JPS6326476A - Electrostriction element - Google Patents

Abstract

PURPOSE:To prevent the increase of leakage current and dielectric breakdown by covering an electrostriction element with a covering layer serving both as insulation and dampproofing. CONSTITUTION:An electrostriction element 1 has a plurality of laminated piezoelectric ceramic layers 2, metallic seats 3 which have been bonded on the upper and lower surfaces of said piezoelectric ceramic layers 2, and internal electrodes 4 between respective piezoelectric ceramic layers 2. The outer circumference of the whole of these is closely covered with a covering layer 5 which consists of a plurality of layers of an insulating layer 5a and a dampproofing layer 5b having been laminated on said insulating layer 5a. The insulating layer 5a is formed by coating insulating polymeric materials, and the dampproofing layer 5b consists of a metallic layer which has been formed so as to be laminated into a high polymer layer by means of spattering, vapor deposition, or the like.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an electrostrictive element such as a bimorph, unimorph, or laminated type, and more specifically to an electrostrictive element that takes insulation and moisture-proofing properties into consideration, and in particular, an electrostrictive element that takes into account insulation and moisture resistance. The present invention relates to an electrostrictive element that is effective for driving a valve body in a valve for equipment.

[Conventional technology]

Usually, an electrostrictive element generates strain by applying a relatively high DC voltage to the electrostrictive element. For this reason, for example, in a valve where the valve body is driven by the strain of an electrostrictive element,
It is necessary to electrically insulate the electrostrictive element from the valve body.

Therefore, considering this necessity, the insulating structure of the electrostrictive element may be one coated with a polymer paint or a polymer film adhered to the outer periphery.

2. Problems to be Solved by the Invention: However, electrostrictive elements whose outer peripheries are coated with polymeric paint or 7-strictive elements with polymeric films adhered to them are difficult to solve because such polymeric materials have hygroscopicity or moisture permeability. Therefore, moisture absorption or permeation of the polymer material may deteriorate the insulation properties between the internal electrodes of the electrostrictive element, increase leakage current, cause dielectric breakdown, or even reduce the strength of the electric field. The amount of displacement may decrease. For this reason, an electrostrictive element that not only has insulation properties but also moisture resistance is desired.

The present invention has been made in view of the above-mentioned problems, and its purpose is to provide an electrostrictive element with excellent insulation and moisture-proof properties.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention provides an electrostrictive element coated with a single coating or a plurality of coating layers having both insulation and moisture-proof properties.

[Function] Since the electrostrictive element according to the above-mentioned means is covered with a coating layer having both insulation and moisture-proofing properties, this coating 1
This makes it possible to obtain not only absolute resistance performance but also moisture-proof performance, which prevents deterioration of insulation properties due to moisture absorption or permeation of the electrostrictive element, increase of leakage current due to this deterioration, dielectric breakdown, and furthermore, the strength of the electric field. It is possible to prevent a decrease in the amount of displacement due to a decrease in .

[Example 1] FIG. 1 is a schematic cross-sectional view of an electrostrictive element that is an example of the present invention,
Figure 2 is a sectional view of a valve using the electrostrictive element shown in Figure 1.

The electrostrictive element 1 of this embodiment is a multilayer structure having a plurality of laminated piezoelectric ceramic layers 2, metal layers 3 bonded above and below the piezoelectric ceramic layers 2, and internal electrodes 4 between the piezoelectric ceramic layers 2. The entire outer periphery of the electrostrictive element is closely covered with a coating layer 5 consisting of a plurality of layers including an insulating layer 5a and a moisture-proof layer 5b laminated on the insulating layer 5a. There is. The former insulating layer 5a is made of a polymer layer formed by coating an insulating polymer material, and the latter moisture-proof layer 5b is formed by sputtering,
The metal stone is formed by laminating the polymer layer on the polymer layer by means such as vapor deposition or ion blating.

In such a structure, the former polymer layer provides insulation performance of the electrostrictive element 1, while the latter metal layer provides moisture-proof performance of the electrostrictive element 1. That is, although the polymer layer has excellent insulating properties, its moisture-proofing properties are not necessarily sufficient, so the moisture-proofing properties are ensured by the metal layer in which the moisture-proofing properties are soaked. On the other hand, although the metal layer has poor moisture-proofing properties, it does not necessarily have sufficient insulation, so insulation is ensured by a polymer layer that has excellent insulation.

In this way, the polymer layer with excellent insulating properties and the metal layer with excellent moisture-proofing properties complement each other, thereby ensuring both the insulating and moisture-proofing properties of the electrostrictive element 1. .

In addition, the electrostrictive element 1 is connected to the piezoelectric ceramic layer 2 for JN.
It has a book lead wire 6.

Next, regarding the valve 7 using the electrostrictive element 1 of this embodiment, a second
This will be explained with reference to the figures.

Inside the block-shaped main body 8, a sealed valve body chamber A is formed. This valve body chamber A has an artificial flow path (IN) 9 and an exhaust flow path (EXH) that penetrate the wall surface of the main body 8.
10 are opened at opposing positions, and a valve seat 11 and a valve seat 12 are provided protruding from the openings inside the valve body chamber A of the artificial flow path 9 and the exhaust flow path 10, respectively.

Further, an outlet flow path (OUT) 13 is formed near the exhaust flow path 10 by penetrating the wall surface of the main body 8 .

Inside the valve body chamber A, there is a U-shaped frame member 14a, one end of which is deformably fixed integrally with the frame member 14a, and the other end of which is connected to the valves of the inlet flow path 9 and the exhaust flow path 10. Seat 11 and valve seat 12
A displacement amplifying mechanism 14 consisting of an arm 14b extending between the frame member 14a and the main body 8 is provided, and the displacement amplifying mechanism 14 is fixed to the main body 8 by locking a part of the frame member 14a to the main body 8. ing.

The electrostrictive element 1 of this embodiment is provided in its displacement magnification mechanism 14. That is, one end of the electrostrictive element 1) is connected to the frame H.
14a, the other end is locked to arm 14b,
It is provided substantially parallel to the opposing direction of the valve seat 11 and the valve seat 12.

Then, a DC voltage of a predetermined polarity is applied from the outside through the lead wire 6, and a relatively small expansion/contraction displacement of the electrostrictive element 1 generated at that time causes the arm 14 to move due to the lever principle.
b, and the end of the arm 14b is connected to the valve seat 11.
The structure is such that when the valve moves back and forth between the valve seat 12 and the valve seat 12, the displacement is magnified to a large extent and output.

A valve seat 11 and a valve seat 12 are provided at the end of the arm 14b.
The valve body 15 and the valve body 16 are respectively locked in positions facing each other, and the valve body 15t or the valve body 16 is brought into close contact with the valve seat 11 or the valve seat 12, and is separated from the valve seat 11 or the valve seat 12 by driving the arm 14b. It is composed of

That is, when the electrostrictive element 1 is extended, the arm 14
The end of b is displaced in the direction approaching the valve seat 11, and the valve body 1
5 is brought into close contact with the valve seat 11, and the inlet flow path 9 is closed. Conversely, when the electrostrictive element l is retracted, the end of the arm 14b is displaced in the direction approaching the valve seat 12, and the valve (main 16 is brought into close contact with the valve seat 12, so that the exhaust flow path 10 is closed.

A buffer mechanism 17 is provided between the valve body 5 and the arm 14b.

This buffer mechanism 17 includes a stator 17a fixed to the side of the arm 14b, and a movable lever guided by the stator 17a and movably supported by the arm 14b via a spring 17b. 17c etc.

Such a buffer mechanism 17 allows the valve body 15 to reduce the population flow by ¥8.
The shock caused when the arm 14b is brought into close contact with the valve seat 11 of the arm 14b is absorbed, and the inclination of the arm 14b with respect to the valve seat 11/! The structure is such that the valve body 15 is reliably brought into close contact with the valve seat 11 without being influenced by the valve seat 11.

Similarly to the above, a valve ([tl18] having the same structure as the buffer mechanism 17 is provided between the valve body 16 and the arm 14b.

Further, the main body 8 and the arm 14b around the valve seat 11
A supporting spring configured to urge the end of the arm 14b in a direction approaching the valve seat 12, that is, to assist the displacement of the arm 14b due to contraction of the electrostrictive element 1. 19 are provided.

Next, the operation of this valve 7 will be explained.

First, when a direct current voltage of a predetermined polarity is applied to the electrostrictive element 1 via the lead wire 6 and a relatively small displacement is applied to the electrostrictive element 1 in the direction of extension, the arm 14b is moved by the lever principle. A relatively large displacement is generated at the end in the direction of bringing the valve body 15 closer to the valve l111. Then, the arm 14b approaches the valve seat 11 against the biasing force of the assisting spring 19, and the valve body 15 is brought into close contact with the valve seat 11, and the inlet flow path 9 is closed. Compressed air or the like is prevented from flowing into the valve body chamber A.

Conversely, when the polarity of the DC voltage applied to the electrostrictive element 1 is reversed and a relatively small displacement is applied to the electrostrictive element 1 in the direction of its contraction, the arm 1 of the displacement magnifying film t11II14
4b, the valve body 16 is attached to the valve seat 1 by the lever principle.
A relatively large displacement is generated in the direction of approaching 2.

Then, the valve body 15 is detached from the valve seat 11 and the artificial flow path 9
is opened, and the arm 14b and the supporting spring 1
Due to the biasing force 9, the valve body 16 is brought into close contact with the valve seat 2, and the exhaust flow path 10 is closed. As a result, compressed air flowing into the valve body chamber A from the artificial flow path 9 is supplied to a predetermined fluid pressure device (not shown) through the outlet flow path 13, and a predetermined work is performed.

Furthermore, when the polarity of the DC voltage applied to the electrostrictive element l is reversed to give the electrostrictive element l a displacement in the direction of its extension, the arm 14b is again relatively largely displaced in the direction approaching the artificial flow channel 9. be done. Then, the valve body 15 is brought into close contact with the valve seat 2, and the inlet flow path 9 is closed, and the valve f-116 is closed.
is removed from the valve seat 12 of the exhaust flow path 10 and the exhaust flow path IO
is opened, and the residual pressure inside the valve body chamber A, the outlet flow path 13, etc. is quickly discharged to the outside through the exhaust flow path IO.

[Embodiment 2] FIG. 3 is a schematic cross-sectional view of an electrostrictive element which is an embodiment of the pond of the present invention.

The electrostrictive element 1 of Example 2 is a laminated electrostrictive element like that of Example 1, and the structure other than the covering layer 5 is the same as that of Example 1. Therefore, the same reference numerals as those used in FIG. 1 are used in FIG. 3 for parts similar to the structure of the first embodiment, and the explanation thereof will be omitted.

The entire outer periphery of the electrostrictive element 1 is tightly covered with a single coating layer 5 having both insulation and moisture-proof properties.

This single coating layer 5 is made of silicon oxide (510
It consists of an insulating oxide layer, a compound layer thereof, or a glass layer such as 2). Here, the former oxide layer or its compound layer can be formed by means such as vapor deposition, ion blasting, sputtering, and vapor phase growth.

In particular, when forming a silicon oxide (SiO□) layer, a piezoelectric element with an uncoated jaw is heated, and monosilane (SiH4) and phosphine (
For example, it may be formed by reacting PH3) with oxygen. Further, as a means for forming the latter glass layer, a means for firing a glass material can be mentioned.

Incidentally, the electrostrictive element of the second embodiment can be used for the valve 7 described in the first embodiment, and the like.

[Example 3] Fig. 4 is a schematic sectional view of an electrostrictive element which is still another embodiment of the present invention, and Fig. 5 is a sectional view of a valve using the electrostrictive element shown in Fig. 4. .

The electrostrictive element 1 of Example 3 includes a metal plate 20, piezoelectric ceramic layers 2.2 attached to both sides of the metal plate 20,
It is a bimorph electrostrictive element having an electrode 21 provided on the surface of the metal plate 20 and electrodes 22 and 22 provided on the respective surfaces of the voltage ceramic layers 2, 2. The outer periphery, except for the tips of the electrodes 21, 22, and 22 to which the lead wires 6 are soldered, consists of a plurality of layers including an insulating layer 5a and a moisture-proof layer 5b laminated on this insulating layer 5a; It is tightly covered with a coating layer 5.

The structures of the insulating layer 5a and the moisture-proof layer 5b are the same as those in Example 1, so their explanation will be omitted. 7 will be explained with reference to FIG.

A valve body chamber A is formed inside the main body 8 of the valve 7 . In this valve body chamber A, an artificial passage (IN) 9 and an exhaust passage <EXH) 10 are provided facing each other through the wall surface of the main body 8. The internal openings to the valve body chambers each include a valve seat 11.
And a valve seat 12 is provided protrudingly.

Further, near the inlet flow path 9, an outlet flow path (OUT) 13 is formed passing through the wall surface of the main body 8.

The electrostrictive element 1 of this embodiment extends inside the valve body chamber A from above to below. That is, the upper end of the electrostrictive element 1 is integrally molded with a polymer material 8a above the valve body chamber, and the lower end is located between the valve seats 11 and 12. Further, the lead wire 6 of the electrostrictive element 1 is
It is molded by a and led out to the outside via a resistor 6a which is also molded. At the lower end of the electrostrictive element 1, a valve element 15 and a valve element 16 are provided at positions facing the right side of the valve seat 11 and the valve seat 12, respectively.
The valve seat 11 or the valve seat 12 is brought into close contact with the valve seat 11 or the valve seat 12 and removed from the valve seat 12.

That is, gold is supplied from a predetermined DC power source to the electrode 21 of the plate 20.
and a respective electrode 22.22 of the piezoceramic layer 2.2.
By applying a DC voltage of a desired polarity between , the electrostrictive element 1 bends with its upper end as a fulcrum toward the - valve seat side, for example, the valve seat 11 side of the artificial flow path 9, When the valve body 15 is in close contact with its valve seat 11 and a DC voltage of opposite polarity to that in the above case is applied, the electrostrictive element l uses its upper end as a fulcrum and moves toward the other valve seat side, that is, in this case, the exhaust gas. The valve body 15 is bent toward the valve seat 12 of the flow path 10 so that the valve body 15 is separated from the valve seat 11 of the artificial flow path 9, and the valve body 16 on the other side is in close contact with the valve seat 12 of the exhaust flow path 10. Next, the function of this valve 7 will be explained.

First, when a DC voltage of a predetermined polarity is applied to the electrostrictive element 1 via the lead wire 6, the electrostrictive element 1 moves toward the negative valve seat side, for example, to the left as shown in FIG. The valve body 15 on the same side is curved to the side and comes into close contact with the valve seat 11 on the same side.

This close contact of the valve body 15 with the valve seat 11 closes the artificial flow path 9, and prevents compressed air or the like acting on the artificial flow path 9 from flowing into the inside of the valve body chamber A.

On the other hand, when the polarity of the DC voltage applied to the electrostrictive element 1 is reversed, the electrostrictive element 1 turns to the other valve seat side, that is, to the right side in FIG. 5 in this case, using its upper end as a fulcrum. The valve body 15 on the left side is removed from the valve seat 11 on the same side, and the valve body 16 on the right side is removed.
is in close contact with the valve seat 12 on the same side. The separation of the left valve body 15 from the valve seat 11 on the same side opens the artificial flow path 9, allowing compressed air etc. to flow into the valve body chamber, and also causes the valve body 16 on the right side to separate from the valve seat 11 on the same side. The exhaust flow path 10 is closed by the close contact with the seat 12. As a result, compressed air flowing into the valve body chamber from the artificial flow path 9 is supplied to a predetermined fluid pressure device (not shown) through the outlet flow path 13, and a predetermined work is performed.

Furthermore, when the strength of the DC voltage applied to the electrostrictive element 1 is reversed, the electrostrictive element 1 curves to the left in FIG. 5 with its upper end as a fulcrum. Then, the valve body 15 on the left side comes into close contact with the valve seat 11 on the same side and the artificial flow path 9 is closed, and the valve body 16 on the right side separates from the valve seat 12 of the exhaust flow path 10 and the exhaust flow path 10 is closed. is opened, and the internal and outlet flow path 13 to the valve body chamber is opened.
The residual pressure is quickly discharged to the outside through the exhaust flow path 10.

[Embodiment 4] FIG. 6 is a schematic cross-sectional view of an electrostrictive element which is still another embodiment of the present invention.

The electrostrictive element 1 of Example 4 is a bimorph type electrostrictive element like that of Example 3, and the structure other than the covering layer 5 is the same as that of Example 3. therefore,
For parts similar to the structure of the third embodiment, the same reference numerals as those used in FIG. 4 are used in FIG. 6, and the explanation thereof will be omitted.

The entire outer periphery of the electrostrictive element 1 is tightly covered with a single coating layer 5 having both insulation and moisture-proof properties.

This single covering layer 5 is made of silicon oxide (S 1
It consists of an insulating oxide layer such as 02), a compound layer thereof, or a glass layer. Here, the former oxide layer or its compound layer can be formed by means such as vapor deposition, ion blasting, sputtering, and vapor phase growth. In particular, when forming silicon oxide (5102), it is formed by heating an uncovered piezoelectric element and reacting monolan (SiHl), phosphine (PH3>, and oxygen) on the heated piezoelectric element. In addition, as a means for forming the latter glass layer, a method for firing a glass material, etc. can be mentioned.The electrostrictive element 1 of Example 4 is 3
It is used in the valve 7 described in the embodiment.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. Nor.

For example, in the above-described embodiments, a laminated type or a bimorph type electrostrictive element is shown, but it may be a unimorph type, a bimorph type multiplexed type, or any other type.

Moreover, as the coating layer, materials other than those mentioned above can be used as long as they have both insulation and moisture-proof properties.

〔Effect of the invention〕

(1) 1 Since the present invention is an electrostrictive element covered with a coating layer having both insulation and moisture-proofing properties, the coating layer can provide both outstanding performance and moisture-proofing performance. It is possible to prevent deterioration of insulating properties due to moisture absorption or permeation of the electrostrictive element, an increase in leakage current and dielectric breakdown due to this deterioration, and furthermore, a decrease in displacement due to a decrease in electric field strength.

(2) If the electrostrictive element of the present invention is used to drive a valve body in a box, the performance of the valve can be improved as a result of the above (1).

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of an electrostrictive element which is an embodiment of the present invention;
FIG. 2 is a sectional view of a valve using the electrostrictive element shown in FIG. 1, FIG. 3 is a schematic sectional view of an electrostrictive element according to another embodiment of the present invention, and FIG. FIG. 5 is a schematic sectional view of an electrostrictive element according to another embodiment, FIG. 5 is a sectional view of a valve using the electrostrictive element shown in FIG. 4, and FIG. 6 is a schematic sectional view of another embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of an electrostrictive element. DESCRIPTION OF SYMBOLS 1... Electrostrictive element, 2... Piezoelectric ceramic layer, 3... Gold Tomiza, 4... Internal electrode, 5... Covering layer, 5a... Insulating layer, 5b... Moisture proofing 1. 6...Lead wire, 6a...Resistor, 7...Soup, 8...Main body, 8a...Polymer material, 9... ...Inlet flow path (IN), 10...Exhaust flow path (EXH), 11.12...
・Valve seat, 13... Outlet flow path (OUT), 14...
・Displacement magnifying mechanism, 14a...Frame material, 14b...Arm, 15.16...Valve body, 17.18...Buffer mechanism, 17a...Stator, 17b ... Spring, 17c ... Mover, 19 ... Helping spring, 20 ... Metal plate, 21, 22 ... Electrode, A ...・Valve body chamber.

Claims (8)

[Claims] (1) An electrostrictive element coated with a coating layer having both insulation and moisture-proof properties. (2) The electrostrictive element according to claim 1, wherein the coating layer is formed of a plurality of layers including an insulating layer and a moisture-proof layer. (3) The electrostrictive element according to claim 2, wherein the insulating layer is a polymer layer. (4) The electrostrictive element according to claim 2, wherein the moisture-proof layer is a metal layer. (5) The electrostrictive element according to claim 1, wherein the covering layer is formed from a single layer. (6) The electrostrictive element according to claim 5, wherein the covering layer is a silicon oxide layer. (7) The electrostrictive element according to claim 5, wherein the coating layer is a glass layer. (8) The electrostrictive element according to claim 1, which is an electrostrictive element for driving a valve body.