JPH05330472A - Rear wheel steering device of motorcycle - Google Patents

Abstract

PURPOSE:To provide a rear wheel steering device of a motorcycle which can secure the high traveling stability while allowing a smooth steering of the rear wheel. CONSTITUTION:In a rear wheel steering device of a motorcycle where the rear wheel 4 is steered by supporting the rear wheel 4 in a rotatable manner around the vertical axis (X axis) relative to a rear axle 10, and rotating the rear wheel 4 around the vertical axis (Z axis) by an actuator, a stopper link 36 to regulate the rotation around the cycle body center line (X axis) of the rear wheel 4 is interposed between the rear wheel 4 and a rear arm 5. The rigidity of the rear wheel 4 around the X axis is increased by the stopper link 36, the rotation around the X axis of the cycle body is regulated and a high traveling stability is secured. Since ball joints 37, 38 are used for the stopper link 36, the stopper link 36 allows the rotation around the vertical axis (Z axis) of the rear wheel 4, and the steering of the rear wheel 4 is not obstructed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear wheel steering system for a motorcycle, in which the rear wheels are steered in conjunction with the steering of the front wheels.

[0002]

2. Description of the Related Art In a motorcycle, it is possible to steer the rear wheels by a rear wheel steering device in order to improve the running stability in the middle / high speed range or to keep the turning radius small in the low speed range. Has been.

As such a rear wheel steering device, for example, the rear wheel is supported rotatably about a vertical axis with respect to the rear axle, and the rear wheel is rotated by an actuator around the vertical axis. Those that steer are known.

By the way, in a motorcycle equipped with the above-mentioned rear wheel steering device, rotation around the vehicle body central axis (X axis) is suppressed to be small to ensure high running stability, and the vertical axis of the rear wheels ( It is desired to allow rotation around the Z axis) so that the rear wheels can be easily steered. Therefore, for that purpose, it is necessary to maintain the rigidity of the rear wheel around the vertical axis to be small and to increase the rigidity around the vehicle body axis.

[0005]

However, in the conventional rear wheel steering system, since the mechanism for increasing the rigidity of the rear wheels around the vehicle body axis is not mechanically devised, the running stability can be kept high. could not.

The present invention has been made in view of the above problems, and an object of the present invention is to rear-wheel steering a motorcycle capable of ensuring high running stability while permitting smooth steering of the rear wheels. To provide a device.

[0007]

In order to achieve the above object, the present invention supports a rear wheel so as to be rotatable about a vertical axis with respect to a rear axle, and rotates the rear wheel about a vertical axis by an actuator. In a rear wheel steering system for a motorcycle, which steers the rear wheel, a stopper link is provided between the rear wheel and a rear arm for restricting rotation of the rear wheel around a vehicle body center axis. And

[0008]

According to the present invention, since the rigidity of the rear wheel around the center axis of the vehicle body is enhanced by the stopper link, the rotation around the center axis of the vehicle body is restricted, and high running stability is ensured. If a universal joint such as a ball joint is adopted for the stopper link, the stopper link allows rotation of the rear wheel around the vertical axis (Z axis), so that steering of the rear wheel is hindered by the stopper link. It is possible to smoothly steer the rear wheels.

[0009]

An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a longitudinal sectional view of a rear wheel portion of a motorcycle equipped with a rear wheel steering device according to the present invention, FIG. 2 is a plan sectional view of a rear wheel portion of the motorcycle, and FIG. 3 is a rear view portion of the present invention. FIG. 4 is a block diagram showing the system configuration of the wheel steering device, and FIG. 4 is a side view of the motorcycle.

Referring to FIG. 4, a schematic structure of the motorcycle will be described. In the figure, reference numeral 1 is a front wheel, which is rotatably supported by a lower end portion of a front fork 2. The front wheel 1 is steered by rotating the handle 3 left and right.

Further, in the drawing, reference numeral 4 denotes a rear wheel steered together with the front wheel 1, which is rotatably supported by a rear end portion of a rear arm 5, and the front end portion of the rear arm 5 is rotated by a vehicle body frame 6. It is movably connected. In addition, in FIG.
Is an engine, 8 is a fuel tank, and 9 is a seat.

The structure of the rear wheel steering system according to the present invention will now be described with reference to FIGS. 1 and 2.

As shown in the figure, a rear axle 10 for rotatably supporting the rear wheel 4 is laterally mounted on the rear end of the bifurcated rear arm 5 extending leftward and rightward toward the rear of the vehicle body. , The king pin 11 is provided at the center of the rear axle 10 in the vehicle width direction.
Is rotatably supported by a thrust bearing 12 and a needle bearing 13 about a vertical axis (Z axis).

The rear wheel 4 has the kingpin 11
It is supported rotatably around a vertical axis (Z axis) around this. That is, as shown in FIG.
1, a cylindrical holder 14 covering a part of the rear axle 10 is bound by a nut 15, and a hub 4a of a rear wheel 4 is rotatably supported on the holder 14 via a ball bearing 16. ing. The left and right of the rear wheel 4 are divided into a drive side and a brake side, and a disc brake 17 is provided on the brake side.
Is composed of a ring-shaped disk plate 17a connected to the side end surface of the hub 4a of the rear wheel 4 and a caliper 17b connected to the outer periphery of one end of the holder 14.

On the other hand, on the drive side, the power transmission member 1
8 is rotatably supported on the rear axle 10 via a ball bearing 19, and the power transmission member 18 is engaged with another power transmission member 21 via a rubber damper 20.
The power transmission member 21 is connected to the yoke joint 22.
Is connected to the disc 4b of the rear wheel 4 via. still,
The yoke joint 22 allows rotation about the vertical axis of the rear wheel 4 (Z axis: central axis of the kingpin 11),
A joint for transmitting rotation to the rear wheel 4.

A chain sprocket 23 is connected to the outer end surface of the power transmission member 18, and the chain sprocket 23 and the output shaft end of the engine 7 (see FIG. 4) are connected to each other (not shown). An endless drive chain 24 is wound between the chain sprockets. As described above, in the present embodiment, the left and right sides of the rear wheel 4 are distributed to the drive side and the brake side, so that the chase sprocket 23 and the disc brake 17 are distributed to the left and right, and the entire body of the vehicle body is distributed. The width is narrowed and the body can be made compact. Further, with the above configuration, the braking force generated by the disc brake 17 is directly transmitted to the rear wheel 4 without passing through the rubber damper 20, so that a high brake feeling can be obtained.

By the way, as shown in FIG. 2, one of the forked rear arms 5 is provided with a servo motor 25 constituting an actuator of the rear wheel steering device, and an output shaft of the servo motor 25 is A shaft 27a of a worm gear 27 housed in the housing 26 is connected via a flexible coupling 28, and a gear 29 is bonded to the shaft 27a. Also, in the housing 26,
Potentiometer 3 that constitutes a feedback sensor
0 is stored, and a small-diameter gear 31 meshing with the gear 29 is connected to the input shaft of the potentiometer 30.

Further, a wheel gear 32 that meshes with the worm gear 27 is housed in the housing 26, and the wheel gear 32 is pivotally mounted by a vertical shaft 33 so as to be rotatable in the horizontal direction. One end of a rod 34 having an adjustable length is connected to the wheel gear 32, and the other end of the rod 34 is a tip portion of an arm 35 integrally extending from the holder 14 obliquely forward. Is linked to.

Thus, as shown in FIG. 1, in this embodiment, between the holder 14 and the rear arm 5, the rotation of the rear wheel 4 around the vehicle body center axis (X axis) is restricted. The stopper link 36 is provided. The stopper link 36 includes an inverted L-shaped link member 36a that is erected on the rear arm 5, a link member 36b that extends obliquely upward from the holder 14, and both link members 36a and 36b. The joints 37 and 38 are constituted by a rod 36c whose both ends are rotatably connected.

The system configuration of the rear wheel steering system according to the present invention will be described with reference to FIG.

In the figure, 40 is a steering mechanism including a handle 3 (see FIG. 4) for steering the front wheels 1, and 41 is a handle 3.
A steering angle sensor for detecting the steering angle of the vehicle, 42 is a low-pass filter that constitutes a low-frequency pass circuit, 43 is a vehicle speed sensor that detects the vehicle speed by counting the number of rotations of the front wheel 1, and these are CPU (arithmetic unit). It is electrically connected to 50. The CPU 50 is a system power supply 51.
Driven by.

On the other hand, 44 is a steering mechanism for steering the rear wheels 4, which comprises the king pin 11 and the holder 1.
4, worm gear 27, wheel gear 32, rod 35
And so on. The servo motor 25 that drives the steering mechanism 44 and the potentiometer 30 are electrically connected to the CPU 50.

Next, the operation of the rear wheel steering system according to the present invention will be described.

The rotational power of the engine 7 is driven by the drive chain 24.
And the power transmission member 18 via the chain sprocket 23.
Is transmitted to the rear axle 10, the rotation of the power transmission member 18 is transmitted to another power transmission member 21 via the rubber damper 20, and further to the yoke joint 22. This is transmitted to the rear wheel 4, and thereby the rear wheel 4 is rotationally driven to drive the motorcycle. The unevenness of the rotation transmitted from the engine 7 to the driving force transmission member 18 is absorbed by the rubber damper 20.

When the rider steers the steering wheel 3 to steer the front wheel 1 to the left or right while the motorcycle is traveling, the steering angle of the steering wheel 3 is detected by the steering wheel steering angle sensor 41. The detection signal is input to the CPU 50 through the low pass filter 42.
At the same time, the current vehicle speed detected by the vehicle speed sensor 43 is also input to the CPU 50.

Then, the CPU 50 calculates an optimum value of the steering angle of the rear wheels 4 from the input steering angle of the steering wheel 3 and the vehicle speed, and outputs a control signal corresponding to the calculated value to the servomotor 25.

When the servomotor 25 receives a control signal from the CPU 50 and rotates in a predetermined direction by a predetermined number of rotations, the rotation is accelerated by the gears 29 and 31 and input to the potentiometer 30. Detect the amplified rotation speed and set the value to CP
Give feedback to U50. Thus, when the rotation of the servo motor 25 is accelerated by the gears 29 and 31,
Since the sensitivity (resolution) of the potentiometer 30 is increased, the feedback control of the servomotor 25 by the CPU 50 is performed with high accuracy, and the rotation speed of the servomotor 25 is made to match the set value.

The rotation of the servo motor 25 is transmitted to the worm gear 27 via the flexible coupling 28, and the worm gear 27 is rotationally driven in a predetermined direction by a predetermined number of revolutions. Then, the wheel gear 32 meshing with the worm gear 27 rotates about the vertical shaft 33 in a predetermined direction by a predetermined angle, and the rotation of the wheel gear 32 causes the holder 14 and the rear wheel 4 to rotate via the rod 34 and the arm 35. It is converted into rotation around the Z axis (the central axis of the kingpin 11), and the rear wheel 4 is moved by a predetermined angle in a predetermined direction according to the steering angle of the front wheel 1 (turning angle of the steering wheel 3) and the vehicle speed at that time. Steered to ensure high stability when traveling in the medium and high speed range, and to keep the turning radius small when traveling in the low speed range.

Thus, in this embodiment, since the rigidity of the rear wheel 4 around the X axis is increased by the stopper link 36,
Rotation of the vehicle body around the X axis is restricted, and high running stability is ensured. Ball stoppers 37 and 38, which are universal joints, are used for the stopper link 36. Since the stopper link 36 allows the rear wheel 4 to rotate about the Z axis, steering of the rear wheel 4 is prevented. The smooth steering of the rear wheels 4 is possible without being hindered by the above.

In this embodiment, the servomotor is used as the actuator of the rear wheel steering device, but the actuator is not limited to this, and a hydraulic cylinder or the like may be used.

[0032]

As is apparent from the above description, according to the present invention, the rear wheel is rotatably supported about the vertical axis with respect to the rear axle, and the rear wheel is rotated about the vertical axis by the actuator. In a rear-wheel steering system for a motorcycle that steers the rear wheels by forcing, a stopper link that restricts rotation of the rear wheels around the vehicle body center axis is provided between the rear wheels and the rear arm. The rigidity around the center axis of the vehicle body is enhanced by the stopper link, and it is possible to obtain an effect that high running stability can be ensured while allowing smooth steering of the rear wheels.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a rear wheel portion of a motorcycle including a rear wheel steering device according to the present invention.

FIG. 2 is a plan sectional view of a rear wheel portion of a motorcycle including a rear wheel steering device according to the present invention.

FIG. 3 is a block diagram showing a system configuration of a rear wheel steering system according to the present invention.

FIG. 4 is a side view of a motorcycle including a rear wheel steering device according to the present invention.

[Explanation of symbols]

 4 Rear Wheel 5 Rear Arm 10 Rear Axle 11 King Pin 25 Servo Motor (Actuator) 36 Stopper Link

Claims (1)

[Claims] 1. A rear wheel of a motorcycle in which a rear wheel is rotatably supported around a vertical axis with respect to a rear axle and the rear wheel is steered by rotating the rear wheel by an actuator around the vertical axis. In the steering system, a rear wheel steering system for a motorcycle, wherein a stopper link is provided between the rear wheel and the rear arm for restricting rotation of the rear wheel around the vehicle body center axis.