JPH04156281A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To easily maintain and manage an ultrasonic motor by constituting the smaller one of the sliding surfaces of the first and second elastic bodies of a material having lower hardness than that of the material constituting the larger one and, at the same time, by installing the softer material in an exchangeable state. CONSTITUTION:This ultrasonic motor 35 is linearly driven against rails 34 laid in a facing state by means of a ultrasonic vibrator 11 which works as a needle. As a result, the area of the sliding section of a slider 34 can be made remarkably smaller against the sliding areas of the rails 34 which become larger in correspondence to the movable distance of the slider 32. Accordingly, a resin, such as nylon 6, etc., is used as the sliding material of the sliding section of the slider 32 and a ceramic material is used as the sliding material of the sliding sections of the rails 34. The hardness of the ceramic material is about ten times higher than that of the resin and the resin sliding material 40 used for the slider 32 is one-sidedly worn out. Therefore, when the worn-out resin is periodically exchanged, the service life of this ultrasonic motor can be prolonged.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an ultrasonic motor using ultrasonic vibration energy as a driving source, and more particularly to a sliding part structure thereof.

[Prior Art] Conventionally, an ultrasonic motor performs relative motion by pressing a movable element onto an ultrasonic vibrator and generating a thrust force using frictional force caused by the pressing force. A conventional example thereof is shown in FIG.

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

In the linear ultrasonic motor 1 configured as described above,
When the ultrasonic transducer 3 is excited, the movable element 5 receives a driving force due to the substantially elliptical vibration of the ultrasonic transducer 3, and moves in the direction of arrow A in the figure. This driving force is generated by the frictional force between the drive section 4 and the movable element 5.

Some of these ultrasonic motors have improved wear resistance by forming their sliding surfaces with a high hardness material such as ceramic in order to stabilize the operation and extend the service life. − [Problem to be solved by the invention] However, it is impossible to completely eliminate wear;
Even if a wear-resistant material such as ceramic is used for the entire sliding surface as in the above-mentioned ultrasonic motor, there is a problem in that once the sliding surface wears out, the life of the ultrasonic motor will come to an end.

Another problem is that ceramics, which are used as wear-resistant materials, are currently very expensive.

The present invention has been made to solve the above-mentioned problems, and aims to provide an ultrasonic motor that can be easily maintained and managed and can be used for a long time at low cost by improving the sliding part structure. The purpose is

[Means for solving the problem] In order to achieve this object, the ultrasonic motor of the present invention includes a first elastic body that performs ultrasonic vibration, and a second elastic body that is crimped to the first elastic body. In an ultrasonic motor, the second elastic body is driven by the vibration energy of the first elastic body to perform relative motion, the sliding surface of the first elastic body and the second elastic body, The side with a smaller sliding area is made of a material with lower hardness than the side with a larger sliding area, and the lower hardness material is installed so that it can be replaced.

Further, in the ultrasonic motor, it is preferable that the sliding surfaces of the first elastic body and the second elastic body are made of materials that differ by at least 10 times in terms of Vickers hardness.

Furthermore, as the material of the sliding surface, it is desirable to use ceramic as a high hardness material and resin as a low hardness material.

[Function] The ultrasonic motor of the present invention having the above configuration uses two types of sliding materials with different hardness, so the one with lower hardness wears more than the one with higher hardness. Almost no wear. Since a low-hardness material is used for the smaller sliding area, the low-hardness material may wear out, but with the above configuration, it can be easily replaced. Therefore, when the low hardness material is worn out, stable operation can be achieved over a long period of time by replacing the low hardness material.

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

The ultrasonic vibrator used in the ultrasonic motor of this example is:
For example, a device including a mechanical resonator as proposed in the specification and drawings attached to Japanese Patent Application No. 1-46866 may be used. An example of the configuration will be described below with reference to FIG.

The ultrasonic transducer 11 includes an elastic body 21 having a rectangular prism 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 21 .

Second piezoelectric bodies 23a and 23b for exciting longitudinal vibration in the elastic body 21 are attached to the side surfaces of the elastic body 21 that are substantially orthogonal to the mounting surface.

The longitudinal center of the elastic body 21 is fixed by fixing bolts 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.

Electrodes 27a and 27b are provided on the upper surface of the first piezoelectric body 22.
Or installed. The elastic body 21 itself also serves as a ground electrode, and is grounded to the bases 25a and 25b via the fixing bolts 24a and 24b.

Furthermore, the elastic body 21 has a predetermined frequency f in its thickness direction.
The shape and dimensions are adjusted so that the secondary moats at both free ends vibrate bendingly at the same frequency, and the primary moats at both free ends vibrate longitudinally in the length direction at the same frequency.

Generally, the resonant frequency of longitudinal vibration propagating in an elastic body is
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.

Further, amplifiers 28a and 28b are connected to the electrode 26 of the first piezoelectric body 22 and the electrodes 27a and 27b of the second piezoelectric bodies 23a and 23b. A power source 30 is connected.

The operation of the ultrasonic transducer 11 configured as above will be explained below. First, when an alternating current voltage of frequency f is applied to the first piezoelectric body 22 to cause it to vibrate, the elastic body 21 resonates in a secondary mode of bending vibration, and a standing wave is excited. Next, when an alternating current voltage of frequency f is applied to the second piezoelectric bodies 23a and 23b to cause them to vibrate, the elastic body 21 vibrates in the first mode of longitudinal vibration, and a standing wave is excited. In other words, the fixing bolt 2
The positions fixed at 4 and 24 are nodes of each standing wave.

At this time, the first piezoelectric body 22 and the second piezoelectric bodies 23 and 23
By adjusting the amplitude and phase of the voltage applied to the elastic body 21, it is possible to generate approximately elliptical vibration of any shape in the elastic body 21.

Next, the configuration of the ultrasonic transducer of this embodiment using the above ultrasonic transducer will be explained with reference to FIGS. 4 and 5.

In FIG. 4, driver elements 32 are formed at both ends of the ultrasonic vibrator 11 that provide the maximum amplitude, and are in contact with a rail 34, which is a second elastic body, and drive an ultrasonic motor 35. It consists of

FIG. 5 shows piezoelectric bodies 22 and 23a of the ultrasonic transducer 11,
23b is a diagram showing a voltage waveform of a human power signal applied to the terminal 23b. When an AC electric signal is applied to the ultrasonic vibrator 11 to excite it, the ultrasonic vibrator 11 generates a driving force by repeating vertical and bending vibrations as shown in FIGS. 4(a) to (d). Occur. That is, in FIG. 4(a), the phases of both vibrations are adjusted so that the left end of the drive section 32 comes into contact with the rail 34 during expansion and contraction of the longitudinal vibration. Next, as the shape of the ultrasonic transducer 11 changes over time as shown in FIGS. 4(a), 4(b), and 4(c), the right end of the drive unit 32 comes into contact with the rail 34 when the longitudinal vibration contracts. When the driven rail 32 and the rail 34 come into contact with each other, a driving force resulting from their frictional force is received, and a thrust force is generated in a predetermined direction. The water always points in the same direction, as indicated by arrows A and B in the figure. The speed of the ultrasonic transducer 11 can be adjusted by the voltage and phase of the input signal, and the driving direction can be arbitrarily changed depending on the phase.

Next, the structure of the sliding part of the ultrasonic motor of this embodiment will be explained with reference to FIGS. 1 and 6.

In the above-mentioned ultrasonic motor 35, the ultrasonic vibrator 11 is used as a movable element, and is driven linearly with respect to the rail 34 arranged oppositely. Therefore, the sliding area of the rail 34 increases according to the movable distance, and the ultrasonic transducer 11
The area of the sliding portion of the drive element 32 provided in the drive element 32 can be made much smaller.

Therefore, resin such as nylon-6 is used as the sliding material 40 for the sliding portion of the driver 32, and ceramic is used as the sliding material 50 for the sliding portion of the rail. As shown in FIG. 6, the hardness of these sliding materials 40 and 50 is about 10 times different.

Therefore, when the ultrasonic motor 35 is driven, the resin sliding member 40 attached to the driver 32 is unilaterally worn out. Therefore, by periodically replacing the worn resin, the life of the ultrasonic motor can be extended. On the other hand, the ceramic sliding material 5o, which has a large sliding area and is expensive, can maintain good mechanical accuracy over a long period of time.

In the above-mentioned embodiments, resin is used as an example of a low hardness material, but the invention is not limited to this; for example, for ceramics, carbon steel, which has a relatively low hardness, is used as a low hardness material. You can also do that.

Regarding the method of attaching and detaching the sliding material used in the driver 32, the first
This will be explained using figures.

A driver 32 provided on the elastic body 21 of the ultrasonic transducer 11
In this step, the surfaces of the two drive elements 32 are polished to form a polished surface 4.
Machining is performed so that 0a and 40b are located within the same plane. If the flatness at this time is made sufficiently smaller than the vibration amplitude of the ultrasonic vibrator, good operation of the ultrasonic motor can be achieved. Next, adhesive 40 is applied to polished surfaces 40a and 40b.

Then, the sliding members 42-a and 42b are installed so that the machining accuracy such as parallelism and flatness is equal to the flatness of the polished surfaces 40a and 40b described above. Therefore, when the ultrasonic motor 35 is driven for a long time and the driving characteristics deteriorate, simply by replacing the sliding members 42a and 42b, it is possible to always maintain good machining accuracy.

The sliding material attached to the ultrasonic transducer 11 can be peeled off by using a solvent such as acetone or by heating it to about 50° C. or higher, for example, when instant adhesive is used as the adhesive. , just apply impact force.

Next, a second embodiment of the method for attaching and detaching the sliding member will be described with reference to FIG.

The drive shaft 32 of the elastic body 21 is provided with a groove, and has a structure in which a sliding member 42 having a protrusion corresponding to the groove shape is held therebetween. Therefore, unlike the first embodiment, there is no need to use an adhesive, and the sliding member can be attached and detached more easily.

Although a piezoelectric material was used as the excitation source for the elastic material in this embodiment, it is not limited thereto, and other elements capable of converting electrical energy into mechanical energy, such as an electrostrictive element or a magnetostrictive element, may also be used. good. Moreover, its shape is not limited to a flat plate, and various shapes can be considered. Furthermore, the shape of the first elastic body is not limited to a prismatic shape, but a flat shape,
Various shapes can be considered, such as a disk shape, an annular shape, and a cylindrical shape.

Further, in this embodiment, the ultrasonic motor is explained using a standing wave type ultrasonic motor as an example, but the ultrasonic motor is not limited to this. The same effect can be obtained even when applied to various motors such as ultrasonic motors, rotary type, linear type, etc.

In the above embodiment, an ultrasonic vibrator that excites the first-order mode of longitudinal vibration and the second-order mode of bending vibration and generates approximately elliptical motion vibration by combining them is described, but the present invention is not limited to this. It may be a combination of various vibrations such as vibration, bending vibration, shear vibration, and torsional vibration, and higher-order modes may also be used.

In addition, various modifications can be made without departing from the spirit of the present invention.

[Effects of the Invention] As is clear from the detailed description above, according to the present invention, an ultrasonic motor can be used for a long period of time by replacing only the worn parts. Therefore, maintenance and management are facilitated.
It is possible to create an ultrasonic motor that can be used for a long time at low cost.

[Brief explanation of the drawing]

1 to 6 show embodiments embodying the present invention, FIG. 1 is a diagram showing a first embodiment of a method for attaching a sliding material, and FIG. 2 is a diagram showing a first embodiment of a method for attaching a sliding material. FIG. 3 is an explanatory diagram of the ultrasonic transducer used in this embodiment, FIG. 4 is an explanatory diagram of the operation of the ultrasonic motor, and FIG.
The figure shows the voltage waveform of the input signal applied to the piezoelectric body of the ultrasonic transducer, and FIG. 6 shows the hardness of the sliding material used in this example. Further, FIG. 7 is a diagram showing a conventional example of an ultrasonic motor. In the figure, 21 is an elastic body, 34 is a rail, 40 is a sliding material, and 5
0 is a sliding material.

Claims (1)

[Claims] 1. The ultrasonic device includes a first elastic body that performs ultrasonic vibration, and a second elastic body that is crimped to the first elastic body, and the second elastic body is driven by the vibration energy of the first elastic body to perform relative motion. In the sonic motor, the sliding surfaces of the first elastic body and the second elastic body are made of a material with a lower hardness than the one with a larger sliding area, and the lower hardness material is replaced. An ultrasonic motor characterized by being able to be installed.