JPH02119581A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To maintain high performance by using an extremely simple constitution by a method wherein a pin for transmitting friction torque, composed of stainless, etc., on an ultrasonic elliptical vibration generating surface in a connector, is projected from the ultrasonic elliptical vibration generating surface. CONSTITUTION:Pins 10 for transmitting friction are fixed to ultrasonic elliptical vibration generating surfaces (the nose surfaces of beams 4) 9 in a connector 5 having a resonator 4 and the beams 4 respectively, and the pins 10 consist of steel, stainless or ceramics having HRC 40 or above. The pins 10 are made up of pin head sections 21 and press-fitting shaft sections 22 having a diameter smaller than the pin head sections 21, and the press-fitting shaft sections 22 are press-fitted into holes 23 in the axial core direction shapedly provided to the nose surfaces 9 of each beam section, thus press-fitting and fastening the pins 10 to separate nose surface 9. The height of projection from each nose surface 9 is kept constant. Accordingly, the pins 10 have high hardness and abrasion resistance, thus stabilizing the conditions of revolution on a torque transmission surface.

Description

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

(Prior art) Recently, vibrations in the vertical direction (thickness direction) generated in a piezoelectric element are transmitted to a cantilever-like connector to generate elliptical mode vibrations on the end face of the connector. The rotor (rotor) is crimped against the connector end face due to the generated elliptical mode vibration.
An ultrasonic motor has been developed to drive the rotation.

In such an ultrasonic motor, the material of the connector, that is, the elliptical mode vibration generating section, is often made of aluminum, duralumin, or the like, which has good acoustic vibration characteristics. However, the joint surface of the connector made of such a material with the rotor, that is, the frictional torque transmission surface to the rotor, wears out during the contact torque transmission with the rotor, which deteriorates the performance and RF life of the ultrasonic motor. Since it has the drawback of deterioration, various proposals have been made to improve this drawback.

For example, methods include manufacturing the connector (elliptical vibration generating part) with ceramic, coating the connector with ceramic (Japanese Patent Laid-Open No. 109776/1983), and forming an oil film on the sliding surfaces of the rotor and connector. Method (Unexamined Japanese Patent Publication No. 63-36
60) and a method of providing an elastic thin film between the rotor and the connector (Japanese Unexamined Patent Publication No. 63-124785).

[Problem to be solved by the invention]

The above-mentioned conventional techniques are not satisfactory because they each have the following problems.

First, there is a technique of coating the connector with ceramic, but the current technique requires expensive equipment to perform such coating, resulting in extremely high costs. In addition, the technology to make the connector itself from ceramic is
From a cost standpoint, it is thought that the cost will be higher than that of the ceramic coating described above.

In addition, in the technology of forming an oil film on the sliding surfaces of the rotor and connector, it is extremely difficult to supply a constant oil film over a long period of time so that its function can be maintained, and to control the film thickness. Moreover, a lubricating device that satisfies these conditions is required, and in this case as well, the cost becomes extremely high.

In the technology in which an elastic thin film is provided between the rotor and the connector, the elastic thin film is significantly worn down during torque transmission due to frictional sliding between the connector and the rotor, so the wear resistance of the elastic thin film is extremely high. This is thought to have a significant impact on the lifespan of the sonic motor itself.

Furthermore, elastic thin films have a problem in wear resistance compared to metals. Furthermore, adhesion between a metal and an elastic thin film has a major problem in that it tends to peel off at the adhesion interface due to the difference in linear expansion coefficient between the two.

The present invention has been made in view of the problems of the prior art described above, and it is an object of the present invention to provide an ultrasonic motor with an extremely simple configuration, good performance, and long life at a low cost.

[Means to solve the problem]

In order to solve the above problems, an ultrasonic motor according to the present invention is configured such that a rotor is brought into pressure contact with a surface of a connector where ultrasonic elliptical vibration occurs, and the rotor is rotated using the elliptical vibration as a driving source. In the ultrasonic motor, a friction torque transmitting pin made of stainless steel, iron with an HRC of 40 or more, or ceramic is provided on the ultrasonic elliptic vibration generating surface of the connector, protruding from the ultrasonic elliptic vibration generating surface. It is composed.

In this case, the friction torque transmission pin is composed of a large-diameter head and a small-diameter shaft portion that is smaller in diameter than the head, and the ultrasonic elliptical vibration of the pin is caused by the stepped portion of the head and small-diameter shaft portion. It is desirable that the height of the protrusion from the generation surface is constant.

Further, a hole parallel to the vibration generation surface is provided near the ultrasonic elliptical vibration generation surface, and a friction torque transmission pin is inserted and fixed into the hole so that its upper surface protrudes from the vibration generation surface, The rotor and the pin may be configured to be in line contact.

[Function] In the above configuration, when elliptical vibration occurs on the elliptical vibration generating surface of the connector, the vibration rotates the rotor via the friction torque transmission pin. At this time, torque is transmitted to the rotor due to friction, but since the transmission pin has high hardness and wear resistance, the rotation conditions on the sliding surface (torque transmission surface) are stable, extending the life of the ultrasonic motor. be converted into moreover,
Linear contact between the pin and rotor reduces the contact area, stabilizes rotation, and eliminates noise.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

(First Embodiment) FIG. 1 is a front view showing the configuration of a first embodiment of an ultrasonic motor 1 according to the present invention, with a portion shown in cross section for convenience of explanation. 2 is an enlarged perspective view of the main part of FIG. 1, and FIG. 3 is an exploded perspective view of the main part of FIG.

As shown in the figure, the ultrasonic motor 1 includes a piezoelectric element 2, a resonator (collar) 3. A connector 5 containing a wire 4, a fixing pole 16, and a fixing bolt 6
A rotor 8 is rotatably supported via a bearing 7 on the upper part of the rotor 8.
and a pin 10 for frictional torque transmission, which is interposed between the rotor 8 and the tip surface (elliptical vibration generation surface) 9 of the beam 4 and fixed to the tip surface 9 of the scallop 4, and a disc spring 11. It consists of a crimp force adjustment nut 12 for crimp-bonding the rotor 8 to the upper surface of the pin 10 on the tip end surface 9 of the beam 4, and the like.

Reference numeral 13 indicates a terminal board.

The connector 5 is composed of a disk portion 14 as a base and a beam 4, and the beam 4 has a concave portion 15 formed in the axial center so that the beam 4 is centered on the axial center 16. It is formed into a horn shape that is divided into two beam parts. Each beam portion has a negative side 17 as a vertical surface and the other side 18 as a curved surface, and the shape of each beam portion is symmetrical about the axis 16. That is, the beam 4 is formed into a horn shape so that vibrations, particularly longitudinal vibrations, are amplified by the horn effect.

The fixing bolt 6 protrudes through the disk portion 14 and the base of the beam, rotatably supports the rotor 8 on this protruding shaft, and is screwed into a threaded portion 19 at the end of the shaft. For adjusting the crimping force) 12. Rotor 8 via disc spring 11
It is configured so that it can be brought into pressure contact with the upper surface of the pin 10 with a predetermined pressure force.

The tip surface 9 of each beam portion is set on a plane whose center line passes through the axis 16 and is orthogonal to the axis 16. A pin 10 for friction transmission is fixed to the tip surface 9 of each beam. The pin 10 is made of steel, stainless steel, or ceramics with an HRC of 40 or higher. Further, as shown in FIG. 2, the pin IO is composed of a pin head 21 and a press-fit shaft portion 22 having a smaller diameter than the pin head 21.
The pin 10 is press-fitted and fixed to each tip surface 9 by press-fitting the press-fit shaft portion 22 into a hole 23 formed in the tip surface 9 of each beam portion in the direction of the axis 16. Further, the compression depth of the pin 10 is determined by the stepped portion 24.

The rotor 8 has a disk spring 11. Each pin 1 through nut 12
The top surface 25 of each pin 10 is pressed against the top surface 25 of each pin 10.
The rotary torque is transmitted to the rotor 8 through the rotor 8.

In the ultrasonic motor 1 configured as described above, vibrations in the vertical direction (thickness direction) generated in the piezoelectric element 2 are transmitted to the connector 5, and elliptical vibrations are generated on the tip surface 9 of the connector 5. Since the pin 10 is press-fitted and fixed to the tip surface 9, the pin 10 also vibrates elliptically together with the tip surface 9. Rotor 8 has pin lO
Since it is pressed against the upper surface 25 of the pin 10, the upper surface 25 of the pin 10
Rotational torque is transmitted from the rotor 8 to the rotor 8, and the rotor 8 rotates.

As described above, in this embodiment, since the elliptical vibration generated at the end surface 9 of each beam is transmitted to the rotor 8 via the pin 1O, conventionally, materials with excellent wear resistance and acoustic vibration characteristics have been used. Ultrasonic motor materials have been required to satisfy these conditions, which do not necessarily match, but these characteristics can now be shared between the connector 5 and the pin 10, making it possible to use materials with better characteristics. Due to wear resistance,
It becomes possible to manufacture an ultrasonic motor 1 with extremely improved acoustic vibration characteristics.

Further, since the pin 10 is fixed by press-fitting, it can be easily assembled, and automatic assembly is also possible. Furthermore, since the amount of protrusion of the pin 10 is determined by the stepped portion 24 of the pin 10, a plurality of pins 10
When press-fitting and fixing, uniform contact with the rotor 8 is possible, and pin height adjustment by post-processing of the upper surface of the pin 10 after press-fitting the pin 10 is unnecessary.

From the above, according to this embodiment, it is possible to manufacture an ultrasonic motor 1 with a simple configuration, excellent wear resistance, excellent acoustic vibration characteristics, extremely good performance, low cost, and long life.

(Second Embodiment) A second embodiment of the present invention is shown in FIGS. 4a, b, and 5. The feature of this embodiment is that the press-fit shaft portion 22 of the pin 10 in the first embodiment is replaced with a screw shaft. 30, and is configured so that it can be freely screwed into a screw hole 31 provided in the tip end surface 9 of each beam portion. Since the other configurations are the same as those in the first embodiment, similar components are given the same reference numerals and explanations thereof will be omitted.

According to the above configuration, the pin 10 can be attached to and detached from the end surface 9 of each beam portion, and therefore, when the pin 10 is worn out, it can be easily replaced. As a result, there is an advantage that the life of the ultrasonic motor 1 can be further extended. Other functions and effects are the same as those of the first embodiment, so their explanation will be omitted.

(Third example) 511a, b, and c show a third embodiment of the present invention.

In this embodiment, the pin 10 in the first embodiment is formed into a cylindrical pin 10 as shown in FIG. It is constructed by being press-fitted and fixed into holes 40 formed in parallel. Hole 40
An opening 41 having a constant width in the axial direction of the hole 40 is provided at the tip 9.
is formed so that when the pin 10 is press-fitted into the hole 40, the upper surface of the pin 10 protrudes above the tip surface 9.

Since the other configurations are the same as those in the first embodiment, similar components are given the same reference numerals and explanations thereof will be omitted.

According to the above configuration, the pin 10 and the rotor 8 are in line contact in the radial direction, and the elliptical vibration from the connector 5 is transmitted to the rotor 8 through this line contact portion. In this case, the elliptical motion transmitted through line contact draws one trajectory, and the speed direction coincides with the rotation direction. Furthermore, since the contact area is small, there is an advantage that noise generation during rotational torque transmission can be reduced. Also, pin 10
It is also extremely easy to assemble.

Other functions and effects are the same as those of the first embodiment, so their explanation will be omitted.

Note that the shape of the pin 10 is not limited to a cylindrical shape; for example, as shown in FIGS. Good too.

Similar effects can be obtained with the various pin shapes mentioned above, especially the sixth pin shape.
The shape shown in FIG. f has the advantage that the connection between the pin 10 and each beam portion is strong.

〔Effect of the invention〕

As described above, according to the present invention, the acoustic vibration characteristics and wear resistance required of the connector can be shared between the connector and the friction torque transmission pin, and the structure is extremely simple and has good performance. In addition, an inexpensive and long-life ultrasonic motor can be obtained.

[Brief explanation of drawings]

1 is a partially sectional front view showing a first embodiment of an ultrasonic motor according to the present invention; FIG. 2 is a perspective view of the main parts of FIG. 1; FIG. FIG. 4a is an exploded perspective view of the main parts of the figure, and FIG. perspective view of the section;
FIG. 5 is an exploded perspective view of the main parts of FIG. 4a, and FIG. 6a is
FIG. 6 is a partially sectional front view showing a third embodiment of the ultrasonic motor according to the present invention; FIG. 6 is a perspective view of the main part of FIG. 6 a; FIG. FIG. 6 is a perspective view showing another example of the configuration of the main part of FIG. 6a. 5... Connector 8... Rotor 9... Elliptical vibration generating surface lO... Pin

Claims (3)

[Claims] (1) An ultrasonic motor configured such that a rotor is pressed against a surface of a connector where ultrasonic elliptical vibrations are generated, and the rotor is rotated using the elliptical vibration as a driving source, wherein the ultrasonic wave in the connector An ultrasonic motor characterized in that a friction torque transmitting pin made of stainless steel, iron with an HRC of 40 or higher, or ceramic is provided on an elliptical vibration generating surface so as to protrude from the ultrasonic elliptical vibration generating surface. (2) The friction torque transmission pin is composed of a large-diameter head and a small-diameter shaft portion that is smaller in diameter than the head, and the ultrasonic elliptical vibration of the pin is generated at the stepped portion of the head and the small-diameter shaft portion. 2. The ultrasonic motor according to claim 1, wherein the ultrasonic motor is configured such that the height of the protrusion from the surface is constant. (3) A hole parallel to the vibration generation surface is provided near the ultrasonic elliptical vibration generation surface, and a friction torque transmission pin is inserted and fixed into the hole so that its upper surface protrudes from the vibration generation surface. 2. The ultrasonic motor according to claim 1, wherein the rotor and the pin are in line contact.