CN1142624C - Piezoelectric film micromotor with single-diameter non-axisymmetric vibration mode - Google Patents

Abstract

The present invention relates to a piezoelectric membrane micromotor of a single-pitch diameter non-axial-symmetrical vibration mold, which belongs to the technical field of a piezoelectric micromotor. The present invention is characterized in that the piezoelectric micromotor comprises a stator, a hollow tube, rotors, a central shaft, a pretightening force adjusting mechanism and a stator support, wherein a thin metal wafer and a piezoelectric ceramic membrane form the stator together; the piezoelectric ceramic membrane symmetrically adheres to the thin metal wafer and can be continuously clockwise or anticlockwise energized on electrode partition areas of the thin metal wafer along a circumferential direction; the hollow tube is symmetrically fixed to the central part of the stator; the rotors are distributed on both ends of the hollow tube; the central shaft penetrates through the hollow tube and forms a clearance fit with the upper rotor; the pretightening force adjusting mechanism acts on the upper rotor and is composed of a screw nut and a spring; the stator support is supported on the periphery of the thin metal wafer. When the lower rotor and the central shaft are connected, a shaft output type motor is formed. The lower rotor is used as the support of the central shaft to form a rotor output type. The rotors and the hollow tube form inclination angle contact. The smoothness of the operation of the rotors is increased along with the increase of the quantity of the electrode partition areas. The present invention has the advantages of a rod-shaped micromotor and a piezoelectric membrane micromotor, and has the advantages of simple polarization processes, universality, easy microminiaturization and no influence on output torque.

Description

Piezoelectric film micromotor with single-diameter non-axisymmetric vibration mode

technical field

The invention relates to a piezoelectric film micromotor with a non-axisymmetric vibration mode of a single diameter, belonging to the technical field of piezoelectric micromotors.

Background technique

Piezoelectric ultrasonic motors are widely used as driving components of precision instruments due to their fast response speed, self-locking when power off, no electromagnetic disturbance, low-speed operation, easy miniaturization and flexible structural design. The existing rod-shaped piezoelectric micromotors and thin-film piezoelectric micromotors are the main types in the miniaturization of piezoelectric micromotors, and their disadvantages are: 1. The external dimensions of rod-shaped ceramic micromotors are restricted by technological conditions, and it is difficult to make more Small, this is because the piezoelectric ceramic rod or tube must be divided into at least 4 polarization areas on the outside or inside. If the size is too small, it will bring great difficulties to polarization, partition, electrical connection and testing. 2. The thin-film piezoelectric micro-motor mainly achieves the purpose of miniaturization from the thickness direction, and the force output is generally at the peak of the stator vibration, so the size difference between the stator and the rotor is not too much, and the radial size is difficult to reduce, otherwise , will reduce the output torque.

Contents of the invention

The object of the present invention is to provide a single-diameter non-axisymmetric vibration mode piezoelectric film micromotor which has both the advantages of mature technology of thin-film piezoelectric micromotors and the advantages of easy miniaturization and large output torque of rod-shaped piezoelectric micromotors. In the 2001 International Symposium on Micromechatronics and Human Science (International Conference on Micromechanical Electronics and Human Science), a paper entitled "PZT based Manipulators for Cell Biolog" (piezoelectric manipulators for cell biology) was published. The structure of the manipulator is shown in Figure 1. It mainly includes a manipulation probe 10 , a piezoelectric ceramic thin disc 11 and a thin metal disc 12 . The piezoelectric ceramic thin disc 11 is polarized along the thickness direction, and four 90-degree fan-shaped electrodes are evenly laid on the surface. Under the action of the thin piezoelectric ceramic disc 11, the manipulation probe 10 will produce a three-dimensional movement around the X axis, or around the Y axis, or along the Z axis as shown in the figure. When applying alternating current to sector electrodes 1 and 3, the probe 10 will swing relative to the Y axis; when applying alternating current to sector electrodes 2 and 4, the probe 10 will swing relative to the X axis; When the same polarity alternating current is applied, the probe 10 will reciprocate up and down along the Z axis. The surface of this piezoelectric ceramic thin disc 11 has a pitch diameter but no pitch circle when the vibration frequency is low, which we call the (1,0) vibration mode of the piezoelectric ceramic diaphragm; when the vibration frequency is high, there is One pitch diameter, one pitch circle, we call it (1,1) vibration mode. Its characteristic is that the piezoelectric ceramic diaphragm as the driving part is separated from the probe as the driven part, which provides an idea for the miniaturization of the driven part, as long as the driven part can be wound around the fixed part driven by the piezoelectric ceramic diaphragm Axis Z turns, and a brand new drive system is formed.

The present invention is characterized in that it contains: a stator composed of a thin metal disc and piezoelectric ceramic diaphragms symmetrically bonded to the upper and lower sides of the thin metal disc, and symmetrically fixed in the hollow space at the center of the above-mentioned stator. The tube, the rotor distributed at both ends of the hollow tube, passes through the central axis of the hollow tube and the upper rotor clearance fit, and acts on the pre-tightening force adjustment mechanism composed of nuts and springs on the upper rotor and supported on the outer periphery of the thin metal disc. The stator support; the hollow tube and the rotor rotate clockwise or counterclockwise by applying power to the electrode division area on one side of the piezoelectric film. The micro-motor is a shaft output type in which the lower rotor and the central shaft are joined together, the upper rotor and the central shaft are in clearance fit, and the upper and lower rotors are in contact with the hollow tube at an inner oblique angle. The micro-motor is a rotor output type in which the lower rotor is supported integrally with the central shaft, and the upper rotor is in clearance fit with the central shaft and in contact with the hollow tube at an inner oblique angle.

One side of the above-mentioned thin metal disc of the piezoelectric ceramic diaphragm bonded is a unified electrode, and the electrode on the other side is equally divided into 2N regions, N is at least equal to or greater than 2, and the polarization direction is along the thickness direction, and each electrode The polarization directions of the polarized regions are the same. Said split fraction 2N=4. The unified electrode is opposite in polarization direction to any pair of electrodes symmetrical to the central tube on the other side and is connected in series with the external power supply.

Proof of Use: It performs its intended purpose.

Description of drawings

Figure 1: Schematic diagram of the structure of an existing piezoelectric manipulator.

Figure 2: Schematic diagram of the operating principle of a piezoelectric film micromotor in a single-diameter non-axisymmetric vibration mode.

Figure 3: Embodiment 1: Schematic diagram of the structure of a piezoelectric film micromotor with a shaft output type single-diameter non-axisymmetric vibration mode.

Figure 4: A perspective view of the micromotor shown in Figure 3.

Figure 5: Embodiment 2: Schematic diagram of the structure of a piezoelectric film micromotor with a rotor output type single-diameter non-axisymmetric vibration mode.

Figure 6a-1, 6a-2, 6a-3: Three vibration modes of piezoelectric ultrasonic micromotor stator based on bending vibration mode: no node, one node and two nodes;

Figure 6b: Oscillating mode of a piezo-film micromotor hollow tube with a single-diameter non-axisymmetric vibration mode.

Figure 7: Stator connection diagram for series energization.

Detailed ways

Embodiment 1: Please refer to Fig. 2 to Fig. 4 . The motor structure includes a rotor 31 , a stator 32 , a pretightening force adjustment mechanism 30 and a support 33 . The stator 32 is composed of a thin metal sheet 321 and a thin piezoelectric ceramic diaphragm 320 bonded on its front and back surfaces with epoxy resin glue. The polarization of the piezoelectric ceramic membrane 320 along the thickness direction is consistent. There are four fan-shaped electrodes 1-4 on the upper surface, and a unified electrode on the other side. A hollow tube 322 is symmetrically fixed in the central hole of the thin metal sheet 321 . The two rotors 312 and 313 are symmetrically distributed at both ends of the hollow tube 322 , the central shaft 314 passes through the inner hole of the hollow tube 322 , and the lower rotor 313 is connected to the central shaft 314 . The two rotors 312, 313 are tightly matched with the hollow tube 322 under the action of the preload adjustment mechanism 30. The preload adjustment mechanism 30 includes a nut 300 and a spring 301. The nut 300 is threaded with the upper end of the central shaft 314 Cooperate, the pre-tightening force between the hollow tube 322 and the rotor 31 can be adjusted. The upper rotor 312 is in clearance fit with the central shaft 314 . The contact surface between the rotor 31 and the hollow tube 322 adopts an inner inclined angle contact, which eliminates the positioning of the bearing to the central axis 314, and can also improve the contact state, increase the output torque, and the polarity of the voltage applied to the ceramic surface There is a difference: when the AC power applied to intervals 2 and 4 differs by 1/4 wavelength from the alternating current applied to intervals 1 and 3, the hollow tube 322 will produce continuous circular swing, and the forward and reverse swings of the hollow tube 322 can be controlled The direction of rotation of the rotor 31, wherein the swing mode of the hollow tube is shown in Figure 6b. It can be seen from the figure that the hollow tube 322 is only a rigid body displacement without bending deformation, and the hollow tube 322 always has a certain vibration regardless of the vibration amplitude of the piezoelectric diaphragm during the swing. A node, and the instantaneous driving points on both sides of the stator are on the opposite side of the stator. The patent number is ZL97111805.1, and the name is "Piezoelectric Ultrasonic Micromotor Based on Bending Vibration Mode". There are three cases of three nodes, and the instantaneous driving points on both sides of the stator are on the same side of the stator. The division number of the ceramic surface is 2N, N≥2, and 2N=4 in this embodiment. It can be seen that when the pair of electrodes symmetrical to the hollow tube 322 on the piezoelectric ceramic diaphragm 320 is energized clockwise, the hollow tube 322 will continue to swing clockwise, and the rotor will also swing under the friction of the hollow tube 322. It will rotate clockwise, otherwise, it will rotate counterclockwise. The stability of the rotor operation is related to the number N of sector electrodes on the surface of the piezoelectric ceramic diaphragm 320 , the larger N is, the better the stability is. In addition, when the vibration frequency is low, the vibration mode is (1, 0), that is, there is a pitch diameter and no pitch circle. When the piezoelectric ceramic diaphragm is energized clockwise, the pitch diameter will rotate clockwise and the hollow tube 322 will swing clockwise, and the rotor 31 will also rotate clockwise; when the vibration frequency is high, the vibration mode is (1,1), That is, there is a pitch diameter, a pitch circle somewhere on the surface of the stator, and the rest are the same as the vibration mode (1, 0). FIG. 7 is to make the unified electrode and any pair of electrodes symmetrical to the central tube 322 have the same polarization direction, and both are connected to an external power supply, that is, in series.

Embodiment 2: Please refer to FIG. 5 . It differs from Embodiment 1 in that: the lower rotor is removed so that the central shaft 514 and the support 53 are integrated, that is, the lower rotor is made into a support body and connected with the central shaft 514, and the upper rotor 512 and the central shaft 514 are clearance fit. The swing of the hollow tube 522 only drives the upper rotor 512 to rotate clockwise or counterclockwise. Among them, 500 is a nut, 50 is a preload adjustment mechanism, 501 is a spring, 520 is a piezoelectric ceramic diaphragm, 521 is a thin metal disc, 52 is a stator, and 51 is a rotor.

It can be seen that the present invention has the advantages of both rod-shaped and thin-film piezoelectric micromotors, and its characteristics are as follows: 1. The polarization process is simple. When the motor is miniaturized, the planar structure of ceramic sheets and electrodes can be compared with many existing advanced manufacturing The means are compatible, easy to miniaturize and the consistency of electrical parameters after treatment is very good. 2. Appropriately increasing the division number N of the electrode area can improve the stability of the rotor operation. 3. The piezoelectric ceramic diaphragm 320 is separated from the driving part of the stator and the rotor, which is beneficial to the miniaturization of the diameter of the driving part itself. 4. Subsequently, the output torque will not be affected when the motor is miniaturized.

Claims (6)

1. A piezoelectric film micromotor with a single-section diameter non-axisymmetric vibration mode, which contains a stator, a rotor and a preload adjustment mechanism, is characterized in that it contains: a thin metal disc and a symmetrically bonded thin metal disc The stator composed of piezoelectric ceramic diaphragms on the upper and lower sides of the disc is symmetrically fixed on the hollow tube at the center of the stator, and the rotors distributed at both ends of the hollow tube pass through the hollow tube and fit the upper rotor gap. The central shaft acts on the upper rotor, the pre-tightening force adjustment mechanism composed of nuts and springs, and the stator support on the outer circumference of the thin metal disc; the hollow tube is activated by applying power to the electrode division area on one side of the piezoelectric film. , The rotor rotates clockwise or counterclockwise. 2. The piezoelectric film micro-motor with non-axisymmetric vibration mode of single-segment diameter according to claim 1, characterized in that: the micro-motor is that the lower rotor and the central shaft are conjoined and the upper rotor and the central shaft are in clearance fit, and the upper , Shaft output type in which the lower rotor contacts the hollow tube at an inner oblique angle. 3. The piezoelectric film micro-motor with non-axisymmetric vibration mode of single-segment diameter according to claim 1, characterized in that: in the micro-motor, the lower rotor is a support connected to the central shaft, and the gap between the upper rotor and the central shaft is Rotor output type that fits and contacts the hollow tube at an inward oblique angle. 4. According to claim 1, the piezoelectric film micro-motor with non-axisymmetric vibration mode of single-segment diameter is characterized in that: the side where the piezoelectric ceramic diaphragm is bonded to the above-mentioned thin metal disc is a unified electrode and the other The electrodes on one side are evenly divided into 2N regions, N is at least equal to or greater than 2, and the polarization direction is along the thickness direction, and the polarization directions of each polarization region are consistent. 5 . The single-segment diameter piezoelectric film micromotor with non-axisymmetric vibration mode according to claim 1 , characterized in that: the number of divisions 2N=4. 6 . 6. According to claim 4, the piezoelectric film micromotor of the non-axisymmetric vibration mode of single-section diameter is characterized in that: the polarization direction of the unified electrode and any pair of electrodes symmetrical to the central tube on the other side is The same and are commonly connected in series with the external power supply.

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