LT7097B - Piezoelectric rotary motion motor - Google Patents

Abstract

The invention is designed to create a piezoelectric rotary motion motor, which increases the speed of rotation, torque, motion precision, and expands the capabilities of the motor. The motor consists of a stator (2), made of piezoelectric bimorph plates (14), connected to a cylinder-shaped tube (15). Stator supports (11) are irreversibly attached to the mounting plates (4), while friction contacts (16) are placed on the upper and lower planes of the stator (2). Disk-shaped rotors (5, 6) pressed against friction contacts (16) are connected by a shaft (8). Rotary motion is obtained by exciting piezoelectric bimorph plates (14) with a non­harmonic sawtooth signal, thus creating a smooth rotary motion. Slits (17) in the cylinder­shaped tube (15) ensure the lowest possible stiffness of the stator (2), and the geometrical properties of the supports (11) are selected to match the bending and torsional vibration frequencies of the plezoelectric bimorph plates (14) and supports (11). To improve the precision and capabilities of the motor's motion, the non-harmonic signal is changed to a steadily rising or descending one, causing the rotors (5, 6) and shaft (8) to move proportionally to the displacements of the piezoelectric bimorph plates (14).

Description

FIELD OF THE INVENTION

This invention belongs to the fields of electro-mechanical, mechatronic systems and robotics. The concept, design, construction and operation principles of the piezoelectric motor can be applied to the development of small volume, high precision rotary motion actuators for controlling the angular position of optical devices such as lenses, mirrors or optical filters. Positioning or other high-precision motion actuators developed using this piezoelectric motor are applicable for controlling, determining and adjusting the angular position of the laser beam, test specimen or other objects in a continuous cycle.

STATE OF THE ART

The use of high-precision laser and other optical systems in various fields of industry, medicine or scientific research allows to improve the results of these fields of activity, increase the accuracy and quality of devices and promotes sustainable development. However, with the rapid development of these fields, the need for extremely accurate control and adjustment of the angular position of optical systems, lenses, mirrors, test specimens or other objects is increasing. In order to meet this need, piezoelectric actuators, motors and actuators are used, which can ensure proper object positioning accuracy and repeatability. Several technical solutions and patents are currently known that offer solutions to these technical problems.

Patent CN109861582A describes an inertial, rotary motion piezoelectric motor consisting of a rectangular base with a cylindrical cavity. The motor axis is installed in the cavity, through the force of friction, on which an irregularly shaped rectangular rotor is mounted, which is spring-loaded to the axis. One or more bimorphic piezoelectric plates are attached to the rotor, and weights are mounted on their free ends. Exciting the bimorph piezoelectric plates with a saw-tooth signal whose frequency is equal to or close to the frequency of the first bending deformation mode of the plates results in a rotary motion of the rotor. Rotational speed and torque are increased using the asymmetry of the rotor and weights, which ensure the shock-inertial principle of operation of the motor. By changing the mass of the weights, the asymmetry of the rotor or the number of plates, the maximum speed and torque of the motor can be changed.

Patent CN203491927U describes an inertial, rotary motion motor consisting of four bimorph piezoelectric plates attached to the motor stator, with weights attached to the free ends of the plates. The motor stator is anchored to the motor base using Z-shaped anchoring structures, and the disk-shaped rotor is placed on the upper part of the stator. The rotor, relative to the stator, is centered with the help of a stepped shaft, which is anchored in the stator through frictional force, and is connected to the rotor through a rolling bearing. The rotational movement of the disk-shaped rotor is obtained by the inertial-shock principle by exciting the piezoelectric bimorph plates with a harmonic signal whose frequency is equal to or close to the first mode of plate bending deformations. The inertial-impact principle of motor operation is obtained due to the installation of piezoelectric bimorph plates in relation to the vertical axis of the motor, i.e. the plates are mounted inclined with respect to this axis, as a result of which a tangential impact to the stator is ensured during the oscillations, the force amplitude of which is amplified by the weights installed at the free ends of these plates, while inertial vibrations are obtained due to the asymmetric anchoring of these plates in the stator. Motor speed and torque can be adjusted by changing the friction force between the stator and the rotor, by increasing or decreasing the excitation signal amplitudes, and by changing the weights.

Patent CN112953297A describes the design of a piezoelectric inertial rotary motion motor consisting of two active T-shaped bimorph piezoelectric plates and two passive T-shaped plates made of elastic material. Passive and active plates are connected to each other by applying a connecting cylinder, distributing these plates evenly around the vertical axis of this cylinder, and connecting them permanently to the outer surface of the cylinder. At the ends of the upper and lower plates, non-dismantling, weights are mounted to form the motor stator. The stator is placed on a disk-shaped rotor, and the rotary motion of the rotor is obtained by exciting the bimorph piezoelectric plates with a non-harmonic sawtooth signal with a frequency equal to or close to the first mode of vibration of the plates. When stimulating the motor with a saw-shaped electrical signal, the plates are deformed at different speeds, i.e. when the excitation voltage signal increases steadily, the static friction force between the stator and the rotor is greater than the inertia force of the rotor, so the rotor moves together with the stator until the excitation signal reaches its maximum value. Then the value of the signal suddenly drops to the minimum value, as a result of which the direction and speed of deformation of the plates change to the opposite and the force created by the plates exceeds the static friction force between the stator and the rotor and thus creates a slip between them. By repeating the described process, the rotary motion of the rotor is obtained. In order to increase the speed and torque of the rotor, the number of bimorph piezoelectric plates or the amplitude of the excitation signal can be increased.

ESSENCE OF THE INVENTION

The essence and purpose of the invention is to increase the rotational speed, torque, and accuracy of the angular movement of the piezoelectric rotary motion motor, as well as to expand the functional possibilities.

The purpose of the invention is achieved by the fact that the rotary motion piezoelectric motor consists of a stator, which consists of three piezoelectric bimorph plates evenly arranged around the vertical axis of an elastic cylindrical tube, and three slits are formed in the cylindrical tube, which are placed between the piezoelectric plates thus forming the stator. Friction contacts are placed on the top and bottom planes of each piezoelectric bimorph plate. Two disc-shaped rotors are spring-loaded against these contacts. One rotor is pressed against the contacts located on the upper surface of the bimorph plate, the other rotor - against the lower surface. The pressing force of the rotors is changed by setting the compression of the spring, which is mounted on the upper disk-shaped rotor. The stator is fixed in the housing using cylindrical anchoring supports, which are mounted on the upper and lower planes of the bimorph plates.

The rotation speed and torque of the motor are increased when an asymmetric periodic electrical signal whose frequency is equal to or close to the first resonance frequency of the bending vibrations of the piezoelectric bimorph plates excites the bending deformations of the plates, the amplitudes of which are increased with the help of notches formed in the cylindrical tube. The geometric properties of the slots are selected to ensure the lowest possible stiffness of the entire stator. The rotation speed of the motor is also increased when the friction contacts are placed on the upper and lower planes of the piezoelectric bimorph plates so that their attachment points coincide with the zone of maximum displacements of the bending vibrations of the bimorph plate, and the positions of the cylindrical supports of the stator are selected so that their vertical axes coincide with the first piezoelectric plates. vibration modes of bimorphic plates in nodal zones, and their length and diameter should be such that the resonant frequency of the first mode of torsional vibrations of the supports coincides with the resonant frequency of the first mode of bending vibrations of piezoelectric bimorphic plates.

The accuracy of the angular movement of the motor is improved when an AC or DC electrical signal is used for excitation, which creates oscillations of the piezoelectric bimorph plates, which are transmitted to the disc-shaped rotors through frictional contacts, thus creating a high-precision rotor rotation.

DESCRIPTION OF DRAWINGS

The figures in the drawings are provided as an indication of the possible implementation of the invention and are not intended to limit the scope of the invention. None of the drawings and graphs presented should be considered as limiting, but only as examples of possible embodiments of the invention.

Fig. 1 a, b Principle diagram of a piezoelectric rotary motion motor:

(a) - isometric view of a piezoelectric rotary motion motor;

(b) - exploded view of the piezoelectric rotary motion motor;

Fig. 2 a,b Basic diagram of the stator of the piezoelectric rotary motion motor:

(a) - isometric view of the stator of a piezoelectric rotary motion motor;

(b) - exploded view of the piezoelectric rotary motion motor stator;

Fig. 3 Piezoelectric rotary motion motor excitation scheme;

Fig. 4 Oscillation mode of piezoelectric rotary motion motor.

Designation of the elements shown in the drawings:

- stiffness support;

- motor stator;

—fixing screw;

— mounting plate;

- lower disc-shaped rotor;

- upper disc-shaped rotor;

- compression spring;

- axis;

- spring retainer;

- fixing bolt;

- stator supports;

- piezoelectric plate;

- elastic plate;

- piezoelectric bimorph plate;

- flexible cylindrical tube;

- frictional contact;

- notch;

- signal generator;

- polarization direction of the piezoelectric plate.

DETAILED DESCRIPTION OF THE INVENTION

The actuators are described hereafter with reference to the drawings, but the technical implementation of the motor is not limited to the ways presented. Various modifications and improvements of implementation methods are possible.

Detailed description: The piezoelectric rotary motion motor consists of a motor stator (2) consisting of three piezoelectric bimorph plates (14), consisting of piezoelectric plates (12), polarized in the direction of thickness and permanently fixed on elastic plates (13). Piezoelectric bimorph plates (14) are connected to each other by means of an elastic cylindrical tube (15) ensuring the same radial arrangement of piezoelectric bimorphic plates (14) with respect to the vertical axis of the cylindrical tube (15), and notches (17) are formed in the cylindrical tube itself. Stator supports (11) are permanently placed at the free ends of the piezoelectric bimorph plates (14), the position of which is chosen to coincide with the nodal zones of the first bending vibration mode of the piezoelectric bimorph plates (14). Frictional contacts (16) are permanently placed on the upper and lower planes of the stator (2), the positions of which are chosen so that their vertical axes coincide with the pulses of the first bending vibration mode of the piezoelectric bimorph plates (14). The motor stator (2) is anchored using stator supports (11), the free ends of which are permanently connected to the motor stator anchoring plates (4). In order to increase the rigidity of the entire structure, the supports (1) are demountably anchored between the stator anchoring plates (4) using anchoring screws (3). The disk-shaped rotors (5, 6) are placed on the upper and lower friction contacts (16) and are connected to each other by an axis (8), which is placed through the central cavity of the motor stator (2) thus centering the disk-shaped rotors (5,6) on the friction contacts (16) ) in relation to The lower disk-shaped rotor (5) is connected to the axis (8) without disassembly, while the upper disk-shaped rotor (6) is connected to the axis (8) through frictional force. The compression spring (7) is placed on the upper disk-shaped rotor (6), and the spring retainer (9) is put on the axis (8) fixing its vertical position with the fixing screws of the retainer (10), thus ensuring the necessary pressing force between the disc-shaped rotors (5, 6) ) and friction contacts (16).

Description of the operation of the piezoelectric motor: The rotary motion of the rotors (5, 6) is excited when a non-harmonic asymmetric saw-tooth electric signal is supplied from the signal generator (18) to the piezoelectric bimorphic plates (14) with a frequency equal to or close to the first bending oscillation of the piezoelectric bimorphic plates (14) for the resonant frequency of the mode. As the voltage value increases evenly, the piezoelectric bimorph plates (14) are uniformly deformed and at the same time generate a displacement of the friction contacts, which, due to the static friction force between the friction contacts (16) and the disc-shaped rotors (5, 6), create an angular disc-shaped rotor (5, 6) and axis (8) displacement. After the voltage reaches the maximum value, it begins to decrease sharply until it reaches the minimum value and at the same time the piezoelectric bimorph plates (14) are deformed in the opposite direction, but at a higher speed, so the friction force between the disk-shaped rotors (5, 6) and the friction contacts (16) decreases and the frictional contacts (16) slip on the surfaces of the rotors (5,6) and the rotary movement of the rotors (5, 6) and the axis (8) is not created. By repeating the steps described above, a uniform rotational movement of the rotors (5,6) and the axis (8) is created. Rotational motion in the opposite direction is obtained when the phase of an electric inharmonic sawtooth signal is changed by 180 degrees. When the signal generator (18) to the piezoelectric bimorph plates (14) to a uniformly rising or falling electrical signal, the piezoelectric bimorph plates (14) bend in the direction of polarization (19) of the piezoelectric plates (12). The displacement amplitude is directly proportional to the signal amplitude, and the force generated by the piezoelectric bimorph plates (14) does not exceed the static friction force between the disk-shaped rotors (5, 6) and the friction contacts (16). 8) the displacement is directly proportional to the displacement of the frictional contacts (16) of the piezoelectric bimorph plates (14). In order to obtain the angular displacement of the disk-shaped rotors (5, 6) and the axis (8) in the opposite direction, the phase of the electrical signal is changed to the opposite.

Claims (5)

DEFINITION OF THE INVENTION 1. Piezoelectric rotary motion motor, including a stator (2) consisting of piezoelectric bimorph plates (14) connected to each other by a cylindrical tube (15), friction contacts (16) mounted on the upper and lower planes of the stator (2), stator supports ( 11) and disk-shaped rotors (5, 6) and axis (8) differ in that notches (17) are formed in the cylindrical tube (15), the number of holes in the tube is chosen to be equal to the number of piezoelectric bimorph plates (14). 2. Motor according to claim 1, characterized in that the geometrical characteristics of the notch (17) are selected in such a way as to ensure the smallest possible structural rigidity of the stator (2), but without affecting the thickness of the elastic plates (13). 3. Motor according to claim 1, characterized in that the length and thickness of the stator supports (11) are selected so that the first mode frequency of their torsional vibrations coincides with the resonant frequency of the first mode of bending vibrations of the piezoelectric bimorph plate (14). 4. A motor according to claim 1, characterized in that the mounting location of the stator supports (11) on the upper and lower planes of the piezoelectric bimorph plate (14) is selected to coincide with the nodal zone of the first mode of its bending vibrations. 5. Motor according to claim 1, characterized in that the location of the frictional contacts (16) on the piezoelectric bimorph plates (14) is selected to coincide with the pulse of the first bending vibration mode of the piezoelectric bimorph plates (14).