JPH04322178A - Piezoelectric motor - Google Patents

Abstract

PURPOSE:To provide a piezoelectric motor which obtains. reliable rotating force in both directions and easily enables adjustment of rotating velocity. CONSTITUTION:A piezoelectric motor comprises a rotatably supported rotating shaft 15, a driving force converting member 14 which is fitted to this rotating shaft 15 and conerts an external force based on vibration applied in the axial direction into divided forces for reversible rotation of the rotating shaft 15, a pair of piezoelectric elements 17, 17 which separately provided in both sides of the driving force converting member 14 to generate vibration in the axial direction of the rotating shaft 15 and a pressing mechanism 21 which selectively presses the one of the pair of piezoelectric elements 17, 17 with the driving force converting member 14.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small motor used in electronic equipment, and more particularly to a piezoelectric motor that rotates a rotor using a piezoelectric element.

0002

[Prior Art] Piezoelectric motors can obtain high torque at low rotation speeds compared to conventional electromagnetic motors, and also do not generate electromagnetic noise, so they are used for camera autofocus, etc. It's being used. The basic driving principle of such a piezoelectric motor is that a piezoelectric element that generates elliptical motion is used as a stator, and a rotor that is pressed against the stator generates rotational motion through frictional force. An example with such a configuration is shown in FIG. The piezoelectric motor shown in the figure is
It is a combination of a bolt tightening vibrator 1 that generates torsional vibration and a plurality of laminated piezoelectric elements 2. The combination of the movements of both produces an elliptical motion at the upper end of the laminated piezoelectric element 2, and the laminated piezoelectric element This generates rotational torque in the rotor 3 which is in pressure contact with the rotor 2. Note that the reference numeral 4 in the figure is a resonant metal block.

0003

[Problems to be Solved by the Invention] However, in the piezoelectric motor or the like having the conventional structure described above, in order to rotate the rotor 3 in any direction, a plurality of laminated piezoelectric elements 2 are required together with the bolt tightening vibrator 1. However, there were problems in that reliable bidirectional rotational force could not be obtained and it was very difficult to adjust the rotational speed. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a piezoelectric motor that can obtain reliable bidirectional rotational force and that can easily adjust the rotational speed.

0004

[Means for Solving the Problems] The structure of the present invention for achieving the above object is based on a rotatably supported rotary shaft and vibrations fixed to the rotary shaft and applied in the axial direction. A driving force converting member that converts external force into component forces in the forward and reverse rotational directions of the rotating shaft, and a driving force converting member that is placed spaced apart on both sides of this driving force converting member to generate vibrations in the axial direction of the rotating shaft. a pair of vibration generating members having a piezoelectric element, and one of the pair of vibration generating members and the driving force converting member select a forward rotation converting side, or the other of the vibration generating members and the driving force converting member select a reverse rotation converting side. The present invention is characterized in that it has a pressure contact mechanism section that brings the pressure contact into contact with each other.

[0005]

[Operation] The operation of the present invention having the above configuration will be explained. When one of the pair of vibration generating members placed apart on both sides of the driving force converting member is pressed against the forward rotation conversion side of the driving force converting member by the pressure contact mechanism, the vibration of the piezoelectric element converts the driving force. transmitted to the member. The driving force converting member to which this vibration is applied converts the external force based on this vibration into a component force in a direction that rotates the rotation shaft in one direction. This component force rotates the rotation shaft in one direction. Furthermore, when the other vibration generating member is pressed against the reverse rotation conversion side of the driving force converting member by the pressing mechanism, the external force based on the vibration applied from the piezoelectric element is applied to the rotation axis by the driving force converting member. is converted into a force that rotates in the opposite direction. As a result, the rotation shaft rotates in the opposite direction to that described above. By selectively press-contacting the vibration generating member having a pair of piezoelectric elements and the driving force converting member by the press-contact switching mechanism, a reliable bidirectional rotational force can be obtained and the rotation speed can be easily adjusted.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below with reference to the drawings. FIG. 1 is an external perspective view including a partial cross section of a piezoelectric motor as an example, and FIG. 2 is an exploded perspective view of the piezoelectric motor shown in FIG. Note that FIG. 2 only shows the components housed within the case. Piezoelectric motor 1 shown in FIGS. 1 and 2
0 includes vibration generating members 12, 12, a sliding member 13 that slides both vibration generating members 12, 12 while maintaining a constant interval, and a vibration generating member 12 held at a constant interval,
A driving force converting member 14 disposed between the driving force converting member 12, a rotating shaft 15 to which the driving force converting member is integrally attached, and a rotating shaft 15 fitted to both ends of the rotating shaft 15 to rotatably support the driving force converting member 14. It has bearings 16, 16 and a case 11 that supports these bearings 16, 16 at both ends.

The case 11 is made of duralumin or the like in a cylindrical shape, and has both end surfaces 11a, 11
A through hole 11 into which the bearings 16, 16 are press-fitted in the center of b.
c, 11c are formed, and an elongated hole 11e is formed in the upper center of the side wall surface 11d of this case 11 as shown. This elongated hole 11e is connected to a sliding member 13 whose details will be described later.
The length is set to restrict the range of movement of the

The vibration generating member 12 has a rotating shaft 1 at its center.
It has a cylindrical shape and has a common through hole 12a into which the holder 5 is slidably inserted. The vibration generating member 12 includes a piezoelectric element 17 that generates vibration in the axial direction of the rotating shaft 15, electrode members 18, 18 provided on both end surfaces of the piezoelectric element 17, and further provided on both sides of the piezoelectric element 17. It is formed by integrating two metal resonance members 19, 19. A pair of vibration generating members 12, 12 as described above are arranged slidably along the rotation shaft 15 with a constant interval maintained therebetween via the sliding member 13. Note that a power source (not shown) is connected to each of the electrode members 18, 18, and the driving force converting member 14 and the vibration generating member 1, details of which will be described later, are connected to each of the electrode members 18, 18.
When the vibration generating members 12 and 2 come into contact with each other, power is switched so that only the one vibration generating member 12 that is in contact with the vibration generating member 12 is supplied with electric power.

The sliding member 13 is a resonance member 19 on the side opposite to each other of the pair of vibration generating members 12, 12.
A connecting member 13a with both ends attached to the upper part of the diagram.
and a lever 13b screwed into the upper center of the connecting member 13a. In this embodiment, one end of the torsion coil spring 20 is attached to the upper part of the lever 13b, and when the lever 13b is moved to the vicinity of both ends of the elongated hole 11e, the vibration generating member 12,
12 and the driving force converting member 14 are brought into pressure contact. This sliding member 13 and torsion coil spring 20
This constitutes the pressure contact mechanism section 21. Note that the configuration of this pressure contact mechanism is not limited to the configuration shown above, and may include coil springs or other spring members,
The sliding member may be biased by a known actuator such as a solenoid or an air cylinder.

FIGS. 3A and 3B are a front view and a side view, respectively, showing details of the driving force converting member formed integrally with the rotation shaft. Driving force conversion member 1 shown in the figure
Reference numeral 4 is made of a metal plate, such as phosphor bronze, formed into a disk shape, and blades 14c to 14e and 14f to 14h are formed protruding from both end surfaces 14a and 14b at a predetermined angle α, respectively. It comes into contact with the vibration generating members 12, 12 through each blade group. In addition, each blade group is formed to be inclined in different directions,
The rotation shaft 15 is rotated in either direction depending on the direction of inclination.

Each blade 14c to 14e and 14
f to 14h are inclined at the predetermined angle α with respect to a plane orthogonal to the rotation axis 15, and are formed at equal angular intervals around the rotation axis 15. In this embodiment, three blades 14c to 14e and 14f to 14 are used.
h are formed at intervals of 120 degrees. With each blade group, an external force caused by vibration of the piezoelectric element 17 in one direction generates a component force that rotates the driving force converting member 14 in the opposite direction. The number and angle of the blades may be determined by appropriately considering the material, weight, etc. of the driving force converting member 14 itself.

The operation and effects of the piezoelectric motor having the above configuration will be explained with reference to FIGS. 4(A) to 4(C). FIGS. 4(A) to 4(C) are explanatory diagrams showing the operation of the driving force converting member and the vibration generating member that selectively abuts the driving force converting member. As shown in FIG. 2A, when the rotation shaft 15 is not rotated, the vibration generating members 12, 12 and the driving force converting members 14, 14 are separated from each other. In this state, since vibration in the axial direction of the rotation shaft 15 is not applied to the driving force conversion member 14, the rotation shaft 15 is stopped. A locking mechanism for holding both vibration generating members 12 and 12 in a separated state is not shown. When the sliding member 13 (not shown in the figure) is moved from this state to the right in the figure, the vibration generating member 12 on the left side in the figure and the driving force converting member 14 come into contact with each other via the blades 14c to 14e. In this state, the sliding member 13 is pressed by the torsion coil spring 20. At the same time as this contact is made, a voltage is applied to the electrode members 18, 18.

By applying this voltage, the piezoelectric element 17 has the following effects:
Vibrations are generated in the axial direction of the rotating shaft 15. The external force caused by this vibration generates a component force that causes the blades 14c to 14e, which are formed to be inclined at a predetermined angle α in one direction, to rotate the rotating shaft 15 in one direction. This blade 14c to 1
The rotation shaft 15 is rotationally driven in one direction by the component force generated by 4e. In this case, the rotational speed of the rotating shaft 15 can be easily adjusted by varying the inclination angle α of the blades 14c to 14e.

[0014]The rotation shaft 15 can be reversed as follows. Sliding member 13 (not shown in the figure)
When the vibration generating member 12 and the driving force converting member 14 on the right side in the figure are moved to the left in the figure, the blades 14c to 1
4e, and in this state, the driving force converting member 14 and the vibration generating member 12 are pressed together by the torsion coil spring 20. At the same time as this contact, the electrode member 18
, 18 are applied with voltage. By applying this voltage, vibration is generated in the piezoelectric element 17 in the axial direction of the rotating shaft 15. The external force caused by this vibration is applied to the blade 14f, which is formed to be inclined at a predetermined angle α in a direction different from that of the blade group.
14h generates a component force that rotates the rotating shaft 15 in the other direction. The rotating shaft 15 is driven in the reverse direction by the force generated by the blades 14f to 14h.

[0015] With the piezoelectric motor described in detail above, the rotation axis can be easily adjusted by simply selectively pressing one of the pair of piezoelectric elements onto the driving force converting member having blades formed on both end faces. It can be rotated forward and backward. Moreover, the blade formed in the driving force converting member can reliably generate a component force in the direction of rotating the rotation shaft, so that a good rotational state can be obtained. Furthermore, since the inclination angle of the blade can be easily varied, the rotational speed of the rotation shaft itself can also be easily adjusted.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but can be modified in various ways within the scope of its gist. In the above embodiment, the driving force conversion member was fixed in the axial direction and the vibration generating member itself was made to slide in the axial direction, but the vibration generating member itself was fixed in the axial direction and the driving force conversion The member and the rotation shaft may be moved in the axial direction. Even in the case of such a configuration, the same effects as in the above embodiment can be obtained.

[0017]

[Effects of the Invention] According to the present invention described in detail above, the pair of vibration generating members disposed on both sides are alternately pressed against the driving force converting member, thereby reliably rotating the rotating shaft in both directions. Therefore, it is possible to provide a piezoelectric motor whose rotational speed can be easily adjusted.

[Brief explanation of drawings]

FIG. 1 is an external perspective view including a partial cross section of a piezoelectric motor as an example.

FIG. 2 is an exploded perspective view of the piezoelectric motor shown in FIG. 1.

FIGS. 3A and 3B are a front view and a side view, respectively, showing details of a driving force converting member formed integrally with the rotation shaft.

FIG. 4 is an explanatory diagram showing the operation of a driving force converting member and a vibration generating member selectively abutted thereon.

FIG. 5 is a perspective view showing a schematic configuration of a conventional piezoelectric motor.

[Explanation of symbols]

12 Vibration generating member 14 Driving force conversion member 21 Pressure welding mechanism section

Claims (1)

[Claims] Claim 1: A rotary shaft that is rotatably supported, and an external force that is fixed to the rotary shaft and is based on vibrations applied in the axial direction, and that divides the external force in the forward and reverse rotation directions of the rotary shaft. a pair of vibration generating members having piezoelectric elements spaced apart from each other on both sides of the driving force converting member to generate vibration in the axial direction of the rotating shaft; and a pair of vibration generating members. A piezoelectric motor, comprising a pressure contact mechanism that selectively presses one of the forward rotation conversion side of the driving force conversion member or the other of the vibration generating member and the reverse rotation conversion side of the drive force conversion member. .