JPS62181682A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To simplify and miniaturize structure, and to improve response by providing a positioning means detecting the rotational position of a rotor and conducting positioning. CONSTITUTION:When two-phase AC voltage, phase thereof differs only by pi/2, is each applied to piezoelectric bodies 2, 3, the waves of progressive mechanical strain are generated in a stator 4. When a rotor 8 brought into pressure- contact with the stator 4 is turned and a permanent magnet 12 mounted to the outer circumferential surface of the rotor 8 is positioned where faced oppositely to a magnetic induction element 13, electrical pulses are generated. When the rise edge of the electrical pulses is detected and two-phase AC voltage applied to the piezoelectric bodies 2, 3 is interrupted in a circuit manner at that time, the rotor 8 is stopped instantaneously by large frictional force between a lining material 7 and a ring-shaped projection section 1a.

Description

[Detailed description of the invention] Industrial applications The present invention relates to an ultrasonic motor.

Conventional technology Conventionally, there have been stepping motors, DC servo motors, etc. as positioning actuators, and these are widely used in industry. In the case of suspension actuators, positioning actuators such as stepping motors and DC servo motors have slow response (
In the case of a stepping motor, the response is slow because it advances one step at a time to the target value, and there is no staying power when the power is turned off (in the case of a DC servo motor, when the power is turned off, the servo is no longer applied, It is not used because of problems such as its large size (free state) and its large size. Currently, suspension actuators include DC motors,
A structurally complex actuator consisting of gears and mechanical stops is used.

FIG. 2 shows the structure of a conventional eggplant pension actuator. In FIG. 2, 14 is a DC motor. A pinion gear 15 is attached to the rotating shaft of the DC motor 14, and is gear-coupled to the sector gear 1 [5]. The sector gear 16 has a bevel cut in about half of its circumference, and a protruding stopper 17 with a certain width is integrally formed on the opposite side. An arcuate hole is provided in a portion of the sector gear 16, and a stopper 18 is provided through the hole. The stopper 18 is the solenoid 1
It becomes possible to drive by the magnetic attraction force of 9.

A main shaft 20 is attached to the center of the sector gear 16, and is connected to a control rod 22 of a shock absorber 21 to transmit rotation.

The operation of the suspension actuator configured as above will be described below.

First, we will explain what role the eggplant pension actuator plays. The shock absorber 21 absorbs vibrations and shocks from the road surface, but recently it has been used to absorb vibrations and shocks from the road surface.
The damping of the shock absorber can be made soft or hard depending on the type of driving (high speed driving, rounding curves, etc.), or changing the damping constant of the shock absorber to 2 or 3 stages. is required. Therefore, the control rod 22 is set to ±60', O'', '-60'' and 2 (j't,
It is necessary to position it at the rt or 3 position. The suspension actuator performs this switching.

Now, when power is applied to the DC motor 14, the DC motor 14 rotates in one direction. The rotation is then transmitted to the sector gear 16 via the pinion gear 15, and the control rod 22 of the shock absorber 21 rotates. When the stopper 17 hits a wall surface provided on the case side, it cannot move any further and stops at that position. Next, when the polarity of the power source is reversed and power is applied to the DC motor 14, the DC motor 14 rotates in the opposite direction to the previous rotation, and the stopper 17 also moves in the opposite direction. It then hits a wall on the opposite side and stops in that position, unable to move any further. In this way, positioning is performed at two positions. Positioning at three positions can be performed by stopping at an intermediate position in addition to the two positions just described. In this method, the stopper 18 is attracted by the magnetic attraction force of one solenoid, and the stopper 18 is fitted into the groove provided in the sector gear 16, and the sector gear 16 is forced to illumination.
It has been stopped.

Problems to be Solved by the Invention However, the above-mentioned configuration has the problem of being structurally complex, resulting in a large shape, and having gears, stoppers, solenoids, etc., resulting in poor response. had. In view of the above-mentioned problems, the present invention is: (1) compact, (2) suitable for structural parts, (4) capable of direct drive without using gears, stoppers, etc., (4) fast response, and (4) stops when the power is turned off. : The purpose is to provide a positionable actuator with holding torque.

Means for Solving the Problems In order to solve the above problems, the present invention consists of a stator in which a piezoelectric material is bonded to an elastic material such as iron or stainless steel, and a rotor in which a wear-resistant lining material is bonded. A permanent magnet or a light reflection plate is attached to the side or top and bottom surfaces of the rotor of an ultrasonic motor, and the position of the permanent magnet or light reflection plate is detected by a magnetically sensitive element or a photosensitive element to determine the position of the rotor. I made it possible to do it.
).

Effect The effect of this technical means is as follows. That is, since the stator and rotor of the ultrasonic motor are in pressurized contact with a certain appropriate load, they have a large static holding torque (approximately twice the motor starting torque) even when the power is off. Therefore, magnetically sensitive elements such as Hall elements (
When the ultrasonic motor is turned off at the moment when the position of the permanent magnet (light reflection plate) attached to the rotor is detected by the photosensitive element), a large frictional force is generated between the lining material and the stator. , the rotor can be stopped F at 4 o'clock. In this way a positioning actuator is possible.

EXAMPLE Hereinafter, an example of the present invention will be explained using FIG. 7A1. 1 is an elastic body made of metal such as iron or stainless steel. A piezoelectric body 2 and a piezoelectric body 3 are firmly bonded to the bottom surface of the elastic body 1 with a resin adhesive. Further, a ring-shaped protrusion 1a is provided on the upper surface of the elastic body 1, and the structure is such that the amplitude of mechanical strain is expanded and output is effectively extracted. These constitute the stator 4. The piezoelectric bodies 2 and 3 are each alternately polarized to positive and negative polarities (n: even number).The piezoelectric bodies 2 and 3 are mechanically in phase with π/in electrical angle. The piezoelectric bodies 2 and 3 are connected with lead wires so that a voltage can be applied to them.

The stator 4 is fixed to a fixed base 5 with an adhesive.

A bearing 9 is provided at the center of the stator 4, into which the shaft 8a of the rotor 8 is fitted. On the other hand, a wear-resistant tIZ lining material 7 is adhered to the rotor 8, and the ring-shaped protrusion 12t of the stator 4 described above is bonded to the rotor 8.
come into contact with. It looks like this. Further, the tip of the shaft of the rotor 8 is threaded, and is tightened with a spring washer 10 and a nut 11 so that the lining material 7 and the ring-shaped protrusion 13 are brought into contact and pressurized with an appropriate load. It has become. A permanent magnet 12 is placed on the outer peripheral surface of the rotor 8.
It is attached in three places. A magnetically sensitive element 13 such as a pole element or a magnetoresistive element is attached to the substrate 6 at a position facing the above-mentioned permanent magnet 12 with an appropriate gap.

The operation of the ultrasonic motor provided with the positioning means configured as above will be explained.

Ultrasonic motors are driven at the resonant frequency of the system. Now, piezoelectric bodies 2 and 3 each have π/2
When two-phase AC voltages having different phases and the resonance frequencies are applied, the stator 4 generates progressive mechanical strain waves. Therefore, the rotor 8, which is in pressurized contact with the stator 4, contacts only at the peaks of the waves (n/2 points). ), it is sent at the peak velocity of the wave in the opposite direction to the direction of travel of the wave, causing it to rotate. When the permanent magnet 12 attached to the outer peripheral surface of the rotor 8 comes to a position facing the magnetically sensitive element 13, an electric pulse is generated. Therefore, if the rising edge of the electrical pulse is detected and the two-phase AC voltage applied to the piezoelectric bodies 2 and 3 is cut off in a circuit at that point, mechanical strain will no longer occur in the stator 4 and the lining material 7 The ring-shaped protrusion 1a is in contact with the entire surface,
A large frictional force can be generated and the rotor 8 can be stopped instantly. In addition, in Fig. 2, the permanent magnets 12 are attached to three positions, and positioning is performed at three positions, but by attaching the permanent magnets 12 at m positions, it is possible to perform positioning at m positions. It is.

As described above, according to this embodiment, the stator is made up of an elastic body 1 and piezoelectric bodies 2 and 3 for exciting the elastic body 1, and the stator is pressed into contact with a certain appropriate load. In the ultrasonic motor configured with the rotor 8
By attaching a permanent magnet 12 to the rotor 8 and providing a magnetically sensitive element 13 such as a Hall element or a magnetoresistive element,
It is possible to perform positioning.

It is also possible to attach a light reflecting plate to the rotor 8 instead of the permanent magnet 12 and position the rotor using a photosensitive element such as a photoreflector.

Effects of the Invention As described above, the present invention comprises a stator composed of an elastic body and a piezoelectric body for exciting the elastic body, and a rotor that is brought into pressure contact with the stator under a certain appropriate load. By providing a positioning means that detects and positions the rotational position of the rotor, the ultrasonic motor configured is small, has a simple structure, can be driven directly, has a fast response, and has a torque that keeps it stationary even when the power is turned off. A positioning actuator having a positioning actuator can be provided.

[Brief explanation of drawings]

FIGS. 1(a) and (b) are a vertical cross-sectional view and a -E view of an ultrasonic motor equipped with a positioning means according to an embodiment of the present invention, and FIGS. 2(a) and (b) are views of a conventional suspension. They are a structural diagram and a vertical cross-sectional view of the actuator. 1... Elastic body, 2, 3... Piezoelectric body, 4
... Stator, 7 ... Lining, 8
......Rotor, 12...Hoss magnet, 13
...Magnetic sensing element. Name of agent: Patent attorney Toshio Nakao 1 person Figure 2/-1-G single L≦Setney diagonal 15 Mi2, . 3-; Piezoelectric body 4- Stay/7- Lining

Claims (3)

[Claims] (1) A stator composed of an elastic body and a piezoelectric body for exciting the elastic body, a rotor that is pressed into contact with the stator under a certain appropriate load, and detecting the rotational position of the rotor, An ultrasonic motor equipped with a positioning means for positioning. (2) The positioning means is constituted by a permanent magnet attached to the outer periphery of the rotor or the upper and lower surfaces near the outer periphery, and a magnetically sensitive element provided opposite to the permanent magnet. ultrasonic motor. (3) The positioning means is constituted by a light reflecting plate attached to the outer periphery of the rotor or the upper and lower surfaces near the outer periphery, and a photosensitive element provided opposite to the light reflecting plate. ultrasonic motor.