JPS63310379A - Ultrasonic motor provided with electromagnetic clutch - Google Patents

Abstract

PURPOSE:To simplify the structure and to reduce the size and the weight, by placing an annular electromagnet inside a stator and employing a return spring at the portion of an electromagnetic clutch as a spring means. CONSTITUTION:A casing 1 for a ultrasonic motor M comprises two portions 1a, 1b, and a disc rotor 4 is arranged at the intermediate section of an output shaft 2. A stator member 5 is mounted and secured through a piezoelectric element 6 to the inner face of bottom wall at the other portion 1b of the casing 1, and a friction member 8 is applied onto the inner face of the rotor 4 facing the free end face of an annular projection 5a of the stator member 5. An annu lar yoke 11 containing a coil 10 is arranged at the free end of boss 9 while surrounding an output shaft 2 and facing the rotor 4. Furthermore, a disc 13 is fitted over the output shaft 2 and a diaphragm spring 15 is held by the disc 13. Consequently, the spring 15 energizes the rotor 4 continuously in the direction of separating the rotor 4 from the stator member 5, and pressure contacts therewith so that desired holding torque is produced through excitation of the coil 10.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an ultrasonic motor incorporating an electromagnetic clutch.

<Prior art> For example, as disclosed in Japanese Patent Application Laid-Open No. 61-277380, a traveling wave that moves with time is generated in a stator in which piezoelectric ceramics are attached to an elastic body, and a rotor is brought into face-to-face contact with the stator. Various types of ultrasonic motors have been proposed, such as a traveling wave type rotating ultrasonic motor. Such ultrasonic motors can obtain high torque at low speeds, have good responsiveness because the inertia matrix of the rotating body is small, and have a large holding torque when stationary, so they can prevent reverse rotation against external forces without a reduction gear. It has various features, such as being lightweight and compact due to its simple structure.

However, depending on the application, the drawback may be that the holding torque at rest is large. For example, the patent application
Assuming that such an ultrasonic motor is to be applied as an actuator for a constant-speed running device disclosed in Publication No. 291941, etc., if you want to cancel the constant-speed running state, you must quickly apply the throttle. If the holding torque of the ultrasonic motor when it is at rest acts as a resistance, there will be an inconvenience that the throttle operation at the time of release will be inhibited.

<Problems to be Solved by the Invention> Therefore, it is necessary to separately attach a disconnection device, and therefore, the problem arises that the small size and light weight of the ultrasonic motor are not fully utilized.

In view of these problems in the prior art, the main object of the present invention is to provide an improved ultrasonic motor equipped with an electromagnetic clutch so that the output end is free when stopped. .

Means for Solving the Problems> According to the present invention, the present invention provides a stator made of an annular elastic body having an electro-mechanical transducer, and a stator that is rotatably supported and that has an axial direction of the stator. a rotor in contact with an end surface; a spring means for constantly biasing the rotor in either a direction toward the stator or a direction away from the stator; and an electromagnet selectively biased toward the stator or away from the stator, the electromagnet being received within the inner periphery of the stator and biasing the rotor This is achieved by providing an ultrasonic motor with an electromagnetic clutch characterized by comprising annular electromagnets facing each other with their axial end faces.

<Operation> By doing this, not only is the structure compact because the electromagnet is received inside the annular stator, but also the rotor can be attached to the stator simply by using the return spring of the electromagnetic clutch as a spring means. Since a spring means for pressing is not required, it is possible to simplify the structure and make it smaller and lighter.

<Embodiments> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows an ultrasonic motor M constructed according to the present invention. The casing 1 of this ultrasonic motor M has two parts 1a and 1b. supported, and the free end of the output shaft 2 protrudes from a hole 1d formed in the axial end wall of the other portion 1b,
It is also pivotally supported in the chain hole 1d via a bearing 3b. The output shaft 2 is positioned in the axial direction by a pair of snap rings 2a fitted with a bearing 3b on the free end side in between. A disk-shaped rotor 4 is loosely fitted into an intermediate portion of the output shaft 2 located inside the casing 1 so as to be movable in the axial direction.

On the inner surface of the bottom wall of the other portion 1b of the casing 1, a stator member 5 having an annular convex portion 5a on its outer periphery is placed via a piezoelectric element 6 having an annular two-layer structure. This stator member 5 is integrally fixed to the other portion 1b with a synthetic resin screw 7, sandwiching a piezoelectric element 6 therebetween.
The annular convex portion 5a is provided with a plurality of slits 5b as is well known. Further, the annular convex portion 5a of the stator member 5
A wear material 8 made of a suitable material is adhered to the inner surface of the rotor 4 facing the free end surface of the rotor 4 .

A boss 9 that extends inward in the axial direction and surrounds the output shaft 2 is provided on the inner surface of the bottom wall of the other portion 1b so as to be continuous with the hole 1d. A ring-shaped yoke 11 containing a coil 10 is provided at the free end of the boss 9 so as to surround the output shaft 2 and not be in contact with the output shaft 2. The axially open end (upper side in FIG. 1) of the yoke 11 is connected to the rotor 4.
I am confronting my inner self. The yoke 11 and the coil 10 form an electromagnet.

A two-chamfered portion 12 is formed in a portion of the output shaft 2 above the rotor 4, and a disk 13 is fitted into the portion so as to rotate integrally with the output shaft 2. This disk 1
3 is prevented from being handled by a snap ring 14 interposed on the output shaft 2.

A diaphragm spring 15 is provided between the disk 13 and the rotor 4.
is inserted. The diaphragm spring 15 has its outer circumference fixed to the rotor 4 and its inner circumference fixed to the disc 13, respectively, and constantly biases the 1° rotor 4 in a direction away from the stator member 5. There is. In addition, the disk 13 has a hole 16.
is drilled, and the protrusion 17 provided on the rotor 4 is inserted into this hole 1.
6, so that the disk 13 can rotate together with the rotor 4.

Next, the operation of this embodiment will be explained.When the coil 10 is in a non-excited state, the rotor 4 is separated from the annular convex portion 5a of the stator member 5 due to the biasing force of the diaphragm spring 15. Therefore, since the output shaft 2 is only connected to the rotor 4 via the disc 13, it can be freely rotated by external force.

Next, when the coil 10 is excited, the rotor 4 is attracted and pressed against the axial end surface of the annular convex portion 5a of the stator member 5 via the friction material 8 against the spring force of the diaphragm spring 15. Therefore, in this case, even if an external force is applied to the output shaft 2, the desired holding torque will be generated. Further, at this time, the end face of the yoke 11 and the inner surface of the rotor 4 are not in contact with each other, and if the piezoelectric element 6 is driven in this state based on the principle of an ultrasonic motor, the output shaft 2 is rotationally driven via the rotor 4. The Rukoto.

In this embodiment, the rotor 4 is loosely fitted to the output shaft 2 so as to be rotatable, but the output shaft 2 and the rotor 4 are spline-coupled so that they rotate integrally with each other and can slide in the axial direction. A structure that allows for free movement is also possible, in which case,
The hole 16 in the disk 13 and the protrusion 17 in the rotor 4 can be omitted.

Further, the application of the present invention is not limited to the actuator of a constant speed cruise control device, but can be applied to all kinds of applications, such as a door lock actuator.

<Effects of the Invention> As described above, according to the present invention, an ultrasonic motor with an electromagnetic clutch can be configured compactly, and the effects are extremely large in expanding the uses of the ultrasonic motor.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing a preferred embodiment of an ultrasonic motor with an electromagnetic clutch according to the present invention. 1...Casing 1a, 1b...Part 1C・
...Recessed part 1d...Hole 2...Output shaft
2a...Snap ring 3a, 3b...Bearing
4...Rotor 5...Stator member 5a...
Annular convex portion 5b...Slit 6...Piezoelectric element 7
...Screw 8...Friction material 9...Boss
10...Coil 11...Yoke
12...Two-chamfered part 13...Disc plate 14.
... Snap ring 15 ... Diaphragm spring 16 ... Hole 17 ... Allowed when protruding
Patent attorney representing Mitsuka Denki Seisakusho Co., Ltd.
Yo Oshima - Figure 1

Claims (1)

[Scope of Claims] A stator made of an annular elastic body having an electro-mechanical transducer; a rotor rotatably supported and in contact with an axial end surface of the stator; and a spring means that constantly biases the rotor in either one of the directions toward the stator and the direction away from the stator against the spring force of the spring means. an electromagnet that selectively biases one of the magnets toward the other, and the electromagnet is an annular electromagnet that is received within the inner circumference of the stator and faces the rotor with an axial end face. An ultrasonic motor with an electromagnetic clutch featuring: