JPH0327781A - Linear type ultrasonic motor - Google Patents

Abstract

PURPOSE:To obtain a linear type ultrasonic motor with a large thrust and a wide speed control range by generating the elliptic motion of a standing wave through a longitudinal vibration piezoelectric element and a slip vibration piezoelectric element to take out a linear output. CONSTITUTION:If a high frequency voltage B is applied between electrode 6A, 6B of a transverse vibration unit 4, a reverse piezoelectric action is generated in slip vibration piezoelectric elements 5A, 5B so that a vibrator 9 is displaced to the right. Then, the reverse piezoelectric action is also generated in longitudinal vibration piezoelectric elements 2A, 2B and the vibrator 9 is displaced upward while decreasing in the displacement to the right-hand direction so as to be pressure-welded to an output member 12. After that, the vibrator 9 reaches the lower longitudinal limit position transversely in the center. Thereafter, when a series of similar displacements of the vibrator 9, i.e., an elliptic motion is repeated, the output member 12 moves linearly and continuously.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a linear type ultrasonic motor (prior art) Conventionally, rotary type ultrasonic motors using traveling waves have been known. In the linear ultrasonic mode,
Due to the influence of reflected waves, etc., it is difficult to adopt a traveling wave drive system as is, and various attempts have been made to absorb the reflected waves and effectively extract the traveling waves. For example, in a linear surface wave motor, a piezoelectric element fixed to a predetermined location on an elastic body generates a surface wave that circulates around the elastic body through the inverse piezoelectric action, and the surface wave in a predetermined direction applies a linear thrust to the moving body. I try to give. (Problem to be solved by the invention) However, in such a conventional linear ultrasonic motor, since the elastic body is vibrated by a piezoelectric element fixed to the elastic body, it is difficult to change the drive voltage. If you do so, both the traveling wave and the longitudinal vibration wave will change.For this reason, the range in which speed can be controlled is narrow relative to the rated speed, making it impossible to use it for servo motors, etc., and making it difficult to obtain large thrust. (Objective of the Invention) Therefore, the present invention generates an elliptical motion of a standing wave using a longitudinal vibration piezoelectric element and a sliding vibration piezoelectric element to extract a linear output. (Means for Solving the Problem) In order to achieve the above object, the present invention provides a linear type ultrasonic motor with a wide range of a sliding vibration piezoelectric element which is laminated in the same direction as the longitudinal vibration piezoelectric element and has an electrostrictive direction of slip perpendicular to the lamination direction, and is excited by the longitudinal vibration piezoelectric element and the sliding vibration piezoelectric element, A vibrator that amplifies vibrations from a vibrating piezoelectric element, and a moving body that is biased onto the vibrator and moves linearly in the electrostrictive direction of the sliding vibrating piezoelectric element as the vibrator moves. (Function) In the present invention, a longitudinal oscillating piezoelectric element is stacked in the electrostrictive direction and a sliding oscillating piezoelectric element is stacked in the same direction, and vibration is caused by the reverse piezoelectric action of both piezoelectric elements. The vibrator moves approximately elliptically while at least amplifying the shear vibration, and the movable body urged on the vibrator moves linearly in the direction of the shear vibration.Therefore, the longitudinal vibrating piezoelectric element and the shear vibrating piezoelectric Since no flexural vibration occurs in the element other than in the electrostrictive direction, it is possible to increase the amount of vibration by making both piezoelectric elements into an optimal laminated structure, and it is possible to obtain a large thrust that is further amplified by the vibrator. By driving the alternating current applied voltages of both piezoelectric elements with separate drive circuits, the longitudinal vibration piezoelectric element can be
A linear ultrasonic motor with a wide speed control range is provided, in which the alternating current voltage applied to the shear vibrating piezoelectric element can be varied while the oscillating piezoelectric element is fixed. (Example) Hereinafter, the present invention will be explained based on the drawings.

1 to 6 are diagrams showing one embodiment of the present invention.

In FIGS. 1 to 4, 1 is a longitudinal vibration unit, and the longitudinal vibration unit 1 includes a plurality of longitudinal vibration piezoelectric elements 2A and 2B stacked in the electrostrictive direction, and each longitudinal vibration piezoelectric element 2A.
, 2B, which are arranged to sandwich the electrodes 3A and 3B. The longitudinally vibrating piezoelectric elements 2A and 2B are arranged alternately and have different polarization directions as shown schematically in FIGS. 2(a) and 2(b). ) is applied, the longitudinal vibration piezoelectric element 2A
, 2B expand and contract in the vertical direction (vertical direction) in FIG. 4 is a transverse vibration unit, and the transverse vibration unit 4 further includes a plurality of sliding vibration piezoelectric elements 5A and 5B stacked on the vertical vibration unit 1 in the same direction as the vertical vibration piezoelectric elements 2A and 2B, respectively;
It consists of a plurality of electrodes 6A and 6B arranged to sandwich each sliding vibrating piezoelectric element 5A and 5B. The sliding vibration piezoelectric elements 5A and 5B are arranged alternately so that the polarization direction is as shown in FIG. 3(a).
As shown in (b), when a voltage (described later) is applied between the electrodes 6A and 6B, the transverse vibration unit 4 is moved in the electrostrictive direction (inverse piezoelectricity) by the reverse piezoelectric action of the sliding vibration piezoelectric elements 5A and 5B. It is designed to expand and contract in the horizontal direction in Figure 1, which is the direction of strain caused by the action. Further, the vertical vibration unit 1 and the horizontal vibration unit 4 have coaxial through holes 1a and 4a passing through the center thereof, and a support bolt 7 has its head 7h vertically in the through holes 1a and 4a. It is inserted into vibration unit 1 so as to collide with it. and,
A cylindrical vibrator 9 disposed on the horizontal vibration unit 4, the vertical vibration unit 1, and the horizontal vibration unit 4 are fastened together with a predetermined preload by a nut 8 screwed onto the support bolt 7. The vibrator 9 has an inner diameter that is approximately the same as the through hole 4a of the transverse vibration unit 4, and is movable in the radial direction with respect to the support bolt 7 and the nant 8. It is vibrated in the lateral direction due to the piezoelectric effect, and the vibration is amplified. Specifically, the vibrator 9 has a resonant frequency that matches the frequency of the AC applied voltage between the electrodes 6A and 6B, which is a high-frequency voltage with a constant amplitude as shown in FIG. When receiving ultrasonic vibration from the unit 4, it moves horizontally in an ellipse while amplifying the sliding vibration from the lateral vibration unit 4. On the other hand, an output member 12 (moving body) is provided on the vibrator 9, sandwiching the lining material 11, and the output member l2 is connected to a valve spool or the like at an end (not shown) and is A coil spring 14 biases the transverse vibration unit 4. The coil spring 14 has its end face polished, etc., and has a nasoto 15 and a spring receiver 1 screwed to the support bolt 7.
6, it is compressed to a predetermined length and generates a predetermined spring pressure. Further, the press plate 13 has a lining material 17 that comes into contact with the output member l2, and the coefficient of friction between the lining material 17 and the output member 12 is the same as that between the lining material 11 and the output member l2.
It is smaller than the friction coefficient of 2. When the vibrator 9 moves in an elliptical manner as described above, the output member 12 rubs against the lining material l1, which moves in an elliptical manner together with the vibrator 9, due to the biasing force from the coil spring l4, as indicated by the arrow X in FIG. Move linearly in the direction. Note that l8 is a guide sleeve fixed to the nasoto 8 or the support port 7, and the guide sleeve l8 is slidably engaged with the elongated hole 12a formed in the output member 12 (see FIG. 5) and the press plate 13. At the same time, the output member 12 and the pressing member 13 are guided. In addition, in FIG. 4, the applied voltage B or C between the electrodes 6A and 6B is +90° or -90° with respect to the applied voltage A between the electrodes 3A and 3B.
By switching the applied voltage BSC from one side to the other side, the moving direction of the output member 12 can be reversed. Next, the effect will be explained.

A high frequency voltage A of a predetermined voltage is applied to the longitudinal vibration unit 1, and a high frequency voltage B of a predetermined voltage is applied to the transverse vibration unit 4.
Or when C is applied, the vibrator 9 is ultrasonically vibrated by the electrostrictive action of the longitudinal vibration piezoelectric elements 2A, 2B and the sliding vibration piezoelectric elements 5A, 5B, and the sliding vibration piezoelectric elements 5A, 5B
The vibration from the coil spring 1 is amplified, and then the coil spring
The output member 12 biased by the vibrator 9 by the output member 4 rubs against the lining material 1l and moves linearly, thereby driving a valve stub, etc. not shown.

Now, if a high frequency voltage B is applied between the electrodes 6A and 6B of the transverse vibration unit 4, first, as shown in FIG. 9 is displaced to the right in the figure, and then in Figure 6 (
As shown in b), a reverse piezoelectric effect also occurs in the longitudinally vibrating piezoelectric elements 2A and 2B, causing the vibrator 9 to displace upward and reduce the displacement in the right direction, thereby coming into pressure contact with the output member 12. Next, as shown in FIG. 6(c), the vibrator 9 is further displaced to the left while the upward displacement is decreased, and the output member 12 is moved to the left by the frictional force. Next, as shown in FIG. 6(d),
The vibrator 9 reaches the lower limit position in the vertical direction at the center in the horizontal direction, and thereafter, a series of similar displacements of the vibrator 9, that is, elliptical movements are repeated, so that the output member 12 continuously moves linearly. On the other hand, if the applied voltage C is applied between the electrodes 6A and 6B of the transverse vibration unit 4, then the vertical vibration piezoelectric element 2A
, 2B, the electrostrictive action of the sliding vibrating piezoelectric elements 5A, 5B occurs, and the output member l2 moves backward.

In such a state, the longitudinal vibration piezoelectric elements 2A, 2B and the sliding vibration piezoelectric elements 5A, 5B vibrate only in their respective electrostrictive directions, and do not produce deflection vibrations in directions other than the electrostrictive directions, so that the longitudinal vibration unit 1 And, by making the transverse vibration unit 4 have a multilayer structure, a sufficient vibration amplitude can be obtained, and the amplification effect of the vibrator 9 is also added, so that the thrust can be efficiently increased without increasing the voltage values of the applied voltages A and B. Can be done. Further, by fixing the applied voltage A and varying the voltage value of the applied voltage B, the moving speed of the output member 12 can be controlled over a wide range, and in particular, speed control in the ultra-low speed region becomes easy. Therefore, a linear ultrasonic motor with a large thrust and a wide speed control range is provided. In this embodiment, the vertical movement of the vibrator 9 is limited to a predetermined amount by the nasoto 8 in order to effectively extract only the linear output of the output member 12, but the nut 8 is omitted. to increase the longitudinal amplitude of the vibrator 9,
For example, the vibrator 9 can also amplify the longitudinal vibration from the longitudinal vibration unit l.

(Effects) According to the present invention, longitudinally vibrating piezoelectric elements are stacked in the electrostrictive direction and slidingly vibrating piezoelectric elements are stacked in the same direction, and the vibrator excited by the reverse piezoelectric action of both piezoelectric elements is at least slidably vibrated. Since the movable body is moved in a straight line by amplifying the motion, the vertical vibration piezoelectric element and the shear vibration piezoelectric element can be made into a multilayer structure that does not cause flexural vibrations in directions other than the electrostrictive direction. , it is possible to provide a linear ultrasonic motor with a large thrust by increasing the amount of vibration of the vibrator. Further, it is possible to vary the amount of excitation of the sliding vibrating piezoelectric element while fixing the amount of excitation of the longitudinally vibrating piezoelectric element, and it is possible to provide a linear ultrasonic motor with a wide speed control range.

[Brief explanation of drawings]

1 to 6 are diagrams showing one embodiment of the linear type ultrasonic motor according to the present invention, in which FIG. 1 is a front sectional view thereof, FIG. 2(a) is a plan view of its longitudinally vibrating piezoelectric element, FIG. 2(b) shows the Bt −B of FIG. 2(a)! 3(a) is a plan view of the sliding vibration piezoelectric element, FIG. 3(b) is a cross-sectional view of B and B3 in FIG. 3(a), and FIG. 4 is a high-frequency wave applied to the piezoelectric element. A voltage waveform diagram, FIG. 5 is a partial plan view of the moving body, and FIG. 6 is an explanatory diagram of its operation. 2A, 2B...
...Longitudinal vibration piezoelectric element, 5A, 5B ... Sliding vibration piezoelectric element, 9 ... Vibrator, 12 ... Output member (moving body).

Claims (1)

[Claims] A longitudinally vibrating piezoelectric element laminated in the electrostrictive direction, a shear vibrating piezoelectric element laminated in the same direction as the longitudinal vibrating piezoelectric element and having an electrostrictive direction perpendicular to the lamination direction, a longitudinal vibrating piezoelectric element, and a shear vibrating element. a vibrator that is excited by the piezoelectric element and amplifies at least the vibration from the sliding vibration piezoelectric element;
A linear ultrasonic motor comprising: a moving body that is biased onto a vibrator and moves linearly in the electrostrictive direction of a sliding vibrating piezoelectric element as the vibrator moves.