JPS63262069A - Piezoelectric vibration motor - Google Patents

Abstract

PURPOSE:To easily laminate and to increase the driving torque of a piezoelectric vibration motor by providing a piezoelectric unit on the periphery of a driving plate except the contacting surface with a driven plate. CONSTITUTION:A motor housing 5 is formed of a hollow cylinder, and a rotary output shaft 7 is provided at its center. The shaft 7 is rotatably supported by bearings 8a, 8b, and connected to a driven unit. An annular drive plate 1 is disposed around the shaft 7, and contacting surfaces 11 projected upward and downward with the peripheral end as a thickness are provided. Driven plates 3a, 3b are contacted with the surfaces 11. Annular piezoelectric plates 2a, 2b are bonded along the base ends of vibration pieces 12 to the upper and lower surfaces of the outer periphery of the plate 1. Thus, when an AC voltage is applied to the plates 2a, 2b to generate a traveling wave vibration, Similar vibration occurs at the plate 1 integral therewith. Thus, the parts of the surfaces 11 are elliptically moved to obtain a rotary force from the shaft 7 coupled to the plates 3a, 3b.

Description

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

[Prior Art] Piezoelectric vibration motors, which use ultrasonic vibrations from piezoelectric elements as a driving force source, have advantages such as a simpler structure and faster response than conventional motors that use electromagnetic force, and have been put into practical use in recent years. Research and development is progressing toward
No. 00779).

FIG. 13 shows the structure of a conventional piezoelectric vibrator. Reference numeral 1 denotes an annular driving plate, and a piezoelectric body 2 is integrally joined to the lower surface of the drive plate, and a support provided on the bottom of the housing 5. It is supported by body 4. A driven plate 3 is disposed on the upper surface of the driving plate 1, and is pressed into close contact with 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 receiving this circumferential component, the driven plate 3 in close contact with the driving plate 1 moves. Perform a rotational movement. Thus, the rotational force can be extracted to the outside of the motor by the rotational output shaft 7 fixed to the center of the driven plate 3.

[Problems to be Solved by the Invention] By the way, in the conventional piezoelectric vibration motor described above, since the piezoelectric body 2, which is a vibration source, is located directly below the driven plate 3, the driven plate 3
There is a drawback that the pressing force for bringing the piezoelectric body 2 into close contact with the drive plate acts in a direction that restricts the vibration of the piezoelectric body 2, leading to a decrease in drive efficiency.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a piezoelectric vibration motor with high drive efficiency.

[Means for Solving the Problems] To explain the piezoelectric vibration motor of the present invention with reference to FIG. 1, an annular drive plate (1) has an inner or outer peripheral surface with a contact surface < 1
．． ]-), and piezoelectric bodies (2a, 2b) having different polarities are arranged alternately in the circumferential direction along the base end of each vibrating piece on the circumferential surface of the drive plate (1) excluding the contact surface. It has means for applying alternating current to these piezoelectric bodies. Driven plates (3a, 3b) provided on the rotational output shaft <7> are pressed into contact with the contact surface (11) by spring members (6a, 6b).

[Operation] When an alternating current voltage is applied to the piezoelectric body to generate traveling wave vibration, a similar traveling wave vibration is also generated in the drive plate that is integrally joined to the piezoelectric body. Accompanying this, each part of the contact surface performs an elliptical motion, and the driven plate in contact with the contact surface rotates due to the circumferential component of the elliptical motion. In this way, the vibration of the piezoelectric body is converted into rotational motion, and the rotational force is transmitted to the outside of the motor via the rotational output shaft connected to the driven plate.

[Effects of the Invention] According to the above configuration, since the piezoelectric body is provided on the circumferential surface of the drive plate excluding the contact surface with the driven plate, the piezoelectric body whose vibration source is the force that presses the driven plate against the drive plate. Since the piezoelectric body is not directly applied to vibration, the vibration of the piezoelectric body is not restricted, and therefore the driving efficiency of the motor can be improved. Further, the above structure allows easy lamination, and a large driving torque can be obtained by lamination.

[Example] The present invention will be explained below with reference to illustrated embodiments.

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 the upper and lower housing walls, and one end thereof projects outside the housing and is connected to a driven body (not shown).

An annular drive plate 1 is disposed in the housing 5 around the rotary output shaft 7, and the drive plate 1 has a thick inner peripheral end and projects upward and downward, and each projecting end surface serves as a contact surface 11. be. And, on these contact surfaces 11, driven plates 3a,
3b is the contact point.

Details of the drive plate 1 and driven plates 3a, 3b are shown in FIG. In the figure, the drive plate 1 has cuts made at equal intervals on its inner periphery, and a plurality of vibrating pieces 12 are formed by these cuts. Therefore, these vibrating pieces 12 have 'MA's whose tips protrude in the radial direction.
Upper and lower end surfaces of each leg portion 13 (FIG. 3) constitute the contact surface 11.

Annular piezoelectric plates 2a and 2b are bonded to the upper and lower surfaces of the outer peripheral portion of the drive plate 1 along the base ends of the vibrating pieces 12, and these piezoelectric plates 2a and 2b are arranged alternately at equal intervals in the circumferential direction. The reason is that their polarization directions are different.

At this time, the polarization position of each of the upper and lower piezoelectric plates 2a and 2b is 90°.
(Fig. 4). Each of the piezoelectric plates 2a and 2b has a ring-shaped electrode 21.
a, 21b are joined, and these annular electrodes are connected via lead wires to alternating current power supplies 10a, 10b which respectively emit outputs with a phase shift of 90°. The drive plate 1 is grounded as a common electrode.

Each of the driven plates 3a and 3b that contacts the drive plate 1 has an annular shape, and is fixed at a plurality of locations on its circumferential surface to the leg tips of leaf springs 6a and 6b whose support legs extend radially. The above plate spring 6
Oval attachment holes 61a and 61b are provided at the centers of a and 6b, respectively.

Then, the mounting holes 61a and 61b are fitted into the oblong mounting portion of the rotary output shaft 7 while the drive plate 1 is sandwiched between the driven plates 3a and 3b from above and below.

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

The outer circumferential end of the drive plate 1 is brought into contact with a cushion material 51 provided on the inner circumferential wall of the housing 5 for positioning and prevention of rotation.

When sinusoidal voltages having a phase shift of 90° are applied to the piezoelectric bodies 2a and 2b, traveling wave vibrations are generated on the circumferential surface of the drive plate 1 as shown by the broken lines in FIG. Figures (1) and (2) show the time course of traveling wave vibration.

Along with this, a vibrating piece 12 formed on the inner peripheral part of the drive plate 1
performs torsional vibration with a phase shift of 180° from the traveling wave (
Figure 5 arrow). The resonant frequency of this torsional vibration is vibrating piece 1
2, the cross-sectional shape, and the moment of inertia of the mass portion 13, and by appropriately setting these, the vibrating element 12 causes a large resonance vibration in response to the traveling wave vibration of the drive plate 1. The vibrational displacement of the mass part 13 is shown by the vertical line along the wavy line in FIG.

Thus, the upper and lower ends of the mass portion 13 periodically contact the upper and lower driven plates 3a, 3b, and are suppressed to rotate in the direction of the arrow in the figure by the circumferential component of torsional vibration.

According to the above structure, since the pressing force for bringing the drive plate 1 and the driven plates 3a, 3b into close contact is not directly applied to the piezoelectric bodies 2a, 2b, which are the drive sources, the vibration of the piezoelectric bodies is not restricted, and the drive efficiency is improved. I can figure it out. Also, the vibrating piece 1 provided with the mass part 13
2 constitutes the contact surface 11, and the vibrating pieces 12 are made torsionally resonate, so that a larger rotational force can be obtained.

Other embodiments of the present invention are shown in FIGS. 6 and 7. In FIG. 6, a plurality of drive plates 1a, 1b are arranged around the rotation output shaft 7.
are arranged, and driven plates 3a, 3b, 3C are arranged alternately on the inner periphery of the drive plates 1a, 1b, sandwiching them therebetween. The driven plates 3a and 3C are held between leaf springs 6a and 6b, and by adjusting the adjusting nut 9 provided on the outer periphery of the rotary output shaft 7, the driving plates 1a and 1b and the driven plates 3a, 3b and 3c can be pressed. Pressure can be adjusted. FIG. 7 shows a partially exploded perspective view of this embodiment. By forming the driving plate and the driven plate in a multi-plate configuration in this way, even greater rotational output can be obtained.

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

As shown in FIG. 8, it may be configured 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 rotation output shaft 7
The drive plate 1 disposed around the drive plate 1 has an inner circumferential edge within its thickness and projects upward, and this protruding end surface serves as a contact surface 11 with the driven plate 3, and the contact surface 11 is formed at equal intervals in the circumferential direction. The vibrating piece 12 with a mass part 13 at its tip is cut into a piece (Fig. 9).

The drive plate 1 has an outer peripheral portion supported by a cushion material 51 provided on the bottom and inner peripheral surfaces of the housing 5.

This structure allows the motor to have a flat shape, which is advantageous when the installation space for the motor is limited.

The vibrating piece 12 may have the shape shown in FIGS. 10 and 11. That is, in the former case, the mass portion 13 is hollowed out at the center to adjust its mass. With this shape, the amount of vertical protrusion of the mass portion 13 is maintained constant and the mass can be changed and adjusted. Further, the latter has a semi-circular shape formed on both sides of the vibrating element 12, and such a shape allows torsional vibration to be easily generated.

The contact surface 11 may be provided on the outer periphery of the drive plate 1. In FIG. 12, annular drive plates 1a, 1b are arranged around the rotational output shaft 7, and the drive plates 1a, 1b are made to protrude vertically with their outer circumferential ends within the thickness, and the driven plates 3a, 3b, 3
The contact surface 11 is cut at equal intervals in the circumferential direction to form a large number of vibrators. The above drive plate 1
Annular piezoelectric plates 2a and 2b are joined to the upper and lower surfaces of the inner peripheral parts of the drive plates 1a and 1b, and the inner peripheral ends of the drive plates 1a and 1b are connected to the rotation output shaft 7.
It is brought into contact with a cushion material 51 provided between.

The drive plates 1a, 1b have rod-shaped stoppers 14 erected at a plurality of locations on the outer peripheral surface, and the tips of each stopper are inserted into locking holes 52 provided in the opposing side walls of the housing 5. The locking hole 52 is in the shape of an elongated hole extending in the vertical direction, so that the drive plate 1 can vibrate vertically and is prevented from rotating.

According to this configuration, processing of the contact surface 11 is easy;
Since the relatively expensive piezoelectric body can be made smaller, costs can be reduced.

[Brief explanation of the drawing]

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 the main parts, FIG. 4 is a perspective view of the drive plate, FIG. 5 is an explanatory diagram of the operation, 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,
Figure 8 is an overall sectional view, Figure 9 is an enlarged view of the main parts, and
0 and 11 are enlarged views of main parts showing the fourth and fifth embodiments of the present invention, respectively, FIG. 12 is an overall sectional view showing the sixth embodiment of the present invention, and FIG. 13 is a conventional example. FIG. 1.1a, 1b... Drive plate 11... Contact surface 2.2a, 2b... Piezoelectric plate (piezoelectric body) 3.3a
, 3b, 3c -----・Following plate 6.6a, 6b
・・・・・・Plate spring 7・・・・・・Rotation output shaft 10a, 10b・・・・・・AC power source 1 Figure v, 2 Figure 3 Figure 4 Figure 10a 10b Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13

Claims (3)

[Claims] (1) The drive plate is annular and its inner or outer circumferential surface is used as a contact surface with the driven plate, and piezoelectric materials with different polarities are arranged alternately in the circumferential direction on the circumferential surface of the drive plate other than the contact surface. The piezoelectric body is arranged so that an alternating voltage is applied to the piezoelectric bodies to generate traveling wave vibration that moves in the circumferential direction on the contact surface, and the driven plate provided on the rotational output shaft is elastically applied to the contact surface. A piezoelectric vibration motor characterized by being brought into contact with the (2) The contact surface is cut at equal intervals in the circumferential direction and divided into a plurality of vibrating pieces by these cuts, and each vibrating piece has its tip as a mass part that projects in the radial direction to generate torsional vibration, and each of the above The piezoelectric vibration motor according to claim 1, wherein the driven plate is brought into elastic contact with the protruding end surface of the mass part. (3) The piezoelectric vibration motor according to claim 1 or 2, characterized in that the piezoelectric vibration motor has a laminated structure in which the driving plate and the driven plate are laminated in multiple stages.