part, 2m...Mission case part, 3...Front wheel, 4...Rear wheel, 5...Head vibe, 6...Rear arm bracket, 7...Tank frame, 8... Down tube, 9...front fork, 10...rear arm, IQa, 10b...arm member, 12...buffer, 13...exhaust pipe. Agent Patent Attorney Nobuo Ogawa −

Claims (1)

[Claims] A rear arm consisting of a pair of left and right arm members is pivotally supported at the rear of the vehicle body frame, and an intermediate portion of the rear arm is supported by a shock absorber at a central portion in the width direction of the vehicle body. In a motorcycle in which one of the shock absorbers is bent so as not to interfere with the exhaust pipe, the shock absorber is arranged eccentrically toward an arm member on the opposite side of the bent arm member with respect to the widthwise center of the vehicle body. motorcycle.