JPH06344970A - Rear wheel suspension of motorcycle - Google Patents

Abstract

PURPOSE:To provide a rear wheel suspension for motorcycle capable of improving the external appearance without causing problems of extending a distance between shafts and compilcating construction by abolishing a cylinder-piston type buffer. CONSTITUTION:The front part of a motor unit combining a electric motor with a power transmitting mechanism in the inverted L-shaped form as viewed in a plane is supported vertically swingingly with a body frame and a rear wheel suspension of a motorcycle is composed to have the rear wheel shaft- supported with the rear end of the motor unit. Then, a motor case part of the motor unit is formed into a generally cylindrical form extending in the vehicle lateral direction and a bar-like bushing 18 having an elastic body 21 inserted fixedly between the inner and outer tubes 19, 20 and extending along the motor case part in the vehicle lateral direction is disposed between the motor case part and vehicle frame. The inner tube 19 and outer tube 20 are respectively fixed to the body frame and motor case part.

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 suitable for, for example, a scooter type motorcycle equipped with a unit swing type motor unit.

[0002]

2. Description of the Related Art In the conventional rear wheel suspension system for a scooter type motorcycle, generally, a front portion of an engine unit in which an engine and a power transmission mechanism are integrated is swingably supported by a vehicle body frame. A cylinder / piston type shock absorber is disposed between the rear portion and the vehicle body frame, and the rear wheel is pivotally supported by the rear end portion of the engine unit.

[0003]

However, in the above-mentioned conventional device, there is a problem in that it does not look good because the shock absorber is arranged at a position visible from the outside. In order to solve this problem, a shock absorber is placed between the rear wheel and the engine unit so as not to be seen from the outside (see Japanese Utility Model Laid-Open No. 3-88895), or placed below the footrest portion via a link mechanism. A structure (see Japanese Utility Model Laid-Open No. 3-8987) is proposed. However, in the former case, there is a problem that the distance between the axes becomes long, and in the latter case, there is a problem that the structure becomes complicated due to the necessity of the link mechanism.

The present invention has been made in view of the above-mentioned conventional circumstances, and the conventional cylinder / piston type shock absorber can be eliminated, and therefore the problems of extending the axial distance and complicating the structure do not occur. It is an object of the present invention to provide a rear wheel suspension device for a motorcycle that can improve the appearance.

[0005]

According to the present invention, a front portion of a motor unit formed by connecting an electric motor and a power transmission mechanism in a substantially Γ shape in a plan view is swingably supported by a vehicle body frame, In a rear wheel suspension system for a motorcycle in which a rear wheel is axially supported at a rear end of a motor unit, a motor case portion of the motor unit is formed into a substantially cylindrical shape extending in a vehicle width direction, and the motor case portion and the vehicle frame are formed. Between and,
An elastic body is inserted and fixed between the outer cylinders, and a rod-shaped bush extending along the motor case portion in the vehicle width direction is arranged. One of the inner cylinder and the outer cylinder is a body frame, and the other is the motor case. It is characterized by being fixed to the part.

[0006]

In the rear wheel suspension system for a motorcycle according to the present invention, when the rear wheel moves up and down, the inner and outer cylinders of the rod-shaped bush rotate relatively, which causes the elastic body to generate a twisting torque. The load acting on the rear wheel can be absorbed by this twisting torque. Therefore, according to the present invention, the conventional cylinder / piston type shock absorber is not necessary, and the rod-shaped bush is not exposed to the outside. Therefore, the external appearance can be improved without the problems of extending the axial distance and complicating the structure. improves.

Further, in the present invention, since the electric motor is adopted as the drive source, the case portion of the motor can be made substantially cylindrical and can be laterally arranged. Therefore, the bush of the bush can be provided between the motor case portion and the body frame. You can secure a space for placement. Therefore, the length of the rod-shaped bush can be freely selected, and as a result, it becomes possible to obtain the twisting torque required for rear wheel suspension. By the way, when a gasoline engine is adopted as a drive source, there is a concern that the space for disposing the bush cannot be secured because the space for disposing the cylinder body is required.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 5 are views for explaining a rear wheel suspension system of a scooter type motorcycle according to a first embodiment of the present invention, FIG. 1 is a side view of the motorcycle, FIG. 2 is a side view of a motor unit, 3 is a cross-sectional plan view of the motor unit, FIG.
FIG. 5 is a cross-sectional plan view of the rod-shaped bush portion, and FIG. 5 is a characteristic diagram for explaining the function and effect.

In the figure, reference numeral 1 denotes a scooter type motorcycle, and a body frame 2 of the scooter type motorcycle has a head pipe 2b fixed to a front end of a main pipe 2a and a pair of left and right connecting angle pipes extending in the vehicle width direction at a rear end thereof. 2c is a steel pipe underbone type in which a pair of left and right side pipes 2d extending upward are fixed to the outer ends of the square pipes 2c. A front fork 4 that pivotally supports the front wheel 3 is rotatably supported by the head pipe 2b.
A steering handle 5 is attached to the upper end of the.

The main pipe 2a of the vehicle body frame 2 is bent downward, and a foot rest 6 having a low floor is formed so as to surround the bent portion. A total of four batteries 7 are mounted on the lower side of the footrest section 6, two on the left and two on the right across the main pipe 2a.

A motor unit 8 is disposed behind the left and right side pipes 2d, 2d of the body frame 2.
The motor unit 8 is configured by integrally connecting a drive motor 9 and a power transmission mechanism 10 in a substantially Γ shape in a plan view. In the drive motor 9, a stator (stator) 11 is arranged and fixed in a motor case 9a in which a heat radiation fin is formed in a cylindrical body, and a rotor (rotor) 13 having a rare earth magnet 12 fixed thereto is fixed in the stator 11. It is also rotatably inserted and arranged. Reference numeral 14 is a radiator that radiates heat from the motor by introducing traveling wind. The rotor 13 serves as an output shaft.

The power transmission mechanism 10 includes a left case 1 and a right case 1.
The transmission 1 in a two-part transmission case consisting of 0a and 10b.
5 is accommodated and arranged, and the input shaft 15 of the transmission 15
a is connected to the rotor 13 via a transmission chain 16,
A rear wheel 17 is attached to the output shaft 15b of the transmission 15.

The motor unit 8 is swingably supported by the vehicle body frame 2 via a rod-shaped bush 18. As shown in FIG. 4, this rod-shaped bush 18
Is a left and right two-divided structure, in which a cylindrical rubber 21 is inserted and baked between an inner cylinder 19 having a bolt hole 19a having a rectangular cross section and a cylindrical outer cylinder 20. As shown in FIG. 5, when the inner cylinder 19 and the outer cylinder 20 rotate relative to each other, the rod-shaped bush 18 generates a twisting torque proportional to the rotation angle.

The left and right outer cylinders 20 are fixed to the right case 10b of the power transmission mechanism 10 and the boss portions 10c and 9b formed integrally with the motor case 9a of the drive motor 9, respectively. A through bolt 22 having a rectangular cross section is inserted into the left and right inner cylinders 19, and the through bolt 22 is fixed to a bracket 2e fixed to the connecting angle pipe 2c by a nut 22a. Further, the square-shaped locking portion 22b formed on the head of the through bolt 22 is non-rotatably locked in the square hole 2f of the bracket 2e. Thereby, the inner cylinder 1 of the rod-shaped bush 18
9 is non-rotatably fixed to the vehicle body side, and the outer cylinder 20 is adapted to rotate together with the motor unit 8.

Next, the function and effect of this embodiment will be described. For example, when the rear wheel 17 rides on the convex portion of the road surface, the motor unit 8 swings upward around the rod-shaped bush 18. Then, the inner cylinder 19 and the outer cylinder 20 relatively rotate in the rod-shaped bush 18, and a twisting torque corresponding to the rotation angle is generated (see FIG. 5), which causes the rear wheel 17 to rotate.
The thrust load to the is absorbed.

According to the rear wheel suspension system of this embodiment, the motor unit 8 is swingably supported by the vehicle body frame 2 via the rod-shaped bush 18 formed by fixing rubber between the inner and outer cylinders. The vertical movement of the rear wheel 17 can be absorbed by the twisting torque generated by the rod-shaped bush 18, and therefore,
The conventional cylinder / piston type shock absorber is unnecessary, and the rod-shaped bush 18 is not exposed to the outside. As a result, extension of the axial distance, such as when disposing the shock absorber between the rear wheel and the drive unit invisible from the outside,
Alternatively, the external appearance can be improved without causing the problem of complication of the structure as in the case where the shock absorber is arranged below the foot rest through the link mechanism.

Further, in this embodiment, since the electric motor 9 is adopted as the drive source, the motor case 9a can be made substantially cylindrical and can be arranged in the vehicle width direction. Therefore, a space for disposing the bush can be secured between the motor case 9a and the vehicle body frame 2, and a sufficient length of the rod-shaped bush 18 can be secured. As a result, it becomes possible to obtain the twisting torque required for rear wheel suspension.

FIGS. 6 and 7 are views showing a second embodiment of the present invention, in which the same reference numerals as those in FIGS. 1 to 4 designate the same or corresponding parts. The rod-shaped bush 28 of this embodiment is a so-called Nytehardt type bush, in which a rectangular bolt hole 29a is formed in the axis of the inner cylinder 29 and an inwardly concave arc surface 29 is formed in the outer surface.
b is formed. An elastic rod 31 having a circular cross section is provided between the arc surface 29b of the inner cylinder 29 and the inner surface of the outer cylinder 30.
Is intervening.

In this embodiment, when the relative rotation angle is generated between the inner cylinder 29 and the outer cylinder 30 due to the vertical movement of the rear wheel 17,
Each elastic rod 31 moves to the corner side of the outer surface of the inner cylinder 29 and is sandwiched between the elastic rod 31 and the outer cylinder 30, whereby a twisting torque as shown in FIG. 7 is generated. In this case, a so-called progressive effect is obtained in which the generated torque does not increase so much in the region where the rotation angle is small, and the generated torque sharply increases in the region where the rotation angle is large.

[0020]

As described above, according to the rear wheel suspension system for a motorcycle according to the present invention, the motor unit is swingably supported by the vehicle body frame via the rod-shaped bush that generates a twisting torque. The vertical movement of the rear wheel can be absorbed by the twisting torque of the rod-shaped bush, so that the conventional piston type shock absorber is not necessary, and the appearance can be improved without the problems of extending the shaft distance and complicating the structure. There is.

Further, in the present invention, since the electric motor is adopted as the drive source, the motor case can be formed in a substantially cylindrical shape and can be laterally arranged. Therefore, the bush in the vehicle width direction between the motor case and the body frame. It is possible to secure a space for the extension, and as a result, it is possible to secure a sufficient length of the rod-shaped bush and obtain a twisting torque required for rear wheel suspension.

[Brief description of drawings]

FIG. 1 is a side view of a scooter type motorcycle in which a rear wheel suspension device according to a first embodiment of the present invention is adopted.

FIG. 2 is a side view of the device of the first embodiment.

FIG. 3 is a cross-sectional plan view of a motor unit including the device of the first embodiment.

FIG. 4 is a cross-sectional plan view of a torsion bush portion of the first embodiment device.

FIG. 5 is a characteristic diagram showing a relationship between a rotation angle of the first embodiment apparatus and a twisting torque generated.

FIG. 6 is a sectional side view of a torsion bush according to a second embodiment of the present invention.

FIG. 7 is a characteristic diagram showing accounting of the rotation angle and the twisting torque generated in the device of the second embodiment.

[Explanation of symbols]

 1 Motorcycle 2 Body Frames 2c, 2c Left and Right Side Pipes (Frame Members) 8 Motor Unit 9 Electric Motor 9a Motor Case 10 Power Transmission Mechanism 10a, 10b Left, Right Transmission Case 17 Rear Wheel 18, 28 Torsion Bush 19, 29 Inner cylinder 20,30 Outer cylinder 21,31 Rubber, torsion rod (elastic body)

Claims (1)

[Claims] 1. A front portion of a motor unit formed by coupling an electric motor and a power transmission mechanism in a substantially Γ shape in a plan view is swingably supported by a vehicle body frame, and a rear end portion of the motor unit is rearwardly supported. In a rear wheel suspension system for a motorcycle having a wheel rotatably supported, a motor case portion of the motor unit is formed in a substantially cylindrical shape extending in a vehicle width direction, and inner and outer portions are formed between the motor case portion and the body frame. An elastic body is inserted and fixed between the cylinders, and a rod-shaped bush extending along the motor case portion in the vehicle width direction is arranged. One of the inner cylinder and the outer cylinder is a body frame, and the other is the motor case portion. Rear wheel suspension system for motorcycles, characterized in that it is fixed to.