JPS63262068A - Vibration wave motor - Google Patents

Abstract

PURPOSE:To reduce the size and the weight of a vibration wave motor by exciting a plurality of standing vibrating waves displaced perpendicularly to a rodlike vibrators, and rotatably moving the mass point of the vibrator by the composite vibration to frictionally driving a rotor. CONSTITUTION:A vibration wave motor is composed of a disclike rotor 1, a rodlike vibrator 2, and electromechanical energy converter PZTs 3-4', and AC voltages 6-7' of predetermined phase relation are appled to the PZTs 3-4' to rotatably drive the rotor 1. In this motor, the vibrator 2 is supported at its center by a support 5, and low-order mode vibration of bending standing wave is excited at the vibrator 2 by applying the AC voltage. Thus, the rotor 2 pressed on the vibrator 2 can be efficiently rotated.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention is directed to a rod-shaped vibrating body that is pierced in a cross section perpendicular to the longitudinal direction by standing wave vibrations with different vibration displacement directions generated in the rod-shaped vibrating body. The present invention relates to a vibration wave motor that drives a rotating body that is in pressurized contact with the vibrating body by causing rotational movement.

[Background of the Invention] Conventionally, an ultrasonic vibrator generates a traveling wave, which is a combination of a transverse wave and a longitudinal wave, on the surface of an elastic body, and the rotation of an 8'#J body is brought into pressure contact with the elastic body. It has been proposed to construct a motor by converting motion into motion or unidirectional motion (Japanese Patent Application Laid-open No. 148682/1982).

Since such a soter has a relatively small number of parts, it can be made smaller and lighter. However, since this motor uses traveling waves, it is essential to have a structure that circulates vibration waves, so it is still not possible to achieve sufficient size and weight reduction. In addition, since transverse waves and longitudinal waves are not independent, increasing the amplitude of longitudinal waves to increase the driving speed also increases the amplitude of transverse waves, which has the disadvantage of producing noise, and reducing the longitudinal waves also reduces the transverse waves, causing movement. There were drawbacks such as the inability to move the body sufficiently.

[Object of the Invention] In view of the above-mentioned prior art, the present invention has been made to provide a compact, lightweight and
The purpose is to provide a vibration wave motor with excellent motor controllability.

[Summary of the Invention] The vibration wave generator of the present invention generates two standing vibration waves that are displaced in two directions orthogonal to a rod-shaped vibrating body to which an AC-energized electro-mechanical energy conversion element is bonded. excite,
Therefore, as a synthesis of the standing vibration waves, there is mutually opposite rotation in the cross section perpendicular to the longitudinal direction of the rod-shaped vibrating body, and also in both left and right portions bordering on the longitudinal center of the rod-shaped vibrating body. a rod-shaped vibrating body configured to generate rotational motion of a mass point of the rod-shaped vibrating body in a direction, and a disk having a diameter parallel to the rod-shaped vibrating body and pressed into contact with the rod-shaped vibrating body. It is characterized by comprising a shaped rotating body.

[Embodiment of the Invention] FIG. 1 is a schematic partial perspective view of an embodiment of a vibration wave motor according to the present invention, and FIG. 2 is a schematic side view of a rectangular bar-shaped vibrating body 2 thereof. In the figure, 1 is a disc-shaped rotating body, made of resin.
Made of metal etc. However, the part in contact with the vibrating body 2 is
Made of wear-resistant material such as alumite. Reference numeral 2 denotes a rectangular bar-shaped vibrating body, which is made of a material with low vibration damping such as metal, such as aluminum alloy, copper alloy, iron alloy, etc. However, the contact portion with the rotating body 1 is made of a material such as cemented carbide that has better wear resistance than the rotating body 1, and has a high hardness imparted to the surface. In addition, in the combination of both the rotating body 1 and the vibrating body 2, it is desirable that the mutual coefficient of friction is large and its fluctuation is small with respect to temperature.

Therefore, brake materials and clutch materials such as asbestos rubber that satisfy the above conditions are preferably used.

3.3° and 4.4' are electrical-mechanical energy conversion elements, and PZT, which is a type of piezoelectric element, is preferably used. Therefore, the electrical-mechanical energy conversion element 3,3°
, 4,4° is hereinafter referred to as PZT. PZT 3 and 3
° is on the bottom surface of the vibrating body 2, PZT4 and 4° are on the bottom surface of the vibrating body 2
is joined to the side of the Hereinafter, the vibrating body 2 to which these PZTs are bonded will be referred to as a vibrator.

AC voltages 6.6°, 7, and 7° having appropriate phase relationships are applied to PZTs 3, 3°, and 4.4', respectively.

For example, if the polarization direction of each PZT is set in the direction of the adhesive surface with the vibrating body 2, the angular frequency of the AC voltage will be ω = 2π
f, the applied AC voltages 6 and 6° are VY=V,
5ina+t, AC voltage 7 is l/x=V2sin(
ωt+2/π), AC voltage 7゛ is vx' = V2sin
(ωt-2/π). If the central part of the rod-shaped vibrating body 2 is supported by the support 5 and the above-mentioned AC voltage is applied to excite the low-order mode vibration of the bending standing wave in the vibrating body 2, vibration as shown in FIG. 3 will occur.

In this case, the X, Y, and Z directions are taken as shown in FIG.

The frequency f is made to match the natural frequency of the vibrator in the thickness direction and width direction. In this case, the cross-sectional shape of the vibrator is designed so that the natural frequencies in the thickness direction and the width direction of the vibrator coincide.

As shown in FIGS. 3(a) and (b), at one end of the oscillator, x = a sin ωt, y = x b c
If the vibration os ωt is excited in the X and Y directions,
At one end, the vibrator is (x/a) in a plane perpendicular to the Z axis.
A rotational movement is performed along an ellipse of 2+(y/b)2=1. At the other end of the vibrator, the X-direction vibrations are temporally out of phase, so an elliptical motion of opposite rotation occurs. Therefore, the rotating body 1 in suppressing contact with the vibrator should ideally be a
It rotates at a circumferential speed of ω.

As shown in FIG. 4, if a protrusion 8 is provided on the part of the rotor 1 that contacts the vibration abdomen of the vibrating body 2, that is, the both ends of the vibrating body 2, the vibrator can move the rotor 1 at different feed speeds. It is more efficient because it does not come into contact with other parts of the body. For the same reason, a projection of 8° may be provided on the vibrator side as shown in FIG.

As can be seen from the above, the rotation speed of the rotor 1 depends on the vibration speed of the vibrating body 2 in the X direction when the amplitude of the vibrating body 2 in the Y direction reaches its maximum, that is, when it comes into contact with the rotor.
Adjusting the X-direction amplitude when the Y-direction amplitude is maximum, that is, PZT (in this example, 4 and 4
By adjusting the values of AC voltages 7 and 7゛ applied to ゛), or by adjusting the phase difference of the amplitudes in the By changing the phase difference, the rotation speed of the rotor 1 can be controlled.

Also, as an example of combining bending standing vibration waves, Figure 6 (a
), (b) may be excited, or a second-order mode, a third-order mode, etc. may be combined. In this case, if the design increases the number of contact points between the vibrating body 2 and the rotary body 1, it will be advantageous to improve the torque.

In the previous explanation, FX=FY was used as the X direction frequency FX and Y direction frequency FY, but F×=mFY (m is an integer)
The rotor can be rotated even if When m=2, the vibration motion locus in a cross section perpendicular to the length direction becomes a figure-eight shape.

In the examples shown in Figures 3 and 6, bending vibration waves are used for both the X-direction vibration and the Y-direction vibration, but depending on the cross-sectional shape and dimensions of the vibrator, the vibration in the rotor feeding direction, that is, the X-direction vibration in the previous example, may be In some cases, it may be more advantageous to utilize torsional vibration of the rod, and this case is also within the scope of the present invention because the cross section perpendicular to the longitudinal direction of the vibrating body performs rotational motion.

Furthermore, when considering the efficiency of a vibration wave motor, support of the vibrator is an important element.
In the type of motor described in Publication No. 2, the vibration wave is a traveling wave, and the position of the node changes over time, so it is difficult to support the motor at the node, and it is supported using absorbent material such as felt. There was a lot of energy loss. In the present invention, by aligning the nodal positions of each photographing standing wave and supporting the vibrating body 2 at this nodal position (in the examples of FIGS. 3 and 6, the central part of the vibrating body 2), it is possible to easily Joint support with less energy loss is possible.

Regarding the structure of the contact portion between the vibrator and the rotating body, since Y-direction vibration is also applied to the rotating body, when the amplitude becomes large, the rotating body vibrates, causing noise generation. Therefore, in order to prevent vibrations in this direction from being transmitted to the rotating body main body, an example in which the contact portion of the rotating body 1 with the vibrating body has spring properties in the Y direction is shown in FIGS. 7 and 8, which are cross-sectional views of the rotating body, respectively. It is. In the example of FIG. 7, the rotating body 1 is structurally given a spring property, and in the example of FIG. Rings made of metal etc. are joined together. However, in either case, high rigidity is provided in the circumferential direction. The reason for this is that since the circumferential direction is the direction in which the rotating body driving force acts, if appropriate rigidity is not provided, the stopping accuracy and starting accuracy of the motor will be significantly impaired.

The driving force of the rotating body is obtained from the frictional force caused by pressurizing the vibrator, but if this pressurization is done by magnetic force, such as by using a ferromagnetic material or a permanent magnet as the rotor or vibrating body, it is possible to use a pressure spring, etc. is no longer necessary, making it more compact.

In addition, an embodiment is also possible in which a plurality of rod-shaped vibrating bodies 2 are arranged in parallel or radially, and the disk-shaped rotating body 1 is pressed into contact with these.

[Effects of the Invention] In the vibration wave motor of the present invention, a plurality of standing vibration waves that are displaced in mutually orthogonal directions are excited in a rod-shaped vibrating body, and the combined vibration causes vibrations in the longitudinal direction of the vibrating body. Since the mass point of the vibrating body is rotated in a vertical cross section, and the rotating body pressed by the rod-shaped vibrating body is frictionally driven, the motor can be made smaller and lighter. Since the and lateral vibrations are applied independently, the motor has excellent controllability and generates less noise, and the vibrating body can be easily supported at the nodes, reducing energy loss. There is an advantage.

[Brief explanation of drawings]

Fig. 1 is a perspective view schematically showing an embodiment of the vibration wave motor of the present invention, Fig. 2 is a side view of its vibrator, Fig. 3(a),
(b) is a diagram showing the vibration state of the vibrator, FIG. 4 is a perspective view showing another embodiment of the rotating body in the present invention, and FIG. 5 is a side view showing another embodiment of the vibrator in the present invention. , FIGS. 6(a) and 6(b) are diagrams showing the vibration state of the vibrator in another embodiment of the present invention, and FIGS. 7 and 8 are diagrams showing other embodiments of the rotating body in the present invention, respectively. FIG. 1... Rotating body 2... Vibrating body 3.3°, 4
, 4°... Electric-mechanical energy conversion element (PZT) 5... Support rod 6.6°, 7,7°... AC voltage source 8.8°... Protrusion 9... Damper ( Rubber, felt, etc.) 10...Contact members Figure 1 Figure 6 Figure 7

Claims (10)

[Claims] (1) Excite two standing oscillating waves displaced in two directions orthogonal to the rod-shaped vibrating body to which an AC-energized electric-mechanical energy conversion element is connected, and thereby excite the standing oscillating waves. As a synthesis, the rod-shaped vibration is generated in a cross section perpendicular to the length direction of the rod-shaped vibrating body, and in which the directions of rotation are opposite to each other in both the left and right portions of the rod-shaped vibrating body with the center portion in the length direction as a border. A rod-shaped vibrating body configured to generate rotational motion of a mass point of the body, and a disc-shaped rotating body having a diameter parallel to the rod-shaped vibrating body and pressed into contact with the rod-shaped vibrating body. Features a vibration wave motor. (2) The vibration wave motor according to claim 1, wherein the two standing vibration waves to be excited are bending standing vibration waves. (3) The vibration wave motor according to claim 1, wherein the two standing vibration waves excited are a bending standing vibration wave and a torsional vibration. (4) The vibration wave motor according to claim 1, characterized in that one or more node positions of the standing vibration waves to be excited are made to coincide with each other, and a rod-shaped vibrating body is supported at the node positions. . (5) The vibration wave motor according to claim 1, characterized in that a plurality of rod-shaped vibrators are provided in parallel or radially. (6) The vibration wave motor according to claim 1, characterized in that a protrusion is provided near the vibrating abdomen of the rod-shaped vibrating body. (7) The vibration wave motor according to claim 1, characterized in that a protrusion is provided on the rotating body side near a position where the rod-shaped vibrating body contacts the vibrating abdomen position. (8) The protrusion of the rotating body has a spring property, and the spring property is hard in the circumferential direction of the rotating body and soft in the thickness direction (direction perpendicular to the circumferential and radial directions). A vibration wave motor according to claim 1. (9) The vibration wave motor according to claim 1, wherein the motor rotation speed is controlled by changing the alternating current voltage applied to the electro-mechanical energy conversion element or its phase. (10) The vibration wave motor according to claim 1, wherein the rod-shaped vibrating body and the rotating body are brought into pressure contact by magnetic force.