JPS6289370A - Piezoelectric bimorph device - Google Patents

Abstract

PURPOSE:To enable driving conditions of a piezoelectric bimorph element to be adjusted with simple operations, by mounting a permanent magnet movably along the profile of the piezoelectric bimorph element as defined with the piezoelectric bimorph element is deformed. CONSTITUTION:A piezoelectric bimorph element 1 is fixed with its end fixedly interposed between an end edge of a case body 91 and an end of a cover 92. Two contact pieces 10a and 10b are inserted into the other end wall of the case body 91, and the piezoelectric bimorph element 1 is arranged such that the free end thereof comes into or out of contact with these contact pieces 10a and 10b. A slot 91a and a groove 91b are formed according to the profile of the piezoelectric bimorph element 1 as defined when it is deformed. A magnet 8 magnetized in the direction orthogonal to the longitudinal axis is mounted. The magnet 8 has a slidable guide shaft 81 at one end and a guide shaft 82 serving also as a lug at the other end, and is slidable along the slot 91a and the groove 91b. Accordingly, the position (x) of the magnet 8 can be adjusted easily.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a piezoelectric bimorph device, and more particularly to a piezoelectric actuator that uses, for example, bending deformation of a piezoelectric bimorph element as a drive source for minute movements of various devices.

[Conventional technology]

When a piezoelectric actuator is operated by a constant input voltage, the relationship between deformation and force is such that when deformation is O, the force is maximum, and when deformation is maximum, the force in the deformation direction is O. Therefore, when configuring a piezoelectric relay or the like in which the operation of the free end of a piezoelectric bimorph element is used directly to open and close the contacts of the relay, the force that closes the contacts is extremely weak and impractical. Therefore.

Usually, a method was used in which the snap mechanism was driven by the slight deformation of a portion where the force was large and the deformation was small, or a method was used in which the weak force was reinforced by the attractive force of a permanent magnet at the time of maximum deformation. The operation of the latter configuration 1 will be explained with reference to FIG.

A ferromagnetic material 2 such as iron is placed near the tip of the piezoelectric bimorph element 1.
f: Mounting 1 A permanent magnet 3 is arranged below the ferromagnetic body 2. As the bimorph element 1 bends, the ferromagnetic body 2 comes into contact with the permanent magnet 3 and is attracted to it, whether or not a voltage is applied to bend the bimorph element 1 in the direction of the arrow shown by the solid line in the figure.

FIG. 7 explains the force at the tip of the bimorph element 1 during this process, and the horizontal axis shows the amount of deformation δ of the bimorph element 1,
The force f'x is shown on the vertical axis. In FIG. 7, a straight line a indicates the force generated by the bimorph element itself, and the force decreases linearly with deformation and becomes O when the maximum displacement δmax is reached. on the other hand.

The curved line represents the force by which the permanent magnet 3 draws the bimorph element 1 downward through the ferromagnetic material 2, and the force rapidly increases as the ferromagnetic material 2 approaches, reaching the maximum force fm when they come into contact. Therefore, the force at the tip of the bimorph element becomes a total composite of the force generated by the element itself and the force due to the action of the permanent magnet, and changes as shown by curve C in Figure 1. Therefore, even at the position of maximum deformation, the force fm of the permanent magnet acts downward. Furthermore, if a voltage is applied that causes the bimorph element 1 to bend in the direction of the broken line in FIG. It can be deformed in any direction. Note that 4 is a fixed support portion of the bimorph element 1.

[Problems to be Solved by the Invention] However, in general, it is necessary to strike a delicate balance between the force generated by the Guimorph element and the attractive force of the magnet, and drive it under a constant voltage condition.

There was a problem that required a lot of effort to make adjustments.

The present invention aims to solve such problems, and aims to provide a piezoelectric bimorph device that can adjust the driving conditions of the piezoelectric bimorph element with simple operations.

[Failure to solve the problem]

According to the present invention, a ferromagnetic metal is used as the intermediate metal plate of the piezoelectric bimorph element, and a permanent magnet is disposed adjacent to the piezoelectric bimorph element, so that the attractive force acting on the intermediate metal plate through the piezoelectric ceramic is applied to the piezoelectric bimorph element. The structure is used to reinforce the force when the piezoelectric bimorph element is deformed, and the reinforcing force can be continuously adjusted by making the permanent magnet movable along the plate surface when the piezoelectric bimorph element is deformed. It is characterized by the following.

〔Example〕

Two aspects of the present invention will be described in detail below.

FIG. 3 shows the structure of a piezoelectric bimorph element used in the present invention, in which an intermediate metal plate 7 is sandwiched between two ceramic thin plates 5 each having an electrode film 6 formed on its front and back surfaces. As the intermediate metal plate 7, a ferromagnetic material 9 such as permalloy, ferromagnetic amorphous, etc. is used.

FIG. 4 shows the basic configuration of the present invention, in which a permanent magnet 8 is movable along the plate surface when the piezoelectric bimorph element 1 is deformed.
are placed. By moving the magnet 8 in the direction of the arrow, the position where the magnet 8 acts on the bimorph element 1 can be adjusted, and the influence of the magnet 8 can be controlled. As a result, the reinforcing force of the bimorph element at maximum deformation can be controlled.

FIG. 5 shows this relationship, where the horizontal axis shows the distance from the bimorph fixing part to the length direction of the bimorph element, and the vertical axis shows the relationship between the three types of forces.

Curve 2 in the figure shows the force generated by the bimorph element, which is minimum at the tip and increases as it approaches the fixed part. The straight line d shows the force f-t that the magnet exerts on the tip of the bimorph element when the magnet is at any position X between 0 and 4. The force with which the magnet attracts the entire intermediate metal plate through the ceramic plate of the bimorph element is constant regardless of the position of the bimorph element. shall be. Force F is applied at a distance of X from the fixed part. When suctioning with
The force acting at the position =to is approximately a lever.

This straight line becomes straight line d in FIG.

That is, by adjusting the position X of the permanent magnet, the force f that reinforces the tip of the bimorph element at maximum deformation can be adjusted.

FIG. 1 shows a specific example of a piezoelectric bimorph device according to the invention. Here, a case will be described in which the piezoelectric bimorph element 1 is used as a piezoelectric relay by opening and closing the contacts of the relay. The piezoelectric bimorph element 1 is housed in a case 9 made of resin. The case 9 consists of a case body 91 and a lid body 92,
The fixed end of the piezoelectric Guimorph element 1 is sandwiched and fixed between one end edge of the case body 91 and one end edge of the lid body 92. Two contacts 10 are provided on the other end wall of the case body 91.
a and 10b are inserted, and the piezoelectric bimorph element 1 is arranged so that the contacts IQa and 10be open and close at their free ends. The contacts 10a and 10b are connected to various electric circuits (
(not shown) are connected.

Of course, the contact point 10a of the free end of the piezoelectric bimorph element 1
, 10b, the electrode 5 is not formed in the portion that engages with the electrodes 10b. On both side walls of the case body 91, an arc-shaped elongated hole 91a is formed in one side wall, and a groove 91 of the same shape is formed in the inner wall of the other side wall.
b is formed. As shown in FIG. 2, these elongated holes 91a and grooves 91b are formed along the plate surface of the piezoelectric bimorph element 1 when it is deformed, and the magnet 8 magnetized in a direction perpendicular to the long axis direction. It will be installed. The magnet 8 has a sliding guide shaft 81 at one end. The other end has a guide shaft 82 which also serves as a knob, and is slidable along the elongated hole 91a and the groove 91b. This makes it possible to easily adjust the position xf of the magnet 8 mentioned above. Of course, the present invention is not limited to the piezoelectric actuator shown in the drawings, and can be applied to various applications.

〔Effect of the invention〕

As described above, according to the present invention, by using a ferromagnetic material for the intermediate metal plate of the piezoelectric bimorph element, it can be attracted to any position by a permanent magnet, and the structure is simplified. Furthermore, by making it possible to move the permanent magnet along the plate surface when the piezoelectric bimorph element is deformed, it has become possible to provide a piezoelectric bimorph device that has the advantage of being able to adjust the reinforcing force.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the present invention in an exploded perspective view. FIG. 2 is a longitudinal cross-sectional view of the device shown in FIG. 1, FIG. 3 is an exploded perspective view of a piezoelectric bimorph element used in the present invention, FIG. 4 is a diagram showing the basic configuration of the present invention, and FIG. 5 is a diagram showing its operation. A piezoelectric bimorph element length-force characteristic diagram for explanation, and FIG. 6 is a diagram showing the basic configuration of a conventional example. FIG. 7 is a characteristic diagram of deformation versus force for explaining the effect. In the figure, 1 is a piezoelectric bimorph element, 5 is a ceramic thin plate,
6 is an electrode, 7 is an intermediate metal plate, 8 is a permanent magnet, 9 is a case, and 10a and 10b are contacts. Figure 3A Figure 5Figure 2

Claims (1)

[Claims] 1. By using a ferromagnetic metal as the intermediate metal plate of the piezoelectric bimorph element and arranging a permanent magnet adjacent to the piezoelectric bimorph element, the attractive force acting on the intermediate metal plate through the piezoelectric ceramic is applied to the piezoelectric bimorph element. The structure is used for reinforcing force during deformation, and the reinforcing force can be continuously adjusted by making the permanent magnet movable along the plate surface of the piezoelectric bimorph element when it is deformed. A piezoelectric bimorph device characterized by: