JP3295075B2 - Ultrasonic motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotating support structure for a moving body of an ultrasonic motor.

[0002]

2. Description of the Related Art In a conventional ultrasonic motor, when a bearing is used to support the rotation of a moving body, the moving body is rotatably incorporated through a bearing about a central axis. The value was not configured.

[0003]

In an ultrasonic motor, an alternating voltage is applied to a piezoelectric element bonded to an elastic body, and a flexural vibration wave is generated in the vibrating body by the expansion and contraction of the piezoelectric element. The moving body contacted by pressure is moved by frictional force. For example, in the case of the traveling wave type ultrasonic motor, the contact state between the vibrating body and the friction material joined to the moving body is as shown in FIG. Since it is driven by frictional force, it is ideally desirable that the wave fronts of all traveling waves uniformly contact the sliding surface of the friction material. However, it is impossible for a piezoelectric element to generate a truly uniform traveling wave due to variations in pattern shape and polarization state. Further, it is impossible for the sliding surface of the friction material to have a truly uniform contact state due to manufacturing variations. Therefore,
In order to obtain a motor with higher efficiency, it is necessary to have a portion that absorbs the above-mentioned variation in the structure of the motor.
When a bearing is used for rotationally supporting the moving body, an abrasion portion of the bearing plays the role. Therefore, when the amount of rubbing of the bearing is extremely small, the variation cannot be absorbed, the contact state becomes nonuniform, slippage occurs, and motor performance deteriorates.

Accordingly, an object of the present invention is to solve such a conventional problem and to provide a highly efficient motor.

[0005]

In order to solve the above-mentioned problems, in the present invention, the amount of abrasion in the thrust direction of a bearing used for supporting the rotation of a moving body is determined by the amount of amplitude of a vibration wave generated in the vibrating body. Alternatively, the structure is made larger than the larger one of the undulation amounts of the friction material sliding surface. Here, the amount of abrasion in the thrust direction of the bearing is, as shown in FIG. 2 (a), from the state where the outer ring 201 has risen upward through the ball with respect to the inner ring, and FIG.
As shown in the figure, the total amount of movement in the vertical direction when the outer wheel 204 changes to a state in which the outer wheel 204 moves downward with respect to the inner wheel via a ball.

By increasing the amount of abrasion in the thrust direction of a bearing used for rotationally supporting the moving body to be larger than the amplitude of the traveling wave generated in the vibrating body, the degree of freedom of the moving body in the vertical direction is increased, and the vibration wave is increased. The moving object automatically tries to follow the most stable contact state even if the distance becomes uneven.
Also, by increasing the amount of abrasion in the thrust direction of the bearing over the amount of waviness of the friction material sliding surface, the degree of freedom increases, preventing the contact surface with the vibrating body from hitting one side, and providing a more uniform contact state. Become.

[0007] From the above operation, the vibration of the vibrating body can be efficiently transmitted to the moving body, and a highly efficient ultrasonic motor can be provided.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a basic configuration of an ultrasonic motor according to the present invention. The vibrating body 106 is made of a metal such as Al, and a PZT piezoelectric element 107 that has been subjected to polarization processing is adhered to the vibrating body 106 and is driven into the central axis 109. Vibrating body 106
Has a plurality of comb-shaped protrusions 106 a in order to expand the vibration caused by the piezoelectric element 107, and the tip surface thereof serves as a contact surface with the moving body 104. The moving body 104 is provided with a frictional material 10 made of a composite plastic
5 is adhered, and the outer ring 103 of the bearing 103 is
a has been implanted. Inner ring 10 of this bearing 103
3b is set on the central axis 109 of the vibrating body 106 to form a motor. Also, the inner ring 103b of the bearing 103
Is pressed by the pressure spring 102 and applies a pressing force to the contact surface between the vibrating body 106 and the friction material 105 via the ball 111.

When a motor having an outer diameter of a vibrating body of φ10 mm was actually manufactured, the amplitude of the vibrating body in a no-load state was 1
２2 μm. The swell of the friction material is 5-1.
It was about 0 μm. Experiments were conducted with this motor with various amounts of bearing akiki.
Those with a μ or less had extremely poor rotation performance. Also,
The sliding noise was also loud, and it was found that slippage occurred.
Therefore, in this case, it is desirable that the amount of rake of the bearing is larger than the amount of undulation of the friction material.

[0010]

As described above, according to the present invention, when a bearing is used in a rotating support structure of a moving body of an ultrasonic motor, the amount of abrasion in the thrust direction is determined by the amplitude of the vibration wave generated in the vibrating body. Or, by increasing the amount of undulation of the friction material sliding surface, the degree of freedom in the vertical direction of the moving body is increased, and the variation of the vibrating body and the friction material is absorbed. As a result, a stable contact state is achieved, and an efficient ultrasonic motor can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view of an ultrasonic motor having a moving body rotation support structure according to the present invention.

FIG. 2 is a cross-sectional view showing the amount of aki of a bearing according to the present invention.

FIG. 3 is a sectional view showing a contact state of the ultrasonic motor according to the present invention.

[Description of References] 101 ... female screw 102 ... pressurizing spring 103 ... bearings 104, 301-moving body 105, 302-friction material 106, 303- Vibrating body 107 Piezoelectric element 108 Lead wire 109 Central axis 110 Fixed base 103a, 201, 204 Outer ring 103b, 202 , 205 ・ ・ Inner ring 111、203、206 ・ ・ Ball

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-63-277480 (JP, A) JP-A-62-64278 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02N 2/00 F16C 19/16 F16C 25/06 F16C 35/06

Claims (2)

(57) [Claims] 1. An ultrasonic motor having a piezoelectric element, a vibrating body made of an elastic material having the piezoelectric element, and a moving body driven by vibration waves of the vibrating body, wherein a bearing for guiding rotation of the moving body. Is a ball bearing, and only one of the inner ring and the outer ring of the bearing is operable in accordance with the movement of the moving body, and the amount of clearance in which the outer ring can move in the thrust direction with respect to the inner ring of the bearing is: An ultrasonic motor, wherein the ultrasonic motor has a larger value than an amplitude of a vibration wave generated in a vibrating body or a swell amount of a vibrating body contact surface of the moving body. 2. A moving body provided with a center axis, a piezoelectric element and fixed to the center axis, and a moving body provided on the center axis via a bearing and driven by a vibration wave of the vibrating body; In an ultrasonic motor having a pressurizing unit that presses the moving body against the vibrating body, the pressurizing unit can be adjusted by a screw structure provided on the center shaft, and only one of the inner ring and the outer ring of the bearing is used. However, it is operable in accordance with the movement of the moving body, and the amount of stroke in which the outer ring can move in the thrust direction with respect to the inner ring of the bearing is the amplitude of the vibration wave generated in the vibrating body, or An ultrasonic motor, wherein the ultrasonic motor has a larger value than the larger undulation amount of the vibrating body contact surface of the body.