JPH07144522A - Rear side rear axle holding device for two rear axle vehicle - Google Patents

Abstract

PURPOSE:To provide a rear side rear axle holding device of simple constitution preventing reverse steering at the time of moving backward without spoiling self-steering function. CONSTITUTION:A rear side rear axle holding device for a two rear axle vehicle is provided with a gear position sensor 16 for outputting a signal corresponding to the proceeding direction of the vehicle, an expansion means 14 for changing the length of a torque rod 13 for holding a rear side rear axle 8, and a controller 15 for actuating the expansion means 14 on the basis of the output of the gear position sensor 16 so as to variably control the caster angle of the rear side rear axle 8. As a result, the caster angle of the rear side rear axle 8 always has the positive value in relation to the proceeding direction whichever forward/ backward direction the vehicle moves.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear-rear-shaft holding device for a rear two-axle vehicle, and more particularly to a rear-rear shaft holding device held by a vertical torque rod.

[0002]

2. Description of the Related Art As a conventional holding device of this type, as shown in, for example, Japanese Utility Model Laid-Open No. 62-52567, the length of a torque rod for holding a rear and rear axle is responsive to an operating angle of a steering wheel. There is a system in which the rear and rear axles are turned together with the axles to be steered.

As described above, in order to steer the rear-rear axle in the direction of self-steering, the rear-rear axle is also given a positive caster angle with respect to the forward direction. Therefore, when a vehicle equipped with such a holding device is moved backward, the caster angle becomes negative and the vehicle is steered in the opposite direction. Therefore, conventionally, a lock mechanism for fixing the rear and rear axles is provided and reverse steering occurs when the vehicle is retracted. There was a need to prevent that.

When the lock mechanism is provided in this way, the structure of the holding device becomes complicated and the weight increases. Further, when the lock mechanism is operated to prevent reverse steering, the self-steering function at the time of reverse travel is lost, the minimum turning radius is increased, or the uneven wear of the tire cannot be suppressed.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a rear-rear-shaft retaining device having a simple structure capable of preventing reverse steering when retreating without impairing the self-steering function. Is an issue.

[0006]

To solve the above problems, the present invention is provided with a gear position sensor which outputs a signal corresponding to the traveling direction of a vehicle. Further, a controller for variably controlling the caster angle of the rear-rear shaft by operating the expandable unit based on the output of the expansion-contraction unit for changing the length of the torque rod holding the rear-rear shaft and the gear position sensor is provided. Is characterized by.

[0007]

For example, when the upper torque rod is provided with the expansion / contraction means, the expansion / contraction means is extended to make the upper torque rod longer than the lower torque rod, whereby a positive caster angle with respect to the forward direction is obtained. Then, when the expansion / contraction means is operated to be shortened to make the upper torque rod shorter than the lower torque rod, a negative caster angle with respect to the forward direction is obtained. Further, the gear position sensor outputs a signal according to the traveling direction of the vehicle.

When the vehicle is moving forward, a forward signal is output from the gear position sensor and a shortening signal is supplied from the controller to the expansion / contraction means, so that the caster angle of the rear rear axle is positive with respect to the forward direction. Becomes the value of. Also, when the vehicle moves backward and the reverse signal is output from the gear position sensor, the expansion signal is output from the controller to the expansion / contraction means, so the caster angle of the rear-rear axle becomes a negative value with respect to the front. Therefore, the value is positive with respect to the rear, which is the traveling direction of the vehicle.

Therefore, regardless of whether the vehicle is moving forward or backward, the caster angle of the rear-rear axle always has a positive value with respect to the traveling direction so that the rear-rear axle self-steers in a predetermined direction. The minimum turning radius of the rear two-axle can be reduced and uneven wear of the tire can be prevented. Further, it is not necessary to provide an actuator or a lock mechanism for forcibly turning the rear-rear shaft, and thus the weight of the rear-rear shaft holding device can be reduced and the structure of the holding device can be simplified.

[0010]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a side view showing an embodiment of a rear-rear-shaft retaining device for a rear two-axle vehicle according to the present invention, and FIG. 2 is an enlarged side view of a torque rod also having a torque expansion / contraction means.

In these figures, a trunnion bracket 3 having a trunnion shaft 2 is attached to a frame 1 of a two-axle vehicle after mounting a cab (not shown) on the left end of the figures, and the trunnion shaft 2 is attached to the trunnion shaft 2. The leaf spring 5 on the spring seat 4 and the U bolt 6
It is fixed by tightening with. Further, the rear front shaft 7 is brought into contact with the lower surface of the front end portion of the leaf spring 5, and the rear rear shaft 8 is brought into contact with the lower surface of the rear end portion of the leaf spring 5.

The rear front shaft 7 and the rear rear shaft 8 and the trunnion bracket 3 are connected to the lower torque rods 9 and 10, respectively.
And the front and rear shafts 7 and 8 and the cross member 11 fixed to the frame 1 via the upper torque rods 12 and 13, the torque rods 9, 10 and 12, At 13, the rear front shaft 7 and the rear rear shaft 8 are held respectively. It should be noted that, by interposing rubber bushes (not shown) in the joint portions at the end portions of the torque rods 9, 10, 11, 12 respectively, similarly to the conventional art, the inclination of the rear front shaft 7 and the rear rear shaft 8 is allowed. There is.

The length of the upper torque rod 13 can be changed by providing the expanding / contracting means 14 at the intermediate portion of the upper torque rod 13 for connecting the rear rear shaft 8 and the cross member 11. That is, the front pipe 13a in which the upper torque rod 13 is connected to the cross member 11 is connected.
And the rear pipe 13b connected to the rear rear shaft 8 are divided and formed, and then the right end screw is provided at the rear end of the front pipe 13a and the left end screw is provided at the front end of the rear pipe 13b.
3a and 13b are connected to each other via an expansion / contraction means 14.

The expansion / contraction means 14 is a controller 15
It has a motor 14a which is controlled to rotate forward and backward in response to a signal output from the motor. Then, the gear 1 is attached to the motor 14a.
The right screw formed on one end of the threaded rod 14c interlocked via 4b is screwed into the screw hole of the front pipe 13a, and the left screw formed on the other end of the threaded rod 14c is attached to the rear pipe 1.
It is screwed into the screw hole of 3b.

Therefore, when the motor 14a is rotated in the normal and reverse directions to drive the screw rod 14c through the gear 14b in the normal and reverse directions,
The screwing depth of the screw rod 14c into both the pipes 13a and 13b changes. Then, since the front pipe 13a and the rear pipe 13b move toward and away from each other, the upper torque rod 13 expands and contracts, and the caster angle of the rear rear shaft 8 changes.

The controller 15 is connected to a gear position sensor 16 which outputs a signal in response to the traveling direction of the vehicle and a vehicle speed sensor 17 which outputs a signal in response to the traveling speed of the vehicle. Further, the controller 15 uses the signals output from both the sensors 16 and 17 to drive the motor 14a.
It is designed to optimally control the rotation direction and the rotation amount of the.

In the holding device for the rear and rear axles of the rear two-axle vehicle configured as described above, when it is determined that the vehicle is moving forward based on the signal supplied from the gear position sensor 16, the controller 15 A normal rotation signal is output. When the normal rotation signal is output from the controller 15, the motor 14
Since a rotates in the normal direction to rotate the screw rod 14c in the normal direction, the screwing depth of the screw rod 14c into the pipes 13a and 13b becomes small. Then, the upper torque rod 13 becomes longer and the straight line connecting the rear end of the lower torque rod 10 of the rear rear shaft 8 and the rear end of the upper torque rod 13 moves to the position shown by the dashed line in FIG. The caster angle of the rear shaft 8 has a positive value in the forward direction.

When it is determined that the vehicle is moving backward based on the signal supplied from the gear position sensor 16,
A reverse rotation signal is supplied from the controller 15 to the motor 14a. Then, the motor 14a rotates in the reverse direction to rotate the screw rod 14c in the reverse direction, so that the screw rod 14c is screwed into the pipes 13a and 13b in a large depth. Therefore, in this case, the upper torque rod 13 becomes shorter and the straight line connecting the rear end of the lower torque rod 10 of the rear rear shaft 8 and the rear end of the upper torque rod 13 moves to the position shown by the chain double-dashed line in FIG. Therefore, the caster angle of the rear rear shaft 8 has a negative value in the front direction, but has a positive value in the traveling direction (rear direction) of the vehicle.

That is, a positive caster angle is given to the forward direction when the vehicle is moving forward, and a negative caster angle is given to the forward direction when the vehicle is moving backward. For this reason, the caster angle of the rear-rear axle 8 always has a positive value with respect to the traveling direction regardless of whether the vehicle travels in the front-rear direction. Therefore, the rear-rear axle 8 self-steers in a predetermined direction. To be done.

Therefore, the minimum turning radius of the rear two-axle can be reduced and uneven wear of the tire can be prevented. Further, since it is not necessary to provide an actuator or a lock mechanism for forcibly turning the rear / rear shaft 8, the holding device for the rear / rear shaft 8 can be made lightweight and the structure of the holding device can be simplified. .

In the embodiment, the caster angle is changed in response to the vehicle speed signal supplied from the vehicle speed sensor 17 so as to improve the maneuverability of the vehicle. However, the caster angle is not always required in response to the vehicle speed. There is no need to change.
Further, in the embodiment, the caster angle of the rear rear shaft 8 is changed by changing the length of the upper torque rod 13, but the lower torque rod 11 is made variable and the caster angle of the rear rear shaft 8 is changed. You can also let it.

Further, in the embodiment, the expansion / contraction means 14 is composed of the motor 14a, the screw rod 14c, etc.
Although the length of the torque rod can be prevented from being changed accidentally due to a reaction force or the like, the structure of the expansion / contraction means is arbitrary as long as the length of the torque rod can be changed. The intended purpose can also be achieved by incorporating another type of expansion / contraction means typified by a cylinder or the like into the torque rod.

[0023]

As is apparent from the above description, according to the present invention, there is no need to provide an actuator for steering the rear-rear axle or a lock mechanism for preventing reverse-steer of the rear-rear axle. The shaft holding device can be made lightweight and simple. In addition, since a positive caster angle is given to the rear-rear axle not only when moving forward but also when traveling backward, reverse steer can be prevented when traveling backward without impairing the self-steering function of the rear-rear axle. In addition, the minimum turning radius of the rear two-axle can be reduced and uneven wear of the tire can be reliably prevented.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of a rear-rear-shaft retaining device for a rear two-axle vehicle according to the present invention.

FIG. 2 is an enlarged side view of a torque rod including the expansion / contraction means shown in FIG.

[Explanation of symbols]

 1 Frame 2 Trunnion Shaft 3 Trunnion Bracket 4 Spring Seat 5 Leaf Spring 6 U Bolt 7 Rear Front Axis 8 Rear Rear Axis 9, 10 Lower Torque Rod 11 Cross Member 12, 13 Upper Torque Rod 13a Front Pipe 13b Rear Pipe 14 Stretching Means 14a Motor 14b Gear 14c Screw rod 15 Controller 16 Gear position sensor 17 Vehicle speed sensor

Claims (1)

[Claims] 1. A gear position sensor that outputs a signal corresponding to a traveling direction of a vehicle and a length of the torque rod are changed in a rear two-axle vehicle having rear rear axles held by upper and lower torque rods. A rear-rear-shaft retaining device for a rear two-axle vehicle, comprising a retractable means and a controller for operating the retractable means based on the output of the gear position sensor to variably control the caster angle of the rear-rear axle.