JPH076572U - Flow control valve - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a flow control valve capable of reducing the pressure difference generated before and after a gap through which excess hydraulic fluid passes in front of a drain passage to reduce the influence on the wall surface of the drain passage. [Structure] Spool housing hole 2 communicating with the discharge side of the pump
And a spool valve 3 housed in the spool housing hole 2,
A drain passage 10 that is opened in the spool accommodating hole 2 and is controlled to be opened and closed by the spool valve 3 is provided. In the flow control valve that controls the flow rate to the actuator by discharging the portion, the variable throttle 12 is provided in the drain passage 10 downstream from the opening opened and closed by the spool valve 3.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a flow rate control valve that appropriately controls the flow rate of hydraulic fluid supplied from an engine-driven pump to an actuator such as a power steering device in a vehicle.

[0002]

[Prior art]

 Conventionally, as a flow control valve of this type, there is one described in Japanese Patent Laid-Open No. 62-283267. This flow control valve guides the discharge hydraulic fluid of the pump to the spool accommodating hole, and the spool valve that slides back and forth in the spool accommodating hole opens and closes the drain passage that opens in the spool accommodating hole and discharges the pump from the drain passage. A part of the hydraulic fluid is discharged to supply the required amount of hydraulic fluid to the actuator.

[0003]

[Problems to be solved by the device]

 By the way, when the flow rate of the pump discharge hydraulic fluid flowing into the spool accommodating hole increases, a gap is created between the drain passage and the end surface of the spool valve on the drain passage side. Part of this, that is, the excess hydraulic fluid is discharged from the spool accommodating hole to the opening of the drain passage while being squeezed in the gap. The discharge flow rate increases as the flow rate of the pump discharge hydraulic fluid increases. In particular, when the vehicle is traveling at high speed, that is, when the pump is rotating at high speed, the discharge flow rate of the excess hydraulic fluid increases, and when the excess hydraulic fluid passes through the gap, the pressure difference generated before and after the gap is large. Become. In this case, the excess hydraulic fluid discharged into the drain passage will have a large kinetic energy. As a result, the excess hydraulic fluid may violently collide with the wall surface of the drain passage and affect it.

The present invention has been made to solve the above problems, and its purpose is to reduce the pressure difference generated before and after a gap through which excess hydraulic fluid passes before the drain passage to reduce the drain passage. It is to provide a flow control valve that can reduce the influence on the wall surface.

[0005]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the present invention has a spool housing hole communicating with the discharge side of a pump, a spool valve housed in the spool housing hole, and an opening in the spool housing hole, and opening / closing control by the spool valve. And a drain passage for controlling the flow rate of the actuator by opening the drain passage by sliding the spool valve and discharging a part of the pump discharge hydraulic fluid. A variable throttle is provided in the drain passage downstream of the opening that is opened and closed.

[0006]

[Action]

 According to the above configuration, when a part of the pump discharge hydraulic fluid discharged to the drain passage, that is, the flow rate of the excess hydraulic fluid increases as the flow rate of the pump discharge hydraulic fluid increases, the drain passage and the drain passage side spool A gap is created between the valve end surface and the drain passage, and a throttle portion is also created in the drain passage by the variable throttle. Therefore, the surplus hydraulic fluid flows in multiple stages before the opening of the drain passage and at the variable throttle portion. Thus, the pressure difference between the front and rear of each of the multistage throttles is a gradual decrease of the pressure difference before and after the conventional gap, so the flow velocity from the spool accommodating hole to the drain passage is reduced. The kinetic energy of is reduced, and the erosion effect exerted on the wall surface of the drain passage when the excess hydraulic fluid flows through the drain passage is reduced.

[0007]

【Example】

 An embodiment 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.

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 separate a high pressure chamber 4 and a back pressure chamber 5. 6 is a return spring.

A discharge passage 7 connected to an actuator (not shown) is provided at one end of the spool housing hole 2 on the high pressure chamber 4 side, and an orifice 8 is provided between the discharge passage 7 and the high pressure chamber 4. Is provided.

The discharge passage 7 communicates with the back pressure chamber 5 through a communication passage 9 and an orifice (not shown). A discharge side of a pump (not shown) communicates with the high-pressure chamber 4 via an inflow passage 21.

A drain passage 10 that is opened in the spool housing hole 2 and is controlled to be opened and closed by the spool valve 3 is connected to the spool housing hole 2. Then, the drain valve 10 is opened by sliding the spool valve 3 to discharge a part of the pump discharge working fluid (hereinafter, simply referred to as excess working fluid) to control the flow rate to the actuator.

Further, in the drain passage 10 downstream of the opening opened and closed by the spool valve 3, there is provided a variable throttle 12 which operates with an increase in the pressure of the pump discharge working fluid.

That is, the casing 1 is formed with a sub-spool accommodation hole 13, and a sub-spool valve 14 for restricting the drain passage 10 is slidably accommodated in the sub-spool accommodation hole 13 to form a high pressure chamber. 15 and the back pressure chamber 16 are separated from each other.

The high-pressure chamber 15 communicates with the high-pressure chamber 4 via a communication hole 17, and the back-pressure chamber 16 is located in the drain passage 10 downstream of the sub-spool valve 14 and has a communication hole 18 and an orifice 19. Through the. 20 is a return spring.

An annular groove 14a is formed on the outer peripheral portion of the sub spool valve 14 so that the upstream side and the downstream side of the sub spool valve 14 in the drain passage 10 communicate with each other, and the high pressure chamber of the annular groove 14a is formed. A land portion 14b for narrowing the drain passage 10 is formed on the 15 side.

According to the above configuration, the pump discharge working liquid that has flowed into the spool housing hole 2 flows to the actuator via the orifice 8 and the discharge passage 7. The pressure difference generated before and after the hydraulic fluid passes through the orifice 8 acts before and after the spool valve 3. When the pump is running at a low speed, the pressure difference before and after the spool valve 3 is small, so the spool valve 3 does not move so much as to open the drain passage 10. Therefore, the entire amount of the hydraulic fluid that has flowed into the spool housing hole 2 is supplied to the actuator. Further, when the pump rotates at medium speed and high speed, the pressure difference between the front and rear of the spool valve 3 is large, so that the spool valve 3 overcomes the spring force of the return spring 6 and slides. As a result, a gap (not shown) is generated between the drain passage 10 and the end surface of the spool valve 3 on the drain passage 10 side, and the excess hydraulic fluid is discharged to the drain passage 10 through the gap. Therefore, the supply flow rate to the actuator becomes almost constant.

When the pressure in the high pressure chamber 4 is low, the pressure in the high pressure chamber 15 communicating with the high pressure chamber 4 is also low, so that the sub spool valve 14 does not move due to the spring force of the return spring 20. At this time, as shown in FIG. 1, the annular groove 14a of the sub spool valve 14 is in complete communication with the downstream side of the drain passage 10 from the sub spool valve 14. However, when the pressure in the high pressure chamber 4 is high, the pressure in the high pressure chamber 15 is also high, so that the sub spool valve 14 overcomes the spring force of the return spring 20 and slides. As a result, the drain passage 10 is throttled by the land portion 14b of the sub spool valve 14.

As described above, when the flow rate of the excess hydraulic fluid discharged to the drain passage 10 increases as the flow rate of the pump discharge hydraulic fluid flowing into the high pressure chamber 4 increases, the drain passage 10 and the spool valve on the drain passage 10 side are increased. A gap is formed between the end surface of the drain passage 3 and the end surface of the drain passage 3, and the variable passage 12 also forms a throttle portion in the drain passage 10. For this reason, the surplus hydraulic fluid flows in multiple stages before the opening of the drain passage 10 and the portion of the variable throttle 12. Thus, the pressure difference between the front and rear of each of the multi-stage throttle portions is a gradual decrease of the pressure difference before and after the conventional gap, so that the flow velocity from the spool accommodating hole 2 to the drain passage 10 is reduced. The kinetic energy of the fluid is reduced, and the erosion effect exerted on the wall surface of the drain passage 10 when the excess hydraulic fluid flows through the drain passage 10 is reduced.

Further, the movement of the sub-spool valve 14 (operation of the variable throttle 12) allows the drain passage 10 to communicate with the upstream side and the downstream side of the sub-spool valve 14 via the annular groove 14 a of the sub-spool valve 14. Since the state is adjusted according to the pressure of the excess hydraulic fluid in the high pressure chamber 4, the discharge flow rate of the excess hydraulic fluid discharged to the drain passage 10 becomes substantially the same as the conventional flow rate.

In this embodiment, a sub-spool housing hole 13 is formed in the casing 1, and a sub-spool valve 14 that throttle-controls the drain passage 10 is slidably housed in the sub-spool housing hole 13 so that a high pressure is achieved. The chamber 15 and the back pressure chamber 16 are separated from each other, a return spring 20 is provided while the pressure of the drain passage 10 is introduced into the back pressure chamber 16, and the pressure of the high pressure chamber 4 is introduced into the high pressure chamber 15. Although the diaphragm 12 has been described, the invention is not limited to this, and a variable diaphragm may be formed by a motor or a solenoid, and may be an external control that controls these by an external signal.

[0022]

[Effect of device]

 As described above, according to the present invention, the spool accommodating hole communicating with the discharge side of the pump, the spool valve accommodated in the spool accommodating hole, and the spool accommodating hole are opened and controlled by the spool valve. A drain passage, wherein the drain passage is opened by the sliding of the spool valve to discharge a part of the pump discharge working fluid to control the flow rate to the actuator. Since a variable throttle is provided in the drain passage downstream from the opening / closing opening, when the pressure in the high pressure chamber increases with an increase in the flow rate of the pump discharge hydraulic fluid, the drain passage and the end face of the spool valve on the drain passage side are increased. Since a gap is created in the drain passage and a throttle portion is also formed in the drain passage due to the variable throttle, the excess hydraulic fluid is squeezed in multiple stages before the opening of the drain passage and the variable throttle portion. It is possible. By the way, since the pressure difference between the front and rear of each throttle portion is reduced as compared with the conventional one, the flow velocity from the spool accommodating hole to the drain passage can be reduced to reduce the kinetic energy of the fluid. For this reason, it is possible to reduce the erosion effect exerted on the wall surface of the drain passage when the excess hydraulic fluid flows through the drain passage, thereby reducing the influence on the drain passage.

[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 housing hole 3 Spool valve 10 Drain passage 12 Variable throttle

Claims (1)

[Scope of utility model registration request] 1. A spool accommodating hole communicating with a discharge side of a pump, a spool valve accommodated in the spool accommodating hole, and a drain passage opened in the spool accommodating hole and controlled to be opened and closed by the spool valve. In a flow control valve that opens the drain passage by sliding the spool valve to discharge a part of the pump discharge hydraulic fluid to control the flow rate of the actuator, a drain downstream of the opening opened and closed by the spool valve. A flow control valve characterized in that a variable throttle is provided in the passage.