JPH0245112Y2 - - 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.

In general, front-wheel drive vehicles have the problem of a large turning radius, and to overcome this problem, some vehicles have been made so that the rear wheels can also be steered. Such a rear wheel steering device generally includes a steering actuator that steers the rear wheels, and controls the hydraulic pressure supplied to this steering actuator from a hydraulic pump in response to the steering of the front wheels. The vehicle is configured to steer in response to the steering of the front wheels. By the way, in this type of system, the above-mentioned hydraulic pump is constantly operated, so there is a problem that there is a large loss of power and a high fuel consumption rate, and if the control valve etc. breaks down, the rear wheels may be damaged undesirably. There is a possibility that it will be manipulated.

For this reason, some vehicles are configured to stop the operation of the hydraulic pump when steering of the rear wheels is not required, depending on the traveling speed of the vehicle. However, even with this type of vehicle, the hydraulic pump is constantly operating under certain driving conditions, resulting in a large power loss and a high fuel consumption rate.

The present invention has been developed based on the above circumstances, and its purpose is to provide a rear wheel running device that has extremely little loss of power and is free from the possibility of malfunction.

That is, in the present invention, the vehicle speed is detected by the vehicle speed detection means, the steering state is detected by the steering state detection means, and based on the signals from these, the steering state is determined when the vehicle speed is below a predetermined value. In response to this, the steering control means outputs a drive signal to the control valve mechanism to steer the rear wheels, and when the vehicle speed is above a predetermined value, drives a hydraulic pump that supplies hydraulic pressure to the steering actuator. This is to stop the motor. Further, an accumulator is provided between the hydraulic pump and the steering actuator, and the pressure within the accumulator is detected by a pressure detection means. The steering control means controls the drive of the hydraulic motor so that the pressure in the accumulator is maintained at a predetermined pressure when the vehicle speed is below the predetermined value. . Therefore, when there is no possibility of steering the rear wheels, such as when driving at high speed, the motor is stopped and the hydraulic pump does not operate, so there is no wasted power and the fuel consumption rate is improved.

Furthermore, when the hydraulic pump operates at low speeds, the hydraulic pump is driven to maintain a constant pressure within the accumulator, resulting in extremely small loss of power and further improving fuel consumption. In addition, when the rear wheels do not need to be steered, such as when driving at high speeds, the hydraulic pump does not operate, so even if the pressure inside the accumulator naturally decreases due to internal leakage, this hydraulic pump will not be activated. In this respect as well, no power loss occurs.

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

In the figure, reference numeral 1 denotes an axle beam, and this axle beam 1 is supported by a vehicle body 3 via trailing rods 2, 2. Knuckles 4, 4 are rotatably attached to both ends of this axle beam 1 by king pins 5, 5, and rear wheels 6, 6 are attached to these knuckles 4, 4. These nuts 4, 4 are connected to the control rod 8, 4 by the steering actuator 9.
8, the rear wheels 6, 6 are rotated via arms 7, 7 to steer these rear wheels 6, 6.

Further, 10 and 10 are front wheels, 11 is a steering mechanism thereof, and 12 is a steering wheel. The steering amount of these front wheels 10, 10 is detected by a steering state detecting means, such as a steering detector 13, and the signal thereof is sent to a steering controller 15 of the steering controlling means. Reference numeral 14 denotes vehicle speed detection means, such as a vehicle speed detector, which 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 outputs, for example, a signal to lock the rear wheels 6, 6 in neutral when the vehicle speed is higher than a predetermined speed, and outputs a signal to lock the rear wheels 6, 6 in neutral when the vehicle speed is higher than a predetermined speed. In the following cases and when the front wheels 10, 10 are steered by a predetermined angle or more, a signal to steer the rear wheels 6, 6 in response to the steering of these front wheels 10, 10 is output. Ru. The signal from the steering controller 15 is then sent to the control valve mechanism 16. This control valve mechanism 16 controls the hydraulic pressure from the hydraulic pressure supply mechanism 17 based on the above signal and supplies it to the above-mentioned steering actuator 9 to steer the rear wheels 6, 6 or to lock them in neutral. It is configured as follows. Further, a signal from the vehicle speed detector 14 is sent to a hydraulic pressure controller 18 of the steering control means, and the hydraulic pressure controller 18 is configured to control the hydraulic pressure supply mechanism 17 based on this signal.

These mechanisms are constructed as shown in FIG. That is, the above-mentioned steering actuator 9 has a housing 20 in which a steering cylinder chamber 21 and a lock cylinder chamber 24 are formed. A piston 22 is housed within the steering cylinder chamber 21 . Note that 23 is a piston rod. Further, a lock portion 25 is formed on this piston rod 23,
This lock portion 25 is accommodated within the lock cylinder chamber 24. Lock bodies 30, 30 are accommodated in this lock cylinder chamber 24, and these lock bodies 30, 30 press the lock part 25 from both sides by hydraulic pressure, and lock this steering actuator 9 in the neutral position. It is configured as follows. Furthermore, a lock pin chamber 28 is formed in the housing 20, and a lock pin 27 is accommodated within this lock pin chamber 28. This lock pin 27 is advanced by a spring 29 and fitted into a lock groove 26 formed in the lock portion 25 to lock the lock pin, and is moved back by hydraulic pressure supplied to the lock pin chamber 28 to lock the lock pin 27. It is configured to be released.

Further, the control valve mechanism 16 is configured as follows. That is, 31 is a steering switching valve, 32
is a lock switching valve. These are operated by signals from the steering controller 15 of the steering control means described above, and the steering control valve 31 is operated by the steering actuator 9 via the pilot check valves 33, 33'.
The steering cylinder chamber 21 of the vehicle is configured to selectively supply hydraulic pressure to the steering cylinder chamber 21 of the vehicle. Further, the lock switching valve 32 is configured to supply hydraulic pressure to the lock cylinder chamber 24 and the lock pin chamber 28, or communicate these chambers with the return side, thereby locking and releasing the lock.

Further, the hydraulic pressure supply mechanism 17 is configured as follows. That is, 41 is a hydraulic pump;
4 is a reservoir, and 43 is an accumulator. The hydraulic pump 41 is configured to be driven by a motor 42. Further, an unload relief valve 45 is provided on the discharge side of the hydraulic pump 41, and when the hydraulic pressure discharged from the hydraulic pump 41 exceeds a predetermined pressure, this hydraulic pressure is automatically released to the return side. It is configured to maintain a constant pressure. On the discharge side of the hydraulic pump 41, pressure detection means such as a first pressure switch 46 and a second pressure switch 46 are provided.
7 is provided, and is configured to detect the pressure on the discharge side of this hydraulic pump 41, that is, the pressure in the accumulator 43 and the system. These first pressure switch 46 and second pressure switch 4
The signal from 7 is sent to a hydraulic controller 18 of the steering control means. Further, a speed signal from the vehicle speed detector 14 is sent to the hydraulic pressure controller 18 . The hydraulic controller 18 controls the motor 42 for driving the hydraulic pump 41 based on signals from the first pressure switch 46 and the second pressure switch 47.
The pressure inside the accumulator 43 and this hydraulic system is maintained at a predetermined pressure. Additionally, this hydraulic controller 18 is connected to a vehicle speed detector 14.
When there is no possibility that the rear wheels 6, 6 will be steered based on the signal from The motor 42 is maintained in a stopped state, and even if the pressure in the hydraulic system decreases, this motor 4
2 is configured not to start.

As described above, the present invention controls the operation of the hydraulic pump to the minimum necessary level, so the power loss is extremely small and the fuel consumption rate is improved.In addition, the hydraulic pump is stopped when it is not needed, so it can be used later. The effect is great, as there is no possibility that the wheels will be steered due to malfunction.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, with FIG. 1 being a schematic diagram of the overall configuration, and FIG. 2 showing the main components. 4...Natsukuru, 6...Rear wheel, 9...Steering actuator, 15...Steering controller (steering control means), 16...Control valve mechanism, 17...Hydraulic pressure supply mechanism, 18...Hydraulic pressure Controller (steering control means), 41
... Hydraulic pump, 42 ... Motor, 46 ... First
Pressure switch (pressure detection means), 47... second pressure switch (pressure detection means).

Claims (1)

[Scope of utility model registration request] A hydraulic steering actuator that steers and drives rear wheels, a hydraulic pump that supplies hydraulic pressure to the steering actuator, and a motor that drives the hydraulic pump.
an accumulator that is provided between the hydraulic pump and the steering actuator and stores hydraulic pressure supplied from the hydraulic pump to the actuator;
a control valve mechanism provided between the accumulator and the actuator to control hydraulic pressure supplied to the steering actuator; vehicle speed detection means for detecting vehicle speed; steering state detection means for detecting the operation state of the steering wheel; Pressure detection means for detecting the pressure in the accumulator; and a pressure detection means for detecting the pressure in the accumulator; a steering control means for outputting a drive signal to the control valve mechanism to steer the wheels; and a steering control means for outputting a drive signal to the control valve mechanism to steer the wheels; and a hydraulic control means configured to control the drive of the motor to maintain the pressure at the pressure of the vehicle, and to stop the drive of the motor when the vehicle speed exceeds the predetermined value. Rear wheel steering device.