CN100530930C - Rotary sonic surface wave motor - Google Patents

Abstract

The rotary surface acoustic wave motor of the invention belongs to the field of surface acoustic wave motors. It consists of a stator assembly, an interdigital transducer, a rotor and a bracket assembly. The motor uses the characteristic that the surface acoustic wave can propagate on the curved surface, and designs a semi-annular stator, which excites the surface acoustic wave on its inner surface, sandwiches the rotor between the two stator half-rings, and through the action of friction to rotate The form of movement transmits power. This kind of motor has fast response, high output force, easy miniaturization, and can realize high-precision positioning control.

Description

Rotary surface acoustic wave motor

Technical field:

The rotary surface acoustic wave motor of the invention belongs to the field of surface acoustic wave motors.

Background technique:

The surface acoustic wave motor is a new type of motor naturally produced during the development of ultrasonic motors. It is the application of surface acoustic wave technology in ultrasonic motors. Surface waves are used to obtain the elliptical motion of the stator surface particles, and the motion is transmitted to a new type of actuator through the liquid coupling or direct friction coupling between the stator and the slider. At present, linear motors based on surface acoustic wave technology are developing very rapidly in Japan, and there are related reports in China. The article "Research and Development of Surface Acoustic Wave Linear Motor" in Volume 37, Issue 3 of "Micro-motor" magazine in 2004, has made a certain introduction to this linear motor of surface acoustic wave technology. However, there are no reports on the successful development of the rotary surface acoustic wave motor at home and abroad.

Invention content:

The purpose of the present invention is to develop a rotary surface acoustic wave motor with simple structure, high torque, high efficiency, fast response speed, small step distance and wider application range.

The present invention utilizes the characteristic that surface acoustic waves can propagate on curved surfaces, designs a semi-annular stator, excites surface acoustic waves on its inner surface, sandwiches the rotor between two half-rings of the stator, and through the action of friction, rotates The form of the movement conveys the movement.

The stator assembly includes an upper stator half-ring and a lower stator half-ring opposite to it, wherein the opposite end faces of the upper stator half-ring and the lower stator half-ring respectively form a slope shape indented from the outer ring to the inner ring; The above-mentioned rotor is clamped in the middle by the upper stator half-ring and the lower stator half-ring, and the surface of the rotor is covered with micron-scale bosses;

The bracket assembly includes an upper mounting seat and a lower mounting seat. The upper stator half-ring and the lower stator half-ring are glued to the inner ring surfaces of the upper mounting seat and the lower mounting seat respectively, and the upper mounting seat and the lower mounting seat are connected by spring gaskets. and the compression bolts provide the motor with the required pre-pressure during operation;

The interdigital transducers include upper and lower sets of interdigital transducer pairs, wherein the upper interdigital transducer pairs are processed on the left and right inclined surfaces of the upper stator half ring and the lower stator half ring, and the lower The interdigital transducer pairs are processed on the left and right inclined surfaces of the lower stator half-ring opposite to the upper stator half-ring;

The above-mentioned two sets of interdigital transducer pairs are all power combiner-type energy circulation structures, and the specific composition is as follows:

The lower interdigital transducer pair is composed of the left conversion electrode and the left reflection electrode installed on the left slope of the lower stator half ring, the right reflection electrode and the right conversion electrode installed on the right slope of the lower stator half ring, and a power combiner. The periodic node length and the acoustic aperture width of the above four electrodes are the same; wherein the left conversion electrode is connected to the port II of the power combiner, the right conversion electrode is connected to the port I of the power combiner, and the driving power is connected to the drive signal input end of the power combiner;

When the port I is used as the input terminal and the port II is used as the output terminal, that is, after the electrical signal of the acoustic synchronization frequency is added to the left conversion electrode, the surface acoustic wave excited on the surface of the lower stator half ring will be on the left and right sides of the left conversion electrode. propagating in two directions, the left reflecting electrode reflects all the surface acoustic waves propagating to the left to the right, and the distance between the left reflecting electrode and the left converting electrode satisfies the phase difference between the wave after reflection and the wave originally propagating to the right as 2nπ, n It is an integer, so that the intensity of the wave propagating to the right can be strengthened; when the wave propagates to the right conversion electrode, the piezoelectric effect, the right conversion electrode converts mechanical energy into electrical energy, and the electric signal of the acoustic synchronous frequency input by the drive power supply is input to the In the power combiner, it is applied to the left conversion electrode again, and through the inverse piezoelectric effect, the surface acoustic wave is excited on the inner ring surface of the lower stator half ring;

The composition form of the upper interdigital transducer pair is similar to that of the lower interdigital transducer pair, and the surface acoustic waves in the opposite direction of the lower stator half ring are excited on the upper stator half ring; Under the action of the elliptical motion of the surface particles of the stator, a friction force is generated, and the friction force pushes the rotor to rotate in the direction opposite to the wave propagation direction;

When the port II is used as the input end and the port I is used as the output end, the reverse rotation of the motor is realized.

In addition to the general characteristics of the ultrasonic motor, the rotary surface acoustic wave motor has the biggest characteristic because of its high driving frequency (MHz), while the driving frequency of the general ultrasonic motor is at the kHz level, so compared with the general ultrasonic motor Said that the wavelength of the surface acoustic wave used by the surface acoustic wave motor is very short, which is very conducive to miniaturization; the use of high-frequency sinusoidal signal excitation can realize forward and reverse motion, and the driving circuit is simple; the large-stroke stator structure design method is adopted. It overcomes the defect of the short stroke of the linear surface acoustic wave motor and realizes the continuous rotary motion; It is necessary to increase the output force of the rotor by increasing the contact area between the stator and the rotor, and to prevent the contradiction between the phase shift in the surface wave propagation process caused by the over-density of the bosses; the rotor structure clamped by the two annular stators effectively solves the problem of pre-pressure The potential for increasing the torque is great; the structure of the interdigital transducer is designed with the energy circulation method, so that the efficiency of the motor has been greatly improved.

Description of drawings:

Figure 1 is a schematic diagram of the structure of the stator and rotor of a rotary surface acoustic wave motor.

Fig. 2 is a structural schematic diagram of the stator, rotor and support mechanism of the rotary surface acoustic wave motor.

Fig. 3 is a schematic diagram of the stator substrate and the IDT processed on the inclined surface.

Fig. 4 is a schematic diagram of clockwise rotation of the rotor driven by surface acoustic waves.

Fig. 5 is a schematic diagram of counterclockwise rotation of the rotor driven by surface acoustic waves.

Designation of labels in Fig. 1: 1-rotor, 2-upper interdigital transducer pair, 3-upper stator half-ring, 4-lower stator half-ring, 5-lower interdigital transducer pair.

Designation of labels in Fig. 2: 6-upper mounting base, 7-lower mounting base, 8-pressing bolt, 9-elastic gasket.

Label name in Fig. 3: 10-left conversion electrode, 11-left reflection electrode, 12-right reflection electrode, 13-right conversion electrode, 14-drive power supply, 15-port I, 16-for drive signal input terminal, 17- Port II, 18 - Power combiner.

Labels and symbol names in Figure 4: 19-the direction of the elliptical movement of the surface particles of the stator half-ring, 20-the propagation direction of the surface acoustic wave, 21-the direction of the friction force on the rotor, 22-the rotation direction of the rotor, 23-the combination of the two stator half-rings The pre-pressure applied to the rotor; P, Q, R, S, T are the contact points between the stator half-ring and the rotor.

Detailed ways:

The working principle and specific implementation of the rotary surface acoustic wave motor will be described in detail below.

As shown in Figure 1 and Figure 2, it consists of a stator assembly, an interdigital transducer, a rotor and a bracket assembly, and is characterized in that: the stator assembly includes an upper stator half-ring 3 and a lower stator half-ring opposite to it 4, wherein the opposite end faces of the upper stator half ring 3 and the lower stator half ring 4 respectively form a slope shape indented from the outer ring face to the inner ring face; the rotor 1 is clamped by the upper stator half ring 3 and the lower stator half ring 4 The rotor 1 is held in the middle, and the surface of the rotor 1 is covered with micron-scale bosses; the interdigital transducer includes two sets of upper and lower interdigital transducer pairs, which are energy circulation method structures, wherein the upper interdigital transducer The pair 2 is processed on the two slopes opposite to the lower stator half ring 4 on the upper stator half ring 3, and the lower IDT pair 5 is processed on the two slopes opposite to the upper stator half ring 3 on the lower stator half ring 4. on the slope; the bracket assembly includes an upper mounting seat 6 and a lower mounting seat 7, and the upper stator half-ring 3 and the lower stator half-ring 4 are glued to the inner ring surfaces of the upper mounting seat 6 and the lower mounting seat 7 respectively. The seat 6 and the lower mounting seat 7 provide the required pre-pressure for the motor to work through the spring washer 9 and the compression bolt 8 .

As shown in Figure 3, the two end surfaces of the upper and lower stator half rings are processed into inclined surfaces as shown in the figure, and at the same time, a circular arc transition is adopted between the inclined surface and the inner ring surface of the upper and lower stator half rings. There are two main functions, one is to make the interdigital transducer processed on it avoid the working surface of the rotor; the other is to ensure that the surface acoustic wave excited by the interdigital transducer can effectively pass through the transition surface Propagate on the inner ring surface to avoid large reflection loss during surface acoustic wave propagation.

Cylindrical bosses of micron size are processed on the surface of the rotor by dry etching, and the ratio of the diameter of the bosses to the gap between the bosses is controlled between 1:4 and 1:8. The purpose of processing the boss is to: increase the contact pressure between the stator and rotor, thereby reducing the influence of air extrusion film and pollutants; the purpose of controlling the size ratio between the diameter of the boss and the gap between the boss is to reduce the acoustic surface The phase change during wave propagation is also conducive to the passage of air flow, thereby reducing air resistance.

Fig. 3 is a schematic diagram of the stator substrate and the interdigital transducers processed on the inclined surface of the stator. The structures of the upper and lower stator half rings and the upper and lower interdigital transducers are the same. As shown in FIG. 3 , the IDT designed by the power combiner type energy circulation method includes two sets of unidirectional IDTs and a power combiner 18 . As shown in Figure 3, a group of unidirectional interdigital transducers on the left are used as transmitters, and a group of unidirectional interdigital transducers on the right absorb surface acoustic waves and convert mechanical energy into electrical energy and input it to the power combiner 18, and then simultaneously The energy input by the driving power supply 14 is synthesized into one piece and then transmitted to the group of unidirectional interdigital transducers on the left. Each group of unidirectional interdigital transducers is composed of a reflective electrode and a conversion electrode, and the period length and acoustic aperture width of the two electrodes are the same. When a high-frequency electrical signal is added to the left switching electrode 10, the surface acoustic wave excited on the surface of the stator half-ring will propagate in the left and right directions of the left switching electrode 10, and the function of the left reflecting electrode 11 is to transfer the The surface acoustic wave is all reflected to the right side, and by reasonably arranging the distance between the left reflection electrode 11 and the left conversion electrode 10, the phase difference between the wave after reflection and the wave propagating to the right is 2nπ (n is an integer), then to The intensity of the wave propagating on the right is just strengthened, and when the wave propagates to the right conversion electrode 13, by the piezoelectric effect, the right conversion electrode 13 converts mechanical energy into electrical energy and enters it into the power combiner 18 through the input port marked 15, and merges The high-frequency electric signal inputted by the input terminal labeled 16 is outputted at the output terminal labeled 17 and added to the left conversion electrode 10, and so forth.

As shown in Figure 3, when the electrical signal of the sound synchronization frequency is added to the input terminal labeled 16, the high-frequency electrical signal output from the output terminal labeled 17 is added to the lower interdigital transducer 5, through the reverse pressure Due to the electric effect, surface acoustic waves are excited on the inner surface of the lower stator half-ring 4 . Similarly, the upper interdigital transducer 2 excites the surface acoustic wave on the upper stator half ring 3 opposite to that of the lower stator half ring 4 . Under the synergistic effect of the two, the rotor 1 sandwiched in the middle of the stator is in contact with the annular surfaces of the stator half-ring 3 and the stator half-ring 4 under a certain preload, and the role of the elliptical motion of the particles on the stator surface between the rotor and the stator The friction force is generated, and the friction force pushes the rotor to rotate in the direction opposite to the direction of wave propagation. By switching the drive signal, the reverse rotation of the motor can be realized.

As shown in Figure 4, when the surface acoustic waves excited on the inner annular surfaces of the entire stator half-ring 3 and stator half-ring 4 propagate in the counterclockwise direction, the particles on the surface of the stator move counterclockwise in an elliptical motion, and the stator and the rotor contact each other Generate an overall clockwise friction force, thereby pushing the rotor to rotate clockwise.

As shown in Figure 5, when the input signal is switched, when the surface acoustic waves excited by the entire stator half-ring 3 and stator half-ring 4 propagate in the clockwise direction, the surface particles of the stator move in a clockwise ellipse, and the stator and the rotor contact each other Generates a frictional force that behaves counterclockwise as a whole, thereby pushing the rotor to rotate in a counterclockwise direction. The piezoelectric single crystal lithium niobate crystal is used as the stator substrate material. The cutting of the stator and the treatment of the contact surface are very important. The cutting should ensure that the pure mode direction of the cut crystal is consistent with the wave propagation direction. The inner part of the stator half-ring The surface should be mirror finished. In addition, piezoelectric materials such as lithium tantalate and bismuth germanate may also be used. With the continuous improvement of the quality and performance of piezoelectric ceramics, the pores on the surface are greatly reduced, and they can also be used as stator substrate materials.

Claims (5)

1. a rotary sonic surface wave motor is made of stator module, interdigital transducer, rotor and bracket component, it is characterized in that:

Described stator module comprises stator semi-ring (3) and the following stator semi-ring (4) that is oppositely arranged with it, wherein goes up stator semi-ring (3) and becomes respectively by the inclined plane shape of outer ring surface to the inner ring surface indentation with following stator semi-ring (4) opposing end faces; Described rotor (1) is held on the centre by last stator semi-ring (3) and following stator semi-ring (4), and rotor (1) surface is furnished with the micron order boss;

Described bracket component comprises mount pad (6), following mount pad (7), last stator semi-ring (3) and following stator semi-ring (4) cement in respectively on the inner ring surface of mount pad (6) and following mount pad (7), and last mount pad (6) and following mount pad (7) are by spring shim (9) and hold-down bolt (8) required precompression when providing work for motor;

Described interdigital transducer comprises that upper and lower two groups of interdigital transducers are right, wherein go up interdigital transducer to (2) processing last stator semi-ring (3) up and down stator semi-rings (4) relative about on two inclined-planes, following interdigital transducer to (5) processing about relative with last stator semicircular (3) on the stator semi-ring (4) down on two inclined-planes;

Above-mentioned two groups of interdigital transducers are to being power combiner type energy circulation structure, and are specifically composed as follows:

Following interdigital transducer changes electrode (10) and left reflecting electrode (11), is placed in down the right reflecting electrode (12) on stator semi-ring (4) right tilted surface and electrode (13) is changed in right-hand rotation and power combiner (18) is formed by being placed in down left-hand rotation on stator semi-ring (4) left tilted surface (5), and the cycle of above-mentioned four electrodes is long wide all identical with sound aperture; Wherein turn left to change the port II (17) that electrode (10) connects power combiner (18), turn right and change the port I (15) that electrode (13) connects power combiner (18), driving power (14) connects the driving signal input (16) of power combiner (18);

When with port I (15) as input, port II (17) during as output, promptly left-hand rotation change add the signal of telecommunication of synchronizing frequency on the electrode (10) after, can change the left and right sides both direction propagation of electrode (10) in left-hand rotation at the surface acoustic wave of following stator semi-ring surface excitation, left side reflecting electrode (11) all reflexes to the right side to the surface acoustic wave of propagating left, it is 2n π that ripple and the original phase of wave potential difference of propagation to the right that distance between the electrode (10) satisfies after the reflection changed in left side reflecting electrode (11) and left-hand rotation, n is an integer, makes that the intensity of wave of propagating is strengthened to the right; When propagating into, ripple turns right when changing electrode (13), by piezoelectric effect, right-hand rotation is changed electrode (13) and mechanical energy is converted to the signal of telecommunication that electric energy converges the sound synchronizing frequency of driving power (14) input is input to together in the power combiner (18), be applied to once more and turn left to change on the electrode (10), by inverse piezoelectric effect, on the inner ring surface of following stator semi-ring (4), inspire surface acoustic wave;

Last interdigital transducer is similar to (5) to following interdigital transducer to (2) composition form, inspires on last stator semi-ring (3) inner ring surface and the opposite surface acoustic wave of following stator semi-ring (4) direction; Both act synergistically down, produce frictional force between rotor (1) and the stator under the effect of stator surface particle elliptic motion, and frictional force promotes rotor along the direction rotation opposite with direction of wave travel;

When during as output, promptly realizing the backward rotation of motor as input, port I (15) with port II (17).

2. rotary sonic surface wave motor according to claim 1 is characterized in that: described stator semi-ring (3) and the following stator semi-ring (4) gone up, their inclined-plane and inner ring surface are by the arc surface transition.

3. rotary sonic surface wave motor according to claim 1 and 2 is characterized in that: the micron order boss on described rotor (1) surface is a cylinder, and the ratio of the gap between boss diameter and the boss is 1: 4～1: 8.

4. rotary sonic surface wave motor according to claim 1 is characterized in that: described upward stator semi-ring (3) and following stator semi-ring (4) are monocrystalline piezoelectric material.

5. rotary sonic surface wave motor according to claim 3 is characterized in that: described rotor is silicon materials.

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