JPS62110571A - Front and rear wheel steering device - Google Patents

Abstract

PURPOSE:To provide a rear wheel steering characteristic according to the car speed with a simple construction by using the discharge pressure of a pump, which operates synchronously with a rotary shaft to drive the rear wheels, as pilot pressure and thereby controlling the degree of opening of a control valve for steering rear wheels. CONSTITUTION:When operation of a steering wheel 1 switches over a front wheel control valve 2, the pressure oil from a hydraulic pump 5 is sent to one of the pressure chambers in a power cylinder 4, and movement of piston in one direction steers the front wheels 3 through a linkage 7. At the same time, pressure in the power cylinder 4 is transmitted to a rear wheel control valve 14 through divergent passages 15A, 15B, and the pressure oil led to another power cylinder 12 is controlled by this control valve 14, and the rear wheels 10 are steered by the power of this cylinder 12. At this time, the rear wheel control valve 14 uses the discharge pressure of another hydraulic pump 16, which is operated synchronously with rotation of the rear wheels 10, as pilot pressure, and the degree of valve opening is increased/decreased on the basis of this pilot pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in a front and rear wheel steering device in which the front wheels are steered using an IP thread wheel.

(Prior technology) A front and rear wheel steering system is designed to improve vehicle steering stability and responsiveness in high-speed ranges and turning performance in low-speed ranges, and is capable of steering both the front and front wheels. is proposed.

In this case, the rear wheel side steering control further improves the stability of the steering characteristics by variably changing the control flow layer depending on the driving state.

For this reason, for example, what was disclosed in Japanese Patent Application Laid-Open No. 59-186773 is? & The hydraulic pressure supplied to the wheel side control actuator is made to correspond to the front wheel side steering via the controller, and the number of steering operations is controlled according to the driving state at that time.

(Problem to be solved by the invention) In this case, based on the steering signal of the heavy wheels and the output of the vehicle speed sensor, the controller controls the steering characteristics of the rear wheels independently of the front wheels. The optimal rear wheel steering characteristics are obtained according to the driving condition by increasing the amount of steering of the wheels in accordance with the driving conditions. Because it is necessary
The structure was complicated and expensive, and there were problems with reliability.

The present invention aims to solve such problems.

(Means and effects for solving the problem) The present invention provides a front wheel steering actuator that steers the front wheels of a vehicle with the assistance of hydraulic pressure, and a front wheel steering actuator that controls the operating direction and operating force of a steering wheel. In a vehicle equipped with a rear wheel steering actuator that switches and supplies hydraulic pressure from a hydraulic source according to the supplied hydraulic pressure and a rear wheel steering actuator that steers a brake control valve ring for seven wheels according to the supplied hydraulic pressure, the actuator is linked to a rotating shaft that drives the rear wheels. A pump that rotates synchronously with the vehicle speed, a rear wheel control valve whose opening degree increases or decreases in response to the pump discharge pressure that increases depending on the vehicle speed as a pilot pressure, a front wheel steering actuator, and a rear wheel steering actuator. and a passage connected in parallel via a wheel control valve.

Therefore, a portion of the pressure oil supplied to the front wheel steering actuator is supplied to the rear wheel steering actuator via the rear wheel control valve, so that the rear wheels are steered at the same time as the front wheels. When the pump discharge pressure oil increases due to an increase in vehicle speed, the opening degree of the rear wheel control valve increases proportionally. The amount of steering increases, improving driving stability such as high-speed cornering characteristics.

(Example) Embodiments of the present invention will be described below based on the drawings.

In the first embodiment shown in FIG. 1, 1 in the figure is a handle, and 2 is a front wheel control valve that is switched in response to the operation of the handle 1, and the front wheels 3 are steered when the control valve 2 is switched. Power cylinder 4 as a front wheel steering actuator
Meanwhile, the supply of pressure oil from the hydraulic pump 5 is controlled. The control valve 2 is controlled so that hydraulic pressure is generated in a direction corresponding to the operating direction of the handle 1 and in accordance with the operating force. When pressure oil from the hydraulic pump 5 is sent to either one of the left and right pressure chambers 4A, 4B of the power cylinder 4 according to the operating direction and operating force of the handle 1 by this front wheel control valve 2, the other one is a tank. The power cylinder 4 operates in either direction as the hydraulic oil is supplied, and the left and right front wheels 3 are connected to the steering linkage 7 in the same direction as the operating direction of the steering wheel 1. Turn to.

Furthermore, as is well known, the operating force of the handlebar 1 is also transmitted to the front wheels 3 via a steering mechanism consisting of a pinion 8 and a rack 9, and a fail-safe mechanism is adopted that allows the front wheels to be steered even in the event of a failure of the hydraulic system. has been done.

On the other hand, the rear wheel] 0 side also has a steering linkage 11
This makes it possible to steer the steering linkage 11, and a power cylinder 12 is provided as a rear wheel steering actuator to switch the steering linkage 11. In order to maintain the power cylinder 12 in a neutral position, a neutral spring 13, which is similarly loaded with an initial load, is installed in the left and right pressure chambers 12A and 12B.
When the pressures of power cylinder 12B and 12B are almost equal, power cylinder 12
and learn to maintain a stable state of neutrality.

In order to switch and supply pressurized oil to the left and right pressure chambers 12A and 12B of the power cylinder 12 in synchronization with the power cylinder 4 on the front wheel side, the pressure chamber 4A of the power cylinder 4 on the front wheel side is used.
, 4B and the pressure chamber 12A of the power cylinder 12 for the rear wheels,
12B are provided, and a rear wheel control valve 14 is interposed therebetween to control the pressure delivered to the rear wheel side.

This rear wheel control valve 14 operates in accordance with the pressure of the hydraulic pump 16, which is driven by the rotation of the rear wheel 10 (the same as the rotation of the rear wheel 10), to increase or decrease the valve opening. It has become.

The hydraulic pump 16 is gear-driven or belt-driven by a rotary shaft for driving the rear wheels 10, such as a propeller shaft or a drive shaft for the rear wheels, and the pump rotational speed is controlled by VJ control or VJ control depending on the vehicle speed. In other words, as the vehicle speed increases, the pump rotational speed increases, which increases the pump discharge angle and discharge pressure. This pump discharge oil is guided to the lowering control valve 14 through a passage 19, and is also released into the tank 18 through a throttle 17 in the middle, so that the pressure in one passage is proportional to the increase in rotational speed. It has the property of increasing as the temperature increases.

2 and 3 show specific examples of the rear wheel control valve 14, respectively.

A spool 21 is slidably housed in the valve body 20, and the pump discharge pressure is guided as a pilot pressure to a pressure chamber 22 formed at the end of the spool 21 through one passage. The spool 21 is displaced against the spring 23 in response to this pilot pressure, thereby increasing the opening degree of the valve boat 24, 25 that communicates the front wheel side with the rear wheel side.

Therefore, the valve opening degree of the rear wheel control valve 14 increases in proportion to the increase in vehicle speed, increasing the amount of pressure oil guided from the front wheel side to the rear wheel side.

The rear wheel control valve 14 in FIG. 3 has a passage 15A from the rear wheel side.
, drain from the middle of 15f3 through the crest 26,
The pressure on the rear wheel side is controlled to be relatively smaller than the pressure on the front wheel.

This allows the turning angle of the rear wheels to be relatively smaller than that of the front wheels during steering.

The system is constructed as described above, and its operation will be explained next.

When the front wheel control valve 2 is switched to either one by operating the handle 1, one pressure chamber 4A or 4 of the power cylinder 4 is switched.
Pressure oil is fed into B, and the other pressure chamber 4B or 4A is released to the tank side, thereby steering the vehicle in the direction of the front wheels 3 or via the steering linkage 7. At the same time, the pressure of this power cylinder 4 is controlled by parallel branch circuits 15A and 15B.
This is also transmitted to the tkfQ side power cylinder 12 via the rear wheel control valve 14.

In this way, by supplying steering pressure to the power cylinder 12 for the rear wheels, the steering linkage 1
1, the rear wheels 10 are switched in the same direction as the front wheels 3.

In this case, since the rotation of the hydraulic pump 16 is synchronized with the vehicle speed, as the vehicle speed increases, the pump rotation speed also increases, and the pilot pressure acting on the rear wheel control valve 14 increases accordingly, causing the spool 21 to increase. is displaced in accordance with this biro I/pressure, and the valve opening degree increases. Therefore, when the vehicle speed becomes high, the hydraulic oil layer and pressure supplied to the power cylinder 12 as the f4i wheel actuator increase, and the rear wheel steering force increases compared to when the vehicle speed is low.

When driving at high speeds, compared to when driving at low speeds, the lateral acceleration is larger depending on the amount of steering on the front wheels, so if the amount of steering on the rear wheels is correspondingly increased, high speed = 2-knarling characteristics etc. Driving stability is significantly improved.

In this way, when increasing the steering force on the rear wheel side according to the vehicle speed, the hydraulic pump 16? & Since it is mechanically linked to the rotating shaft that drives the wheels 10, there is no need to use a separate vehicle speed detection axle, and there is no need for a controller or pressure control valve to control oil pressure according to vehicle speed. Therefore, the configuration is greatly simplified.

Next, the embodiment shown in FIG. 4 will be explained. In this embodiment, the rear wheel control valve 14 controls the rear wheel control valve 14. This is designed to change the pressure characteristics transmitted to the other side.

For this reason, a direction switching valve 30 is provided which is electromagnetically controlled to switch via the controller 1 to the roller 31 based on the output of the steering sensor 29 that detects the steering direction of the steering wheel 1. The pilot pressure introduced into the left and right pressure chambers 22A and 228 is switched according to the steering (rotation) direction of the handle 1, and the spool 21 is selectively displaced left and right.

As shown in FIG. 5, when the directional control valve 30 is in the E position, the pump discharge pressure is guided to one passage Δ, and the other passage 19B is opened to the tank side, or is controlled by the controller 31. When energized at , it switches to the F position and reverses the pressure relationship. In this case, the spool 21 of the rear wheel control valve 14 is displaced to the left by the directional control valve 30 when high pressure is acting on the passage 15A;
The operating relationship is set in advance so that when high pressure is applied to B, it will be displaced to the right.

Rotate the handle 1, [C passage 15A is high pressure, passage],
When the spool 21 is displaced to the left against the spring 23B when the pressure becomes low, the passage],
5A pressure oil is passed from the boat 24 through the gap A to the spool 21.
via the annular groove 33 formed in the lower a f! T! The other boat 25 communicates with the neutral boat 35 through a check valve 36, and the power cylinder 12
The return oil from the boat 24 flows from the downstream passage 15B to the upstream passage 15B through the annular groove 34 and the neutral boat 35. At this time, a part of the pressure oil from the boat 24 escapes to the neutral boat 35 due to the gap B, and the oil returns to the neutral boat 35. Reduces the pressure transmitted to the wheel side.

The opening relationship between gaps A and B changes reciprocally according to the displacement of the spool 21, so in the low speed range where the displacement of the spool 21 is small, the pressure transmitted to the rear wheel side is low; In the high-speed range where 21 is largely displaced, the gap A opens while the gap B closes, so the transmitted pressure increases.

When the handle 1 is steered in the opposite direction, pressure oil is supplied to the passage 15B, and the passage 15A becomes the low pressure side. At this time, the spool 21 is displaced to the right by the pilot I pressure switched by the directional control valve 30. Pressure oil from the boat 25 flows through the annular groove 3-1 into the downstream passage 15B with a gap, and return oil from the power cylinder 2 flows from the annular groove 33 through the neutral bow 1-35 to the check valve. Passage 1 from 36B
5A, and in this case too, some of the pressure oil flows into gap C.
The pressure is then transferred to the neutral boat 35, and the pressure transmitted to the rear wheels is controlled in the same way as above.

(Effects of the Invention) As described above, according to the present invention, a pump is provided that rotates synchronously in conjunction with the rotating shaft that drives the rear wheels, and the upper k1. Since the opening of the rear wheel control valve is increased/decreased as a result of the pump discharge pressure 3 to the control valve 1, a simple mechanical interlocking configuration eliminates the need for a vehicle speed sensor or controller. This has the effect that the rear wheel side steering characteristic can be provided, the configuration for this purpose is simplified, and the reliability of the operation is also improved.

Brief explanation of pages 1-4 FIG. 1 shows a circuit configuration I'l showing a first embodiment of the present invention.
, No. 2, and No. 3 respectively show rear wheel control valves ((Cross-sectional view showing the space between the bodies). Fig. 4 shows the second embodiment. I&Wakawa control valve (
1 Between bodies 3 Not shown in cross-sectional view (IP) 9] - Handle, 2 - Front wheel control valve, 3... Front wheel, 61... Power cylinder, 4A, 4B - Pressure chamber, 7 ... Suda linkage, 10 ... rear wheel, 1
2... Power cylinder, 12 people, 12B... Pressure chamber, 14... Rear wheel control valve, 15A, 15B... Branch circuit, ]6... Hydraulic pump, ]7... Throttle, 19...
・Aisle, 21...Scale, 22.Assembly room, 23.
・Spring, 2≦)・Steering center→J゛, 30... Directional switching valve, 31... Controller 1-roller.

Patent applicant: Kayabae Gyo Co., Ltd. Figure 1 Figure 2 Figure 3 ni@noguwanrinta゛ Figure 4

Claims (1)

[Claims] a front wheel steering actuator that steers the front wheels of a vehicle with the assistance of hydraulic pressure; a front wheel control valve that selectively supplies hydraulic pressure from a hydraulic source to the front wheel steering actuator according to the operating direction and operating force of a steering wheel; In a vehicle equipped with a rear wheel steering actuator that steers the rear wheels according to supplied hydraulic pressure,
A pump that rotates synchronously in conjunction with the rotating shaft that drives the rear wheels, a control valve for the rear wheels whose opening degree increases or decreases in response to the pilot rod pressure that uses the pump discharge pressure that increases depending on the vehicle speed, and a front wheel rotation control valve. A front and rear wheel steering device comprising: a passage connecting a rudder actuator and a rear wheel steering actuator in parallel via a rear wheel control valve.