JP3198464B2 - Damper arrangement structure for rear wheel suspension system for motorcycle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear wheel suspension system for a motorcycle, and more particularly to an improvement in the arrangement of a rotary damper when a rotary damper is employed.

[0002]

2. Description of the Related Art Conventionally, a rear wheel suspension system for a motorcycle employs a structure in which a shock absorber composed of a coil spring and a telescopic tubular damper is interposed between a rear arm and a body frame. And recently, the above-mentioned shock absorber is one,
In general, this is disposed directly or via a link mechanism between the vicinity of the pivot portion of the rear arm and the lower portion of the fuel tank of the vehicle body frame or the lower portion of the seat (see, for example, Japanese Unexamined Patent Application Publication No. -120585).

However, in the above-mentioned conventional apparatus, the space for arranging the parts located in the center of the vehicle is occupied by the shock absorber, which makes it difficult to secure a space for arranging other in-vehicle parts such as an air cleaner and a battery. There is a problem that space efficiency is poor.

[0004]

On the other hand, at present, the present inventors are studying to adopt a leaf spring instead of the coil spring and to employ a rotary damper instead of the telescopic damper. . In the case where a suspension device including the leaf spring and the rotary damper is employed, the space efficiency can be expected to be improved.However, depending on the arrangement structure of the rotary damper, the rear arm of the rotary piston of the rotary damper is particularly provided. There is a concern that the mechanism for transmitting the operation becomes complicated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the conventional structure and the problems in the case of employing a leaf spring and a rotary damper, and can improve the space efficiency and complicate the operation transmission mechanism. It is an object of the present invention to provide a damper arrangement structure of a motorcycle rear wheel suspension device that can avoid the above problem.

[0006]

SUMMARY OF THE INVENTION The present invention comprises a shock absorbing spring for alleviating a shock applied to a rear wheel from a road surface, and a damper for suppressing irregular vertical vibration of the rear wheel. The rear arm has a pair of left and right pivot pipes provided at a front end thereof disposed inside left and right rear arm brackets. A long strip-shaped plate that is supported by the vehicle body fixing portion via a bracket and a pivot shaft inserted through the left and right pivot pipes, and extends from the lower front portion of the crankcase of the engine to the lower front portion of the rear arm of the engine. The leaf spring is disposed below the engine in the front-rear direction of the engine, and the front end of the leaf spring is supported by a support bolt near the front of the crankcase of the vehicle body fixing part. A swinging support, a rear end portion swingably supported by the rear arm, and a fulcrum for bending the leaf spring upward with the elevation of the rear arm, substantially at the center of the leaf spring in the longitudinal direction thereof. The damper is disposed so as to abut on the damper case, and a rotary piston is rotatably arranged in a damper case, and a rotary shaft thereof is formed in a cylindrical shape, and the damper case is provided between the left and right pivot pipes of the rear arm. Is disposed, the pivot shaft of the rear arm is coaxially inserted into the cylindrical rotation shaft of the rotation piston, and the rotation shaft is fixed to the rear arm, while the damper case is fixed to the body frame or the engine. Features.

[0007]

According to the damper arrangement of the rear wheel suspension system of the present invention, the rotation axis of the rotary piston is made coaxial with the pivot axis of the rear arm, so that the rotation angles of the rear arm and the rotary piston coincide with each other. There is no need for a link mechanism between the rotary arm and the rotary piston, and as a result, the structure of the mechanism for transmitting the operation of the rear arm to the rotary damper is extremely simplified.

In addition, since the rotating shaft is made coaxial with the pivot shaft, the rotary damper comes closer to the engine, so that mass concentration can be achieved. Further, since the relatively lightweight rotating piston is fixed to the rear arm and the relatively heavy damper case is fixed to the body frame or the engine, the unsprung load can be reduced accordingly.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 to 5 are views for explaining a damper arrangement structure of a rear wheel suspension device for a motorcycle according to an embodiment of the present invention. FIG. 1 is a side view of the bumper arrangement structure, and FIG. Fig. 3, Fig. 3 and Fig. 4 are sectional views taken along the line III-III in Fig. 1, and IV-IV.
5 is a side view of a motorcycle having the structure.

In FIG. 1, reference numeral 1 denotes a motorcycle employing the embodiment. Body frame 2 of the motorcycle 1
Is a so-called double cradle type, in which the front ends of a pair of left and right diagonally downwardly extending tank rails 4, 4 are connected to the head pipe 3, and a rear arm bracket 5 is connected to the rear ends of the tank rails 4, 4. , 5 and the lower end of each rear arm bracket 5 and the head pipe 3 are connected to the left,
It has a structure connected by a pair of right down tubes 6,6. The rear arm brackets 5, 5 are connected by an upper cross pipe 5b and a lower cross pipe 5c.
In addition, 7 is a tension pipe for reinforcement connecting the tank rail 4 and the down tube 6, 8 is a seat rail,
Reference numeral 9 denotes a back stay for supporting the rear end of the seat rail 8.

A fuel tank 10 is provided on a tank rail 4 of the body frame 2, an air cleaner 10a is provided inside the tank 10, a seat 11 is provided on a seat rail 8, and a tank rail 4, a rear arm bracket 5, The engine 12 is mounted in the cradle constituted by the down tube 6. In addition, 10b is a battery.

The engine 12 is of an air-cooled 4-cycle parallel 4-cylinder type. A cylinder block 14 and a cylinder head 15 are stacked in a forwardly inclined state at the front of a crankcase 13 integrated with a transmission case. The head cover 16 is put on the upper mating surface of the cylinder head 15. 28 is the crankcase 1
3 is an oil pan attached to the bottom surface.

In the engine 12, the front boss 13a of the crankcase 13 is bolted and fixed to a front bracket 6a fixed to the down tube 6, and the rear boss 13b is fixed to the rear arm bracket 5. It is mounted on the vehicle body frame 2 by being fixed to the rear suspension pipe 5d with bolts.

The four exhaust pipes 18a of the exhaust device 17 are connected to each exhaust port opened on the front wall of the cylinder head 15. The exhaust pipes at the left and right ends of the exhaust pipe 18a are arranged on the left side of the vehicle and the two central exhaust pipes are arranged on the right side of the vehicle and pass under the oil pan 28. It is connected to the junction pipe 19a. Further, the respective merging pipes 19a extend leftward and rightward near the rear end of the oil pan 28, and left and right silencers 20a are respectively connected to the respective side widening ends, and a rear arm described in detail below. The left and right sides of 21 extend obliquely upward.

The rear arm 21 has a pair of left and right rectangular cylindrical arm bodies 22a and 22b fixed to the front ends of a pair of circular cylindrical pivot pipes 23, respectively.
The rear portions are connected and fixed by a rectangular cross member 24, and the left and right arm bodies 22a, 22
A rear wheel 26 is pivotally supported by an axle 25 fixedly inserted between rear ends of the rear wheels 2b. The pivot pipe 23 is supported by a pivot shaft 27 inserted therethrough via a bearing 23a, and the pivot shaft 27 is fixedly fastened to the left and right rear arm brackets 5 with nuts 27a.

A rear wheel suspension device 29 is provided from below the front portion of the rear arm 21 to below the engine 12. The rear wheel suspension device 29 is disposed between the rear arm 21 and the bottom surface (the vehicle body fixed portion) of the engine 12 and reduces a shock applied to the rear wheel 26 from the road surface. Engine 12
And a rotary damper 30 for suppressing irregular vertical vibration of the rear wheel 26.

The rear end 31a of the leaf spring 31 is swingably supported by the rear arm 21 via a rear spring bracket 43 and an initial load adjusting mechanism 63, and the front end 31b is supported by a front spring bracket 47 via the front spring bracket 47. Crankcase 1
3 is supported by the bottom surface (vehicle fixing portion).

The initial load adjusting mechanism 63 has a structure in which an upper bracket 64 and a lower bracket 66 are connected by adjusting screws 65. In addition, 65a and 65b are lock nuts of right-handed screw and left-handed screw. The upper bracket 64 is swingably connected to a support bracket 24a fixed to the cross pipe 24 by connecting bolts 41a and nuts 41b. The lower bracket 66 is connected to the rear spring bracket 43 via a rubber bush 42. Are linked. The rubber bush 42 is used for the outer pipe 4
A rubber ring 42c is inserted and baked and fixed between the inner pipe 42a and the inner pipe 42b, and the outer pipe 42a is connected to the connecting portion 4 of the rear spring bracket 43.
It is press-fitted and fixed in 3a. The initial load can be set to a desired value by rotating the adjusting screw 65 to adjust the distance between the rear end 31a of the leaf spring 31 and the rear arm 21.

The leaf spring 31 is a resin band-shaped plate extending in the vehicle front-rear direction below the oil pan 28, and gradually becomes thinner from the center toward the front and rear ends. The rear end 31a of the leaf spring 31 is fixed on a support portion 43b of the rear spring bracket 43 by a pressing plate 43c and a fixing bolt 45. This leaf spring 3
The front end portion 31b of the first support portion 4 is a support portion 4 of the front spring bracket 47.
7b is fixed by a support plate 48a and bolts 48b. Connecting portion 47a of the front spring bracket 47
Is swingably connected to a support boss 13c formed at the front end of the bottom surface of the crankcase 13 by a support bolt 49a.

Further, a support lever 50 serving as a fulcrum when the leaf spring 31 is deformed is disposed above a substantially central portion in the longitudinal direction of the leaf spring 31. The support lever 50 is a metal plate having a lower surface formed in an arc shape, and the arc surface is in contact with the upper surface of the leaf spring 31. Since the lower surface of the support lever 50 has an arc shape, the leaf spring 31
The contact point changes as the rear arm 21 swings, so that the spring characteristic can be made progressive and the concentrated load can be prevented from acting on the spring. Also, this support lever 50
The support boss 50a formed at the front end of the oil pan 28 is supported by a support shaft 52 on the support boss 28a integrally formed on the lower surface of the oil pan 28. Note that a rubber sheet may be attached to the lower surface of the support lever 50. On the upper surface of the support lever 50, a block 62 for absorbing small irregularities on the road surface is provided. The block 62 is made of an elastic material such as rubber, and is fitted and mounted in a mounting recess 28 c formed in the bottom of the oil pan 28.

The rotary damper 30 includes a case body 32
a and a lid 32b, a substantially plate-shaped wing-shaped rotary piston 33 that accommodates and arranges a substantially fan-shaped damper case 32 that defines the interior of the damper case into two chambers is provided. It has a structure in which the rotating shaft 67 is inserted into the upper end 33a and connected with the pin 67c. The damper case 32 has upper and lower flanges 32d, 32d.
e is an upper portion formed at the rear of the crankcase 13,
It is fixed to the engine 12 by being bolted and fixed to the lower boss portions 36a and 13b. The lid 3
A plurality of passages are formed in 2b to communicate the two chambers defined above, and a throttle mechanism is arranged in each of the passages.

The rotating shaft 67 has a cylindrical shape, and the pivot shaft 27 is inserted into the center of the rotating shaft 67 via a collar 27b. A needle bearing is provided between the collar 27b and the rotating shaft 67. 67d is interposed. A damper arm 67b is fixed to the rotating shaft 67. The rear end 67a of the damper arm 67b is
4 is bolted and fixed to a connection bracket 24b fixed to the connector bracket 4. As a result, the rotating piston 33 of the rotary damper 30 rotates back and forth with the rotary shaft 67 in accordance with the vertical swing of the rear arm 21.

Next, the operation and effect of this embodiment will be described. In the present embodiment, when the rear wheel 26 rides on, for example, a convex portion of a road surface, the rear arm 21 is raised by the impact force, and accordingly, the rear end 31a of the leaf spring 31 is moved to the initial load adjusting mechanism 63 and the rear spring bracket. The leaf spring 31 is bent via the arc-shaped lower surface of the support lever 50 as a fulcrum, and the impact force is reduced by the spring force at this time. Further, as the rear arm 21 is raised and lowered, the rotary piston 3 in the rotary damper 30 is moved.
3 rotates, and the hydraulic oil in each room passes through the throttle mechanism in the oil passage, so that a damping force is generated.

In the rear wheel suspension device 29 performing such an operation, the rotating shaft 67 of the rotating piston 33 is connected to the rear arm 2.
1 is made coaxial with the pivot shaft 27 of the
The rotation angle of 3 is the same as the swing angle of the rear arm 21. Therefore, the rear arm 2
In the case of transmitting the up and down motion of the first member, the rotary shaft 67 can be fixedly connected directly to the cross member 24 without the intervention of a link mechanism or the like, and the transmission mechanism of the above operation is extremely simple.

Further, since the rotary shaft 67 is coaxial with the pivot shaft 27, the entire rotary damper 30 can be brought close to the engine 12, so that the mass can be concentrated. In this case, since the damper case 32 is fixed to the crankcase 13, the rotary damper 30 can be brought closer to the engine 12 from this point as well. By the way, in the case of fixing to a rear arm bracket or the like, a cross pipe crossing the portion is required, which complicates the structure and hinders the proximity of the engine.

The relatively lightweight rotary piston 33 of the rotary damper 30 is fixed to the rear arm 21 and the relatively heavy damper case 32 is fixed to the engine 12, so that the unsprung load is reduced accordingly. It is advantageous as a suspension device. The damper case may be formed integrally with the crankcase, or the damper case may be fixed to the vehicle body frame.

Furthermore, since the rear end 31a of the leaf spring 31 is connected to the rear arm 21 by the initial load adjusting mechanism 63, the initial load adjusting mechanism 63 can be directly operated from below the vehicle without removing the cover or the like. In addition, maintainability such as adjustment work of initial load and attachment / detachment work can be secured. In addition, since the initial load adjusting mechanism 63 is disposed at the rear end of the leaf spring 31, there is an advantage that, for example, flying stones and the like from the road surface are less likely to be hit than when the initial load adjusting mechanism 63 is disposed at the front end.

A support lever 5 serving as a fulcrum of the leaf spring 31
The contact surface of the leaf spring 31 is gradually changed since the contact surface of the leaf spring 31 is gradually changed since the contact surface of the plate 0 is formed in an arc shape and the support lever 50 is swingable. This is advantageous in securing the strength of the spring because it is possible to avoid the problem.

[0029]

As described above, according to the damper arrangement structure of the rear wheel suspension for a motorcycle according to the present invention, the rotating shaft of the rotating piston is coaxial with the pivot shaft of the rear arm.
The swing angle between the rear arm and the rotating piston coincides, so that no link mechanism is required between the rear arm and the rotating piston, and the structure of the mechanism for transmitting the operation of the rear arm to the rotary damper is extremely simple. . In addition, since the rotating shaft is coaxial with the pivot shaft, the rotary damper is located closer to the engine, so that the mass can be concentrated and the space efficiency can be improved. Since the case is fixed to the body frame or the engine, the unsprung load can be reduced accordingly. Furthermore, since the leaf spring is arranged below the engine in the vehicle front-rear direction, the dead space below the engine can be effectively used, and the space efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a side view showing a bumper arrangement structure of a rear wheel suspension device for a motorcycle according to one embodiment of the present invention.

FIG. 2 is a partial cross-sectional plan view of the structure of the embodiment.

FIG. 3 is a sectional view taken along line III-III of FIG. 1;

FIG. 4 is a sectional view taken along line IV-IV of FIG. 1;

FIG. 5 is a side view of a motorcycle having the structure of the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Motorcycle 5 Rear arm bracket 12 Engine 13 Crankcase 21 Rear arm 23 Pivot pipe 27 Pivot shaft 29 Rear wheel suspension device 30 Rotary damper 31 Leaf spring 32 Damper case 33 Rotating piston 50 Support lever (fulcrum) 67 Rotating shaft

Claims (1)

(57) [Claims] 1. A motorcycle according to claim 1, further comprising a buffer spring for reducing shock applied to the rear wheels from the road surface, and a damper for suppressing irregular vertical vibration of the rear wheels. In the arrangement of the damper of the rear wheel suspension device, in the rear arm, a pair of left and right pivot pipes provided at the front end are disposed inside the left and right rear arm brackets, and are inserted through the left and right rear arm brackets and the left and right pivot pipes. The cushioning spring is supported by a fixed body portion via a pivot shaft, and the cushioning spring is a long band-shaped plate spring extending from below the front portion of the crankcase of the engine to below the front portion of the rear arm. The front end of the leaf spring is swingably supported by a support bolt near a front part of the crankcase of the vehicle body fixing part, and the rear end is disposed in the front-rear direction. It was arranged to contact with the supporting point for bending the plate spring upward with increasing the rear arm in the longitudinal direction substantially the upper surface of the center of the plate spring swingably supported by the rear arm, the damper The rotary piston is rotatably arranged in a damper case, the rotary shaft is cylindrical, and the rotary shaft is cylindrical.The damper case is arranged between the left and right pivot pipes of the rear arm, and the rotary piston cylinder A rear wheel suspension system for a motorcycle, wherein the pivot shaft of the rear arm is coaxially inserted into the rotary shaft and the rotary shaft is fixed to the rear arm, while the damper case is fixed to a body frame or an engine. Damper arrangement structure.