JPH056225Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a rear wheel two-axis steering device for a vehicle.

(Prior technology) As a steering device for a vehicle with two rear axles such as a large truck, the rear axle of the two rear axles is used as the front axle in order to prevent the rear wheels from side slipping when cornering at high speed. A system in which the wheels are steered in the same direction has been proposed (Japanese Utility Model Publication No. 100062/1983).

(Problem that the invention aims to solve) By the way, in this case, only the rear axle is steered in the same direction as the front wheels during high-speed cornering, so depending on the vehicle speed, force may be applied to the rear wheels. ,
There was also concern that the car would tend to understeer on roads with a low coefficient of friction.

Therefore, it is conceivable to steer not only the rear axle but also the two rear wheel axles in the same direction as the front wheels during high-speed cornering.

However, in such vehicles, a trunnion type suspension is often adopted as a suspension system for the two rear wheels, and in that case, due to the structure of the suspension, it is not possible to make the two rear wheels steerable. There was a problem in that the steering mechanism became complicated.

The object of this invention is to enable two-axis rear wheel steering in such a vehicle with a relatively simple configuration.

(Means for solving the problem) Therefore, this invention is based on a vehicle in which two rear wheels are suspended via a trunnion type suspension, and a plate is attached to the center of the trunnion shaft so as to be freely rotatable via a vertical axis. The rear front axle and the rear axle are connected to this plate via torque rods, and an actuator is provided that rotates the plate about a vertical axis to integrally steer the two rear wheel axles.

(Function) The plate is driven by the actuator to rotate about a vertical axis with respect to the trunnion shaft, and integrally steers the rear-front shaft and the rear-rear shaft, which are connected to the trunnion shaft via a torque rod.

(Example) In Figs. 1 and 2, 1 is a side rail of the vehicle body frame, 3 is a trunnion shaft rotatably supported on the side rail 1 via a trunnion bracket 2, and 4 is attached to the rear and front axle 5 at one end. , the other end of which is suspended from the rear axle 6, and the leaf spring 4 is connected at the center to a spring seat 7A which is pivotally supported by the trunnion shaft 3 by a U-bolt 7.

A pin 8 (vertical shaft) projecting downward is integrally formed on the trunnion shaft 3 on the vehicle centerline, and a plate 9 is rotatably attached via this pin 8.

The plate 9 is attached to the rear-front shaft 5 at both ends (symmetrical positions) via lower torque clots 10A and 10B.
Similarly, it is connected to the rear axle 6 via the lower torque rods 10C and 10D, and the rear axle 5 and the rear axle 6 are integrally steered in the same direction by rotation of the plate 9 about the pin 8. ing. Incidentally, the rear front axle 5 and the rear axle 6 are connected to a cross member 12 of the vehicle body frame on the center line of the vehicle via powertrain clots 11A and 11B.

Hydraulic cylinders 13A and 13B act as actuators for pivoting the plate 9 (hydraulic cylinders 13A and 13B are arranged at symmetrical positions across the vehicle center line), and each hydraulic cylinder 13A
and 13B each have a trunnion shaft 3 at the base.
On the side, the piston rod tip is connected to plate 9.

These hydraulic cylinders 13A and 13B are connected to the reservoir tank 15 via control valves 14A and 14B, respectively, and expand and contract by hydraulic pressure from the supply pump 16 as the control valves 14A and 14B are switched.

Valve 1 controls the expansion and contraction of hydraulic cylinders 13A and 13B.
The control unit 1 consisting of a microcomputer is controlled via 4A and 14B.
7, the control unit 17 causes the two rear wheel axles 5 and 6 to move in the opposite direction to the front wheels (countersteer condition) when steering at low speeds, and to move the two rear axles 5 and 6 to the front wheels when steering at high speeds. The steering wheel is controlled to be steered by a predetermined angle in the same direction (club steer state).

In addition, 18 is a steering angle sensor that detects the steering direction and steering angle of a steering wheel (not shown), 19 is a vehicle speed sensor that detects vehicle speed, and 20 is a hydraulic cylinder 1.
A stroke position sensor that detects the stroke positions of 3A and 13B is shown.

3A and 3B are flowcharts illustrating the control operation of the control unit 17.
When the steering angle of the steering wheel exceeds a predetermined angle in step 102, the process moves to step 106 or step 110 when driving at high speed based on the steering direction and vehicle speed, and the two rear wheel axles are set in the same direction as the steering direction, or when driving at low speed. Proceeding to step 107 or 111, each hydraulic cylinder is operated to steer the two rear wheel axles by a predetermined angle in a direction opposite to the steering direction.

Then, in step 113, when the steering angle of the steering wheel becomes less than a predetermined value, each hydraulic cylinder is returned to the neutral position, that is, the two rear wheel axles are returned to the straight-ahead state.

Therefore, when steering at high speed, the rear wheels 2 axles 5
Since the wheels 6 and 6 are steered in the same direction as the front wheels, lateral slip on the rear wheels side is effectively suppressed, improving steering stability during high-speed cornering.

In addition, when maneuvering at low speeds, the rear wheels 2 axles 5
Since the wheels 6 and 6 are steered in the opposite direction to the front wheels, the turning radius of the vehicle becomes smaller. In the present invention, the plate 9 connecting the rear front axle 5 and the rear axle 6 through the torque rods 10A to 10D is rotated, so that the steering angle of the rear wheels as a whole can be set sufficiently large. Such anti-phase steering allows the minimum turning radius of the vehicle to be made extremely small.

Furthermore, the hydraulic cylinder 1 which is an actuator
3A and 13B are placed above the plate 9, which provides sufficient ground clearance and improves performance against obstacles while driving.The plate 9 also functions as a cover to protect the actuator from mud splashing while driving. It has the advantage of protecting the material and improving its durability.

(Effects of the invention) In summary, according to this invention, a plate is rotatably attached to the center of the trunnion shaft via a vertical shaft, and each of the two rear wheel axles is connected to this plate via a torque rod. We have installed an actuator that rotates the plate to integrally steer the two rear wheels, so for example, during high-speed cornering, the two rear wheels can be turned in the same direction as the front wheels to prevent side slip on the rear wheel side. is suppressed more effectively than before, further improving steering stability.

In addition, since the two rear wheel axles are integrally steered via the plate by the operation of the actuator, the structure is relatively simple, and the maximum steering angle of the two rear wheel axles can be large, especially when the phase is reversed. It is possible to significantly reduce the minimum turning radius by steering.

Furthermore, since the actuators such as hydraulic cylinders are placed above the plate, it is possible to secure a large minimum ground clearance and improve the vehicle's running performance.
It is also possible to prevent the actuators from becoming dirty due to mud splashing, etc., thereby improving the durability of the device.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an embodiment of this invention.
FIG. 2 is a view taken along arrow E, and FIGS. 3A and 3B are flowcharts for explaining the control operation of the control unit. 3...Trunion shaft, 4...Leaf spring, 5...Rear front shaft, 6...Rear rear shaft, 8...Pin, 9...Plate, 10A to 10D...Lower torque cloth, 13A, 13B...Hydraulic cylinder .

Claims (1)

[Scope of utility model registration request] In a vehicle with two rear wheels suspended via a trunnion type suspension, a plate is attached to the center of the trunnion shaft to freely rotate via a vertical axis, and the rear front and rear axles are connected to this plate through torque rods. A two-axis rear wheel steering device for a vehicle, characterized in that an actuator is provided above the plate to integrally steer the two rear wheels by rotating the plate about a vertical axis. .