JPH03243175A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To operate an ultrasonic motor stably for a long period of time by a method wherein the spraying coat layer of chromia series ceramics compound is formed on one or both surfaces of the sliding surfaces of first and second elastic bodies. CONSTITUTION:AC voltage is impressed on first and second piezo-electric bodies 22, 23 and ultrasonic oscillation is effected by the first elastic body 21. The second elastic body or a rail 34, pressed against the first elastic body 21, is driven by the oscillating energy of said first elastic body 21. In this case, the spraying coat layer 61 of chromia series ceramics compound is formed on one or both of the sliding surfaces of the first elastic body 21 and the second elastic body 34. According to this method, an ultrasonic motor, prominent in thermal conductivity, hardly increasing in abrasion due to temperature rise, excellent in resistance to abrasion, capable of being increased in the accuracy of machining works since the porosity of the same can be reduced and capable of being increased in the output thereof, can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ultrasonic motor using ultrasonic vibration energy as a driving source.

[Prior Art] Conventionally, an ultrasonic motor performs relative motion by press-fitting a movable element to an ultrasonic vibrator and generating thrust by frictional force caused by the press-fit force. A conventional example 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.

In many of these ultrasonic motors, ceramic is attached to the sliding surface and used as a wear-resistant material in order to stabilize operation and extend life.

[Problem to be solved by the invention] However, while ultrasonic motors require high machining precision, as in the above-mentioned ultrasonic motors, ceramic materials such as alumina film are used, so Due to the high porosity, it was difficult to achieve machining accuracy on the micron order, and as a result, it was not possible to operate stably over a long period of time. Furthermore, even if ceramic is used as the wear-resistant material, there is a problem in that it is adhesively fixed at a location where shear core force is most likely to occur and is easily peeled off, and the adhesive is also likely to peel off due to an increase in temperature.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to obtain an ultrasonic motor that operates stably over a long period of time by improving the structure of the sliding part. Furthermore, since metal is used for the elastic body on which the sprayed layer is formed, the objective is to obtain an ultrasonic motor that has excellent thermal conductivity and exhibits less increase in wear due to temperature rise.

Furthermore, since chromia ceramic is used as the sliding material, it has excellent wear resistance, and by reducing the porosity, machining accuracy is increased, resulting in a high output ultrasonic motor. is its purpose.

[Means for Solving the Problems] 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. The ultrasonic motor drives the second elastic body by the vibration energy of the first elastic body to perform a relative motion, and a chromia is applied to one or both of the sliding surfaces of the first elastic body and the second elastic body. A sprayed layer of ceramic compound is formed.

Further, it is preferable that a metal material be used for the first elastic body or the second elastic body, and grooves may be formed in advance at the sprayed portion of the chromia ceramic compound.

Further, as the chromia ceramic, Cr2O3-S
An i 02-T i 02 compound may be used.

[Function] In the ultrasonic motor of the present invention having the above configuration, grooves are formed in the elastic body of the ultrasonic motor formed of a metal material,
Cr203-8 i 02 as chromia ceramic
- Because it is thermally sprayed with T i 02 compound, it has excellent thermal conductivity, is less likely to increase wear due to temperature rise, has excellent wear resistance, and can reduce porosity, making it possible to increase machining accuracy. , it is possible to increase the output of ultrasonic motors.

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

The ultrasonic transducer used in the present invention can be used, for example, in Japanese Patent Application No. 1-46
An ultrasonic transducer including a mechanical resonator as proposed in the specification and drawings attached to the '866 application 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 2 is mounted on the upper surface of the elastic body 2.

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 fixing bolts 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.
has been 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 it bends in a secondary mode at both free ends, and longitudinally vibrates in a primary mode at both free ends in the longitudinal direction at the same frequency f.

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.

Furthermore, 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, the predetermined frequency f is applied to the first piezoelectric body 22.
When the elastic body 21 is vibrated by applying an alternating current voltage of , the elastic body 21 resonates in the secondary mode of bending vibration, and a standing wave is excited. Next, when the second piezoelectric bodies 23a and 23b are vibrated by applying an alternating current voltage having approximately the frequency f, the elastic body 21 vibrates in the first mode of longitudinal vibration, and a standing wave is excited. In other words,
The positions fixed by the fixing bolts 24 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.

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. Various vibrations such as vibration, bending vibration, shear vibration, and torsional vibration can be synthesized, and higher-order modes may also be used.

The operating principle of an ultrasonic motor that suitably utilizes the above-mentioned ultrasonic transducer will be explained with reference to FIGS. 2 and 3. In this figure, each member given the same reference numeral as in FIG. 1 indicates that it is the same as each component described in detail above.

In FIG. 2, 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. 3 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. 3(a) to 3(d). Occur. That is, in FIG. 3(a), the phase of the circular vibration is 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. 3(a), 3(b), and 3(c), the right end of the drive unit 32 comes into contact with the rail 34 when the longitudinal vibration contracts. When the drive shaft 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 direction is as shown by arrows A and B in the same figure.
always facing the same direction. The speed of the ultrasonic transducer 11 can be adjusted by the voltage and phase of the human power signal, and the driving direction can be arbitrarily changed depending on the phase.

Next, a specific example of the configuration of the linear ultrasonic motor 35 will be described with reference to FIGS. 4 and 5.

In FIG. 4, the ultrasonic transducer 11 has support members 40 formed at its nodes. The support member 40 is supported by a groove 42 provided in a yoke 41 so as to have a degree of freedom in the vertical direction. The yoke is fixed on a base 44 by two linear bearings 43a and 43b, and is movable in the direction of arrow A in FIG.

On the other hand, a plate spring 50.
A crimping mechanism is formed by a spring presser 51, a spring guide 52, and a holder 53.

These are the spring guides 52 supported by the holder 53.
By rotating the spring presser 51 along the screw groove formed in the plate spring 50, the height of the leaf spring 50 is adjusted and the pressing force is controlled.

Further, the rail 34 is installed on the base 44 so as to come into contact with the driver 32 of the ultrasonic transducer 11.

With the above configuration, in the above-mentioned ultrasonic motor, there is no structural restriction on the stator side rail 34, and a track with any curvature can be configured by simply providing a simple support mechanism. can do.

In addition, when the ultrasonic motor is not driven, it is held by frictional force, and this force is usually a large value of 2 to 5 times or more than the driving force of the ultrasonic motor. An angular slope can also be constructed.

Furthermore, ultrasonic motors generally have superior stopping precision and responsiveness compared to electromagnetic motors.

Here, taking the rail 34, which is the second elastic body, as an example,
A method for forming a ceramic sprayed layer will be explained.

(1) Formation of thermal spray grooves...on the sliding side of the rectangular flat rail 34, as shown in FIGS. 6(a) and (b),
=o, a groove 60 of approximately 1 to 0.5 [mm] is formed by cutting. In order to uniformly form a sprayed layer, the corners of the grooves 60 are preferably arcuate, and the cut angle θ of the grooves 60 is preferably inclined at about 45 degrees.

(2) Blasting treatment: Alumina grid or steel grid with a roughness of #20 to #50 is sprayed onto the grooves 60 by air blasting.

(3) Thermal spraying... Cr2- as a chromia ceramic
8 i 02-T i 02 compound is sprayed into the grooves 60 . (FIG. 6(C)) (4) Surface polishing: The sprayed layer 61 is finished by polishing to a surface roughness of about 1 μm to 10 μm using a diamond grindstone. #200 due to the roughness of the whetstone. Machining time can be shortened by selecting about three types, #800° and #2400, and processing them in stages.

By forming the sprayed layer 6e in the groove 60 as described above, the mechanical strength of the sprayed layer 61 can be improved. (Fig. 6(d) and (e)) Here, the material of the elastic body on which the sprayed layer is formed is aluminum, steel,
If a metal material such as brass is used, the heat generated on the sliding surface can be effectively dissipated. As a result, it is possible to obtain the effect that there is little increase in wear due to temperature rise.

Next, the surface roughness of the ceramic sprayed layer will be explained below with reference to FIGS. 7 and 8.

FIGS. 7(a) and 7(b) are enlarged photographs of the structures of the sprayed surfaces of alumina and chromia at the same magnification. Moreover, FIGS. 8(a) and 8(b) show the actual measurement results of the surface roughness of alumina and chromia obtained by the same polishing method. From Figure 7, when comparing the porosity, alumina has a porosity of 5 to 7%, while chromia has a porosity of 2 to 3%.
%], which is less than l/2. As a result, the 8th
As shown in the figure, the surface roughness of alumina is 1.1 [μ
m] is the limit, whereas the surface roughness of Chromia is 0.
38 [μm] has been achieved. That is, by using chromia, the porosity can be reduced, so machining accuracy can be increased, and as a result, a large output of the ultrasonic motor can be realized.

Next, the alumina and C as a chromia ceramic
The results of a wear resistance test using the r203-8 i 02-T i 02 compound will be explained with reference to FIG. 9. Here, a ring-plate method was used as an evaluation index of wear resistance. This involves pressing a ceramic ring against a phenolic resin plate in which glass fibers are dispersed at a predetermined pressing force P, and moving the ring at a desired speed V.
It was determined from the wear volume when rotating at That is, the specific wear iW was defined as the wear volume [mm 3 ] at a predetermined pressing force P=1 [kgf] and a predetermined sliding distance [mm].

As a result, the specific wear amount W [mm3/kg f・m
FIG. 9 shows the relationship between the speed v [m/s] and the speed v [m/s]. The results show that chromia causes less wear on bephenol resin plates than alumina. In addition, a diamond plate (roughness #200) was used as the plate, pressure force P = 3 [kgf], and predetermined speed v = 0.1.
When a wear resistance test was conducted at [m/s], the specific wear amount was W = 8. 5 X 10-5 [m
m3/kg f - mm], W = 25 in alumina
．． OX 10-5 [mm3/kgf-mm] and
Chromia has much less wear.

Furthermore, the ultrasonic motor using this chromia-based ceramic as a sliding material had much better wear resistance than conventional ultrasonic motors using alumina-based ceramic, and operated stably over a long period of time.

In the above embodiment, the sliding material is arranged on the rail 34, but the sliding material is not limited thereto.
It may be formed by thermal spraying on one or both of the sliding surfaces of the elastic body.

In this example, a piezoelectric material was used as the excitation source for the elastic material, but the invention is not limited to this. Other elements capable of converting electrical energy into mechanical energy, such as an electrostrictive element, a magnetostrictive element, etc., may also be used. Good too. Moreover, its shape is not limited to a flat plate, but 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 are possible, 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.

Further, in this embodiment, the crimping mechanism has been described using a leaf spring as an example, but the present invention is not limited to this, and various springs such as coil springs, application of magnetic force, etc. can be considered.

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, by improving the sliding part structure, it is possible to realize an ultrasonic motor that operates stably over a long period of time. Further, since metal is used for the elastic body on which the sprayed layer is formed, it is possible to realize an ultrasonic motor that has excellent thermal conductivity and has less increase in wear due to temperature rise. Furthermore, since chromia-based ceramic is used as the sliding material, it has excellent wear resistance, and the porosity can be reduced, making it possible to increase machining accuracy, resulting in a high output ultrasonic motor. can.

[Brief explanation of drawings]

1 to 9 show embodiments embodying the present invention. FIG. 1 is an explanatory diagram of an ultrasonic transducer used in this embodiment, and FIG. 2 is an illustration of an ultrasonic motor. FIG. 3 is a diagram showing a voltage waveform of a human power signal applied to the piezoelectric body of the ultrasonic transducer, and FIG. 4 is a diagram showing a top view of the ultrasonic conveying device of the present invention. FIG. 5 is a diagram showing a CC cross section in the above diagram; FIG. 6 is a diagram illustrating a method of forming a sprayed layer; Figures (a) and (b) are enlarged photographs of the structures of the sprayed surfaces of alumina and chromia at the same magnification, and Figures (a) and (b) are photographs of the alumina and chromia sprayed surfaces obtained by the same polishing method. FIG. 9 is a diagram showing the relationship between the specific wear amount W [mm3/kgf - mm] and the speed v [m/s]. FIG. 10 is a diagram showing a conventional example of an ultrasonic motor. 21 First elastic body 34 Second elastic body 60 Groove 61 Sprayed layer

Claims (1)

[Scope of Claims] 1. A first elastic body that performs ultrasonic vibration, and a second elastic body crimped to the first elastic body, wherein the vibration energy of the first elastic body causes the second elastic body to vibrate. The ultrasonic motor is driven to perform relative motion, characterized in that a sprayed layer of a chromia-based ceramic compound is formed on one or both of the sliding surfaces of the first elastic body and the second elastic body. ultrasonic motor. 2. In the ultrasonic motor according to claim 1, a metal material is used for the first elastic body or the second elastic body, and grooves are previously formed in the sprayed area of the chromia ceramic compound. An ultrasonic motor characterized by: 3. In the ultrasonic motor according to claim 1 or 2, the chromia ceramic is Cr_2O_3-SiO_2.
- An ultrasonic motor characterized by using a TiO_2 compound.