JPH05129674A - Piezoelectric actuator - Google Patents

Abstract

PURPOSE:To prevent a metal case and a metal member from being damaged or dented by providing a shock absorbing material at a part, or around the entire peripheral surface, of a metal member or a metal case which becomes a container so that all of the external shock which a piezoelectric actuator experiences can be absorbed by the shock absorbing material. CONSTITUTION:Lead wires 4a and 4b are connected across an electrostriction- effect element 1, in which a plurality of electrostriction materials and internal electrodes are alternately superimposed one over the other. A metal member 3, to which hermetic seal terminals 2a and 2b are fixed, and a metal member 6 are adhered to both ends of the electrostriction-effect element 1 by means of an epoxy adhesive. A metal case 5 such as a bellows is seal-connected to the metal members 3 and 6 by welding, so that the metal case is hermetically sealed. A silicon resin 7 which acts as a shock absorbing material to absorb an external shock is applied over the surface of the metal case 5 which becomes a container. Accordingly, it becomes possible to the metal case from dents, by means of the shock absorbing material, which may occur when the piezoelectric actuator falls down, or is dropped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric actuator using the electrostrictive effect, and more particularly to a structure of a piezoelectric actuator exterior using a metal case.

[0002]

2. Description of the Related Art A piezoelectric lye chute using an electrostrictive effect element that converts electric energy into mechanical energy is
Currently used in industrial fields such as mass flow controllers, XY table drives, and injection molding machines.

FIG. 5 is a vertical sectional view of a conventional piezoelectric actuator encased in a metal case. Conventionally, in this piezoelectric actuator, a metal member 3 including a hermetically sealed terminal 2 and a metal member 6 are alternately laminated with a plurality of electrostrictive materials and internal electrode conductors (for example, as in Japanese Patent Application No. 63-149158). The electrostrictive effect element 1 is composed of a bellows-shaped metal case 5 that is fixed to both ends of the electrostrictive effect element 1 with an adhesive such as an epoxy resin, and is seal-bonded to the metal members 3 and 6 by welding or the like.

[0004]

In the above-mentioned piezoelectric actuator, the electrostrictive effect element is sealed in the metal case 5 in order to improve the humidity resistance and the environment resistance of the electrostrictive effect element 1. The elastic metal bellows is used to transmit the electrostrictive effect element 1 to the outside without reducing the displacement amount of the electrostrictive effect element 1. Even though it is a metal bellows, it has a thickness of about 0.15 mm, and dents are made on the bellows part by a slight impact such as falling or falling, and the amount of displacement decreases due to the nicks, and stress during expansion and contraction However, there was a defect that the airtightness of the case was impaired due to the concentration of scratches on the dents.

[0005]

In the piezoelectric actuator of the present invention, a cushioning member such as silicon rubber is provided on a part or the entire circumferential surface of a metal member or a metal case which becomes a container.

[0006]

According to the above construction, since the shock absorbing member is provided on the metal case or the metal member, all external shocks applied to the piezoelectric actuator are absorbed, and the metal case and the metal member are scratched or dented. Can be prevented.

[0007]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a vertical sectional view of a piezoelectric actuator showing a first embodiment of the present invention.

In this piezoelectric actuator, lead wires 4a and 4b are connected to both ends of an electrostrictive effect element 1 formed by alternately laminating a plurality of electrostrictive materials and internal electrodes, and hermetically sealed terminals 2a and 2b are attached. The metal member 3 and the metal member 6 are fixed to both ends of the electrostrictive effect element 1 with an epoxy adhesive, and a metal case 5 such as a bellows having a stretch function is sealed to the metal members 3 and 6 by welding or the like. Combined and hermetically sealed.

On the surface of the metal case 5 serving as a container, as an example of a cushioning member for absorbing an external impact,
Silicon resin 7 is applied. Next, a method for manufacturing the piezoelectric actuator of this embodiment will be described. A multi-component solid solution ceramic powder having a perovskite crystal structure is mixed with an organic binder to form a green seal having a thickness of about 100 μm, a paste-like silver internal electrode conductor is applied on the green seal, dried, and then laminated into dozens of layers and baked. First, a laminated body is prepared. After alternately laminating alternate layers of glass insulating films on the end portions of the silver inner electrode conductors exposed on the pair of opposed side faces of this laminate, further external electrode conductors are formed on the side faces and the silver inner electrode conductors and the outer side. The electrostrictive effect element 1 in which the electrode conductors are alternately connected to every other layer is obtained. And lead wire 4
The a and 4b are soldered to the external electrode conductors and fixed with an adhesive such as an epoxy resin so that the electrostrictive effect element 1 is erected in the center of the inner surface of the metal member 3. Next, the lead wires 4a and 4b connected to the electrostrictive effect element 1 are connected to the hermetically sealed terminal 2
Solder with the inner ends of a and 2b.

Next, one in which one opening 5b of the metal case 5 and the metal member 6 are sealed and joined in advance by welding or the like is prepared. Next, the other end face portion 1b of the electrostrictive effect element 1 to which the metal member 3 is fixed is inserted from the opening 5a of the metal case 5 so that the electrostrictive effect element 1 is planted in the center of the metal member 6. Secure with an adhesive such as epoxy resin. Next, the metal member 3 and the opening 5a of the metal case 5 are sealed and joined together by welding or the like, and then the surface of the metal case to be the container is coated with the silicone resin 7 to form the piezoelectric actuator.

[0011]

Second Embodiment FIG. 2 is a vertical sectional view of a piezoelectric actuator showing a second embodiment of the present invention. This embodiment is the same as the first
Since it is the same as the first embodiment except that the shrinkable tube 8 is used as the cushioning member instead of the silicone resin 7 of the first embodiment, the same parts are designated by the same reference numerals and their description is omitted. Omit it.

In this embodiment, the use of the shrinkable tube 8 has an advantage that a certain shape and size can be easily obtained and the number of working steps can be reduced as compared with the first embodiment.

[0013]

[Third Embodiment] FIG. 3 is a longitudinal sectional view of a piezoelectric actuator according to a third embodiment of the present invention. This embodiment is the same as the first
The second embodiment is different from the first embodiment except that a plurality of ring-shaped silicon rubbers 9 are attached as buffer members to a part of the metal case instead of applying the silicon resin 7 on the entire surface of the metal case. Since it is similar to the example, the same parts are designated by the same reference numerals and the description thereof will be omitted. In this embodiment, by providing the convex portion of the silicon rubber 9 on the surface of the metal case 5, not only can the dent be prevented from being formed on the metal case as in the case of the first embodiment, but the silicon resin as in the first embodiment can be prevented. Since it is not necessary to coat the entire surface of the metal case, there is an advantage that the material and the work man-hour can be reduced.

[0014]

[Fourth Embodiment] FIG. 4 is a longitudinal sectional view of a piezoelectric actuator according to a fourth embodiment of the present invention. This embodiment corresponds to the third
Is different from the above embodiment in that cap-shaped silicone rubber 10a <10 is provided as a cushioning member on the metal members 3 and 6 at both ends.
The third embodiment is similar to the third embodiment except that it is crowned with b. Therefore, the same parts are designated by the same reference numerals and the description thereof will be omitted.

In this embodiment, in addition to preventing dents on the metal case portion, the roughness of the irregularities on the surface of the metal member can be mitigated to improve the workability of mounting the piezoelectric actuator.

[0016]

As described above, according to the present invention, by providing the metal case or the metal member with the cushioning member, it is possible to prevent the metal case from being dented due to a shock such as a fall or a drop due to a mishandling of the piezoelectric actuator. There is.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a piezoelectric actuator showing a first embodiment of the present invention.

FIG. 2 is a vertical sectional view of a piezoelectric actuator showing a second embodiment of the present invention.

FIG. 3 is a vertical sectional view of a piezoelectric actuator showing a third embodiment of the present invention.

FIG. 4 is a vertical sectional view of a piezoelectric actuator showing a fourth embodiment of the present invention.

FIG. 5 is a vertical cross-sectional view of a conventional piezoelectric lye chewer with a metal case. 1 Electrostrictive effect element 1a, 1b End surface 2a, 2b Glass terminal 3,6 Metal member (container) 4a, 4b Lead wire 5 Metal case (container) 5a 5b Opening 7 Cushioning member (silicone resin) 8 Cushioning member (shrinkable tube) 9a 9b Cushioning member (silicon ring) 10a, 10b Cushioning member (silicone cap)

Claims (2)

[Claims] 1. A piezoelectric actuator in which an electrostrictive effect element in which a plurality of electrostrictive materials and internal electrode conductors are alternately laminated is hermetically sealed by a metal case and a metal member to be a container, and a container surface including at least the metal case. A piezoelectric actuator, characterized in that a buffer member is provided in the. 2. The piezoelectric actuator according to claim 1, wherein the buffer member has a cap shape or a ring shape whose outer diameter is larger than the outer diameter of the container.