JPS62196082A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To suppress the generation of noise and increase driving torque and reduce abrasion loss, by organizing a stationary section with a fitted piezo-electric unit, with a composite plastic member including fiber at least. CONSTITUTION:A moving section 3 is made to come in pressure contact with a stationary section 1 with a fitted piezo-electric unit 2, and on the piezo-electric unit 2, slight oscillation along with a progressive wave is generated. The moving section 3 is moved by the slight oscillation via a frictional force. The stationary section 3 is organized with a plastic member including fiber at least, for example, a plastic member including approx. 70% carbon fiber.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a motor that can be driven by generating ultrasonic vibrations accompanied by traveling waves using a piezoelectric body.

Conventional technology In an ultrasonic motor, when a fixed part and a moving part are pressed into contact with each other, the vibration of the fixed part accompanied by a traveling wave caused by a piezoelectric body is transmitted to the moving part through frictional force. is driven. The starting torque, no-load rotation speed, and
It is one of the factors that determines motor characteristics such as motor efficiency and life. In an ultrasonic motor in which a movable part is brought into pressure contact with a fixed part equipped with a piezoelectric body, and the movable part is moved by minute vibrations accompanied by traveling waves of the piezoelectric body, the fixed part has conventionally been made of metal. Furthermore, the moving part was also made of metal. Another method has been to attach a third object called a slider, which has a high coefficient of friction, such as rubber, to the moving part and bring it into pressure contact with the fixed part. moreover,
In order to efficiently transmit the ultrasonic vibrations generated from the piezoelectric material,
It has been proposed that the fixing part preferably has a shape with a plurality of slits.

Problems to be Solved by the Invention There is still no ultrasonic motor that achieves good performance as a motor at the contact surface between the fixed part and the moving part and is suitable for practical use. In metal-to-metal contact where the fixed part is made of metal materials such as stainless steel, aluminum, or steel, and the moving part of the metal is used, the contact surfaces of the fixed part and rotating part are subjected to ultra-precision machining to achieve flat surface machining accuracy on the order of microns. I needed to. Furthermore, under ultrasonic vibration, noise is generated due to metal-to-metal contact, which is a practical problem. As non-metallic contacts, proposals have been made after the idea of a slider, such as sliders with anisotropy, sliders with flexibility, and sliders with a large coefficient of friction such as rubber. When such friction materials are used, the wear caused by the friction of the contact surfaces causes deterioration of various performances such as starting torque, no-load rotation speed, efficiency, etc., and the life of the motor is extremely short. It has disadvantages, and requires an extra component called a slider, making the structure complicated.Furthermore, if the fixing part is made of metal material with multiple slits, cutting is time-consuming; It was extremely difficult to create the fixing part.

The requirements for the fixed part of a practical ultrasonic motor are as follows:
(1) It can be easily manufactured, (2) The motor is low in noise when driven, (3) The driving force (torque) generated by pressurized contact with the moving part is large, (4) The motor The following four points can be mentioned: the amount of wear caused by the friction of the contact surfaces during driving is as small as possible, and performance can be maintained stably for a long period of time.

1φ- Means for solving the problem A moving part is brought into pressure contact with a fixed part equipped with a piezoelectric body,
In an ultrasonic motor in which a moving part is moved by ultrasonic vibration accompanied by a traveling wave of a piezoelectric body, a fixed part is made of a composite plastic material containing a small amount of fiber.

By constructing the working and fixing part from a composite plastic material containing at least fibers, no noise is generated due to metal-to-metal contact. Furthermore, since the fixed part made of this composite plastic material can also serve as a slider, which has been proposed in the past, on the contact surface with the moving part, there is no need to use an extra component called a slider, and the structure is simplified. Since it contains fibers, it is possible to reduce the amount of wear caused by friction between the contact surface with the moving part.In addition, when constructing the fixed part with such a composite plastic material, the slit It also has the advantage that complex shapes can be easily created compared to metal processing.

EXAMPLE A prepreg made by impregnating a carbon fiber woven fabric made of continuous fibers with an epoxy resin was wound up using a mandrel by a conventional tube winding method and preformed into a ring shape. At that time, in order to create a structure with multiple slits, the slit portions were cut in advance before winding. This temperature is 15
The resin was left to stand for 2 hours at 0° C. and a pressure of 10 kg/cd to harden the resin, and a ring-shaped molded product was obtained.

Here, the volume content of carbon fiber was about 70%.

Alternatively, after creating a cylindrical molded body, it can be cut into a structure with slits. The obtained annular molded body is as shown in FIG.
The fibers are oriented in the axial direction, whereas they are not oriented in the direction C away from the center. Therefore, the obtained molded body had anisotropy in elastic modulus.

This annular molded body was used as a fixed part 1, and a piezoelectric body 2 was attached using a commercially available adhesive, and the movable part 3 was brought into pressure contact with the fixed part by utilizing its gravity. Here, the moving part 3 is made of metal as a material with good thermal conductivity so that frictional heat can be dissipated. When the ultrasonic motor obtained in this way is driven by vibration accompanied by a traveling wave caused by the piezoelectric body 2, there is no squeaking noise compared to the conventional case where the fixed part was made of metal material. There was no noise. In addition, as for the driving force, by adjusting the contact pressure force, a driving force equal to or higher than that in the case of metal-to-metal contact or the case of contact using a slider was obtained.

This seems to be because the use of fibers in the fixed part makes it possible to have a structure with anisotropic elastic modulus and to efficiently transmit vibrations to the movable part. Additionally, an extra component called a slider is not required, making the configuration of the ultrasonic motor extremely simple and easy to manufacture.

Furthermore, after actually driving the ultrasonic motor one million revolutions, the depth of wear was measured using a surface profile measuring device. It was the fixed part that was worn, and the amount of wear was very small at 3.0 μm even after 1 million cycles. Furthermore, no change in rotational speed or generation of noise was observed during driving, and the motor was rotating under the same conditions as the initial state. The driving conditions are a step rotation with a rotation angle of 90'' and a load of 300gf・Cl1.
1, and the apparent rotational speed was 100 rpm. This is much less than the amount of wear between metals under the same conditions. Furthermore, for comparison, a commercially available friction material with a comparatively high coefficient of friction, which has been conventionally used as a clutch lining material, was tested as a slider in a method that involved a slider. In the case of the comparative example, approximately 5
It stopped after spinning 10,000 times. At this time, the abrasion was severe and about 60 μI was removed after about 50,000 cycles, and the number of revolutions decreased as the drive progressed, making it unfit for practical use.Also, some noise was generated during drive.

Here, we have described in detail the case where carbon fiber is used as the fiber, but in addition to that, glass fiber, silicon carbide fiber,
Alumina fiber, aromatic polyamide fiber, quartz fiber, etc. can be used. Furthermore, although epoxy resin, which is a thermosetting resin, was used as the resin, thermofusible resins and other thermosetting resins can also be used.

Although the shape of the ultrasonic motor is shown as an annular one, the same applies when the fixing part of the ultrasonic motor has a disc-shaped structure as shown in Fig. 2 and is made of a composite plastic material containing fibers. Good results are obtained. By constructing the fixing part from a composite plastic material containing fibers as in this embodiment, there is also the advantage that it is lighter in weight compared to the case where it was conventionally constructed from metal.

Effects of the Invention According to the present invention, it is possible to realize an ultrasonic motor that can be practically provided, which hardly causes any deterioration or deterioration of motor performance due to wear, has a large torque, and makes no noise during motor rotation.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the configuration of an annular ultrasonic motor;
FIG. 2 is a perspective view showing the configuration of a disc-shaped ultrasonic motor.

Claims (7)

[Claims] (1) In an ultrasonic motor in which a movable part is brought into pressure contact with a fixed part equipped with a piezoelectric body, and the movable part moves through frictional force due to minute vibrations accompanied by traveling waves of the piezoelectric body,
An ultrasonic motor characterized in that the fixing part is made of a composite plastic material containing at least fiber. (2) The ultrasonic motor according to claim 1, wherein the fixed portion contains fibers and thus has anisotropy in elastic modulus. (3) Claim 1 in which the fiber is at least one of the group consisting of carbon fiber, glass fiber, silicon carbide fiber, alumina fiber, aromatic polyamide fiber, and quartz fiber.
Ultrasonic motor as described in section. (4) The ultrasonic motor according to claim 1, wherein the fibers are continuous fibers. (5) The ultrasonic motor according to claim 1, wherein the fixing portion has a shape with a plurality of slits. (6) The ultrasonic motor according to claim 1, wherein the moving part is made of metal at least at the contact surface with the fixed part. (7) The ultrasonic motor according to claim 1, wherein the ultrasonic motor has an annular shape or a disk shape.