JPS6230769Y2 - - Google Patents

Description

[Detailed Description of the Invention] An object of the present invention is to provide a voltage-driven so-called piezoelectric relay, which is small in size, has a large driving force, and has high reliability.

Figure 1 shows the basic structure and operating principle of a piezoelectric relay. In the figure, 1 is a so-called bimorph in which piezoelectric ceramics 1a and 1a' are bonded together, and is supported by a support portion 2 in a cantilever shape. Bimorph 1 above
A movable contact 4 is attached to the tip of the movable part via an insulating part 3, and when input voltage is applied from the lead wires 5, 5', the bimorph 1 is displaced as shown by the broken line, and the movable contact 4 is connected to the opposite contact 4. ′ is configured to make contact with the relay. Figure 2 shows a diagram of the principle of a cantilever bimorph used in piezoelectric relays. In the figure, L is the effective length of the cantilever beam, T is the thickness of the bimorph, and W is also the width. The displacement δ of the tip obtained by applying a voltage V to this bimorph is expressed by the following equation (1), where _d31 is the piezoelectric constant of the piezoelectric ceramic used for the bimorph.

δ=4・d ₃₁・V・(L/T) ² ...(1) Also, the driving force F is given by Y, where the Young's modulus of the piezoelectric ceramic used in the bimorph is F=1/2・d ₃₁・Y・V・W・T/L…(2).

As can be seen from equations (1) and (2), once the material constants and applied voltage are determined, the displacement δ and driving force F of the bimorph are determined by the length L, thickness T, and width W. Since the ratio of the thickness T has contradictory effects on the displacement δ and the force F, in order to obtain a sufficient displacement δ and force F, the width W must be increased, and the piezoelectric relay is configured. In this case, it had the disadvantage of being large in size. Furthermore, when the width W is increased, the width W cannot be ignored compared to the length L, and as shown in Fig. 3, a displacement d' occurs at the tip that curves in the width direction, resulting in unstable operation. It also had some drawbacks.

The present invention eliminates these conventional drawbacks and provides a compact and highly reliable piezoelectric relay, which will be explained below with reference to figures of embodiments.

FIG. 4 is a basic structural diagram showing an embodiment of a bimorph constituting a piezoelectric relay according to the present invention. As shown in the figure, piezoelectric ceramics 6a, 6a' and 7a, 7
The two bimorphs 6 and 7 formed by a' are fixed by a support part 8 so as to overlap in the width direction in a cantilever shape, and are attached so as to be in contact with each other at the movable part. In the figure, members 9 and 9' are used to improve the sliding of the contact portion. The structure of the tip of the movable part of this bimorph is shown in Figure 5a. When the bimorphs are driven by applying an input voltage, the two bimorphs 6 and 7 are displaced in the same direction.
The state shown in FIG. 5b is reached, and forces are applied while causing a deviation d at the tip. FIG. 6 shows a case where two bimorphs 6 and 7 are connected by a connecting member 10, and is a second embodiment of the present invention. Further, FIG. 7 shows a third embodiment of the present invention using a connecting member 11 having movable parts 11a and 11a', and in this case, the effect is the same even if a deformable connecting member is used.

Although the piezoelectric relays of the present invention shown in FIGS. 4 to 7 are examples in which two bimorphs are used, it is also possible to increase the number of bimorphs.

In the piezoelectric relay of this invention, if each bimorph used has the same shape, the overall displacement δ is as shown in (1) above.
Although it is the same as the formula, the driving force F is ideally applied by the number n of bimorphs, and can be n times that when one bimorph is used. Therefore, the width W
The driving force is equivalent to multiplying by n. Generally, the thickness T of a bimorph is several tenths of the width W, and the increase in overall thickness due to overlapping in the thickness direction is small, so the overall size is small and has sufficient driving force. is obtained. Also, the width W
Since the ratio between L and L is sufficient, stable operation can be obtained without causing the bending phenomenon in the width direction as shown in FIG.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the basic structure and operating principle of a piezoelectric relay, Figure 2 is a perspective view explaining the principle of the bimorph used in the piezoelectric relay, and Figure 3 is an explanation of the bending phenomenon of the tip of the bimorph. 4 is a basic structural diagram showing an embodiment of the bimorph constituting the piezoelectric relay according to the present invention, and FIGS. 5a and 5b are
is an operational explanatory diagram showing the structure of the tip portion of the bimorph, and FIGS.
FIG. 7 is a structural diagram of a bimorph showing a third example. 6, 7... Bimorph, 10, 11... Connecting member, 11a, 11a'... Movable part.

Claims (1)

[Claims for Utility Model Registration] (1) A plurality of bimorphs fixed in a cantilever shape so as to be displaced in the same direction are brought into contact without being fixed by their movable parts, so that the forces obtained with displacement are added together. Piezoelectric relay configured. (2) A piezoelectric relay according to claim (1) of the utility model registration, in which movable parts of a plurality of bimorphs are connected by a connecting member. (3) The piezoelectric relay according to claim (2), which uses a member that is deformable or has a movable part as a connecting member.