JPH0139662Y2 - - Google Patents

Description

[Detailed explanation of the invention] (1) Technical field The present invention is a rear wheel steering system that assists in steering the rear wheels in the same direction as the front wheels, in order to improve running stability during turns, especially when the vehicle is running at high speeds. The present invention relates to a failure detection device for a steering device.

(2) Prior art This type of rear wheel steering device generates hydraulic pressure by squeezing the pressure oil from the oil pump according to the amount of front wheel steering, and uses the hydraulic pressure to operate a hydraulic cylinder to operate the rear wheels in the same manner as the front wheels. Generally, the vehicle is configured to be steered in a direction.

However, if the above hydraulic pressure is not generated due to a malfunction in the rear wheel steering system, rear wheel steering becomes impossible. Since drivers are driving by predicting driving stability, unexpected behavior of the vehicle can be confusing and dangerous.

Therefore, it is preferable to notify the driver of such a failure in the rear wheel steering system in advance, but there has been no failure detection device for this purpose. In addition, if the rear wheel steering hydraulic system including the oil pump is dedicated, the driver cannot intuitively know that the problem has occurred, and it is only when the above-mentioned danger occurs that he or she thinks it is a failure. In this sense, a failure detection device is essential for the rear wheel steering device.

(3) Purpose of the invention From this point of view, the purpose of the invention is to provide a device for detecting the above-mentioned failure.

(4) Structure of the invention The present invention provides a rear wheel steering system of the type described above, which includes a pump drive detection means for detecting when the oil pump is being driven, and a pressure value that the discharge oil pressure of the oil pump should produce while the oil pump is being driven. and a pressure shortage detection means for detecting that the pressure is below the above pressure value, and upon receiving signals from both of these means, an alarm is issued as a malfunction of the rear wheel steering device when the discharge oil pressure is less than the above pressure value even though the oil pump is being driven. The present invention is characterized by being provided with an alarm means.

(5) Embodiments Hereinafter, embodiments of the present invention will be described based on the drawings.

1 to 3 show a rear wheel steering system equipped with the failure detection device of the present invention, and 1 in FIGS.
2 is a left rear wheel of a front-wheel drive vehicle; 2 is a wheel support member that rotatably supports the wheel; 3 is a strut installed between the wheel support member 2 and the vehicle body 4 to extend substantially in the vertical direction of the vehicle body; 5 is a wheel support A transverse link 6 is pivotally inserted between the member 2 and the vehicle body 4 so as to extend substantially in the lateral direction of the vehicle body, and a transverse link 6 is pivotally inserted between the wheel support member 2 and the vehicle body 4 so as to extend generally in the longitudinal direction of the vehicle body. Trailing links are shown respectively.

The transverse link 5 has its outer end attached to the wheel support member 2 so as to be swingable in the vertical direction, and its inner end attached to the third wheel support member 2.
It is attached to the vehicle body 4 via an elastic bush 7 clearly shown in the figure so that it can swing vertically. The elastic bushing 7 is composed of an inner cylinder 7a, an outer cylinder 7b, and an annular rubber body 7c fixed between the inner and outer cylinders, and the outer cylinder 7b is integrally molded on the corresponding end of the transverse link 5. Then, a bolt 9 inserted through a bracket 8 attached to the vehicle body 4 is passed through the inner tube 7a, and this inner tube is positioned in the axial direction by the bracket 8 to attach the inner end of the transverse link 5 to the vehicle body 4.

A hydraulic cylinder 10 is inserted between the front surface of the transverse link 5 and the vehicle body 4 so as to extend in the axial direction of the elastic bushing 7 (in the longitudinal direction of the vehicle body) so as to be able to swing within a substantially horizontal plane. In order to control the expansion and contraction of the hydraulic cylinder 10, an electromagnetic proportional spool valve 11 is provided connected to both cylinder chambers 10a and 10b. It is assumed that the spool 11a is displaced to the right or left in FIG. 1 to supply hydraulic pressure to the chamber 10a or 10b. In order to generate this oil pressure, an oil pump 12 is provided, which sucks oil from an oil tank 13 and supplies it to the valve 11.

In addition, 14 is a steering wheel, and the front wheels are steered by steering operation of the steering wheel, and the vehicle can be steered. The steering direction and steering amount are detected by the steering angle detector 15, which is operated by the solenoid 11b (when steering to the right) or the solenoid 11 depending on the steering direction.
c (during left steering), a current proportional to the amount of steering is supplied through the amplifier 16.

The pump 12 is driven by an on-vehicle engine or an electric motor 17, which is started by an ignition switch (in the case of an on-vehicle engine) or an electric motor switch 18 (in the case of an electric motor). Therefore, the switch 18 continues to drive the pump 12 while it is ON, and in the present invention, the switch 18 is used as the pump 12.
It is used as a pump drive detection means to detect when the pump is being driven. Furthermore, in the present invention, the oil pump 1
A normally closed pressure switch 19 which opens when the discharge oil pressure P ₁ of No. 2 exceeds a set value P _a which is less than the minimum pressure value that should be generated by pump drive is provided as a pressure shortage detection means and also as an alarm means. An alarm device 20 is provided, which are connected in series together with a switch 18, and the series circuit is connected to a battery 21.

The operation of the above embodiment will be explained next. When the engine or electric motor 17 is started by turning on the start switch 18, the oil pump 12 is thereby driven. The oil pump 12 sucks oil from the oil tank 13 and supplies it to the valve 11.
When a is in the neutral position shown in FIG. 1 (when the front wheels are not being steered), all oil flows from the valve 11 to the oil tank 13.
will be returned to. However, due to the flow resistance within the valve 11, a slight discharge oil pressure _P1 is generated on the discharge side of the oil pump 12. This discharge oil pressure P ₁ is
If it is less than the set value P _a , which is set slightly lower than the value that should be generated by driving the oil pump 12, it means that the rear wheel steering hydraulic system is malfunctioning, and at this time the pressure switch 19 changes the discharge hydraulic pressure P ₁ The alarm 20 is activated by the battery 21 when the start switch 18 is closed, and the alarm 20 is activated by the battery 21.
It is possible to notify the driver of a malfunction in the rear wheel steering system. On the other hand, if the discharge oil pressure P ₁ is greater than the set value P _a , then
The rear wheel steering hydraulic system is normal, but at this time the discharge oil pressure
When the pressure switch 19 is opened by _P1 , the alarm 20 is kept inactive, and the driver can confirm that the rear wheel steering hydraulic system is normal by not operating the alarm 20 after the switch 18 is turned on. You can know.

Such a hydraulic rear wheel steering system normally functions as follows. When the vehicle turns to the right by steering the steering wheel 14 to the right, the steering angle detector 15 supplies a current corresponding to the amount of steering to the solenoid 11b via the amplifier 16. At this time, the spool 11a moves to the right in FIG. 1 by an amount corresponding to the steering amount, and the valve 11a moves to the right in FIG.
supplies hydraulic pressure corresponding to the amount of steering to the chamber 10a while draining the chamber 10b. Therefore, the hydraulic cylinder 10
The elastic bushing 7 is deformed in the axial direction by the extension operation, and the transverse link 5 is displaced to the imaginary line position in the direction of the arrow K in FIG. As a result, the rear wheels 1 are also auxiliarily steered in the same direction as the front wheels, as shown by the imaginary lines in FIG. 2, making it possible to ensure the turning stability of the vehicle, especially at high speeds.

Further, while the vehicle is turning to the left by steering the front wheels to the left, the valve 11 causes the hydraulic cylinder 10 to retract by energizing the solenoid 11c in the opposite manner to that described above.
The rear wheels 1 are auxiliarily steered to the left in the same direction as the front wheels, and the turning stability of the vehicle can also be ensured in this case.

Note that when the front wheels are not being steered, the solenoids 11b and 11c of the valve 11 are not energized, and the spool 1
The neutral position of 1a keeps the hydraulic cylinder 10 in an inactive state with both chambers 10a and 10b drained. Thus, the elastic bushing 7 maintains the transverse link 5 in the neutral steer position shown by the solid line in FIG. 1 by elastic return, and does not impede the stability of the vehicle in a straight line.

FIG. 4 shows another example of the device of the present invention. In this example, a normally open turning detection switch 22 is inserted between the pressure switch 19 and the alarm 20, and this switch is activated by the signal from the steering angle detector 15. It shall close when the steering is applied. When this front wheel steering is applied,
As is clear from the explanation of the operation of the above embodiment, the discharge oil pressure _P1 of the oil pump 12 should be a considerably high value that operates the hydraulic cylinder 10, and therefore, in this embodiment, the pressure switch 19 is opened. Set the set pressure P _a to be slightly lower than the above high value.

In this configuration, while the oil pump 12 is being driven with the switch 18 turned on, even though the switch 22 is closed due to front wheel steering, when the pump discharge oil pressure _P1 is below the set pressure P _a , the switch 19 is turned off. The alarm 20 is activated when the alarm 20 does not open.
can be activated to notify the driver of a malfunction in the rear wheel steering hydraulic system. Furthermore, when the rear wheel steering hydraulic system is normal, when the pump discharge oil pressure P ₁ becomes higher than the set pressure P _a and the switch 19 is opened, the alarm 20 is not activated, and the driver can confirm that the rear wheel steering hydraulic system is normal. can be known.

In addition, in the configuration of this example, the opening operation setting pressure P _a of the pressure switch 19 can be increased, and the design of the pressure switch 19 is easy, and malfunctions thereof can be reduced, and failure detection accuracy can be improved. I can do it.

(6) Effects of the invention In this way, the device of the present invention can accurately detect a failure in the rear wheel steering system as described above. It is safe and there is no need to worry about unexpected behavior due to disability.

[Brief explanation of the drawing]

Fig. 1 is a plan view of a left rear wheel suspension for a front-wheel drive vehicle showing a rear wheel steering device equipped with a failure detection device of the present invention; Fig. 2 is an elevational view of the suspension as seen from the rear of the vehicle; FIG. 3 is a sectional view of an elastic bush for attaching the inner end of the transverse link of the same suspension, and FIG. 4 is a circuit diagram showing another example of the present invention. DESCRIPTION OF SYMBOLS 1...Rear wheel, 2...Wheel support member, 3...Strut, 4...Vehicle body, 5...Transverse link, 6...
Trailing link, 7... Elastic bush, 8... Bracket, 9... Bolt, 10... Hydraulic cylinder, 1
1... Electromagnetic proportional spool valve, 12... Oil pump, 13... Oil tank, 14... Steering wheel, 15... Steering angle detector, 16... Amplifier, 17
... Oil pump drive source, 18... Start switch (pump drive detection means), 19... Normally closed pressure switch (insufficient pressure detection means), 20... Alarm (alarm means),
21...Battery, 22...Turn detection switch.

Claims (1)

[Claims for Utility Model Registration] 1. In a rear wheel steering device that uses pressure oil discharged from an oil pump to also steer rear wheels when steering the front wheels, a pump drive detection means for detecting when the oil pump is being driven; , a pressure deficiency detection means for detecting that the discharge oil pressure of the oil pump is less than a pressure value that should occur while the oil pump is being driven; a failure detection device for a rear wheel steering system, comprising an alarm means for warning that the pressure is less than the above pressure value as a failure of the rear wheel steering system. 2. A failure detection device for a rear wheel steering device according to claim 1, wherein the pressure shortage detection means detects when the discharged hydraulic pressure is less than the pressure value during steering.