JPH03213780A - Direction control valve using piezoelectric element and driving thereof - Google Patents

Abstract

PURPOSE:To reduce the load applied on a piezoelectric element, prevent the leak of fluid pressure, secure the stability of operation, and prolong the service life, by installing the piezoelectric element which is one-side-shifted by the application of the pulse voltage. CONSTITUTION:A direction control valve is equipped with an operating member which is shifted by each fluid pressure of the working fluid chambers 12a and 12b and a main shaft 9 on which valve bodies 10a - 10d for restricting the flow passage through the displacement of the operating members are formed. This control valve is equipped with piezoelectric elements 16a and 16b which are one-side-shifted, by the application of the pulse voltage, in the pilot fluid chambers 14a and 14b which communicating to the working fluid chambers 12a and 12b, while the valve is also equipped with and pilot valve bodies 17a and 17b fixed on each main plane at the shifting edge. An under-pressure fluid flow-in passage 18 and a fluid pressure bleed holes 15a and 15b communicate to the pilot fluid chambers 14a and 14b, and the under-pressure fluid flow-in passage 18 is opened to one side of the pilot valve bodies 17a and 17b, when the piezoelectric elements 16a and 16b shift, and fluid bleed holes 15a and 15b are put into closed state by the other side of the pilot valve bodies 17a and 17b.

Description

[Detailed Description of the Invention] : Industrial Application Field] The present invention relates to a directional control valve using a piezoelectric element, and in particular, the load on the piezoelectric element can be reduced, and operation stability and longevity can be improved. The present invention relates to a technique that is effective when applied to a directional control valve and a method for driving the same, which enable switching by reliable operation.

[Conventional technology]

Some directional control valves that control the flow of fluid pressure have a structure that utilizes the displacement of a piezoelectric element. It has a structure that includes a piezoelectric element that opens and closes by opening and closing, and a valve body that is actuated via an actuating member to switch the flow path when the fluid pressure in the actuating fluid chamber increases.

Further, as methods for driving the piezoelectric element, there are a method in which one side is displaced by applying a continuous voltage, a method in which the piezoelectric element is alternately displaced by application of an alternating voltage, and the like.

For example, when a piezoelectric element is driven by applying a continuous voltage to displace it on one side, voltage is always applied to one side of the bimorph structure in the opposite direction to the polarization direction, and when the piezoelectric element is displaced toward the -blade side, the operating fluid chamber opens. The inlet channel is opened and closed.

[Problems to be Solved by the Invention] However, in the directional control valve using the piezoelectric element driving method as described above, voltage is always applied to one side of the bimorph structure that constitutes the piezoelectric element in the opposite direction to the polarization direction. Furthermore, if a continuous voltage is applied for a long time, polarization deterioration occurs in the piezoelectric element having a bimorph structure due to a polarization phenomenon.

Furthermore, since the direction of displacement of the piezoelectric element is limited to one side, similarly, if a continuous voltage is applied for a long time, the piezoelectric element will be deformed due to the creep phenomenon. In particular, piezoelectric elements are prone to such problems because their mechanical strength is relatively low.

In addition, when the actuating member is displaced or returned in the opposite direction due to an increase in fluid pressure, the switching speed of the actuating member is greatly influenced by the position of the fluid pressure bleed hole, for example, when the fluid pressure increases, the fluid pressure flows out. If a bleed hole is opened at a certain location, there is a problem in that the flow of fluid pressure cannot be quickly switched.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a piezoelectric element that can reduce the load on the piezoelectric element by driving by applying a pulse voltage, and that can prevent fluid pressure leakage, provide stable operation, and extend the life of the piezoelectric element. An object of the present invention is to provide a directional control valve and a method for driving the same.

Another object of the present invention is to provide a directional control valve using a piezoelectric element and a method for driving the same, which enable reliable and actual switching by adjusting the position of a fluid pressure bleed hole and a switch corresponding to each piezoelectric element. It is about providing.

5 Means for Solving Problems] A directional control valve using a piezoelectric element of the present invention includes an actuation member that is displaced by fluid pressure in an actuation fluid chamber, and a valve body that controls a flow path by the displacement of the actuation member. A directional control valve having a main shaft formed therein, a piezoelectric element that is displaced on one side by application of a pulse voltage in a pilot fluid chamber that communicates with the actuation fluid chamber, and each main surface of a displacement end of the piezoelectric element. a pilot valve body fixed to the pilot valve body, a fluid pressure inflow path and a fluid pressure bleed hole communicate with the pilot fluid chamber, and when the piezoelectric element is displaced, the fluid pressure inflow path is connected to one side of the pilot valve body. The hydraulic bleed hole is brought into the open state by the other side of the pilot valve body, and the fluid pressure bleed hole is brought into the closed state by the other side of the pilot valve body.

Further, a method for driving a directional control valve using a piezoelectric element of the present invention includes a first actuating member and a second actuating member that are displaced by fluid pressure in first and second actuating fluid chambers; and a main shaft in which a valve body is formed to control the flow path in response to the displacement of the second actuating member, the double pilot type directional control valve comprising: A first piezoelectric element and a second piezoelectric element that are displaced on one side by application of a pulse voltage in the first and second pilot fluid chambers that communicate with each other; and a second piezoelectric element that applies a pulse voltage to the first and second piezoelectric elements. 1 switch and a second switch, the first switch displaces the first piezoelectric element, the second switch displaces the second piezoelectric element, and the first and second piezoelectric elements are displaced. The first fluid pressure inflow path and the second fluid pressure inflow path communicating with the second pilot fluid chamber can be opened and closed independently.

[Effect]

According to the above-mentioned directional control valve using a piezoelectric element, there is a piezoelectric element that is displaced on one side by the application of a pulse voltage in the pyro-fluid chamber, which communicates with the actuating fluid chamber, and each main body at the displacement end of the piezoelectric element. A fluid pressure inflow path and a fluid pressure bleed hole communicate with the pilot fluid chamber, and when the piezoelectric element is displaced, the fluid pressure inflow path connects to one side of the pilot valve body. The piezoelectric element to which the pulse voltage is applied is displaced on one side by a time equal to the pulse width, and the fluid pressure bleed hole is closed by the other side of the pilot valve body. Since the normal state is restored at a time other than the pulse width, voltage is not continuously applied to the bimorph piezoelectric element for a long time. Thereby, it is possible to obtain a directional control valve using a piezoelectric element that prevents leakage of fluid pressure, has stable operation, and has a long life.

In addition, in this case, the fluid pressure inflow path communicating with the pilot fluid chamber is opened when the piezoelectric element is displaced, and the fluid pressure bleed hole is closed, so that the fluid pressure is Since the bleed hole can be closed, it is possible to prevent fluid pressure from leaking in the fluid chamber due to an increase in fluid pressure.

Furthermore, according to the method for driving a directional control valve using the piezoelectric element described above, by applying a pulse voltage in the first and second pilot fluid chambers that communicate with the first and second actuating fluid chambers, A double pilot type directional control comprising a first piezoelectric element and a second piezoelectric element that are displaced on one side, and a first switch and a second switch that apply a pulse voltage to the first and second piezoelectric elements. In the valve, the first
The switch displaces the first piezoelectric element and displaces the second piezoelectric element.
The switch displaces the second piezoelectric element and independently opens and closes the first fluid pressure inflow path and the second fluid pressure inflow path that communicate with the first and second pilot fluid chambers. Switching can be performed after confirming the operation of the main shaft that is displaced via the second actuating member. Thereby, it is possible to obtain a method of driving a directional control valve in which the main shaft is reliably operated and fluid pressure can be reliably controlled.

〔Example〕

FIG. 1 is a cross-sectional view of a directional control valve using a piezoelectric element, which is an embodiment of the present invention, and FIG. 2 is a timing diagram when a booster circuit of a DC power source is used as the supply voltage power source of this embodiment.
FIG. 3 is a timing diagram when a full-wave rectifier circuit of the 〇 power source is used as the supply voltage power source of this embodiment.

The directional control valve using the piezoelectric element of this embodiment is, for example, an air-operated double pilot type directional control valve, in which the valve body 1 and the driving parts 2a and 2b sandwiching the valve body 1 are coaxial. The power supply section 3 is connected as a voltage source for the drive sections 2a and 2b.

An input port 4 and discharge ports 5a, 5b connected to an M body pressure source (not shown) are provided on the lower side of the valve body 1, and output ports a, 5b are provided on the upper side of the valve body 1.
6b has been opened.

A flow path 7 is formed inside the valve body 1 along its axial direction, and valve seats 8a to 8d are disposed on the inner peripheral surface of the flow path 7 at predetermined intervals along the axial direction. It is set up.

A main shaft 9 is disposed in the flow path 7 so as to be freely displaceable along its axial direction, and main shaft valve bodies 10a to 10d, which are brought into contact with and separated from the valve seats 8a to 8d, respectively, are spaced from the main shaft 9 at predetermined intervals in the axial direction. It is formed by

Pistons 11a and 11b as actuating members of the main shaft 9 are provided on both end faces of the main shaft 9, fixed or non-fixed to the end face of the main shaft 9.
one working fluid chamber 12a.

12b, and a fluid chamber 12a for these operations.

It is accommodated within 12b so as to be freely displaceable along the axial direction.

Of these working fluid chambers 12a, 12b, the left working fluid chamber 12 a i! in FIG. Through hole 13a
The pilot fluid chamber 14a is communicated with the pilot fluid chamber 14a through the pilot fluid chamber 14a.

Further, the pilot fluid chamber 14a is communicated with the outside through a bleed hole 15a, and the bleed hole 15a is opened at a position where it is closed when fluid pressure flows into the pilot fluid chamber 14a.

Furthermore, a piezoelectric element 16a is provided in the pilot fluid chamber 14a, and this piezoelectric element 16a has a bimorph structure that is displaced on one side by the application of a pulse voltage, and is fixed at one end (the lower end in FIG. 1) and the other end is non-contact. It has a fixed cantilever structure.

A pilot valve body 17a is fixed to both sides of the non-fixed end of the piezoelectric element 16a, and the pilot valve body 17a is biased to the right in FIG. A spring 20a is provided.

Further, the pilot valve body 17a on one side of the piezoelectric element 16a (the right side in FIG. 1) is biased by a spring 20a.
Nozzle 1 of inflow path 18 that communicates with manual port 4 under normal conditions
9a is occluded.

On the other hand, the piezoelectric element 16a is driven by the power supply section 3, and the piezoelectric element 16a is bent to the left in FIG. 1 against the biasing force of the spring 20a.
The pilot valve body 17a on one side (the right side in the figure) opens the nozzle 19a, and the pilot valve body 17a on the other side (the left side in the figure) closes the bleed hole 15a.

The structure described above for the piston lla, the piezoelectric element 16a, the pilot valve body 17a, etc. also applies to the piston llb, the piezoelectric element 16b1, the pilot valve body 17b, etc., which are similarly provided on the right end side of the main shaft 9 as seen in FIG. Since they are similar, the explanation of the latter will be omitted by adding a suffix to the same numbers as the former.

Further, the power supply section 3 includes a switch 21a for driving a circuit,
The one-shot pulse circuit 22 includes a one-shot pulse circuit 21b, and a supply voltage E is applied to this one-shot pulse circuit 22.

Then, switch 2 of this one-shot pulse circuit 22
1a is turned on, a driving voltage as a pulse voltage is applied to the piezoelectric element 1 from this one-shot pulse circuit 22.
6a and when the switch 21b is turned on, a driving voltage as a pulse voltage is applied from the one-shot pulse circuit 22 to the piezoelectric element 16b.

Next, the operation of this embodiment will be explained by the one-shot pulse circuit 22.
A case will be described with reference to FIG. 2 in which a booster circuit of a DC power supply is used as the power supply voltage of the supply voltage E to the circuit.

First, when the state of the switch 21a connected to the one-shot pulse circuit 22 is turned on as shown in FIG. A voltage is applied from the one-shot pulse circuit 22 of the power supply section 3 to, for example, one piezoelectric element 16a (on the left side in FIG. 1).

At this time, the free end of the piezoelectric element 16a is connected to the spring 20a.
resists the urging force of , and is curved to the left in FIG. 1 for a period of one pulse width.

Thereby, the pilot valve body 17a on the right side of the piezoelectric element 16a opens the nozzle 19a for a time corresponding to the width of one pulse, as in the state shown in FIG. The piezoelectric element 16a on the left side of FIG. 1 is shown in a state in which a pulse voltage is applied.

Further, the nozzle 19a is opened for one pulse and then immediately closed.

Therefore, the fluid pressure flowing from the input port 4 flows through the inflow path 18, the nozzle 19a, and further the pilot fluid chamber 14a1.
One pulse of fluid flows into the working fluid chamber 12a through the through hole 13a.

As a result, the fluid pressure in the working fluid chamber 12a increases as shown in FIG. 2(C) after a slight delay due to the displacement of the piezoelectric element 16a, pushing the piston lla to the right of the working fluid chamber 12a. Therefore, the main shaft 9 moves to the right in FIG.

In this case, the bleed hole 15a is closed and leakage of fluid pressure can be prevented, so that the fluid pressure can be quickly increased.

Furthermore, the fluid pressure in the working fluid chamber 12a is controlled by the piezoelectric element 16.
At the same time as the application of the drive voltage to a ends, the bleed hole 1
Since fluid pressure corresponding to one pulse is released from 5a to the outside, it gradually decreases as shown in FIG. 2(C).

Furthermore, with a slight delay in the displacement of the piston lla and the main shaft 9 due to an increase in the fluid pressure in the working fluid chamber 12a, fluid pressure flows from the input port 4 to the output port a, and the fluid pressure in the output port a is The pressure increases as shown in FIG. 2(d), and reaches a saturated state at the supply fluid pressure of the manual port 4.

At this time, the fluid pressure from the output port 6b is discharged through the discharge port 5b, so the fluid pressure at the output port b decreases as shown in Figure 2.

Furthermore, after the displacement of the main shaft 9 has been confirmed and the switch has been reliably switched, for example, after a time difference T has elapsed since the switch 21a was turned off, the state of the switch 21b is changed to the state shown in FIG. 2(e).
When turned on as shown above, the piezoelectric element 16bi
, : A one-pulse driving voltage as shown in FIG. 2(f) is applied from the one-shot pulse circuit 22 by the step-up circuit of the DC power supply.

At this time, the free end of the piezoelectric element 16b is connected to the spring 20b.
resisting the urging force of the first pulse for a time corresponding to the width of l pulse.
Displaced to the right side in the figure, the pilot valve body 17b on the left side of the piezoelectric element 16b opens the nozzle 19b.

Further, the nozzle 19b is opened for one pulse and then immediately closed.

Therefore, the fluid pressure from the input port 4 flows through the inflow path 18, the nozzle 19b1, and the pilot fluid chamber 14b.

One pulse of fluid flows into the working fluid chamber 12b through the through hole 13b.

As a result, after a slight delay due to the displacement of the piezoelectric element 16b, the fluid pressure in the working fluid chamber 12b increases as shown in FIG. 1, the main shaft 9 also moves to the left in FIG.

In this case, the bleed hole 15b is closed and leakage of fluid pressure can be prevented, so that the fluid pressure can be quickly increased.

Furthermore, the fluid pressure in the working fluid chamber 12b is controlled by the piezoelectric element 16.
At the same time as the application of the drive voltage to b ends, the bleed hole 1
Since the fluid pressure corresponding to one pulse is released from 5b to the outside, it gradually decreases as shown in FIG. 2 ((a)).

Furthermore, since the input port 4 is communicated with the output port b, the fluid pressure of the output port b is adjusted to the same level as shown in FIG. The supply fluid pressure of the input port 4 reaches a saturated state.

At this time, since the output port a is communicated with the discharge port 5a, the fluid pressure of the output port 6a decreases as shown in FIG. 2(d).

As described above, according to the directional control valve of this embodiment, the bleed holes 15a and 15b are connected to the piezoelectric element 16 when fluid pressure flows in.
The hole is opened in a position where it can be closed by the pilot valve element 17a fixed to the left side of the piezoelectric element 17a and the pilot valve element 17b fixed to the right side of the piezoelectric element 16b, so that when the fluid pressure increases, the fluid pressure is increased. Since leakage can be prevented, the main shaft 9 can be displaced quickly.

Further, the piezoelectric element 16a is displaced by the switch 21a of the one-shot pulse circuit 22, and the switch 21b
By displacing the piezoelectric element 16b, the switches 21a and 21b can be switched after confirming the operation of the main shaft 9, so that the flow of fluid pressure can be reliably controlled.

As above, the invention made by the present inventor has been specifically explained based on examples, but it goes without saying that the present invention is not limited to the above-mentioned examples, and can be modified in various ways without departing from the gist thereof. Nor. - For example, in the directional control valve of this embodiment, as the power supply voltage of the supply voltage E to the one-shot pulse circuit 22,
Although the case where a booster circuit of a DCIE source is used has been described, the present invention is not limited to the above embodiment, and can also be applied to a case where a full-wave rectifier circuit of an AC power source is used, as shown in FIG. 3, for example. It is.

In this case, the driving voltage of the piezoelectric elements 16a, 16b is not a square wave as shown in FIG. 2(b), but is a full-wave rectified AC wave as shown in FIGS. In addition to the waveform, the working fluid chamber 12' as shown in Fig. 3 (C).
The rising waveforms of a and 12b when the fluid pressure increases are also the second waveforms.
Although different from the cases in Figures (C) and (g), the timing diagrams in Figures 3(a) to 3(a) are basically the same as those in Figure 2(a).
) to (company). Also, Figure 3(a)
The main shaft 9, pistons lla, llb, and piezoelectric elements 16a, 1 of the embodiment shown in FIG.
6b and a pilot valve body 17a.

The operations of 17b and the like are the same as those shown in FIGS.

Furthermore, in the directional control valve of this embodiment, the piezoelectric element 16
Pistons lla and llb were used as actuating members for the displacement of the main shaft 9 by a and 16b;
A diaphragm can also be used instead of la, llb.

〔Effect of the invention〕

A brief explanation of the effects obtained from typical inventions disclosed in this application is as follows.

[1] In a directional control valve equipped with an actuating member that is displaced by the fluid pressure in the actuating fluid chamber, and a main shaft in which a valve body that controls a flow path is formed by the displacement of the actuating member, the actuating fluid chamber is By providing a piezoelectric element that is displaced on one side by the application of a pulse voltage in the pilot fluid chamber that is communicated, the piezoelectric element is driven by the application of the pulse voltage, and voltage is not continuously applied to the piezoelectric element for a long time. Therefore, it is possible to prevent polarization deterioration due to polarization phenomenon,
Furthermore, since the piezoelectric element is only displaced on one side by the pulse width when a pulse voltage is applied, deformation due to creep phenomenon can be prevented.

(2) According to (1) above, leakage of fluid pressure is prevented by preventing deterioration of polarization and deformation, and operation stability and longevity are made possible.At the same time, the piezoelectric element Since it is sufficient to have an effective cross-sectional area sufficient to control the pressure, it is possible to reduce the load applied to the piezoelectric element.

(3) A piezoelectric element that is displaced on one side by application of a pulse voltage in a pilot fluid chamber that communicates with the operating fluid chamber 9, and a pilot valve body that is fixed to each main surface of the displacement end of this piezoelectric element, A fluid pressure inflow path and a fluid pressure bleed hole communicate with the pilot fluid chamber, and when the piezoelectric element is displaced, the fluid pressure inflow path is opened by one side of the pilot valve body, and the fluid pressure bleed hole communicates with the pilot valve body. By being closed by the other side of the pilot fluid chamber, the fluid pressure bleed hole is closed when fluid pressure flows in, and it is possible to prevent fluid pressure from leaking in the pilot fluid chamber when the fluid pressure increases, so that the displacement of the main shaft is reduced. It is possible to quickly control the flow of fluid pressure.

(4) In a double pilot type directional control valve, a first piezoelectric element that is displaced on one side by application of a pulse voltage within the first and second pilot fluid chambers that communicate with the first and second operating fluid chambers. and a second piezoelectric element, and a first switch and a second switch that apply a pulse voltage to the first and second piezoelectric elements, the first switch displacing the first piezoelectric element. , and by displacing the second piezoelectric element using the second switch and independently opening and closing the first fluid pressure inflow path and the second fluid pressure inflow path communicating with the first and second pilot fluid chambers. , the first and second switches can be switched after confirming the operation of the main shaft displaced via the first and second actuating members, so that the main shaft is reliably operated and the flow of fluid pressure is controlled. can be reliably controlled.

(5) Due to (1) to (4) above, the piezoelectric element is reduced in size by reducing the load on it, and at the same time, the directional control allows for quick and reliable switching of fluid pressure. A valve and a method for driving the same can be obtained.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of a directional control valve using a piezoelectric element, which is an embodiment of the present invention, and Fig. 2 is a timing line when a step-up circuit of a DC power supply is used as the supply voltage power source of this embodiment. 3 are timing diagrams when a full-wave rectifier circuit of an AC power source is used as the supply voltage power source of this embodiment. l... Valve body, 2a, 2b... Drive section, 3... Power supply section, 4... Input boat, 5a, 5b... Discharge Port, 5a, 5b...Output port, 7...Flow path, 8a-8d...Valve seat, 9...Main shaft, 103-10d...Main shaft valve body, 11a, llb...Piston (operating member), 12a, 1
2b...operating fluid chamber, 13a, 13b...through hole 14a, 14b...pilot fluid chamber, 15a, 1
5b...Bleed hole, 16a, 16b...Piezoelectric element, 17a, 17b...Pilot valve body, 18...
...Inflow path, 19a, 19b...Nozzle, 20a, 20b...Spring, 21a, 21b...Switch, 22...One-shot pulse circuit, E...
...Supply voltage, T...Time difference.

Claims (1)

[Claims] 1. An operating member that is displaced by fluid pressure in an operating fluid chamber;
A directional control valve comprising a main shaft in which a valve body for controlling a flow path is formed by displacement of the actuating member, the directional control valve having one side displaced by application of a pulse voltage in a pilot fluid chamber communicating with the actuating fluid chamber. It includes a piezoelectric element and a pilot valve body fixed to each main surface of the displacement end of the piezoelectric element, and a fluid pressure inflow path and a fluid pressure bleed hole are communicated with the pilot fluid chamber, and when the piezoelectric element is displaced, the fluid pressure inflow path is opened by one side of the pilot valve body;
A directional control valve using a piezoelectric element, wherein the fluid pressure bleed hole is closed by the other side of the pilot valve body. 2. A first actuating member and a second actuating member that are displaced by fluid pressure in the first and second actuating fluid chambers, and a valve body that controls a flow path by displacement of the first and second actuating members. A double pilot type directional control valve having a main shaft formed with A first piezoelectric element and a second piezoelectric element that are displaced on one side; a first switch and a second switch that apply a pulse voltage to the first and second piezoelectric elements; displacing the first piezoelectric element and displacing the second piezoelectric element by the second switch; and a first fluid pressure inflow path and a second 1. A method for driving a directional control valve using a piezoelectric element, characterized by independently opening and closing a fluid pressure inflow path.