CN111464070A

CN111464070A - Linear ultrasonic motor stator and electric excitation method thereof

Info

Publication number: CN111464070A
Application number: CN202010198201.2A
Authority: CN
Inventors: 曲建俊; 曲华杰; 温众普
Original assignee: Harbin Institute of Technology
Current assignee: Harbin Institute of Technology
Priority date: 2020-03-19
Filing date: 2020-03-19
Publication date: 2020-07-28
Anticipated expiration: 2040-03-19
Also published as: CN111464070B

Abstract

A linear ultrasonic motor stator and its electric excitation method, the stator includes stator elastomer and piezoelectric ceramic wafer; an open slot is cut on the stator elastic body along the length direction, and the stator elastic body is divided into a driving body and two symmetrical driving legs by the open slot; two opposite outer side surfaces of the two driving legs are adhered with piezoelectric ceramic plates in axial symmetry, and the upper ends of the two driving legs are respectively provided with driving feet extending outwards; all the piezoelectric ceramic sheets are coated with electrode layers. The method of electrical stimulation comprises: 1) bonding a piezoelectric ceramic plate; 2) making an electrified electrode; 3) two paths of same-frequency sinusoidal voltage signals are used for exciting local second-order bending vibration of the driving legs and integral first-order longitudinal vibration of the stator at the same time, and forward and reverse movement of the driving rotor is finally achieved. The invention realizes the elliptic vibration of the driving feet by utilizing the combination degeneration of the local second-order bending vibration of the two driving legs of the stator and the integral first-order longitudinal vibration of the stator.

Description

Linear ultrasonic motor stator and electric excitation method thereof

Technical Field

The present invention relates to an ultrasonic motor and an electric excitation method, and more particularly, to a stator of a linear ultrasonic motor and an electric excitation method thereof.

Background

The ultrasonic motor converts electric energy into vibration energy of the stator by utilizing the inverse piezoelectric effect of a piezoelectric material, excites elliptical or oblique arc line vibration at the end point of a driving foot of the stator, and converts the vibration energy into rotation or linear motion of a moving part through contact friction. Compared with the traditional electromagnetic motor, the ultrasonic motor has the advantages of low speed, large output of force, quiet and noiseless operation, flexible design, compact structure, high energy density, easy miniaturization and the like.

The stator is the core component of the ultrasonic motor, and for the linear ultrasonic motor, the stator structure mainly has a flat plate shape and a few slender cylindrical structures. The stator can drive the rotor to move because the elliptical vibration is excited at the driving foot end of the stator, the elliptical vibration is usually synthesized by two paths of vibration, various excitation vibration and driving methods exist at present, the excitation vibration and the driving methods can be divided into two paths of vibration with the same frequency driving and two paths of vibration with different frequencies driving, and the vibration combination can be divided into longitudinal and longitudinal vibration combinations, longitudinal and bending vibration combinations, bending vibration combinations and the like. The publication No. CN1359188A proposes a bending-longitudinal combined linear ultrasonic motor vibrator which is a cylindrical structure, by means of a d33 mode of piezoelectric ceramics, the combination of 1-order longitudinal vibration and 2-order bending vibration of the whole cylindrical vibrator is utilized to enable convex teeth at the end part of the vibrator to generate elliptical vibration, and the cylindrical structure limits the size of the vibrator to be further reduced; the publication No. CN1327301A proposes a longitudinal and bending combined linear ultrasonic motor vibrator, which is a square plate structure, by means of a d31 mode of piezoelectric ceramics, the combination of 1-order longitudinal vibration and 2-order bending vibration of the whole square plate vibrator is utilized to make the protrusion at the end part of the vibrator vibrate elliptically, and the square plate structure determines that the vibrator is not suitable for fixing and needs a special pre-tightening mechanism; CN1235404A discloses a linear motor driving vibrator, which is a cylinder and square plate combined structure, and excites the integral longitudinal vibration of the cylinder and square plate combined structure by means of a d33 mode of piezoelectric ceramics, and excites the integral bending vibration of the square plate and cylinder combined structure by means of a d31 mode of the piezoelectric ceramics, so that teeth at the end part of the vibrator generate elliptical vibration, and the vibrator is long and difficult to miniaturize in order to degenerate 2-order bending vibration and 1-order longitudinal vibration of the integral structure; CN205453548U discloses a vibrator of a longitudinal-longitudinal combined linear ultrasonic motor, which is formed by combining two Lanjiwen vibrators into a stator in a positive-crossed manner, and utilizes two paths of longitudinal vibration to synthesize elliptical vibration at a stator driving head, wherein the vibrator is complex in pre-tightening and fixing and difficult to miniaturize; CN103401470A discloses a stator which utilizes two independent longitudinal vibration vibrators to form a V-shaped structure and realizes linear motion, and the stator also has the problems of pre-tightening and fixing and is difficult to miniaturize; CN1652447A discloses a thin plate type longitudinal bending combined vibrator, which utilizes the combination of bending vibration and longitudinal vibration of the whole vibrator to make the driving foot of the vibrator form elliptical vibration, and the vibrator with such a structure can not be made very short in order to make the 2 nd order bending vibration and 1 st order longitudinal vibration degenerate.

In addition, CN104467524A discloses an in-plane bending and longitudinal combination vibrator, which is a plate-type structure, and in order to make the overall in-plane bending vibration mode degenerate with the overall longitudinal vibration, the vibrator needs to have a certain width, and this vibrator can only set the driving head at the bending vibration node, and has a limited vibration amplitude and an undesirable effect.

Besides, CN102118118A discloses a bending-bending vibration combined oscillator, which uses two bending modes with different orders to form an oblique arc motion at the teeth of the stator, so as to implement reciprocating driving, and power signals with different frequencies need to be provided.

The ultrasonic motor is suitable for miniaturization, but the stator (vibrator) of the linear ultrasonic motor has some difficulties in miniaturization, which mainly shows that: firstly, the vibrator structure is not easy to realize miniaturization, and when the integral bending vibration and longitudinal vibration are combined, the length or the width direction is limited; secondly, the oscillator is fixed with certain difficulty, and the node of first-order longitudinal vibration and second-order bending vibration is selected at the general fixed position, but the bending vibration node has bending deformation, so that the bending vibration is weakened; thirdly, the pre-tightening mechanism is complex, the vibrators are usually driven by a single driving head, and a special pre-tightening mechanism is needed.

Disclosure of Invention

The invention provides a linear ultrasonic motor stator for overcoming the defects of the prior art. The stator is of a thin plate structure, has a degenerate result of combination of local second-order bending vibration of the driving legs and integral first-order longitudinal vibration of the stator, and has the advantages of large driving force, high driving speed, small volume, light weight and convenience in miniaturization by adopting double-driving-foot driving.

The invention relates to a linear ultrasonic motor stator, which comprises a stator elastic body and a piezoelectric ceramic piece; an open slot is cut on the stator elastic body along the length direction, and the stator elastic body is divided into a driving body and two symmetrical driving legs by the open slot;

two opposite outer side surfaces of the two driving legs are adhered with piezoelectric ceramic plates in axial symmetry and used for exciting local second-order bending vibration modes of the driving legs; the piezoelectric ceramic plates are attached to the side face, on the same face as the piezoelectric ceramic plates of the driving legs, of the driving body and used for exciting a first-order longitudinal vibration mode of the stator, the two piezoelectric ceramic plates are arranged in an axial symmetry mode, the upper ends of the two driving legs respectively extend to form driving feet, and the two driving feet are arranged in an axial symmetry mode; all the piezoelectric ceramic pieces are electrically connected with electrode plates.

It would be advantageous if the stator could be caused to produce both overall longitudinal vibration and localized bending vibration, for this purpose:

the invention provides an electric excitation method of a linear ultrasonic motor stator, which is characterized in that piezoelectric ceramics and combined excitation are adopted to enable the stator to generate integral longitudinal vibration and local bending vibration, and elliptical vibration is synthesized at the driving foot end part of the stator; the method comprises the following steps:

1) respectively sticking the negative electrode surfaces of the four piezoelectric ceramic plates polarized in the thickness direction to the side surfaces of the driving body and the driving leg of the stator elastic body, and coating electrode layers on the corresponding piezoelectric ceramic plates;

2) two optional points on two electrode layers on the driving leg are respectively used as electrode points and connected together to form an electrified electrode, two optional points on two electrode layers on the driving body are respectively used as electrode points and connected together to form an electrified electrode, and the stator elastomer is used as a ground electrode;

3) two paths of same-frequency sinusoidal voltage signals with the phase difference of pi/2 are used for simultaneously exciting local second-order bending vibration of the driving legs and integral first-order longitudinal vibration of the stator, so that two driving feet on the stator synthesize elliptical motions with the phase difference of pi/2 in time and opposite rotation directions, and the motion of the driving rotor in one direction is realized;

4) two paths of same-frequency sinusoidal voltage signals with negative pi/2 phase difference are used for simultaneously exciting local second-order bending vibration of the driving legs and integral first-order longitudinal vibration of the stator, so that two driving feet on the stator synthesize elliptical motion with negative pi/2 phase difference in time and opposite rotation directions, and the motion of the driving rotor in the direction opposite to the step 3) is realized.

In order to increase the energy input density of the stator, the driving power of the stator is increased, and therefore:

the invention also provides another linear ultrasonic motor stator, wherein a body of the stator is made of piezoelectric ceramic materials, an open slot is cut in the length direction of the body, and the body is divided into a driving body and two symmetrical driving legs by the open slot; the upper ends of the two driving legs are respectively provided with driving feet extending outwards, the two driving feet are arranged in an axial symmetry mode, two opposite outer side faces of the driving body are coated with electrode layers, and two opposite outer side faces of the two driving legs are coated with the electrode layers.

The linear ultrasonic motor stator based on the piezoelectric ceramic material also provides two electric excitation methods:

a method for electrically exciting a stator of a piezoelectric ceramic linear ultrasonic motor polarized in the thickness direction, comprising:

1) the polarization of the piezoelectric ceramic stator in the thickness direction divides each wide side of the whole piezoelectric ceramic stator in the length direction into three regions: drive leg region, drive body region and fixed area, on one broad side: coating an electrode layer on the driving body area, setting an electrode point as a conducting electrode, coating an electrode layer 3 on the driving leg area, respectively setting two electrode points, and communicating the two electrode points to serve as the other conducting electrode; on the other wide side, coating an electrode layer 3 on the driving body region, coating an electrode layer 3 on the driving leg region, and connecting the two regions as a common ground electrode;

2) two paths of same-frequency sinusoidal voltage signals with the phase difference of pi/2 are used for simultaneously exciting the local second-order bending vibration of the driving legs 1-4 and the integral first-order longitudinal vibration of the stator, so that two driving feet 1-41 on the stator synthesize elliptical motions with the phase difference of pi/2 in time and opposite rotation directions, and the motion of the driving rotor in one direction is realized;

3) two paths of same-frequency sinusoidal voltage signals with negative pi/2 phase difference are used for simultaneously exciting local second-order bending vibration of the driving legs 1-4 and integral first-order longitudinal vibration of the stator, so that two driving feet 1-41 on the stator synthesize elliptical motion with negative pi/2 phase difference in time and opposite rotation directions, and the motion of the driving rotor in the direction opposite to the step 2) is realized.

A method for electrically exciting a stator of a piezoelectric ceramic linear ultrasonic motor with polarization in the width direction, comprising:

1) the polarization of the piezoceramic stator in the width direction divides each thick side surface of the whole piezoceramic stator in the length direction into three regions: the driving leg area, the driving body area and the fixing area, wherein an electrode layer 3 is coated on the two driving body areas, electrode points of the driving body areas are arranged, one electrode point is used as a conducting electrode, and the other electrode point is used as a public ground electrode; coating an electrode layer 3 on the two driving leg areas, and arranging electrode points of the driving leg areas, wherein the electrode points are connected with a 180-degree inverter by a line and then communicated with the other electrode point to be used as the other electrified electrode;

Compared with the prior art, the invention has the beneficial effects that:

the stator is in an axisymmetric structure with an open slot in the middle, and is divided into a driving body and a driving leg, and the driving foot is enabled to do elliptic vibration by combining and degenerating local second-order bending vibration of the two driving legs of the stator and first-order longitudinal vibration of the stator, which is different from the principle that the general vibrator synthesizes an ellipse by adopting integral bending vibration and integral longitudinal vibration. The stator structure is simple in structure and convenient to process, can reduce the length, thickness and width of the stator, and is easy to miniaturize.

Due to the structural symmetry, the stator acoustic node (a point which does not vibrate, and a point which does not have displacement or corner) is definite, and the stator acoustic node can be fixed at the acoustic node, so that the effect of longitudinal and bending vibration modes is not influenced, and the stator acoustic node can be fixed reliably. The stator can also be directly fixed with the outside.

The stator is designed in an axisymmetric double-driving-foot structure, and the double driving feet generate a same-direction driving effect under combined excitation, so that the driving force is larger, and when the stator is used, the two driving feet of the stator can be clamped by the two side surfaces of the rotor, thereby realizing pre-tightening, so that the pre-tightening is simple and a special pre-tightening mechanism is not required to be designed.

Fourthly, when the stator is made of the integral piezoelectric ceramic (including but not limited to PZT4 or PZT8) materials, the bonding process of pasting the piezoelectric ceramic piece on the metal elastic body is omitted, the energy input density of the vibrator can be increased, the integral piezoelectric ceramic stator stores more deformation energy, and the driving power of the stator is improved.

The technical scheme of the invention is further explained by combining the drawings and the embodiment:

drawings

Fig. 1 is a schematic structural view of a stator of embodiment 1;

FIG. 2 is a side view of FIG. 1;

FIG. 3 is a schematic structural view of a piezoelectric ceramic stator in which electrode layers are sprayed in the thickness direction in example 2;

FIG. 4 is a side view of FIG. 4;

FIG. 5 is a schematic structural view of a piezoelectric ceramic stator having electrode layers sprayed in the width direction according to example 2;

fig. 6 is a schematic structural view of a stator of embodiment 3;

FIG. 7 is a schematic structural view of a stator according to embodiment 4;

FIG. 8 is a schematic structural view of a stator of embodiment 5;

fig. 9 is a schematic structural view of a stator of embodiment 6;

fig. 10 is a schematic structural view of a stator of embodiment 7;

FIG. 11 is a front view of an embodiment of the present invention with the drive foot rectangular;

FIG. 12 is a schematic view of the driving foot in FIG. 11 linearly contacting, fitting and pre-tightening with a dovetail slot mover;

FIG. 13 is a schematic view of the driving foot in FIG. 11 linearly contacting, fitting and pre-tightening with a double dovetail groove mover;

FIG. 14 is a front view of a single drive foot in the form of a right trapezoid in cross-section in an embodiment of the invention;

FIG. 15 is a schematic view of the driving foot in FIG. 14 being in contact fit with a dovetail slot mover surface for pretension;

FIG. 16 is a front view of a square frustum and rectangular parallelepiped combination of a single drive foot according to an embodiment of the invention;

FIG. 17 is a schematic view of the driving foot in FIG. 16 in contact fit with the double dovetail groove mover surface for pretension;

fig. 18 is a schematic view of an electric excitation configuration of a motor stator fabricated by compounding a stator elastic body and a piezoelectric ceramic sheet;

FIG. 19 is a diagram of the motion mechanism of the combined electrically stimulated composite drive foot of FIG. 18;

FIG. 20 is a schematic view of a thickness-wise polarized post-electrical excitation configuration of a piezoceramic material stator;

FIG. 21 is a diagram of the motion mechanism of the combined electrically stimulated synthetic drive foot of FIG. 20;

FIG. 22 is a schematic view of a width-wise polarized electro-active configuration of a piezoceramic material stator;

FIG. 23 is a diagram of the motion mechanism of the combined electrically stimulated synthetic drive foot of FIG. 22;

FIG. 24 is an overall first-order longitudinal vibration mode diagram of the stator of example 3;

fig. 25 is a partial second order bending mode diagram of the drive leg of example 3.

Detailed Description

Referring to fig. 1 to 2, a stator of a linear ultrasonic motor according to the present embodiment includes a stator elastic body 1 and a piezoelectric ceramic plate 2; the stator elastic body 1 is a metal elastic body, an open slot 1-1 is cut on the stator elastic body 1 along the length direction, and the stator elastic body 1 is divided into a driving body 1-3 and two symmetrical driving legs 1-4 by the open slot 1-1;

two opposite outer side surfaces of the two driving legs 1-4 are pasted with piezoelectric ceramic plates 2 which are in axial symmetry and used for exciting local second-order bending vibration modes of the driving legs 1-4;

the piezoelectric ceramic pieces 2 are attached to the side faces, located on the same face of the driving bodies 1-3 and the piezoelectric ceramic pieces of the driving bodies 1-4, and used for exciting a first-order longitudinal vibration mode of the whole stator, the two piezoelectric ceramic pieces 2 are arranged in an axial symmetry mode, the upper ends of the two driving legs 1-4 are respectively provided with driving feet 1-41 extending outwards, and the two driving feet 1-41 are arranged in an axial symmetry mode; all the piezoelectric ceramic plates 2 are coated with electrode layers 3.

The integral first-order longitudinal vibration mode of the stator and the local second-order bending vibration mode of the driving legs are degenerated, by means of combined excitation of two groups of piezoelectric ceramic plates for exciting bending vibration and longitudinal vibration, elliptical vibration is generated at the end parts of the driving feet of the stator, elliptical vibration in opposite rotating directions is synthesized at the end parts of the two driving feet, and the superposition effect of the two driving feet in the same direction is achieved. In addition, the double-driving foot of the stator of the embodiment is in an axisymmetric structure, when the stator is used, the elastic deformation of the thin-plate dovetail groove rotor is adopted to apply pretightening force to the contact surface of the stator and the rotor, and no independent pretightening force applying mechanism is provided.

As shown in fig. 3-5, another linear ultrasonic motor stator has a body made of piezoelectric ceramic material, an open slot 1-1 is cut along the length direction of the body, and the body is divided into a driving body 1-3 and two symmetrical driving legs 1-4 by the open slot 1-1; the upper ends of the two driving legs 1-4 are respectively provided with driving feet 1-41 which extend outwards, the two driving feet 1-41 are arranged in an axial symmetry mode, two opposite outer side faces of the driving bodies 1-3 are coated with electrode layers, and two opposite outer side faces of the two driving legs 1-4 are coated with the electrode layers.

When the stator is made of the integral piezoelectric ceramic (including but not limited to PZT4 or PZT8) material, the bonding process of pasting the piezoelectric ceramic piece on the metal elastic body is omitted, the energy input density of the vibrator can be increased, the integral piezoelectric ceramic vibrator stores more deformation energy, and the driving power of the vibrator is improved.

Based on the above technical solution, the following is further illustrated in the form of an embodiment:

example 1, as shown in fig. 1, this example further defines: the section of the open slot 1-1 is rectangular. The stator is processed into a regular rectangular groove, the bottom of the stator is straight, the stator is simple and convenient to manufacture, the size of the stator is guaranteed, the stator is easy to miniaturize, due to the symmetry of the structure, an acoustic node (a point without vibration, displacement and corner) of the stator is definite, and a mounting hole D can be formed in the acoustic node and used for fixing the stator, so that the effects of longitudinal vibration mode and bending vibration mode are not influenced, and the stator can be fixed and reliable.

Optionally, the width W of the open slot 1-1 is 0.2-10 mm, and the depth H is 0.5-10 mm.

Alternatively, the stator is mainly composed of a rectangular thin plate stator elastomer 1 and a piezoelectric ceramic plate 2, the piezoelectric ceramic plate is a rectangular thin plate structure, the rectangular driving feet 3 extending from the stator elastomer 1 are both constructed into a T-shaped structure, the length × width × thickness of the transverse side of the T-shaped structure is 5.0mm ×.5mm ×.5mm, the length × 2 width × thickness of the vertical side of the T-shaped structure is 9.5mm ×.0mm ×.5mm, as shown in fig. 1 and fig. 2, the T-shaped thin plate stator elastomer 1 has two driving feet 3 with axial symmetry, the middle is just 1-1 with certain width and depth, in this alternative embodiment, W is 1.8mm, the depth H is 3.7mm, the open slot 1-1 divides the stator elastomer 1 into three parts of a driving body 1-3 and two driving legs 1-4, as shown in fig. 1, the stator has a first-order longitudinal bending mode and a driving leg, the local longitudinal bending mode is a first-order longitudinal bending mode, the piezoelectric ceramic plate 1-3 is mounted on the lateral surface of the piezoelectric ceramic plate, the piezoelectric ceramic plate has a first-2 longitudinal mode mounting point, the piezoelectric ceramic plate has a second-2 mounting width, the piezoelectric ceramic plate mounting holes with a second-2 longitudinal mode mounting width, the piezoelectric ceramic plate mounting holes are a second-2 longitudinal mode mounting point mounting points, the piezoelectric ceramic plate mounting points of the.

Embodiment 2, as shown in fig. 3 and 4, the body of the piezoceramic material stator in this embodiment is a cuboid, and it is further defined that the electrode layers 3 are sprayed on two wide side surfaces in the length direction of the whole piezoceramic material stator, so as to facilitate excitation of the piezoceramic material stator polarized in the thickness direction. As shown in fig. 5, the present embodiment further defines that the electrode layers 3 are coated on two thick sides of the whole length direction of the piezoceramic material stator, so as to facilitate the excitation of the piezoceramic material stator polarized in the width direction.

Example 3, example 3 further limited in example 1 and/or example 2 by: the bottom corner of the open slot 1-1 is vertically provided with narrow slots 1-2 which are arranged in axial symmetry along the wall surface of the slot. The effect of the combination design of the open slot and the narrow slot on the adjustment of the degeneracy of the local second-order bending vibration modes of the two driving legs of the stator and the first-order longitudinal vibration mode of the whole stator is better. Fig. 6 shows the stator elastic body 1 having a narrow groove, and the whole body of the stator made of the piezoceramic material of example 2 has the same narrow groove as that of fig. 6, and is not shown.

The combination of the dimensions of the open slot 1-1 and the narrow slot 1-2, and the degenerated (same or close) frequencies of bending and longitudinal vibrations, is more effective in driving elliptical motion of the foot, optionally the narrow slot 1-2 has a width K of 0.1-1 mm and a depth L of 0.1-5 mm.

Alternatively, on the basis of an alternative to this embodiment 1 and/or embodiment 2, a width K of 0.3mm and a depth L of 0.5mm is chosen in this embodiment the dimensions of the open slot 1-1 and the narrow slot 1-2 form a good combination.

Embodiment 4, the open slot defined by this embodiment is: the section of the open slot 1-1 is V-shaped. The stator is made into a V-shaped open slot, the manufacture is simple and convenient, the miniaturization is easy, due to the symmetry of the structure, an acoustic node (a non-vibration point, a point without displacement or a corner) of the stator is definite, and a mounting hole D can be formed at the acoustic node for fixing the stator, so that the effect of longitudinal and bending vibration modes is not influenced, and the stator can be fixed reliably. The V-shaped open slot also has the result of degenerating the frequency combination of the integral first-order longitudinal vibration mode of the stator and the local second-order bending vibration mode of the driving leg, and the driving foot 3 can vibrate in an elliptic mode. As shown in fig. 7, the V-shaped grooves of the present embodiment are exemplified by the stator of the stator elastic body 1, and the V-shaped grooves of the entire piezoceramic material stator are the same as those of fig. 7, and are not shown.

Embodiment 5, the open slot defined by this embodiment is: the section of the open slot 1-1 is isosceles trapezoid. The open slot 1-1 is made into an isosceles trapezoid with a small upper part and a large lower part, is simple and convenient to manufacture and easy to miniaturize, and due to the symmetry of the structure, an acoustic node (a point without vibration, displacement or corner) of the stator is definite, and a mounting hole D can be formed at the acoustic node and used for fixing the stator, so that the effects of longitudinal and bending vibration modes are not influenced, and the stator can be fixed and reliable. The open slot of the isosceles trapezoid also has the result of degenerating the frequency combination of the integral first-order longitudinal vibration mode of the stator and the local second-order bending vibration mode of the driving leg, so that the driving foot 3 can vibrate elliptically. As shown in fig. 8, the isosceles trapezoid opening groove of the present embodiment is an example of the stator elastic body 1, and the isosceles trapezoid opening groove of the whole piezoceramic material stator is the same as that in fig. 8, and is omitted and not shown.

Embodiment 6, the open slot defined by this embodiment is: the section of the open slot 1-1 is a combination of a rectangle and a double dovetail groove. The open slot 1-1 is made into a combined shape with a rectangular upper part and a double dovetail groove lower part, is simple and convenient to manufacture and easy to miniaturize, and due to the structural symmetry, an acoustic node (a point without vibration, displacement and corner) of the stator is definite, and a mounting hole D can be formed at the acoustic node for fixing the stator, so that the effect of longitudinal and bending vibration modes is not influenced, and the stator can be fixed reliably. The combined-shape open slot also has the result of degenerating the frequency combination of the integral first-order longitudinal vibration mode of the stator and the local second-order bending vibration mode of the driving leg, and the driving foot 3 can vibrate in an elliptic mode. As shown in fig. 9, the opening groove 1-1 of the cross section of the present embodiment is an example of a stator of the stator elastic body 1, and the combined opening groove of the whole piezoceramic material stator is the same as that of fig. 9, and is not shown.

Embodiment 7, the open slot defined by this embodiment is: the section of the open slot 1-1 is a combination of double isosceles trapezoids. The open slot 1-1 is made into a double isosceles trapezoid combined shape with two large ends and a small middle, is simple and convenient to manufacture and easy to miniaturize, and due to the symmetry of the structure, an acoustic node (a non-vibration point, a point without displacement or a corner) of the stator is definite, and a mounting hole D can be formed at the acoustic node for fixing the stator, so that the effect of longitudinal and bending vibration modes is not influenced, and the stator can be fixed and reliable. The combined-shape open slot also has the result of degenerating the frequency combination of the integral first-order longitudinal vibration mode of the stator and the local second-order bending vibration mode of the driving leg, and the driving foot 3 can vibrate in an elliptic mode. As shown in fig. 10, the opening groove 1-1 of the cross section of the present embodiment is an example of a stator of the stator elastic body 1, and the combined opening groove of the whole piezoceramic material stator is the same as that in fig. 10, and is not shown.

Example 8, in the aspect of any of examples 1 to 7, each of the driving feet 3 has a rectangular parallelepiped shape. As shown in fig. 11-13, a stator composed of a stator elastic body 1 and a piezoelectric ceramic plate 2 is taken as an example for explanation, and fig. 12 shows that two corresponding edges on the upper surface of two driving feet 3 of the stator are respectively in line contact with the side surface of the inner wall of a dovetail groove mover (such as a thin plate structure). The mover with the structure needs to be guided and supported, but a separate pre-tightening mechanism is not needed to apply pre-tightening force to the contact surfaces of the stator and the mover, and alternatively, a 301 stainless steel thin plate with the thickness of 0.5mm can be selected as the thin-plate dovetail slot mover. Fig. 13 shows that four corresponding edges on the upper surfaces of two driving legs 3 of the stator are in line contact with the inner wall side surfaces of the double dovetail groove mover (e.g., thin plate structure). This structure has not only a large driving force but also a self-centering function of the mover as compared with the above, and the mover does not need a guide support. The driving foot of the whole piezoceramic material stator is the same as that in fig. 11-13, and is omitted.

Example 9 in the solution of any of examples 1 to 7, each of the driving feet 3 is a hexahedron having a right-angled trapezoid cross section. As shown in fig. 14-15, a stator composed of a stator elastic body 1 and a piezoelectric ceramic plate 2 is taken as an example for explanation, two driving feet 3 of the stator form a single-cone structure, and the side surface can be in two-position surface contact with the side surface of the inner wall of the thin-plate single-dovetail-groove mover. The sizes of the cone angles of the two driving feet 3 are the same as the included angles of the two deformed side surfaces of the dovetail groove-shaped rotor, the driving feet 3 with the structure can be in surface contact with the side surface of the inner wall of the dovetail groove-shaped rotor, the contact stress of the contact surface of the stator and the rotor is reduced, and the abrasion resistance of the contact surface of the stator and the rotor is improved. The driving foot of the whole piezoceramic material stator is the same as that in fig. 11-13, and is omitted.

Example 10, in the solution of any of examples 1 to 7, each of the driving feet 3 is a hexahedron having a right trapezoid cross section. Each driving foot 3 is a combination of a quadrangular frustum pyramid and a rectangular parallelepiped. As shown in fig. 16-17, taking a stator composed of a stator elastic body 1 and a piezoelectric ceramic plate 2 as an example, the heads of the two driving feet are constructed into a double-sided cone structure (a waist drum structure), and the side surface of the quadrangular frustum can be in four-surface contact with the side surface of the inner wall of the thin-plate type double-dovetail groove mover. The size of the corresponding taper angle of the quadrangular frustum pyramid is matched with the included angle of two side surfaces of the dovetail groove-shaped rotor after deformation, and the stator driving head part (the side surface of the quadrangular frustum pyramid) of the biconical structure can realize surface contact with the four side surfaces of the inner wall of the double dovetail groove-shaped rotor, so that the contact stress of the contact surface of the stator and the rotor is reduced, and the abrasion resistance of the contact surface of the stator and the rotor is further improved. Besides, the stator with the double-cone structure is in surface contact with the inner wall of the double-dovetail groove-shaped mover at four positions, so that a large driving force can be generated. The driving foot of the whole piezoceramic material stator is the same as that in fig. 16-17, and is omitted.

Based on the above-described embodiments and the stator structure of examples 1 to 10. It would be advantageous if the stator could be caused to produce both overall longitudinal vibration and localized bending vibration, and, for this purpose,

the present embodiment provides a method for electrically exciting a stator of a linear ultrasonic motor, as shown in fig. 18, which includes exciting the stator with an open slot and a narrow slot, the method including:

1) respectively sticking the negative electrode surfaces of four piezoelectric ceramic pieces 2 polarized in the thickness direction to the side surfaces of the driving bodies 1-3 and the driving legs 1-4 of the stator elastic body 1, and simultaneously coating the electrode layers 3 on the corresponding piezoelectric ceramic pieces 2;

2) two optional points on the two electrode layers 3 on the driving legs 1-4 are respectively used as electrode points and connected together to form an electrified electrode, two optional points on the two electrode layers 3 on the driving bodies 1-3 are respectively used as electrode points and connected together to form an electrified electrode, and the stator elastomer is used as a common ground electrode;

3) two paths of same-frequency sinusoidal voltage signals with the phase difference of pi/2 are used for simultaneously exciting the local second-order bending vibration of the driving legs 1-4 and the first-order longitudinal vibration of the stator, so that two driving feet 1-41 on the stator synthesize elliptical motions with the phase difference of pi/2 in time and opposite rotation directions, and the motion of the driving rotor in one direction is realized;

4) two paths of same-frequency sinusoidal voltage signals with negative pi/2 phase difference are used for simultaneously exciting local second-order bending vibration of the driving legs 1-4 and first-order longitudinal vibration of the stator, so that two driving feet 1-41 on the stator synthesize elliptical motion with negative pi/2 phase difference in time and opposite rotation directions, and the motion of the driving rotor in the direction opposite to the step 3) is realized.

As an example: as shown in fig. 18 and 19, fig. 24 and fig. 25, first, the negative electrode faces of 4 piezoelectric ceramic sheets 2 polarized in the thickness direction are respectively adhered to the two side faces of the driving legs 1 to 4 and the driving bodies 1 to 3 of the stator elastic body 1, while the electrode layers 3 are coated on the corresponding piezoelectric ceramic sheets 2, then, optionally two electrode points M and N on the surface of the electrode layer 3 on the driving legs 1 to 4 are connected to make one conducting electrode, optionally two electrode points P and Q on the surface of the electrode layer 3 on the driving bodies 1 to 3 are connected to make another conducting electrode, and the stator elastic body 1 is used as a common ground electrode; secondly, the two paths of same-frequency sinusoidal voltage signals V1 and V2 with the phase difference of pi/2 are used for simultaneously exciting the bent piezoelectric ceramic piece and the longitudinal-vibration piezoelectric ceramic piece, so that the integral first-order longitudinal vibration of the stator and the local second-order bending vibration of the driving legs 1 to 4 can be excited, the local second-order bending vibration of the two driving legs 1 to 4 is completely axisymmetric vibration, the whole driving body 1 to 3 is used as a fixed end of the bending vibration, and the degeneracy of the modal frequency of the local second-order bending vibration of the two driving legs and the integral first-order longitudinal vibration of the stator can be realized by adjusting the width and the depth of the open slot 1 to 1 and the small narrow slot 1 to 2, as shown in fig. 19, in the embodiment, the driving frequency of the modal degeneracy is 245 kHz. Finally, since the phase difference between the first-order longitudinal vibration of the entire stator and the second-order bending vibration of the local drive legs is pi/2, elliptical vibrations with opposite rotation directions can be synthesized at the ends of the two drive legs 1 to 41 of the stator, respectively, as shown in fig. 19, so that the stator has a function of driving the mover to move in one direction. If the phase difference of two paths of same-frequency sinusoidal voltage signals is exchanged, the elliptical vibration at the end part of each driving head can be reversed, so that the stator has the function of driving the rotor to move in the opposite direction.

Another embodiment provides a method of electrical excitation of a linear ultrasonic motor stator, as shown in fig. 20, with an entire piezoceramic stator excitation with open slots and narrow slots, the method comprising:

1) the polarization of the piezoelectric ceramic stator in the thickness direction divides each wide side of the whole piezoelectric ceramic stator in the length direction into three regions: drive leg region E, drive body region T and fixed area S, on one broad side: coating an electrode layer 3 on the driving body area T, setting an electrode point U1 as a conducting electrode, coating the electrode layer 3 on the driving leg area E, respectively setting two electrode points W1 and W2, and connecting the two electrode points to serve as the other conducting electrode; on the other wide side, coating the electrode layer 3 on the driving body region T, coating the electrode layer 3 on the driving leg region E, and connecting the two regions as a common ground electrode;

3) two paths of same-frequency sinusoidal voltage signals V1 and V2 with negative pi/2 phase difference are used for simultaneously exciting local second-order bending vibration of the driving legs 1-4 and integral first-order longitudinal vibration of the stator, so that two driving feet 1-41 on the stator synthesize elliptical motion with negative pi/2 phase difference in time and opposite rotation directions, and the motion of the driving rotor in the direction opposite to the step 2) is realized. As shown in fig. 21, in the present embodiment, the driving frequency of modal degeneracy is 245 kHz. Finally, because the phase difference between the first-order longitudinal vibration of the whole stator and the second-order bending vibration of the local drive legs 1-4 is pi/2, elliptical vibrations with opposite rotation directions can be synthesized at the end parts of the two drive feet 1-41 of the stator respectively, as shown in fig. 21, so that the stator has the function of driving the rotor to move in one direction. If the phase difference of two paths of same-frequency sinusoidal voltage signals is exchanged, the elliptical vibration at the end part of each driving head can be reversed, so that the stator has the function of driving the rotor to move in the opposite direction.

Another embodiment also provides a method of electrical excitation of a linear ultrasonic motor stator, as shown in fig. 22, of a whole piezoceramic stator with open slots and narrow slots, the method comprising:

1) the polarization of the piezoceramic stator in the width direction divides each thick side surface of the overall piezoceramic stator in the length direction into three regions: the driving leg region R, the driving body region K and the fixing region S, an electrode layer 3 is coated on the two driving body regions R, electrode points Q1 and Q2 are arranged, one electrode point (such as an electrode point Q1) is used as a conducting electrode, the other electrode point (such as an electrode point Q2) is used as a common ground electrode, the electrode layer 3 is coated on the two driving leg regions R, electrode points M1 and N1 are arranged, the electrode point M1 is connected with a 180-degree inverter through a line, and the electrode point M1 is communicated with the other electrode point N1 to be used as the other conducting electrode;

2) two paths of same-frequency sinusoidal voltage signals V1 and V2 with the phase difference of pi/2 are used for simultaneously exciting the local second-order bending vibration of the driving legs 1-4 and the integral first-order longitudinal vibration of the stator, so that two driving feet 1-41 on the stator synthesize elliptical motions with the phase difference of pi/2 in time and opposite rotation directions, and the motion of the driving rotor in one direction is realized;

3) two paths of same-frequency sinusoidal voltage signals with negative pi/2 phase difference are used for simultaneously exciting local second-order bending vibration of the driving legs 1-4 and integral first-order longitudinal vibration of the stator, so that two driving feet 1-41 on the stator synthesize elliptical motion with negative pi/2 phase difference in time and opposite rotation directions, and the motion of the driving rotor in the direction opposite to the step 2) is realized. As shown in fig. 23, in the present embodiment, the driving frequency of modal degeneracy is 245 kHz. Finally, because the phase difference between the first-order longitudinal vibration of the whole stator and the second-order bending vibration of the local drive legs 1-4 is pi/2, elliptical vibrations with opposite rotation directions can be synthesized at the end parts of the two drive feet 1-41 of the stator respectively, as shown in fig. 23, so that the stator has the function of driving the rotor to move in one direction. If the phase difference of two paths of same-frequency sinusoidal voltage signals is exchanged, the elliptical vibration at the end part of each driving head can be reversed, so that the stator has the function of driving the rotor to move in the opposite direction.

The present invention is not limited to the above embodiments, and those skilled in the art can make various changes and modifications without departing from the scope of the invention.

Claims

1. A linear ultrasonic motor stator comprises a stator elastic body (1) and a piezoelectric ceramic piece (2); the method is characterized in that: the stator elastic body (1) is a metal elastic body, an open slot (1-1) is cut on the stator elastic body (1) along the length direction, and the stator elastic body (1) is divided into a driving body (1-3) and two symmetrical driving legs (1-4) by the open slot (1-1);

two opposite outer side surfaces of the two driving legs (1-4) are pasted with piezoelectric ceramic plates (2) which are axisymmetric and used for exciting local second-order bending vibration modes of the driving legs (1-4);

the piezoelectric ceramic plates (2) are attached to the side faces, located on the same face with the piezoelectric ceramic plates of the driving legs (1-4), of the driving bodies (1-3) and used for exciting a first-order longitudinal vibration mode of the whole stator, the two piezoelectric ceramic plates (2) are arranged in an axial symmetry mode, the upper ends of the two driving legs (1-4) are respectively provided with driving feet (1-41) extending outwards, and the two driving feet (1-41) are arranged in an axial symmetry mode; all the piezoelectric ceramic plates (2) are coated with electrode layers (3).

2. A linear ultrasonic motor stator is characterized in that: the stator is characterized in that a body of the stator is made of piezoelectric ceramic materials, an open slot (1-1) is cut in the body along the length direction, and the body is divided into a driving body (1-3) and two symmetrical driving legs (1-4) by the open slot (1-1); the upper ends of the two driving legs (1-4) are respectively provided with driving feet (1-41) extending outwards, the two driving feet (1-41) are arranged in an axial symmetry manner, two opposite outer side surfaces on the driving bodies (1-3) are coated with electrode layers (3), and two opposite outer side surfaces on the two driving legs (1-4) are coated with the electrode layers (3).

3. The linear ultrasonic motor stator according to claim 1 or 2, characterized in that: the section of the open slot (1-1) is rectangular.

4. The linear ultrasonic motor stator of claim 3, wherein: the width (W) of the open slot (1-1) is 0.2-10 mm, and the depth (H) is 0.5-10 mm.

5. The linear ultrasonic motor stator of claim 4, wherein: narrow grooves (1-2) which are axially symmetrically arranged are vertically arranged at the corners of the bottoms of the open grooves (1-1) along the wall surfaces of the grooves.

6. The linear ultrasonic motor stator according to claim 5, wherein the narrow slots (1-2) have a width (K) of 0.1-1 mm and a depth (L) of 0.1-5 mm.

7. The linear ultrasonic motor stator according to claim 3, characterized in that: the section of the open slot (1-1) is a combination of a V shape, an isosceles trapezoid, a rectangle and a double dovetail groove, or a combination of double isosceles trapezoids.

8. The linear ultrasonic motor stator of claim 3, wherein: each driving foot (1-41) is a cuboid.

9. The linear ultrasonic motor stator of claim 3, wherein: each driving foot (1-41) is a hexahedron with a right-angled trapezoid cross section.

10. The linear ultrasonic motor stator of claim 3, wherein: each driving foot (1-41) is a combination of a quadrangular frustum pyramid and a cuboid.

11. The method of claim 1, wherein the step of electrically exciting the stator of the linear ultrasonic motor comprises: the method comprises the following steps:

1) respectively sticking the negative electrode surfaces of four piezoelectric ceramic pieces (2) polarized in the thickness direction to the side surfaces of a driving body (1-3) and a driving leg (1-4) of the stator elastic body (1), and coating an electrode layer on the corresponding piezoelectric ceramic piece (2);

2) two optional points on the two electrode layers (3) on the driving legs (1-4) are respectively used as electrode points and connected together to form a conducting electrode, two optional points on the two electrode layers (3) on the driving bodies (1-3) are respectively used as electrode points and connected together to form a conducting electrode, and the stator elastic body is used as a common ground electrode;

3) two paths of same-frequency sinusoidal voltage signals with the phase difference of pi/2 are used for simultaneously exciting the local second-order bending vibration of the driving legs (1-4) and the integral first-order longitudinal vibration of the stator, so that two driving feet (1-41) on the stator synthesize elliptical motions with the phase difference of pi/2 in time and opposite rotation directions, and the motion of the driving rotor in one direction is realized;

4) two paths of same-frequency sinusoidal voltage signals with negative pi/2 phase difference are used for simultaneously exciting local second-order bending vibration of the driving legs (1-4) and integral first-order longitudinal vibration of the stator, so that two driving feet (1-41) on the stator synthesize elliptical motions with negative pi/2 phase difference in time and opposite rotation directions, and the motion of the driving rotor in the direction opposite to the step 3) is realized.

12. The method of claim 2, wherein the step of electrically exciting the stator of the linear ultrasonic motor comprises: the method comprises the following steps:

1) the polarization of the piezoelectric ceramic stator in the thickness direction divides each wide side of the whole piezoelectric ceramic stator in the length direction into three regions: drive leg region, drive body region and fixed area, on one broad side: coating an electrode layer on the driving body area, setting an electrode point as a conducting electrode, coating an electrode layer (3) on the driving leg area, respectively setting two electrode points, and communicating the two electrode points to serve as the other conducting electrode; on the other wide side, an electrode layer (3) is coated on the driving body region, an electrode layer (3) is coated on the driving leg region, and the two regions are connected to be used as a common ground electrode;

2) two paths of same-frequency sinusoidal voltage signals with the phase difference of pi/2 are used for simultaneously exciting the local second-order bending vibration of the driving legs (1-4) and the integral first-order longitudinal vibration of the stator, so that two driving feet (1-41) on the stator synthesize elliptical motions with the phase difference of pi/2 in time and opposite rotation directions, and the motion of the driving rotor in one direction is realized;

3) two paths of same-frequency sinusoidal voltage signals with negative pi/2 phase difference are used for simultaneously exciting local second-order bending vibration of the driving legs (1-4) and integral first-order longitudinal vibration of the stator, so that two driving feet (1-41) on the stator synthesize elliptical motions with negative pi/2 phase difference in time and opposite rotation directions, and the motion of the driving rotor in the direction opposite to the step 2) is realized.

13. The method of claim 2, wherein the step of electrically exciting the stator of the linear ultrasonic motor comprises: the method comprises the following steps:

1) the polarization of the piezoceramic stator in the width direction divides each thick side surface of the whole piezoceramic stator in the length direction into three regions: the driving leg area, the driving body area and the fixing area are coated with electrode layers (3), electrode points of the driving body area are arranged, one electrode point is used as a conducting electrode, and the other electrode point is used as a public ground electrode; coating an electrode layer (3) on the two driving leg areas, and arranging electrode points of the driving leg areas, wherein the electrode points are connected with a 180-degree inverter by a line and then communicated with the other electrode point to serve as the other electrified electrode;