JPH07135786A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To omit an adjusting mechanism by providing a conical spiral spring for pressing a rotor to a stator, forming the contact to the rotor at the maximum diameter part of the spiral spring, and aligning the contact part of the spiral spring and the rotor with the contact part of the rotor and the stator in the direction of the axial line. CONSTITUTION:A rotor 7 is coupled with an output shaft 8 between bearings 2 and 9. A rim-shaped protruding part 7a formed along the outer periphery of the rotor 7 is pushed on an abrasion resistance coating layer 6 of a stator 5. A spiral spring (SS) 10 for pushing the rotor 7 to the abrasion resistance coating layer 6 of the stator 5 is arranged in a space between the bearing 9 and the rotor 7. The rotor 7 is energized toward the stator with the SS 10. The maximum diameter part of the SS 10 comes into contact with the rotor 7 at a position on the same axial line as the contact position of the rotor 7 and the stator 5. Namely, the contact position of the SS 10 and the rotor 7 are alinged in the direction of the axial line with respect to the contact position of the rotor 7 and the stator 5. Therefore, an adjusting mechanism is not required.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration wave motor or an ultrasonic wave motor.

[0002]

2. Description of the Related Art Circulating vibration is generated in a stator (oscillator) constructed by attaching an electro-mechanical energy conversion element such as a piezoelectric element to an elastic body, so that a rotor or a moving body pressed against the stator is continuously unidirectionally moved. Vibration wave motors or ultrasonic wave motors configured to generate various mechanical movements have already been put to practical use by the applicant of the present invention as motors for precision equipment and are widely known.

In a conventionally known ultrasonic motor, a plurality of strip-shaped leaf springs arranged radially with respect to the axis are used as springs for pressing the rotor against the stator. This is because the motor can be made thinner (axial length can be shortened) by using the leaf spring.

[0004]

However, although the use of a leaf spring radially arranged with respect to the shaft center as a spring for pressing the rotor to the stator is effective in reducing the thickness of the motor, the leaf spring is a spring. Since the constant is large, there is a drawback in that the applied pressure fluctuates greatly with a small amount of displacement, resulting in a large fluctuation in the output torque of the rotor. Therefore, conventionally, the ultrasonic motor having the above-mentioned structure has a drawback that an adjusting mechanism is required to adjust the output fluctuation of the rotor, resulting in a high assembly cost.

It is an object of the present invention to provide an improved ultrasonic motor that does not require the adjusting mechanism and does not increase the size of the motor.

[0006]

Various springs are conceivable for pressing the rotor to the stator.
As a result of various attempts, the present inventor has adopted a frustoconical or conical spiral spring as a spring that meets the conditions that the change in the applied pressure with respect to the displacement amount is small and the motor does not increase in size. did.

[0007]

The improved ultrasonic motor according to the present invention requires less assembly steps than conventional ones and is therefore low in cost.
In addition, there is no fear of increasing the size.

[0008]

Embodiments of the ultrasonic motor according to the present invention will be described below with reference to the drawings.

FIG. 1 is a vertical sectional view showing a schematic structure of an ultrasonic motor according to a first embodiment of the present invention. In the figure, 1 is a base or base that constitutes the end plate of the motor,
A motor cover, that is, a case 11 is coupled to the base 1 by bolts or the like, and the base 1 and the case 11 form an external housing of the ultrasonic motor. A bearing mounting hole is provided on the outer surface of the base 1, and a bearing 2 is fitted and fixed in the hole, and an output shaft 8 is rotatably fitted in the bearing 2 and the shaft 8 is case 11 It is rotatably supported by another bearing 9 fixed to the base 1 and the case 11.
Protruding outside of. A cylindrical portion 1 having a central hole with an inner diameter larger than the outer diameter of the shaft 8 on the inner surface of the base on the back side of the bearing 2.
a is projected, a wheel-shaped stator 5 is fitted to the outer peripheral surface of the tubular portion 1a at the central tubular portion 5a, and is fixed by caulking the tip of the tubular portion 1a. There is. The stator 5 is made of an elastic material such as metal, and its outer peripheral portion is a vibrating portion constituted by an annular thick layer, and a wear-resistant coating layer 6 is formed on one end surface of the annular vibrating portion. The piezoelectric element 4 is adhesively fixed to the other end surface of the vibrating portion in a ring shape. A flexible printed circuit board 3 as a power feeding means for applying a driving voltage to the piezoelectric element 4 is adhered to a part of the piezoelectric element 4 and is drawn out of the case 11.

A rotor 7 is fitted on the output shaft 8 between the bearing 2 and the bearing 9, and a rim-shaped projection 7a formed along the outer peripheral edge of the rotor 7 has a wear-resistant coating layer 6 on the stator 5. Pressed on. A spiral spring 10 for bringing the rotor 7 into pressure contact with the wear-resistant coating layer 6 of the stator 5 is arranged in the space between the bearing 9 and the rotor 7, and the spring 10 attaches the rotor 7 toward the stator 5. It is energized. The maximum diameter portion of the spring 10 is at the same axial position as the contact position between the rotor 7 and the stator 5 and
Is in contact with. That is, the contact position between the spring 10 and the rotor 7 is aligned with the contact position between the rotor 7 and the stator 5 in the axial direction.

As described above, in the ultrasonic motor of this embodiment, the spiral spring, which has a smaller spring constant than the leaf spring and whose change in the applied pressure with respect to the displacement amount is smaller than that of the leaf spring, is used as the pressing means of the rotor. Therefore, it does not require the adjustment mechanism used in conventional ultrasonic motors,
Therefore, the cost can be reduced as compared with the conventional ultrasonic motor.

Next, the structure of the ultrasonic motor of the second embodiment of the present invention will be described with reference to FIG.

The present embodiment is different from the structure of the first embodiment in that the spiral spring of the first embodiment is replaced with a spiral leaf spring 12 formed by spirally winding a strip-shaped plate material. The other structure is the same as that of the first embodiment. Therefore, in FIG. 2, the same components as those of the first embodiment are indicated by the same reference numerals as those in FIG. 1 and the description thereof will be omitted.

The spiral leaf spring 12 used in this embodiment also has a smaller spring constant than the leaf spring used in the conventional ultrasonic motor and has the same characteristics as the spiral spring. The ultrasonic motor can also achieve the same effect as that of the first embodiment, and since the spring 12 used in this embodiment can be manufactured by press working, it is more cost-effective than the motor of the first embodiment. It is possible to reduce.

[0015]

As described above, in the improved ultrasonic motor according to the present invention, a spiral spring or a spiral leaf spring is used instead of the conventional leaf spring as a spring for pressing the rotor against the stator. Therefore, the change in the pressing force with respect to the spring displacement becomes small, and as a result, the adjustment mechanism required in the conventional ultrasonic motor becomes unnecessary, and the ultrasonic motor that can be manufactured at a lower cost than the conventional ultrasonic motor can be provided.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a schematic structure of an ultrasonic motor according to a first embodiment of the present invention.

FIG. 2 is a vertical sectional view showing a schematic structure of an ultrasonic motor according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Base 2, 9 ... Bearing 3 ... Flexible printed circuit board 4 ... Piezoelectric element 5 ... Stator 6 ... Wear-resistant coating layer 7 ... Rotor 8 ... Output shaft 10 ... Spiral spring 11 ... Case 12 ... Spiral leaf spring

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshio Sakai, Canon Seiki Co., Ltd. 2-4-19 Nakane, Meguro-ku, Tokyo

Claims (2)

[Claims] 1. A stator in which an exciting element such as a piezoelectric element is fixed and which is excited by the exciting element to generate a traveling wave vibration in a circumferential direction on one end face, and is pressed against the end face of the stator. In the ultrasonic motor having a rotatable rotor, a frustoconical or conical spiral spring is provided as a pressurizing means for pressing the rotor to the stator, and the spiral spring has its own maximum diameter portion. An ultrasonic motor, wherein the ultrasonic motor is in contact with the rotor, and a contact portion between the spiral spring and the rotor is axially aligned with a contact portion between the rotor and the stator. 2. The ultrasonic motor according to claim 1, wherein the spiral spring is formed by punching out a plate-shaped spring material.