JPH0144394Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a rear wheel steering device for a front wheel drive vehicle or the like.

Generally, front-wheel drive vehicles have the problem of a large turning radius, and to overcome this problem, some vehicles have been designed to allow the rear wheels to be steered.

Such a rear wheel steering device is configured to use a hydraulically operated steering actuator to steer the rear wheels in accordance with the amount of steering of the front wheels and the vehicle speed. By the way, in such a rear wheel steering device, when driving at high speed, etc., it is necessary to maintain the rear wheels in a neutral state and prohibit steering operation, that is, to lock them in the neutral position. It has a built-in locking mechanism. At low speeds, the lock mechanism is released and the hydraulic pressure supplied to the steering actuator is controlled in response to the steering operation of the front wheels to steer the rear wheels. Further, when the vehicle is running at high speed, the locking mechanism locks the rear wheels in a neutral position and also hydraulically locks the steering actuator itself to maintain the rear wheels in a neutral position.

By the way, such a device requires two systems of hydraulic control mechanisms, one for steering and one for locking, which makes the structure complicated and, if the locking mechanism is in the locked state, if steering hydraulic pressure is supplied, this There was a problem where an excessive load was applied to the steering actuator.

The present invention was developed based on the above circumstances, and its purpose is to have a simple structure and to supply hydraulic pressure for steering when the rear wheel steering inhibition mechanism is in a steering inhibited state. The object of the present invention is to provide a rear wheel steering device without any friction.

That is, the present invention includes a hydraulic rear wheel steering actuator that steers the rear wheels, and a rear wheel steering inhibiting means that prohibits steering of the rear wheels by applying a biasing force. A first control valve is provided for controlling hydraulic pressure for canceling the inhibition of the steering inhibiting means, and a second control valve is provided for controlling the hydraulic pressure supplied to the rear wheel steering actuator, and the second control valve is the first above
The hydraulic pressure from the first control valve is used as pilot pressure, and the hydraulic pressure for steering is supplied to the rear wheel steering actuator only when the hydraulic pressure for canceling the prohibition of rear wheel steering is supplied from this first control valve. It is something to do.

Therefore, the sequence of the hydraulic pressure supplied to the rear wheel steering inhibiting means and the rear wheel steering actuator is reliably controlled by the first control valve and the second control valve, and the hydraulic pressure is controlled by the first control valve and the second control valve. It requires only one system, has a simple structure, and is highly reliable and safe.

An embodiment of the present invention will be described below with reference to the drawings. That is, 1 in the figure is an axle beam, and this axle beam 1 is supported by trailing rods 2, 2. The front ends of these trailing rods 2, 2 are rotatably attached to the vehicle body 3. Further, rotary type rear wheel steering actuators 4, 4 are attached to both ends of the axle beam 1, and king pins 5, 5 are rotatably supported on these steering actuators 4, 4. . Knuckles 6, 6 are attached to these king pins 5, 5, and rear wheels 7, 7 are attached to these knuckles 6, 6. The steering actuators 4, 4
rotates the king pins 5, 5, and rotates the rear wheels 7,
It is configured to perform 7 steering operations.

The above-mentioned steering actuators 4, 4 are constructed as shown in FIG. That is, 41 in the figure is its housing, and this housing 41 is attached to the axle beam 1 described above. Inside this housing 41 is a rotor 4.
2 is accommodated. In addition, this housing 41
Stators 43, 43 are fixed inside, and by supplying hydraulic pressure between these stators 43, 43 and rotor 42, this rotor 42 is rotated, and the rear wheels 7, 7 are steered. It is configured. Further, within the steering actuators 4, 4, there is provided a rear wheel steering inhibiting means for inhibiting steering of the rear wheels and maintaining the rear wheels in a neutral state. That is,
This housing 41 is slidably provided with lock pins 44, 44 for inhibiting steering of the rear wheels. These lock pins 44, 44 move forward by the biasing force of springs 45, 45 and fit into the lock recesses of the rotor 42, locking the rotor 42 in the neutral state and bringing the rear wheels 7, 7 into the neutral position. Configured to lock. Further, these lock pins 44, 44 are configured to move backward against the biasing force of springs 45, 45 by hydraulic pressure supplied to the rotor 42 side, and release the lock.

Further, in the figure, 10 and 10 are front wheels, 11 is a power steering mechanism for these front wheels 10 and 10, and 12 is a steering wheel. The steering amount of the front wheels 10, 10 is detected by a steering detector 13, and this signal is sent to a steering controller 15. A vehicle speed detector 14 is configured to detect the speed of the vehicle and send its signal to the steering controller 15. Based on these signals, the steering controller 15 locks the rear wheels 7, 7 in neutral when the speed is above a predetermined speed, and locks the rear wheels 7, 7 in neutral when the speed is below a predetermined speed. 7, 7 as front wheel 1
The steering wheel is configured to output a signal to indicate steering in response to steering of 0 and 10.

Further, 18 is a hydraulic pump as a hydraulic pressure generating means, and 20 is a reservoir. This hydraulic pump 18 is configured to be driven by an engine 19. The hydraulic pressure supplied from the hydraulic pump 18 is sent to the power cylinder 31 via the pilot valve mechanism 32 of the power steering mechanism 11, and the piston 33 and piston rod 3
1 to steer the front wheels 10, 10. The hydraulic pressure supplied from this pilot valve mechanism 32 is applied to the rotor 4 of the steering actuator 4 through the second control valve 17.
2 and stators 43, 43, and is configured to steer the rear wheels 7, 7. Also,
The hydraulic pressure supplied from the hydraulic pump 18 is configured to be supplied between the lock pins 44, 44 and the rotor 42 via the first control valve 16. The first control valve 16 is actuated by a signal from the steering controller 15, and for example, when the vehicle speed is higher than a predetermined speed, the lock pin 44,
44 and the rotor to the return side, and the lock pins 44, 44 are connected by springs 45, 45.
When the vehicle speed is lower than a predetermined speed, hydraulic pressure is supplied between the lock pins 44, 44 and the rotor 42 to lock the lock pins 44, 4.
4 and releases the rear wheel hydraulic prohibition state, that is, the lock. The hydraulic pressure supplied from this first control 16 is then applied to the second control 16.
control valve 17, and this second control valve 17
is configured to operate. When hydraulic pressure is supplied from the first control valve 16, that is, when the lock is released, this second control valve 17 supplies hydraulic pressure from the pilot valve mechanism 32 to the steering actuators 4, 4 to control them. When the first control valve 16 is in communication with the return side, that is, in the locked state, the pilot valve mechanism 3 is activated.
The hydraulic pressure from 2 is cut off, and the steering actuator 4,
4 is configured to be inoperable.

As described above, in the present invention, the second control valve is operated by the hydraulic pressure supplied from the first control valve, and only when hydraulic pressure is supplied so that the rear wheel steering inhibition mechanism is released from inhibition. Since the structure is configured to supply hydraulic pressure for steering, the hydraulic system is simple and the structure is simple, and the hydraulic pressure for steering can be supplied when the rear wheel steering prohibition mechanism is in the steering prohibited state. It has great effects, such as being able to reliably prevent such problems, being highly reliable, and highly safe.

[Brief explanation of the drawing]

The figures show one embodiment of the present invention, with FIG. 1 being a schematic diagram of the overall configuration, and FIG. 2 being a diagram of the configuration of the main parts. 4... Steering actuator, 7... Rear wheel, 11
... Power steering mechanism, 15 ... Steering controller, 16 ... First control valve, 17 ... Second control valve, 18 ... Hydraulic pump, 42 ... Rotor, 44
...Lock pin.

Claims (1)

[Scope of utility model registration request] A hydraulic rear wheel steering actuator is provided to operate in response to the hydraulic pressure supplied from the hydraulic pressure generating means and to steer the rear wheels. , a rear wheel steering device which is biased to inhibit steering of the rear wheels and operates against the biasing force when receiving hydraulic pressure to release the prohibited state of steering the rear wheels; a first control valve that controls the supply of release hydraulic pressure to the rear wheel steering inhibiting means; and a first control valve that is provided between the hydraulic pressure generating means and the rear wheel steering actuator; A first control valve is configured to cut off communication between the two and to operate by receiving the release hydraulic pressure supplied from the first control valve as pilot pressure to communicate the hydraulic pressure generating means and the rear wheel steering actuator. 1. A rear wheel steering device comprising: 2 control valves.