CN1360394A - Standing-wave ultrasonic motor rotating bidirectionally - Google Patents

Abstract

The bidirectionally rotatable standing wave ultrasonic motor belongs to the technical field of piezoelectric actuators, and is characterized in that it contains: a piezoelectric motor with the same polarization direction and equal spacing in each area on the lower end surface, the number of divisions is 4 times the number of wavelengths, and the upper end surface is a unified electrode. The electric ceramic ring piece and the stator composed of a metal ring connected with it and having driving teeth arranged at equal intervals in the circumferential direction, the center of which is located in the center of the polarization zone, and the number of teeth is twice the number of wavelengths, consists of a friction ring piece in close contact with the driving teeth and The rotor composed of the metal ring connected to it, the central shaft, the preload adjustment mechanism composed of the central shaft adjustment screw and the elastic adjustment piece, the inner wall has the ring bushing for the positioning of the central shaft, the base of the ball bearing and the housing, wherein, The stator is fixed to the base at the center, the piezoelectric ceramic ring slices are energized as a whole, and in the two adjacent partition segments, every two pairs of partitions are externally connected with power supplies of different polarities. It has the advantages of simple ceramic polarization process, simple driving method, convenient installation and adjustment, stable rotation, and large output torque.

Description

Standing wave ultrasonic motor with bidirectional rotation

technical field

A standing wave ultrasonic motor capable of bidirectional rotation belongs to the field of piezoelectric drivers.

Background technique

Piezoelectric ultrasonic motors have a wide range of applications as driving components of precision instruments due to their fast response speed, self-locking when power is off, no electromagnetic disturbance, and low-speed operation, especially bidirectional standing wave piezoelectric ultrasonic motors. Competitiveness. In 1998, Japan's "Applied Physics" magazine (Jpn.J.Appl.Phys) No. 37 p2966-2969 pages, the name is "Effect of Pressing Force Applied to a Rotor on Disk-Type Ultrasonic Motor" (disc-shaped ultrasonic motor rotor) A standing wave piezoelectric ultrasonic motor is proposed in the paper, the structure of which is shown in Fig. 1-Fig. 2. It includes preload adjustment mechanism 11, rotor 12 and stator 13 three parts. Among them, the preload adjustment mechanism includes a nut 110, a spring 111, a bearing 112 and a positioning screw 113 in the middle; the rotor 12 is composed of a slotted metal disc 120 and a circular friction plate 121; 131. Composed of sensing ceramics 132 and driving piezoelectric ceramics 133, the driving piezoelectric ceramics 133 adopts alternate forward and reverse polarizations of different division intervals, and the teeth are located on the boundary line between two adjacent polarized areas of the same polarity . Applying alternating current to lead wires 1 and 2 respectively can excite the same vibration mode at different positions of the stator to realize bidirectional rotation. But it has the following disadvantages: 1. Due to the inconsistent polarization directions of the different divisions of the driving piezoelectric ceramic sheet 133, it brings difficulties to the ceramic polarization process, and it is difficult to ensure the consistency of the electrical parameters in the forward and reverse directions after polarization. Moreover, there is internal stress formed by polarization at the dividing line between the positive and negative polarization of ceramics, which will affect the pure vibration mode excited by the motor stator, and generally there will be some clutter interference; 2. The motor stator adopts a plate structure, which excites The mode of is (1,3) mode, that is, there is a pitch circle around the circumference of the stator. Generally, the stator of this mode is fixed at the pitch circle, but the motor is fixed at the central positioning screw, which will suppress the vibration of the motor stator and affect the output of the rotor torque; 3. The number of driving teeth of the motor stator is small, increasing The friction loss between the stator and the rotor is increased, which affects the service life of the motor.

Contents of the invention

The object of the present invention is to provide a standing wave ultrasonic motor capable of bidirectional rotation with simple ceramic polarization process, simple driving mode, convenient adjustment, stable rotor rotation, large output torque and long service life.

The present invention is characterized in that it contains: the polarization direction of each division area on the lower end surface is consistent, the spacing is equal and the number of divisions is four times the number of wavelengths, and the upper end surface is a piezoelectric ceramic ring piece with a unified electrode and connected to it. And the driving teeth are arranged at equal intervals in the circumferential direction and the center of the teeth is located in the center of the polarized area. The stator is composed of a metal ring whose number of teeth is twice the number of wavelengths. The rotor, the central shaft, the preload adjustment mechanism composed of the central shaft adjusting screw and the elastic adjustment piece, the inner wall has an annular bushing for positioning the central shaft and a standard ball bearing, and the base fixed to the stator at the center and the base connected to it The casing; wherein, while each partition is in an energized working state, in the two partition segments which are sequentially composed of two adjacent pairs of partitions and are adjacent to each other, the two pairs of partitions are respectively connected to control the positive and negative directions of the motor. Single-channel high-frequency AC signals of different polarities. Every two adjacent polarized areas on the piezoelectric ceramic ring piece are externally connected with a single-channel high-frequency AC signal for controlling forward and reverse rotation of the motor. The number of divisions in the division area is four times the number of wavelengths.

Proof of Use: It performs its intended purpose.

Description of drawings

Figure 1: A three-dimensional assembly diagram of an existing standing wave ultrasonic motor that can rotate in both directions.

Figure 2: Top view of the electrode division area driving the piezoelectric ceramic sheet in Figure 1.

Fig. 3: A cross-sectional view of the bidirectionally rotatable standing wave ultrasonic motor proposed by the present invention.

Fig. 4: Schematic diagram of the principle of the bidirectionally rotating standing wave ultrasonic motor proposed by the present invention.

Fig. 5: Schematic diagram of the distribution of the partitions a, b, c, and d on the lower end surface of the piezoelectric ceramic ring in the bidirectionally rotatable standing wave ultrasonic motor proposed by the present invention and its connection with a single high-frequency AC signal.

Fig. 6: A schematic diagram of the upper end face of the piezoelectric ceramic ring piece in Fig. 5 .

Detailed ways

In Fig. 2, "+" and "-" represent electric domains, that is, polarization directions, 1 and 2 respectively represent lead wires connected to a single high-frequency AC signal during forward and reverse rotation, and 1310 is a driving tooth.

In Fig. 3-Fig. 4, the upper end surface of the stator 21 is a unified electrode, and the electric domains in the polarized regions at the lower end have the same direction and the same spacing, and are separated by electrodes, and the piezoelectric ceramic ring piece 212 with the number of divisions four times the number of wavelengths and its Metal rings 211 bonded together. The consistent electric domain direction simplifies the ceramic polarization process and no internal stress will be generated in the polarization region. There are 8 driving teeth 2110 on the metal ring 211, and the spacing between each tooth differs by half a wavelength. The outer tooth side and the inner tooth side of each tooth 2110 adopt oblique angle design, and the tooth groove of the inner tooth side is deeper than the tooth groove of the outer tooth side. It is relatively close to ideal elastic deformation, which is also conducive to the high torque output of the motor. The rotor 20 is composed of a friction ring piece 202 in close contact with the driving teeth 2110 and a metal ring piece 201 bonded thereto. See Figure 4 for its driving principle. The symbols  and  in the figure represent the polarity of the applied voltage. When all the divisions are in the energized working state as shown in Figure 5, and under the condition that the standing waves A and B differ by 1/4 wavelength, the As shown in 5, partition a, i.e. a ₁ ~ a ₄ and partition b, i.e. b ₁ ~ b ₄ are in positive polarity, while partition c, i.e. c ₁ ~ c ₄ and d, i.e. d ₁ ~ d ₄ are in negative polarity, namely The vibration mode shown in Figure 4(b) can be obtained. If the divisions b and c are in the negative polarity a, and d is in the positive polarity, as shown in Figure 4(a), the motor rotation direction is opposite. As shown in Figure 4(b), the stator 21 always reciprocates within the range of the solid line and the dotted line, the P point is the antinode point of the ultrasonic vibration, and the N point is the node where the amplitude is always zero. The teeth 2110 are within the range of the left 1/4 wavelength of point P, causing the curve of the swing of the teeth 2110 to be oblique to the left, and then the moving direction of the rotor 20 is left. The arrows in the figure indicate the moving direction and distance of the tops of the driving teeth 2110 schematic diagram. The pre-tightening or pre-stress adjustment mechanism 23 is composed of a screw 230, a washer 231, a disc spring 232, a rubber ring 233 near the end of the central shaft 22 near the rotor 20, and a pre-stress adjustment washer 234 for positioning near the other side of the central shaft 22. , The standard shaft is made up of snap ring 235. The function of the screw 230 is to adjust the position of the central shaft 22 through the screw 230 when the motor is in use, so as to facilitate the alignment of the central shaft 22 and the external parts during the use of the motor. The inner wall of the base 24 has an annular shaft sleeve 241 and a standard ball bearing 242 for the positioning of the central shaft 22, and the stator 21 is fixed with the base 24 of the motor at the center, because the present invention adopts a ring structure, and the vibration is concentrated on the outer edge of the stator 21 , so it will not affect the vibration of the stator 21; moreover, there is no pitch circle on the stator, and the vibration is basically concentrated at the driving teeth 2110, which is also conducive to the high torque output of the motor.

In addition, the materials used for the metal ring piece 202 of the rotor 20 and the metal ring 211 of the stator 21 are aluminum and bronze, respectively.

It can be seen that the present invention has a series of advantages such as simple ceramic polarization process, simple driving method, stable rotor rotation, large output torque, and convenient adjustment and installation.

Claims (4)

1. A standing wave ultrasonic motor capable of bidirectional rotation, comprising a stator, a rotor and a preload adjustment mechanism, characterized in that it contains: the polarization direction of each division on the lower end surface is consistent, the spacing is equal and the division number is the wavelength The stator is composed of a piezoelectric ceramic ring sheet with four times the number, and the upper end surface is a unified electrode, and a metal ring connected to it and the driving teeth are arranged at equal intervals in the circumferential direction, and the center of the teeth is located in the center of the polarization zone. The number of teeth is twice the number of wavelengths , a rotor composed of a friction ring in close contact with the above-mentioned driving teeth and a metal ring connected to it, a central shaft, a preload adjustment mechanism composed of a central shaft adjusting screw and an elastic adjustment member, and the inner wall has a ring for positioning the central shaft A shaft sleeve and a standard ball bearing and a base fixed to the stator at the center and a casing connected to it; wherein, while each partition is in an energized working state, it is composed of two adjacent pairs of partitions in sequence and next to each other In the two partition sections, the two pairs of partitions are respectively connected to single-channel high-frequency AC signals of different polarities used to control the forward and reverse rotation of the motor. Every two adjacent polarized areas on the piezoelectric ceramic ring piece are externally connected with a single-channel high-frequency AC signal for controlling forward and reverse rotation of the motor. 2. The bidirectionally rotatable standing wave ultrasonic motor according to claim 1, characterized in that the spatial distances of the drive teeth differ by half a wavelength. 3. The bidirectionally rotatable standing wave ultrasonic motor according to claim 1, characterized in that the number of divisions in said division area is four times the number of wavelengths. 4. The standing wave ultrasonic motor capable of bidirectional rotation according to claim 1, characterized in that: one side of the piezoelectric ceramic ring adopts uniform electrodes, while the other side is divided by electrodes at equal intervals. The chemicalization direction is along the thickness direction of the ceramic.

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