JPH03234981A - Valve using laminate type piezoelectric element - Google Patents

Abstract

PURPOSE:To operate valves securely and stably by providing side by side the movable ends of the first and the second laminate type piezoelectric elements combining the movable end to a displacement member, expanding and displacing them in the directions perpendicular to the displacement in the expansion/contraction direction of the both the laminate type piezoelectric elements, depending on the difference in displacement amounts of the both the elements. CONSTITUTION:The size of the first laminate type piezoelectric element 2 is made a and the size of the second laminate type piezoelectric element 3 is made b, when the driving voltage is not applied, and the sizes when the driving voltage is applied are made A1 and B1 respectively. And when the voltage is applied to the elements 2 and 3 alternatively, the size difference between a and A1, and the size difference between b and B1 are generated, the size difference are expanded by a lever 4, and they are shown as the movements and the positions of valves 9 and 10. In this case, when the displacement amounts of the elements 2 and 3 are changed by the residual strain properties of the piezoelectric elements themselves, the residual strains are accumulated with the relation of the passage of operation time, and the sizes A2 and B2 including the size errors are generated. However, the size errors DELTAA and DELTAB of the residual strains, which are A2-A1=DELTAA, and B2-B1=DELTAB, are offset each other, and the operations in the lateral direction of the valves 9 and 10 are not changed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a valve using a laminated piezoelectric element, and in particular, a valve using a laminated piezoelectric element, in which the amount of displacement due to residual strain generated in the piezoelectric element is offset, and reliable and stable operation is possible. This invention relates to a technique that is effective when applied to valves using laminated piezoelectric elements.

[Conventional technology]

A valve using a piezoelectric element, for example, a switching valve, is composed of a driving part equipped with a piezoelectric element, and a valve body part equipped with an actuating member operated by displacement of the piezoelectric element. The structure is such that the piezoelectric element is displaced by applying a driving voltage to the piezoelectric element, and the operating member is operated in conjunction with this displacement, thereby opening and closing the fluid pressure passage.

[Problem to be solved by the invention]

However, in the prior art as described above, there is a problem in that the amount of displacement changes over time due to residual strain characteristics of the piezoelectric element itself, and fluid pressure leakage eventually occurs. Therefore, in order to reliably open and close the flow path, an important factor is how to reduce the residual strain in the piezoelectric element, and various efforts have been made to this end. However, it is extremely difficult to eliminate such residual strain in piezoelectric elements.

Therefore, an object of the present invention is to provide a laminated piezoelectric element that uses two sets of laminated piezoelectric elements so that the amount of displacement due to residual strain of the piezoelectric elements can be offset each other, thereby preventing leakage of fluid pressure and enabling reliable and stable opening/closing operation. An object of the present invention is to provide a valve using a shaped piezoelectric element.

[Means to solve the problem]

A valve using a laminated piezoelectric element of the present invention includes a laminated piezoelectric element that is displaced by application of a driving voltage, and a displacement member that is displaced in conjunction with the laminated piezoelectric element, A valve whose fluid pressure flow path is opened and closed by a first valve.
and a second laminated piezoelectric element, the movable ends of the first and second laminated piezoelectric elements are arranged in parallel and coupled to the displacement member. and the displacement member is moved in a direction perpendicular to the displacement in the expansion/contraction direction of the first and second laminated piezoelectric elements due to the difference in displacement between the first and second laminated piezoelectric elements. It is expanded and displaced.

Further, the amount of displacement due to the residual strain of the first laminated piezoelectric element and the amount of displacement due to the residual strain of the second laminated piezoelectric element are the same as the expansion and contraction of the first and second laminated piezoelectric elements. The amounts of displacement in the directions cancel each other out, so that the displacement deviation of the displacement member is limited to the amount of displacement in the expansion/contraction direction.

[Effect]

According to the above-mentioned valve using a laminated piezoelectric element, it is provided with two laminated piezoelectric elements, a first laminated piezoelectric element and a second laminated piezoelectric element, and these first and second laminated piezoelectric elements By arranging the movable ends of the laminated piezoelectric elements in parallel and coupling them to the displacement member, the displacement member can be moved between the first and second laminated piezoelectric elements due to the difference in displacement between the first laminated piezoelectric element and the second laminated piezoelectric element. It is possible to expand and displace the laminated piezoelectric element in the direction perpendicular to the displacement in the expansion/contraction direction. Thereby, the amount of displacement of the first and second laminated piezoelectric elements can be expanded by the displacement member, and the fluid pressure flow path can be opened and closed by the displacement of the displacement member.

In this case, the amount of displacement due to the residual strain of the first laminated piezoelectric element and the amount of displacement due to the residual strain of the second laminated piezoelectric element are expressed as Since they can be canceled out as displacements in the expansion and contraction direction,
The displacement deviation of the displacement member can be limited to the amount of displacement in the expansion/contraction direction.

〔Example〕

FIG. 1 is a sectional view showing a valve using a laminated piezoelectric element according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing the opening and closing operation of the valve using a laminated piezoelectric element of this embodiment. .

First, the structure of a valve using the laminated piezoelectric element of this embodiment will be explained with reference to FIG.

- The valve using the laminated piezoelectric element of this embodiment is, for example, a switching valve that switches a fluid pressure flow path, and has a first laminated piezoelectric element 2 and A second laminated piezoelectric element 3 and a lever 4 that is a displacement member that is displaced in conjunction with the first and second laminated piezoelectric elements 2 and 3 are housed.

The main body 1 has a valve chamber 5 formed therein into which fluid pressure flows, and an input port through which the valve chamber 5 communicates with the outside.
A discharge port 7 and an output port 8 are provided on the outer peripheral surface of the main body 1. The input port and discharge boat 7 are provided with valve seats 5a and 7a that protrude toward the valve chamber 5 side.

First laminated piezoelectric element 2 and second laminated piezoelectric element 3
are provided in parallel to the valve chamber 5 of the main body 1, and have fixed ends 2a,
3a is fixed to the main body 1, and the movable ends 2b, 3b are telescopically connected to the lever 4. Lead wires (not shown) to which a driving voltage is applied are connected to the first and second laminated piezoelectric elements 2.3, and they have a structure that expands and contracts when the driving voltage is supplied from the outside. It has become.

The lever (displacement member) 4 has movable ends 2b and 3b of the first and second laminated piezoelectric elements 2 and 3 arranged in parallel and connected to a fixed end 4a thereof, and a manual port is connected to both sides of the movable end 4b. and valves 9 and 10 by which the discharge boat 7 is opened and closed are fixed. The lever 4 is moved perpendicularly to the direction of expansion and contraction of the first and second laminated piezoelectric elements 2 and 3 due to the difference in displacement between the first and second laminated piezoelectric elements 2 and 3. It has a structure in which it is expanded and displaced in accordance with the length of the lever 4 in the left-right direction in FIG.

Next, the operation of this embodiment will be explained.

First, when no driving voltage is applied to the first and second laminated piezoelectric elements 2.3, the first and second laminated piezoelectric elements 2.3 are in a contracted state as shown in FIG. is,
The movable end 4b of the lever 4 is stationary at a neutral position between the valve seat 6a of the manual port and the valve seat 7a of the discharge port 7.

Then, for example, when a driving voltage is applied only to the first laminated piezoelectric element 2, only the first laminated piezoelectric element 2 is in an extended state, and the lever 4 is moved to fix the first laminated piezoelectric element 2. The end 4a side is slightly displaced. Then, this minute displacement amount is expanded by the length of the lever 4, and the movable end 4b of the lever 4 is expanded and displaced in the right direction of the arrow in FIG.

Thereby, the valve 10 fixed to the movable end 4b of the lever 4
The valve seat 7a of the discharge port 7 is closed, and the manual port and the output port 8 are communicated via the valve chamber 5. In this state, when fluid pressure such as air pressure is supplied to the input port from a fluid pressure source (not shown), the supplied fluid pressure is output from the manual port through the valve chamber 5 and the output port 8 to the outside.

Next, when the driving voltage to the first laminated piezoelectric element 2 is cut off and, conversely, the driving voltage is applied only to the second laminated piezoelectric element 3, only the second laminated piezoelectric element 3 expands. In this state, the fixed end 4a side of the second laminated piezoelectric element 3 of the lever 4 is slightly displaced.

Then, this minute displacement amount is magnified by the length of the lever 4, and the movable end 4b of the lever 4 is expanded and displaced in the left direction of the arrow in FIG.

As a result, the valve seat 6a of the input port is closed by the valve 9 fixed to the movable end 4b of the lever 4, and the discharge port 7 and the output port 8 are communicated via the valve chamber 5. In this state, for example, when fluid pressure is discharged from an externally connected fluid pressure operating device (not shown) to the output port 8, the discharged fluid pressure is discharged from the output port 8 through the valve chamber 5 and from the discharge port 7 to the outside. It is discharged.

In addition, in the switching valve operated in this way, for example, when the driving voltage is not applied, the first laminated piezoelectric element 2
As shown in FIG. 2, A1. is the dimension of a1. When a voltage is applied alternately to the first and second laminated piezoelectric elements 2.3 as B+, a and A1
There is a dimensional difference between b and 31. This dimensional difference is then magnified by the lever 4 and appears as the movement and position of the valves 9 and 10.

However, due to the residual strain characteristics of the piezoelectric element itself, the first
When the amount of displacement of the second laminated piezoelectric element 2.3 changes, residual strain accumulates over time, and as shown in FIG. 2, dimensions A2 and B2 including dimensional errors becomes. However, in the switching valve of this embodiment, the dimensional differences ΔA and ΔB of the residual strain of A2A1 - ΔAS82 B+ - ΔB cancel each other out, and when they are equal, the positions of the valves 9 and 10 are simply moved in the direction of expansion and contraction. The movement in the left and right direction is the same as the initial state, with only a deviation of the dimension Δ.

Therefore, according to the switching valve of this embodiment, the two laminated piezoelectric elements, the first laminated piezoelectric element 2 and the second laminated piezoelectric element 3, which are displaced by the application of a driving voltage, and the a lever (displacement member) 4 that is coupled to the first and second laminated piezoelectric elements 2, 3 and is expanded and displaced in a direction perpendicular to the direction of expansion and contraction of the first and second laminated piezoelectric elements 2.3; By having a displacement error of residual strain of the first laminated piezoelectric element 2 that occurs due to changes over time due to use, and a displacement error of the second laminated piezoelectric element 2,
and the displacement error due to the residual strain of the laminated piezoelectric element 3 can be canceled out from each other. As a result, the displacement of the lever 4 can be reduced to only the amount of displacement in the expansion/contraction direction, so that the opening/closing operations of the input port and the discharge port 7, which are greatly affected by the displacement in the left-right direction, can be performed reliably.

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 switching valve of this embodiment, a case has been described in which the driving voltage is applied alternately to the first laminated piezoelectric element 2 and the second laminated piezoelectric element 3, but the present invention is limited to the above embodiment. However, the present invention is also applicable to a case where driving voltages of different voltage levels are applied to both the first and second laminated piezoelectric elements 2.3, for example.

In this case, by keeping the relative potential difference between the applied drive voltages constant, the first and second laminated piezoelectric elements 2
, 3 can be generated evenly, so that not only reliable operation but also stable operation is possible.

In the above explanation, the invention made by the present inventor was mainly applied to a switching valve used in fluid pressure operated equipment, which is the field of application of the invention, but the invention is not limited to this, and the present invention is not limited to this. It is also widely applicable to other valve devices equipped with piezoelectric elements and displacement members actuated by displacement thereof.

〔Effect of the invention〕

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

A valve comprising a laminated piezoelectric element that is displaced by application of a driving voltage and a displacement member that is displaced in conjunction with the laminated piezoelectric element, and in which a fluid pressure flow path is opened and closed by displacement of the displacement member. The first multilayer piezoelectric element includes two multilayer piezoelectric elements, a first multilayer piezoelectric element and a second multilayer piezoelectric element.
and a second one, in which the movable ends of the laminated piezoelectric elements are arranged in parallel and coupled to a displacement member, and the displacement member is moved to the second laminated piezoelectric element due to the difference in displacement between the first laminated piezoelectric element and the second laminated piezoelectric element. By expanding and displacing the first and second laminated piezoelectric elements in a direction perpendicular to the direction of expansion and contraction, the displacement amount of the first and second laminated piezoelectric elements is expanded and displaced by the displacement member, and the fluid pressure is increased. The flow path can be opened and closed by displacement of the displacement member.

In this case, the displacement amount due to the residual strain of the first laminated piezoelectric element and the displacement amount due to the residual strain of the second laminated piezoelectric element are Since the displacement amounts in the directions can be canceled out, the displacement deviation of the displacement member can be limited to the displacement amount in the expansion/contraction direction.

As a result, it is possible to reliably open and close the fluid pressure passage, which depends on the displacement in the direction perpendicular to the direction of expansion and contraction of the first and second laminated piezoelectric elements, thereby preventing leakage of fluid pressure. Moreover, it is possible to obtain a valve using a laminated piezoelectric element that is capable of stable opening and closing operations.

2

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a valve using a laminated piezoelectric element according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing the opening and closing operation of the valve using a laminated piezoelectric element of this embodiment. . 1... Main body, 2... First laminated piezoelectric element, 2a... Fixed end, 2b... Movable end, 3... Second laminated piezoelectric Element, 3a... fixed end, 3b... movable end, 4... lever (displacement member), 4a... fixed end, 4b... movable end, 5... ... Valve chamber, 6... Input port, 6a... Valve seat, 7... Discharge boat, 7a... Valve seat, 8 - Output port, 9゜6 br mouth Patent applicant Koganei Seisakusho Co., Ltd.

Claims (2)

[Claims] 1. A valve comprising a laminated piezoelectric element that is displaced by application of a driving voltage, and a displacement member that is displaced in conjunction with the laminated piezoelectric element, and a fluid pressure flow path is opened and closed by displacement of the displacement member. , comprising two laminated piezoelectric elements, a first laminated piezoelectric element and a second laminated piezoelectric element, and the movable ends of the first and second laminated piezoelectric elements are arranged in parallel to cause the displacement. The displacement member is coupled to a member, and the displacement member responds to the displacement in the expansion/contraction direction of the first and second laminated piezoelectric elements due to the difference in displacement between the first and second laminated piezoelectric elements. A valve using a laminated piezoelectric element, which is characterized by being expanded and displaced in a right angle direction. 2. The amount of displacement due to the residual strain of the first laminated piezoelectric element and the amount of displacement due to the residual strain of the second laminated piezoelectric element are equal to each other in the expansion and contraction direction of the first and second laminated piezoelectric elements. 2. A valve using a laminated piezoelectric element according to claim 1, wherein the displacement amounts cancel each other out, and the displacement deviation of the displacement member is limited to the displacement amount in the expansion/contraction direction.