JPH0784190B2 - Frame structure in vehicles such as motorcycles - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a vehicle such as a motorcycle in which one hydraulic shock absorber is arranged immediately after a pivotal support portion of a rear arm, and more particularly to a frame for receiving the hydraulic shock absorber. Concerning the structure of.

[Prior art]

For example, in recent motorcycles, Japanese Patent Laid-Open No. 57-6098
As can be seen in Japanese Patent Publication No. 4, a hydraulic shock absorber that receives the swinging stroke of the rear arm is vertically arranged right after the pivotal support of the rear arm, and the center of gravity of the entire vehicle is located near the center of the vehicle body. By bringing them closer to each other, the mass is concentrated and the maneuverability and stability are improved.

By the way, the upper end of the hydraulic shock absorber is connected to the frame side.However, due to the structure of this frame, when the upper end of the hydraulic shock absorber is located between the left and right main pipes extending rearward from the steering head pipe, A cross member is spanned between these main pipes, and the upper end of the hydraulic shock absorber is connected to this cross member.

[Problems to be solved by the invention]

In the case of this configuration, the impact due to the compression or extension of the hydraulic shock absorber is concentrated and applied to the connecting portion of the main pipe with the cross member. However, since the main pipe is thinned for weight reduction, this main pipe is In order to bear a local load on the, it is necessary to significantly reinforce the connecting portion with the cross member. Therefore, the number of parts and the time and effort required for welding increase correspondingly, leading to high cost and weight, and the frame structure becomes complicated.

The present invention has been made in view of the above circumstances, and it is possible to locally form a support portion that receives a cross member with a thick wall, and a bracket including the support portion can securely receive an impact from a hydraulic shock absorber. It is an object of the present invention to provide a frame structure for a vehicle such as a motorcycle, which can prevent the hydraulic shock absorber from significantly protruding below the rear arm while ensuring the length of the hydraulic shock absorber.

[Means for solving problems]

To achieve the above object, the present invention is a pair of left and right main pipes extending obliquely downward and rearward from the steering head pipe toward the front end portion of the rear arm in a substantially straight line shape in a side view, and connected to the rear end portions of these main pipes. A frame having a pair of left and right brackets made of a forged product or a forged product, and an engine having a crankcase that is supported by the frame and that is located near the rear portion of the main pipe and the bracket. The front end of the rear arm is pivotally supported between the brackets, and a hydraulic shock absorber that receives the swing stroke of the rear arm is vertically arranged immediately after the pivotal support of the rear arm. It is premised on a vehicle such as a motorcycle in which the upper end portion of this hydraulic shock absorber is connected to the frame side.

Then, a support portion extending upward to a position higher than the crankcase of the engine is integrally formed on the upper end portion of each bracket, and a cross member is hung between the upper end portions of these support portions, and the cross member is It is characterized in that the upper end of the hydraulic shock absorber is connected to the member.

[Action]

According to this configuration, the bracket is forged or cast-molded, so that it becomes easy to locally configure the support portion that receives the cross member to be thick. Therefore, the local load applied through the cross member is carried by the high-rigidity support portion as much as the wall thickness is increased, so that the load is distributed and transmitted to the thin main pipe. The load burden of is reduced and no special reinforcement is required.

Further, since the support portion projects upward, the cross member that receives the upper end portion of the hydraulic shock absorber can be pulled up to a position higher than the crankcase. Therefore, while the main pipe extends obliquely rearward and downward, and the bracket is located at the lower portion of the frame, the connection position of the upper end of the hydraulic shock absorber with respect to the frame can be raised, and the hydraulic shock absorber's corresponding position can be increased. The total length can be lengthened. At the same time, since the mounting position of the hydraulic shock absorber with respect to the frame is shifted upward, the amount of downward projection of the rear arm of the hydraulic shock absorber can be suppressed to a small amount even though the total length of the hydraulic shock absorber is increased.

Example of Invention

An embodiment of the present invention will be described below with reference to the drawings applied to a motorcycle.

In the figure, 1 is a frame made of aluminum alloy, and a front fork 3 is pivotally supported on a steering head pipe 2 which is vertically installed at the front end thereof. The steering head pipe 2 is welded with a pair of left and right main pipes 4 extending obliquely rearward and downward in a substantially straight line in a side view. The main pipes 4, 4 of the present embodiment are a pair of thin-walled sheet metal members formed in a substantially U-shaped cross-section, abutted and welded from the vehicle width direction, and the cross-sectional shape becomes vertically long in the vertical direction. It is formed in a flat rectangular tube shape. And these main pipes 4,4
In the front end portion connected to the steering head pipe 2, the longitudinal dimension thereof is formed to be substantially equal to the axial length of the head pipe 2 in order to enhance the coupling strength and rigidity. Moreover,
The vertical dimension of the main pipes 4, 4 is gradually reduced as it goes rearward, and therefore the side shape of the main pipes 4, 4 is tapered as it goes backward. Also,
Immediately after the steering head pipe 2, the main pipes 4, 4 are expanded outward in the vehicle width direction and extend rearward in parallel with each other. Flat plate brackets 5, 5 are welded to the rear ends of the main pipes 4, 4. Has been done. The brackets 5, 5 are, for example, cast and molded from an aluminum alloy.
A down tube 7 is installed between the lower front end of the main pipe 4 and a cross pipe 6 connecting the front ends of the main pipes 4, 4.

Further, as shown in FIG. 3, an engine 8 is mounted between the main pipes 4, 4 and the down tube 7.
The engine 8 has a crankcase 8a and a cylinder 8b connected to the front upper surface of the crankcase 8a. The crankcase 8a is located below the main pipes 4, 4, and the rear portion of the crankcase 8a is adjacent to the rear lower surface of the main pipes 4, 4 and the front surfaces of the brackets 5, 5. The upper surface of the crankcase 8a is located at substantially the same height as the upper ends of the brackets 5,5.

By the way, the brackets 5 and 5 are connected to each other at two locations, an upper end portion and a lower end portion thereof, through cross tubes 9a and 9b, respectively, and a front end portion of a rear arm 10 is provided between the brackets 5 and 5 by a pivot shaft 11. It is pivotally supported via. The rear arm 10 has left and right arm portions 12 and 12 extending rearward and substantially parallel to each other, and a rear wheel 13 is pivotally supported between rear end portions of the arm portions 12 and 12. Then, between the front end portions of the arm portions 12 and 12 and immediately after the pivot shaft 11, one hydraulic shock absorber 14 is vertically inserted and arranged along the vertical direction. Is located near the center of the vehicle body. A lower end portion 14a of the hydraulic shock absorber 14 is connected to the rear arm 10 via a link mechanism 15. The link mechanism 15 is configured so that the relay arm 17 pivotally supported by the cross tube 9b via the bracket 16 and the tip end portions of the left and right relay arms 19, 19 pivotally supported on the lower surface of the front end portion of the rear arm 10 are rotatable. The lower ends 14a of the hydraulic shock absorbers 14 are connected to the connecting portions of these arms 17, 19, 19. Also,
The hydraulic shock absorber 14 is slightly tilted forward, and its upper end portion 14b is connected to the frame 1 side. Ie bracket
Support portions 20, 20 extending upward are integrally cast-molded on the upper rear surfaces of the 5, 5. As shown in FIG. 3, the upper ends of the supporting portions 20 and 20 are raised to a position higher than the upper surface of the crankcase 8a, and these supporting portions 20 and 20 are formed to be thicker than the main pipes 4 and 4. Has been done. A pipe-shaped cross member 21 is spanned between the upper ends of the support parts 20, 20, and in the case of the present embodiment, both ends of the cross member 21 are recessed parts 22, 22 provided in the support parts 20, 20. It is fixed by fitting it inside and welding it. A bracket 24 having left and right wall portions 23, 23 extending downward is welded to the lower surface of the middle portion of the cross member 21.
The upper end 14b of the hydraulic shock absorber 14 is interposed between the bolt 2 and
5 and pivoted via nut 26. Therefore, in the case of the present embodiment, the upper end pivot portion of the hydraulic shock absorber 14 is located immediately below the cross member 21.

Incidentally, the support portion 20, 20, facing the head 25a of the bolt 25 and the nut 26, respectively, through holes 28, 28 for inserting a tool when rotating the bolt 25 or the nut 26. It has been opened.

According to such a configuration, since the support portions 20, 20 for receiving the cross member 21 are integrally cast-molded on the brackets 5, 5 connected to the main pipes 4, 4, the support portions 20, 20 are locally formed by meat. It becomes easy to form a thick structure, and sufficient rigidity and strength can be secured. Therefore, the local load applied through the cross member 21 due to the compression or extension of the hydraulic shock absorber 14 is carried by the thick support portions 20 and 20, so that the thin men-in pipe is used.
The load from the hydraulic shock absorber 14 is transmitted to the 4, 4 in a state in which the load is largely dispersed, and the load burden on the main pipes 4, 4 is reduced accordingly. Therefore, no special reinforcement is required, the number of parts and welding points are small, and the frame structure can be simplified and the weight can be reduced.

Moreover, according to the above configuration, the support portions 20,
20 is projected upward, and its tip reaches a position higher than the upper surface of the crankcase 8a of the engine 8,
The cross member 21 that receives the upper end portion 14b of the hydraulic shock absorber 14 can be pulled up to a position higher than the brackets 5, 5. Therefore, although the brackets 5 and 5 are located in the lower portion of the frame 1 by the amount of the main pipes 4 and 4 extending obliquely rearward and downward, the upper end portion 14b of the hydraulic shock absorber 14 with respect to the frame 1 is The connecting position can be raised.

Therefore, the total length of the hydraulic shock absorber 14 can be increased, and the swing stroke of the rear arm 10 can be sufficiently secured.

Moreover, since the mounting position of the hydraulic shock absorber 14 with respect to the frame 1 can be shifted upward, the hydraulic shock absorber 14 largely projects below the rear arm 10 in spite of making the total length of the hydraulic shock absorber 14 long. Can be prevented. Therefore, there is an advantage that the lower end portion 14a of the hydraulic shock absorber 14 and the link mechanism 15 are less likely to interfere with the road surface.

Further, in the case of the present embodiment, since the upper end pivotal support portion of the hydraulic shock absorber 14 is located immediately below the cross member 21, it is difficult for torsion or bending force to be generated in the cross member 21 and the bracket 24, which is advantageous in strength.

The vehicle according to the present invention is not limited to a motorcycle, and may be, for example, a motorcycle having two rear wheels, and the bracket is not limited to a cast molded product and may be a forged molded product.

〔The invention's effect〕

According to the present invention described in detail above, the wall thickness of the support portion can be locally increased, and the rigidity and strength of the support portion can be sufficiently ensured. Therefore, when the rear arm strokes up and down, the load transmitted from the hydraulic shock absorber to the cross member is mainly carried by the support portion and the bracket, and the load burden on the main pipe is reduced accordingly. Therefore, it is not necessary to reinforce the main pipe, and the frame structure can be simplified and the weight can be reduced.

Moreover, the cross member that receives the upper end of the hydraulic shock absorber,
Since the bracket can be pulled up to a position higher than the bracket, the bracket is located at the bottom of the frame by the amount that the main pipe extends obliquely downward and rearward, but the upper end of the hydraulic shock absorber is connected to this frame. The position is higher. Therefore, the total length of the hydraulic shock absorber can be increased, and the swing stroke of the rear arm can be sufficiently secured.

Further, since the mounting position of the hydraulic shock absorber with respect to the frame is shifted upward, it is possible to prevent the hydraulic shock absorber from projecting largely below the rear arm even though the total length of the hydraulic shock absorber is increased, and the lower end of the hydraulic shock absorber is prevented. There is an advantage that the part is less likely to interfere with the road surface.

[Brief description of drawings]

The drawings show one embodiment of the present invention. Fig. 1 is a side view around a bracket, Fig. 2 is a view seen from the direction of the line II in Fig. 1, and Fig. 3 is a side view of a motorcycle. . 1 ... Frame, 2 ... Steering head pipe, 4 ... Main pipe, 5 ... Bracket, 8 ... Engine, 8a ... Crankcase, 10 ... Rear arm, 14 ... Hydraulic shock absorber, 14b ... Upper end Section, 20 …… Support section, 21 …… Cross member.

Claims (1)

[Claims] 1. A pair of left and right main pipes extending obliquely downward and rearward from the steering head pipe toward the front end of the rear arm so as to be substantially linear in a side view, and a forged or forged product connected to the rear ends of the main pipes. A frame having a pair of left and right brackets consisting of, and an engine having a crankcase that is supported by the frame and that is located near the rear portion of the main pipe and the bracket, and between the brackets, The front end of the rear arm is swingably supported, and a hydraulic shock absorber that receives the swing stroke of the rear arm is vertically arranged immediately after the pivotal support of the rear arm. In a vehicle such as a motorcycle in which the upper end of each bracket is connected to the frame side, the upper end of each bracket is Support parts that extend upward toward a position higher than the crankcase of the engine are integrally molded, and a cross member is hung between the upper ends of these support parts, and the upper end part of the hydraulic shock absorber is connected to this cross member. A frame structure in a vehicle such as a motorcycle characterized by the above.