JPH01304628A - Pilot valve device - Google Patents

Abstract

PURPOSE:To enable high speed changeover so as to improve the reliability of operation by driving a valve through increase in displacement of piezoelectric element body by use of a fluid sealed in a compression chamber between a large and small dia. pistons, and communicating the compression chamber with a valve chamber through a check valve. CONSTITUTION:Under a condition that a sheet face 6 is closed by a ball valve 3, the inside of valve chamber and compression chamber 9 are maintained in the same high pressure conditions. When a voltage is applied to a compression element 13, the element 13 elongates due to an electrostriction effect and a large dia. piston 12 is displaced downwards in accordance with the elongation thereof. The displacement is converted to that of a small dia. piston 11 is amplified based on the continuity of liquid in the compression chamber. The displacement of prison 11 is conveyed to a ball valve 13 through a rod 10 to open a sheet face 6, and the fluid in the chamber 2 is discharged to a fluid discharge port 8. When a voltage to the element 13 is released, the element 13 is shrunk to the original condition, and the valve 3 closes the face 6 by means of a spring 4.

Description

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

(Prior art) In recent years, with the realization of larger capacity transmission and substation systems and ultra-high voltage, there has been a remarkable improvement in the performance of circuit breakers installed in these circuits, and there has been a demand for improved performance. is big. For this reason, many SF and gas-insulated circuit breakers have recently been put into practical use, and a hydraulic operation method is mainly used as their operating mechanism. Hydraulic operating devices have advantages such as being able to increase the pressure more easily than pneumatic pressure, making them more compact, significantly reducing noise during shutoff operations, and providing excellent responsiveness due to the incompressibility of hydraulic pressure. There is.

Furthermore, in view of the role of power system protection, the shorter the fault clearing time of the power system, the higher its safety, and therefore the circuit breaker must operate at high speed.

Therefore, the operational responsiveness of the valve that controls the hydraulic pressure of the piston of the hydraulic operating device that operates the circuit breaker becomes a problem.

The hydraulic operating device for the circuit breaker is constructed as a system as schematically shown in FIG. That is, a piston P that opens and closes the circuit breaker CB,
An operating section M consisting of a cylinder S is driven by hydraulic pressure from a main valve MV controlled by a pilot valve Pv. The pilot valve Pv has two pilot valves, one for closing and one for closing, and pressure oil is supplied and discharged into the main valve MV by an accumulator AL and a pump in the piping system by the activation of the respective electromagnetic solenoids CC and DC. By doing so, the operating section M is controlled. In order to improve the responsiveness of the main valve MV, a throttle D is provided in the flow path connecting both pilot valves PV to the accumulator AL.

(Problems to be Solved by the Invention) Conventionally, electrode drive using a solenoid has been adopted for driving a liquid control valve using an electric signal. However, in the case of solenoid drive, the driving force is determined by the ampere turns of the coil, so in order to obtain high output it is necessary to increase the number of turns in the coil or increase the current value. In this case, there are problems such as a decrease in responsiveness due to an increase in inductance and burnout of the coil due to Joule heat. Therefore, in order to obtain a high-speed valve using a solenoid drive system, a method is inevitably used in which a large current is passed through a coil with a small number of turns, but there are many practical constraints, so there is a limit to the response speed.

The present invention has been made in order to eliminate the above-mentioned drawbacks, and an object of the present invention is to provide a pilot valve device that is capable of high-speed switching and has high operational reliability.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a large-diameter piston driven by an extremely quick-response piezoelectric element body that expands and contracts by electrostrictive effect, and a large-diameter piston that It is equipped with a valve connected to a driven small diameter piston, and a check valve is used to check the valve chamber, where fluid pressure is maintained and discharged by opening and closing the valve, and the compression chamber, in which fluid is sealed between the large diameter and small diameter pistons. It is communicated through.

(Function) In the present invention, the large-diameter piston is driven by applying voltage to the piezoelectric element body, and its displacement is based on the continuity of the fluid sealed in the compression chamber between the large-diameter and small-diameter pistons. The valve chamber seat surface is opened by the amplified displacement, and when the voltage applied to the piezoelectric element body is released, the seat surface is opened by the action of the compression spring provided in the valve chamber. It is formed to close. Furthermore, even if the fluid in the compression chamber leaks due to the action of the check valve, the fluid pressure can be replenished, and the fluid pressure is maintained at a high pressure equal to that in the valve chamber, that is, inside the system. can eliminate the negative effects of

(Example) The present invention will be explained according to an example shown in FIG. A ball valve 3 is elastically held within the valve chamber 2 of the pilot valve device 1 by a spring 4 and a stopper 5, and is pressed against a seat surface 6 of the valve chamber 2. A small-diameter piston 11 is connected to the ball valve 3 via a rond 10, and the seat surface 6 is opened and closed by vertical movement of the small-diameter piston 11. Further, a fluid introduction hole 7 and a fluid discharge hole 8 are formed in the pilot valve device 1, and the fluid introduction hole 7 is connected to the valve chamber 2.
The fluid that has flowed into the tank 8a flows out through the discharge hole 8 into the tank 8a. The small diameter piston 11 is driven via fluid by a large diameter piston 12 that slides within a compression chamber 9 provided in the pilot valve device 1 . A suitable number of laminated ceramic piezoelectric elements 13 are provided on the back of the large diameter piston 12, and the compression chamber 9 is expanded and contracted by the electrostrictive effect of the ceramic piezoelectric elements 13.
It is designed to move up and down inside. The piezoelectric element 13 is attached to a cover 14 fixed to the top of the pilot valve device 1. Further, the valve chamber 2 and the compression chamber 9 are communicated with each other through a communication hole 15, and a check valve 16 is provided in the middle.

The check valve 16 consists of a check valve body 16a and a spring 16b, and is configured so that fluid passes only in the direction from the valve chamber 2 to the compression chamber 9, and is closed in the opposite direction. Furthermore, the sliding parts of the large-diameter piston 12 and the small-diameter piston 11 have packings 18.
a and 18b are provided to prevent the fluid in the compression chamber 9 from leaking to the outside. In addition, 17a.

17b is a lead wire for applying voltage to the electrode of the piezoelectric element 13. In addition, the cross-sectional area of the small diameter piston 11 is 81
, the cross-sectional area of the sheet surface 6 is S2, and the cross-sectional area of the sheet surface 6 is S2.
Then, as a condition for reliably closing the ball valve 3 to the seat surface 6, S≦82 is required.

Next, the operation of this embodiment will be explained. When the ball valve 3 closes the seat surface 6, the insides of the valve chamber 2 and the compression chamber 9 are maintained at the same high pressure state.

When a voltage is applied to the piezoelectric element 13, the piezoelectric element 13 expands due to its electrostrictive effect, and the large diameter piston 12 also displaces downward accordingly. The displacement at this time is usually several tens of μm.
Although this is extremely small, it is converted into a displacement of the small diameter piston 11 that is amplified based on the continuity of the fluid within the compression chamber 9. If the cross-sectional area of the large-diameter piston is 83, the displacement of the large-diameter piston 12 will be amplified by a factor of S,/31. The amplified displacement of the small diameter piston 11 is transmitted to the ball valve 3 via the rod 10, opens the seat surface 6, and the fluid in the valve chamber 2 is discharged into the tank 8a. When the voltage applied to the piezoelectric element 13 is released, the piezoelectric element 13 contracts to its original state, and the ball valve 3 closes the seat surface 6 by the spring 4.

FIG. 2 shows the characteristics when this pilot valve is used in the circuit breaker hydraulic operating device system shown in FIG. 3. This figure is a timing chart regarding the voltage applied to the piezoelectric element 13, the pressure in the compression chamber 9, the displacement of the ball valve 3, and the pressure in the valve chamber 2. When a voltage is applied to the piezoelectric element 13, the pressure inside the compression chamber increases due to its displacement, but at this time, leakage of the internal fluid is prevented by the action of the check valve 16 and the packings 18a and 18b. The ball valve 3 begins to open when a pressure increase that overcomes the resistance force acting in the closing direction of the ball valve 3, such as the force of the spring 4, is obtained. With 5i4s2, no hydraulic pressure is applied as a drag force when the valve is opened, so the valve can respond quickly. Since the throttle D is provided in front of the valve chamber 2, the pressure within the valve chamber 2 decreases as the valve opens. At this time, since the small diameter piston 11 moves by the volume of movement of the large diameter piston 12, the pressure in the compression chamber returns to almost its initial state. During voltage application, the force in the valve opening direction is strong, so the valve is held in the open position. When the application is removed, the pressure in the compression chamber decreases as the piezoelectric element contracts, and when the force in the valve closing direction becomes strong, the ball valve performs a closing operation.

At this time, the pressure in the valve chamber 2 and compression chamber 9 returns to its original state.

In this state, even if the fluid in the compressor leaks, hydraulic pressure is supplied from within the valve chamber 2 by the action of the check valve 16, and the pressure is always maintained at a high level. In addition, since the compression chamber is maintained at a high pressure, there is little delay in response when the valve is opened due to the influence of compressible fluid such as air being mixed in. Furthermore, since the bulk elastic modulus of the fluid is higher than when the pressure is low, the pressure in the compression chamber can be efficiently increased during operation, and high-speed operation is possible. Note that this pilot valve device can be applied not only to circuit breakers but also to other hydraulic devices.

〔Effect of the invention〕

As explained above, according to the present invention, the displacement of the piezoelectric element body, which responds extremely quickly, is amplified by the fluid sealed in the compression chamber between the large and small diameter pistons to drive the valve, and the compression chamber and the valve chamber are separated. Since the valves are communicated through a check valve, it is possible to provide a highly reliable pilot valve device that is capable of high-speed response and can prevent a decrease in responsiveness due to fluid leaks in the compression chamber. can.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a pilot valve device showing an embodiment of the present invention, Fig. 2 is an operating characteristic diagram of the pilot valve device shown in Fig. 1, and Fig. 3 is a cross-sectional view of the pilot valve device shown in Fig. 1. It is a hydraulic system diagram of a general circuit breaker hydraulic system to which it is applied. 1...Pilot valve device, 2...Valve chamber, 3...Ball valve, 4...Spring, 5...Stopper,
6... Seat surface, 7... Fluid introduction hole,
8...Fluid discharge hole, 9...Compression chamber, l
O...Rod, 11...Small diameter piston, 12...
Large diameter piston, 13... piezoelectric element, 14...
·cover. 15...Communication hole, 16...Check valve,
16a...Check valve body, 16b...Spring, 1
7a, 17b = lead wire, 18a, 18b - packing. Agent Patent Attorney Noriyuki Ken Yudo Daishimaru Ken Figure 1 Figure 2

Claims (1)

[Claims] In a valve device that controls hydraulic pressure in a valve chamber by opening and closing operations of a valve elastically held by a spring, a small-diameter piston connected to the valve, a large-diameter piston that drives the small-diameter piston via fluid pressure, The large-diameter piston is provided with a piezoelectric element that drives the large-diameter piston by an expansion/contraction motion caused by an electrostrictive effect, and the valve chamber is communicated with a compression chamber in which fluid is sealed between the large-diameter piston and the small-diameter piston via a check valve. A pilot valve device that allows fluid to flow only in the direction from the valve chamber to the compression chamber, and is characterized in that a packing is provided on each sliding portion of the large-diameter piston and the small-diameter piston.