JPH03145980A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To realize highly efficient operation by arranging a sliding member having a specified low heat conductivity on the first elastic body side between the first and second elastic bodies. CONSTITUTION:Upon application of an AC electric signal onto a linear ultrasonic motor 31, an approximately oval vibration is induced at a driving section 32 and a ultrasonic vibrator 11 is subjected to a driving force caused by the frictional force with respect to a rail 34 and moves in the direction of an arrow B. The driving section 32 is composed of such material as having heat conductivity under normal temperature not higher than 1X10<-3>cal/ deg.C/cm.cm<2>.s, e.g. a phenol resin. Since the heat produced due to mechanical loss of the ultrasonic motor 31 does not transmit to the first elastic body 21 but transmits to the second elastic body 34, highly efficient operation can be sustained with no thermal influence on the first elastic body 21 and exciting source therefor.

Description

[Detailed description of the invention] 1. Industrial application field] The present invention relates to an ultrasonic motor.

[Prior Art J Conventionally, ultrasonic motors are broadly classified into traveling wave 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 vibration, and the frictional force between each mass point that moves approximately elliptically and the movable element causes the movable element to move. This is what drives the child. As an example, FIG. 3 shows a conventional example reported in the specification and drawings attached to Japanese Patent Application No. 1-46866.

In the linear ultrasonic motor 1, the ultrasonic vibrator 3 is fixed to a yoke 2, and a drive W is attached to one end of the ultrasonic vibrator 3.
14 is formed. A movable element 5 is pressed onto the drive section 4 by a rubber roller 6, and the movable element 5 is supported by linear bearings 7a and 7b fixed to the yoke 2.

In the linear ultrasonic motor 1 configured as described above, when the ultrasonic vibrator 3 is excited, the movable element 5 receives a driving force due to approximately elliptical vibration and moves in the direction of arrow A in the figure. This driving force is This is generated due to the frictional force between the drive section 4 and the movable element 5. In the above-mentioned ultrasonic motor, the ultrasonic vibrator 3 and movable element 5 are generally made of metal such as aluminum, copper, or iron in order to increase rigidity and energy density.

[Problem to be Solved by the Invention 1] However, in the above-mentioned ultrasonic motor, most of the drive loss occurs on the sliding surface between the ultrasonic vibrator and the movable element! It is occupied by 90 precepts, and this lost energy becomes heat. As a result, the electro-mechanical transducer, which is the excitation source of the ultrasonic transducer and is made of a piezoelectric element, is heated, its electro-mechanical conversion coefficient deteriorates, and the resonant frequency of the ultrasonic transducer itself changes. However, there was a problem in that the driving efficiency of the motor deteriorated significantly.

The present invention was made to solve the above-mentioned problems, and by preventing the heat generated by the Pa machine from being transmitted to the ultrasonic transducer, it is possible to operate stably and with high efficiency over a long period of time. The purpose of this invention is to provide an ultrasonic motor with small variations in drive characteristics.

[Means for Solving the Problems] In order to achieve this object distantly, the ultrasonic motor of the present invention includes a first elastic body that performs ultrasonic vibration, and a vibration energy of the first elastic body that is used as a driving source. In an ultrasonic motor that is provided with a second elastic body crimped to a first elastic body and performs relative motion, heat conduction is conducted between the first elastic body and the second elastic body on the side of the first elastic body at approximately room temperature. The degree is 1×10.

Furthermore, plastic is used for the sliding member.

[Function] In the m-sonic motor of the present invention having the above-described Vt angle, on the first elastic body side between the first elastic body and the second Maya L body,
Since a sliding member with low thermal conductivity is provided, heat generated due to mechanical loss of the m-sonic motor is not transmitted to the first elastic body, but is transmitted to the movable element and radiated, so that the first elastic body and High efficiency operation can be maintained without affecting the excitation source due to heat.

[Example] Hereinafter, an example embodying the present invention will be described with reference to FIGS. 1 and 2.

In this embodiment, a sliding member is interposed between the ultrasonic transducer and the movable element, and the ultrasonic transducer and the movable element are crimped together.

As the ultrasonic transducer, for example, Japanese Patent Application No. 1-4686
An ultrasonic transducer including a mechanical resonator as disclosed in the specification and drawings attached to application No. 6 is used.

An example of the configuration will be described below with reference to FIG.

The ultrasonic vibration T-11 is caused by an elastic body 2 having a rectangular flat plate shape.
A first piezoelectric body 22 for exciting bending vibration in the elastic body 21 is attached to the upper surface of the elastic body 1 .

A WS2 piezoelectric body 23a for exciting longitudinal vibration in the elastic body 21 is provided on a side surface perpendicular to the mounting surface of the elastic body 21.
and 23b are installed.

The longitudinal center of the elastic body 21 is fixed by fixing poles 24a and 24b for fixing the elastic body 21. The other ends of the fixed poles 24a and 24b are
It is fixed to bases 25a and 25b.

An electrode 26 is provided on the upper surface of the first piezoelectric body 22 . Further, electrodes 27a and 27b are installed on the upper surfaces of the second piezoelectric bodies 23a and 23b. The elastic body 21 itself also serves as a ground electrode, and is grounded to the bases 25a and 25b via the fixed poles 24a and 24b.

Furthermore, the elastic body 21 bends in a secondary mode at both free ends at a predetermined frequency in the thickness direction, and longitudinally vibrates in a primary mode at both free ends in the length direction at the same frequency f. The shape and dimensions have been adjusted.

Generally, the resonant frequency of longitudinal vibration propagating in an elastic body depends on the length of the elastic body. Further, the resonance frequency of bending vibration in the thickness direction of the elastic body depends on the length and thickness. Therefore, since it is easy to design the elastic body 21 as described above, the details thereof will be omitted.

The operation of the ultrasonic transducer 11 configured as above will be explained below.

First, when an AC voltage of frequency f is applied to the first piezoelectric body 22 to cause it to vibrate, the elastic body 21 bends and vibrates! P)s Resonance occurs in the secondary mode and a standing wave is excited.

Next, apply an AC voltage of frequency r to the second piezoelectric bodies 23a and 23b and shake them! When OJ is applied, the elastic body 21 resonates in the first-order longitudinal mode, and a standing wave is excited. In other words, the fixed positions of the fixed poles 24a and 24I are the nodes of each standing wave.

At this time, by adjusting the amplitude and phase of the voltages applied to the first piezoelectric body 22 and the second piezoelectric bodies 23a and 23b, it is possible to generate approximately elliptical vibration of an arbitrary shape in the elastic body 21. .

In the above example, longitudinal vibration 11!11th mode and bending vibration!
! b. An ultrasonic transducer that excites a secondary mode and synthesizes it to generate approximately elliptical vibration has been described, but is not limited to this, and can be used to generate vibrations such as longitudinal vibration, bending vibration, shear vibration, h-torsion vibration, etc. , it is possible to use a combination of various vibration modes, and higher-order modes may also be used.

Next, a description will be given of a linear ultrasonic motor Wlt that suitably utilizes the above-mentioned ultrasonic transducer 11 based on FIG.

In FIG. 1, each member with the same reference numeral as in FIG. 1 means the same as each component described in detail above.

The linear ultrasonic motor 31 has a drive JJ section 32 formed at the end that provides the maximum amplitude of the ultrasonic vibrator 11.
v! is crimped to the rail 34, which is the second elastic body, by the support member 33. He is holding a sword.

A crimping mechanism for applying the crimping force is disposed between the rail 34 and the support member 33, and is mounted on the roller bearing 3.
5 supported by the first id 3G and the coil spring 3
7 and spring guide 38, from 3 spring pressers v! being intimidated. This is done by rotating a spring retainer 39 along a screw groove attached to the spring guide 38, changing the length of the coil spring 37, and adjusting the pressing force.

On the other hand, the linear ultrasonic motor 3 is attached to the support member 33.
A second guide 40 is fixed with bolts 41 to prevent sideways displacement of the drive unit 1 . The rail is configured such that the rail 34 is held by roller bearings 42.

Furthermore, the linear ultrasonic motor is provided with a first support member 43 for preventing yawing and a second support member 44 for preventing rolling.

When an AC electric signal is applied to the linear ultrasonic motor 31 configured as described above, approximately elliptical vibration is generated in the drive section 32, and the driving force due to the frictional force with the rail 34 is transferred to the ultrasonic vibrator 11. is received and moves in the direction of arrow B in the figure.

Here, the drive section 32 is made of a material that does not stand at about room temperature, for example, phenol resin, and has a length l=I G (n
++++), width w = 3 (am), height h = 5 [m+m:
]. Thermal conductivity here refers to the amount of heat [CaI! ] and the temperature gradient in that direction ("C/帥").For example, in general, the material of the rail 34 for this purpose is metal such as the above-mentioned iron and iron alloy, Possible examples include Ceramifuchus.

In the above configuration, the linear ultrasonic motor 3
When the ultrasonic transducer 11 was driven, the temperature of the ultrasonic transducer 11 hardly increased, and heat was radiated through the rail 34.

As a result of studying the above-mentioned implementation results, it has been found that the operation of the ultrasonic motor can be stabilized by forming the sliding member using a thermally conductive material. Examples of materials having the above thermal resistance include not only 7-el resin, but also thermosetting a (Ill't) such as area cloth, epoxy resin, polyimide, etc. Most plastic materials can be used for plasticity Q (FIR'''I?), and can be used depending on the purpose of durability, responsiveness, etc.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, such as nails, etc., and it goes without saying that the present invention can be implemented in various forms without departing from the gist of the present invention. For example, as an electromechanical transducer, M
Any device capable of converting mechanical vibration into electrical energy, such as a strain element or a magnetostrictor T, may be used.

In the above embodiment, an ultrasonic vibrator that excites standing wave vibrations is used as the driving source, but the invention is not limited to this, and the same effect can be obtained by using an ultrasonic vibrator that excites traveling waves. is obtained.

Further, in the above embodiments, the ultrasonic transducer is shaped like a flat plate, but the shape is not limited to this, and various shapes such as a rectangular shape, a rod shape, a cylindrical shape, an annular shape, a disk shape, etc. The shape can be considered.

[Effects of the Invention] As is clear from the detailed description above, according to the present invention, it is possible to obtain an ultrasonic motor that is capable of stable high-speed operation over a long period of time and has small variations in drive characteristics.

[Brief explanation of the drawing]

Figures 151 to 2 show embodiments embodying the present invention, and Figure tj41 is! FIG. 2 shows an embodiment of the ultrasonic transducer, and FIG. 2 shows the configuration of a linear ultrasonic motor that suitably utilizes the ultrasonic transducer. Moreover, FIG. 13 is a diagram showing an example of the configuration of a conventional ultrasonic motor. 21 is a first external body, 34 is a second elastic body, and 32 is a sliding member.

Claims (1)

[Claims] 1. A first elastic body (21) that performs ultrasonic vibration, and a second elastic body (34) that is crimped to the elastic body (21) using the vibration energy of the elastic body as a driving source. In the ultrasonic motor that performs relative motion, the first elastic body side between the first elastic body (21) and the second elastic body (34) has a thermal conductivity of 1×10 at approximately room temperature.
^-^3 Sliding members below [cal/℃/cm・cm^2・s] (
32). 2. The ultrasonic motor according to claim 1, wherein the sliding member (32) is made of plastic.