JPH02266880A - Ultrasonic actuator - Google Patents

Abstract

PURPOSE:To prevent overheating by providing a temperature regulating unit consisting of a material of a configuration, changed according to temperature. CONSTITUTION:An ultrasonic actuator is constituted of a cantilever beam 1, aluminum washers 2, 5, piezoelectric vibrators 31, 32, terminal plates 41, 42 and a cap bolt 6. Temperature regulating units 201, 202, made of a shape memory alloy and showing a chevron shape at a normal temperature, are formed between the beam 1 and the washer 2. As a result, the cantilever beam 1 is deformed by the temperature rise of a pressing unit whereby contact between the cantilever beam 1 and the washers 2 is eliminated and the ultrasonic actuator may be stopped.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an improvement in an ultrasonic actuator that drives a mover by vibration of an elastic body. It is roughly divided into type and standing wave type.

The basic operating principle of these ultrasonic motors is that a movable element is brought into contact with a predetermined pressure against an ultrasonic vibrator that excites approximately elliptical vibrations, and the friction force between each mass point moving approximately elliptically and the movable element is used to move the movable element. It is a device that drives the
It has been reported in the No. Its concrete structure is shown in FIGS. 4 and 5.

In the figure, 31 and 32 are excitation piezoelectric vibrators, which are defined by sandwiching a terminal plate 41 between positive electrodes.

The negative electrode sides of the piezoelectric vibrators 31 and 32 are connected to terminals @
42, stack the aluminum washers 2 and 5 on the outside, and then pass the cap bolt 6 through the bolt hole provided in the aluminum washer 5, and tighten the tip of the bolt 6 into the screw hole of the cantilever beam 1. , and the piezoelectric vibrator 3.
Lead wires 71 and 7□ are connected to and 32. Piezoelectric vibrators 31 and 3. When a sinusoidal voltage is applied to the oscillators 31 and 3□, vibration occurs in the thickness direction, and as a result, the washer 2
The longitudinal vibration is transmitted to the upper V5, and the base portion 12 of the cantilever beam 1 is vibrated. Pass the bolt 6 through the center screw hole on this base part 1□.
Since the beam is tightened, the longitudinal vibration transmitted to the base part 12 becomes a bending vibration of the base part 12, and bending vibration occurs in the beam. Beam 1
is the base part 1. Groove 1. Since it stands obliquely to the pedestal 12, if the platform 12 is concave, the free end surface of the beam 1 will receive a force directed toward the inside of the concave, that is, the arrow 10 shown in FIG. and 1
0. receive force in the direction. As a result, torsional vibration occurs in the beam 1, but since the bolt 6 supporting the beam 1 expands and contracts due to the longitudinal vibration of the vibrator, the free end surface of the beam 1 undergoes an elliptical motion that is a combination of torsional vibration and longitudinal vibration. Moreover, the horizontal diameter of the ellipse is 1 beam
It is zero at the center, and increases as the distance from the center increases, reaching a maximum on both sides in the width direction, but when the direction away from the center is reversed, the elliptic motion rotates in the opposite direction as shown by arrows 10 and 10□ in FIG.

[Problems to be Solved by the Invention] However, as mentioned above, since the ultrasonic actuator uses frictional force as its driving source, most of the energy loss is converted to heat, and as a result, for example, the actuator overheats when overloaded. In addition, when a piezoelectric element is used as an excitation source, there is a problem in that the performance of the piezoelectric element is seriously deteriorated due to temperature rise.

[Purpose of the Invention] The present invention has been made to solve the above-mentioned problem α. An object of the present invention is to provide an ultrasonic motor that prevents overheating and avoids permanent deterioration of piezoelectric elements or contact surfaces by changing the shape of a temperature adjustment part at a certain set temperature and stopping the drive of the ultrasonic actuator. It is said that

[Means for Solving the Problems] In order to achieve this object, the ultrasonic actuator of the present invention includes an elastic body that performs ultrasonic vibration, and a drive source using the vibration energy of the elastic body, and an ultrasonic actuator that is crimped to the elastic body. In the ultrasonic actuator having a movable element, at least a part of the elastic body or the movable element is provided with a temperature adjusting part that acts so that the elastic body is no longer in contact with the movable element due to an increase in temperature of the crimping part. .

[Function] In the ultrasonic actuator of the present invention having the above configuration, the drive of the seven actuators is stopped at a set temperature by a temperature adjusting section whose shape changes depending on the temperature, which is provided in at least a part of the elastic body or the movable element. Therefore, overheating of the actuator can be easily prevented.

[Example] Hereinafter, an example embodying the present invention will be described with reference to FIGS. 1 to 3.

FIG. 1 is a side view of the ultrasonic actuator of this embodiment, and FIG. 2 is a top view of this embodiment. Further, FIG. 39 shows an explanatory diagram of the operation of this embodiment. In this figure, each member given the same reference numeral as in FIGS. 4 and 5 means the same thing.

Between the lower surface of the cantilever beam 1 and the upper surface of the aluminum washer 2,
A portion of the cantilever beam 1 is formed with adjusting portions 20 and 202 which are made of a shape memory alloy and have a dogleg shape at room temperature.

The temperature adjusting sections 20 and 202 are adjusted in advance so that they have the above-mentioned dogleg shape at the set temperature T, and expand toward the bottom in the figure when the set temperature T is exceeded.

The operation of the ultrasonic 7-cut unit configured as described above will be explained below with reference to FIG. In the figure, the lower part of the vibrator is omitted.

When an AC electric signal is applied to drive the ultrasonic actuator in the state shown in FIG. 3(a), friction between the lower surface of the cantilever beam 1 and the upper surface of the aluminum washer 2 generates frictional heat. The frictional heat is transmitted through the cantilever beam 1 and the temperature adjusting section 20. and 202 is heated. The temperature il!
Orthopedic department 20. and when the temperature of 20° exceeds the set temperature T, the temperature 119 parts 20. and 202 extend toward the bottom in the figure, and the cantilever beam 1 is deformed, so the contact between the cantilever beam 1 and the aluminum washer 2 is lost, and the ultrasonic actuator stops.

Although the above embodiment has been described using a rotary ultrasonic motor as an example, the present invention is not limited to this, and can also be implemented with a seven-actuator such as a linear drive ultrasonic motor.

Further, in the embodiment, an example in which the shape of the temperature adjustment section is a dogleg shape has been described, but various modifications such as a coil spring shape are possible without departing from the spirit of the present invention.

[Effects of the Invention 1] As is clear from the detailed description above, according to the present invention, a temperature adjustment section made of a material and shape whose shape changes depending on the temperature is provided, and the temperature of the ultrasonic actuator becomes equal to or higher than the set temperature. Since the ultrasonic actuator is configured to stop driving at times, it is possible to obtain an ultrasonic actuator that prevents overheating and avoids permanent deterioration of the piezoelectric element or the contact surface.

[Brief explanation of drawings]

1 to 3 show embodiments embodying the present invention, FIG. 1 is a side view of the ultrasonic actuator of the present invention, FIG. 2 is a top view thereof, and FIG. The figure is an explanatory diagram of its operation, and FIGS. 4 and 5 are diagrams showing a conventional example. 1...Cantilever beam, 2...Aluminum washer, 20+~
2...Temperature adjustment section.

Claims (2)

[Claims] 1. An ultrasonic actuator comprising an elastic body that performs ultrasonic vibration, and a movable element that uses the vibration energy of the elastic body as a driving source and is crimped to the elastic body, the crimping being applied to at least a part of the elastic body or the movable element. 1. The sonic actuator according to the present invention, further comprising a temperature adjusting section that acts to cause the elastic body to come out of contact with the movable element due to an increase in temperature of the sonic actuator. 2. The ultrasonic actuator according to claim 1, wherein the temperature adjustment section is formed of a shape memory alloy.