JPH0584154B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electrostrictive motor in which an electrostrictive element deforms to generate rotational force when a signal is input.

(Conventional configuration and its problems) In recent years, electrostrictive motors that generate rotational force using surface waves generated on the surface of a disc-shaped electrostrictive element when a high-frequency signal is input have been prototyped and researched. Although the results have been introduced in the literature (Japanese Patent Application Laid-Open No. 58-148682), no mass-produced commercial product has been announced yet, and
There is also no literature disclosing a configuration suitable for mass production.

(Object of the invention) The object of the invention is to:
The purpose of the present invention is to provide an electrostrictive motor with excellent mass productivity.

(Structure of the Invention) According to the present invention, when a high-frequency signal is input through a printed wiring board and an electrostrictive element fixed to the printed wiring board via a cushion material vibrates, the surface of an elastic body fixed to the electrostrictive element vibrates. A transverse traveling wave in the circumferential direction is generated, and a rotary plate fixed to one end of the output shaft and pressed against an elastic body by a spring means attached to the output shaft rotates in the circumferential direction.

(Description of Examples) Examples of the present invention will be described below with reference to the drawings.

FIG. 1 shows a sectional view of an electrostrictive motor according to an embodiment of the present invention, where 10 is a housing of the electrostrictive motor having a recess 10a formed in the center of the upper surface, and 11 is a terminal portion 11a and the terminal. The printed wiring board 11 is an annular printed wiring board having copper foil parts 11b, 11c, and 11d (see FIG. 2) provided on a portion 11a, and is fixed to the upper part of the casing 10. 12 is an annular cushion material made of an elastic material such as felt or sponge, which is adhered and fixed to the lower surface of the printed wiring board 11; 12 surface electrode parts e, f, g,
This is an annular electrostrictive element made of lead zirconate titanate, etc., with h, i, j, k, l, m, n, o, and p provided separately and one back electrode section on the back surface. The strain element 13 is bonded and fixed to the cushion material 12 in a deformable state, and the surface electrode parts e to j are connected to the copper foil part 11c via jumper wires 13a.
The front electrode parts k to p are connected to the copper foil part 11b via the jumper wire 13a, and the back electrode part is connected to the copper foil part 11d via the jumper wire 13b, and the terminal part 11a of the printed wiring board 11 is connected to the copper foil part 11b. By applying a high frequency signal to the copper foil parts 11b, 11c and 11d, each surface electrode part e, f, g, h, i, j,
When a positive signal is input to each of k, l, m, n, o, and p, and a negative signal is input to the back electrode part,
The surface electrode portions e, k, g, m, i and o of the electrostrictive element 13 contract in the circumferential direction as shown by the arrows, and the surface electrode portions f, l, h, n, j and p
extends in the circumferential direction as shown by the arrow. 14 is an annular elastic body made of metal such as steel or brass and is bonded to the surface of the electrostrictive element 13; 15 is an annular facing portion 16 made of resin or the like having a large coefficient of friction and excellent wear resistance; 17 is an output shaft to which the rotary plate 15 is fitted on one end; 18 is a ball with the middle part of the output shaft 17 rotatably supported on the bottom surface of the recess 10a of the housing 10; Bearing, 19 is a retaining ring fitted to the output shaft 17, 20
is a compression coil spring interposed between the ball bearing 18 and the retaining ring 19, and this compression coil spring 2
The output shaft 17 is urged upward in the drawing by a tensile force of 0, and the facing portion 16 of the rotary plate 15 is brought into pressure contact with the elastic body 14. A bottom plate 21 is fitted to the bottom of the housing 10, and this bottom plate 21 prevents foreign matter from entering the inside of the housing 10.

In this embodiment configured in this way, a high frequency signal is applied between the copper foil section 11b and the copper foil section 11d through the terminal section 11a to which the conductor from the high frequency power supply section is connected, and a high frequency signal is applied between the copper foil section 11c and the copper foil section 11d. Foil part 11d
When a high frequency signal with a phase shift of 90 degrees from this high frequency signal is applied between the two, the electrostrictive element 13 vibrates in the circumferential direction, and the lower surface of the elastic body 14 integrally bonded to the electrostrictive element Displaces in the vertical direction. Then, three peaks and three valleys are formed on the lower surface of the elastic body 14, and the three peaks and three valleys generate a traveling transverse wave that rotates in the circumferential direction, and presses against the elastic body 14. Since the facing portion 16 is rotated in the circumferential direction while being supported at three points, the rotary plate 15 rotates in the circumferential direction together with the output shaft 17. Incidentally, the rotational force transmitted from the elastic body 14 to the facing portion 16 is determined by the frictional force between the elastic body 14 and the facing portion 16; Since it is determined by the coefficient of friction and the contact pressure between them, that is, the tension force of the compression coil spring 20, the facing portion 16 is formed of a material with a high coefficient of friction with respect to the material of the elastic body 14, and If the facing part 16 is strongly pressed, the output shaft 17
When a load is applied to the motor, it is possible to output a considerable amount of rotational force even if braking is applied to the rotation. That is, the output torque of the electrostrictive motor changes depending on the tension force of the compression coil spring 20. If it is too low, almost no rotational force is output, and if it is too large, the rotational force is easily output, but the surface of the elastic body 14 The rotation of the output shaft slows down because the amplitude of the traveling transverse wave generated in the output shaft is compressed and reduced. Therefore, in order to obtain the target output rotation speed and rotational force, it is necessary to maintain the pressure of the compression coil spring 20 at a constant value, which will improve the performance of the mass-produced motor.
This is an important condition for ensuring quality.

FIG. 3 shows the configuration of another embodiment of the present invention, in which the same reference numerals as those in FIG. The casing, 23, has a ball bearing 18 in the center.
24 is the terminal part 24
This printed wiring board 24 is a disk-shaped printed wiring board provided with a copper foil part (not shown) and a cushion material 12, an electrostrictive element 13, and an elastic body 14 are sequentially adhered and fixed to the upper surface of the printed wiring board 24. In addition, the surface electrode portions e to j of the electrostrictive element 13 are connected to one copper foil portion via the jumper wire 13a, and the surface electrode portion k of the electrostrictive element 13 is connected to one copper foil portion via the jumper wire 13a.
These are fixed to the lower part of the casing 22, with the electrodes connected to other copper foil parts via jumper wires 13a and the back electrodes connected to other copper foil parts via jumper wires 13b. 25 has a recess 2 in the center
An annular facing portion 16 is bonded to the peripheral edge of the lower surface of the rotary plate 25. Reference numeral 26 denotes a compression coil spring interposed between the ball bearing 18 and the bottom surface of the recess 25a of the rotary plate 25. The tension force of the compression coil spring 26 urges the output shaft 17 downward in the figure, causing it to rotate. Board 25
The facing portion 16 is brought into pressure contact with the elastic body 14.

In this embodiment configured in this way, a high frequency signal is applied between the two terminals through the terminal section 24a to which the conductor from the high frequency power supply section is connected, and
When a high frequency signal with a phase shift of 90 degrees from this high frequency signal is applied between the other two terminals, the electrostrictive element 13 vibrates in the circumferential direction, and the elastic body bonded integrally to the electrostrictive element 13 vibrates in the circumferential direction. The lower surface of 14 is displaced in the vertical direction. Then, there are three peaks and three peaks on the bottom surface of the elastic body 14.
Three valleys were formed, and three mountains and three valleys were formed.
A traveling transverse wave is generated in which the two valleys rotate in the circumferential direction, and the facing portion 1 is in pressure contact with the elastic body 14.
6 is rotated in the circumferential direction while being supported at three points, the rotating plate 25 rotates in the circumferential direction together with the output shaft 17.

(Effects of the Invention) As explained above, according to the present invention, the contact pressure between the facing portion and the elastic body, which determines the output rotational speed and rotational force of the electrostrictive motor, is set by the compression coil spring. , compared to leaf springs, etc., the amount of spring deflection is greater, and the pressure setting is stable, and the output performance of the motor, which is determined by the motor's rotational force and rotation speed, is also kept stable, which improves performance and quality. It has the advantage of being able to mass-produce stable electrostrictive motors. or,
The compression coil spring is built inside the annular electrostrictive element and the annular elastic body, and a long compression coil spring can be used without protruding out of the housing, making it easier to attach to various devices. There is an advantage that a motor with good usability can be realized while maintaining high performance.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an electrostrictive motor in one embodiment of the present invention, FIG. 2 is a polarization/wiring diagram of an electrostrictive element in one embodiment of the present invention, and FIG. 3 is a diagram of another embodiment of the present invention. FIG. 2 is a cross-sectional view of an electrostrictive motor. 10, 22... Housing, 11, 24... Printed wiring board, 12... Cushion material, 13... Electrostrictive element, 14... Elastic body, 15, 25... Rotating plate, 1
7... Output shaft, 18... Bearing, 20, 26... Compression coil spring (spring means).

Claims (1)

[Scope of Claims] 1. A printed wiring board fixed to a housing, an electrostrictive element fixed to the printed wiring board via a cushion material, an elastic body fixed to the surface of the electrostrictive element, and an output shaft. A fixed rotating plate; and a coil spring attached to a position inside the electrostrictive element and the elastic body of the output shaft to press the rotating plate into contact with the elastic body. electrostrictive motor.