JPH0226282A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To make the speed and starting torque of an apparatus higher by fixedly arranging a non-resonating, expansible and contractible laminated ceramic actuator on the central principal plane of a vibrator functioning in a longitudinal vibration secondary mode. CONSTITUTION:An ultrasonic motor is composed of a stainless steel rectangular flat plate 31, a piezoelectric actuator 32, a copper roller 33, a spring 34, and piezoelectric ceramic plates 35, 37-39. The polarized arrangement of said piezoelectric ceramic plates is such that ceramic plates 38-39 contract when ceramic plates 35, 37 extend, and the resonance frequency of a longer direction longitudinal vibration secondary mode and the tension of said spring 34 in said vibrator are adjusted to 25kHz and 10kgf, respectively. Thus, when the AC electric field of 25kHz is applied to ceramic plates 35, 37-39 and that with the same frequency and a phase advancing by 20 deg.-30 deg., to said actuator 32, said roller 33 rotates in the direction of the arrow 301.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a motor that utilizes ultrasonic vibration energy.

(Prior technology) Conventionally, as an ultrasonic motor, a piezoelectric ceramic plate is bonded to one side of an elastic plate, and the two resonance frequencies of longitudinal vibration in the longitudinal direction and bending vibration in the width direction are made to match or approach each other, and an electric field of a frequency near the two resonance frequencies is generated. A standing wave type ultrasonic motor has been proposed that uses a vibrator (hereinafter referred to as a bending multimode vibrator) that excites the two vibrations in a degenerate state by applying the above-mentioned vibrations to a piezoelectric body. This will be explained below with reference to the drawings.

First, an example of a longitudinal-bending multi-mode oscillator is shown in Fig. 4(a)~
Shown in (d). This is a vibrator that excites first-order longitudinal vibration in the length direction and first-order bending vibration in the width direction in a degenerate state.

FIG. 4(a) is a front view, and FIG. 4(C) is a side view.

Metal electrode films 43 are provided on both upper and lower surfaces of a piezoelectric ceramic plate 42 that is uniformly polarized in the thickness direction, and are bonded to the bottom surface of an elastic plate 41. At this time, the elastic plate 41 and the piezoelectric ceramic plate 42 are dimensioned so that the resonant frequencies of the first-order longitudinal vibration mode in the length direction and the first-order bending vibration mode in the width direction match. 2 between the metal electrodes of such a vibrator
By applying an AC voltage equal to the resonance frequency of the two vibration modes, a standing wave having an amplitude displacement distribution shown in FIGS. 4(b) and 4(d) is excited. Here, 44 in Fig. 4(b) is the displacement distribution of the first-order longitudinal vibration in the length direction, and the fourth
45 in the figure (d) indicates the displacement distribution of the first-order bending vibration in the width direction. In this way, the longitudinal-flexural multimode oscillator has two
Different types of vibration modes were degenerated and used.

Further, as shown in FIG. 5, the roller had a structure in which it was fixed to the national body 54 by a spring 52 via an elastic plate 41 and silicone rubber 53.

(Problems to be Solved by the Invention) The standing wave type ultrasonic motor using the above-mentioned vibrator has higher speed and driving force than the conventional ultrasonic motor using traveling waves, and the driving method By devising the shape of the elastic plate, even higher speeds and higher driving forces are possible.

In addition, because it is necessary to match the resonant frequencies of multiple modes: longitudinal vibration in the longitudinal direction and bending vibration in the width direction, there is a small degree of freedom when designing the vibrator. Spurious vibrations caused by multiple higher-order longitudinal bending vibrations occur near the longitudinal vibration mode, and it is extremely difficult to suppress these spurious vibrations.Therefore, the drawback is that it is difficult to drive with self-excitation. was there.

In addition, in order to increase the torque of the roller, it is necessary to press the roller against the vibrator, but conventionally the roller 51 is pressed against the vibrator by inserting a spring 52 between it and the national body 54, as shown in FIG. was.

With this method, ■force is applied to the national polity, making the national polity thinner and
It is not possible to reduce the weight. ■ When pressure welded with strong force, the silicone rubber 53 deforms and the vibrator tilts. ■ Bending vibration is weak against pressure welding (There were problems such as the vibration amplitude becoming smaller when the pressure welding was increased.) .

(Means for Solving the Problems) The present invention provides a non-resonant and expandable multilayer ceramic actuator that is bonded and fixed on the central main surface of a rectangular flat plate vibrator that operates in a secondary mode of longitudinal vibration in the longitudinal direction. The ultrasonic motor is characterized in that it rotates a roller that is pressed against the actuator by a spring using the longitudinal vibration secondary mode of the rectangular vibrator and the non-resonant vibration of the laminated actuator.

(Function) FIGS. 1(a) and 1(b) are a side view and a displacement distribution diagram of the basic configuration of the ultrasonic motor according to the present invention, respectively. FIG. 2 is an enlarged view of the main parts of FIG. 1. This will be explained below with reference to the drawings.

In the rectangular flat plate vibrator 11, the longitudinal vibration secondary mode in the longitudinal direction is in a resonant state at a certain frequency. The displacement distribution at that time is shown in FIG. 1(b) 15. As can be seen from the displacement distribution 15, the maximum displacement is obtained at the center of the vibrator 11. The state of vibration at the center is shown in FIG. 2 C1d. Since the actuator can be displaced in the direction C1d in FIG. Rotate.

Conversely, if a and d, b and C occur simultaneously, the roller 13 will rotate in the direction f.

Since a spring is inserted between the rotation axis of the roller 13 and the rectangular flat plate vibrator 11, the roller 13 is statically pressed against the actuator.

Here, the tension of the spring is perpendicular to the longitudinal direction, and the equivalent stiffness of the spring in the a1b direction is small, so the vibrations a and b do not become small due to the influence of the spring. Further, since the tension of the spring acts only between the rectangular flat plate vibrator 11 and the roller 13, the characteristics of the motor do not depend on the external national body.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 3 is a diagram showing one embodiment of the ultrasonic motor of the present invention. In Figure 3, 31 is a stainless steel rectangular flat plate;
2 is a piezoelectric actuator, 33 is a steel roller, 34 is a stainless steel spring, 35, 37, 38, 39 is a piezoelectric ceramic plate, and 36 is a silver baked electrode. The dimensions of the vibrator are that the rectangular flat plate 31 has a length of 160mm, a width of 18mm, and a thickness of 3mm! I11. The piezoelectric actuator 32 is 10 cm cubic, and the piezoelectric ceramics 35, 37, 38, and 39 are all 50 cm long, 18 mm wide, 0.5 mm thick, and 35.3 mm thick.
The polarization arrangement is such that when the ceramic plate 7 expands, the ceramic plate 38.39 contracts. In this vibrator, the resonance frequency of the second mode of longitudinal vibration is 25kHz.
It becomes z. Further, the spring 13 was adjusted to have a static tension of 10 kgf.

Baking is from electrode 36 to ceramic plate 35.37.38.3
A 25kHz AC electric field is applied to actuator 3.
When an alternating current electric field having the same frequency and a phase lead of 20 to 30 degrees was applied to the roller 2, the roller rotated in the direction of the arrow 301. Compared to an ultrasonic motor using a longitudinal-flexural multimode vibrator, when the volume of the ceramic was the same, a maximum speed of about 1.5 times and a starting torque of about 3 times were obtained.

(Effects of the Invention) As described above, according to the present invention, it is possible to realize a thin, high-driving-power motor that utilizes ultrasonic energy.
It has the advantage of making equipment ultra-thin and lightweight, and has great industrial value.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are basic configuration diagrams of the vibrator of the present invention,
Figure 2 is an enlarged view of the main parts, Figure 3 is a configuration diagram of an embodiment, Figures 4(a) and (C) are basic configuration diagrams of a conventional vibrator, and Figure 4 (
b) and (d) are displacement distribution diagrams, and FIG. 5 is a basic configuration diagram of a conventional ultrasonic motor. In the figure, 11.41 is a rectangular flat plate, 31 is a stainless steel rectangular flat plate, 12 is a piezoelectric actuator, 32 is a piezoelectric actuator, 13.51 is a roller, 33 is a copper roller, 14
．． 52 is a spring, 34 is a stainless steel spring, 15.44
．． 45 is a displacement distribution, 35, 37, 38, 39, 42 is a piezoelectric ceramic plate, 3B, 43 is a silver baking electrode, 53 is a silicone rubber, 54 is a national body, and 301 is a rotation direction of a roller.

Claims (1)

[Claims] A non-resonant and expandable multilayer ceramic actuator is bonded and fixed on the central main surface of a rectangular flat plate vibrator that operates in a secondary mode of longitudinal vibration in the longitudinal direction.A roller is attached to the multilayer ceramic actuator with a spring. 1. An ultrasonic motor characterized by having a configuration in which the ultrasonic motor is pressure-welded.