JP2000217374A - Piezoelectric actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a piezoelectric actuator excellent in oscillation characteristics with high machinability by supporting the peripheral edge of a diaphragm with a metal ring and encasing it in a synthetic resin case. SOLUTION: A piezoelectric actuator comprises a diaphragm 3 pasted with a piezoelectric element 1, a pair of metallic inner rings 5, 6 supporting the peripheral edge of the diaphragm 2, an upper synthetic resin case 3 having a groove 7 to be fitted with the inner ring 5, and a lower synthetic resin case 4 having a groove 8 to be fitted with the inner ring 6. After being fitted with the inner rings 5, 6, respectively, in the grooves 7, 8, the upper and lower cases 3, 4 are jointed to clamp the diaphragm 2. According to the method, a piezoelectric actuator having stabilized oscillation characteristics can be manufactured with high machinability while sustaining a sufficient machining accuracy of the diaphragm clamping face without causing abrasion on the clamping face.

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.

As shown in FIG. 5, a conventional piezoelectric actuator has a configuration in which 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. The lower case 4 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. Also, the coefficient of thermal expansion of the resin is far apart from the material of the diaphragm 2,
There is a problem that the sandwiching state of the diaphragm 2 changes depending on the temperature and the characteristics change.

[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 processability, the characteristics will change due to poor processing accuracy or wear of the clamping surface of the diaphragm. It is to be.

[0008]

SUMMARY OF THE INVENTION The present invention is intended to prevent the characteristics from changing even when the vibration plate to which the piezoelectric element is attached is installed in a case, even if the case is made of synthetic resin. After the peripheral edge of the diaphragm is supported by a metal ring, the metal ring is placed in a synthetic resin case.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In a piezoelectric actuator according to the present invention, as shown in FIGS. 1 and 2, a vibrating plate 2 to which a piezoelectric element 1 is attached and a pair of metal members sandwiching the peripheral edge of the vibrating plate 2 are provided. Inner ring 5, 6 and a synthetic resin upper case 3 in which a groove 7 in which one inner ring 5 fits is formed, and a synthetic resin in which a groove 8 in which the other inner ring 6 fits are formed. And the lower case 4.

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.

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 formed by the inner ring 5 made of metal. 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. Further, the thermal expansion coefficients of the inner rings 5 and 6 can be made substantially the same as those of the diaphragm 2, and it is possible to prevent a change in the vibration characteristics due to a change in the sandwiching state of the diaphragm 2 due to the temperature.

FIG. 3 shows another example of the structure of the piezoelectric actuator according to the present invention. In this case, the peripheral edge 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 in 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 plate 2 by caulking between the upper case 3 and the lower case 4.

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.

[0019]

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. With such a configuration, there is an advantage that a product having stable vibration characteristics can be manufactured with good workability.

[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. (72) Inventor Junichi Suzuka 14-18 Takatsuji-cho, Mizuho-ku, Nagoya-shi, Aichi Prefecture Inside Japan Specialty Ceramics Co., Ltd. No. 18 F-term in Japan Special Ceramics Co., Ltd. (reference) 3H075 AA18 BB04 CC32 CC40 DA05 DB02 DB49 5J108 AA06 CC02 GG02 GG18 KK03

Claims (4)

[Claims] 1. A piezoelectric actuator in which 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. 2. The piezoelectric actuator according to claim 1, wherein an upper case and a lower case are assembled so that a peripheral edge of the diaphragm is sandwiched between a pair of metal rings. 3. One of the metal rings is provided with a wall projecting from the periphery thereof, and the diaphragm and the other metal ring are placed on the ring, and the end of the wall is bent. 2. The piezoelectric actuator according to claim 1, wherein the diaphragm is clamped between a pair of metal rings by swaging. 4. 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.