JPH0897479A - Multilayer piezoelectric actuator - Google Patents

Abstract

PURPOSE: To provide a multilayer piezoelectric actuator in which the heat of an actuator element is cooled down quickly to reduce the temperature change of a multilayer piezoelectric device and with which a proper displacement can be obtained. CONSTITUTION: A cooling cap 11 which performs cooling and has legs 12 is provided between a multilayer piezoelectric actuator 1 and a case 10. The heat produced by the operation of the multilayer piezoelectric actuator 1 is quickly cooled down through the legs 12 and the cooling cap 11, so that the temperature change of the multilayer piezoelectric actuator 1 can be suppressed and the proper displacement of the multilayer piezoelectric actuator 1 can be obtained stably and smoothly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated piezoelectric actuator (element) which is rapidly cooled by operation to reduce a temperature change to be stable and to obtain an appropriate displacement amount.

[0002]

2. Description of the Related Art Conventional laminated actuators are characterized by high response, high generated force, and high positional accuracy as compared with electromagnetic actuators, and are being applied in various fields. For example, conventionally, there is an actuator in which a thin piezoelectric pellet polarized in the thickness direction and a plurality of electrode plates for applying a voltage to the piezoelectric body are alternately stacked and the outer periphery thereof is covered with an insulating material such as an adhesive or a tube. There is (Practical application No. 4-58340).

[0003]

However, when this actuator is driven at high speed by alternating current, heat is generated due to hysteresis or the like, and the internal temperature of the actuator rises, resulting in unstable operation and deterioration of durability. That is, since the electrode plate uses a metal material or the like having a high thermal conductivity, heat transfer in the radial direction is easy, but the outer periphery is covered with an insulator having a low thermal conductivity, so that heat dissipation is insufficient. The present invention has been made to solve the problems of the prior art, and is a laminated structure that is simple in structure and easy to handle because it efficiently guides the heat generated inside the actuator to the outside and allows the inside of the actuator to operate at a stable temperature at all times. An object is to provide a piezoelectric actuator. That is, the present invention is a laminated type in which a thin member that has a high thermal conductivity in the laminating direction and is thermally coupled to the laminated body is provided between the outside of the pellet and the inside of the insulator, and the cooling performance is remarkably improved. An object is to provide a piezoelectric actuator.

[0004]

The laminated piezoelectric actuator of the present invention solves the above-mentioned problems of the prior art.
An accommodating member having a hollow accommodating portion in the wall, a thin piezoelectric body polarized in the thickness direction, an electrode plate connected to a power source for applying an electric field to the piezoelectric body, and an accommodating member accommodated in the accommodating member. A piezoelectric actuator, in which a plurality of piezoelectric bodies and electrode plates are alternately laminated to form a laminated body, and an electric field is applied to the piezoelectric body to obtain a displacement amount, the thermal conductivity being high between the housing member and the laminated body. And a thin member extending in the stacking direction of the laminated body and thermally connected to the laminated body to control the cooling of the piezoelectric actuator.

In the present invention, heat is conducted in the length direction (laminating direction) to improve the cooling performance. In order to guide this heat in the length direction, a thin plate made of metal or a diamond thin film is used as the thin member having high thermal conductivity. Since diamond has a high insulating property and has a thermal conductivity as large as ~ 5 times that of copper, it is extremely advantageous for securing the insulating property between electrodes and for downsizing. Diamond can be used alone, but diamond / metal composite (exD
(ia / Mo foil, Dia / wax material), a diamond / ceramics composite, etc., and can improve the strength of the diamond film and the manufacturability and workability of the curved shape.

[0006]

According to the laminated piezoelectric actuator of the present invention having the above-described structure, the thin piezoelectric member for controlling the cooling is provided to form an effective heat dissipation path, so that the laminated piezoelectric actuator is actuated through the thin member. It is possible to dissipate the heat generated in (1) and to cool it efficiently. That is, in the present invention, most of the heat generated in the piezoelectric body is transmitted to the outer periphery through the electrode plate and is efficiently guided to the upper end or the lower end of the laminated body through the thin member arranged on the outer periphery of the piezoelectric body. Since at least one of the end faces of the laminate is in contact with the structure, the end faces have a practical effect of being able to be cooled very easily. Further, the laminated piezoelectric actuator of the present invention can accurately reduce the temperature change, can stably and smoothly obtain an appropriate amount of displacement of the laminated piezoelectric actuator, reduce the strength of the piezoelectric body due to high temperature, and have characteristics. It has excellent practical effects that can suppress deterioration.

An embodiment of the laminated piezoelectric actuator of the present invention will be described below with reference to the drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the laminated piezoelectric actuator of the present invention will be described below with reference to the drawings.

[0008]

First Embodiment A laminated piezoelectric actuator 1 according to the first embodiment shown in FIGS. 1 and 2 has an electrode plate 2a, a disk-shaped piezoelectric body 4 having electrodes 3 printed or applied on both sides thereof, an electrode plate 2b, and a piezoelectric element. It is formed by stacking tens to hundreds of sheets in the order of the body 4. The thickness of each of the electrode plates 2a and 2b is several tens μm to several hundreds μm.
m, the electrode 3 is several μm to several tens of μm, and the piezoelectric body 4 is several hundred μm. The diameter of the electrode 3 is the same as or slightly smaller than that of the piezoelectric body 4. Part of the electrode plates 2a, 2b protrudes outside the piezoelectric body 4 and is a protrusion 5 as a conductive and heat conducting member.
Is formed, and protrusions 5a and 5b are formed on the outer side thereof and are bent and formed in the stacking direction. Electrode plates 2a, 2b
The inner diameter is configured substantially the same as the diameter of the electrode 3.

The electrode plates 2a and 2b have the same shape,
When laminating, the electrodes are displaced from each other so that the electrode plates 2a and 2b are 180 ° (or 60 °) apart from each other in the first embodiment.
°) It is installed at a different position. Electrode plates 2a, 2b
Every other sheet is integrally joined by the protrusions 5a and 5b, and two lead wires 7 are drawn out to the outside from the joined electrode strips 6a and 6b, respectively. The connection is good. Ceramic plates 8a and 8b are provided at both ends of the laminated body 1b for ensuring insulation and equalizing stress. Although the actuator 1 is integrated by joining the protrusions 5a and 5b, it may be further joined by a resin or the like for reinforcement. However, even if they are joined with resin or the like, the portions of the electrode plates 2a, 2b that project outward from the piezoelectric body 4 are provided so as to project outward from the resin.

The laminated piezoelectric actuator 1 of the first embodiment is housed in a hollow cylindrical case 10 as a housing member. A thin member, which is made of a material having a large thermal conductivity and extends in the stacking direction of the actuator 1 and is thermally connected to the stack 1b, is provided between the actuator 1 and the case 10, and controls the cooling of the actuator 1. The cooling cap 11 is provided. The cooling cap 11 is covered by the ground side electrode, and a plurality of, in the first embodiment, three leg portions 12 are provided so as to project according to the shape of the electrode plate 2a. Each of the legs 12 is thermally coupled to the end surface of the laminated body 1b.

In the laminated piezoelectric actuator 1 of the first embodiment having the above structure, when a potential difference is applied to the electrode plates 2a and 2b by the power source, the piezoelectric body 4 is distorted due to this potential difference. Since this potential difference is alternating, the displacement of the actuator 1 has a hysteresis loop. This hysteresis causes the actuator 1 to generate heat. Moreover, the laminated piezoelectric actuator 1 according to the first embodiment is provided with the cooling cap 11 which is electrically insulative and controls the cooling of the piezoelectric actuator 1 between the cases 10, so that the electrode plates 2a and 2b and the protrusions 5 are provided. The transferred internal heat can be transferred to both ends of the actuator 1 through the legs 12 of the cooling cap 11, and can be easily cooled by a structure or a cooling medium provided separately. For this reason, the laminated piezoelectric actuator 1 of the first embodiment is capable of extremely reducing the temperature change, and exhibits the practically excellent operational effect of obtaining an appropriate displacement amount of the laminated piezoelectric actuator 1 stably and smoothly.

[0012]

[Other Embodiments] FIGS. 3 to 5 show the structures of laminated piezoelectric actuators of other embodiments. In the embodiment of FIG. 3, a plurality of strip-shaped thin plates 21 for cooling are arranged between the actuator A and the case 20 at appropriate intervals in the circumferential direction. The strip-shaped thin plate 21 is made of a material having a high thermal conductivity, extends in the stacking direction of the actuator A, and is thermally coupled to the stack 22. The embodiment shown in FIG. 3 having the above-described structure has substantially the same operational effects as the first embodiment.

In the embodiment shown in FIG. 4, a plurality of diamond thin films 31 are arranged between the actuator B and the case 30 at appropriate intervals in the circumferential direction. Since this diamond thin film 31 has a high insulating property, a thin plate is arranged on both electrodes and it is extended in the stacking direction of the actuator B. The embodiment shown in FIG. 4 having the above-described structure has substantially the same operational effects as the above-mentioned embodiments.

In the embodiment shown in FIG. 5, a strip-shaped diamond thin film 41 is wound between the actuator C and the case 40 regardless of the electrodes. The embodiment shown in FIG. 5 having the above-described structure has substantially the same operational effects as the above-mentioned embodiments.

[Brief description of drawings]

FIG. 1 is a perspective view showing a laminated piezoelectric actuator according to a first embodiment.

FIG. 2 is a development view of the laminated piezoelectric actuator according to the first embodiment.

FIG. 3 is a perspective view of a laminated piezoelectric actuator according to another embodiment.

FIG. 4 is a perspective view of a laminated piezoelectric actuator according to another embodiment.

FIG. 5 is a perspective view of a laminated piezoelectric actuator according to another embodiment.

[Explanation of symbols]

 1, A, B, C Multilayer piezoelectric actuator 2a, 2b Electrode plate 4 Piezoelectric body 7 Lead wire 8a Ceramic plate 9 Metal plate 10 Case 11 Cooling cap 12 Leg 21 Strip thin plate 31 Diamond thin film 41 Band diamond thin film

Claims (1)

[Claims] 1. A storage member having a hollow storage portion in a wall portion, a thin piezoelectric body polarized in a thickness direction, an electrode plate connected to a power source for applying an electric field to the piezoelectric body, A piezoelectric actuator for accommodating a plurality of piezoelectric bodies and electrode plates alternately stacked in a storage member to form a laminated body and applying an electric field to the piezoelectric body to obtain a displacement amount between the storage member and the laminated body. And a thin piezoelectric member which is made of a material having a large thermal conductivity and which extends in the stacking direction of the stacked body and is thermally connected to the stacked body to control the cooling of the piezoelectric actuator. Actuator.