JPS63213477A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To improve the durability of an ultrasonic motor by securing a slider made of an organic material which contains specific fine solid powder to a position where a stator is in contact with a movable element of a rotor 1. CONSTITUTION:A polarized piezoelectric unit 4b is secured to an elastic unit 4a in the stator 4 of an ultrasonic motor, and when a high frequency voltage is applied to the unit 4b, a traveling wave is generated. A slider 2a is secured to a rotor ring 2b in a movable element (rotor) 2, and since one side surface 4c of the stator 4 is in contact with the slider 2a each other and the side of the stationary unit 3a with the shaft 1 of the rotor 2 is pressed by the flange of a bearing 9, the stator 4 is in contact under pressure with the rotor 2 to be rotated. In this case, the slider 2a in contact with the stator 4 is formed of aromatic polyester resin and ethylene tetrafluoride resin, and fine solid aluminum oxide powder is uniformly distributed on the surface. Thus, it can prevent the wearing powder of the slider 2a, etc., from disturbing the rotation.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention involves fixing a piezoelectric element on which an excitation electrode is formed to an elastic body, applying a voltage to the piezoelectric element, and combining a transverse wave and a longitudinal wave. The present invention relates to an ultrasonic motor consisting of a stator that generates traveling waves and a rotor/mover that rotates or moves while being in pressure contact with the surface of the stator.

[Conventional technology]

A traveling wave motor and an ultrasonic motor device that utilize bending vibration (ultrasonic vibration) of a piezoelectric body are disclosed in Japanese Patent Laid-Open No. 60-1
No. 83982, Japanese Patent Application Laid-open No. 60-22479, etc., the present invention relates to the rotor/
This relates to a moving element.

The sliding body constituting the conventional rotor/slider was made of an elastic body (urethane resin) with a high coefficient of friction, but
After 0 hours of operation, friction powder from the stator adhered to the sliding body, resulting in a decrease in performance.

[Problem that the invention seeks to solve]

As mentioned above, in ultrasonic motors that utilize traveling waves, K is used to extract strong torque and improve conversion efficiency.
Since the stator and rotor/slider are strongly pressed against each other and receive the driving force, there is a problem in that the contact area between the stator and rotor/slider is prone to wear, which significantly deteriorates durability. there were.

An object of the present invention is to provide a means for further improving the durability of a traveling wave ultrasonic motor by showing the structure of a contact portion between a stator and a rotor/mover.

[Means for solving problems]

The present invention provides that when the stator of a traveling wave ultrasonic motor is made of metal such as phosphor bronze, brass, carbon steel, tool steel, stainless steel, or ceramics, a portion where the rotor/scillator contacts the stator, Polyamide resin, polyimide resin, polyamideimide resin, polyester resin, containing solid fine powder of aluminum oxide, carbon, molybdenum disulfide, cerium oxide, iron oxide, calcium fluoride, calcium phosphate, silicon oxide, etc. with a particle size of 1 μm or less, fluororesin,
A sliding body made of organic materials such as epoxy resin, acrylic acid resin, phenol resin, silicone resin, melamine resin, methyl methacrylate resin, polypropylene resin, urea resin, aniline resin, acrylonitrile resin, nylon, and vinyl chloride resin is fixed. If the sliding body of the rotor/scillator has lower wear resistance than the metal or ceramic stator, use solid fine powder to protect the sliding body and replace the metal or ceramic stator. If the wear resistance is inferior to that of the sliding body, the solid fine powder has the effect of protecting the metal or ceramic stator.

In addition, if the stator metal or ceramic has inferior wear resistance than solid fine powder or sliding body, stator metal oxides, carbides, nitrides, titanium carbides, titanium nitrides, chromium, etc. A film made of one or more hard materials is formed on the surface of the stator to protect the stator.

The solid fine powder is used in the early stages of operation of an ultrasonic motor to reduce unevenness by scraping off minute convexities in the contact area between the stator and rotor/mover, thereby ensuring tight contact between the stator and rotor/mover. west,
The material of the stator, metal or ceramic, can be selected to have the effect of extracting the driving force more efficiently.

Solid fine powder can cause wear powder from the stator or sliding body to excessively adhere to mutual contact surfaces after the initial operation of the ultrasonic motor, inhibiting the transmission of driving force from the stator to the rotor/mover. In addition, the type and content density can be appropriately selected and used so as to prevent the effect of inhibiting the rotation/movement of the rotor/mover.

〔Example〕

The stator 4 of the ultrasonic motor has a structure in which a polarized piezoelectric material 4b is fixed to an elastic material 4a. When a high frequency voltage (the electrical system is not shown) is applied to the piezoelectric material 4b, the stator 4 generates bending vibration. A traveling wave is generated by

The mover 2 (hereinafter referred to as rotor) has a structure in which a sliding body 2a is fixed to a rotor ring 2b.

One surface 4c of the stator 4 is in mutual contact with the sliding body 2a, and the side surface of the fixed part 6a of the rotor 2 to the shaft 1 is pressed by the flange part of the bearing 9, so that the stator 4
and rotor 2 are in pressurized contact. As a result, rotor 2
is a photograph showing the surface condition of the traveling wave wavefront 4c. The sliding body is made of aromatic polyester resin and tetrafluoroethylene resin, and solid fine powder of aluminum oxide is uniformly distributed on its surface. The solid fine powder can be incorporated by a method of mixing the organic material as a raw material in advance and then molding the organic material. Furthermore, by pressing solid fine powder during surface processing of the organic material, it can be made to sink into the organic material.

For example, by scattering an appropriate amount of solid fine powder on a lapping machine, applying a load to the organic material fixed to the rotor in the manner of lapping, and pressing it for a certain period of time, it can be distributed near the surface of the organic material at a desired density. Can be done. The rotor manufactured in this way was combined with a stator made of phosphor bronze.
When the surfaces of the rotor and stator were observed after 0 hours of operation, the surfaces were smooth, and an organic material containing fine solid powder was adhered very thinly and uniformly to the stator surface.

This is shown in Photo 1b. I drove this again for a long time,
Almost no wear occurred thereafter.

Samples with alumina oxide and graphite powder fixed to them using the same organic materials as above, and samples with alumina oxide fixed to the surface of polyamide-imide resin containing graphite also showed almost no wear.

On the other hand, when a sample made of aromatic polyester resin and 47-fluorinated ethylene resin and containing no aluminum oxide powder on the surface was operated in combination with a rotor and a phosphor bronze stator (shown in σf2a), A thick, non-uniform organic material film was observed to adhere to the stator surface (Photo 2b), and operation became impossible in a short period of time.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the mutual durability between the stator and rotor/mover of a traveling wave ultrasonic motor can be improved.

[Brief explanation of the drawing]

The drawings show one embodiment of the ultrasonic motor according to the present invention, with FIG. 1 showing an exploded perspective view and FIG. 2 showing an assembled sectional view of FIG. 1. Photograph 1a shown in FIG. 3 is a 500x photograph of the surface of a sliding body made of polyester resin containing solid fine powder of aluminum oxide of the present invention and tetrafluoroethylene resin. Photograph 1b shown in FIG. 3 is a 500x photograph of the upper surface of the stator made of phosphor bronze operated in combination with the photograph 1a, including the groove portion shown at 40 in FIG. 1. Photograph 2a shown in FIG. 4 is a 500x photograph of the surface of a sliding body made of polyester resin containing no solid fine powder and 47-fluorinated ethylene resin. Photo 2b shown in FIG. 4 is a 500x photo of the top surface of the stator made of phosphor bronze, including the groove shown at 40 in FIG. 1', which was operated in combination with photo 2a. 1... shaft, 2... rotor, 2a.
...Sliding body. 2b...Rotor ring s 6a...
Fixed part with rotor shaft, 4...Stator, 4
a...Elastic body, 4b...Piezoelectric body,
4C... Traveling wave generation surface of stator, 6.9...
...Bearing, 7...Case, 8...
···cover. Patent applicant Citizen Watch Co., Ltd. Figure 2 C%4c'M -y='

Claims (2)

[Claims] (1) A stator in which a piezoelectric element having an excitation electrode formed thereon is fixed to an elastic body, a voltage is applied to the excitation electrode to generate a traveling wave that is a combination of a transverse wave and a longitudinal wave, and a surface of the stator. In an ultrasonic motor consisting of a rotor/mover that rotates or moves while being in pressurized contact with An ultrasonic motor characterized by being made of organic material. (2) The sliding body is based on an organic material and is made of one or a mixture of two or more of solid fine powders of inorganic materials such as aluminum oxide, molybdenum disulfide, cerium oxide, and carbon. The ultrasonic motor according to item 1.