RU2181522C2 - Piezoelectric linear stepping motor - Google Patents

Abstract

FIELD: servo mechanisms. SUBSTANCE: motor has frame accommodating locking assemblies and moving part. Locking assemblies are, essentially, assemblies of at least two piezoelectric units arranged in tandem in longitudinal plane. Each piezoelectric unit has shifting piezoid and locking piezoid which are isolated from each other as well as from frame and friction member by means of insulators. Moving part has at least one guide that enters respective guide on friction members provided with slits. Clearances between piezoelectric units are filled with flexible insulating material. EFFECT: enhanced precision and force. 2 cl, 16 dwg

Description

 The invention relates to the field of electric motors, and more specifically relates to piezoelectric linear stepper motors, and can be used as an actuator in electrical engineering, telemechanics, radio engineering and automation.

 A linear motor is known that contains a guide, a housing and a mover in the form of plates mounted at an angle in the housing and frictionally interacting with the guide (USSR Author's Certificate 801149, MKI H 01 L 41/02).

 However, this linear motor has large overall dimensions and weight, carries out movement with the help of elastic plates, while it is impossible to obtain great efforts and ensure positioning accuracy.

 A known piezoelectric linear stepper motor comprising a housing with fixing nodes fixed therein and a movable part with a working element (USSR Author's Certificate 720576, MKI H 01 L 41/04).

 However, this engine has a number of disadvantages: a greater number of parts, design complexity, the complexity of manufacturing the locking assemblies and the ability to rotate the movable part in the process of linear movement.

 The closest analogue to the claimed invention is a piezoelectric linear stepper motor, comprising a housing with fixing nodes fixed therein, made of at least two piezoblocks arranged in a longitudinal plane one after another, and a movable part, each piezoelectric block consisting of a shifting piezoelectric element fixing piezoelectric element and friction element (USSR Author's Certificate 502426, H 02 N 2/04, 04/19/1976).

 However, this engine has low accuracy of pitch and effort on the working element of the engine and low accuracy of positioning of the moving part.

 The basis of the present invention was the task of creating a piezoelectric linear stepper motor, the constructive implementation of which would improve the synchronization of the work of the piezoelectric elements when they are shifted and increase the accuracy of the step and force on the working element of the engine, as well as improve the accuracy of positioning of the moving part.

 This is achieved by the fact that in a piezoelectric linear stepper motor comprising a housing with fixing assemblies fixed therein, made of at least two piezoblocks arranged in a longitudinal plane one after another, and a movable part, each piezoelectric block consisting of a shear piezoelectric element fixing the piezoelectric element and the friction element, according to the invention, the biasing element and the locking element are separated relative to each other, the housing and the friction element by insulators, while the movable part has at least one guide, which is included in the corresponding guide on the friction elements, and the gaps between the piezo blocks are filled with elastic insulating material.

 Piezoelectric elements can be made in the form of a package of piezoelectric plates, rings or their sectors, the electrodes of which are connected in parallel through one, while the polarization direction of each subsequent piezoelectric plate, ring or sector is directed in the opposite direction from the previous one.

The invention is further illustrated by the description of specific examples of its implementation with reference to the accompanying drawings, in which:
FIG. 1 shows a piezoelectric linear stepper motor (first embodiment), front view;
figure 2 is the same, a longitudinal section;
figure 3 - the second embodiment of the engine, front view;
figure 4 is the same, a longitudinal section;
5 is a third embodiment of the engine, front view;
6 is the same, longitudinal section;
7 is a fourth embodiment of the engine, front view;
Fig.8 is the same, longitudinal section;
FIG. 9-16 - cycles of the piezoelectric linear stepper motor.

 The piezoelectric linear stepper motor comprises a cylindrical housing 1 (Figs. 1 and 2), in which two piezoblocks 2 and 3 are located, and a movable part in the form of a cylindrical rod. Piezo blocks 2 and 3 are rigidly attached to the inner surface of the cylindrical body 1. Each piezo block 2 and 3, respectively, consists of a connected piezoelectric element 5, a fixing piezoelectric element 6, insulators 7 and a friction element 8. Each shear piezoelectric element 5 has an initial polarization vector directed under angle to the longitudinal axis of the engine. The fixing piezoelectric elements 6 have an initial polarization vector directed perpendicular to the longitudinal axis of the engine. The insulators 7 provide isolation of the shear and the fixing piezoelectric element relative to each other, as well as relative to the housing 1 and the friction element 8. The friction element 8 is made split to provide a more tight compression of the movable part 4 of the piezo blocks 2 and 3.

 Each piezoelectric element has electrodes to which wires are connected (these elements are not shown in the drawing).

 The gaps between the piezo blocks 2 and 3 are filled with elastic insulating material 9.

 A guide 10 is made on the surface of the movable part 4, which enters the corresponding guide on the friction element 8. The guide 10 eliminates the possibility of radial displacement of the cylindrical rod.

 Other versions of the piezoelectric linear stepper motor are possible.

 In the second embodiment (FIGS. 3 and 4), in contrast to the first piezo blocks 2 and 3 are located in the same transverse plane and are made in the form of sectors. This reduces the weight and overall dimensions of the engine.

 The third option (Figs. 5 and 6) differs from the first in the shape of the housing, the movable part, and the simpler construction of piezoelectric elements and piezoelectric blocks in manufacturing. The housing 11 has the shape of a parallelepiped, and the movable part is made in the form of a rod 12 of rectangular cross-section.

 In the fourth embodiment (FIGS. 7 and 8), the housing 14 has a cutout 15 through which the movable part 16 extends beyond the housing. The design of the piezo blocks is similar to the third option.

 The engine operates as follows.

 Piezo blocks 2 (Fig. 9) and 3 are made of the same shifting piezoelectric elements 5 and fixing piezoelectric elements 6. The operation of piezoelectric blocks 2 and 3 is carried out by applying voltage of the corresponding polarity to the piezoelectric electrodes. When applying bias piezoelectric elements 5 to the electrodes of positive voltage due to the inverse piezoelectric effect, the inner part shifts to the left relative to the external part fixed in the housing 1. When applying positive voltage to the fixing piezoelectric elements 6, they clamp the movable part 4, because their polarization vector is directed perpendicular to the longitudinal axis of the engine. When a negative voltage is applied, the opposite effect occurs: the shifting piezoelectric elements 5 are shifted to the right, and the fixing piezoelectric elements 6 are squeezed from the movable part 4.

 The duty cycle consists of six cycles.

 The position corresponding to the first measure is shown in FIG. 9. A positive voltage is applied to the shifting piezoelectric element 5 of the piezoblock 2 and the fixing piezoelectric elements 6 of the piezoblocks 2 and 3, and a negative voltage is applied to the shifting piezoelectric element 5 of the piezoelectric block 3. In this case, the shifting piezoelectric element 5 of the piezoblock 3 is shifted to the right, and the shifting piezoelectric element 5 of the piezoblock 2 is shifted to the left, the fixing piezoelectric elements 6 of both piezoelectric blocks clamp the movable part 4 through the friction elements 8.

 In the second cycle (Fig. 10), a negative voltage is applied to the fixing piezoelectric element 6 of the piezoblock 3, while it is wrung out from the movable part 4.

 In the third step (Fig. 11), a negative voltage is applied to the shifting piezoelectric element 5 of the piezoelectric block 2 and it moves to the right and moves the fixing piezoelectric element 6 and the movable part 4 by one step. At the same time, a positive voltage is applied to the shifting piezoelectric element 5 of the piezoelectric block 3 and it is shifted to the left together with the fixing piezoelectric element 6.

 In the fourth step (Fig. 12), a positive voltage is applied to the fixing piezoelectric element 6 of the piezoelectric unit 3, which compresses the movable part 4.

 In the fifth step (Fig. 13), a negative voltage is applied to the fixing piezoelectric element 6 of the piezoblock 2 and it is wrung out from the movable part 4.

 In the sixth cycle (Fig. 14), the piezo blocks 2 and 3 diverge, i.e. A positive voltage is applied to the electrodes of the shifting piezoelectric element 5 of the piezoelectric block 2 and it is shifted to the left, and a negative voltage is applied to the shifting piezoelectric element 5 of the piezoelectric block 3 and it, together with the fixing piezoelectric element 6 and the movable part 4, is shifted to the right. The moving part 4 is moving one more step. This completes the work cycle, the moving part has moved two steps.

 Further, the linear displacement process continues in the same sequence.

 To reverse, it is necessary to change the order of the voltage supply to the fixing piezoelectric elements. The use of several sequentially installed piezo blocks will significantly increase the force on the moving part.

 The proposed piezoelectric linear stepper motor has a simple design and manufacturing technology, small overall dimensions and weight, a large force on the moving part, and also improves positioning accuracy and uniformity of linear movement.

Claims (2)

 1. A piezoelectric linear stepper motor, comprising a housing with fixing assemblies fixed therein, made of at least two piezoblocks arranged in a longitudinal plane one after another, and a movable part, each piezoblock consisting of a shear piezoelectric element, a fixing piezoelectric element and a friction element, characterized in that the shear piezoelectric element and the fixing piezoelectric element are separated from each other, the housing and the friction element by insulators, while the movable part has at least one guide, which is included in the corresponding guide on the friction elements, and the gaps between the piezo blocks are filled with elastic insulating material.  2. The piezoelectric linear stepper motor according to claim 1, characterized in that the piezoelectric elements are made in the form of a package of piezoelectric plates, rings or their sectors, the electrodes of which are connected in parallel through one, while the direction of polarization of each subsequent piezoelectric plate, ring or sector is directed to the opposite side from the previous one.

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