JP2992062B2 - Ultrasonic motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to an ultrasonic motor using a vibration generated in a stator as a driving source.

(Prior Art) Conventionally, an ultrasonic motor that rotates a rotor by using vibration energy generated in a stator is known. In this type of ultrasonic motor, vibration energy generated in the stator is transmitted to the rotor by frictional force, and the rotor rotates. An ultrasonic motor having such a configuration has been proposed in, for example, Japanese Patent Application Laid-Open No. 63-73887.

Hereinafter, a conventional ultrasonic motor will be described with reference to FIG.

An inner hole of a ring-shaped stator 2 is fitted to the base 1,
The inner peripheral side of the stator is fixed via the countersunk screw 3 so as not to vibrate. A ring-shaped piezoelectric ceramic 4 is adhered to one surface of the stator 2 so as to transmit vibration. A large number of protrusions 2a are formed on the surface of the stator 2.

By applying a pair of AC voltages having phases different from each other to the piezoelectric ceramics 4, the piezoelectric ceramics 4 expands and contracts,
Traveling wave vibration is generated in the stator 2.

The rotor 6 is constantly pressed against the stator 2 by the pressing force of the disc spring 7. A friction material 6 a is adhered to the rotor 6, and the friction material 6 a contacts the stator 2. Also, the disc spring 7
A rubber sheet 8 is sandwiched between the rotor and the rotor 6.

The disc spring 7 is held by a holder 10. The driving force of the rotor 6 is transmitted to the rotating shaft 12 through the disc spring 7 and the holder 10. The rotating shaft 12 is rotatably supported by a bearing 13 fixed to the base 1 and a bearing 9 fixed to the housing 5.

The pressing force of the disc spring 7 is adjusted by changing the thickness and the number of shims 15 inserted between the snap ring 14 and the bearing 13. The disc spring 7 urges the rotating shaft 12 through the holder portion 10 toward the housing 5 (upward in the figure). Therefore,
By removing the snap ring 14 and increasing the thickness and the number of shims 15, the holder 10 can be brought closer to the stator 2 to increase the pressing force. Conversely, by reducing the thickness and the number of shims 15, the holder 10 can be moved away from the stator 2 to reduce the pressing force.

(Problems to be Solved by the Invention) However, the conventional ultrasonic motor has a structure in which the rotating shaft 12 can move in the axial direction. Therefore, when an external force acts on the rotating shaft 12, the holder portion 10 moves, There is a problem that the pressing force acting between the rotor 6 and the stator 2 changes. Since the ultrasonic motor rotates the rotor 6 by the frictional force, when the pressure between the rotor 6 and the stator 2 changes, a predetermined driving force cannot be obtained from the motor,
The motor generates abnormal noise.

The present invention has been made to solve such a problem of the conventional apparatus, and has as its technical object to prevent external force applied to a rotating shaft from acting on a holder.

[Configuration of the invention]

(Means for Solving the Problems) The technical measures taken to achieve the above-described technical problems include a stator on which piezoelectric ceramics are fixed, a rotor rotated by a traveling wave generated on the stator, and a rotor. A disc spring having one end locked to the rotor and pressing the rotor against the stator, a base to which the stator is fixed,
The bearing fixed to the base has a stepped shape having a large-diameter portion and a small-diameter portion, and is fitted to the small-diameter portion so as to be locked to a stepped portion between the large-diameter portion and the small-diameter portion. A rotating shaft rotatably supported by the base via the bearing, and a non-rotatable and axially movable relative to the small-diameter portion of the rotating shaft; A holder that locks and supports the rotor so as to be relatively non-rotatable and relatively movable in the axial direction; a shim disposed between the bearing and the holder to adjust a pressing force of the disc spring; A regulating member fixed to the small-diameter portion and holding the bearing, the shim, and the holder between itself and the stepped portion is provided.

(Operation) According to the above-described technical means, the holder, the shim, and the bearing are held by the restricting member fixed to the rotating shaft, being locked to the step provided on the rotating shaft between the rotating shaft and the holder. Therefore, the external force applied to the rotating surface is received by the bearing and the base and does not act on the holder.

Further, according to the above-mentioned technical means, the pressing force of the disc spring can be easily adjusted by replacing the shim or increasing or decreasing the number of shims.

Further, since the pressing force between the rotor and the stator is kept stable, a predetermined driving force can be obtained from the motor. Also,
Generation of abnormal noise can also be prevented.

Hereinafter, preferred ultrasonic motors to which the present invention is applied will be described with reference to the accompanying drawings.

FIG. 1 is a sectional view illustrating a device according to a first embodiment of the present invention.

A housing 37 is fixed to the base 21. The housing 37 houses the stator 22 and the rotor 26.

An inner hole of a ring-shaped stator 22 fits into the base 21,
The inner peripheral side of the stator 22 is fixed via a countersunk screw 23 so as not to vibrate. A ring-shaped piezoelectric ceramic 24 is adhered to one surface of the stator 22 so as to transmit vibration. A number of protrusions 22a are formed on the surface of the stator 22.

By applying a pair of AC voltages having different phases to the piezoelectric ceramics 24, the piezoelectric ceramics 24 expands and contracts,
Traveling wave vibration is generated in the stator 22.

The rotor 26 is constantly pressed against the stator 22 by the pressure of the disc spring 27. A friction material 26a is bonded to the rotor 26, and the friction material 26a contacts the stator 22.

The disc spring 27 is held by the holder 30. The holder 30 is fixed to an end of the rotating shaft 32 and is fixed to the rotating shaft 32 by a nut 34 serving as a regulating member.

A serration (not shown) is formed between the rotor 26 and the holder 30 so that the rotor 26 and the holder 30 rotate integrally. The driving force of the rotor 26 is transmitted to the rotating shaft 32 through the holder 30. Further, the holder 30 can slide in the axial direction of the rotor 26 by this serration. The pressing force of the disc spring 27 is adjusted by changing the thickness of the shim 36 inserted between the holder 30 and the bearing 33, or by stacking a plurality of shims 36.

In this embodiment, a serration (not shown) is formed between the rotor 26 and the holder 30, but a double chamfer or the like may be formed.

The rotating shaft 32 has a stepped shape having a large diameter portion and a small diameter portion,
A stepped portion 32a is formed by the large-diameter portion and the small-diameter portion, and the shim 36 and the bearing 33 are interposed between the stepped portion 32a and the holder 30 so that the shim 36 and the bearing 33 are rotatable relative to the base 21 and axially Is immovably supported. Since the bearing 33 is fixed to the base 21, even if an external force acts on the rotating shaft 32, the applied external force is received by the bearing 33 and the base 21, and does not act on the holder 30 or the disc spring 27.

The second embodiment will be described below with reference to FIG. FIG. 2 is a sectional view of the second embodiment.

In the second embodiment, the end face 27a of the disc spring 27 and the rotor 26
A spring collar 28 is sandwiched between the two. The spring collar 28 is a metal ring, and the thickness between the end face 27a and the rotor 26 is constant over the entire circumference. Therefore, even if the flatness of the end face 27a of the disc spring 27 is somewhat poor, the disc spring 27 does not strongly press a part of the rotor 26, and the pressing force of the disc spring 27 is uniformly distributed in the circumferential direction of the rotor 26. I will be.

The spring collar 28 has a rotor around the circumference of the disc spring 27.
Since it is lifted from 26, the pressing force of the disc spring 27 can be increased until the disc spring 27 projects toward the rotor 26 side. Therefore, the range of adjusting the pressing force of the disc spring 27 is widened.

In the embodiment device described above, there is one bearing 33 that supports the rotating shafts 32 and 42. Therefore, the thickness of the ultrasonic motor can be reduced as compared with the case where the rotating shaft is supported by two bearings.

Also, since all the components of the ultrasonic motor are assembled on the base 21, the rotating shaft 32, the stator 22, the holder 30,
And it is easy to make the rotor 26 coaxial. Hence the stator
A uniform pressing force can be applied between the rotor 22 and the rotor 26, thereby preventing generation of abnormal noise and fluctuation of the driving force.

Further, since all the components of the ultrasonic motor are assembled on the base 21, the mechanical strength and the dimensional accuracy of the housing 37 may be low. Therefore, the housing 37 can be made thinner and lighter.

〔The invention's effect〕

According to the present invention, the pressing force of the disc spring can be easily adjusted by replacing the shim or increasing or decreasing the number of shims.

Further, according to the present invention, since the pressing force between the rotor and the stator is kept stable, a predetermined driving force can be obtained from the motor. Also, generation of abnormal noise can be prevented.

[Brief description of the drawings]

 FIG. 1 is a sectional view illustrating a first embodiment of the present invention. FIG. 2 is a sectional view depicting a second embodiment of the present invention. FIG. 3 is a sectional view illustrating a conventional device. 21 ... Base, 22 ... Stator, 23 ... Screw, 24 ... Piezoelectric ceramics, 26 ... Rotor, 27 ... Disc spring, 28 ... Spring collar, 30 ... Holder, 32 ... Rotating shaft, 33 … Bearing, 34… Nut, 36… Shim, 37… Housing, 41… Shim, 42… Rotating shaft.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akemi Okawa 2-1-1 Asahi-cho, Kariya-shi, Aichi Aisin Seiki Co., Ltd. (72) Inventor Shinji Sagara 1-333 Nitsuya, Kitamoto-shi, Saitama 2-325 Hydens (72) Inventor Tsuneji Ono Large character square 4641-12 Ageo-shi, Saitama Examiner Hiroshi Shimohara (56) References JP-A-2-303377 (JP, A) JP-A 4-222474 (JP, A) JP-A-63-73887 (JP, A) JP-A-2-41677 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H02N 2/00

Claims (1)

(57) [Claims] 1. A stator to which piezoelectric ceramics are fixed, a rotor rotated by a traveling wave generated on the stator, a disc spring having one end locked to the rotor to press the rotor against the stator, and the stator. A base fixed to the base, a bearing fixed to the base, and a stepped shape having a large diameter portion and a small diameter portion, wherein the small diameter portion relates to a stepped portion between the large diameter portion and the small diameter portion. A rotating shaft rotatably supported by the base via the bearing fitted so as to be stopped, fitted to the small diameter portion of the rotating shaft so as to be relatively non-rotatable and relatively movable in the axial direction; A holder that locks the other end of the disc spring and supports the rotor so as to be relatively non-rotatable and relatively movable in the axial direction, and is disposed between the bearing and the holder to adjust a pressing force of the disc spring. A shim; and the small diameter of the rotating shaft. Is secured to, said between said stepped portion bearing, ultrasonic motor, characterized in that a regulating member for sandwiching said shim and the holder.