JP2569545B2 - Piezoelectric vibration motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a piezoelectric vibration motor that can be used in a wide range of fields such as a lens driving device for a camera and electric components of an automobile.

[Prior art] A piezoelectric vibration motor that uses ultrasonic vibration generated by a piezoelectric element as a driving force source has advantages such as a simpler structure and faster response than a conventional motor using electromagnetic force. Research and development are under way (see, for example,
No. 0779).

FIG. 13 shows the structure of a conventional piezoelectric vibration motor. Reference numeral 1 denotes an annular driving plate, on the lower surface of which a piezoelectric body 2 is integrally joined and a support 4 provided on the bottom surface of a housing 5. It is supported by. A driven plate 3 is provided on the upper surface of the driving plate 1, and is pressed and adhered to the driving plate 1 by a spring member 6. When an AC voltage is applied to the piezoelectric body 2 to generate traveling wave vibration, the upper surface of the driving body 1 performs an elliptical motion, and the driven plate 3 which is in close contact with the driving plate 1 receiving this circumferential component rotates. Perform exercise. Thus, the rotation force can be taken out of the motor by the rotation output shaft 7 fixed to the center portion of the driven plate 3.

[Problems to be Solved by the Invention] By the way, in the conventional piezoelectric vibration motor, since the piezoelectric body 2 which is a vibration source is located directly below the driven plate 3, the driven plate 3 is brought into close contact with the driving plate 1. Has a drawback in that the pressing force acts in a direction that regulates the vibration of the piezoelectric body 2 and leads to a reduction in driving efficiency.

The present invention has been made in view of the above circumstances, and has as its object to provide a piezoelectric vibration motor having high driving efficiency.

[Means for Solving the Problems] The piezoelectric vibration motor of the present invention will be described with reference to FIG. 1. An annular driving plate (1) has an inner peripheral surface or an outer peripheral surface which is a contact surface (1).
1), the contact surface (11) is cut at equal intervals in the circumferential direction, the cuts are divided into a plurality of vibrating pieces (12), and a mass portion (the tip) of each vibrating piece (12) projects vertically. 13) On the peripheral surface of the drive plate (1) except for the contact surface (13), piezoelectric bodies (2a, 2b) having different polarities are alternately arranged in the circumferential direction along the base end of each vibrating piece (12). Means for applying an alternating current to these piezoelectric bodies is provided. On the protruding end face of each of the mass portions (13), a driven plate (3a,
3b) is pressed and contacted by the spring members (6a, 6b).

[Operation] When an AC voltage is applied to the piezoelectric body to generate traveling wave vibration, the same traveling wave vibration also occurs in the driving plate integrally joined thereto. Along with this, each of the vibrating bars undergoes torsional resonance, and the driven plate in contact with the mass portion at the end of the vibrating bar rotates by the circumferential component of the torsional vibration. In this way, the vibration of the piezoelectric body is converted into a rotary motion, and the rotational force is transmitted to the outside of the motor via the rotary output shaft connected to the driven plate.

[Effects of the Invention] According to the above configuration, since the piezoelectric body is provided on the peripheral surface of the drive plate except for the contact surface with the driven plate, the force pressing the driven plate against the drive plate is a piezoelectric body that is a vibration source. Therefore, the vibration of the piezoelectric body is not regulated, so that the driving efficiency of the motor can be improved. In addition, since the contact surface is formed by the vibrating reed having the mass portion, a large rotational force can be obtained by torsional resonating the vibrating reed. In addition, the above configuration allows easy lamination, and a large driving torque can be obtained by lamination.

EXAMPLES Hereinafter, the present invention will be described with reference to the illustrated examples.

In FIG. 1, a motor housing 5 is a hollow cylindrical body, and a rotation output shaft 7 is provided at the center of the housing. The rotary output shaft 7 is rotatably supported by bearings 8a and 8b provided on upper and lower housing walls, and one end of the rotary output shaft 7 protrudes out of the housing and is connected to a driven body (not shown).

An annular driving plate 1 is disposed around the rotary output shaft 7 in the housing 5. The driving plate 1 has an inner peripheral end portion that is thick and protrudes vertically, and each protruding end surface is a contact surface 11. . The driven plates 3a and 3b are brought into contact with these contact surfaces 11, respectively.

FIG. 2 shows the details of the driving plate 1 and the driven plates 3a and 3b.
In the figure, the drive plate 1 is formed by cutting the inner peripheral portion at equal intervals, and the cuts are used as a plurality of vibrating bars 12. Then
These vibrating reeds 12 become mass portions 13 whose tips protrude in the radial direction (FIG. 3). The upper and lower end faces of each mass portion 13 constitute the contact surface 11.

Annular piezoelectric plates 2a and 2b are joined to the upper and lower surfaces of the outer peripheral portion of the driving plate 1 along the base end of each vibrating piece 12, and these piezoelectric plates 2a and 2b are alternately arranged at equal intervals in the circumferential direction. The polarization directions are different. At this time, the upper and lower piezoelectric plates 2a and 2b are bonded so as to be shifted so that the polarization positions have a phase difference of 90 ° (FIG. 4). Annular electrodes 21a and 21b are joined to the piezoelectric plates 2a and 2b, respectively.These are connected to an AC power source that outputs 90 ° phase-shifted outputs via lead wires.
Connected to 10a, 10b. The driving plate 1 is grounded as a common electrode.

Each of the driven plates 3a and 3b in contact with the driving plate 1 is formed in an annular shape, and a plurality of circumferential portions are fixed to the tip ends of the plate springs 6a and 6b having support legs extending radially. The above leaf springs 6a, 6b
Are provided with oblong mounting holes 61a and 61b, respectively, at the center. Then, the mounting holes 61a, 61b are fitted into the oblong mounting portion of the rotary output shaft 7 while the driving plate 1 is sandwiched between the driven plates 3a, 3b from above and below.

At this time, the lower leaf spring 6b is supported by the receiving flange 71 of the rotary output shaft 7, while the upper leaf spring 6a is held down by an adjusting nut 9 screwed into a screw portion on the outer periphery of the rotary output shaft 7. Thus, the contact pressure between the drive plate 1 and the driven plates 3a, 3b can be adjusted by rotating the adjusting nut 9.

The outer peripheral end of the drive plate 1 is brought into contact with a cushion member 51 provided on the inner peripheral wall of the housing 5 to position the same and prevent rotation.

When a sine wave voltage having a phase shift of 90 ° is applied to the piezoelectric bodies 2a and 2b, a traveling wave vibration as shown by a dashed line in FIG. (1) and (2) in the figure show the temporal transition of the traveling wave vibration. Accordingly, the vibrating reed 12 formed on the inner peripheral portion of the driving plate 1 performs torsional vibration having a phase shifted from the traveling wave by 180 ° (arrow in FIG. 5). The resonance frequency of the torsional vibration is determined by the elastic coefficient, the cross-sectional shape, and the moment of inertia of the mass portion 13 of the vibrating reed 12, and by appropriately setting these, the vibrating reed 12
Greatly resonates. The vibration displacement of the mass portion 13 is indicated by a vertical line along the wavy line in FIG.

Thus, the upper and lower ends of the mass portion 13 periodically come into contact with the upper and lower driven plates 3a, 3b, and are pressed and rotated in the direction of the arrow in the drawing by the circumferential component of the torsional vibration.

According to the above structure, the pressing force for bringing the driving plate 1 and the driven plates 3a and 3b into close contact with each other is not directly applied to the piezoelectric members 2a and 2b serving as the driving sources, so that the vibration of the piezoelectric members is not restricted and the driving efficiency is improved. I can do it. Further, since the contact surface 11 is constituted by the vibrating reeds 12 provided with the mass portions 13, and these vibrating reeds 12 are torsionally resonated, a larger rotational force can be obtained.

6 and 7 show another embodiment of the present invention. In FIG. 6, a plurality of driving plates 1a and 1b are provided around the rotation output shaft 7.
And driven plates 3a, 3b, 3c are alternately arranged on the inner peripheral portions of the driving plates 1a, 1b with the driving plates 1a, 1b interposed therebetween. The driven plates 3a and 3c are sandwiched between leaf springs 6a and 6b,
By adjusting the adjusting nut 9 provided on the outer peripheral portion, the pressing force of the driving plates 1a, 1b and the driven plates 3a, 3b, 3c can be adjusted. FIG. 7 shows a partially exploded perspective view of this embodiment. By thus forming the driving plate and the driven plate in a multi-plate configuration, it is possible to obtain a larger rotation output.

In this embodiment, the vibrating reed 12 has no apparent beam portion, and the mass portion 13 vibrates torsionally around its center.

As shown in FIG. 8, the configuration may be such that only the upper surfaces of the driven plate 3 and the driving plate 1 are in contact with each other. In the figure, the drive plate 1 disposed around the rotary output shaft 7 has an inner peripheral end portion that is thick and protrudes upward, and this protruding end surface serves as a contact surface 11 with the driven plate 3 and the contact surface 11. Are cut at equal intervals in the circumferential direction to form a resonator element 12 having a mass portion 13 at the tip. (9th
Figure). The drive plate 1 has an outer peripheral portion supported by a cushion member 51 provided on the bottom surface and the inner peripheral surface of the housing 5.

According to such a structure, the motor can be formed into a flat shape, which is advantageous when the installation space for the motor is limited.

The vibrating piece 12 may have a shape shown in FIGS. 10 to 11. In other words, the former adjusts the mass by circling the mass 13 at the center.
It is possible to change and adjust the mass while keeping the amount of protrusion in the vertical direction constant. In the latter case, semicircular grooves are formed on both side surfaces of the resonator element 12, and according to such a shape, torsional vibration can be easily generated.

The contact surface 11 may be provided on an outer peripheral portion of the driving plate 1. No.
In FIG. 12, an annular driving plate 1 is provided around the rotary output shaft 7.
a, 1b are arranged, and the driving plates 1a, 1b are made thicker at the outer peripheral end and protruded up and down to make contact surfaces 11 with the driven plates 3a, 3b, 3c.
The contact surface 11 is cut at equal intervals in the circumferential direction to form a number of vibrators. Annular piezoelectric plates 2a and 2b are joined to upper and lower surfaces of inner peripheral portions of the driving plates 1a and 1b, and inner peripheral ends of the driving plates 1a and 1b are connected to a cushion member 51 provided between the driving plates 1a and 1b and the rotary output shaft 7. It has been abutted.

The drive plates 1a and 1b have bar-shaped stoppers 14 erected at a plurality of locations on the outer peripheral surface, and the tips of the respective stoppers are inserted into locking holes 52 provided in the side wall of the housing 5 facing the same. The locking hole 52 is in the shape of a long hole extending in the vertical direction, so that the driving plate 1 can vertically vibrate and is prevented from rotating.

According to such a structure, processing of the contact surface 11 is easy,
Since a relatively expensive piezoelectric body can be made smaller, the cost can be reduced.

[Brief description of the drawings]

1 to 5 show an embodiment of the present invention, FIG. 1 is an overall sectional view of a piezoelectric vibration motor, FIG. 2 is a partially exploded perspective view,
FIG. 3 is an enlarged view of a main part, FIG. 4 is a perspective view of a driving plate, FIG. 5 is an operation explanatory view, and FIGS. 6 and 7 show a second embodiment of the present invention. 7 is an overall sectional view, FIG. 7 is a partially exploded perspective view, and FIGS. 8 to 9 show a third embodiment of the present invention.
8 is an overall sectional view, FIG. 9 is an enlarged view of a main part, and FIG.
FIG. 11 and FIG. 11 are enlarged views of essential parts showing fourth and fifth embodiments of the present invention, FIG. 12 is an overall sectional view showing a sixth embodiment of the present invention, and FIG. It is the whole sectional view shown. 1, 1a, 1b ... driving plate 11 ... contact surface 2, 2a, 2b ... piezoelectric plate (piezoelectric body) 3, 3a, 3b, 3c ... driven plate 6, 6a, 6b ... leaf spring 7 ... Rotary output shaft 10a, 10b …… AC power supply

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-43082 (JP, A) JP-A-61-277384 (JP, A) JP-A-62-196085 (JP, A)

Claims (2)

(57) [Claims] The drive plate is formed in an annular shape and its inner peripheral surface or outer peripheral surface is formed as a contact surface with a driven plate. The contact surface is cut at equal intervals in the circumferential direction, and the cuts are divided into a plurality of vibrating pieces. And, as a mass part projecting up and down at the tip of each vibrating piece, the driven plate provided on the rotary output shaft is brought into elastic contact with the protruding end face of each mass part, and of the drive plate excluding the contact surface. Piezoelectric vibrating motor characterized in that piezoelectric bodies having different polarities are alternately arranged in the circumferential direction along the base end of each vibrating piece on the peripheral surface, and means for applying an AC voltage to these piezoelectric bodies is provided. . 2. The piezoelectric vibration motor according to claim 1, wherein said piezoelectric vibration motor has a laminated structure in which said driving plate and said driven plate are laminated in a plurality of stages.