JP2514189B2 - Rear arm structure for motorcycles and tricycles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a rear arm structure for a motorcycle or a front three-wheeled motorcycle having one rear wheel with a wide tire pivotally supported at the rear end of the rear arm. In particular, the present invention relates to a structure that can improve the rigidity of the vehicle body pivotal support portion of the rear arm and the cushion unit mounting portion when the rear wheels are driven by primary and secondary chains that are deviated in the vehicle width direction.

[Conventional technology]

Conventionally, some motorcycles have a rear wheel with a wide low-pressure tire mounted on the rear end of a rear arm pivotally supported by a body frame. In such a vehicle, since the rear wheel is wide, if the drive sprocket on the engine side and the driven sprocket on the rear wheel side are directly connected by one drive chain, the chain projects outward in the vehicle width direction. This is not preferable. Therefore, there is a conventional one in which a pair of primary and secondary intermediate sprockets, which are displaced in the vehicle width direction, are arranged near the pivot portion of the rear arm, and the rear wheels are driven by the primary and secondary chains. .

By the way, there is a case where one cushion unit is arranged between the vicinity of the pivot part of the rear arm and the vehicle body frame to form a rear wheel suspension device.However, when the above-mentioned intermediate sprocket is arranged on such a rear arm, It is necessary to secure a space for disposing the intermediate sprocket in the vicinity of the pivot portion of the rear arm and to secure rigidity that can withstand a large load acting on the cushion unit support portion.

[Problems to be solved by the invention]

On the other hand, the rear wheel cannot be moved far behind the pivot part due to the restriction on the axial distance, so the space between the pivot part of the rear arm and the front edge of the rear wheel is very limited. Therefore, in a vehicle provided with the intermediate sprocket and one cushion unit, a rear arm structure is required which can secure a space for arranging the intermediate sprocket and high rigidity in the extremely limited space.

Therefore, the present invention has been made in order to meet the above-mentioned demand, and can secure a space for disposing the intermediate sprocket in a limited space and improve the rigidity in the vicinity of the cushion unit support portion. Is intended to provide.

[Means for solving problems]

According to the present invention, pivot parts are fixed to the front ends of left and right arm members of a rear arm, and the rear arm is pivotally supported by a pivot shaft penetrating the pivot parts to a lower rear end of a vehicle body frame so as to be vertically swingable. , A rear wheel with a wide tire is supported at the rear end of the rear arm, and a cross member for connecting the left and right arm members is provided at the front portion of the rear arm, and a support bracket fixed to the cross member is provided. The upper end is connected to the lower end of one cushion unit connected to the vehicle body frame, and a support cylinder is inserted and fixed in the vehicle width direction near the rear of the pivot portion of one of the arm members, and An intermediate shaft is rotatably supported by a support cylinder, a primary side intermediate sprocket is provided at an inner shaft end sandwiching the one arm member of the intermediate shaft, and a secondary side intermediate sprocket is provided at an outer shaft end. A rocket is installed, and a primary chain is wound between the primary intermediate sprocket and the drive sprocket on the engine side, and a secondary chain is wound between the secondary sprocket and the driven sprocket on the rear side to drive the rear wheels. In the motorcycles and motorcycles that were
A cover plate formed by bending a strip-shaped plate material into a substantially U-shape in plan view is arranged so as to surround the inside of the primary side intermediate sprocket, and both ends of the cover plate are fixed to the inside of the one arm member. A primary side intermediate sprocket arrangement space is formed between the cover plate and one arm member, and a connecting pipe is installed between the vehicle width direction inner side surface of the cover plate and the other arm member. The end portions are fixed to the cover plate and the other arm member, respectively, and a notch along the cross-sectional shape of the connecting pipe is formed in the lower part of the support bracket made of a plate material, and the notch portion is the vehicle width of the connecting pipe. Is fixed to the outer periphery at the center in the direction, and the lower end of the cushion unit is pivotally supported on the upper end of the support bracket, and the cross member is , A lower reinforcing plate having a front and rear edge portions fixed to each other in a solid shape, and inserting and arranging the connecting pipe in the vehicle width direction so as to divide the inner space of the cross member into front and rear closed cross sections, The inner surfaces of the upper and lower reinforcing plates are brought into contact with the upper and lower surfaces of the outer periphery of the connecting pipe to fix them, and notches are formed in the upper and lower reinforcing plates to insert the support brackets. A part of the upper and lower reinforcing plates is fixed at the contact portion between the notch and the lower side surface of the support bracket, and at the fixed portion between the one arm member to which the intermediate shaft is fixed and the cross member. It is characterized in that a notch is formed in conformity with the outer shape of the cover plate in a substantially U shape in a plan view, and the notch and the inner side surface of the cover plate are fixed to each other.

[Action]

In the rear arm structure according to the present invention, the cross member is formed in a middle shape by the upper and lower reinforcing plates, the connecting pipe is penetrated so as to divide the internal space of the cross member into the front and the rear, and the upper and Since the inner surfaces of the upper and lower reinforcing plates were brought into contact with the lower surface to secure both,
The cross member formed by the upper and lower reinforcing plates is reinforced by the connecting pipe to increase the rigidity of the cross member.

Also, since the lower part of the support bracket is fixed to the outer periphery of the rear side of the connecting pipe, and the contact points between the upper and lower reinforcing plates and the lower side faces of the support bracket are fixed, the load from one cushion unit is To the upper and lower reinforcing plates and the connecting pipe.

Furthermore, since the outer surface of the cover plate and the upper and lower reinforcing plates are fixed to each other at the fixing portion between the arm member provided with the intermediate shaft and the cross member, even if the cross member is notched to accommodate the primary side intermediate sprocket. , Is reinforced with a strip-shaped cover plate.

Therefore, when the sprocket arranging space is secured by fixing the primary and secondary side sprockets to the intermediate shaft disposed in the middle of one arm member, one rear arm provided with the intermediate shaft is provided with Even if the cushion unit is connected, the rigidity of the front portion of the rear arm is sufficiently secured.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

1 to 4 are views for explaining a rear arm structure according to an embodiment of the present invention.

In the figure, reference numeral 1 is a motorcycle to which the structure of this embodiment is applied. An engine 3 is mounted substantially in the center of a body frame 2 of the motorcycle 1, and a front fork 5 supporting a front wheel 4 is pivotally supported at a front end portion thereof. A steering handle is provided at an upper end of the front fork 5. 6 is fixed. A fuel tank 7 and a seat 8 are mounted on the upper part of the vehicle body frame 2.

A rear arm 9 is pivotally supported at the lower rear end of the vehicle body frame 2, and a rear wheel 10 with a wide low-pressure tire is rotatably supported at the rear end of the rear arm 9. The rear arm 9 mainly has a structure in which left and right arm members 9a, 9b made of steel pipe having a rectangular cross section are connected by a cross member 17. Cylindrical left and right pivot parts 10a and 10b are fixed to the front end portions of the left and right arm members 9a and 9b, respectively, and the pivot parts 10a and 10b pass through the left and right pivot parts 10a and 10b. It is pivotally supported by the support bracket portion 2a. The rear end support portion 3a of the engine 3 is fixed between the left and right pivot portions 10a and 10b via the pivot shaft.

Further, the intermediate shaft support cylinder 11 is provided at the front portion of the left arm member 9a.
Is fixed in the vehicle width direction, and primary and secondary intermediate sprockets 12a and 12b are fixed to both ends of an intermediate shaft rotatably inserted in the support cylinder 11. This primary side intermediate sprocket 12a and the drive sprocket 3b on the engine 3 side
A primary chain 20a is wound between the secondary chain 20a and the secondary intermediate chain sprocket 12b, and a secondary chain 20b is wound between the driven sprocket 10a on the rear wheel 10 side. Reference numeral 19 is a chain cover that covers the drive side portion of the secondary chain 20b.

The left arm member 9a is provided with a cover plate 13 formed by bending a strip plate in a substantially U-shape in a plane so as to surround the primary side intermediate sprocket 12a, and both ends thereof are on the inner surface of the left arm member 9a. It is welded and fixed, thereby forming a primary side intermediate sprocket arrangement space 13a.

The left end of a steel pipe connecting pipe 14 is fixed to the inner surface of the cover plate 13 in the vehicle width direction.
The right end of 14 penetrates the right arm member 9b and projects outward, and the outer end portion is welded and fixed to the right arm member 9b.

A cushion unit support bracket 15 is arranged at the center of the connecting pipe 14 in the vehicle width direction. The lower portion of the bracket 15 is cut out in a semicircular shape following the shape of the connecting pipe 14, the cutout portion 15a is welded and fixed to the connecting pipe 14, and the cushion unit is provided at the upper end portion thereof.
The lower end of 16 is pivotally supported.

Further, the cross member 17 has upper and lower reinforcing plates 17a,
The front and rear edges of 17b are welded and fixed to each other, and the left and right ends of the cross member 17 are welded and fixed to the left and right arm members 9a and 9b. The connecting pipe 14 is disposed in the cross member 17 in the vehicle width direction, and the upper and lower reinforcing plates 17a and 17b are in contact with the upper and lower surfaces of the connecting pipe 14 and through the welding opening 17c. Are welded together. In this way, the inner space of the cross member 17 is divided into the front and rear portions by the connecting pipe 14, and as a result, the front and rear closed cross-sections 18a, 18a, extending in the vehicle width direction are formed in the front and rear portions of the connecting pipe 14, respectively. 18b is formed.

Further, the upper and lower reinforcing plates 17a, 17b are formed with notches 17d through which the support bracket 15 is inserted,
The notch 17d is welded and fixed to the side surface of the support bracket 15. Also, the upper and lower reinforcing plates 17a, 17b described above.
The cover plate 13 portion of
A notch 17e is formed along the outer shape of the U-shape in plan view, and the notch 17e is welded and fixed to the inner surface of the cover plate 13.

In this way, the cross member 17 includes the support bracket 15, the cover plate 13, and the left and right arm members 9a and 9a.
It is welded and fixed to b, connecting and fixing these members to each other.

The procedure for assembling the rear arm 9 will now be described. The rear arm 9 is constructed by first referring to the cover plate 13, the connecting pipe 14, the support bracket 15, and the upper and lower reinforcing plates 1.
7a and 17b are welded and fixed to each other to form a sub-assembly, and then the left and right arm members 9a and 9b are brought into contact with each other to be welded and fixed, and thus assembled.

 Next, the function and effect of this embodiment will be described.

As described above, in the structure in which one cushion unit is arranged between the vicinity of the pivot portion of the rear arm and the vehicle body frame, a large load is applied to the rear arm because the cushion unit support portion of the rear arm is near the fulcrum of the rear arm. Therefore, it is necessary to improve the rigidity while securing the space for disposing the intermediate sprocket in a limited space.

In the structure of this embodiment, the thick and concave cover plate 13 is fixed to the inside of the left arm member 9a, and the cover plate 13 and the right arm member 9b are connected by the connecting pipe 14, so that the space is limited. Sub-rocket placement space 13a
Can be secured.

In addition, the cover plate 13, the connecting pipe 14, the support bracket 15 and the left and right arm members 9a and 9b are reinforced by reinforcing plates 17a and 17b.
And the front and rear parts of this connecting pipe 14,
Since the closed sections 18a and 18b are formed by the lower reinforcing plates 17a and 17b, the left and right arm members are limited in a limited space.
The rigidity of the connecting portions of 9a and 9b can be greatly improved. Further, in this case, since the rigidity of the mounting portion of the support bracket 15 is increased, the support bracket 15 itself may have a simple shape, and since it is not necessary to reinforce the support bracket 15, the space required for the support bracket 15 may be increased. Absent.

Further, a support cylinder 11 is disposed so as to penetrate through the left arm member 9a in the vicinity of the rear of the pivot portion in the vehicle width direction, and a primary side and a secondary side are provided at both ends sandwiching an arm member of an intermediate shaft pivotally supported by the support cylinder 11. Since the side intermediate sprockets 12a, 12b are mounted and the primary and secondary side chains 20a, 20b are wound to drive the rear wheel 10, the distance between the left and right pivot parts 10a, 10b is usually a tire width. It can be the same as the rear arm that supports the rear wheels.

Generally, the vicinity of the rear arm pivot portion at the rear end of the lower portion of the vehicle body frame is the position where the driver's feet are placed. Therefore, when the distance between the left and right pivot portions increases, the rear arm pivotal support portion of the vehicle body frame projects outward and restricts the foot placement position, which necessitates a major design change of the vehicle body frame. For example, when the intermediate shaft is arranged between the left and right pivot parts, the space between the left and right pivot parts is widened by the space for disposing the intermediate shaft, and the foot mounting position is widened. It is necessary to change the design of the body frame. In the rear arm of this embodiment, since the intermediate shaft is arranged rearward of the pivot part, such a problem can be avoided.

In the above embodiment, the motorcycle has been described, but the present invention can be applied to a front two-wheeled vehicle and a rear one-wheeled motorcycle.

〔The invention's effect〕

As described above, according to the rear arm structure for a motorcycle according to the present invention, the cross member is formed in a middle shape by the upper and lower reinforcing plates, and the connecting pipe is penetrated so as to divide the internal space into front and rear. Since the inner surfaces of the upper and lower reinforcing plates are brought into contact with the upper and lower surfaces on the outer circumference of the connecting pipe to fix them to each other, the cross member formed by the upper and lower reinforcing plates is reinforced by the connecting pipe. The rigidity can be increased.

Further, since the lower part of the support bracket is fixed to the outer periphery of the rear side of the connecting pipe, and the contact points between the upper and lower reinforcing plates and the lower side faces of the support bracket are fixed, the load from one cushion unit is supported by the support bracket. The upper and lower reinforcing plates and the connecting pipes are dispersed to improve the support force of the cushion unit.

Furthermore, since the outer surface of the cover plate and the upper and lower reinforcing plates are fixed to each other at the fixing portion between the arm member provided with the intermediate shaft and the cross member, even if the cross member is notched to accommodate the primary side intermediate sprocket. , With a strip-shaped cover plate.

Therefore, when the sprocket arranging space is secured by fixing the primary and secondary side sprockets to the intermediate shaft disposed in the middle of one arm member, one rear arm provided with the intermediate shaft is provided with Even if the cushion unit is connected, the strength of the front portion of the rear arm can be sufficiently secured. Moreover, each member can be made of sheet metal, and the members can be sub-assembled and then assembled as a whole, so that the rear arm can be easily manufactured.

[Brief description of drawings]

1 to 4 are views for explaining a rear arm structure of a motorcycle according to an embodiment of the present invention. FIG. 1 is a plan view of the rear arm portion, and FIGS. II-II line sectional view, III-III line sectional view of FIG. 1, 4th
The figure is a side view of a motorcycle to which the embodiment is applied. In the figure, 1 is a motorcycle, 2 is a body frame, 9 is a rear arm, 9a and 9b are left and right arm members, 10 is a rear wheel, and 12 is a rear wheel.
a and 12b are primary and secondary side intermediate sprockets, 13 is a cover plate, 13a is a primary intermediate sprocket arrangement space, 14
Is a connecting pipe, 15 is a support bracket, 16 is a cushion unit, 17 is a cross member, 17a and 17b are upper and lower reinforcing plates, 18a and 18b are front and rear closed cross sections, and 20a and 20b are primary and secondary chains. is there.

Claims (1)

(57) [Claims] 1. A pivot part is fixed to the front ends of the left and right arm members of the rear arm, and the rear arm is pivotally supported on a lower rear end of a vehicle body frame by a pivot shaft penetrating the pivot part. At the same time, one rear wheel with a wide tire is supported at the rear end of the rear arm, and a cross member for connecting the left and right arm members is provided at the front portion of the rear arm, and a support bracket fixed to the cross member. The lower end of one cushion unit whose upper end is connected to the vehicle body frame is connected to, and a supporting cylinder is inserted and fixed in the vehicle width direction near the rear of the pivot portion of one of the arm members, An intermediate shaft is rotatably supported by the support cylinder, a primary side intermediate sprocket is provided at an inner shaft end sandwiching the one arm member of the intermediate shaft, and a secondary side intermediate sprocket is provided at an outer shaft end. Install the sprocket, and wrap the primary chain between the primary intermediate sprocket and the drive sprocket on the engine side, and the secondary chain between the secondary sprocket and the driven sprocket on the rear wheel side. In a motorcycle that is driven, a cover plate formed by bending a strip-shaped plate material into a substantially U shape in plan view is arranged so as to surround the inside of the primary side intermediate sprocket, and both ends of the cover plate are A primary side intermediate sprocket arrangement space is formed between the cover plate and one arm member by being fixed to the inside of one arm member, and between the inner side surface of the cover plate in the vehicle width direction and the other arm member. A connecting pipe is erected, and each end of the connecting pipe is fixed to the cover plate and the other arm member respectively. A notch is formed in the lower portion of the support bracket along the cross-sectional shape of the connecting pipe, and the notch is fixed to the center of the connecting pipe in the vehicle width direction and to the outer periphery of the rear side of the supporting bracket. The lower end of the cushion unit is rotatably supported at the upper end, and the cross member is made of a middle shape in which the front and rear edges of the upper and lower reinforcing plates are fixed, and the inner space of the cross member is closed at the front and rear. The connecting pipe is inserted and arranged in the vehicle width direction so as to be divided into sections, and the inner surfaces of the upper and lower reinforcing plates are brought into contact with the upper and lower surfaces of the outer periphery of the connecting pipe to fix them together. One arm member in which a notch into which the support bracket is inserted is formed in the reinforcing plate, and the contact portion between the notch and the lower side surface of the support bracket is fixed, and further the intermediate shaft is fixed. At the fixing portion with the cross member, a part of the upper and lower reinforcing plates is cut out in accordance with the outer shape of the cover plate in a substantially U shape in plan view, and the cutout portion and the inner surface of the cover plate are fixed. The rear arm structure of motorcycles and motorcycles characterized by the above.