CN104362897A - Single-electric-signal-driven rotary ultrasonic motor - Google Patents

Abstract

The invention discloses a rotary ultrasonic motor driven by a single electric signal, which comprises a mandrel, a rear cover plate, a piezoelectric ceramic sheet, an electrode sheet, an elliptical vibration mode converter, a friction disc, Bearings, springs and nuts, the mandrel, rear cover plate, piezoelectric ceramic sheet, electrode sheet, and elliptical vibration mode converter constitute the stator part of the ultrasonic motor; the friction discs and bearings constitute the rotor part of the ultrasonic motor ; The spring and the nut constitute the positive pressure preload adjustment mechanism of the rotor part and the stator part of the ultrasonic motor. The present invention uses a specially designed elliptical vibration mode converter combined with straight beams and inclined beams, and utilizes a group of longitudinal vibration modes of piezoelectric ceramics to realize the elliptical track movement of the mass points on the end surfaces of the teeth driven by the stator to drive the rotor to rotate. The utility model has the advantages of simple structure, easy manufacture, easy miniaturization, integration, low cost, less difficult control, etc., and has broad application prospects.

Description

A Rotary Ultrasonic Motor Driven by Single Electric Signal

technical field

The invention relates to the field of ultrasonic motors utilizing the inverse piezoelectric effect of piezoelectric ceramics, in particular to a rotary ultrasonic motor driven by a single electric signal utilizing ultrasonic elliptical vibrations.

Background technique

The rotary ultrasonic motor is a new type of micro-motor developed and applied rapidly in the 1980s. It is an electromechanical coupling device that uses the inverse piezoelectric effect of piezoelectric materials to convert electrical energy to mechanical energy. Through the friction between the stator and the rotor, the The micro-vibration of the elastomer is converted into the macro-rotational motion of the rotor, which directly pushes the load. In the existing rotary ultrasonic motors, there are generally problems such as small driving torque, large axial volume, large wear difference between the inner and outer diameter contact areas of the stator and rotor, and low working reliability.

The mode conversion ultrasonic motor driven by a single electric signal is also a kind of ultrasonic motor. It is driven by a group of piezoelectric ceramic elements, and the stator generates complex vibration with two vibration modal components through a mode converter with a special structure. . If there is a certain phase difference between the two vibration modes and the frequency is similar, the end surface particle of the stator on the contact interface between the stator and the rotor will generate an elliptical trajectory vibration, thereby obtaining the motion and torque of the rotor through the friction between the stator and the rotor .

In the patent document with the publication number CN101860259A and the invention name "Single Electric Signal Excited Rotary Ultrasonic Motor", a method is disclosed that uses a window-shaped dislocation mode converter to convert the longitudinal vibration generated by the sandwich vibrator into the elliptical vibration of the driving tooth point. , and then drive the ultrasonic motor to rotate the rotor. The control and drive system of the invention is simple and easy to assemble, but the manufacturing of the window-shaped dislocation mode converter is difficult and the production cost is high, which restricts its promotion and application in industrial production.

In the patent document with the publication number CN101030740A and the invention name "Single-phase Driven Bending Rotary Ultrasonic Motor", a single-phase drive standing wave rotating ultrasonic motor with a tapered body structure is disclosed. The axially stacked piezoelectric ceramic sheets excite the vibration of the stator, and the six piezoelectric ceramic sheets are fixed on the central shaft by means of compression nuts and pressure shaft sleeves. Although the motor has the advantages of large output torque, etc., its structure is complicated, and the screw movement (rotation force) of the compression nut during the compression process of the piezoelectric ceramic sheets is very easy to cause misalignment between the piezoelectric ceramic sheets, which is difficult to achieve. The technical requirement to ensure a 60-degree misalignment between adjacent piezoelectric ceramic sheets; in addition, there is no positioning device between the stator and the rotor of the motor, which affects the accuracy of the contact position between the stator and the rotor, thereby affecting the motor. Stability of torque and speed; This type of rotating ultrasonic motor has problems such as complex structure, difficult manufacturing and installation, high cost, and poor stability of motor torque and speed.

Contents of the invention

The present invention provides a new type of rotary ultrasonic motor driven by a single electric signal. A rotary ultrasonic motor driven by a large single electrical signal.

A rotary ultrasonic motor driven by a single electric signal, characterized in that it includes a mandrel and a rear cover plate, a piezoelectric ceramic sheet, an electrode sheet, an elliptical vibration mode converter, a friction disc, a bearing, and a spring that are sequentially sleeved on the mandrel and nuts; the mandrel, rear cover plate, piezoelectric ceramic sheet, electrode sheet, and elliptical vibration mode converter constitute the stator part of the ultrasonic motor, and the mandrel and elliptical vibration mode converter are connected by threads The cover plate, piezoelectric ceramic sheet, electrode sheet and elliptical vibration mode converter are compressed and fixed to form the energy conversion part of the ultrasonic motor, which converts the ultrasonic electric energy output by the ultrasonic power supply into the ultrasonic vibration energy of the stator part.

The elliptical vibration mode converter is an integrated structure, including a lower cylindrical part and an upper driving tooth part, and the driving tooth part is uniformly arranged on the upper end of the cylindrical part in the circumferential direction, and the number of driving teeth is 3-12 pieces, the projection of each drive tooth along the radial direction is a composite structure of straight beams and inclined beams, the geometric central axis of the straight beam is parallel to the axis of the cylindrical part, and one end of the straight beam is connected to the front end of the cylindrical part , the other end is overhanging; one end of the inclined beam is connected to the side where the front end of the cylindrical part deviates from the axis of the straight beam, and the other end is connected to the middle part of the straight beam. The geometric central axis of the inclined beam and the geometric central axis of the straight beam are 0 The included angle is -90 degrees, and the connection between the straight beam and inclined beam and the cylindrical part is a circular arc transition connection.

The purpose of making the driving tooth form a straight beam and inclined beam composite structure is to change the vibration mode of the elliptical vibration mode converter, so that the longitudinal vibration mode frequency and the bending vibration mode frequency of the driving tooth are close to or equal. With the existence of the inclined beam composite structure, the longitudinal ultrasonic vibration generated by the energy conversion part of the ultrasonic motor is decomposed into a part of the longitudinal vibration component and a part of the bending vibration component at the root of the inclined beam after being transmitted to the inclined beam. When the longitudinal vibration component decomposed by the inclined beam and After the bending vibration component is transmitted to the straight beam, it is combined with the longitudinal vibration propagating on the straight beam, and finally forms an ultrasonic elliptical vibration at the end of the straight beam with a certain phase difference between the longitudinal vibration component and the bending vibration component, which is converted into an elliptical vibration mode The state converter drives the longitudinal-bending composite ultrasonic elliptical vibration of the tooth end along the tangential direction of the ultrasonic motor circle.

The friction disc and the bearing constitute the rotor part of the ultrasonic motor; the spring and the nut constitute the positive pressure pretightening force adjustment mechanism of the rotor part and the stator part of the ultrasonic motor.

Furthermore, the end of the driving tooth of the elliptical vibration mode converter is bonded with A friction material.

Furthermore, the end surface of the friction disc that is in contact with the driving teeth is bonded with B friction material.

Furthermore, the rear cover plate and the mandrel can be made into a separate structure or an integrated structure.

The stator of the present invention adopts a sandwich-type transducer structure, utilizes a specially designed elliptical vibration mode converter, and utilizes a group of longitudinal vibration modes of piezoelectric ceramics to realize the elliptical trajectory motion of the particle end face of the stator driving the tooth, and drive the rotor to rotate, with a structure Simple, large power capacity, easy manufacture, low assembly difficulty and other advantages; in addition, the present invention only needs a set of control circuit and its drive power supply, the control drive system is simple, easy to manufacture, less difficult to control, and high in reliability; at the same time, the present invention has volume Small size, light weight, easy miniaturization, integration, low cost, high torque at low speed, low noise, fast response, high positioning accuracy, no electromagnetic interference and strong environmental adaptability, etc., have broad application prospects.

Description of drawings

Fig. 1 is a schematic structural view of the present invention.

Fig. 2 is a three-dimensional exploded schematic view of parts of the present invention.

Fig. 3 is a schematic diagram of the three-dimensional structure of the elliptical vibration mode converter of the present invention.

Fig. 4 is a schematic diagram of an application example of the present invention.

Explanation of symbols in the figure: 1. Mandrel, 2. Back cover, 3. Piezoelectric ceramic sheet, 4. Electrode sheet, 5. Elliptical vibration mode converter, 6. A friction material, 7. B friction material, 8 .Friction disc, 9. Bearing, 10. Spring, 11. Nut, 12. Ultrasonic power supply.

Detailed ways

As shown in Figures 1, 2, 3, and 4, the single electric signal-driven rotary ultrasonic motor of the present invention includes a mandrel 1 and a back cover 2, a piezoelectric ceramic sheet 3, and an electrode sheet 4 that are sequentially sleeved on the mandrel 1 , elliptical vibration mode converter 5, friction disc 8, bearing 9, spring 10 and nut 11; The stator part that constitutes the ultrasonic motor is connected through the external thread on the mandrel 1 and the internal thread of the elliptical vibration mode converter 5, and the back cover 2, the piezoelectric ceramic sheet 3, the electrode sheet 4 and the elliptical vibration mode The state converter 5 is compressed and fixed, which constitutes the energy conversion part of the ultrasonic motor, which can convert the ultrasonic electric energy output by the ultrasonic power supply 12 into the ultrasonic vibration energy of the ultrasonic motor. The rear cover 2 and the mandrel 1 are manufactured in a split structure.

The elliptical vibration mode converter 5 is an integrated structure, including a cylindrical part at the lower end and a driving tooth part at the upper end. The driving tooth part is evenly arranged on the upper end of the cylindrical part in the circumferential direction, and the number of driving teeth is 6. Each The projection of each driving tooth along the radial direction is a composite structure of straight beams and inclined beams, and the projection of each driving tooth along the radial direction is a composite structure of straight beams and inclined beams. The geometric central axis of the straight beam and the cylindrical part The axes are parallel, one end of the straight beam is connected to the front end of the cylindrical part, and the other end is overhanging; one end of the inclined beam is connected to the side where the front end of the cylindrical part deviates from the axis of the straight beam, and the other end is connected to the middle part of the straight beam. The geometric central axis of the beam and the geometric central axis of the straight beam form an included angle of 30 degrees, and the joints between the straight beam and the inclined beam and the cylindrical part are arc transition joints, and the radius of the arc is 1mm.

The width of the straight beam projected by the drive tooth along the radial direction is 2 mm, and the height is 7 mm. The width of the inclined beam projected by the drive tooth along the radial direction is 1.5 mm. A friction material 6 is bonded to the end of the drive tooth.

The friction disc 8 and the bearing 9 constitute the rotor part of the ultrasonic motor. The friction disc 8 and the bearing 9 are connected together by a transition fit and then sleeved on the mandrel 1. The end surface of the friction disc 8 in contact with the driving teeth is bonded with B friction material 7 The spring 10 and the nut 11 constitute the positive pressure preload adjustment mechanism of the ultrasonic motor rotor part and the stator part, and the compression amount of the spring 10 can be changed by adjusting the position of the nut 11 on the mandrel 1, thereby adjusting the motor rotor to the motor stator The pre-pressure is set to 6N.

The external diameter of the rotary ultrasonic motor driven by a single electric signal is 10mm, the length is 53mm, the piezoelectric ceramic used is PZT-8, the size is Ф10×Ф5×2mm , the natural frequency is 101.5KHz, the impedance is 56 ohms, the dynamic resistance is 17 ohms, the ultrasonic power supply 12 The output voltage range is 0-400V, the current range is 0-4A, the output frequency is 101.5±0.01KHz, and the ultrasonic power supply 12 has an automatic frequency tracking function within the specified frequency range.

As shown in FIG. 4 , during operation, after the electrode sheet 4 of the rotating ultrasonic motor driven by a single electric signal is connected to the electrical signal output by the ultrasonic power supply 12, due to the inverse piezoelectric effect of the piezoelectric ceramic sheet 3, the piezoelectric ceramic sheet 3 will Generate longitudinal ultrasonic vibration, that is, convert the electric energy output by the ultrasonic power supply 12 into ultrasonic vibration energy, and drive the entire stator to perform longitudinal ultrasonic vibration. When the ultrasonic vibration energy is transmitted from the stator to the end of the elliptical vibration mode converter 5, it is converted into a Longitudinal vibration with a certain phase difference and bending vibration compound longitudinal-bending composite ultrasonic elliptical vibration, which is converted into elliptical vibration mode converter 5 drives the longitudinal-bending composite ultrasonic elliptical vibration of the end of the drive tooth along the tangential direction of the ultrasonic motor circumference, drives the end of the tooth and friction The discs 8 are in contact with each other, and then drive the rotor to rotate. After the ultrasonic motor runs continuously for 30 minutes, the output voltage of the ultrasonic power supply 12 is 100V, the current is 0.24A, and the rotation speed of the rotor is 536r/min. The operation is in good condition.

Claims (4)

1. A single electric signal drives a rotary ultrasonic motor, characterized in that: it comprises a mandrel and a rear cover plate, a piezoelectric ceramic sheet, an electrode sheet, an elliptical vibration mode converter, a friction disc, and a bearing that are sequentially sleeved on the mandrel , springs and nuts; the mandrel, rear cover plate, piezoelectric ceramic sheet, electrode sheet, and elliptical vibration mode converter constitute the stator part of the ultrasonic motor, and the mandrel and the elliptical vibration mode converter are connected by threads Press and fix the rear cover plate, piezoelectric ceramic sheet, electrode sheet and elliptical vibration mode converter; the friction disc and the bearing constitute the rotor part of the ultrasonic motor; the spring and the nut constitute the rotor part and the stator part of the ultrasonic motor Positive pressure preload adjustment mechanism; the elliptical vibration mode converter is an integrated structure, including a cylindrical part at the lower end and a driving tooth part at the upper end, and the driving tooth part is evenly arranged on the cylindrical body in the circumferential direction At the upper end of the part, the number of driving teeth is 3-12, and the projection of each driving tooth along the radial direction is a composite structure of straight beams and inclined beams. The geometric central axis of the straight beam is parallel to the axis of the cylindrical part, and the straight beam One end of the slanted beam is connected to the front end of the cylindrical part, and the other end is overhanging; one end of the slanted beam is connected to the side where the front end of the cylindrical part deviates from the axis of the straight beam, and the other end is connected to the middle part of the straight beam. The geometric central axis of the slanted beam It forms an angle of 0-90 degrees with the geometric central axis of the straight beam, and the joints between the straight beam and the inclined beam and the cylindrical part are all arc transition joints. 2. The rotary ultrasonic motor driven by a single electric signal according to claim 1, characterized in that: the rear cover plate and the mandrel are made into a separate structure or an integrated structure. 3. The rotary ultrasonic motor driven by a single electric signal according to claim 1 or 2, characterized in that: A friction material is bonded to the end of the driving tooth of the elliptical vibration mode converter. 4. The rotary ultrasonic motor driven by a single electric signal according to claim 1 or 2, characterized in that: B friction material is bonded to the end surface of the friction disc that is in contact with the drive teeth.