JP2000217373A - Piezoelectric actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a piezoelectric actuator in which machinning precision is not varied, the support part of a diaphragm is not worn and the holding state of the diaphragm is not changed by a temperature and which has stable vibration characteristics with satisfactory machinability. SOLUTION: The circumferential edge of a diaphragm 2 to which a piezoelectric device 1 is attached is supported by metal inner rings 5 and 6 which are placed in synthetic resin cases 3 and 4. Material which has a thermal expansion coefficient equal to or approximately same as that of the material of the diaphragm is used as the material of the metal rings.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric actuator in which a diaphragm on which a piezoelectric element is mounted is provided in a case.

[0002]

2. Description of the Related Art In general, a piezoelectric actuator of this type uses a thermo-resistive element provided in a pair of left and right gas flows in a gas passage when an angular velocity acts on a sensor body. The sensor body is an ultra-small gas type angular velocity sensor formed by micromachining, which is electrically detected as a change in resistance and determines the magnitude and direction of the angular velocity at that time, and it is located in the gas passage. It is used as a pump to supply a constant gas flow.

[0003] However, in such a piezoelectric type actuator, extremely high processing accuracy is required to stabilize the operation characteristics.

In a conventional piezoelectric actuator, as shown in FIG. 5, a peripheral edge of a diaphragm 2 to which a piezoelectric element 1 is attached is sandwiched between an upper case 3 and a lower case 4 formed by pressing or the like. In this manner, the upper case 3 and the lower case 4 are connected by caulking, welding, screwing, or the like.

At this time, the vibration characteristics of the diaphragm 2 are slightly changed depending on the state of the connection between the upper case 3 and the lower case 4. Therefore, each of the cases 3 and 4 is precisely machined with metal. Workability is poor.

In the case where the upper case 3 and the lower case 4 are formed of synthetic resin in order to improve the workability, the processing accuracy of the surface holding the diaphragm 2 is deteriorated, and the characteristics are varied. The characteristics change due to wear of the holding surface due to the vibration of No. 2. At that time,
The thermal expansion coefficients of the upper case 3 and the lower case 4 made of synthetic resin are far apart from the material of the diaphragm 2, and there is a problem that the sandwiching state of the diaphragm 2 changes depending on the temperature and the characteristics change. is there.

[0007]

The problem to be solved is that the upper case and the lower case, which hold the periphery of the diaphragm on which the piezoelectric element is mounted, are precisely machined with metal so that there is no variation in characteristics. If the upper case and the lower case are molded with synthetic resin to improve the workability, the processing accuracy of the clamping surface of the diaphragm will be poor or worn, and especially the vibration That is, the thermal expansion coefficient is far apart from that of the plate, and the sandwiching state of the diaphragm changes depending on the temperature, and the vibration characteristics change.

[0008]

According to the present invention, when a diaphragm to which a piezoelectric element is attached is installed in a case, even if the case is made of synthetic resin, the processing accuracy of the clamping surface of the diaphragm is poor. In order to prevent the vibration characteristics from changing due to wear or the temperature changing the sandwiching state of the diaphragm, the peripheral edge of the diaphragm is supported by a metal ring, and the metal The ring is placed in a synthetic resin case, and the metal ring is made of the same or almost the same thermal expansion coefficient as the diaphragm.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In a piezoelectric actuator according to the present invention, as shown in FIGS. 1 and 2, a diaphragm 2 on which a film-like piezoelectric element 1 is adhered and a peripheral edge of the diaphragm 2 are sandwiched. A pair of metal inner rings 5, 6, a synthetic resin upper case 3 in which a groove 7 in which one inner ring 5 is fitted and a groove 8 in which the other inner ring 6 is fitted are formed. And a lower case 4 made of synthetic resin.

Here, a configuration in which a piezoelectric actuator is used as a pump is shown. In the upper case 3, a gas inlet 9 and a gas outlet 10 are provided.
A gas chamber 11 is formed inside the case where the upper case 3 and the lower case 4 are assembled. In the figure, reference numeral 12 denotes an external lead hole of the lead 13 of the piezoelectric element 1.

In the piezoelectric actuator having such a configuration, the inner ring 5 is fitted into the groove 7 on the upper case 3 side, and the inner ring 6 is fitted into the groove 8 on the lower case 4 side. The upper case 3 and the lower case 4 are joined by holding the diaphragm 2 therebetween.

At this time, if the inner ring 5 is inserted into the groove 7 on the upper case 3 side and the inner ring 6 is inserted into the groove 8 on the lower case 4 in advance, it is possible to assemble at the time of assembling. Workability is improved.

The upper case 3 and the lower case 4 are joined by bonding with an adhesive, ultrasonic welding, heat caulking, screwing, or the like.

In such a case, in particular, in the present invention, the material of the inner rings 5 and 6 has the same or almost the same thermal expansion coefficient as that of the diaphragm 2.

For example, the diaphragm 2 to which the piezoelectric element 1 made of ceramic (PZT) is adhered is made of 42% Ni-58.
%, The inner rings 5 and 6 are formed of the same Ni-Fe alloy material.

As described above, according to the present invention, when the diaphragm 2 is installed in the case composed of the upper case 3 and the lower case 4 made of synthetic resin, the peripheral edge of the diaphragm 2 is made of a metal inner ring 5, 6 so that the processing accuracy of the holding surface of the diaphragm 2 is sufficiently maintained.
A material having stable vibration characteristics can be manufactured with good workability without causing wear on the holding surface. In particular, the thermal expansion coefficient of the inner rings 5 and 6 can be made the same or almost the same as that of the diaphragm 2, and it is possible to prevent the vibrating characteristic from being significantly changed by changing the sandwiching state of the diaphragm 2 depending on temperature. Can be prevented.

FIG. 3 shows another example of the structure of the piezoelectric actuator according to the present invention. In this case, the peripheral portion of the diaphragm 2 is previously formed with a pair of metal inner rings 14 and 14.
What is clamped between 15 by caulking is placed in a case composed of an upper case 3 and a lower case 4 made of synthetic resin.

When the peripheral portion of the diaphragm 2 is sandwiched between the pair of inner rings 14 and 15, one of the inner rings 14 fitted into the groove 8 on the lower case 4 side has the peripheral portion as shown in FIG. The diaphragm 2 and the other inner ring 15 are placed on the inner ring 14 such that each end of the diaphragm 2 and the other inner ring 15 are in contact with the wall 16. The tip of the portion 16 is bent and swaged.

The groove 7 on the upper case 3 side and the lower case 4
The upper case 3 and the lower case 4 are assembled by fitting the inner rings 14 and 15 integrated so as to clamp the vibration 2 by caulking with the groove 8 on the side.

Therefore, according to this configuration, in particular, the one in which the peripheral portion of the diaphragm 2 is sandwiched between the pair of inner rings 14 and 15 by caulking in advance is assembled in the case, so that the diaphragm can be easily formed. The pinching state of the peripheral edge of No. 2 can be made constant, and those having stable vibration characteristics can be mass-produced with good workability.

Further, the diaphragm 2 is placed on the inner ring 14 without using the inner ring 15, and the end of the wall 16 is bent to form the diaphragm 2 on one inner ring 15 by caulking. If it is attached, the number of parts can be reduced.

[0022]

As described above, in the piezoelectric actuator according to the present invention, the peripheral edge of the vibration plate to which the piezoelectric element is attached is supported by a metal ring, and the metal ring is set in a synthetic resin case. It has a stable vibration characteristic without fluctuations in processing accuracy or wear of the supporting part of the diaphragm, and no change in the clamping state of the diaphragm due to temperature. It has the advantage that it can be manufactured well.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing one embodiment of a piezoelectric actuator according to the present invention.

FIG. 2 is an exploded perspective view of the piezoelectric actuator according to the embodiment.

FIG. 3 is a front sectional view showing another embodiment of the piezoelectric actuator according to the present invention.

FIG. 4 is a diagram showing a process of clamping a peripheral portion of the diaphragm between a pair of inner rings by caulking.

FIG. 5 is a front sectional view showing a conventional piezoelectric actuator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piezoelectric element 2 Diaphragm 3 Upper case 4 Lower case 5 Inner ring 6 Inner ring 9 Inlet 10 Outlet 14 Inner ring 15 Inner ring 16 Wall

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kiyoshi Kato 1-4-1 Chuo, Wako, Saitama Prefecture Inside Honda R & D Co., Ltd. (72) Inventor Shinsuke Hirayama 1-4-1 Chuo, Wako, Saitama No. Within Honda R & D Co., Ltd. No. 18 F-term in Japan Special Ceramics Co., Ltd. (reference) 3H075 AA18 BB04 CC14 CC32 DA05 DB02 5J108 AA06 CC02 GG02 GG08 GG10 GG18 KK03

Claims (3)

[Claims] A peripheral edge of a diaphragm to which a piezoelectric element is attached is supported by a metal ring, and the metal ring is set in a synthetic resin case.
A piezoelectric actuator, wherein the metal ring has the same or substantially the same thermal expansion coefficient as the diaphragm. 2. The piezoelectric actuator according to claim 1, wherein a peripheral edge of the diaphragm is sandwiched between a pair of metal rings. 3. The piezoelectric actuator according to claim 1, wherein the case has a sealed structure, and the case is provided with a gas inlet and a gas outlet and used as a pump.