JPH06179387A - Rear wheel suspension device for motor-bicycle - Google Patents

Abstract

PURPOSE:To reasonably transmit the self-aligning torque of a torsion bar to a swing arm so as to smoothen the rotation of the wing arm, and concurrently make a motor-bicycle light in weight. CONSTITUTION:In a motor-bicycle where a swing arm 19 extended afterward is rotatably pivoted onto a pivot axis 18 fitted onto a body frame 2 in the width direction, and a rear wheel 20 is rotatably supported onto the free end of the swing arm 19, a torsion bar 33 which is in parallel with the pivot axis 18 is provided for the body frame 2, and the center section of the torsion bar 33 is fixed onto the body frame 2. Meanwhile, both the end sections of the torsion bar 33 are supported by the body frame 2 in such a way that the end sections can be elastically twisted within an elastic range with respect to its center section, so that a torque transmitting means 39 (torque arm 40, torque rod 41 and torque brackets 42) which twists both the end sections of the torsion bar 33 in response to the rotation of the swing arm 19, is interposed between each end section of the torsion bar 33 and each right or left side of the swing arm 19.

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 using a torsion bar instead of a coil spring.

[0002]

2. Description of the Related Art In a general motorcycle, a pivot shaft extending in the vehicle width direction is mounted on a vehicle body frame, and a swing arm extending rearward is rotatably attached to the pivot shaft. The body layout is such that the rear wheel is pivotally supported at the free end (rear end).

A rear wheel suspension device (suspension device) is provided between the swing arm and the body frame.
The swing shock of the swing arm due to the vertical movement of the rear wheel is attenuated, and the position of the swing arm is restored.

As a rear wheel suspension system of a motorcycle, a mainstream system in recent years is one in which a shock absorber, which is a combination of a coil spring and a hydraulic damper, is connected to a vehicle body frame and the other end is connected via a link or the like. Is connected to the base end of the swing arm.

However, in the case of such a rear wheel suspension system, the weight of the shock absorber is heavy and the vehicle weight is heavy. Further, since the heavy shock absorber is installed relatively above the vehicle body, the center of gravity of the vehicle body is increased. There was a drawback that the cost was high.

For this reason, a rear wheel suspension system has been proposed which uses a torsion bar instead of the shock absorber.
This is one in which a torsion bar is provided in the vehicle body frame in parallel with the pivot shaft, one end of this torsion bar is fixed to the vehicle body frame, and the other end is connected to one side of the swing arm via a link or the like. When the swing arm rotates, the torsion bar is twisted, and the position of the swing arm is restored by the restoring torque due to the elasticity of the torsion bar.

In such a rear wheel suspension system, since the torsion bar is lightweight and the torsion bar can be installed in the lower portion of the vehicle body, it is possible to contribute to weight reduction and low center of gravity of the vehicle body.

[0008]

However, in the conventional rear wheel suspension system using the torsion bar, one end of the torsion bar installed in the vehicle width direction is connected to one side of the swing arm via a link or the like as described above. Therefore, the restoring torque of the twisted torsion bar is always applied to only one side of the swing arm to twist the swing arm.

For this reason, it is difficult for the swing arm to rotate smoothly, which is not practical, and it is necessary to reinforce the swing arm to prevent it from twisting.
Since this increases the weight of the swing arm, the merit of using a lightweight torsion bar has been offset.

The present invention has been made in view of the above problems, and it is possible to smoothly transmit the restoring torque of the torsion bar to the swing arm to smoothly rotate the swing arm and at the same time reduce the vehicle weight. It is an object to provide a rear wheel suspension device for a motorcycle.

[0011]

In order to achieve the above object, a rear wheel suspension system for a motorcycle according to the present invention includes a swing shaft extending rearward on a pivot shaft provided in a vehicle body frame in a vehicle width direction. In a motorcycle rotatably pivotally mounted and having a rear wheel pivotally supported on a free end of the swing arm, a torsion bar parallel to the pivot axis is provided on a vehicle body frame, and a central portion of the torsion bar is provided. While being fixed to the body frame, both ends of the torsion bar are supported on the body frame so that they can be twisted within the elastic range with respect to the center part, and a swing is made between both ends of the torsion bar and the left and right sides of the swing arm. It is characterized in that torque transmitting means for twisting both ends of the torsion bar according to the rotation of the arm is provided.

[0012]

With this structure, the swinging torque of the swing arm that is rotated from the initial position with the pivot shaft as the fulcrum is applied to both ends of the torsion bar via the torque transmitting means, and both ends of the torsion bar are added. Are twisted in the same direction with respect to the central part. Then, when both ends of the torsion bar are restored from the twisted state due to the elasticity of the torsion bar, this restoring torque is evenly applied to the left and right sides of the swing arm via the torque transmitting means, so that the swing arm is not twisted and is initially moved. Returned to position.

For this reason, the swing arm can be rotated very smoothly, and at the same time, since the swing arm is not twisted, it is not necessary to reinforce the swing arm, and in addition to the use of a lightweight torsion bar, the vehicle weight is greatly reduced. Can be achieved. Further, the use of the torsion bar realizes a low center of gravity of the vehicle body.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a left side view of a motorcycle to which the present invention is applied. The motorcycle 1 is provided with, for example, a diamond-shaped vehicle body frame 2, and the vehicle body frame 2 includes a head pipe 3 located in the forehead and a pair of left and right extending from the head pipe 3 obliquely rearward and downward. The main pipe 4, an engine supporter 5 provided over the head pipe 3 and the main pipe 4, a pair of left and right center plates 6 fixed to the rear end of the main pipe 4, an intermediate portion of the main pipe 4, and a rear portion. It has a pair of left and right seat rails 7 and a seat stay 8 that extend obliquely rearward and upward from the ends. The left and right members 4, 6, 7, 8 are connected to each other by a bridge member (not shown) extending in the vehicle width direction.

Below the main pipe 4, the engine 1 is provided.
0 is suspended. The engine 10 is supported by being bolted to the engine supporter 5 and the center plate 6. In addition, 11 is a radiator and 12 is an exhaust muffler. A fuel tank 13 is provided on the main pipe 4.
The seating seat 14 located at the rear of the fuel tank 13 is mounted on the seat rail 7.

A front fork 16 supporting a front wheel 15 is pivotally attached to the head pipe 3 together with a handle bar 17 so as to be rotatable left and right. On the other hand, a swing arm 19 extending rearward is pivotally attached to a pivot shaft 18 provided in the center plate 6 in the vehicle width direction so as to be vertically rotatable, and a rear wheel 20 is axially supported at a free end of the swing arm 19. ing. The rear wheel 20 is driven by the engine 10 via a chain 21.

The rear end of the swing arm 19 is provided with a rear wheel suspension device 23 according to the present invention. FIG. 2 is a left side view showing the detailed structure of the rear wheel suspension device 23,
FIG. 3 shows an embodiment of the present invention.
It is the sectional view expanded along the I line. In addition, FIG.
FIG. 4 is a sectional view developed along line IV-IV in FIG.

As shown in FIG. 2, the swing arm 19 is formed by connecting a pair of left and right arm members 24, 24 sandwiching the rear wheel 20 by a bridge member 25, and has a substantially H-shaped planar shape.

The rear wheel suspension device 23 is a device in which a restoring mechanism 26 using a torsion bar and a buffer mechanism 27 using a rotary damper are combined. First, the configuration of the restoration mechanism 26 will be described.

A torsion bar bracket 29 extending in the vehicle width direction is fixed to the lowermost portion between the left and right center plates 6 and 6 by welding or the like. The torsion bar bracket 29 is provided with three supporting arms 30, 31, 32 protruding from the supporting arm 30, 31, 32.
A torsion bar 33 is installed so as to be parallel to the pivot shaft 18.

The central portion of the torsion bar 33 is fixed to the vehicle body frame 2 by fitting the central support arm 31 with a spline 34 or the like. Further, the journal portion 3 is provided near the left and right ends of the torsion bar 33.
5, 35 are formed, and these journal parts 35, 35 are formed.
Bearings 3 on the left and right support arms 30 and 32, respectively.
Since the torsion bar 33 is supported via the rollers 6, 36, both ends of the torsion bar 33 can be twisted with respect to the center within its elastic range. Both ends of the torsion bar 33 project laterally from the left and right support arms 30 and 32, and splines 37 and 37 are formed on the projecting portions.

Torque transmission means 39 is provided between both ends of the torsion bar 33 having the splines 37, 37 and the left and right sides of the swing arm 19. The torque transmission means 39 twists both ends of the torsion bar 33 in accordance with the rotation of the swing arm 19, and a pair of left and right torque arms 40, 40 spline-coupled to both ends of the torsion bar 33 in a rotationally integrated manner.
And a pair of left and right torque rods 41, 41, one end of which is pivotally attached to the torque arms 40, 40, and the swing arm 1.
9, a pair of left and right torque brackets 42, 42 fixed to the lower surfaces of the bridge members 24, 24 for pivotally attaching the other ends of the torque rods 41, 41.

The torque arms 40, 40 are fitted to the splines 37, 37 of the torsion bar 33 in a posture substantially parallel to the swing arm 19, and the bolt 4
It is fastened to the torsion bar 33 by 3. Further, the torque rods 41, 41 extend substantially at right angles from the lower surface of the swing arm 19 and are connected to the torque arms 40, 40. The bolts 44 are respectively provided between the torque arms 40, 40 and the torque rods 41, 41 and between the torque rods 41, 41 and the torque brackets 42, 42.
It is rotatably connected by such means.

Next, the buffer mechanism 27 will be described.

As shown in FIGS. 2 and 4, a pair of left and right damper stays 4 are provided inside the left and right center plates 6 and 6.
6, 46 are fixed by bolts 47 and the like, and a rotary damper 48 is supported between the damper stays 46, 46 in parallel with the pivot shaft 18 and the torsion bar 33.

The rotary damper 48 includes a damper shaft 49 fixed to the damper stays 46, 46 by spline coupling, and a cylinder rotatably supported on the outside of the damper shaft 49 via bearings 50, 50. And a damper body 51 in the shape of a circle.

FIG. 5 is a sectional view taken along line VV of FIG.
2 shows a conceptual internal structure of the rotary damper 48. An oil chamber 52 is formed in the damper body 51, and oil is filled in the oil chamber 52.

On the inner wall of the damper body 51, a movable partition plate 53 extending toward the damper shaft 49 is provided, for example, 4
The sheets are projected at equal angular intervals. A gap 54 is formed between the free ends of the movable partition plates 53 and the peripheral surface of the damper shaft 49.

On the other hand, on the peripheral surface of the damper shaft 49, fixed partition plates 55 alternately sandwiched between the movable partition plates 53 are radially provided. A gap 56 is formed between the free ends of these fixed partition plates 55 and the inner wall of the damper body 51.

A bracket 57 is projectingly provided on the outer peripheral surface of the damper body 51. A bracket 58 is provided at the center of the lower surface of the bridge member 25 provided on the swing arm 19, and the brackets 57, 5 are provided.
The eight are connected by a link 59. Here, a bolt 60 is provided between the brackets 57, 58 and the link 59.
It is rotatably connected using such as.

Rear wheel suspension device 23 constructed as described above
Works as follows.

When the rear wheel 20 moves up and down due to the unevenness of the road surface and the swing arm 19 rotates about the pivot shaft 18 while the motorcycle 1 is running, the swing torque of the swing arm 19 is left and right. It is evenly transmitted to both ends of the torsion bar 33 by the rods 41, 41 and the torque arms 40, 40. As described above, the central portion of the torsion bar 33 is fixed to the vehicle body frame 2, and both end portions of the torsion bar 33 are supported so as to be twistable within the elastic range with respect to the central portion. When transmitted to both ends of the bar 33, both ends of the torsion bar 33 are twisted in the same direction with respect to the center.

When the torsion of the torsion bar 33 is restored to the torsion at both ends, the restoring torque is evenly applied to the left and right sides of the swing arm 19 via the torque arms 40, 40 and the torque rods 41, 41. The rotation of the swing arm 19 is restored.

The swing arm 19 is rotated by a damper body 51 of the rotary damper 48 via a link 59.
Then, the damper body 51 is rotated around the damper shaft 49. As a result, the movable partition plate 53 provided on the damper body 51 side rotates between the fixed partition plates 55 provided on the damper shaft 49 side, and the oil chamber 52
The oil inside is made to flow between the partition plates 53 and 55.
Then, the flow resistance when the oil passes through the gaps 54 and 56 becomes a damping force against the rotation of the damper body 51,
This damping force damps a sudden turning shock of the swing arm 19.

In this way, the rotation of the swing arm 19 when the motorcycle 1 is traveling is restored and buffered, and a good ride comfort is provided.

The rear wheel suspension device 23 configured as described above
Since the restoration mechanism 26 using the torsion bar 33 and the buffer mechanism 27 using the rotary damper 48 can be made compact and lightweight, and the entire device can be installed below the vehicle body, The vehicle weight of the two-wheeled vehicle 1 can be reduced and the center of gravity can be lowered.

Then, according to the present invention, the swing arm 1
Since the restoring torque of the torsion bar 33 twisted by the rotation of 9 is evenly applied to the left and right sides of the swing arm 19, the swing arm 19 is not unduly twisted, and the swing arm 19 rotates. Is very smooth.

Therefore, it is not necessary to reinforce the swing arm 19 as a countermeasure against twisting, so that the vehicle weight can be further reduced and the cost can be reduced.

The buffer mechanism 27 does not necessarily need to use the rotary damper 48, but may use, for example, a general extendable oil damper.

[0041]

As described above, in the rear wheel suspension system for a motorcycle according to the present invention, the swing arm extending rearward is rotatably pivoted on the pivot shaft provided in the vehicle body frame in the vehicle width direction. In a two-wheeled motor vehicle, in which a rear wheel is pivotally supported by a free end of the swing arm, a torsion bar parallel to the pivot axis is provided on a vehicle body frame, and a central portion of the torsion bar is fixed to the vehicle body frame. on the other hand,
Both ends of the torsion bar are supported by the vehicle body frame so that they can be twisted within the elastic range with respect to the center part, and between the both ends of the torsion bar and the left and right sides of the swing arm, depending on the rotation of the swing arm. The torque transmitting means for twisting both ends of the torsion bar is provided.

Therefore, the restoring torque of the torsion bar twisted by the swing arm is evenly applied to the left and right sides of the swing arm, and the swing arm is prevented from being excessively twisted, so that the swing arm can be pivoted extremely. It will be smooth.

Since it is not necessary to reinforce the swing arm to prevent it from being twisted, the swing arm can be made lighter, and the use of a lightweight torsion bar contributes to the reduction of the vehicle weight of the motorcycle. can do.

[Brief description of drawings]

FIG. 1 is a left side view of a motorcycle to which the present invention is applied.

FIG. 2 is a left side view showing the detailed structure of the rear wheel suspension device.

FIG. 3 shows an embodiment of the present invention and is shown in FIG.
Sectional view developed along the line III.

FIG. 4 is a sectional view developed along the line IV-IV in FIG.

5 is a cross-sectional view taken along the line VV of FIG.

[Explanation of symbols]

 1 Motorcycle 2 Body Frame 18 Hippot Shaft 19 Swing Arm 20 Rear Wheel 23 Rear Wheel Suspension Device 33 Torsion Bar 34, 37 Spline 35 Journal Part 36 Bearing 39 Torque Transmission Means 40 Torque Arm 41 Torque Rod 42 Torque Bracket 48 Rotary Damper

Claims (1)

[Claims] 1. A two-wheel automatic vehicle in which a swing arm extending rearward is rotatably and pivotally attached to a pivot shaft provided in a vehicle body frame in a vehicle width direction, and a rear wheel is pivotally supported at a free end of the swing arm. In a vehicle, a torsion bar parallel to the pivot axis is provided on the body frame, and the center portion of the torsion bar is fixed to the body frame, while both ends of the torsion bar can be twisted with respect to the center portion within an elastic range. And a torque transmitting means for supporting both ends of the torsion bar according to the rotation of the swing arm between the both ends of the torsion bar and the left and right sides of the swing arm. Rear wheel suspension system for motorcycles.