JP3164906B2 - Ultrasonic actuator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic actuator for frictionally driving a moving body by ultrasonic vibration utilizing expansion and contraction of a piezoelectric element or an electrostrictive element.

[0002]

2. Description of the Related Art A traveling wave motor using a disk-shaped vibrator as shown in FIG. 2 has been known. A central shaft 10 is attached to the fixed member 1, and the piezoelectric element 3 is attached to the vibrating body 4.
Is provided. The protrusion 5 and the liner 8 are in pressure contact with each other by a spring 9 attached to the moving body 6. For example, JP-A-59-96881 and JP-A-60-17
Japanese Patent No. 4073 discloses such a structure.

[0003]

However, in the conventional structure, it is good to take the output from the gear 6a provided on the moving body 6, but in order to take out the output from the tip of the central shaft 10, the moving body 6 must be at the center. Since the structure is held by a screw, a spring, or the like attached to the tip of the shaft 10, there is a disadvantage that the output is difficult to be taken out from the tip of the center shaft 10.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an ultrasonic actuator having a structure for taking out an output from a front end of a central axis of a moving body in order to solve such a conventional drawback.

[0005]

In order to solve the above problems, the present invention has a structure in which two bearings are built in a moving body in an ultrasonic actuator. Further, it was as follows. Instead of two bearings, use two oil-impregnated bearings or slide bearings. The inner diameter of one oil-impregnated bearing is press-fit into the center shaft, the outer diameter is loosely fitted to the moving body, and the inner diameter of the other oil-impregnated bearing is the center shaft The fitting is made such that the outer diameter is press-fitted into the moving body, and a seat with little friction is provided as a thrust receiver for the pressing spring.

One is a ball bearing and the other is an oil-impregnated bearing or a slide bearing. Was press-fitted into the moving body. A tension spring is provided in the central axis of the fixed cylinder, in which the two magnets face the thrust receiver of the pressing spring with the same polarity, and the moving body is pressed against the vibrating body.

[0007]

In the ultrasonic motor constructed as described above, the moving body and the central shaft structure have rigidity even when the output is taken out from the center axis direction of the moving body.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, a fixed member 1 includes a vibration supporting member 2.
And a polarized piezoelectric element 3 having an electrode pattern portion
Is adhered and fixed to the lower surface of the vibrating body 4. The vibration supporting member 2 may be integral with the fixing member 1 or may be separate from the fixing member 1. The vibrating body 4 has a projection 5. The center of the moving body 6 has a cylindrical projection 7 in the axial direction, from which rotational output can be taken out. A ball bearing 11 is provided. The inner ring 11 a is loosely fitted in the center shaft 10, and the outer ring 11 b is press-fitted into the moving body 6.
Inner ring 1 of ball bearing 12 at the upper end of the inner diameter of moving body 6
2a is press-fitted to the center shaft, and the outer ring 12b is loosely fitted in the inner diameter of the moving body 6.

A pressure spring 9 is set in a loaded state between the upper ball bearing inner race 12a and the lower ball bearing inner race 11a. In addition, x mark shows press fitting. A liner 8 is fixed to the moving body 6 and the vibrating body 4
And the liner 8 of the moving body 6 are in pressurized contact by spring pressure. The center shaft 10 is fixedly supported by the fixing member 1. The vibrating body 4 is press-fitted and fixed to the center shaft 10 to be integrated. The moving body 6 is rotatably attached to the center shaft 10 via bearings 11 and 12.

A cylindrical housing 1 is provided on the outer periphery of the fixing member 1.
5 is fixed, and an end plate 16 is fixed to the upper end surface of the cylindrical housing 15. FIG. 3 shows an oil-impregnated bearing or slide bearings 17a and 17b instead of the two bearings 11 and 12 shown in FIG. 1. The inner diameter of the oil-impregnated bearing 17a is press-fitted into the central shaft, and the outer diameter is loosely fitted in the moving body 6, The inner diameter of the oil-impregnated bearing 17b is loosely fitted in the center shaft 10, the outer diameter is press-fitted into the moving body 6, and a seat 18 with little friction is provided as a thrust receiver for the pressure spring 9.

FIG. 4 shows a ball bearing 11 on one side and an oil-bearing bearing or a slide bearing 17 on the other side. The inner diameter of the oil-impregnated bearing 17 is press-fitted into the central shaft, the outer diameter is loosely fitted in the moving body 6, and the other ball is inserted. The inner ring of the bearing 11 was loosely fitted on the center shaft 10, and the outer ring was press-fitted into the moving body 6.

FIG. 5 shows an example in which two magnets 19 and 20 face the thrust receiver of the pressure spring with the same polarity.
FIG. 6 shows a gear 23 attached to the cylindrical projection 7 of the moving body 6. In addition, the bearing receiver 21 and the bearing receiver 2 are used for axially fixing the outer ring and the inner ring into which the bearings are press-fitted.
2 is provided.

FIG. 7 shows an example in which the output chip 24 is fixed to the cylindrical projection 7 of the moving body 6 by press fitting, screwing or the like. FIG.
Press-fits the output chip 25 into the cylindrical projection 7 of the moving body 6,
This is an example of fixing with screws or the like.

FIG. 9 shows a state in which the center axis is the cylindrical center axis 29, the ceiling of the cylindrical projection 7 of the moving body 6 is provided, the hooking pin 26 is fixed, and the inner ring is fixed below the cylindrical center axis 29 by fixing the bearing outer ring. The moving body 6 can be brought into pressure contact with the vibrating body 4 by fixing the hooking pin b27 to the hooking pin 26 and setting the tension spring 28 to the hooking pins 26 and 27. At this time, the outer peripheral portion of the cylindrical central shaft 29 and the inner diameter portion of the cylindrical projection 7 serve as journal bearings, and a structure having high rigidity for taking out output is provided.

FIG. 10 shows an example in which FIG. 9 is made more compact so that the diameter of the output shaft can be freely set. As an application of the ultrasonic actuator of the present invention, for example, if it is used for a motor of an electronic timepiece, it is not affected by magnetism, and it has a low torque and a high torque.
Since the holding torque is strong, there is a possibility that is not present in the related art, such as being hardly affected by disturbance. In addition, applications in the field of medical devices and the like, which were impossible in the past, are also possible, and an ultrasonic motor that operates in the body can be realized.

[0016]

As described above, the present invention has a structure in which two bearings are built in the moving body and a tension spring is incorporated in the center axis of the moving body, so that the direction of the center axis of the moving body is improved. Even when the output is extracted from the moving body, there is an effect that the moving body and the central shaft structure can maintain rigidity.

[Brief description of the drawings]

FIG. 1 is a sectional view of an ultrasonic actuator according to the present invention.

FIG. 2 is a sectional view of a conventional traveling wave type ultrasonic motor.

FIG. 3 is a sectional view of an embodiment of the present invention when an oil-impregnated bearing or a sliding bearing is used.

FIG. 4 is a sectional view of an embodiment of the present invention when a ball bearing and an oil-impregnated bearing or a slide bearing are used.

FIG. 5 is a sectional view of an embodiment of the present invention when a magnet is used for a thrust receiver.

FIG. 6 is a sectional view of an embodiment of the present invention with a gear and a bearing receiver.

FIG. 7 is a sectional view of an embodiment of the present invention with an output chip attached.

FIG. 8 is a sectional view of an embodiment of the present invention in which another output chip is mounted.

FIG. 9 is a sectional view of an embodiment of the present invention when a tension spring is used.

FIG. 10 is a cross-sectional view of an embodiment of the present invention when the extension spring is used to make it more compact.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixed member 2 Vibration support member 3 Piezoelectric element 4 Vibration body 5 Projection part 6 Moving body 7 Cylindrical projection 8 Liner 9 Spring 10 Center shaft 11, 12 Bearing 11a, 12a Bearing inner ring 11b 12b Bearing outer ring 15 Cylindrical housing 16 End plate 17 Oil-impregnated or sliding bearing 18 Seat 19, 20 Magnet 21, 22 Bearing receiver 23 Gear 24, 25 Output chip 26, 27 Hook pin 28 Tension spring 29 Cylindrical central axis

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02N 2/12

Claims (2)

(57) [Claims] And 1. A fixing member, and <br/> central shaft fixed to said fixing member has a piezoelectric element or electrostrictive element, said central shaft
A vibrating body which is fixed to rotatably <br/> mounted against the central axis, a moving body to the vibrating body and the pressure contact, the
An ultrasonic actuator having the center axis and the front
Two upper and lower bearings are provided between
The inner diameter of the bearing closer to the body is fixed to the central axis
And its outer diameter has a gap with the moving body,
Inner diameter of one bearing has a gap with the central axis
And its outer diameter is fixed to the moving body, and the two
An ultrasonic actuator, wherein a pressure spring is held between bearings . 2. A fixing member and a fixing member fixed to the fixing member.
A central axis having a piezoelectric element or an electrostrictive element;
And a rotatable body with respect to the central axis.
A moving body that is attached and comes into pressure contact with the vibrating body;
An ultrasonic actuator having the center axis and the front
Two upper and lower bearings are provided between
The inner diameter of the bearing closer to the body is pressed into the center shaft.
And the outer diameter of the moving body is loosely fitted.
The inner diameter of the bearing of
Both the outer diameters are press-fitted into the moving body,
Super sound characterized by holding a pressure spring between rings
Wave actuator.