LT6915B - FLAT SPEED PIEZOELECTRIC MOTOR - Google Patents

Abstract

The invention is intended to provide a high-speed piezoelectric motor with an increased shaft rotation speed, ensuring the reliability of the drive rotor contact, and expanding its functionality: the use of two rotors rotating in opposite directions and the reduction of the motor supply voltage. The invention, like the analogue, can be applied very efficiently in the development of drives for micromotors. The piezoelectric motor consists of a flat-shaped radial oscillation actuator made of two concentric rings tightly connected to each other by lamellae. The slats point at an acute angle to the rotor. The flat part of the larger diameter ring is connected by a thin piezoceramic disk polarized according to its thickness. The lamella zone is made in the form of a convex hollow circular cone: the convex angle does not exceed 30 degrees. The smaller diameter flat part of the actuator slides in contact with the spring-loaded rotor. By attaching an additional actuator with a convex lamellar zone to the other (free) flat part of the piezoelectric reflection in a concentric mirror reflection so that the lamellae directions of both actuators coincide, it is possible to rotate two rotors connected to one shaft. It is possible to obtain two axial rotations in opposite directions from the motor if actuators with opposite lamellae directions are glued to said piezoelectric element. The sprung rotors will rotate in opposite directions, which expands the functionality of the motor. In order to increase the power of the piezoelectric device and to reduce the supply voltage, two additional piezoelectric elements are glued to said actuators so that their polarization directions are opposite to the direction of the piezoelectric element between the actuators.

Description

Technical field:

The present invention belongs to the class of piezoelectric motors. The invention can be applied very effectively in the development of high-speed, reliable multifunctional drives of small dimensions and weight, which is especially relevant for microscopes (microdrons), gyroscopes - stabilizers, etc. technicians.

State of the art:

With the rapid development of computer technology, the information processing and control bodies of mechatronic devices are becoming miniature and significantly surpass the performance bodies in terms of weight and dimensions, the work of which is based on the use of classic electric motors. One of the directions of research in order to reduce the gap between the computer and mechanical part of mechatronic devices is the development of a fundamentally new type of machine - piezoelectric motors, in which the rotor is rotated not by the interaction of electromagnetic fields, but by oriented ultrasonic frequency oscillations. At present, the development of high-speed mechatronic devices, such as flying or floating microrobots, is focusing on the development of small-sized, high-speed high-speed engines.

A known piezoelectric motor is described in U.S. Pat. No. 4,019,073 B2 (1977), the rotor of which is rotated by radial oscillations excited by a piezoceramic ring and transmitted to the rotor by means of sprung vanes. Here the lamellae are used to perform a dual function: the transmission of vibrations to the area of contact with the rotor and the role of the spring. This limits the increase in engine power, as the transfer of higher energy from the piezoelectric element is limited by increasing the thickness of the flexible lamellae. In addition, the reliability of the motor is limited by the unevenness of the individual lamellae in contact with the rotor.

In U.S. Pat. No. 4,959,580 B2 (1990), the same author proposes a modernized method of attaching lamellas to increase motor power by soldering them to piezoceramic disc electrodes. This slightly increases the power, but does not solve the problems of low reliability.

U.S. Pat. No. 4,884,002 B2 (1989) proposes to expand the number of lamellae by grouping them in order, and U.S. Pat. No. 7,105,987 B2 (2006) proposes to modify the lamella configurations. However, the contact zone remains basically the same - a number of individual points, which does not solve the problems of engine reliability, especially high-speed engines.

In the U.S. Pat. The radial oscillations of the piezoelectric ring are transformed into rotor rotation by means of lamellae. By gluing the same actuator to another flat surface of the piezoelectric ring and springing an additional rotor to its lamellae, the rotation of the other rotor in the opposite direction can be obtained. Although the proposed patent extends the functionality of the engine, the contact zone remains basically the same - a number of individual points, which does not solve the problems of engine reliability, especially in the case of high-speed engines.

The closest technical invention to the present invention is the piezoelectric motor described in patent LT 6636 B2 H01L41 / 00 (2019). The piezoelectric motor consists of a radial oscillation actuator with the lamella wires tightly connected to the inner radial portion directed at an acute angle to the conical surface of the rotor and the other ends of the lamella waveguides tightly connected to the outer radial annular cylindrical portion. One flat side of the actuator is connected to a piezoelectric transducer, e.g. a thin piezoceramic disk polarized according to its thickness. By attaching an additional piezoelectric element to another plane of the actuator, we obtain a reversible piezoelectric motor, which significantly expands its application possibilities. An additional rotor is sprung on the other side of the cylindrical ring to extract two axial rotations in opposite directions from the motor. Both rotors have the ability to rotate in opposite directions without additional means. Although the piezo motor according to the proposed patent is simple in terms of production, it works reliably at several thousand rpm, but two modes of actuator oscillation are used for its stable operation, which complicates the development of the motor power supply and control system.

The aim of the invention is to increase the rotational speed of the piezoelectric shaft, its power, stability and reliability of operation, and to expand its functional applicability.

The first objective: to increase the speed, stability and reliability of the motor is achieved by a piezoelectric motor consisting of a flat radial vibration actuator consisting of two concentric rings tightly connected by lamellae pointed at an acute angle to the rotor and a larger diameter ring. with a thin piezoelectric element, the lamellar zone of the flat actuator is made convex in the form of a hollow circular cone and the convex angle does not exceed 30 degrees. The rotational speed of the piezoelectric shaft increases the stability and reliability of the operation due to the fact that the actuator is excited in only one mode - radial, and the rotor is rotated on a flat surface of the concentric ring of the actuator.

The second goal: the increase in motor power is achieved by gluing to the other (free) flat part of the piezoelectric reflector an additional actuator with a convex lamellar zone so that the lamellae directions of both actuators coincide, it is possible to rotate two rotors connected to one shaft, i. increase engine power.

If actuators with opposite lamellae directions are attached to said piezoelectric element, it is possible to extract two axial rotations in opposite directions from the motor, the spring-loaded rotors will rotate in opposite directions, which expands the functional possibilities of the motor.

The third objective is to further increase the speed of the piezoelectric motor and to reduce the supply voltage by gluing two additional piezoelectric elements to said actuators so that their polarization directions are in the opposite direction to the piezoelectric element between the actuators.

The following drawings are provided to illustrate the invention:

FIG. 1 - the schematic diagram of a piezoelectric motor is shown; FIG. 2 actuator image; FIG. 3 - piezoelectric motor design; FIG. 4 is a view illustrating the possibility of using a second rotor; FIG. 5 is a view illustrating the arrangement of the slats; FIG. 6 - cross-section of a piezoelectric motor rotating two shafts of two rotors; FIG. 7 - section of a piezoelectric motor in opposite directions of rotation of two shafts; FIG. 8 is a view of the two-shaft motor illustrating the arrangement of the slats; FIG. 9 - section of low supply voltage piezo motor; FIG. 10 - Diagram of piezoelectric connection and "two-generator" piezoelectric motor.

a detailed description of the device.

The piezoelectric motor (Fig. 1-3) consists of a flat-shaped radial oscillation actuator (1) consisting of two concentric rings (2) (3) tightly connected to each other by lamellae (4) directed at an acute angle to the rotor (5). The flat part of the larger diameter concentric ring (2) is connected to a thin ring-shaped piezoelectric element (6), the electrodes of which are electrically connected to a generator with an output voltage UI. The lamellar zone of the flat actuator is made in the form of a convex hollow circular cone (7). The experiment found that the convex angle (8) did not exceed 30 degrees. The smaller diameter flat part (3) of the actuator slides into contact with the spring force (P) of the rotor (5). The actuator (1) is mounted in the housing (11). The motor shaft (13) rotates in the bearing (14) and is connected to the rotor (5). In order to prevent the energy of the radial oscillations of the actuator from being transferred to the housing (11), a pendulum (9) is introduced between them. The peripheral part of the actuator, pierced, for example, by laser, is used to form the spring (9).

The rotational speed, stability and reliability of the piezoelectric motor shaft are increased due to the fact that the actuator is excited in only one mode - radial, and the rotor (5) is rotated on the flat surface of the concentric ring (3) of the actuator.

The power of the piezo motor can be increased by turning the shaft with two actuators. This is achieved (Fig. 4-6) by gluing an additional actuator (14) with a convex lamellar zone to the other (free) flat part of the piezoelectric element (6) with a convex lamellar zone so that the lamellae directions of both actuators coincide. It is possible to rotate the two rotors (5) connected to one shaft (13) and thereby increase the engine power.

In order to obtain two axial rotations in opposite directions from the motor, the actuators (1) and (14) must be glued to said piezoelectric element (6) in such a way that their lamellae directions are opposite. The spring-loaded rotors (5) will rotate in opposite directions, which expands the functionality of the motor.

For many applications of piezoelectric motors, e.g. when used in microcircuits, the autonomous power supply requires an extremely low voltage value. To reduce the voltage of the motor power supply, a piezoelectric motor consisting of two separate actuators (1) should be constructed, attached separately to the motor housing (11) and fed separately from the two generators (UI and U2), as shown, for example, in FIG. 9). In this case, additional problems arise: the centering of the actuator axes, and when attaching them, another - an additional power supply U2.

This is achieved (Fig.10) by gluing two additional piezoelectric elements (15) to said actuators (1) and (14) so that their polarization directions (p) are opposite to the direction of the piezoelectric element (6) between actuators (1) and (14). ). Using such a combination of elements, we obtain a homogeneous resonant vibrating system of three piezoelectric elements (6-15-15) glued to two actuators (1-14).

Operation of a flat - speed piezoelectric motor. By applying a resonant voltage (UI) of the radial oscillations to the electrode of the piezoelectric element (6) of the actuator (1), the radial oscillations in the direction “a” are excited in the concentric ring (2) of the actuator. The radial oscillations in the ring (2) cause longitudinal vibrations of the lamellae (4) (direction "b"). Since the lamellae (4) are connected to the concentric rings (2) and (3) at an acute angle, they vibrate to create rotational oscillations of the concentric ring (3) of the actuator (direction “c”). Since the lamellar zone is made in the form of a convex hollow circular cone (8), the radial oscillations of the actuator are additionally transformed into in-phase oscillations of the concentric ring (3) perpendicular to its plane (direction 'd').

In this way, the rotor (5), acting on a smaller diameter ring (3), receives high-frequency vibrations of vertical displacement (c) - rotation (d), which causes it to rotate intensively.

The operation of a motor with a shaft (Fig. 4-6) or two shafts with opposite directions rotated by two actuators (Fig. 7-8) is analogous: by feeding the electrodes of the piezoelectric element (6) through electrically and mechanically connected (glued) actuator (1) resonant voltage (UI) of radial oscillations, radial oscillations in the concentric rings (2) of the actuator concentric rings (2), which induce longitudinal vibrations of the lamellae (4) (direction “b”) and rotational oscillations of the concentric rings (direction) (direction) "C") and vertical oscillations perpendicular to the plane of the rings (direction "d").

These problems are easily solved by using a composite homogeneous actuator instead of two actuators. The proposed design (Fig.10) allows two actuators to be glued together into one homogeneous resonant system. The polarization directions "p" of the piezoelectric elements are arranged in such a way that the mode of radial oscillations in the homogeneous design of the obtained actuator is excited by applying a resonant frequency voltage UI to the electrodes. Thus, the reduction of the supply voltage is obtained due to the connection of the three piezoelectric elements and the possibility of their synchronous supply.

Claims (3)

A flat-speed piezoelectric motor consisting of a flat-shaped radial oscillation actuator consisting of two concentric rings tightly connected to each other by lamellae directed at an acute angle to the rotor, the flat part of the larger diameter ring being connected to a thin piezoelectric ring, stability and reliability of operation, the lamellar zone of the flat actuator is made in the form of a convex hollow circular cone, and the angle of convexity does not exceed 30 degrees. A flat-speed high-speed piezoelectric motor according to claim 1, characterized in that an additional actuator with a convex lamellar zone is glued to the free flat part of said piezoelectric concentrically to increase the power of the motor so as to direct the lamellae of both actuators. A flat-speed piezoelectric motor according to claims 1 and 2, characterized in that in order to increase the rotation speed of the motor shaft and reduce the supply voltage, two additional piezoelectric elements are attached to said actuators so that their polarization directions are opposite to each other.