JPH02190683A - Pilot valve device - Google Patents

Abstract

PURPOSE:To reduce the compressive load to a piezoelectric element body by keeping a back chamber formed between a large-diameter piston and the piezoe lectric element body at the system pressure when amplifying the displacement of the large-diameter piston and conveying it to a small-diameter piston to open a seat face. CONSTITUTION:A small-diameter piston 11 is connected to the upper end section of a valve 3 via a fine-diameter rod 10, and the valve 3 opens or closes the seat face 6 of a valve chamber 2 via the vertical movement of the piston 11 slidably stored in a high-pressure chamber 5. A fluid guide hole 7 and a fluid discharge hole 8 are formed on a pilot valve device main body 1, and the fluid flowing into the chamber 5 through the hole 7 flows to the outside of the main body 1 through the hole 8. A compression chamber 9 is formed on the main body 1 at the upper section of the chamber 5, and a large-diameter piston 12 is slidably stored. A small-diameter projection 12a erected at the upper section of the piston 12 is slidably inserted into a bulkhead 19 formed on the main body 1. A back chamber 20 is formed with the back of the piston 12, the fluid is fed through a communicating port 21 communicated to the back chamber 20, and the back chamber 20 is kept at the fixed pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a pilot valve device used in an operating mechanism of a power circuit breaker using hydraulic pressure.

(Prior Art) As the capacity and ultra-high voltage of power transmission and substation systems increase, the performance of circuit breakers installed in these circuits has significantly improved, and demands for improved performance have also increased. Therefore, in recent years, many SF8 gas-insulated circuit breakers have been put into practical use, and a hydraulic operation method is mainly used as their operating mechanism. Hydraulic operating devices can handle higher pressures than those that use air pressure, so they can be made smaller, and the noise generated during shutoff operations is significantly reduced, and the operating fluid is incompressible. Therefore, it has advantages such as excellent responsiveness. Furthermore, from the viewpoint of power system protection, the shorter the fault clearing time of the power system, the higher the safety of the power system, so it is essential that circuit breakers operate at high speed. For this reason, the operational responsiveness of a valve that controls the hydraulic pressure acting on a piston used in a hydraulic operating device for operating a circuit breaker has been a problem.

By the way, the hydraulic system of the conventional circuit breaker hydraulic operating device is as follows:
It is constructed as shown in the hydraulic system diagram in FIG. That is, the operation part M consisting of the pistons P and S that opens and closes the circuit breaker CB is the main valve M whose opening and closing are controlled by the pilot valve Pv.
It is designed to be driven by V. In addition, the pilot valve Pv has two pilot valves pv for closing and shutting off.
1゜Pv2, and by energizing the electromagnetic solenoids CC and DC attached to each, pressure oil is supplied and discharged from the accumulator ACC and pump PF provided in the piping system into the main valve MV, and the operating part M is controlled. It looks like this. In addition, in order to improve the responsiveness of the main valve MV, a throttle D is provided between each flow path connecting the pilot valve PV Pv2 and the 1' accumulator ACC.

Furthermore, since the drive of a fluid control valve such as a pilot valve by a solenoid is determined by the ampere turns of the coil, it is necessary to increase the number of turns of the coil or the current value in order to obtain high output. However, in this case, problems arise such as a decrease in responsiveness due to an increase in inductance and burnout of the coil due to Joule heat. Therefore, if you try to obtain a high-speed operating valve using a solenoid drive system, you will inevitably have to pass a large current through a coil with a small number of turns, but there are many practical constraints, so the response speed of the valve can be made faster. There are limits to what you can do. In order to eliminate this drawback, conventionally,
A highly responsive pilot valve device that expands and contracts a piezoelectric element using a piezoelectric effect has been used.

That is, as shown in FIG. 5, a valve 3 is elastically held in a valve chamber 2 formed in a pilot valve device main body 1 by a spring 4 and is seated on a seat surface 6 of a valve seat of the valve chamber 2. . A small-diameter piston 11 is connected to the upper end of the valve 3 via a small-diameter rod 10. The small-diameter piston 11 is slidably accommodated in the high-pressure chamber 5, and the vertical movement of the small-diameter piston 11 moves the valve 3 into the seat of the valve chamber 2. The surface 6 can be opened and closed. Further, the pilot valve device body 1 is formed with a fluid introduction hole 7 and an outflow discharge hole 8 that communicate with a fluid supply source, and the fluid that flows into the high pressure chamber 5 from the fluid introduction hole 7 is passed through the fluid discharge hole 8. It is designed to flow out of the main body 1. A compression chamber 9 is formed in the main body 1 above the high pressure chamber 5, and a large diameter piston 12 is slidably accommodated in the compression chamber 9. The small diameter piston 11 is moved up and down by the large diameter piston 12 via the working fluid. Furthermore, a piezoelectric element body 13 made of a ceramic material laminated in an appropriate number is fixed on the back of the upper surface of the large-diameter piston 12, and the large-diameter piston 12 is expanded and contracted by the piezoelectric effect of the piezoelectric element body 13. It is designed to move up and down within the compression chamber 9. Note that this piezoelectric element body 13 is connected to a cover 1 fixed to the upper end of the main body 1.
It is attached to 4. Further, the high pressure chamber 5 and the compression chamber 9 are communicated through a communication hole 15, and a check valve 16 is provided in the middle of the communication hole 15. This check valve 1
Reference numeral 6 consists of a check valve body 16a and a spring 16b, and gaskets 18a and 18b are fitted into the sliding part of the small-diameter piston 11 and the passage 12 of fluid only from the high pressure chamber to the compression chamber 9, and the compression chamber This is to prevent the fluid inside 9 from leaking to the outside of the main body 1. Note that lead wires 17a and 17b are connected to the piezoelectric element 13 for applying voltage to its electrodes.

In the conventional pilot valve device configured in this way, first, when the valve 3 closes the seat surface 6 of the valve chamber 2, the inside of the high pressure chamber 9 is maintained at a high pressure state. When a voltage is applied to the piezoelectric element body 13 here, the piezoelectric element body 13 expands due to the piezoelectric effect, and the large diameter piston 1
2 is displaced downward. The displacement of the large diameter piston 12 is amplified and transmitted to the small diameter piston 11, and then the displacement of the small diameter piston 11 is transmitted to the valve 3 via the rod 10, which opens the seat surface 6 and allows the fluid in the high pressure chamber 5 to flow. It comes to be discharged to the outside of the main body 1. When the voltage application to the piezoelectric element body 13 is released, the piezoelectric element body 13 contracts and returns to its original state, and the valve 3 closes the seat surface again by the spring 4.

(Problem to be Solved by the Invention) However, in a pilot valve device using such a conventional piezoelectric element body, when the valve 3 is closed, the pressure in the compression chamber 9 is lower than the pressure in the high pressure chamber 5 controlled by the valve 3. is filled with a fluid having a pressure equal to .

Further, when the conventional pilot valve device is used as a high pressure system, the inside of the compression chamber 9 is also maintained at a high pressure state, and a large compression force is applied to the piezoelectric element body 13 via the large diameter piston 12.

This compressive force increases in proportion to the pressure-receiving area of the large-diameter piston 12, and sometimes exceeds the compressive breaking load of the piezoelectric element body 13. Furthermore, even if this compressive force is statically less than this breaking load, when the piezoelectric element body 13 operates, the compression chamber 9
They may also be dynamically subjected to high compressive forces, such as momentary oscillating pressure generated inside. Therefore, continuous operation of the valve device may lead to destruction of the piezoelectric element body. Furthermore, even if the piezoelectric element body 13 is fixed uniformly to the back surface of the large-diameter piston 12 with an adhesive or the like, pressure is not applied uniformly to the large-diameter piston 12, and the large-diameter piston 12 itself is slightly tilted. Sometimes. At this time, the piezoelectric element body 13 is subjected to an eccentric and highly concentrated load, and the piezoelectric element body 13 may eventually be destroyed by the bending load or the like. in this way,
Conventional pilot valve devices have many problems in terms of the mechanical strength and durability of the piezoelectric element body 13, and as a result, it has been difficult to obtain high operational reliability.

On the other hand, in order to avoid such problems, conventional pilot valve devices can only be used in low-pressure systems, resulting in the problem that the range of application of the pilot valve device is limited.

The present invention was made in order to solve these problems, and it is a piezoelectric material that is capable of high-speed switching, has high operational reliability such as durability, and is not limited to the pressure of the system to which it is applied. The object of the present invention is to provide a pilot valve device using an element body.

[Structure of the invention]

(Means for Solving the Problems) The present invention provides a pilot valve device that controls hydraulic pressure in a valve chamber by opening and closing a valve elastically held on a seat surface of the valve chamber by a spring, and a small diameter piston connected to the valve. a large-diameter piston with a small-diameter protrusion that drives the small-diameter piston via fluid pressure; a piezoelectric element body that is connected to the small-diameter protrusion and expands and contracts due to the piezoelectric effect to drive the large-diameter piston; and a valve. A high pressure chamber formed between the small diameter piston, a compression chamber filled with fluid and formed between the large diameter piston and the small diameter piston, and a partition wall formed between the large diameter piston and the piezoelectric element body. It consists of a back chamber formed between this partition wall and a large diameter piston, and communicates the high pressure chamber and compression chamber via a check valve, allowing fluid to flow only from the high pressure chamber to the compression chamber. The present invention also relates to a pie-rot valve device characterized in that a back chamber is communicated with a fluid supply source through a communication port.

(Function) In the pilot valve device of the present invention configured as described above, when a voltage is applied to the piezoelectric element body, the piezoelectric element body expands due to the piezoelectric effect, and the large diameter piston is driven downward in response. The downward displacement of the large-diameter piston is further amplified by the amplification effect in the compression chamber and transmitted to the small-diameter piston, and the valve is opened from the seat surface to discharge the controlled fluid in the high-pressure chamber to the outside. At this time, the inside of the back chamber is maintained at a stationary system pressure, so that the compressive load acting on the voltage element body via the large diameter piston is partially canceled out by the pressure inside the back chamber.

(Example) An example of the pilot valve device of the present invention will be described with reference to FIG.

As shown in FIG. 1, within a valve chamber 2 formed in a pilot valve device main body 1, a valve 3 is elastically held by a spring 4 and is seated on a seat surface 6 of a valve seat of the valve chamber 2. A small-diameter piston 11 is connected to the upper end of the valve 3 via a small-diameter rod 10. The small-diameter piston 11 is slidably accommodated in the high-pressure chamber 5, and the vertical movement (drive) of the small-diameter piston 11 moves the valve 3 into the valve chamber. The two seat surfaces 6 can be opened and closed. In addition, the pilot valve device main body 1 includes a fluid introduction hole 7 and an outflow discharge hole 8, respectively.
is formed, and the fluid flowing into the high pressure chamber 5 from the fluid introduction hole 7 flows out from the fluid discharge hole 8 to the outside of the main body l. A compression chamber 9 is located in the main body 1 above the high pressure chamber 5.
is formed, and a large diameter piston 12 is slidably accommodated in this compression chamber 9.

Further, a small diameter protrusion 12a is erected on the upper part of the large diameter piston 12, and a partition wall 1 having this small diameter protrusion 12a formed on the main body 1
It is slidably inserted into the through hole 9 through the packing 18. As a result, a back chamber 20 is formed between the back chamber 20 and the back surface of the large-diameter piston 12, and fluid is supplied through the communication port 21 communicating with this back chamber 20, so that the inside of the back chamber 20 is maintained at a constant pressure. . Furthermore, the communication port 21 communicates with, for example, the fluid introduction hole 7, the accumulator ACC, the pump PF, or the like.

Further, on the back of the upper surface of the small diameter protrusion 12a of the large diameter piston 12, a voltage element body 13 made of a ceramic material laminated in an appropriate number is fixed. A large diameter piston 12 is configured to move up and down (drive) within the compression chamber 9. Note that this piezoelectric element body 13 is attached to a cover 14 fixed to the upper end of the main body 1. Further, the high pressure chamber 5 and the compression chamber 9 are connected through a communication hole 15, and the communication hole 15
A check valve 16 is provided in the middle. This check valve 16 is made up of a check valve body 16a and a spring 16b, and serves as a check valve that allows fluid to pass only from the high pressure chamber 5 to the compression chamber 9.

Gaskets 18a and 18b are fitted into the sliding parts of the large-diameter piston 12 and the small-diameter piston 11, respectively, to prevent the fluid in the compression chamber 9 from leaking to the outside of the main body 1. Note that the piezoelectric element body 13 includes a lead wire 17a for applying a voltage to its electrode.

17b are connected.

In the pilot valve device of the embodiment of the present invention configured as described above, when the valve 3 closes the seat surface 6 of the valve chamber 2, the pressures in the compression chamber 9 and the back chamber 20 are maintained at the same pressure. There is. Therefore, the load generated when the pressure in the back chamber 20 acts on the pressure-receiving area on the back surface of the large-diameter piston 12 is the same as the load generated when the pressure in the compression chamber 9 acts on the pressure-receiving area on the front surface of the large-diameter piston 12. This acts to cancel out a part of the load acting on the voltage element body 13 via the piston 12 and its small diameter projection 12a.

Furthermore, since the compressive load applied to the piezoelectric element body 13 corresponds to the product of the previous pressure and the cross-sectional area of the small diameter protrusions 12 and 11,
It is possible to reduce the compressive load compared to conventional pilot valve devices. Here, when a voltage is applied to the piezoelectric element body 13, the piezoelectric element body 13 expands due to the piezoelectric effect.
Accordingly, the large diameter piston 12 is inserted through the small diameter projection 12a.
is displaced (driven) downward. The displacement of the large diameter piston 12 is amplified by the displacement amplification effect in the compression chamber 9 and transmitted to the small diameter piston 11.
0 to the valve 3, which opens the seat surface 6 and allows the controlled fluid in the high pressure chamber 5 to be discharged to the outside of the body 1. At this time, the inside of the back chamber 20 is maintained at the system pressure at rest, so the compression load acting on the piezoelectric element body 13 via the large-diameter piston 12 includes a transient pressure increase inside the compression chamber 9. will be added as a new load. Note that this pressure increase is caused by a time delay caused by a resistance force when the valve moves. Also,
In the embodiment of the present invention, the provision of the back chamber 20 does not affect the dynamic characteristics of the valve, such as a reduction in the displacement amplification effect within the compression chamber 9. Rather, since the load on the piezoelectric element body 13 when it is stationary is reduced, it becomes possible to increase the amount of displacement of the piezoelectric element body 13 compared to the conventional one. That is, as shown in FIG. 2, when the initial load is kept constant, the displacement p of the piezoelectric element body is the same as when no load is applied even if a certain amount of load is applied. However, when an excessively large load is applied, the amount of displacement decreases. Therefore, as shown in Fig. 2, if the initial load (F o) of the piezoelectric element body at rest is reduced, it will be lower than when used with a value close to the breaking load (Fo') as in the conventional pilot valve device. Piezoelectric element body 1
The displacement amount (N) of 3 can be increased CD:l'),
Therefore, the amount of displacement of the valve 3 is large, and the dynamic characteristics of the valve as a whole are improved.

Further, as another embodiment of the present invention, as shown in FIG. 3, the inside of the back chamber 20 is maintained at external pressure (atmospheric pressure),
It is also possible to reduce the compressive load applied to the piezoelectric element body 13 by disposing a disc spring 22 inside the piezoelectric element 0 so as to be in contact with the partition wall 19, so that the disc spring 22 always presses the large diameter piston 12 downward. It is. In this embodiment, the large diameter piston 1
2 (when displacing downward), this disc spring 22
is in the direction of being opened. However, since the amount of displacement is equivalent to a minute amount of displacement (several tens of am) of the piezoelectric element body 13, the pressing load of the disc spring 22 does not decrease.

〔Effect of the invention〕

According to the present invention, the displacement of the piezoelectric element that performs minute expansion and contraction operations due to the piezoelectric effect is transmitted to the large-diameter piston via the small-diameter protrusion, and the displacement of the large-diameter piston is amplified within the compression chamber and transmitted to the small-diameter piston. The valve was moved to open the seat surface (while maintaining the back chamber formed between the large diameter piston formed by the small diameter projection and the piezoelectric element body at the system pressure used for the pilot valve device. Therefore, the compressive load applied to the piezoelectric element body can be significantly reduced, and as a result, the mechanical strength and durability of the piezoelectric element body are improved, and the amount of displacement of the piezoelectric element body can be larger than that of conventional ones. The performance of the pilot valve device is greatly improved, and the pressure range of the system to which this pilot valve device is applied is not limited.Overall, a pilot valve device with high performance and high reliability is obtained.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a longitudinal cross-sectional view of a pyro-soto valve device according to an embodiment of the present invention, FIG. 2 is a diagram showing the relationship between piezoelectric displacement amount and applied load, and FIG. The figure is a longitudinal sectional view of a pilot valve device according to another embodiment of the present invention, FIG. 4 is a hydraulic system diagram of a circuit breaker hydraulic system to which the pilot valve device is applied, and FIG. 5 is a longitudinal sectional view of a conventional pilot valve device. Show the front view. 1...Pilot valve device main body, 2...Valve chamber, 3...
・Valve, 4... Spring, 5... High pressure chamber, 9... Compression chamber, 11... Small diameter piston, 12... Large diameter piston,
13... Piezoelectric element, 14... Cover, 15... Communication hole, 16... Check valve, 19... Partition wall, 20...
...Back chamber, 21...Communication port.

Claims (1)

[Claims] In a pilot valve device that controls hydraulic pressure in a valve chamber by opening and closing a valve that is elastically held on the seat surface of the valve chamber by a spring, a small-diameter piston connected to the valve and this small-diameter piston are driven via fluid pressure. a large-diameter piston having a small-diameter protrusion erected thereon; a piezoelectric element body connected to the small-diameter protrusion and configured to expand and contract due to a piezoelectric effect to drive the large-diameter piston; and a piezoelectric element body formed between the valve and the small-diameter piston. a high-pressure chamber; a compression chamber formed between the large-diameter piston and the small-diameter piston and containing a fluid; a partition wall formed between the large-diameter piston and the piezoelectric element body; and a back chamber formed between the piston and the high pressure chamber and the compression chamber through a check valve to allow fluid to flow only from the high pressure chamber to the compression chamber. A pilot valve device characterized in that it communicates with a fluid supply source through a communication port.