JPH04118378A - Hydraulic feeder for rear-wheel steering system - Google Patents

Abstract

PURPOSE:To avoid any possibility of being incurred into a very dangerous state by constituting a steering shaft so as to be set to a fail-safe mode which restores it to a neutral position, in the case where travel of a spool valve is detected and it has moved abnormally. CONSTITUTION:A rear-wheel steering mechanism 171 is provided with a cylinder chamber 92 installed around a steering shaft 80 supported on a housing 12 shiftably in the axial direction, and a piston 84 partitioning off this cylinder chamber 92 into a first cylinder chamber 94 and a second cylinder chamber 95, and pressure oil for steering rear wheels is fed to either of the first cylinder chamber 94 or second cylinder chamber 95 by means of an axial movement of a spool valve 60 for a spool valve mechanism 148. In this case, there is provided a travel detecting means 69 which detects the extent of axial travel and generates a position signal, whereby the position signal is compared with a reference signal, and when the spool valve shows an abnormal movement, each pressure of both these cylinder chambers 94, 95 is equalized and thereby the steering shaft 80 is reset to the neutral position by a fail-safe mechanism 149.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a hydraulic drive device that supplies hydraulic pressure to a rear wheel steering device for steering rear wheels in a four-wheel steering device to drive the same.

(Prior art) The rear wheel steering device is driven by the pressure oil of the hydraulic drive device.
When steering the rear wheels, the pressure in the cylinder chamber of the rear wheel steering mechanism is controlled by the spool valve mechanism to move the steering shaft in the axial direction to steer the rear wheels.Normally, the steering shaft is moved in the axial direction to steer the rear wheels. The spool valve mechanism for movement is controlled by suction force such as a solenoid or pilot pressure, etc., and in order to move the steered shaft to the target position, a position detection system of the steered shaft provided on the steered shaft is used. The signal from the position sensor is fed back to the control device that controls the solenoids and other devices.

(Problem to be Solved by the Invention) However, in the conventional technology, it has not been confirmed whether the spool valve mechanism is reliably operating in accordance with the operation of the solenoid. Therefore, for example, when the vehicle is running, the spool valve starts to move even though the solenoid is not activated, causing the steering shaft to move and causing a very dangerous situation to be quickly avoided. The problem was that it was not possible.

An object of the present invention is to provide a hydraulic pressure supply device for a rear wheel steering device that can constantly monitor the movement of the spool valve so as not to fall into such a dangerous situation.

(Unprecedented Means for Solving the Problem) In order to solve the above problem, a hydraulic pressure supply device for a rear wheel steering device according to the present invention includes a steering shaft 80 that is movable in the axial direction to steer the rear wheels. , a housing 12 that supports the steered shaft 80 movably in the axial direction, a cylinder chamber 92 provided around the steered shaft 80, and a housing 12 that supports the steered shaft 80 so as to be slidable within the cylinder chamber 92. A rear wheel steering mechanism 171 includes a piston 84 that divides the cylinder chamber 92 into a first cylinder chamber 94 and a second cylinder chamber 95, and a spool valve 60 that supplies pressure oil from a hydraulic source to steer the rear wheels. a spool valve mechanism 148 that supplies either the first cylinder chamber 94 or the second cylinder chamber 95 to move the steered shaft 80 in the axial direction by axial movement of the spool valve 60; a movement amount detection means 69 that detects the amount and generates a position signal, and a control that compares the position signal with a reference signal of the spool valve and generates an abnormal signal when it is determined that the spool valve is moving abnormally. and a fail-safe mechanism 149 for equalizing the pressures in the first cylinder chamber and the second cylinder chamber and returning the steered shaft to the neutral position when receiving an abnormal signal from the control means.

(Function) With the above configuration, the hydraulic pressure supply device for the rear wheel steering device according to the present invention detects the amount of movement of the spool valve and enters a fail-safe mode in which the steering shaft is returned to the neutral position when the spool valve moves abnormally. can do.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

In the accompanying drawing showing the hydraulic drive device 10, a spool 60 and a steering shaft 80 are arranged parallel to each other in the middle part in the height direction of the housing 12, and a pair of mutually parallel solenoids 20 and 30 are arranged above the spool. A solenoid 100 is arranged in a direction perpendicular to the steering shaft 8.
It is placed parallel to 0. The steering shaft 80 is connected to steering rods (not shown) at both ends thereof, and its axial movement steers the rear wheels to the left or right. The solenoids 20, 30 are for controlling the operation of the spool 60, the spool 60 is for controlling the operation of the steered shaft 80, and the solenoid 100 is for so-called fail-safe purposes. These will be explained in detail later.

First, the pressure oil supply device 150 that supplies pressure oil to the hydraulic drive device 10 will be described. This pressure oil supply device includes a pressure oil supply path 152 and a recovery path 154, a pump 156 disposed on the supply path, a check valve 158, and an accumulator 160.
, an oil pressure sensor 162, an unload valve 164 disposed between the supply path and the recovery path, and the like.

A bin rod 23.33 is located in a chamber 21.31 formed above the housing 12 and adjacent to the solenoid 20.30.
is arranged to be movable up and down, and is always kept at a neutral position by springs 22, 32 (32 not shown), but is drawn upward when the solenoid is energized. Bin rod 23.
Chambers 24, 34 (34 is not shown) and 25, 35 are formed on both sides of the upper and lower sides of 33. Passages 41 and 51 branched from the passage 14 formed in the housing 12 and communicating with the supply pipe 152 communicate with the chamber 25.35, respectively, and a fixed throttle 42.52 is formed at the connection between the passage and the chamber. There is. Channels 43, 53, which also branch off from the channel 14, communicate with the chambers 21, 31, respectively. Solenoid 20.
30, chamber 24.34, chamber 25.35, bin rod 23.
33, variable throttle 28, 38, etc., constitute a first or second pilot pressure generating device.

Further, a passage 44.54 branched from the passage 16 formed in the housing 12 and communicating with the recovery pipe 154 is connected to the chamber 27.3.
7 and communicates with the chamber 25.3 through a variable throttle 28.38.
5 can be communicated with.

A chamber 61 formed in the left-right direction in the middle part of the housing 12
Inside, the spool 60 is arranged so as to be movable in the left and right direction. Chambers 72 and 82 on each side of the spool 60
is formed, with which the chamber 25.35 communicates.

The spool 60 has three large diameter sections 63.64 and 65 and is biased inwardly from both sides by springs 73.83. The amount of movement of the spool 60 is measured by a stroke sensor 69 connected thereto. The spool 60 including the large diameter portion 63 and the entrances of the passages 97 and the like constitute a sprue valve.

The passage 14 communicates with an intermediate portion in the longitudinal direction of the chamber 61 at an annular port 66, and the passage 16 communicates with both sides thereof at ports 67 and 68, respectively.

Further below the housing 12, a large hollow portion extending in the left-right direction is formed, and the steering shaft 80 is inserted into this hollow portion. The hollow part has two chambers 91 and 92 having different inner diameters, and the left end part 77 and the middle part 78 of the steering shaft are opposed to these.

A rack portion 87 that meshes with the output shaft 130 of a steering shaft position sensor (not shown) is formed at the right end of the steered shaft 80, and a flange portion 84 with a seal is formed at the intermediate portion 78 to close the intermediate chamber. 92 is divided into two cylinder chambers 94 and 95. Passages 97,98 extending from chamber 61 communicate with chambers 94,95, respectively. A holder 101 is placed in the chamber 92.
is fitted and fixed, and the chamber 6 is inserted into the chamber 102 formed therein.
A passage 103 extending from 6 is in communication.

An inner cylinder 116 is fitted inside the chamber 91 in contact with the holder 101, and a pair of annular portions 122 are provided at the left end 77 of the steering shaft.
．． 123 are formed at a certain distance. A pair of spring retainers 124 and 125 are movably attached to the left end portion 77 between both annular portions, and are biased in directions away from each other by a compression spring 126 interposed between both spring retainers. These annular portions, spring holders, springs, etc. constitute a centering mechanism that maintains the steered shaft at a neutral position. An outer cover 127 of one of the spring holders 124 is screwed onto the left end of the housing 12 . Steering shaft 80, cylinder chamber 94
．． 95, the centering mechanism and the like constitute a rear wheel steering device.

A passage 111 extending from the port 63 communicates with an annular space 112 between both spring holders. In addition, the above chamber 10
2 communicates with a chamber 115 outside the other spring retainer 124 via a passage 114 formed in the center of the steered shaft 80.

A fail-safe control member 135 is disposed in a hollow portion formed at the bottom of the housing 12 and coupled to the output shaft of the solenoid 100. The control member 135 has a generally cylindrical shape and includes three holes 136 extending in the circumferential direction.
．． 137 and 138 are axially spaced apart, so that three seals 139, 140 and 141 remain. Passageways 107.108 extend downwardly from said chambers 94.95 and open into the hollow at ports 141.142, and passageways 106 extend from chamber 102 and open into ports 143. A passage 145 extending from the annular space 112 communicates with the hole 144 at the left end. The control member 135 is moved to the right by the solenoid 100 which is in an energized state when the device is normal, and is moved to the left by the biasing force of the spring 146 when the solenoid is deenergized when an abnormality occurs.

Next, the operation of this embodiment will be explained.

When the solenoid 20.30 is not energized, the bin rod 23.33 is moved downward by the biasing force of the spring 22, etc., and this movement causes the variable throttle 28. 38 are closed. In this state, pressure oil from the supply device 150 is supplied from the supply path 152 into the drive device 10, but does not flow, and the rod bin 23.
The upper and lower chambers 21.25 of the spool 33, the chamber 31.35, and the chambers 72.82 at both ends of the spool 60 are all at the same pressure. Therefore, the spool 60 is in a neutral position where the biasing forces of the pair of springs 73.83 are balanced, and the large diameter portions 63.64 and 65 are opposed to the boats 66.67 and 68, respectively.

Next, when only one solenoid 20 is energized, the rod bin 23 moves upward, the variable throttle 28 opens, and the chamber 25
The high pressure oil inside flows into the chamber 27. Due to this flow, a pressure P1 smaller than the pressure P is generated in the fixed throttle 4L, and a pressure P2 is generated in the variable throttle 28, respectively.

Here, since the chamber 24 does not have a throttle and the high pressure P is directly applied to it, the rod bin 23 is exposed to the pressure P of the fixed throttle 41.
1 and the cross-sectional area 81 of the rod bin 23 (PlxSl)
The sum of the suction force F of the solenoid 20, the high pressure P in the chamber 24, and the cross-sectional area Sl of the rod bin 23! (PxSl) maintains a balanced state.

Here, since the pressure P and the cross-sectional area SL are constants, the pilot pressure P1 is determined by the suction force F of the rod bin 23 generated by the current of the solenoid 20.

The pressure PI of the fixed throttle 42 is applied to the chamber 72, but since the chamber 82 on the opposite side is at a high pressure P, the spool is at a high pressure P.
The pressure difference between and the pilot pressure Pi and the cross-sectional area S of the spool
It moves to the left with a driving force of the product of 2 (P-PL) As a result, the spool valve 148 formed by the large diameter portion 64 and the like and the boat 66 is switched, and the steered shaft 80 can be driven. That is, the large diameter portion 64 of the spool 60 comes off the boat 66 and enters the passage 9.
7, pressure oil is supplied from the passage 14 to the chamber 95 through the passage 98, and the steering shaft 80 is moved to the left.

Even in this state, pressure oil is supplied from the passage 14 to the chamber 102 via the passage 103 and further to the chamber 115 via the passage 114. In this way, a high pressure is supplied to the annular spaces 102, 115 on both sides of the spring holders 124, 125. Since the driving force based on this pressure difference is greater than the biasing force of the spring 126, the spring 116 is compressed and both spring retainers 124.
125 move toward each other, and the annular portion 122.1
Stay away from 23. Therefore, the spring presser does not hinder movement of the steered shaft 80.

On the other hand, when only the other solenoid 30 is energized, the variable throttle 38 opens, the spool 60 moves to the right, pressure oil is supplied to the cylinder chamber 94, and the steered shaft 80
moves to the right. At this time, the spring 126 does not hinder the movement of the steered shaft, as in the case described above.

What has been described above is the first case where the pressure oil drive device is operating normally, and then the case where an abnormality occurs in the pressure oil drive device will be described. The abnormality is a drop in pressure of pressure oil, spool 6
These abnormalities are detected by a sensor (not shown) having the sensor 162, the sensor 69, or the output shaft 130, respectively.

The sensor 69 detects the amount of axial movement of the spool valve 60 and generates a position signal. The control equipment compares this position signal with a reference signal indicating the position where the spool valve should be, and issues an abnormal signal when it is determined that the spool valve has an abnormal weight.

The pressure in the cylinder chambers 94,95 is guided through passages 107, 108 to the hollow portion housing the control section 135 connected to the solenoid 100, and the chambers 102, on both sides of the centering mechanism are introduced through the passages 106. High pressure within 115 is being channeled. In the normal state of the device, the control member 135 of the solenoid 100 is in the advanced position to the right, and the boats 141, 142, and 143 are in the closed portion 139.
140 and 141. Therefore, the pressure oil in the respective passages 106, 107 and 108 are separated from each other, and the steering shaft 80 is moved to the left or right by the pressure applied to the chamber 94 or 95.

However, when an abnormality occurs, the solenoid 100 is demagnetized,
The control member 135 moves to the left by the biasing force of the spring 146,
As a result, the boats 141, 142 and 143 open simultaneously, and the pressure becomes the same momentarily. As a result, the chambers 94 and 95 have the same pressure, so the steered shaft 80 does not move in the axial direction. At the same time, the chambers 102 and 115 and the annular space 112 have the same pressure, and the spring presses 124 and 125
are moved away from each other by the spring 126 and come into contact with the annular portions 122 and 123, thereby centering the steered shaft 80.

(Effects of the Invention) As described above, according to the present invention, since the amount of movement of the spool valve is constantly monitored, abnormal movement of the rear wheel steering mechanism can be quickly detected and the steering shaft can be moved to the neutral position. The system can be set to fail-safe mode, which improves responsiveness and prevents dangerous situations when driving.

[Brief explanation of the drawing]

The accompanying drawing is a front sectional view showing one embodiment of the present invention. Description of symbols of main parts C] 20.30.100: Solenoid 23.33: Rod pin 24.25.34.35: Chamber 28.38: Variable throttle 60 Nisbourg 63.64.65: Large diameter section 69: Stroke sensor 97.98: Passage 80: Steering shaft 94.95 Niji cylinder chamber 122.123: Annular portion 124.125: Spring retainer 126: Spring 135: Control member 162: Hydraulic pressure sensor

Claims (1)

[Claims] 1. A steering shaft that is movable in the axial direction to steer the rear wheels, a housing that supports the steering shaft so as to be movable in the axial direction, and a housing that supports the steering shaft so as to be movable in the axial direction; a rear wheel steering mechanism comprising: a cylinder chamber provided therein; and a piston slidably provided on the steering shaft so as to be slidable within the cylinder chamber and divide the cylinder chamber into a first cylinder chamber and a second cylinder chamber; a spool valve mechanism for supplying pressure oil from a hydraulic source to either the first cylinder chamber or the second cylinder chamber by axially moving a spool valve to move the steered shaft in the axial direction for steering; , a movement amount detection means that detects the amount of axial movement of the spool valve and generates a position signal; and when it is determined that the spool valve is moving abnormally by comparing the position signal and a reference signal of the spool valve. a fail-safe mechanism that equalizes the pressures in the first cylinder chamber and the second cylinder chamber to return the steered shaft to a neutral position when receiving the abnormal signal from the control means; A hydraulic supply device for a rear wheel steering device, comprising: