JPH01162912A - Pressure control valve - Google Patents

Abstract

PURPOSE:To avoid a sudden rise of the output liquid pressure even though a pilot piston is locked by drilling a small hole to the pilot piston to secure communication between a feedback hole and a back chamber and setting a small hole valve to the small hole. CONSTITUTION:The stopper flanges 72 and 82 are attached at one end of two pilot pistons 71 and 81 respectively to control the slide in the depressing direction to a valve spool 20. Then a small hole 82 and a valve groove 84 are formed at the piston 81 (71) and the tip of a plunger 31 (41) has a hemispherical shape so as to close the hole 83. Thus it is possible to avoid the sudden rise of the output liquid pressure for two output circuits 54 and 55 when both pistons 71 and 81 are locked.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to pressure control valves.

(Prior art) As a conventional pressure control valve, for example, Japanese Patent Application Laid-Open No. 57-1828
A conventional pressure control valve, such as the one described in Publication No. 11, is equipped with a pilot piston inside the valve spool that receives feedback hydraulic pressure, and the valve spool is connected to a solenoid or the like. When the output hydraulic pressure increases, the reaction force of the pilot piston that receives the feedback hydraulic pressure acts on the valve spool and pushes the valve spool back, and this reaction force and the valve spool The output hydraulic pressure was controlled to a predetermined pressure by balancing the pressing force against the hydraulic pressure.

(Problem to be Solved by the Invention) However, in such a conventional pressure control valve, there is a possibility that the pilot piston may lock due to contamination of the hydraulic fluid, and in that case, the reaction due to feedback fluid pressure may occur. Since no force is generated, the valve spool will slide significantly due to the pressing force of the pressing means such as a solenoid, causing a sudden pressure rise, and the drive amount of the actuator driven by this output hydraulic pressure will become large. There is a problem in that the pressure control valve is stored away, which is particularly dangerous when such a pressure control valve is used in a vehicle or the like.

(Means for Solving the Problems) An object of the present invention is to provide a pressure control valve in which the output hydraulic pressure does not rise suddenly as described above even when the pilot piston is locked.

To achieve this objective, in the present invention, a back chamber is provided adjacent to the valve body, which is bored in the valve body and connected to the hydraulic pressure supply circuit, the drain circuit, and the output circuit, and which is communicated with the drain circuit at least on one end side. a valve hole, a valve spool slidably provided in the valve hole and capable of selectively connecting an output circuit to a hydraulic pressure supply circuit or a drain circuit to control the hydraulic pressure; a pressing means for pressing in the output circuit pressure increasing direction; a feedback hole bored at the end of the valve spool opposite to the pressing means and into which feedback hydraulic pressure is introduced; A pilot piston is provided, a small hole is formed in the pilot piston and allows communication between the feedback hole and the back chamber; The valve body is formed to be able to be closed and to receive feedback hydraulic pressure, is slidably supported relative to the valve body, and is regulated from a retreating position by a stopper of the valve body, and can slide in the abutment direction. and an energized small hole valve.

(Function) (a) During normal operation, when the valve spool is pressed by the pressing means and slides in the pressure increasing direction, the output hydraulic pressure of the output circuit increases and the feedback hydraulic pressure also increases at the same time.This increased feedback hydraulic pressure Upon receiving the pressure, the pilot piston and small hole valve slide relative to the valve spool and valve body in the pressing direction of the suppressing means, and when this sliding is regulated by the stopper, the pressure received by the pilot piston is reduced. A reaction force acts on the valve spool, and the valve spool is then pushed back by sliding relative to the pilot spool in a direction opposite to the direction in which the pressing means suppresses the valve spool.

The valve spool is arranged at a position where the pressing force of the suppressing means and this reaction force are balanced, and the output hydraulic pressure of the output circuit is controlled to a pressure proportional to the pressing force of the suppressing means.

At this time, the small hole valve receives feedback hydraulic pressure through the small hole and slides due to this received pressure, but since the pilot piston also slides due to the same received pressure, the two remain in contact, The ends of the ostium remain closed.

(b) In the event of an abnormality, if the pilot piston of the feedback hole and the valve spool become clogged with dirt and the pilot spool is locked, the following operation will occur.

First, when the output hydraulic pressure increases and the feedback hydraulic pressure increases due to the sliding of the valve spool, this feedback hydraulic pressure is received by the pilot piston and the small hole valve.

At this time, since the pilot piston is locked, only the small hole valve attempts to slide due to the received pressure, and if this force exceeds the force that urges the pilot piston to come into contact, the small hole valve will move. Separate from the pilot piston. This opens the end of the small hole and brings the feedback hole and the back chamber into communication.

Therefore, the output circuit and the drain circuit are in communication via the feedback hole and the back chamber, and the output hydraulic pressure of the output circuit is not increased.Even if the pilot piston is locked in this way, the output hydraulic pressure remains unchanged. It will not rise rapidly.

(Example) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First, the configuration of the embodiment will be explained.

FIG. 1 is a sectional view showing a pressure control valve according to a first embodiment of the present invention. It consists of a valve bush 60 fitted into the hole 51.

This valve bushing 60 has a valve hole 61 bored in its axis, and this valve hole 61 has a hydraulic pressure introduction hole 62. First drain hole 63. A second drain hole 64° has a first output capotro 5 and a second output capotro 6 formed therein.

The hydraulic pressure introduction hole 62 is connected to the housing 50, communicates with a hydraulic pressure supply circuit 52, and is supplied with hydraulic pressure from the pump P.

Both drain holes 63 and 64 are connected via a communication path 67, and this communication path 67 is also connected to the drain circuit 53 leading to the drain tank T.

The first output port 5 is provided at a position between the first drain hole 63 and the hydraulic pressure introduction hole 62, and is connected to, for example, a rear wheel steering device, etc. via a first output circuit 54 provided in the housing 50. One cylinder chamber S of the actuator (not shown)
connected to l.

The second output port 6 is provided at a position between the second drain 664 and the hydraulic pressure introduction hole 62, and is also connected to a rear wheel steering device, etc. via a second output circuit 55 provided in the housing 50. The other cylinder chamber S of the actuator (not shown)
Connected to 2. That is, taking the actuator of a rear wheel steering device as an example, the operation control is performed such that, for example, the hydraulic pressure of the first output circuit 54 is used to steer the vehicle to the right, and the hydraulic pressure of the second output circuit 55 is used to steer the vehicle to the left. It is something.

In the valve hole 61 is a valve spool 2 whose both ends are pressed by plungers 31 and 41 of the first solenoid 30 and the second solenoid 40, respectively, so that the valve spool 2 is slidable in the left and right directions in the figure.
0 is set.

This valve spool 20 is provided with both ends elastically supported by centering springs 21 and 22, and is provided in an ungrabbed state with the first output captro 5, and has a high-pressure side restrictor a and a drain side restrictor. A first land 20a to be formed, a second land 20b which is provided in an ungrabbed state on the second output port 6 and forms a high pressure side aperture a and a drain side aperture b2, and end lands 20 at both ends.
C, 20d are formed. And each school a
, ,b, ,at,b2 by changing the aperture amount, the first
Both boats 65.6 are adjusted by adjusting the hydraulic pressure introduced into the output capotro 5 and the second output capotro 6 and the hydraulic pressure drained.
6 hydraulic pressure is switched inversely proportionally.

Note that both ends of the valve spool 20 and both solenoids 30
．． 40, a back chamber 56, 56 is provided which communicates with the drain circuit 53 via the communication path 67.

Furthermore, damping orifices 56a and 57a are provided between both back chambers 56, 57 and the communication passage 67.

Spring retainers 23, 24 are provided at the tip ends of the centering springs 21, 22 on the valve spool 20 side, respectively.

The spring retainers 23 and 24 are loosely fitted to both ends of the valve spool 20 and can contact the end lands 20c and 20d to transmit spring force.
．． Flange portions 23a and 24a that can come into contact with 612 are formed.

That is, the spring force of both springs 21.22 is input to the valve spool 20 from the end lands 20c, 20d via both retainers 23.24, and this spring force causes the valve spool 20 to move from the position where it has slid left and right. It is slid toward the neutral position. Further, the movement of both retainers 23, 24 toward the center of the valve spool 20 is restricted by the end surfaces 611, 612 of the valve bushing 60, which serve as stoppers. Therefore, both springs 21 .
The spring force of 22 is no longer input, and sliding due to the spring force is no longer achieved. The position where the valve spool 20 is placed in this state is the neutral position.

The valve spool 20 also has a first feedback hole 70 for guiding the hydraulic pressure of the first output capotro 5 to one end of the valve spool 20, and a first feedback hole 70 for guiding the hydraulic pressure of the second output capotro 6 to the other end. A second feedback hole 80 is drilled to guide the air, and a first pilot piston 71 and a second pilot piston 81 are slidably provided at the tips of both feedback holes 70,80.

A stopper flange 72.82 is provided at one end of both pilot pistons 71.81 to restrict sliding in the recessed direction with respect to the valve spool 20.

As shown in FIG. 2, which is an enlarged view of part A in FIG. ing.

A conical valve groove 84 is formed in the stopper flange 82 which is the tip of the small hole 83 on the back chamber side.
A hemispherical small hole valve portion 31a formed at the tip of the plunger 31 as a small hole valve is arranged in the small hole 84 so as to block communication between the feedback hole 80 and the back chamber 56. He was seated blocking the floor.

Further, as shown in FIG. 1, the plunger 31 is slidably biased toward the valve spool 20 by a solenoid spring 33, and is maintained in the seated state by this biasing force.

Note that the first pilot piston 71 has the same structure as the second pilot piston 81, so a description thereof will be omitted.

The solenoid 30.40 is formed so that the generated attraction force is controlled by the applied control current, and this attraction force causes each plunger 31.41 to slide in the direction of the valve spool 20 and press the valve spool 20. has been done.

In addition, this plunger 3141) has stopper surfaces 32a and 32b formed on the solenoid body 32 (42).
The amount of movement of the plunger 31 (41) is regulated by this. Since the first solenoid 30 and the second solenoid 40 have the same structure, only the internal structure of the first solenoid 30 is shown in FIG.

Next, the operation of the embodiment will be explained.

(a) Normal operation When both solenoids 30 and 40 are driven, the operations are performed symmetrically, so the description will be made regarding when the second solenoid 40 is driven.

When the control current applied to the second solenoid 40 is increased, the plunger 41 pushes the first pilot piston 71 and the valve spool 20 slides to the left in the figure, causing the high pressure side throttle a2 and the drain side throttle bl to At the same time, the drain side throttle b2 and the high pressure side throttle a are narrowed, thereby increasing the hydraulic pressure of the second output capotro 6.

Then, due to the increase in the pressure inside the first feedback hole 80 based on the increase in pressure in the second output port 6, the second pilot piston 81 slides to the left in the figure and presses the plunger 31 of the first solenoid 30. Slide it to the left,
When the slide of the plunger 31 is restricted by the stopper surface 32b, the reaction force of the force pressing the plunger 41 acts on the valve spool 20 in the right direction in the figure, and the valve spool 20 is pushed back. .

Note that when the second pilot piston 81 slides, the small hole valve portion 31a at the tip of the plunger 31
The valve groove 84 is opened by the urging force of the solenoid spring 33.
The small hole 83 is kept seated against the small hole valve part 3.
The closed state is maintained by 1a.

As a result, the valve spool 20 is maintained at a position where the pressing force of the second solenoid 40 and the feedback hydraulic pressure to the valve spool 20 are balanced, and the hydraulic pressure of the second output capotro 6 is maintained at a predetermined hydraulic pressure based on the control current. The actuator and the like connected to the second output circuit 55 are thereby driven.

Note that when the first solenoid 30 is driven, the valve spool 20 slides to the right in the figure, and the hydraulic pressure of the first output capotro 5 is controlled to a predetermined hydraulic pressure based on the control current. .

(b) In the event of an abnormality The operation in the event of an abnormality in which the second pilot piston 81 is locked due to dirt or the like being clogged between the second pilot piston 81 and the valve spool 20 will be explained.

When the second solenoid 40 is driven, the valve spool 20 slides to the left in the figure in the same way as described above, the output hydraulic pressure of the second output circuit 55 increases, and at the same time the second feedback hole 80 Feedback hydraulic pressure also increases.

This feedback hydraulic pressure is received by the second pilot piston 81 and the small hole valve portion 31a of the plunger 31.

However, since the second pilot piston 81 is in a locked state and does not slide, when the pressure received by the small hole valve portion 31a of the plunger 31 exceeds the biasing force of the solenoid spring 33, only the plunger 31 slides and the small hole valve portion 31a of the plunger 31 slides. The hole valve portion 31a is opened, and the feedback hole 80 and the back chamber 56 are brought into communication via the small hole 83. That is, the second
The output circuit 55 and the drain circuit 53 are connected to the second feedback hole 80 . The back chamber 56 and the communication passage 67 are in communication with each other, and the fluid pressure in the second output circuit 55 is prevented from increasing rapidly.

Incidentally, even when the first pilot piston 71 is locked, the hydraulic pressure in the first output circuit 54 is similarly prevented from increasing rapidly.

In this way, in the first embodiment, the pilot piston 8i7
1) with a small hole 83 and a valve groove 84, and the tip of the plunger 31 (41) is formed into a hemispherical shape so that the small hole 83 can be closed. When locked, both output circuits 5
4.55 is prevented from rapidly increasing the output hydraulic pressure.

Next, a second embodiment of the present invention will be described.

FIG. 3 is an enlarged sectional view showing a main part of the second embodiment, and shows a portion corresponding to section A in FIG. 1.

Reference numeral 200 designates a pilot piston, which is formed into a cylindrical shape and has a small hole 201 bored in its axis.

A valve retainer 203 as a small-hole valve is fitted to the tip of the plunger 41, and a valve groove 204 is formed in the valve retainer 203 to abut the pilot piston 200 and close the small hole 201.

Note that the other configurations are the same as those in the first embodiment, so explanations will be omitted.

Therefore, in this second embodiment, the second (first)
When the feedback hydraulic pressure in the feedback hole 80 (70) increases, the valve retainer 203 moves into the valve groove 20.
4, the small hole 201 is kept closed, and the pilot piston 20
In the event of an abnormality in which 0 is locked, this valve retainer 203
moves away from the valve groove 204 and opens the small hole 201, preventing a sudden increase in output hydraulic pressure.

Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment. For example, in the embodiment, an example in which two output circuits are provided is shown, The present invention may also be applied to a device with one output circuit.

Further, in the embodiment, a solenoid is shown as the suppressing means, but hydraulic pressure such as oil pressure of a hydraulic circuit, or other means such as a piston or a motor may be used. For example, when the pressure control valve of the present invention is connected to a rear wheel steering device and the rear wheel steering device is operated in accordance with the amount of steering of the front wheels, the pressure control valve of the present invention is transmitted from the power steering device in accordance with the amount of steering of the front wheels. The valve spool may be pressed by hydraulic pressure.

(Effects of the Invention) As explained above, in the pressure control valve of the present invention, the pilot piston is provided with a small hole that communicates the feedback hole with the back chamber, and a small hole valve is provided in this small hole. Even if the pilot piston is locked, a sudden increase in the output hydraulic pressure can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a pressure control valve according to a first embodiment of the present invention;
FIG. 2 is an enlarged sectional view showing part A in FIG. 1, and FIG. 3 is an enlarged sectional view showing main parts of a pressure control valve according to a second embodiment of the present invention. 10... Valve body 20... Valve spool 30... First solenoid (pressing means) 31 a---
Small hole valve part (small hole valve) 32 a-=stopper surface (
Stopper) 32 b--Stopper surface (stopper) 40--Second
Solenoid (pressing means) 52--Liquid pressure supply circuit 53--Drain circuit 54--First output circuit 55--Second output circuit 56--Back chamber 57--Back chamber 61--Valve Hole 70...First feedback hole 71...First pilot piston 80-...Second feedback hole 81...Second pilot piston 83...Small hole 200-...Pilot piston 201...Small Hole 203... Valve retainer patent application Hitotatsugi Auto Parts Co., Ltd.

Claims (1)

[Claims] 1) A valve that is bored in the valve body and connected to a hydraulic pressure supply circuit, a drain circuit, and an output circuit, and has a back chamber adjacent to it that communicates with the drain circuit on at least one end side. a valve spool which is slidably provided in the valve hole and whose output circuit is selectively connected to a hydraulic pressure supply circuit or a drain circuit and whose hydraulic pressure can be controlled; a pressing means for pressing in the pressure direction; a feedback hole bored at the end of the valve spool opposite to the pressing means and into which feedback hydraulic pressure is introduced; and a feedback hole provided slidably within the feedback hole. a pilot piston; a small hole drilled in the pilot piston that allows communication between the feedback hole and the back chamber; and a small hole that can abut an end of the small hole on the back chamber side and close the end of the small hole. The valve body is formed so as to be able to receive feedback hydraulic pressure, and its retreat position is regulated by a stopper of the valve body, and is slidably supported relative to the valve body and is biased to slide in the abutment direction. A pressure control valve comprising: a small hole valve; and a pressure control valve.