JPH0426385A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To realize a high efficiency and stabilize a torque by a method wherein the respective segments of a rotor are warped following the movement of a vibrator to maintain a surface contact state with the outer surface of the vibrator. CONSTITUTION:An ultrasonic motor is composed of a round rod shaped vibrator 1, a cylindrical rotor 5, a coil spring 6 which is an energizing means, etc. A plurality of slits 10 are formed in the rotor 5 along an axial direction with a certain interval along the circumferential direction to divide the rotor 5 into a plurality of segments 5a. The energizing actuating means 6 is fitted outside the respective segments 5a and actuates inward the respective segments 5a elastically so as to press the segments 5a against the outer surface of the vibrator 1. By applying a predetermined AC voltage to the vibrator 1, the end part of the vibrator 1 is moved elliptically. Then the respective segments 5a follow the movement of the end part of the vibrator 1 while they are warped outward or inward and the rotor 5 is rotated by a driving force while a surface contact state is maintained. With this constitution, a driving efficiency can be improved, local wear can be eliminated and a torque can be stabilized.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an ultrasonic motor using a round rod-shaped vibrator.
Specifically, the present invention relates to the structure of a rotor that rotates in contact with an end of a vibrator.

<Prior art> Some conventional ultrasonic motors use a round bar-shaped vibrator as a drive source.Here, the round bar-shaped vibrator is
It is a cylindrical or pipe-shaped +7) isomorphic degenerate type double mote flexural vibrator, whose schematic structure is shown in FIG.

As shown in the figure, a round rod-shaped vibrator zt is composed of a round rod 1a made of piezoelectric ceramics, and strip-shaped electrodes 1b, - or r are formed at four equal positions in the circumferential direction on the outer circumferential surface of the round rod 1a. , the round rod 1a is polarized between these electrodes 1b, in a predetermined direction shown by the arrow.

This round bar-shaped vibrator 1 moves in an elliptical manner at both ends when an alternating current voltage equal to the resonance frequency of the bending vibration of the round bar 1a is applied to each electrode 1b with a phase shift of 90°.

Conventionally, there are three types of ultrasonic motors using the round rod-shaped vibrator I as a driving source, as shown in FIGS. 5 to 8.

The one shown in FIG. 5 is said to be a - point circumscribed type, so a rotor 2 is provided in parallel at the end of the round bar-shaped vibrator 1, and a part of the outer peripheral surface of the round bar-shaped vibrator 1 is attached to the rotor 2. The blade is designed to come in contact with the outer peripheral surface of the blade.

The rotor 3 shown in FIGS. 6 and 7 is of the - point inscribed type, and the rotor 3 is formed into a cup shape, and this is connected to the round rod-shaped vibrator 1.
The vibrator I is fitted onto the end of the vibrator I so that a part of the outer circumferential surface of the vibrator I is brought into contact with the inner circumferential surface of the rotor 3.

The one shown in Fig. 8 is a multi-point inscribed type, in which the inner peripheral surface of a cup-shaped rotor 4 is tapered, and the end of a round rod-shaped vibrator l is pressed against this tapered surface 4a. It is something.

<Problems to be Solved by the Invention> By the way, the one-point circumscribed type described by Moe makes it easy to adjust the contact pressure between the round rod-shaped vibrator 1 and the rotor 2, but since the contact point is a force point, it is prone to wear. Easy to do and inefficient. Furthermore, it has the disadvantage of being large in size due to its biaxial structure.

On the other hand, in the -point inscribed type and the multi-point inscribed type in-plane type, since the axis of the vibrator l overlaps with the axis of the rotor 3.4,
It is structurally small.

However, in the - point internal contact type, since contact is made at one point on the end of the vibrator 1 or the inner peripheral surface of the rotor 3, it is prone to wear and has low efficiency, just like the - point external contact type. . Furthermore, it is necessary to align the axes of the vibrator 1 and the rotor 3 with high precision, which is a troublesome task.

On the other hand, in the multi-point internal contact type, each part of the outer circumferential surface of the vibrator 1 comes into contact with the inner circumferential surface of the rotor 3 in sequence, so the degree of wear is compared to the above two types. However, on the tapered surface of the rotor 4, the area where the circumference of the end face of the vibrator 1 contacts is worn out in the form of a circumferential groove due to local stress concentration of the driving force of the vibrator 1. However, due to this wear, the driving performance from the vibrator 1 to the rotor 4 changes and the torque becomes unstable.

The present invention has been made in view of the above-mentioned problems, and utilizes the advantages of an internal rotor by using a cylindrical rotor.
The inner circumferential surface of the rotor is brought into surface contact with the outer circumferential surface of the end of the vibrator over the entire circumference, thereby increasing driving efficiency, eliminating local wear, and stabilizing torque.

Means for Solving the Problems> In order to achieve the above problems, the present invention includes a round rod-shaped vibrator and a cylindrical rotor fitted onto the end of the vibrator, This rotor has a plurality of axial slits formed at equal intervals in the circumferential direction and is divided into a plurality of divided pieces, and each divided piece is pressed against the outer circumferential surface of the vibrator. The structure is such that a biasing means is fitted to bias the inner diameter side \ rebound.

In the above configuration, the rotor is fitted onto the end of the round rod-shaped vibrator, and in the fitted state, each divided piece of the rotor is pushed around the outer periphery of the vibrator by the elasticity of the biasing means. Pressed against the surface. When a predetermined alternating current voltage is applied to the vibrator, the ends of the vibrator move in an elliptical manner, and each divided piece follows the movement of the vibrator ends while curving outward or inward, resulting in surface contact. It rotates while receiving the driving force while maintaining its state.

<Embodiment> FIGS. 1 and 2 show an ultrasonic motor for paper feeding according to an embodiment of the present invention, with FIG. 1 being an exploded perspective view thereof, and FIG. 2 being a sectional view thereof.

The ultrasonic motor of this embodiment consists of a round rod-shaped vibrator l, a cylindrical rotor 5, a coil spring 6 as a biasing means, a roller 7, and a support shaft 8.

As explained in the prior art section, the round rod-shaped vibrator 1 has strip-shaped electrodes formed at equal positions in the circumferential direction on the outer peripheral surface of a piezoelectric ceramic round rod, and a predetermined orientation between these electrodes. It is an isomorphic degenerate type double moat bending oscillator which is polarized to f2 and has a cylindrical shape but a pipe shape. Supporting nozzles 9 are provided at two locations in the axial direction of the vibrator 1.

The rotor 5 is externally fitted onto the end of the vibrator 1 in a press-contact state, and a plurality of rotors (
In the embodiment, three (3) axial slits 10, . At the same time, on the inner periphery of the rotor 5, a stop step part 11 is formed to receive the end face of the vibrator 1, and the tip side of the stop step part 11 of the support 1 is formed with the outer diameter of the vibrator 1. The inner diameter is approximately equal to that of the

The coil spring 6 constitutes a biasing means for tightening each divided piece 5a of the rotor 5 toward the inner diameter side, and is wound around the outer periphery of the rotor 5.

The roller 7 serves as an output portion of the ultrasonic motor, and is configured to feed paper between it and other rollers (not shown) that are in circumscribed contact with the roller 7. The roller 7 is a cylindrical body coaxial with the rotor 5, and is integrally connected to the base of the rotor 5.

The support shaft 8 is fixed through the holding plate I2, and a roller 7 is provided on the protruding portion of the support shaft 8 via a bearing 13.
The rotor 5 is rotatably supported via the.

In the above configuration, each divided piece 5a of the rotor 5 is pressed against the end of the round rod-shaped vibrator 1 by the biasing elasticity of the coil spring 6, and the rotor 5 is attached to the end of the vibrator 1 over almost the entire circumference. Surface contact with the outer peripheral surface of the end.

Next, when a predetermined alternating current voltage is applied to the vibrator 1, the end of the vibrator 1 moves in an elliptical manner, and each divided piece 5a curves inward from the outside, and curves toward the end of the vibrator 1. Follow the movement. Looking at the movement of the tips of these divided pieces 5a,
The ring formed by the tips of the three divided pieces 5a follows the ends of the vibrator l and moves in an elliptical manner. During this time, each divided piece 5a of the rotor 5 maintains a state of surface contact with the vibrator 1, and rotates by receiving a driving force from the surface contact portion.

FIG. 3 is a sectional view of another embodiment of the invention.

In this embodiment, an output shaft 14 is provided, and the base of the output shaft 14 is coaxially and integrally connected to the bottom 5b of the rotor 5 formed in a cup shape. A midway portion of the output shaft 14 is rotatably supported by a cylindrical caning 16 via a bearing I5.

Also in this embodiment, the rotor 5 has a plurality of axial slits 10. ... are formed, and these slits 10.
The rotor 5 is divided into a plurality of divided pieces 5a, and these divided pieces 5a are elastically biased toward the inner diameter side by a coil spring 6 wound around the outer circumference of the rotor 5.
is in pressure contact with the outer peripheral surface of the vibrator I.
It is the same as the embodiment shown in FIGS. 1 and 2, and therefore, the operation when the vibration T-1 drives the rotor 5 is also as follows.
This is the same as in the embodiment of FIG.

In each of the above embodiments, f is wound around the outer periphery of the rotor 5.
The cocoil spring 6 may apply elasticity to each divided piece 5a toward the inner diameter side, or the divided pieces themselves may have spring properties, and the elasticity may cause the divided pieces 5a to elastically deform toward the inner diameter side.

<Effects of the Invention> According to the present invention, each divided piece of the rotor curves following the movement of the end of the vibrator to maintain surface contact with the outer peripheral surface of the vibrator. This allows the driving force of the vibrator to be transmitted to the rotor, resulting in high efficiency.

In addition, since the outer circumferential surface of the vibrator and the inner circumferential surface of the rotor are in surface contact over almost the entire circumference, the driving force of the vibrator is not concentrated locally but is dispersed over the entire circumference of the rotor. First, local wear on the rotor is eliminated, driving performance remains unchanged even after long-term use, and torque remains stable.

In addition, it has the advantage that it is easy to align the axes of the vibrator and rotor, and, like the conventional internal type, it can be miniaturized with an l-axis structure.

[Brief explanation of the drawing]

1 and 2 show one embodiment of the present invention; FIG. 1 is an exploded perspective view thereof, FIG. 2 is a sectional view, FIG. 3 is a sectional view of the second embodiment, and FIG. 4 is a circular FIG. 3 is a perspective view of a rod-shaped vibrator. 5 to 8 relate to conventional examples, FIG. 5 is a perspective view of the first conventional example, FIG. 6 is a perspective view of the second conventional example, FIG. 7 is a sectional view thereof, and FIG. is a sectional view of a third conventional example. l.Round rod-shaped vibrator, 5..Rotor, 5a..Divided piece,
6 coil spring (biasing means), 7... roller.

Claims (1)

[Claims] (1) Comprising a round rod-shaped vibrator and a cylindrical rotor fitted onto the end of the vibrator, the rotor having a plurality of axial slits formed at equal intervals in the circumferential direction. It is divided into a plurality of divided pieces, and each divided piece is fitted with a biasing means that biases each divided piece toward the inner diameter side so as to press each divided piece against the outer peripheral surface of the vibrator. An ultrasonic motor characterized by: