JPH0427079Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a piezoelectric relay using a piezoelectric element that generates distortion when a voltage is applied.

[Conventional technology]

Conventional piezoelectric relays of this type are described, for example, in Japanese Patent Application No. 59-223224 filed by the same applicant (Japanese Patent Application Laid-Open No.
61-101934) has been proposed. A conventional piezoelectric relay will be described with reference to FIG. 2, which shows a contact driving section, which is the main part thereof.

The contact drive unit 20 is a piezoelectric drive unit in which a plurality of piezoelectric elements are integrally stacked such that internal electrodes are alternately located between them, and mechanical strain is generated in which the piezoelectric elements expand and contract in the stacking direction, that is, the longitudinal direction, due to an electric field. body 21, driver 22, drive board 23, and fixed body 2
4 and a displacement amplifying mechanism 25. Drive element 22
is fixed to one end of the piezoelectric drive body 21 in the longitudinal direction, and the fixed body 24 connects the piezoelectric drive body 21 to the drive substrate 23.
Fixed to. The displacement magnifying mechanism 25 includes a hinge spring 2
51, 252, 257, 258, arm bodies 253, 255, 256 coupled to these hinge springs 251, 252, 257, 258, and drive protrusion 254
It has a juxtaposition of. The hinge spring 251 has one end fixed to the drive board 23 and the other end fixed to the arm body 253 to form a fulcrum of the arm body 253. Hinge spring 25
2 has both ends fixed to the arm body 253 and the arm body 255, and has the role of transmitting displacement. Similarly, the hinge spring 257 has both ends connected to an arm body 255 and an arm body 256.
Both ends of the hinge spring 258 are fixed to the arm body 256 and the drive board 23, respectively. arm body 253
is in contact with the drive element 22 at its intermediate portion. Arm 256 has a drive protrusion 254 that drives a contact (not shown). Hinge springs 251, 25
2,257,258 are arm bodies 253, 2 with central axes on approximately the same plane and leaf spring surfaces approximately parallel to each other.
Together with 55 and 256, the displacement magnification mechanism 25 is formed.

When a voltage is applied to the piezoelectric drive body 21, the displacement of the piezoelectric drive body 21 is transmitted to the displacement magnification mechanism 25 via the drive element 22, and the drive protrusion 254 connects a movable contact (not shown) to a fixed contact arranged oppositely. (not shown) to bring them into contact and close the circuit. When the applied voltage is removed, the original state is restored and the movable contact is separated from the fixed contact. The amount of displacement of the piezoelectric drive body 21 is per applied electric field of 1000V/mm
10 μm, whereas the displacement amount of the drive protrusion 254 required as a relay is 0.5 to 1 mm, so the magnification rate of the displacement magnification mechanism 25 is set to 50 to 100 times. Each component of the contact drive unit 20, except for the piezoelectric drive body 21 and the drive protrusion 254, is generally made of a metal material with a different coefficient of thermal expansion from the piezoelectric drive body 21, which is a ceramic material. , the difference between the amount of linear expansion of the piezoelectric drive body 21 and the amount of linear expansion of the metal material is magnified by the displacement magnification mechanism with a high magnification rate and transmitted to the drive protrusion, changing the characteristics of the relay.

On the other hand, a piezoelectric relay equipped with a temperature correction mechanism for eliminating the influence of this temperature change has been proposed by the same applicant in Japanese Patent Application No. 128992/1982 (see Japanese Patent Application Laid-Open No. 7530/1982). The principle of the temperature correction mechanism will be explained with reference to FIG. In this figure, the same constituent members as those in FIG. 2 are designated by the same reference numerals, and their explanations will be omitted. The coefficient of thermal expansion of the piezoelectric drive body 21 is α ₁ , and the coefficient of thermal expansion of the metal material forming the contact drive unit 20 excluding the temperature correction member 14 , drive protrusion 254 and piezoelectric drive body 21 is α ₂ . The temperature correction member 14 has the same shape as the fixed body 24 in FIG. 2, but is made of a metal material having a coefficient of thermal expansion α ₃ different from coefficients of thermal expansion α ₁ and α ₂ , and has a fixed point A in FIG. 3. It is fixed to the drive board 23 at the position shown by. Assuming that the length of the piezoelectric driver 21 is ₁ , the length from the fixed point A of the temperature correction member 14 to the fixed end of the piezoelectric driver 21 is ₃ , and ₁ + ₃ = ₂ , the following equation is used for temperature correction. ₃ α ₃ = ₂ α ₂ − ₁ α ₁ ...(1) The thermal expansion coefficient α ₃ of the temperature compensation member 14 is set to satisfy the following.
All you have to do is set the length to ₃ .

[Problem that the invention attempts to solve]

The principle of temperature correction is expressed by equation (1), but in order to realize this as a temperature correction mechanism, the material of the temperature correction member must be determined in advance, and the following equation obtained by modifying equation (1) should be used. ₃ = ₁ (α ₂ - α ₁ ) / (α ₃ - α ₂ ) (however, ₂ = ₁ + ₃ ) ... At the fixed point A in Figure 3, ensure a length ₃ that satisfies (2). Temperature correction member 14 is connected to drive board 23
must be firmly attached to. Welding can be considered as a means of this fixation, but with resistance welding it is difficult to set the welding point precisely, and the length that satisfies equation (2) is difficult.
₃ is difficult to obtain reliably. Furthermore, since the temperature compensation member 14 also has the function of the fixed body 24 in FIG. Penetration of light into the driving substrate 23 becomes insufficient, and sufficient welding strength cannot be obtained. In any of these welding methods, the effective length ₃ of the temperature compensation member 14
There was a problem in that it was not possible to satisfy both the requirements of securing the desired temperature and sufficient welding strength.

[Means for solving problems]

The piezoelectric relay of the present invention has a plurality of piezoelectric elements that generate mechanical strain due to an applied voltage, which are laminated together so that a plurality of internal electrodes are alternately located between them, and a driver is provided at one end to create a free relay. a piezoelectric drive body having one end and the other end being a fixed end; a drive board fixing the fixed end of the piezoelectric drive body; one end fixed to the drive board via a hinge spring and coupled to the hinge spring; a displacement magnifying mechanism having an arm that contacts the driver; and a drive protrusion that presses the arm of the driver to expand the displacement of the driver based on this principle and moves by this displacement; a temperature correction member having a fixed surface on which a fixed end is installed, a fixed surface fixed to the drive board, and an escape groove provided on the fixed surface; The drive board is fixed to the drive board on the boundary line between the drive board and the drive board.

〔Example〕

Next, the present invention will be described with reference to the drawings.

In FIGS. 1A and 1B showing an embodiment of the present invention, the same constituent members as in FIGS. 2 and 3 are designated by the same reference numerals, and their explanations will be omitted.
The difference between FIG. 1a and FIG. 2 is in the temperature correction member 44. The temperature correction member 44 has a fixed surface 441 on which the fixed end of the piezoelectric drive body 21 is installed.
and a fixing surface 442 for fixing to the drive board 23.
and an escape groove 444 extending parallel to the fixing surface 442 in the direction of the fixing surface 441 from a position a length ₃ from the fixing surface 441 on the fixing surface 442 . The thermal expansion coefficients of the piezoelectric drive body 21, displacement magnification mechanism 25, and temperature correction member 44 are α ₁ , α ₂ , and α _{3 ,} respectively, and the longitudinal length of the piezoelectric drive body 21 is
_1. Fixed surface 441 and fixed surface 4 of temperature correction member 44
42, the length between the relief groove 444 and the boundary line 445
₃ and the length ₂ = ₁ + ₃ , the length ₃ can be calculated from the above equation (1) ₃ α ₃ = ₂ α ₂ − ₁ α ₁ , and furthermore, this
_{Equation (2) obtained by transforming Equation (1) = 1 (} α ₂ −
It is determined to satisfy α ₁ )/(α ₃ −α ₂ ) (where ₂ = ₁ + ₃ ). For example, the drive element 22, the drive board 23, and the displacement magnifying mechanism 25 are made of Invar material with a small coefficient of thermal expansion α (α=1×10 ⁻⁶ /°C approximately), and the temperature correction member 44 is Stainless steel with a large expansion coefficient α (α=17×10 ^-6 /℃
degree), etc. Temperature correction member 44
In FIG. 1b, the fixed surface 442 slides along the guide surface 231 provided on the drive board 23, and the fixed surface 441 presses the piezoelectric drive body 21 and the driver 22 toward the arm body 253. The position indicated by W, that is, the fixed surface 442 of the temperature correction member 44 and the relief groove 4
On the boundary line 445 with 44, it is fixed to the drive board 23 by a method such as resistance welding. The effective distance ₃ for temperature correction is fixed surface 441 - boundary line 44
Since it is determined by the distance between the two parts, if the fixing surface including the boundary 445 is fixed, an appropriate length ₃ can be obtained reliably.

Note that the escape groove 444 is not limited to the illustrated shape and size, and may be any shape as long as it has a fixing strength that can withstand the stress generated by the piezoelectric drive body 21.

[Effect of idea]

As explained above, the present invention has a piezoelectric drive body,
It has an appropriate thermal expansion coefficient and dimensions to correct the amount of displacement due to thermal expansion deformation of the drive board and displacement magnification mechanism, and also has a fixed surface on which the fixed end of the piezoelectric drive body is installed and a fixed surface that is fixed to the drive board. A temperature correction member having a relief groove provided therein is provided, and this temperature correction member is fixed to the drive board on the boundary line between the fixation surface and the relief groove, or on a surface including the boundary line, thereby achieving sufficient fixation strength. This has the effect of providing a piezoelectric relay that achieves reliable temperature correction, can be used over a wide temperature range, and has excellent temperature characteristics.

[Brief explanation of the drawing]

FIG. 1a is a partially exploded perspective view of an embodiment of the present invention, FIG. 1b is a sectional view showing details of the contact drive section in FIG. 1a, FIG. FIG. 3 is a diagram showing the principle of temperature correction in a piezoelectric relay. 40...Contact drive unit, 21...Piezoelectric drive body, 2
2... Drive element, 23... Drive board, 231... Guide surface, 24... Fixed body, 25... Displacement magnification mechanism,
251, 252, 257, 258... Hinge spring, 253, 255, 256... Arm body, 254...
...Drive protrusion, 44...Temperature correction member, 441...
Fixed surface, 442...Fixed surface, 444...Escape groove,
445...boundary line.

Claims (1)

[Claims for Utility Model Registration] (1) A plurality of piezoelectric elements that generate mechanical strain due to an applied voltage are integrally stacked such that a plurality of internal electrodes are alternately located between them, and a drive element is attached to one end. a piezoelectric drive body having a free end and a fixed end; a drive board fixing the fixed end of the piezoelectric drive body; one end fixed to the drive board via a hinge spring; a displacement amplifying mechanism having an arm that is coupled to and contacts the driver, and a drive protrusion in which the driver presses the arm to expand the displacement of the driver based on this principle and moves by this displacement; a temperature correction member having a fixing surface on which a fixed end of the piezoelectric drive body is installed, a fixing surface fixing to the drive board, and an escape groove provided in the fixing surface; A piezoelectric relay, characterized in that the piezoelectric relay is fixed to the drive board on the boundary line between the surface and the relief groove. (2) The thermal expansion coefficients of the piezoelectric drive body, displacement magnification mechanism, and temperature correction member are α ₁ , α _{2 ,} and α _{3 ,} respectively.
The length in the longitudinal direction of the piezoelectric drive body _{is 1} ,
When the length from the fixed surface of the temperature compensation member to the boundary line between the fixed surface and the escape groove _{is 3} , and the length ₂ = ₁ + ₃ , the thermal expansion coefficient α ₃ and the length ₃ are ₃ . α ₃ = ₂ α ₂ − ₁
The piezoelectric relay according to claim 1, which satisfies _α1 .