JPH05327055A - Piezoelectric actuator - Google Patents

Abstract

PURPOSE:To protect the occurrence of the disconnection of a lead wire by the cause of turning of a piezoelectric element in a case. CONSTITUTION:Ring-like elastic supporting bodies 14 are inserted in between a cylindrical case 2 and laminated piezoelectric elements 3. By this, even if a movable piece 5, the piezoelectric elements 3, and the case 2 strike each other like multicar collision by the delay of the follow-up operation of the movable piece 5 caused by a returning spring 4 when the piezoelectric elements 3 contract, the piezoelectric elements 3 can be appropriately held by the elastic supporting bodies 14, thereby resulting in no turning of the piezoelectric elements.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an actuator using a laminated piezoelectric element (referred to as a piezoelectric actuator), and in particular, a voltage is applied to the piezoelectric element to cause it to expand and contract in the axial direction for precise fine positioning, stroke drive, and application. The present invention relates to an actuator that vibrates.

[0002]

2. Description of the Related Art FIG. 4 is a longitudinal sectional view of a conventional press working apparatus using the above piezoelectric actuator. In the case of the piezoelectric actuator 1, two laminated piezoelectric elements 3 are housed in a cylindrical case 2 in the case of the figure, and the displacement of the piezoelectric element 3 is transmitted via a movable piece 5 preloaded by a return spring 4. It has become. When a pulse voltage is repeatedly applied to the piezoelectric element 3 from the power source 6 through the lead wire 7, the piezoelectric element 3 expands and contracts to drive the movable piece 5 to vibrate, and the workpiece 9 held by the die 8 is punched out. ..

[0003]

In such a piezoelectric actuator 1, the movable piece 5 moves when the piezoelectric element 3 contracts.
The return operation of is not in time, and an internal collision occurs like a bead. This will be described below. When the voltage rises from the initial state of (A), the piezoelectric element 3 expands as shown in (B). Next, when the voltage falls, the piezoelectric element 3 contracts toward its center, but since the piezoelectric element 3 has a high responsiveness, the movable piece 5 cannot follow it even if the spring 4 is loaded. As shown in FIG.

After that, when the movable piece 5 driven by the spring 4 starts moving, the gap G is erased one after another as shown in (D) to (G), during which the operating piece 5, the piezoelectric element 3 and the piezoelectric element 3 The elements 3 collide with each other, and the piezoelectric element 3 and the case 2 collide with each other. Therefore, conventionally, a collision sound is generated when the piezoelectric element 3 contracts. The piezoelectric element 3 rotates in the case 1 and the lead wire 7 is broken during the accumulation of several millions to tens of millions of collisions. However, there is a problem that a residual vibration of the movable piece 5 is generated for a long time due to the reaction of the collision and the end surface of the piezoelectric element 3 is chipped due to the collision. Therefore, an object of the present invention is to provide a piezoelectric actuator in which the above-mentioned collision when the piezoelectric element contracts is mitigated to prevent breakage of the lead wire.

[0005]

In order to achieve the above object, the present invention has an annular elastic support interposed between a case and a piezoelectric element.

[0006]

A ring-shaped elastic support member made of rubber or the like is inserted between the case and the piezoelectric element to elastically connect the case and the piezoelectric element. As a result, the rotation of the piezoelectric element is suppressed, and the impact of collision that occurs between the movable piece and the piezoelectric element is mitigated. In order to sufficiently exert the shock absorbing effect of the elastic support, it is preferable to incorporate the elastic support closer to the movable piece side than the center of the piezoelectric element. Further, in order to damp the residual vibration of the movable piece in a short time, a damping body may be inserted between the movable piece and its guide.

[0007]

1 is a longitudinal sectional view of a piezoelectric actuator 1 showing an embodiment of the present invention. In this case, three piezoelectric elements 3 are housed in a cylindrical case 2 in order to increase the stroke, and the movable piece 5 is provided with a return spring 4 formed of a disc spring inserted between the movable piece 5 and the guide 10 to lead the piezoelectric element. Pressed to 3. An inclined piece 11 and a wedge 12 are provided between the bottom surface of the case 2 and the piezoelectric element 3, and the initial position of the movable piece 5 can be set by moving the wedge 12 in and out with an adjusting screw 13.

An annular elastic support 14 made of rubber is interposed between the case 2 and the piezoelectric element 3 at three axial positions. FIG. 2 is a perspective view of the elastic support 14, and FIG. 3 is a sectional view thereof. As shown in the figure, a groove 15 is formed on the outer periphery of the elastic support member 14 so that the elastic support member 14 can be slightly bent and deformed in the axial direction. Further, the inner peripheral surface 14a is provided with a slight bulge. The elastic support 14 is inserted with a holding force such that the piezoelectric element 3 does not rotate in the case 2 due to the above-mentioned collision, and the lead wire 7 of each piezoelectric element 3 passes through the hole 16 in the axial direction of the elastic support 14, It is drawn out to the outside along the inner wall surface of the case 2. In addition, the movable piece 5 and the guide 1
An annular damping body 17 is inserted between 0 and 0.

In such a structure, when a pulse voltage is applied through the lead wire 7 and the piezoelectric element 3 expands and contracts, the elastic support 14 also flexes in the axial direction accordingly. At that time, as described above, a collision like a collision occurs in the case 2, but since the piezoelectric element 3 is held by the elastic support body 14 with respect to the case 2, the piezoelectric element 3 does not rotate and the impact of the collision is elastic. It is relaxed by the support 14. Therefore, the lead wire 7 is not broken or the piezoelectric element 3 is not chipped. Further, since the movable piece 5 is in contact with the damping body 17, the generated residual vibration is quickly damped. When the piezoelectric element 3 and the case 2 have a rectangular cross section or other shapes, the inner and outer shapes of the elastic support body 14 are also adapted to them.

[0010]

According to the present invention, by inserting an annular elastic support between the case and the piezoelectric element, the piezoelectric element is held appropriately with respect to the case, and the shock is alleviated. There is no risk of breakage of the lead wire or damage of the element itself due to collision when the element contracts.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an embodiment of the present invention.

FIG. 2 is a perspective view of an elastic support body in FIG.

FIG. 3 is a cross-sectional view of the elastic support body of FIG.

FIG. 4 is a vertical sectional view of a conventional example.

5A and 5B are diagrams illustrating a state of a collision that occurs in the piezoelectric actuator of FIG.

[Explanation of symbols]

 1 Piezoelectric Actuator 2 Case 3 Piezoelectric Element 4 Return Spring 5 Moving Piece 6 Power Supply 7 Lead Wire 14 Elastic Support

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H05K 7/12 A 7301-4E

Claims (1)

[Claims] 1. A piezoelectric actuator in which a laminated piezoelectric element is slidably housed in a tubular case, wherein an annular elastic support is interposed between the case and the piezoelectric element. Actuator.