JPH0821550A - Flow control valve - Google Patents

Abstract

(57) [Summary] [Purpose] Prevents surge pressure from being applied to the pump. [Structure] A discharge port 10 for supplying hydraulic fluid to an actuator is provided, a spool accommodating hole 2 having a drain port 7 opened is formed on a wall surface, and a spool valve 3 is slidably accommodated in the spool accommodating hole 2. To form a high pressure chamber 4 and a back pressure chamber 5 so that the discharge side of the pump 8 communicates with the high pressure chamber 4.
In the flow control valve in which the high pressure chamber 4 is communicated with the discharge port 10 via the orifice 11 and the discharge port 10 is communicated with the back pressure chamber 5, a communication passage 22 for communicating the back pressure chamber 5 with the drain port 7 is provided. And a surge valve 23 that is opened only when the pump 8 is started at a low temperature is provided in the communication passage 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow rate control valve for properly controlling the flow rate of hydraulic fluid supplied to an actuator such as a power steering device by a pump driven by an engine or the like in a vehicle.

[0002]

2. Description of the Related Art Conventionally, as a flow rate control valve of this type, there is one described in Japanese Patent Laid-Open No. 58-185367.

This flow control valve is provided with a control valve port (discharge port) for supplying pressure oil (working fluid) to a power cylinder or the like (actuator), and a suction chamber (drain port) is opened on the wall surface of the valve chamber. A (spool accommodating hole) is formed, and a cylindrical oil return control spool (spool valve) whose both ends are closed is slidably accommodated in the valve chamber to partition the high pressure chamber and the back pressure chamber. The discharge side of the pump is communicated with the high pressure chamber, the high pressure chamber is communicated with the control valve port through an orifice (orifice), and the control valve port is communicated with the back pressure chamber.

Then, the oil return control spool is made to respond to the differential pressure generated before and after the throttle, and the opening area of the suction port is adjusted by the oil return control spool to control the supply flow rate of the pressure oil to the power cylinder and the like. I have to.

Further, in the oil return control spool, there is provided a relief valve for connecting the back pressure chamber and the suction port when the pressure on the downstream side of the orifice becomes high.

[0006]

However, in the above conventional flow rate control valve, when the pump is started at a low temperature, the hydraulic oil is in a low temperature state and its viscosity is high, so that the hydraulic oil does not easily pass through the throttle. Therefore, it is difficult for the hydraulic oil to flow from the high pressure chamber to the control valve port. Therefore, when the hydraulic oil is supplied to the high pressure chamber by the pump, the pressure in the high pressure chamber rises.
At this time, since the hydraulic oil in the back pressure chamber also has a high viscosity, the hydraulic oil flows to the control valve port side due to the flow passage resistance such as the communication passage connecting the back pressure chamber and the control valve port and the throttle of the rotary valve of the power steering. hard.
Therefore, even if the pressure in the high pressure chamber rises, the oil return control spool cannot be easily moved, and the suction port is not easily opened. Thus, the pressure in the high pressure chamber further rises, and an excessive pressure (surge pressure) exceeding the discharge load of the pump acts on the pump.

The present invention has been made to solve the above problems, and an object thereof is to prevent a surge pressure from being applied to a pump.

[0008]

To achieve the above object, according to the present invention, as described in claim 1, a discharge port for supplying a working fluid to an actuator is provided, and a drain port is opened on a wall surface. A spool accommodating hole is formed, a spool valve is slidably accommodated in the spool accommodating hole to define a high pressure chamber and a back pressure chamber, and the discharge side of the pump is communicated with the high pressure chamber, and the high pressure chamber is In the flow control valve, which communicates with the discharge port through an orifice and communicates the discharge port with the back pressure chamber, a communication passage is formed for communicating the back pressure chamber and the drain port. Is provided with a surge valve that opens only when the pump is cold started. More specifically, as described in claim 2, the back pressure chamber is partitioned to form a valve accommodating chamber, Between the accommodation chamber and the back pressure chamber A hole is provided, a valve element is arranged in the valve accommodating chamber so that the through hole can be opened and closed, and the valve accommodating chamber is divided into a communication chamber on the side of the through hole and a sub back pressure chamber, and the communication chamber has the above-mentioned structure. The surge valve is configured such that the communication passage is opened and an elastic member that elastically biases the valve body in a direction of opening the through hole is interposed.

[0009]

According to the above structure, when the pump is started at a low temperature, the working fluid is in a low temperature state and has a high viscosity, which makes it difficult for the working fluid to pass through the orifice. Rises. At this time, the surge valve opens and the back pressure chamber communicates with the drain port, that is,
The back pressure chamber is at about atmospheric pressure. Therefore, the spool valve instantaneously retracts to the position where the drain port is opened by the pressure of the high pressure chamber, and as a result, the spool valve escapes to the drain port before the pressure of the high pressure chamber rises. Then, after the pump is started, the surge valve is closed and the pressure of the discharge port acts on the back pressure chamber, so that the spool valve moves according to the differential pressure generated before and after the orifice.

Further, according to the configuration of claim 2,
When the pump starts cold, the pressure in the high pressure chamber rises, but at this time, the valve element moves in the direction to open the through hole by the force of the elastic member, and the surge valve is opened, that is, the back pressure chamber is opened. The back pressure chamber is at approximately atmospheric pressure in a state of being communicated with the drain port via the communication passage. Therefore, the spool valve instantaneously retracts to the position where the drain port is opened by the pressure in the high pressure chamber, and as a result, the spool valve is released to the drain port before the pressure in the high pressure chamber rises. When the viscosity of the hydraulic fluid becomes low after the pump is started, the pressure at the discharge port rises, and this pressure is supplied to the sub back pressure chamber and acts on one side of the valve body. On the other side, only the pressure of the back pressure chamber, which is in low pressure and is in communication with the drain port, acts. At this time, since the valve element is moved in the direction of opening the through hole by the force of the elastic member, the pressure receiving areas on both sides of the valve element are equal. Therefore, a force for urging the valve body toward the back pressure chamber is generated in the valve body, and the valve body overcomes the force of the elastic member and is instantly moved in the direction of closing the through hole to close the through hole. As a result, the surge valve closes, which cuts off the communication passage and prevents the back pressure chamber from communicating with the drain port, so the pressure in the discharge port also acts on the back pressure chamber and acts on both sides of the valve element. The pressure is the same. However, after closing the surge valve, the pressure receiving area on the back pressure chamber side of the valve body is reduced to the opening area of the through hole, and there is a difference between the pressure receiving areas on both sides. The urging force is maintained, and as a result, the state in which the communication passage is blocked by the valve body is maintained. Therefore, the spool valve moves according to the differential pressure generated before and after the orifice.

[0011]

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

FIG. 1 is a vertical sectional view showing a flow control valve according to an embodiment of the present invention.

A spool accommodating hole 2 is formed in the casing 1, and a spool valve 3 is slidably accommodated in the spool accommodating hole 2 to define a high pressure chamber 4 and a back pressure chamber 5. Reference numeral 6 is a return spring arranged in the back pressure chamber 5.

On the wall surface of the spool accommodating hole 2, the discharge side of the drain port 7 and the pump 8 (only the pump high pressure chamber is shown) whose effective flow passage cross-sectional area is controlled by the spool valve 3 is connected to the high pressure chamber 4. The inflow port 9 for communication is open.

A cylindrical connector is screwed into one end of the spool accommodating hole 2 which faces the high pressure chamber 4, and a discharge port 10 and an orifice 11 are provided in the connector. The discharge port 10 communicates with the high pressure chamber 4 via an orifice 11 to supply hydraulic fluid to the power steering device (actuator) side outside the system, and communicates with the back pressure chamber 5 via a communication passage 12. are doing. Reference numeral 13 is an orifice provided in the communication passage 12 in order to prevent the pulsation of the pressure of the discharge port 10 from being transmitted to the back pressure chamber 5.

Further, when a load is applied to the spool valve 3 from the power steering device (actuator) side and the pressure of the back pressure chamber 5 becomes high, the back pressure chamber 5 and the drain port 7 are communicated with each other. A relief valve 25 is provided.

Further, the back pressure chamber 5 and the drain port 7
A communication passage 22 is formed to communicate with, and a surge valve 23 is provided in the communication passage 22.

That is, the back pressure chamber 5 is partitioned by the partition wall 1a to form the valve accommodating chamber 14, and the valve accommodating chamber 14 is formed.
A through hole 15 is provided between the back pressure chamber 5 and the back pressure chamber 5 (partition wall 1a).

A valve body 17 is arranged in the valve accommodating chamber 14 so as to open and close the through hole 15, and the valve accommodating chamber 14 is separated into a communication chamber 18 and a sub back pressure chamber 19 on the side of the through hole 15. Is made.

Further, in the communication chamber 18, the through hole 15
A spring 20 (elastic member) that elastically biases the valve element 17 in the direction of opening the valve is interposed. 16 is the valve body 1
7 is a valve seat formed at the opening edge of the through hole 15 so that the seat 7 can be seated.

Further, the casing 1 has a communication passage 21 for communicating the communication chamber 18 with the drain port 7.
And a communication passage 24 that communicates the sub back pressure chamber 19 and the discharge port 10 with each other. Reference numeral 26 is an orifice provided in the communication passage 24 in order to prevent the pulsation of the pressure of the discharge port 10 from being transmitted to the sub back pressure chamber 19.

Thus, the through hole 15 and the communication chamber 1
8 and the communication passage 21 constitute the communication passage 22, and in the communication passage 22, a surge valve 23 that opens only when the pump 8 is started at a low temperature is formed in the communication passage 22, as described later.

In the above structure, when the pump 8 is started at a low temperature, the working fluid is also in a low temperature state and has a high viscosity. Therefore, it is difficult for the working fluid to pass through the orifice 11, so that the pressure in the high pressure chamber 4 rises. At this time, the surge valve 23
The valve body 17 is separated from the valve seat 16 by the force of the spring 20 and is pressed against the other end of the valve accommodating chamber 14,
Is opened, and the valve is opened.
The state in which the back pressure chamber 5 is communicated with the drain port 7 via, that is, the back pressure chamber 5 is substantially at atmospheric pressure. Therefore, the spool valve 3
Is instantaneously retracted to the position where the drain port 7 is opened by the pressure of the high pressure chamber 4, and as a result, the pressure in the high pressure chamber 4 is released to the drain port 7 before it rises.

After the pump 8 is started, that is, when the pressure of the high pressure chamber 4 is released after the pump 8 is started at a low temperature, the pressure of the discharge port 10 rises when the viscosity of the working fluid becomes low, and this pressure becomes The back pressure chamber 5 is supplied to the sub back pressure chamber 19 through the communication passage 24 and acts on one side of the valve body 17, while the other side of the valve body 17 communicates with the drain port 7 and has a low pressure. Only the pressure of is acting. At this time, since the valve body 17 is moved by the force of the spring 20 in the direction of opening the through hole 15 and is separated from the valve seat 16, the pressure receiving areas on both sides of the valve body 17 are equal. Therefore, the valve body 1
A force for urging this toward the back pressure chamber 5 side is generated in the valve 7, and the valve element 17 overcomes the force of the spring 20 and the through hole 1
5 is instantly moved in the closing direction to sit on the valve seat 16 and close the through hole 15. As a result, the surge valve 23 is closed, and thereby the communication passage 22 is blocked and the back pressure chamber 5 is no longer communicated with the drain port 7. Therefore, the back pressure chamber 5 is also communicated with the discharge port 10 via the communication passage 12. Pressure acts on both sides of the valve body 17, and the pressures acting on both sides of the valve body 17 are the same. However, after the surge valve 23 is closed, the pressure receiving area of the valve body 17 on the back pressure chamber 5 side is narrowed to the opening area of the through hole 15 and a difference occurs between the pressure receiving areas on both sides. The force for urging the pressure chamber 5 side is maintained, and as a result, the valve body 17 moves toward the valve seat 1
6 is held, and the state in which the communication passage 22 is blocked is maintained.

As described above, the surge valve 23 is opened only when the pump 8 is started at a low temperature, and is closed otherwise. After the surge valve 23 is closed, the back pressure chamber 5 is provided with the discharge port 1.
A pressure of 0 acts. As a result, a differential pressure generated before and after the orifice 11 acts on the front and rear of the spool valve 3, and the spool valve 3 moves in accordance with this differential pressure, so that the supply flow rate of the hydraulic fluid to the power steering device will be described later. Will be properly controlled.

That is, when the pump 8 is rotating at a low speed, the discharge flow rate of the hydraulic fluid is small, and therefore the differential pressure across the orifice 11 is small.
Does not move enough to open. Therefore, the entire amount of the hydraulic fluid flowing into the high pressure chamber 4 is supplied to the power steering device. As a result, the assist force of the power steering device is increased and the steering force is reduced. Further, when the pump 8 is rotating at a medium speed or a high speed, the discharge flow rate of the hydraulic fluid is large, and therefore the differential pressure before and after the orifice 11 is large, so that the spool valve 3 overcomes the force of the return spring 6 and moves to the drain. A gap (not shown) is generated between the port 7 and the end surface of the spool valve 3 on the drain port 7 side. Therefore, a part of the hydraulic fluid is discharged to the drain port 7 through the gap, so that the flow rate supplied to the power steering device becomes constant. As a result, the assist force of the power steering device becomes constant, and a constant steering force can be obtained.

In the above embodiment, the surge valve 23 is hydraulically operated. However, if the surge valve 23 is opened in the communication passage 22 only when the pump 8 is started at a low temperature, and closed otherwise, the surge valve 23 is used. May be constituted by a solenoid valve or the like.

[0028]

As described above, according to the present invention, as described in claim 1, the actuator is provided with the discharge port for supplying the working fluid, and the wall is formed with the spool accommodating hole having the drain port opened. A spool valve is slidably accommodated in the spool accommodating hole to partition and form a high pressure chamber and a back pressure chamber, the discharge side of the pump is communicated with the high pressure chamber, and the high pressure chamber is connected to the discharge port through an orifice. In the flow rate control valve, which is in communication with the discharge port in communication with the back pressure chamber, a communication passage is formed for communicating the back pressure chamber with the drain port, and the communication passage is provided at the time of low temperature start of the pump. Since a surge valve that opens only is provided, the hydraulic fluid is in a low temperature state and has a high viscosity immediately after the pump is started.This makes it difficult for the hydraulic fluid to pass through the orifice, so the pressure in the high pressure chamber rises. At low temperature startup, the surge valve opens and the back pressure chamber is in communication with the drain port through the communication passage, and the back pressure chamber is at approximately atmospheric pressure. It is possible to instantly retreat the drain port to a position where the drain port is opened by the pressure of 1 to release the pressure of the high pressure chamber to the drain port. As a result, it is possible to surely prevent the surge pressure from being applied to the pump. Then, after the low temperature start of the pump, the surge valve is closed, the pressure of the discharge port is applied to the back pressure chamber, and the spool valve can be moved according to the differential pressure generated before and after the orifice.

As described in claim 2, the back pressure chamber is partitioned to form a valve accommodating chamber, and a through hole is provided between the valve accommodating chamber and the back pressure chamber, and the through hole is formed. A valve element is arranged in the valve accommodating chamber so as to be openable and closable, and the valve accommodating chamber is divided into a communication chamber on the side of the through hole and a sub back pressure chamber, and the communication passage is opened in the communication chamber. When the surge valve is configured by interposing an elastic member that elastically biases the valve body in the direction of opening the through hole, the pressure in the high pressure chamber rises when the pump is started at a low temperature. , The valve body moves in the direction to open the through hole by the force of the elastic member, and the surge valve is opened, that is, the back pressure chamber is in communication with the drain port through the communication passage. The chamber is at about atmospheric pressure. Therefore, the spool valve can be instantaneously retracted by the pressure of the high pressure chamber to a position where the drain port is opened, and the pressure of the high pressure chamber can be released to the drain port. As a result, it is possible to surely prevent the surge pressure from being applied to the pump. And, after the pump is started, the viscosity of the hydraulic fluid becomes low,
The pressure of the discharge port rises, and this pressure is supplied to the sub back pressure chamber and acts on one side of the valve body, but on the other side of the valve body,
Only the pressure of the low-pressure back pressure chamber that is in communication with the drain port is applied, so the valve body is moved in the direction to open the through hole by the force of the elastic member, and the pressure receiving areas on both sides of the valve body are Since they are equal to each other, a force that urges the valve element toward the back pressure chamber side is generated, and the valve element overcomes the force of the elastic member to instantly move in the direction of closing the through hole to close the through hole. , The surge valve can be closed. As a result, the back pressure chamber is no longer in communication with the drain port, so the pressure in the discharge port also acts on the back pressure chamber, and the pressure acting on both sides of the valve body is the same, but after closing the surge valve, Since the pressure receiving area on the back pressure chamber side of the body is narrowed to the opening area of the through hole, there is a difference between the pressure receiving areas on both sides, and the force that biases the valve body toward the back pressure chamber side is maintained. The state in which the communication passage is blocked can be maintained by applying the pressure of the discharge port to the back pressure chamber. Therefore, after the pump is started, the pressure of the discharge port is applied to the back pressure chamber, and the spool valve can be moved according to the differential pressure generated before and after the orifice.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a flow control valve according to an embodiment of the present invention.

[Explanation of symbols]

 2 Spool accommodation hole 3 Spool valve 4 High pressure chamber 5 Back pressure chamber 7 Drain port 8 Pump 10 Discharge port 11 Orifice 14 Valve accommodation chamber 15 Through hole 17 Valve body 18 Communication chamber 19 Sub back pressure chamber 20 Spring (elastic member) 22 stations Passage 23 Surge valve

Claims (2)

[Claims] 1. A high pressure chamber having a discharge port for supplying hydraulic fluid to an actuator, a spool accommodating hole having a drain port opened in a wall surface, and a spool valve slidably accommodated in the spool accommodating hole. And the back pressure chamber are partitioned and formed,
The discharge side of the pump communicates with the high pressure chamber, the high pressure chamber communicates with the discharge port through an orifice, and the discharge port communicates with the back pressure chamber. A flow control valve, characterized in that a communication passage communicating with the drain port is formed, and a surge valve that is opened only when the pump is started at a low temperature is provided in the communication passage. 2. A valve accommodating chamber is formed by dividing the back pressure chamber, a through hole is provided between the valve accommodating chamber and the back pressure chamber, and the through hole can be opened and closed in the valve accommodating chamber. A valve body is arranged to divide the valve accommodating chamber into a communication chamber on the side of the through hole and a sub back pressure chamber, the communication passage is opened in the communication chamber, and the communication hole is opened in the direction described above. The flow control valve according to claim 1, wherein the surge valve is configured by interposing an elastic member that elastically biases the valve body.