JPH0527752Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The invention is applied to hydraulic machinery, automobile parts (power steering, brakes, suspension, transmission, etc.), brakes for railway vehicles, construction machinery, etc. This invention relates to a pressure control valve that obtains a controlled hydraulic pressure according to the electromagnetic force of a solenoid.

(Prior art) As a conventional pressure control valve, for example,
The one described in Publication No. 59376 is known.

This conventional pressure control valve includes a valve spool that is slidably installed in a valve hole of a valve body and controls output hydraulic pressure, and a valve spool that is installed at one end of the valve spool to direct the valve spool in the direction of increasing the output hydraulic pressure. a solenoid for pressing the valve spool, a back chamber formed facing the other end of the valve spool, and a solenoid formed in the valve spool with one end opening into the back chamber;
a communication hole whose other end is opened to the output hydraulic pressure generating part;
The communication hole had an orifice formed therein.

Therefore, when the valve spool slides toward the back chamber due to the suction force of the solenoid, the volume of the back chamber changes, and the working fluid corresponding to this volume change flows through the communication hole.
When the hydraulic fluid flowing through the communication hole passes through the orifice, a damping force is generated, and the vibration of the valve spool is damped by this damping force.

(Problems to be Solved by the Invention) However, in such a conventional pressure control valve, since the orifice is fixed, there are the following problems.

That is, in a solenoid, the attraction force increases gradually or rapidly depending on the applied control current, and therefore the valve spool is slid slowly or suddenly.

In this way, when the valve spool slides rapidly, the volume of the back chamber changes rapidly due to the sliding of the valve spool, causing a rapid flow of working fluid in the communication hole, and the damping that occurs in the orifice. The force becomes larger than necessary. This excessive damping force interferes with the sliding movement of the valve spool, causing a delay in the sliding movement, resulting in a problem in that responsiveness deteriorates.

(Means for Solving the Problems) The present invention solves the above-mentioned problems and provides a pressure control valve that can suppress vibration without sacrificing responsiveness when the valve spool starts sliding. It is intended to.

To achieve this objective, the present invention includes a valve spool that is slidable in the valve hole of the valve body and is provided so as to be pressed by the solenoid to control the output hydraulic pressure, and a valve spool that is installed at both ends of the valve hole. a back chamber formed to allow sliding and held at drain pressure; and a pressure chamber hole bored in the valve spool in the axial direction from the end opposite to where the solenoid is provided. , an orifice that is slidably installed in the pressure chamber hole, forms a pressure chamber with the inner peripheral surface of the pressure chamber hole, and has an orifice hole that communicates the pressure chamber with the back chamber; a first spring provided in the back chamber to elastically support the orifice piston in the piston sliding direction with respect to the valve body; and a first spring provided in the pressure chamber to support the valve spool in the spool sliding direction with respect to the orifice piston. a second spring for elastic support, and the first spring is set to a predetermined spring constant higher than that of the second spring.

(Function) (a) When the solenoid suction force gradually increases When the solenoid suction force gradually increases, the valve spool slides gently in the pressure increasing direction.

The sliding direction end of this valve spool is connected to the second
The spring, orifice piston, and first spring are supported by the valve body in this order, and when the valve spool slowly presses them as they slide, only the second spring shortens due to the difference in spring constant, causing the valve to collapse. The relative movement between the spool and the orifice piston reduces the volume of the pressure chamber.

Due to this change in the volume of the pressure chamber, the working fluid flows out into the back chamber through the orifice hole, the pressure within the pressure chamber 6 increases, a damping force is generated, and the vibration of the valve spool is damped.

In addition, since the valve spool slides slowly at this time, the volume change in the pressure chamber is also gradual, so the working fluid in the pressure chamber flows smoothly from the orifice hole to the back chamber, and the pressure in the pressure chamber is not too high. No. Therefore, the force that the orifice piston receives is low, the first spring that supports the orifice piston is not shortened much, and the amount of displacement of the orifice piston is small.

That is, when the suction force of the solenoid increases gradually, the orifice piston hardly moves, and the same damping effect as in the case of a fixed orifice can be obtained.

(b) When the solenoid suction force suddenly increases When the solenoid suction force increases rapidly, the valve spool also slides rapidly in the pressure increasing direction.

Therefore, the valve spool suddenly presses the second spring at the end, the orifice piston, and the first spring, causing a sudden change in the volume of the pressure chamber, which prevents the hydraulic fluid from flowing out smoothly at the orifice hole. , the pressure in the pressure chamber rises rapidly and a large damping force occurs.

In this way, when the internal pressure of the pressure chamber suddenly increases and a large damping force is generated on the orifice, a pressing force of more than a predetermined value acts on the orifice piston that receives this pressure, and the first spring is also shortened and the orifice piston is displaced.

This displacement of the orifice piston prevents the internal pressure of the pressure chamber from increasing to a predetermined pressure or higher, and the sliding of the valve spool is not suppressed.

That is, compared to a fixed orifice, the damping force on the valve spool is reduced by the movement of the orifice piston and the prevention of internal pressure rise, and the responsiveness of the valve spool is improved.

(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.

The figure is a cross-sectional view showing a pressure control valve A according to an embodiment of the present invention, and this pressure control valve A receives hydraulic pressure from a pump (not shown) in a hydraulic pressure control circuit for operating an actuator (not shown). , a control pressure circuit S that outputs control hydraulic pressure to the actuator, and a drain circuit D that drains the hydraulic pressure to a drain tank (not shown).

In the figure, 1 indicates a valve body forming the main body of this pressure control valve A, and the valve body 1 is
A valve hole 11 is bored, and a first back chamber 13 communicating with a drain hole 12 is provided at both ends of the valve hole 11.
and a second back chamber 14 are provided. Note that the drain hole is connected to a drain circuit D.

A valve spool 2 is slidably housed in the valve hole 11 coaxially with the valve hole 11, and the valve hole 11 also has a pump pressure port 111, a drain port 112, a control pressure port 113, A feedback port 114 is formed.

On the other hand, the valve spool 2 has a pump-side land 21, a drain-side land 22, and a feedback land 23 formed on its outer circumference, and also has a feedback hole 24 in its axial center from one end to the vicinity of the other end. is drilled.

That is, both the lands 21 and 22 on the pump side and the drain side of the valve spool 2 are connected to the pump pressure port 111.
and the drain port 112, and the valve spool 2 is slidably connected to the control pressure port 113 and both ports 111, 112.
By selectively communicating with control pressure port 1
It is configured to be able to control the hydraulic pressure of 13.

Further, the control pressure port 113 and the feedback port 114 are connected to the feedback hole 2.
4, and the drain side land 2
Due to the difference in pressure receiving area based on the diameter difference between the valve spool 2 and the feedback land 23 (the feedback land 23 is formed with a larger diameter), the feedback pressure is applied to the valve spool 2 in the left direction in the figure. That is, it is configured to act in a direction opposite to the pressing force of the solenoid 3, which will be described later.

A solenoid 3 is provided at one end of the valve spool 2 (left side in the figure). The solenoid 3 slides the plunger 31 by the suction force generated in response to the control current, and the pressing force of the plunger 31 slides the valve spool 2 in the right direction in the figure to increase the control fluid pressure. It is something that makes you

A pressure chamber hole 4 having a larger diameter than the feedback hole 24 is formed at the other end of the valve spool 2 (on the right side in the figure). An orifice piston 5 is slidably provided in the orifice piston 5, and a pressure chamber 6 is formed by the inner peripheral surface of the pressure chamber hole 4 and the orifice piston 5.

The orifice piston 5 has a cylindrical sliding part 51 that slides against the pressure chamber hole 4, and a flange-like support flange part that closes one end of the sliding part 51 and forms the wall of the pressure chamber 6. 52, and an orifice hole 53 is formed in the support flange portion 52 so as to communicate the pressure chamber 6 and the second back chamber 14.

The orifice piston 5 is elastically supported in the sliding direction of the piston by a first spring 7 whose spring constant is set high with respect to the end cap 15 of the valve body 1. A second spring 8 is provided in the chamber 6 and has a low spring constant.
The valve spool 2 is supported in the spool sliding direction.

That is, the other end (left side in the figure) of the valve spool 2 is elastically supported by the second spring 8 on the orifice piston 5, which is elastically supported by the first spring 7.

The first spring 7 is set to a spring constant of such a height that it is hardly shortened when normal damping force is generated in the orifice piston 5, but is only shortened to some extent when a large damping force is generated.

Next, the operation of the embodiment will be explained.

First, the effect when the suction force of the solenoid 3 is gradually increased will be explained.

When a small current or low frequency current is passed through solenoid 3,
The suction force of the solenoid 3 gradually increases, thereby gently sliding the valve spool 2 in the pressure increasing direction (rightward in the figure).

The end of the valve spool 2 in the sliding direction is supported by the end cap 15 of the valve body 1 in the order of the second spring 8, the orifice piston 5, and the first spring 7. When these are pressed slowly, the second spring 8 having a low spring constant is shortened, and this causes relative movement between the valve spool 2 and the orifice piston 3, thereby reducing the volume of the pressure chamber 6.

The volume change Q of the pressure chamber 6 is as follows, where A1 is the pressure receiving area of the pressure chamber 6 on the valve spool 2 side, and v is the sliding speed of the valve spool 2.

Due to this change in the volume of the pressure chamber 6, the working fluid flows out into the second back chamber 14 through the orifice hole 53, and due to the outflow resistance at this time, the pressure in the pressure chamber 6 increases, and this pressure causes the valve to close. Spool 2
A damping force is generated, and the vibration of the valve spool 2 is suppressed.

In addition, the flow rate of the working fluid passing through this orifice 53
Q ₀ is the flow path coefficient, C ₀ is the orifice cross-sectional area, and A ₀ is the orifice cross-sectional area.
When the pressure in the pressure chamber 6 is P ₀ and the density of the fluid is ρ, Q ₀ =C ₀ ·A ₀ √2 ₀ . . . .

Also, from the continuity equation, Q = Q ₀ ... holds, so according to the three equations above, the flow rate Q occurs with the speed v of the valve spool 2, and the pressure chamber 6
A pressure of P ₀ is generated. Due to this pressure P ₀ , a damping force F of F=P ₀ ·A1 . . . acts toward the left in the figure to prevent the valve spool 2 from sliding.

Furthermore, since the valve spool 2 slides slowly at this time, the volume change Q of the pressure chamber 6 is also gradual, and therefore the working fluid in the pressure chamber 6 flows out smoothly from the orifice hole 53 to the second back chamber 14. and pressure chamber 6
The pressure P ₀ does not become very high. Therefore, the force that the orifice piston 5 receives is low, the first spring 7 that supports the orifice piston 5 is not shortened much, and the amount of displacement of the orifice piston 5 is small.

The force acting around this orifice piston 5 is
Assuming that the spring constant of the first spring 7 is k1, the spring constant of the second spring 8 is k2, the amount of deflection of the first spring 7 is x1, and the amount of deflection of the second spring 8 is x2, k1・x1=P ₀・A1+k2・Given by x2...

That is, when the suction force of the solenoid 3 increases gradually, the orifice piston 5 hardly moves, and the same damping effect as in the case of a fixed orifice can be obtained.

(b) When the solenoid suction force suddenly increases When a large current or high frequency current is passed through the solenoid 3 and the suction force of the solenoid 3 suddenly increases, the valve spool 2 also slides rapidly in the pressure increasing direction.

Therefore, the valve spool 2 suddenly presses the second spring 8, the orifice piston 5, and the first spring 7 at the end, causing a sudden change in the volume of the pressure chamber 6, causing the hydraulic fluid in the pressure chamber 6 to flow into the orifice. The water rapidly tries to flow out from the hole 53 into the second back chamber 14, where large resistance is generated and the pressure in the pressure chamber 6 rises rapidly. This tends to generate a large damping force.

When the internal pressure of the pressure chamber 6 rises rapidly and a large damping force is generated, a pressing force of more than a predetermined value acts on the orifice piston 5 that receives this pressure.
Due to this pressing force above a predetermined value, the first
Piston 8 is shortened and orifice piston 5 is displaced.

This displacement of the orifice piston 5 prevents the internal pressure in the pressure chamber 6 from rising above a predetermined level, and the sliding of the valve spool 2 is not suppressed.

That is, the damping force applied to the valve spool 2 is reduced compared to a fixed orifice to the extent that the orifice piston 5 is moved and the internal pressure of the pressure chamber 6 is prevented from rising, and the responsiveness of the valve spool 2 is improved accordingly.

In this way, in the example device, when the suction force of the solenoid suddenly increases, the orifice piston is displaced and the damping force does not increase beyond a predetermined level, ensuring the responsiveness of the valve spool. It has the characteristic that vibration can be suppressed without sacrificing responsiveness at the start of sliding.

Although the embodiment of the present invention has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment. For example, in the embodiment, the present invention is applied to a pressure control valve of a type that receives feedback pressure. shown, but is not limited to this.

(Effects of the Invention) As explained above, in the pressure control valve of the present invention, when the suction force of the solenoid increases gradually, a damping force similar to that of a fixed orifice can be obtained, but when the suction force of the solenoid increases suddenly, the orifice piston is displaced so that the damping force does not increase above a predetermined level, thereby ensuring the responsiveness of the valve spool, and providing the effect of vibration control without sacrificing the responsiveness of the valve spool when it starts to slide.

[Brief explanation of the drawing]

The figure is a sectional view showing a pressure control valve according to an embodiment of the present invention. 1... Valve body, 2... Valve spool,
3... Solenoid, 5... Orifice piston,
6... Pressure chamber, 7... First spring, 8... Second spring, 11... Valve hole, 14... Second
Back chamber (back chamber).

Claims (1)

[Scope of Claim for Utility Model Registration] A valve spool that is slidable in a valve hole of a valve body and is provided so as to be pressed by a solenoid to control output hydraulic pressure; a back chamber formed to accommodate and maintain a drain pressure; a pressure chamber hole drilled axially in the valve spool from an end opposite to that in which the solenoid is provided; an orifice piston that is slidably installed in the chamber hole, forms a pressure chamber with the inner peripheral surface of the pressure chamber hole, and has an orifice hole that communicates the pressure chamber with the back chamber; a first spring provided in the back chamber to elastically support the orifice piston in the piston sliding direction with respect to the valve body; and a first spring provided in the pressure chamber to elastically support the valve spool in the spool sliding direction with respect to the orifice piston. A pressure control valve comprising: a second spring, wherein the first spring is set to a predetermined spring constant higher than that of the second spring.