JP2768942B2 - Motorcycle rear arm - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a rear arm of a motorcycle, and more particularly to improvement of rigidity of a body portion. 2. Description of the Related Art Conventionally, in a motorcycle, a rear arm is pivotally supported by a body frame so as to be vertically swingable, and a rear wheel is rotatably supported at a rear end of the rear arm. This rear arm is generally formed by connecting a front end of a pair of left and right arms supporting a rear wheel with a body portion, and forming a pivot portion at the front end of the body portion which is pivotally supported by a body frame. Have been. In such a rear arm, since a large load acts particularly on the body, it is important to improve the rigidity around the body. Therefore, conventionally, various structures that can improve the rigidity of this portion have been proposed. For example, as described in Japanese Utility Model Application Laid-Open No. 52194/1985, the left and right arms are extruded, or In some cases, the body portion is formed of an integrally cast product, and both are welded and fixed, in addition to being formed by a drawn member. [Problems to be Solved by the Invention] The conventional rear arm described in the above publication is advantageous in terms of improving rigidity because the body portion is formed of an integrally cast product, but the mold shape becomes complicated, Slightly inferior in productivity. Generally, in welding a cast product to an extruded material or a drawn material, the number of work steps such as pretreatment such as preheating is increased, and there is room for improvement in terms of welding workability. SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a rear arm of a motorcycle capable of securing sufficient rigidity and improving productivity and weldability. [Means for Solving the Problems] The present invention relates to a pair of left and right arm portions 1 that support the rear wheel 9.
The front parts of the body parts 11 and 10 are connected to each other by a body part 11, and a pivot part pivotally supported by a body frame at the front end of the body part 11.
In the rear arm 8 of the motorcycle formed with 12, the body portion 11 is formed by extruding a light alloy material in the vehicle width direction.
Or a cross-member portion 14 formed by drawing and supporting the rear wheel suspension device, and a flat upper and lower reinforcing portions 15a and 15b extending forward from the upper edge and the lower edge of the cross member portion 14,
The left, right and front ends are opened, and the cross member 14 and the left and right ends of the upper and lower reinforcements 15a and 15b are welded to the left and right arms 10 and 10 to form the body. Part 1
The left and right end openings of 1 are closed by the left and right arms 10,10,
The pivot portion 12 is a tubular body having a length extending over the left and right arms 10, 10, and the pivot portion 12 is connected to the front ends of the left and right arms 10, 10 and the upper and lower reinforcing portions 15 a, The front opening of the left and right arms 10, 10 and the front opening of the body 11 are closed by welding to the front end of the body 15b. Here, the body portion in the present invention is disposed so as to cover the cross member portion and the upper and lower surfaces of the cross member portion, the left and right arm portions and the pivot portion, and passes through the shock absorber of the rear wheel suspension device. And a pair of reinforcing portions formed with through holes to be formed, and includes both the cross member portion and the reinforcing portion formed integrally or separately. Then, at least the cross member portion may be formed by the extrusion or pull-out molding. Needless to say, the entire body portion may be integrally formed. In the present invention, supporting the rear wheel suspension device with the cross member portion means, for example, rotatably supporting one end of a link member that supports the lower end of the shock absorber. Further, the arm portion in the present invention may be formed by extrusion or drawing, or may be formed by sheet metal processing. [Operation] According to the rear arm of the motorcycle according to the present invention, at least the cross member portion of the body portion is formed of a light alloy member formed by extrusion molding or drawing molding in the vehicle width direction. Are arranged in the vehicle width direction. Therefore, a large load from the rear wheel acts in a direction in which the fiber is bent, and as a result, the effect on the bending force of the rear arm increases, and the rigidity as a whole can be improved. In the case of extruded and drawn materials,
Openings are inevitably formed at the left and right ends. In the present invention, since the openings are closed by the left and right arms, no extra member is required and the structure can be simplified accordingly. Furthermore, in the case of extrusion and drawing, mass production is easier than in the case of the above-mentioned conventional casting, which is advantageous in terms of productivity. Further, a cross member portion made of the extruded material or the like of the present invention,
In welding with an arm portion made of a sheet metal processing material or the like, the weldability is better than in the case of welding with a conventional casting, and productivity can be improved from this point as well. In the present invention, the pivot part 12 is connected to the left and right arm parts 10 and 1.
And the front ends of the left and right arms 10 and 10 and the front ends of the upper and lower reinforcements 15a and 15b are welded to the pivot 12 so as to form the left and right arms 10, 10. Since the front end opening of the body 10 and the front end opening of the body 11 are closed, the pivot 12, the left and right arms 10, 10, and the body 11 form a large closed cross-sectional shape (box), The rigidity of the connecting portion of the rear arm suspension device of the rear arm 8 is greatly improved. Embodiment An embodiment of the present invention will be described below with reference to the drawings. FIGS. 1 to 6 are views for explaining a rear arm of a motorcycle according to a first embodiment of the present invention. In the drawing, reference numeral 1 denotes a motorcycle employing the rear arm of the present embodiment, and a body frame 2 of the motorcycle includes a left and right pair of main frames 2a having a steering shaft barrel 2b at a front end and a bracket 2c at a rear end. Each is fixed by welding, and the lower end of the bracket 2c and the lower surface of the front part of the main frame 2a are detachably connected by a pair of left and right down tubes 2d. A front fork 3 is rotatably supported on the steering shaft barrel 2b so as to be rotatable left and right. A front wheel 4 is supported on a lower end of the front fork 3, and a steering handle 5 is fixed on an upper end. I have. Also,
A fuel tank 6 and a seat 7 are provided above the body frame 2.
However, an engine (not shown) is mounted on a lower portion, and a front portion of the vehicle is surrounded by a cowling 2e. The rear arm 8 of the present embodiment is pivotally supported on the bracket 2c of the body frame 2 so as to be vertically swingable.
The rear end of the rear arm 8 supports a rear wheel 9. The rear arm 8 includes a pair of left and right arms 10, a body 11 connecting front ends of the two arms 10, and a body 11.
And a pivot cylinder 12 fixed to the front end of the pivot cylinder. Each of the arms 10 is formed by joining a pair of outer members 10a and inner members 10b formed by molding an aluminum alloy plate into a U-shape in cross section, with their openings facing each other, and welding and fixing the overlapped portions of both. It has a cylindrical shape. And this left,
When viewed from the side, the right arm portion 10 has the largest vertical height near the link support portion of the rear wheel suspension device described later, and gradually decreases from this portion in both the front and rear directions. An axle support bracket 10c is welded and fixed to the rear end of each of the arms 10. An axle 9a of the rear wheel 9 is provided between the left and right support brackets 10c. The body portion 11 is formed by extruding an aluminum alloy so that the fiber direction thereof is in the vehicle width direction. The cross member 14 includes a pair of reinforcing members extending from the upper and lower edges to the front of the vehicle body. The parts 15a and 15b are integrally formed. The cross member 14 is formed in a cylindrical shape including a top wall 11a, a bottom wall 11b, a rear wall 11c, and a reinforcing wall 11d, and the left and right ends are open. Also the bottom wall
A support bracket 11e is integrally formed on the lower surface of 11b, and one end of a link 13a of the rear wheel suspension device 13 is supported by the bracket 11e. The other end of the link 13a is supported near the lower end of the bracket 2c of the vehicle body frame 2, and the lower end of the shock absorber 13b is supported in the middle of the link 13a.
The reinforcing portions 15a and 15b are formed with through holes 11f through which the shock absorbers 13b of the rear wheel suspension device 13 are inserted, and a reinforcing wall 11d is integrally formed between the front portions thereof. The left and right openings of the body portion 11 are
The right arm 10 is covered with a front end 10d of an outer member 10a. The front end 10e of the inner member 10b is in contact with the rear wall 11c of the body 11, and the front ends 10d and 10e and the body
11 is fixed by welding. The pivot cylinder 12 is a round pipe made of aluminum alloy, has a length extending over the left and right arms 10, 10, and is disposed between the front ends of the reinforcing parts 15a, 15b. The reinforcing members 15a, 15b and the outer members 10 of the left and right arms 10
It is fixed by welding to a, and closes the front end openings of the arms 10 and 10 and the front end opening of the body 11. Next, the operation and effect of this embodiment will be described. In the motorcycle 1 according to the present embodiment, a large load from the rear wheel 9 is borne by the body frame 2 via the rear arm 8. In this case, the left and right arm portions 10 of the rear arm 2 are used.
A large bending force acts in the vehicle width direction on the body 11 connecting the two. In the present embodiment, the body 11
Is constituted by an extruding member in the vehicle width direction, the bending force acts in a direction in which the fiber formed by the extrusion molding is bent, so that the resistance to the bending of the body portion 11 is increased, and as a result, the rigidity of the rear arm 8 is increased. Can be improved. Further, the extruded material and the like can be easily mass-produced as compared with a conventional cast product, and can improve productivity. Also, the openings at both ends formed by forming the body portion 11 by the axle-direction push-out member are provided on the left and right arm portions 1.
Since the opening at the front end of the body portion 11 is closed by the pivot cylinder 112 while the opening is closed at 0 and 10, separate members may be required to close the left and right end openings and the front end opening of the body portion 11. And the structure becomes simple. Further, the pivot cylinder 12 has a length extending over the left and right arms 10, 10, and the pivot cylinder 12 has front ends of the left and right arms 10, 10.
And the front end of the body portion 11 is welded and fixed, so that the pivot cylinder 12, the left and right arm portions 10, 10 and the body portion 11 form a large closed cross-sectional shape (box) on the front portion of the rear arm 8. A wheel suspension connection is formed, which can significantly increase the rigidity of the part. Further, since the support bracket 11e for supporting the link 13a of the rear wheel suspension device 13 is also formed at the same time as the extrusion molding, the structure is simplified accordingly. Furthermore,
Looking at the left and right arms 10, this support bracket
Although the maximum bending moment acts around 11e, in the present embodiment, since the arm portion 10 is made of sheet metal, the height in the vertical direction of the portion where the maximum bending moment acts is increased, and The section modulus can be set to a size corresponding to the bending moment, and a mechanically reasonable shape can be manufactured at low cost. In the above embodiment, the left and right arms 10 are formed by sheet metal working. However, as shown in FIG. 7, the arms may be formed by the left and right arms 20 formed by extrusion or drawing. Good. In this way, the number of welded portions of the arm portion can be reduced as compared with the case where the arm portion is formed by sheet metal processing, and the manufacturing cost can be reduced accordingly. Next, a second embodiment of the present invention will be described. 8 to 10 are for explaining the second embodiment, in which the same reference numerals as those in FIGS. 1 to 5 denote the same or corresponding parts. The present embodiment is an example in which only the cross member portion 14 of the body portion 11 is extruded with an aluminum alloy, and the cross member portion 14 is formed integrally with diagonal ribs 14b diagonally. A stepped positioning portion 14a is formed in the vehicle width direction substantially at the center of the top wall portion 11a of the cross member portion 14 and at the lower end swelling of the reinforcing wall 11d. The rear ends of the reinforcing portions 15a, 15b made of stainless steel are welded and fixed, thereby forming the body portion 11. A pivot cylinder 12 is provided between the front ends of the reinforcing portions 15a and 15b.
Are fixed by welding. Further, the top wall portion 11a and the bottom wall portion 11b of the cross member portion 14 are provided.
The front end 10e of the inner member 10b of the arm 10 so as to sandwich
The upper and lower surfaces of the reinforcing portions 15a, 15b and the inner member 10b are located on the same plane as shown in FIG. 10 (b). Further, the outer member 10a of the left and right arm portions 10 is provided so as to sandwich the front end portion 10e of the inner member 10b and the left and right end surfaces of the reinforcing portions 15a and 15b, and to cover the left and right openings of the body portion 11. The body 11, the pivot tube 12, the left and right arms 10 are welded and fixed to each other. According to the present embodiment, since the cross member portion 14 is formed of the pushing member in the vehicle width direction, the rigidity can be improved, the productivity can be improved, and substantially the same effects as those of the first embodiment can be obtained. Further, in the present embodiment, the cross member portion 14 is
Since it is sandwiched and fixed by welding at the front end 10e of b, the rigidity of the joint can be improved accordingly. Furthermore, the reinforcement 15
Since the upper and lower surfaces of the a and 15b and the inner member 10b are located on the same plane, the contact surface of the outer member 10a does not need to be bent, and welding is ensured. Can be improved. [Effects of the Invention] As described above, according to the rear arm of the motorcycle according to the present invention, at least the cross member portion of the body portion is formed of the extruded material or the drawn material in the vehicle width direction, and the pivot portions are left and right. The front ends of the left and right arms, and the front ends of the upper and lower reinforcements are welded to the pivot to weld the front ends of the left and right arms, and the body. Because the front end opening of the rear part is closed, a large closed cross-sectional shape (box body) is configured by the pivot part, the left, right arm, and the body, and the rigidity of the rear arm suspension device connection part of the rear arm is greatly improved. In addition to this, there is an effect that productivity can be improved, and the structure can be simplified by the amount that a separate member is not required to close the opening of the pushing member.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 to 6 are views for explaining a rear arm of a motorcycle according to a first embodiment of the present invention.
2 and 3 are a plan view, a side view, and a front view, respectively, of a rear arm, FIG. 4 is a sectional side view of a body portion, FIG. 5 is an exploded perspective view of the rear arm, and FIG. FIG. 7 is an exploded perspective view showing a modified example of the above embodiment, and FIGS. 8 to 10 are views for explaining a second embodiment of the present invention. 8 and 9 are a perspective view, an exploded perspective view, and a
FIG. 10 (a) is a perspective view showing a joint state between the body part and the arm part, and FIG. 10 (b) is a sectional side view taken along the line XIb-XIb in FIG. 10 (a). In the figure, 1 is a motorcycle, 2 is a body frame, 8 is a rear arm, 9 is a rear wheel, 10 is a left and right arm portion, 10d is a front end portion of an arm portion, 11 is a body portion, and 12 is a pivot cylinder (pivot portion). ), 13 is a rear wheel suspension device, and 14 is a cross member portion.

Claims (1)

(57) [Claims] In a rear arm of a motorcycle, a front part of a pair of left and right arms supporting the rear wheel is connected to each other by a body part, and a pivot part pivotally supported by a body frame is formed at a front end of the body part. The body portion is formed by extruding or drawing out a light alloy material in the vehicle width direction to support a rear wheel suspension device, and a flat plate extending forward from upper and lower edges of the cross member portion. It has upper and lower reinforcements, and the left, right and front ends are open, and the cross member and the left and right ends of the upper and lower reinforcements are welded to the left and right arms. The openings at the left and right ends of the body are closed with left and right arms, and the pivot is formed as a cylinder having a length extending to the left and right arms, and the pivot is connected to the left and right arms. The front end of the arm and the front end of the upper and lower reinforcements Welded to the left, rear arm for a motorcycle is characterized in that to close the front end opening of the front end opening and the body portion of the right arm.