JPH0678569A - Ultrasonic actuator - Google Patents

Abstract

PURPOSE:To obtain a structure having rigidity to produce an output from a moving body in an ultrasonic motor. CONSTITUTION:Two bearings 11, 12 are contained in a moving body 6, a pressurizing spring 9 is held therebetween, and an inner race 12a of the one bearing 12 is press-fitted in a central shaft 10 and an outer race 12b is clearance fitted in the body 6. An inner race 11a of the other bearing 11 is clearance fitted in the shaft 10, and an outer race 11b is press-fitted in the body 6.

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 / contraction motion of a piezoelectric element or an electrostrictive element.

[0002]

2. Description of the Related Art Conventionally, a traveling wave type motor using a disc type vibrator as shown in FIG. 2 has been known. The 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, the output from the gear 6a provided on the moving body 6 is good, but in order to take the output from the tip portion of the central shaft 10, the moving body 6 is the center. Since the structure is held by screws, springs, etc. attached to the tip of the shaft 10, there is a drawback that the output is difficult to take out from the tip of the central shaft 10.

SUMMARY OF THE INVENTION In order to solve the conventional drawbacks described above, an object of the present invention is to obtain an ultrasonic actuator having a structure in which an output is taken out from the tip of the central axis of a moving body.

[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, the following was done. Instead of two bearings, use two oil-impregnated bearings or sliding bearings. One oil-impregnated bearing has an inner diameter press-fitted into the center shaft, the outer diameter fits into the moving body, and the other oil-impregnated bearing has an inner diameter. With a clearance fit, the outer diameter was press-fitted into the moving body, and a seat with less friction was provided as the thrust receiver of the pressure spring.

One is a ball bearing and the other is an oil-impregnated bearing, or a sliding bearing. The inner diameter of the oil-impregnated bearing is press-fitted into the central shaft, the outer ring is loosely fitted to the moving body, and the inner ring of the ball bearing is loosely fitted to the central shaft. Is configured to be pressed into a moving body. A tension spring is provided in the center axis of the cylinder fixed to face the two magnets facing each other with the same pole to the thrust receiver of the pressure spring, and the movable body is pressed against the vibrating body.

[0007]

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

[0008]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, a vibration support member 2 is attached to the fixed member 1.
And a polarized piezoelectric element 3 having an electrode pattern portion
Are bonded and fixed to the lower surface of the vibrating body 4. The vibration supporting member 2 may be integrated with the fixed member 1 or may be a separate member. 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 the rotational output can be taken out, and at the lower end of the inner diameter of the moving body 6, There is a ball bearing 11, the inner ring 11a of which is closely fitted to the central shaft 10 and the outer ring 11b of which is press-fitted to 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 into the central shaft, and the outer ring 12b is loosely fitted to the inner diameter of the moving body 6.

A pressure spring 9 is set between the upper end ball bearing inner ring 12a and the lower end ball bearing inner ring 11a in a loaded state. In addition, the symbol x indicates press fitting. The liner 8 is fixed to the moving body 6 and
The protrusion 5 and the liner 8 of the moving body 6 are in pressure contact with each other by the spring pressure. The central shaft 10 is fixedly supported by the fixed member 1. The vibrating body 4 is press-fitted and fixed to the central shaft 10 to be integrated. The movable body 6 is rotatably attached to the central 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 oil-impregnated bearings or sliding bearings 17a and 17b in place 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 into the moving body 6, The oil-impregnated bearing 17b has a clearance fit to the central shaft 10, the outer diameter is press-fitted to the moving body 6, and a seat 18 having less friction is provided as a thrust receiver of the pressure spring 9.

In FIG. 4, one is a ball bearing 11 and the other is an oil-impregnated bearing, or a slide bearing 17, 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 The inner ring of the bearing 11 was fitted in the central shaft 10 with a clearance, and the outer ring was press-fitted into the moving body 6.

FIG. 5 shows an example in which two magnets 19 and 20 are opposed to each other with the same pole on the thrust receiver of the pressure spring.
In FIG. 6, the gear 23 is attached to the cylindrical protrusion 7 of the moving body 6. Further, the bearing holder 21 and the bearing holder 2 are used to fix the outer ring and the inner ring in which the bearings are press-fitted in the axial direction.
This is an example including 2.

FIG. 7 shows an example in which the output tip 24 is press-fitted into the cylindrical projection 7 of the moving body 6 and fixed by screwing or the like. Figure 8
Is press-fitting the output tip 25 into the cylindrical protrusion 7 of the moving body 6,
This is an example of fixing with screws or the like.

In FIG. 9, the central axis is the cylindrical central axis 29, the ceiling portion of the cylindrical projection 7 of the moving body 6 is provided, the hooking pin 26 is fixed, and the bearing outer ring is fixed to the inner ring below the cylindrical central axis 29. By fixing the hooking pin b27 to and the tension spring 28 is set on the hooking pins 26 and 27, the moving body 6 can be brought into pressure contact with the vibrating body 4. At this time, the outer shape of the cylindrical center shaft 29 and the inner diameter of the cylindrical protrusion 7 serve as journal bearings, and the structure has high rigidity for taking out the output.

FIG. 10 shows an example in which FIG. 9 is more compactly arranged and the diameter of the output shaft can be freely set. As an application of the ultrasonic actuator of the present invention, for example, when it is used in a motor of an electronic timepiece, it is not affected by magnetism, and because of low torque and high torque, reduction of the number of gear trains
Since the holding torque is strong, there is a possibility that it will not be affected by disturbance, which is not possible in the past. In addition, it can be applied in the field of medical devices and the like, which has been impossible in the past, and an ultrasonic motor that operates inside the body can also 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 central axis of the cylinder. Even when the output is taken out from, the moving body and the central shaft structure have the effect of maintaining rigidity.

[Brief description of drawings]

FIG. 1 is a sectional view of an ultrasonic actuator of 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 sliding bearing are used.

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

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

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

FIG. 8 is a cross-sectional view of an embodiment of the present invention with another output chip attached.

FIG. 9 is a cross-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 it is made more compact by using a tension spring.

[Explanation of symbols]

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

Claims (1)

[Claims] 1. A disc-shaped fixing member, a central axis attached to a central portion of the fixing member, and a piezoelectric element or an electrostrictive element attached to the central axis and provided on a lower surface of the fixing element. A disc-shaped vibrating body installed on a vibration supporting member provided on the upper surface of the fixed member, and the vibrating body via a liner attached to the central axis and provided on an outer peripheral portion of the lower surface. It is composed of a cylindrical kana-shaped moving body installed on a protrusion provided on the outer peripheral part of the surface, and two bearings are built in the inside of the moving body and pressure is applied between the two bearings. The inner ring of the one bearing that holds the spring and is provided in the lower part of the moving body is loosely fitted to the central shaft, the outer ring is press-fitted into the moving body, and the inner ring of the other bearing is the center. When pressed into the shaft The ultrasonic actuator is characterized in that the outer ring is closely fitted to the moving body so that the liner and the protrusion come into pressure contact with each other.