JP2538672Y2 - Ultrasonic motor drive - Google Patents

Description

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

(Problems to be solved by the invention) However, since the rotor of the ultrasonic motor is rotated by the frictional force acting between the rotor and the stator,
When an external force acts on the rotor from the rotation shaft, the frictional force between the rotor and the stator changes, so that a predetermined driving force cannot be obtained from the motor or the motor generates abnormal noise.

For this reason, conventionally, when the motor is fixed to the gear mechanism, there has been a problem that the axis of the rotating shaft of the motor must be aligned with the axis of the input shaft of the gear mechanism with high accuracy.

The present invention has been made in order to solve such a problem of the conventional device, and a technical problem is to make the axis of the rotating shaft of the motor coincide with the axis of the input shaft of the gear mechanism. I do.

[Structure of device]

(Means for Solving the Problems) The technical means taken to achieve the above-mentioned technical problem includes a rotatable reed screw and a reed screw which meshes with the reed screw and rotates the reed screw to rotate the reed screw. A gear mechanism having a moving body that moves along the screw; and an ultrasonic motor linked to the gear mechanism for rotating the lead screw. The ultrasonic motor is rotatable on the base and the base. A rotary shaft integrally formed with the lead screw at a part extending to the outside of the ultrasonic motor, a stator supported by the base and having a piezoelectric element fixed thereto, and supported by a holder on the rotary shaft via a holder; And a housing fixed to the rotor and the base pressed into contact with the stator and accommodating the stator, the holder and the rotor in cooperation with the base. That is, it was configured.

(Operation) According to the above-described technical means, the rotating shaft of the ultrasonic motor is used as the input shaft of the gear mechanism. Therefore, the axis of the rotary shaft of the ultrasonic motor always coincides with the axis of the input shaft of the gear mechanism.

(Embodiment) Hereinafter, a preferred embodiment apparatus to which the present invention is applied will be described.

 FIG. 1 is a sectional view of an ultrasonic motor.

An inner hole of a ring-shaped stator 2 is fitted to the base 1 and is fixed via a countersunk screw 3 so that the inner peripheral side of the stator cannot be vibrated. 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.

The piezoelectric ceramics 4 is a known element for generating a traveling wave in the ultrasonic motor 100. When a pair of AC voltages having different phases are applied to the piezoelectric ceramics 4, the piezoelectric ceramics 4 expands and contracts, and 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 stabilizer 8 is provided between the rotor 6 and the disc spring 7 so that the pressing force of the disc spring 7 is uniformly applied to the entire circumferential surface of the rotor 6.

The stabilizer 8 of this embodiment is made of an iron material, and has a larger mass than the rotor 6 made of an aluminum material. Here, if the mass of the stabilizer 8 is made larger than the mass of the rotor 6, the vibration of the rotor 6 is less likely to be transmitted to the disc spring.

Further, it is desirable that the stabilizer 8 be made of a material having high rigidity. This is because if the rigidity of the stabilizer 8 is low, the vibration of the rotor 6 is absorbed.

A ring-shaped projection 8 a is formed on the outer peripheral edge of the stabilizer 8. The protrusion 8a is located inside the contact surface between the rotor 6 and the stator 2 and presses the rotor 6 down.
Since the height of the projection 8a is formed with a certain dimensional accuracy, the pressing force of the disc spring 7 is uniformly distributed along the circumference of the projection 8a.

The disc spring 7 is held by a holder 10. Rotor 6
Is transmitted to the rotating shaft 12 through the disc spring 7 and the holder 10. A lead screw 12a is formed integrally with the rotating shaft 12. The rotating shaft 12 is a bearing fixed to the base 1.
It is rotatably supported by the bearing 13 and the bearing 9 fixed to the housing 5.

The ultrasonic motor 100 having such a structure is incorporated in the gear mechanism 400 and the headrest 300
It can be used for moving up and down. FIG. 2 is a perspective view illustrating the gear mechanism 400.

The motor fixing panel 202 is welded to the seat frame 201. Ultrasonic motor 100 has screw 101 on panel 202,
Fixed by 102. One end 12b of the rotating shaft 12 is inserted into a through hole 202b penetrating the panel 202 and a through hole 201b penetrating the frame 201. Rotating shaft 12 with through hole 20
By inserting it into 2b and 201b, the position of the motor 100 is determined.

The frame 201 has a pair of through holes 201a and 201c. Panel 202 also has through holes 202a and 202c. The through hole 201a is opened at a position corresponding to the through hole 202a, and a stay 301 is inserted therein. The through hole 201c is opened at a position corresponding to the through hole 202c, and a stay 302 is inserted therein. Through holes 201a, 20
Bushes 202 and 203 for decoration are fixed to 1c.

A moving body 303 is fixed to the stays 301 and 302. A screw hole 303b is formed in the center of the moving body 303. The lead screw 12a is engaged with the screw hole 303b.
When the ultrasonic motor 100 rotates the lead screw 12a, the moving body 303 and the stays 301 and 302 move up and down, and the headrest 300 moves up and down.

In the present embodiment, the position of the ultrasonic motor 100 is determined by inserting the rotating shaft 12 into the through holes 202b and 201b. Further, in the present embodiment, the rotating shaft 12 and the lead screw 12a are integrally formed and are always coaxial. Therefore, even if the rotating shaft 12 rotates, no force acts between the rotating shaft 12 and the frames 201 and 202. As a result, since no external force acts on the rotor 6, a constant driving force is always obtained from the ultrasonic motor 100, and no abnormal noise is generated.

The structure of the ultrasonic motor 100 can be variously changed.
FIG. 3 shows an example in which the rotating shaft 12 is supported by one bearing 19. In this example, in order to support the rotating shaft 12 with one bearing 19, the bearing 20 fixed to the base 1 by tightening the screw 20 is a lead screw.
It is sandwiched between 12a and holder 10. The ultrasonic motor of FIG. 3 has the same structure as the ultrasonic motor 100 of FIG. 1 except that the support structure of the rotating shaft 12 is different. Therefore, detailed description is omitted by assigning the same reference numerals. In the configuration of FIG. 3, since the bearing 19 is a thrust bearing, it is resistant to a thrust load, the diameter of the bearing 19 can be reduced, and a small supporting mechanism is required.

[Effect of the invention]

According to the present invention, the rotating shaft of the ultrasonic motor and the input shaft of the gear mechanism are integrated. Therefore, the axis of the rotary shaft of the ultrasonic motor always coincides with the axis of the input shaft of the gear mechanism.
Therefore, even when the rotating shaft rotates, no external force acts on the rotor, a constant driving force is always obtained, and no abnormal noise is generated.

In addition, the outer diameter of the ultrasonic motor itself does not increase, and the ultrasonic motor can be made advantageous in terms of space in the radial direction. Further, the rotating shaft integrally formed with the lead screw is rotatably supported on the base on which the stator is supported, and the rotor is supported on the rotating shaft via a holder, and the stator, the rotor and the holder are fixed to the base. Since the housing is accommodated in the housing, the ultrasonic motor such as the stator, the holder, the rotor, and the housing can be assembled from one direction with reference to the rotating shaft supported by the base, and the gear mechanism is linked to the ultrasonic motor. Can be. Thereby, the assemblability of the gear mechanism and the ultrasonic motor can be greatly improved. In addition, by the assembly from one direction, the housing accommodating the stator, the holder, and the rotor becomes a single unit, whereby the number of parts is reduced, and the assemblability can be further improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of an ultrasonic motor according to a first embodiment of the present invention. FIG. 2 is a perspective view of a gear mechanism to which the ultrasonic motor shown in FIG. 1 is applied. FIG. 3 is a sectional view of the ultrasonic motor according to the first embodiment of the present invention. DESCRIPTION OF SYMBOLS 1 ... Base, 2 ... Stator, 3 ... Screw, 4 ... Piezoelectric ceramics, 6 ... Rotor, 7 ... Disc spring, 8 ... Stabilizer, 9 ... Bearing, 10 ... Holder, 12 ... …
Rotating shaft, 13 ... bearing, 19 ... bearing.

Claims (1)

(57) [Scope of request for utility model registration] A gear mechanism having a rotatable lead screw, a moving body which meshes with the lead screw and moves along the lead screw by rotation of the lead screw; and a linkage with the gear mechanism. An ultrasonic motor that rotates the lead screw, the ultrasonic motor being a base, the lead screw being rotatably supported by the base and extending partly outside the ultrasonic motor, and the lead screw being integrated with the ultrasonic motor. A molded rotating shaft, a stator supported by the base and having a piezoelectric element fixed thereto, a rotor supported by the rotating shaft via a holder and pressed against the stator, and the stator fixed to the base, the holder and the rotor An ultrasonic motor driving device, comprising a housing for accommodating the base in cooperation with the base.