Embedded lever type double piezoelectric stack driving structure

Abstract

The invention relates to the technical field of intelligent material vibration control, in particular to an embedded lever type double piezoelectric stack driving structure which comprises a sleeve, outer piezoelectric stack structures and a lever amplification structure, a mounting plate is arranged in one end of the sleeve, and four parallel inner piezoelectric stack structures are evenly distributed on the mounting plate around the center of the mounting plate; the outer ring of the sleeve is sleeved with an annular outer piezoelectric stack structure. Wherein the four inner piezoelectric stack structures are connected in parallel and then are connected in series with the outer piezoelectric stack structure; and the lever amplification structure is used for amplifying the deformation of the inner piezoelectric stack structure. The mode of piezoelectric ceramic stacking, mechanical series connection and circuit parallel connection is adopted, when an electric field acts on the piezoelectric stack structure, piezoelectric ceramic of each layer can deform in the polarization direction, the piezoelectric stack is integrally lengthened, and the output quantity of the double-piezoelectric-stack driving structure meets the large-displacement application scene.

Description

Technical Field

[0001] The present invention relates to the technical field of intelligent material vibration control, and in particular to an embedded lever-type dual piezoelectric stack driving structure. Background Art

[0002] In actual engineering projects such as aircraft engine connection structures, vibration failures may cause serious problems and even lead to engine failure and catastrophic consequences, so effective vibration reduction and isolation measures must be taken to deal with them. As the core connection component between the casing and the accessories, the bracket plays the role of transferring loads and providing support. However, given the structural and dimensional limitations of the bracket itself, traditional vibration reduction methods are not suitable for this structure, and structural vibration control methods based on smart materials have emerged.

[0003] Ceramic materials are usually composed of microcrystals, each of which is composed of atoms with positive or negative charges. Ferroelectric ceramics undergo spontaneous polarization, generating balanced positive and negative charges on both surfaces, thus forming piezoelectric ceramic materials. Based on different driving conditions, the piezoelectric effect can be divided into positive piezoelectric effect and inverse piezoelectric effect. The piezoelectric material is polarized due to external force, and the amount of charge generated by the force is proportional to the magnitude of the external force. This effect is called positive piezoelectric effect; the phenomenon of mechanical deformation of piezoelectric materials by applying an alternating electric field is called inverse piezoelectric effect.

[0004] Based on the inverse piezoelectric effect of piezoelectric ceramic materials, a variable stiffness device of a dual piezoelectric stack is designed. By applying different forms of electric fields to the piezoelectric ceramic material, deformation or movement is generated. The displacement and control force output by a single piece of piezoelectric ceramic are limited, and often cannot achieve the control effect required by the structure.

[0005] Therefore, it is necessary to provide an embedded lever-type dual piezoelectric stack driving structure to solve the above problems. Summary of the invention

[0006] The invention provides an embedded lever-type dual piezoelectric stack driving structure to solve the existing problems.

[0007] An embedded lever-type dual piezoelectric stack driving structure of the present invention adopts the following technical solution, including: A sleeve, one end of which is provided with a mounting plate, and a plurality of parallel internal piezoelectric stack structures are evenly arranged on the mounting plate around the center of the mounting plate; An annular outer piezoelectric stack structure is mounted on the sleeve, one end of which is connected to the top of the sleeve, and the other end of which is connected to a base ring, wherein the length of the outer piezoelectric stack structure is greater than the sleeve; wherein a plurality of inner piezoelectric stack structures are connected in parallel and then in series with the outer piezoelectric stack structure; and a lever amplification structure for amplifying the deformation of the internal piezoelectric stack structure, comprising a plurality of vertical levers, each of which is hinged to a horizontal lever at the top, one end of the vertical lever being fixed to a mounting plate in the sleeve, the other end of the vertical lever being hinged to the end of the horizontal lever, and the ends of all the horizontal levers facing away from the vertical levers being connected to one point; The top of each internal piezoelectric stack structure is hinged to the bottom of a horizontal lever.

[0008] Preferably, the external piezoelectric stack structure includes: a plurality of stacked polarized piezoelectric rings, each polarized piezoelectric ring includes: two arc electrodes and an even number of arc-shaped piezoelectric ceramic sheets, the two arc electrodes and the even number of arc-shaped piezoelectric ceramic sheets are connected to form a polarized piezoelectric ring, wherein the two arc electrodes are separated by the arc-shaped piezoelectric ceramic sheets, the two arc electrodes of the same polarized piezoelectric ring are connected in parallel, and the arc electrodes between adjacent polarized piezoelectric rings are connected in series in sequence.

[0009] Preferably, the polarized piezoelectric ring comprises: two arc-shaped electrodes and four arc-shaped piezoelectric ceramic sheets, each two arc-shaped piezoelectric ceramic sheets are connected to form a piezoelectric ceramic segment, and the ends of the two piezoelectric ceramic segments are connected to the arc-shaped electrode.

[0010] Preferably, the internal piezoelectric stack structure includes: a plurality of stacked square piezoelectric ceramic sheets, with a square electrode between every two adjacent square piezoelectric ceramic sheets, wherein the square piezoelectric ceramic sheets and the square electrodes are connected in series, and the plurality of internal piezoelectric stack structures are connected in parallel, and the parallel internal piezoelectric stack structures are connected in series with the external piezoelectric stack structure.

[0011] Preferably, an insulating plate is provided on the top of the internal piezoelectric stack structure, the insulating plate and the bottom of the horizontal lever are hinged, and the common connection point of the horizontal lever is located on the central axis of the sleeve.

[0012] Preferably, a retaining ring is radially arranged at the top end of the sleeve, and the retaining ring is fixedly sleeved with the sleeve, wherein the top end of the outer piezoelectric stack structure is fixed to the retaining ring.

[0013] A design method for an embedded lever-type dual piezoelectric stack drive structure, comprising: The deformation of each internal piezoelectric stack structure is obtained according to the first-order piezoelectric equation and the amplification factor of the lever amplification structure, and the total deformation expression of all internal piezoelectric stack structures is obtained; According to the third kind of piezoelectric equation, the deformation expression of the external piezoelectric stack structure is obtained; According to the deformation expression of the outer piezoelectric stack structure and the deformation expression of all the inner piezoelectric stack structures output, the total displacement expression of the dual piezoelectric stack driving structure is constructed; According to the equivalent stiffness principle of series structure, the total expression of the equivalent stiffness of all internal piezoelectric stack structures and the expression of the equivalent stiffness of the external piezoelectric stack structure are obtained; According to the expressions of equivalent stiffness of all internal piezoelectric stack structures and the expressions of equivalent stiffness of external piezoelectric stack structures; constructing the total equivalent stiffness expression of the dual piezoelectric stack drive structure; According to the total displacement expression and the total equivalent stiffness expression, the relationship between the design parameters of the dual piezoelectric stack drive structure and the output force of the dual piezoelectric stack drive structure is constructed, wherein the design parameters are: the magnification of the lever amplification structure, the area of ​​the arc-shaped ceramic piece in a single polarized piezoelectric ring, the area of ​​a single square piezoelectric ceramic piece, and the number of internal piezoelectric stack structures; According to the relationship between the design parameters of the dual piezoelectric stack driving structure and the output force of the dual piezoelectric stack driving structure, as well as the required output force of the dual piezoelectric stack driving structure, the design parameters when designing the dual piezoelectric stack driving structure are obtained, and the dual piezoelectric stack driving structure is designed.

[0014] Preferably, the total displacement expression of the dual piezoelectric stack driving structure is:

[0015] In the formula, represents the total displacement of the dual piezoelectric stack driving structure; Indicates the total deformation of the internal piezoelectric stack structure; Indicates the deformation of the external piezoelectric stack structure; Indicates the magnification factor of the lever amplification structure on the deformation of the internal piezoelectric stack structure; Indicates the number of internal piezoelectric stack structures; represents the piezoelectric constant; Represents the area of ​​the square piezoelectric ceramic piece; Represents the area of ​​the arc-shaped ceramic piece within a single polarized piezoelectric ring; Indicates the number of square piezoelectric ceramic pieces in the internal piezoelectric stack structure; Represents the number of polarized piezoelectric rings in the internal piezoelectric stack structure; Indicates the applied voltage; It indicates the short-circuit elastic compliance coefficient of the square piezoelectric ceramic material when the electric field intensity E is constant; Indicates the pressure at both ends of the internal piezoelectric stack; Indicates the pressure at both ends of the external piezoelectric stack; Indicates the thickness of a single square piezoelectric ceramic piece; represents the thickness of a single polarized piezoelectric ring; It represents the elastic compliance coefficient of the annular piezoelectric ceramic material when the electric field strength is 0 or constant.

[0016] Preferably, the total equivalent stiffness expression of the dual piezoelectric stack driving structure is:

[0017]

[0018]

[0019] In the formula, represents the total equivalent stiffness of the dual piezoelectric stack drive structure; Represents the total equivalent stiffness of all internal piezoelectric stack structures; Represents the total equivalent stiffness of the internal piezoelectric stack structure; Represents the area of ​​the square piezoelectric ceramic piece; Represents the area of ​​the arc-shaped ceramic piece within a single polarized piezoelectric ring; represents the elastic modulus of the copper electrode; It indicates the open circuit elastic stiffness coefficient of the piezoelectric ceramic material when the electric field strength E is zero or constant; represents the number of layers of copper electrodes in the external piezoelectric stack; Indicates the number of layers of copper electrodes in the internal piezoelectric stack; Indicates the thickness of the piezoelectric ceramic stack within a single chip; Indicates the thickness of the single-piece external piezoelectric ceramic stack; Indicates the thickness of a single copper electrode; Indicates the number of external piezoelectric ceramic stacks; Indicates the number of piezoelectric ceramics in the stack.

[0020] Preferably, the relationship between the amplification factor of the lever amplification structure, the area of ​​the arc-shaped ceramic sheet in a single polarized piezoelectric ring, the area of ​​a single square piezoelectric ceramic sheet, the number of internal piezoelectric stack structures, and the output force of the dual piezoelectric stack drive structure is as follows:

[0021] In the formula, represents the output force of the dual piezoelectric stack driving structure; represents the total equivalent stiffness of the dual piezoelectric stack drive structure.

[0022] The beneficial effects of the present invention are: 1. By setting up multiple parallel internal piezoelectric stack structures, and connecting the parallel internal piezoelectric stack structures and the external piezoelectric stack structures in series, that is, the deformation of the top of the external piezoelectric stack structure drives the sleeve to move in the vertical direction, and the multiple parallel internal piezoelectric stack structures are placed in the sleeve and move upward accordingly, the superposition of deformation is achieved, and the total deformation is amplified by the lever amplification structure, thereby achieving the amplification of the output displacement of the dual piezoelectric stack drive structure. That is, the present invention adopts the method of piezoelectric ceramic stacking, mechanical series connection, and circuit parallel connection. When the electric field acts on the piezoelectric stack structure, each layer of piezoelectric ceramics will deform in the polarization direction, and the piezoelectric stack will grow as a whole, so that the output of the dual piezoelectric stack drive structure meets the application scenario of large displacement.

[0023] 2. Use piezoelectric smart materials to achieve structural vibration control; through structural design and improvement, the present invention solves the problem of limited output displacement and control force of monolithic piezoelectric ceramic materials, so that the engineering structure can achieve the required control effect. At the same time, the maximum output displacement and output force expressions of the structure are derived based on the piezoelectric effect equation, and the results are verified by COMSOL simulation software, which can provide corresponding model structures and maximum output theoretical guidance for practical engineering applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 A schematic diagram of an embedded lever-type dual piezoelectric stack driving structure of the present invention; Figure 2 An exploded view of an outer piezoelectric stack structure and a sleeve in an embedded lever-type dual piezoelectric stack driving structure of the present invention; Figure 3 It is a structural schematic diagram of a polarized piezoelectric ring of an outer piezoelectric stack structure in an embedded lever-type dual piezoelectric stack driving structure of the present invention; Figure 4 It is a schematic diagram of an internal piezoelectric stack structure in an embedded lever-type dual piezoelectric stack driving structure of the present invention; Figure 5 It is a schematic diagram of the connection between the lever amplification structure and the mounting plate in an embedded lever-type dual piezoelectric stack driving structure of the present invention; Figure 6 It is a force diagram of a lever amplification structure in an embedded lever-type dual piezoelectric stack driving structure of the present invention; Figure 7is a diagram showing the relationship between deformation and force arm in an embodiment of the present invention; Figure 8 Schematic diagram of electromechanical coupling of a single square piezoelectric ceramic sheet in an embodiment of the present invention; Fig. 9 A specific schematic diagram of the internal piezoelectric stack structure in an embodiment of the present invention; Fig.10 FIG. 4 is a COMSOL displacement simulation diagram of the embedded lever-type dual piezoelectric stack driving structure in an embodiment of the present invention.

[0026] In the figure: 1. base ring; 2. external piezoelectric stack structure; 3. sleeve; 4. lever amplification structure; 5. internal piezoelectric stack structure; 6. mounting plate; 7. insulating plate; 21. arc-shaped piezoelectric ceramic sheet; 22. arc-shaped electrode; 41. vertical lever; 42. horizontal lever. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] An embedded lever-type dual piezoelectric stack driving structure of the present invention is exemplarily described with reference to the accompanying drawings: For example, Figure 1 and Figure 2 As shown, an embedded lever-type dual piezoelectric stack driving structure of the present invention comprises: a sleeve 3, a mounting plate 6 and a lever amplification structure 4, wherein a mounting plate 6 is fixedly mounted inside one end of the sleeve 3, and four parallel internal piezoelectric stack structures 5 are evenly arranged on the mounting plate 6 around the center of the mounting plate 6; an annular external piezoelectric stack structure 2 is mounted on the sleeve 3, one end of the external piezoelectric stack structure 2 is connected to the top of the sleeve 3, and the other end of the external piezoelectric stack structure 2 is connected to a base ring 1, wherein the length of the external piezoelectric stack structure 2 is greater than that of the sleeve 3; wherein a plurality of internal piezoelectric stacks The structure 5 is connected in parallel and in series with the external piezoelectric stack structure 2; the lever amplification structure 4 is used to amplify the deformation of the internal piezoelectric stack structure 5, and the lever amplification structure 4 includes four vertical levers 41, each vertical lever 41 is hinged to a horizontal lever 42 at the top, one end of the vertical lever is fixed to the mounting plate 6 in the sleeve 3, the other end of the vertical lever 41 is hinged to the end of the horizontal lever 42, and all the ends of the horizontal levers 42 facing away from the vertical lever 41 are connected to one point; wherein, the top of each internal piezoelectric stack structure 5 is hinged to the bottom of a horizontal lever 42.

[0029] like Figure 5 , Figure 6 and Figure 7 As shown, it should be noted that Figure 6 As shown, the hinge point of the vertical lever 41 and the horizontal lever 42 forms the fulcrum of the lever structure, a power arm is formed between the fulcrum and the hinge point between the horizontal lever 42 and the top of the internal piezoelectric stack structure 5, and the resistance arm of the lever structure is formed from the fulcrum to the common connection point of all horizontal levers. The top of the internal piezoelectric stack structure 5 is the input end, and the common connection point of all horizontal levers is the output end. According to the lever principle, power × power arm = resistance × resistance arm. The magnification of the lever structure is related to the ratio of the length of the resistance arm to the power arm. The larger the ratio, the higher the magnification of the structural deformation. In this embodiment, Figure 6 and Figure 7 As shown in the figure, the power arm in the lever amplification structure is smaller than the resistance arm, so it is equivalent to a laborious lever; the laborious lever can save the distance of power movement. When the power movement is very small, another distance can be moved a lot, achieving the purpose of amplifying the deformation; the four horizontal levers are respectively connected to the four internal piezoelectric stack structures, and the common connection point of the horizontal levers is connected to the output rod. The output rod superimposes the deformation of the external piezoelectric stack and the amplified deformation of the internal piezoelectric stack and transmits them upward.

[0030] Exemplarily, the outer piezoelectric stack structure 2 includes: a plurality of stacked polarized piezoelectric rings, such as Figure 3 As shown, each polarized piezoelectric ring includes: two arc-shaped electrodes 22 and four arc-shaped piezoelectric ceramic sheets 21, each two arc-shaped piezoelectric ceramic sheets 21 are connected to form a piezoelectric ceramic segment, and the arc-shaped electrode 22 is connected between the ends of the two piezoelectric ceramic segments, that is, the two arc-shaped electrodes 22 and the four arc-shaped piezoelectric ceramic sheets 21 are connected to form a polarized piezoelectric ring, wherein the two arc-shaped electrodes 22 of the same polarized piezoelectric ring are connected in parallel, and the arc-shaped electrodes 22 between adjacent polarized piezoelectric rings are connected in series in sequence.

[0031] For example, Figure 4 As shown, the internal piezoelectric stack structure 5 includes: a plurality of stacked square piezoelectric ceramic sheets, with a square electrode between every two adjacent square piezoelectric ceramic sheets, wherein Fig. 9 As shown, the square piezoelectric ceramic sheets and the square electrodes are connected in series, a plurality of inner piezoelectric stack structures 5 are connected in parallel, and the parallel-connected inner piezoelectric stack structures 5 are connected in series with the outer piezoelectric stack structure 2 .

[0032] For example, Figure 4 and Figure 5 As shown, an insulating plate 7 is provided on the top of the internal piezoelectric stack structure 5, and the insulating plate 7 is hinged to the bottom of the horizontal lever 42, and as shown in FIG. Figure 1 As shown, the common connection point of the horizontal levers 42 is located on the central axis of the sleeve 3.

[0033] For example, Figure 1 and Figure 2As shown, a retaining ring is radially arranged at the top end of the sleeve 3, and the retaining ring is fixedly sleeved with the sleeve 3, wherein the top end of the outer piezoelectric stack structure 2 is fixed to the retaining ring.

[0034] In addition, this embodiment is only one embodiment of the present invention. Specifically, for the embedded lever-type dual piezoelectric stack driving structure of the present invention, the area, thickness and stacking number of piezoelectric ceramic sheets in the embedded lever-type dual piezoelectric stack driving structure can be adjusted as required. Different parameter changes correspond to different output quantities. The combination of different parameters can realize the multi-functional and multi-working condition application of the embedded lever-type dual piezoelectric stack structure. When the embedded lever-type dual piezoelectric stack driving structure requires a larger output displacement, it can be achieved by adjusting the lever amplification structure to increase the amplification factor or increase the driving voltage without changing the number of piezoelectric stack layers; when the embedded lever-type dual piezoelectric stack driving structure requires a larger equivalent stiffness, it can be achieved by increasing the area of ​​the piezoelectric sheet or reducing the number of piezoelectric stack layers and the thickness of the piezoelectric sheet; when the embedded lever-type dual piezoelectric stack driving structure requires a larger output force, it can be achieved by increasing the input voltage, increasing the amplification factor or increasing the number of stack layers.

[0035] A design method for an embedded lever-type dual piezoelectric stack drive structure, comprising: Step 1, constructing a total displacement expression of the dual piezoelectric stack driving structure; Exemplarily, in step 1, the steps of constructing the total displacement expression of the dual piezoelectric stack driving structure are as follows: step 11, obtaining the deformation of each inner piezoelectric stack structure according to the first kind of piezoelectric equation and the amplification factor of the lever amplification structure, and obtaining the total deformation expression of all inner piezoelectric stack structures; step 12, obtaining the deformation expression of the outer piezoelectric stack structure according to the third kind of piezoelectric equation; step 13, constructing the total displacement expression of the dual piezoelectric stack driving structure according to the deformation expression of the outer piezoelectric stack structure and the deformation expressions output by all inner piezoelectric stack structures.

[0036] Exemplarily, in step 11, the deformation of each internal piezoelectric stack structure is obtained according to the first-order piezoelectric equation and the amplification factor of the lever amplification structure, and the expression for the total deformation of all internal piezoelectric stack structures is obtained as follows: Since the internal piezoelectric stack structure is a square piezoelectric stack, the piezoelectric constitutive relation of its electromechanical coupling can be expressed by the first-kind piezoelectric equation, where the first-kind piezoelectric equation is: (1) In the formula, for stress; For strain; is the electric displacement; is the electric field strength; is the piezoelectric constant; is the dielectric constant; is the elastic compliance coefficient.

[0037] like Figure 8 As shown in the figure, the schematic diagram of the electromechanical coupling of a single square piezoelectric ceramic sheet is shown in the figure. ; ; ; , substituting and simplifying, we can get the deformation of a single square piezoelectric ceramic piece for: (2) In the formula, is the deformation of a single square piezoelectric ceramic piece; is the applied voltage; is the pressure on both ends of the internal piezoelectric stack; is the thickness of a single square piezoelectric ceramic piece; Represents the area of ​​a square piezoelectric ceramic piece.

[0038] Assume that the four internal pressure stack structures are finally assembled, each of which consists of The deformation of a single internal piezoelectric stack structure is the linear superposition of all square piezoelectric ceramic sheets. The initial total deformation of all internal piezoelectric stack structures is: (3) Among them, when the pressure on both ends of the piezoelectric stack When When the displacement When the output force .

[0039] Then the total deformation of all internal piezoelectric stack structures after amplification by the lever amplification structure is: (4) in, It indicates the magnification factor of the lever amplification structure on the total deformation of all internal piezoelectric stack structures.

[0040] Exemplarily, in step 12, the step of obtaining the deformation expression of the external piezoelectric stack structure according to the third kind of piezoelectric equation is: The external piezoelectric stack structure is a cylindrical piezoelectric stack. Each layer of the stack can be regarded as a piezoelectric thin-walled ring oscillator. Considering its polarization along the tangential direction (z axis), the third kind of piezoelectric equation is selected, namely: (5) In the formula, for stress; For strain; is the electric displacement; is the electric field strength; is the open circuit elastic compliance coefficient; is the piezoelectric voltage coefficient; is the free dielectric isolation ratio; For thin-walled annuli: (6) In the formula, is the electric field strength; is the piezoelectric voltage constant; for stress; is the free dielectric isolation ratio; is the electric displacement; For strain; is the open circuit elastic compliance coefficient.

[0041] It can be solved as follows: (7) like Figure 3 As shown, in order to make the polarization uniform, the polarized piezoelectric ring is formed by embedding two arc-shaped electrodes and an even number of arc-shaped piezoelectric ceramic sheets, and the electrodes are connected in parallel.

[0042] From the dielectric constant matrix and the piezoelectric strain constant matrix, the dielectric isolation rate matrix can be obtained: (8) In the formula, is the dielectric constant.

[0043] Piezoelectric Voltage Constant Matrix for: (9) In the formula, is the dielectric constant, is the piezoelectric strain constant.

[0044] From the above piezoelectric voltage constant matrix and dielectric isolation rate matrix, we can get: (10) The open-circuit elastic compliance constant of the piezoelectric ring polarized along the Z axis is: (11) Substituting equation (9) and equation (10) into equation (6), we have , , , the deformation of the single-piece piezoelectric ring along the tangential polarization can be obtained as follows: (12) The deformation of the annular outer piezoelectric stack structure is regarded as the linear superposition of the deformation of the polarized piezoelectric ring. The deformation of the outer piezoelectric stack structure is: (13) The deformation of the outer piezoelectric stack structure is transferred to the inner piezoelectric stack structure through the sleeve in the structure. Therefore, the total displacement generated by the dual piezoelectric stack structure is the linear superposition of the deformation corresponding to the inner piezoelectric stack structure and all the outer piezoelectric stack structures, that is: (14) In the formula, represents the total displacement of the dual piezoelectric stack driving structure; Indicates the total deformation of the internal piezoelectric stack structure; Indicates the deformation of the external piezoelectric stack structure; Indicates the magnification factor of the lever amplification structure on the deformation of the internal piezoelectric stack structure; represents the piezoelectric constant; Represents the area of ​​the square piezoelectric ceramic piece; Represents the area of ​​the arc-shaped ceramic piece within a single polarized piezoelectric ring; Indicates the number of square piezoelectric ceramic pieces in the internal piezoelectric stack structure; Represents the number of polarized piezoelectric rings in the internal piezoelectric stack structure; Indicates the applied voltage; It indicates the short-circuit elastic compliance coefficient of the square piezoelectric ceramic material when the electric field intensity E is constant; Indicates the pressure at both ends of the internal piezoelectric stack; Indicates the pressure at both ends of the external piezoelectric stack; Indicates the thickness of the piezoelectric ceramic stack within a single chip; Indicates the thickness of the single-piece external piezoelectric ceramic stack; Indicates the thickness of a single copper electrode; represents the elastic compliance coefficient of the annular piezoelectric ceramic material when the electric field strength is 0 or constant; wherein, in this embodiment, the pressure at both ends of the external piezoelectric stack is and the pressure at both ends of the internal piezoelectric stack equal.

[0045] It should be noted that, in the no-load state, when the dual piezoelectric stack driving structure is only driven by voltage, the total displacement of the dual piezoelectric stack driving structure at this time is the maximum displacement, that is, the maximum displacement is: (15) In the formula, It represents the maximum displacement of the dual piezoelectric stack drive structure when it is driven only by voltage.

[0046] Step 2, constructing the total equivalent stiffness expression of the dual piezoelectric stack drive structure; Specifically, the steps of constructing the total equivalent stiffness expression of the dual piezoelectric stack driving structure are as follows: Step 21, based on the principle of equivalent stiffness of series structure, obtain the total expression of the equivalent stiffness of all internal piezoelectric stack structures and the expression of the equivalent stiffness of the external piezoelectric stack structure; Step 22, based on the expression of the equivalent stiffness of all internal piezoelectric stack structures and the expression of the equivalent stiffness of the external piezoelectric stack structure; construct the total equivalent stiffness expression of the dual piezoelectric stack driving structure.

[0047] Exemplarily, in step 21, according to the equivalent stiffness principle of the series structure, the steps of obtaining the total expression of the equivalent stiffness of all the inner piezoelectric stack structures and the expression of the equivalent stiffness of the outer piezoelectric stack structure are: Considering the piezoelectric ceramic material Effect, the piezoelectric equation can be simplified to: (16) In the formula, is the electric displacement in the vertical direction, is the stress in the vertical direction, is the strain in the vertical direction, is the electric field in the vertical direction, is the piezoelectric constant, is the elastic compliance coefficient.

[0048] Only the vertical polarization of the piezoelectric stack structure is considered, that is, the polarization of the piezoelectric ceramic material is discussed. When the piezoelectric ceramic is not subject to external constraints and is only under the action of an applied electric field, its strain equation is: (17) in, ; , then the equivalent stiffness expression can be obtained as: (18) in, is the equivalent stiffness coefficient of the piezoelectric ceramic material in the polarization direction; A is the area of ​​the piezoelectric ceramic, and t is the thickness of the piezoelectric ceramic in the polarization direction.

[0049] Apply voltage to piezoelectric ceramics and consider electromechanical coupling. In the mechanical model, according to the equivalent stiffness principle of series structure, the equivalent stiffness of the piezoelectric stack can be expressed as: (19) (20) In the formula, represents the total equivalent stiffness of the piezoelectric stack; It represents the equivalent stiffness of the piezoelectric ceramic piece; represents the equivalent stiffness of the copper electrode; Represents the area of ​​the piezoelectric ceramic sheet; represents the elastic modulus of the copper electrode; Indicates the number of layers of copper electrodes; represents the thickness of the monolithic piezoelectric stack; Indicates the thickness of a single copper electrode; Indicates the number of layers of the piezoelectric stack structure; represents the elastic stiffness coefficient; Considering the actual structure of the dual piezoelectric stack, the four internal piezoelectric stack structures are connected in parallel, and the total equivalent stiffness of the four internal piezoelectric stack structures is The inner piezoelectric stack structure and the outer piezoelectric stack structure are connected in series, so the total equivalent stiffness of the dual piezoelectric stack drive structure is .

[0050] Among them, the total equivalent stiffness of all internal piezoelectric stacks is: (twenty one) Among them, the equivalent stiffness of the external piezoelectric stack is: (twenty two) Among them, the total equivalent stiffness of the dual piezoelectric stack drive structure is: (twenty three) Step 3, constructing a relationship between the design parameters of the dual piezoelectric stack driving structure and the output force of the dual piezoelectric stack driving structure; Specifically, according to the expression of total displacement and total equivalent stiffness, the relationship between the design parameters of the dual piezoelectric stack driving structure and the output force of the dual piezoelectric stack driving structure is constructed, wherein the design parameters are: the amplification factor of the lever amplification structure, the area of ​​the arc-shaped ceramic sheet in a single polarized piezoelectric ring, the area of ​​a single square piezoelectric ceramic sheet, and the number of internal piezoelectric stack structures.

[0051] Exemplarily, the relationship between the design parameters of the dual piezoelectric stack driving structure and the output force of the dual piezoelectric stack driving structure is:

[0052] In the formula, Represents the output force of the dual piezoelectric stack drive structure.

[0053] Step 4, obtaining design parameters when designing a dual piezoelectric stack drive structure; Specifically, according to the relationship between the design parameters of the dual piezoelectric stack driving structure and the output force of the dual piezoelectric stack driving structure, as well as the required output force of the dual piezoelectric stack driving structure, the design parameters when designing the dual piezoelectric stack driving structure are obtained, and the dual piezoelectric stack driving structure is designed.

[0054] The following examples are combined to verify the embedded lever-type dual piezoelectric stack drive structure of the present invention: Step 1: Working conditions requirements: Input voltage , the maximum output displacement of the structure must not be less than , the equivalent stiffness of the structure is not less than , the maximum output force of the structure is not less than N.

[0055] Step 2: Structural design: Thickness of single piezoelectric ceramic , The cross-sectional size of the square internal piezoelectric ceramic is 40*40mm, and the number of internal piezoelectric stack layers is , the inner diameter of the annular outer piezoelectric ceramic , outer diameter , the number of external piezoelectric stack layers .

[0056] Step 3: Calculation and verification: Considering the influence of copper electrode, the elastic compliance constant is , piezoelectric coefficient .

[0057] , meeting the requirements.

[0058] , meeting the requirements.

[0059] , , , meeting the requirements.

[0060] Step 4: Comparative simulation: The displacement changes obtained by using COMSOL software for displacement simulation are as follows Fig.10 As shown, from Fig.10 It can be seen that the overall displacement transmission path of the dual piezoelectric stack meets the design requirements. The displacement of the outer piezoelectric stack structure is transmitted to the bottom of the inner piezoelectric stack structure through the sleeve, superimposed with the displacement generated by the inner piezoelectric stack structure, and then the horizontal lever at the top of the inner piezoelectric stack structure performs secondary displacement amplification. Finally, the output rod connected to the common connection point of the four horizontal levers realizes the displacement output uniformly. Compared with the theoretical value, the relative error of the displacement simulation value is 0.8%, which meets the requirements.

[0061] In this example, when the input voltage is 10V, the maximum output displacement of the piezoelectric drive structure is , the maximum output force is 37721N. The structure is highly sensitive to changes in voltage input, achieving the purpose of significantly controlling the output of the structure through voltage. At the same time, the maximum displacement of the external piezoelectric output is , which is only half of the terminal output displacement. The dual piezoelectric stack structure and lever amplification structure play a good role in amplifying the output value.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An embedded lever-type dual piezoelectric stack drive structure, characterized in that: include: A sleeve (3) is provided with a mounting plate (6) at one end thereof, and a plurality of parallel internal piezoelectric stack structures (5) are evenly distributed on the mounting plate (6) around the center of the mounting plate (6); An annular outer piezoelectric stack structure (2) is sleeved on a sleeve (3), one end of which is connected to the top of the sleeve (3), and the other end of which is connected to a base ring (1), wherein the length of the outer piezoelectric stack structure (2) is greater than that of the sleeve (3); wherein a plurality of inner piezoelectric stack structures (5) are connected in parallel and then in series with the outer piezoelectric stack structure (2); and a lever amplification structure (4) for amplifying the deformation of the internal piezoelectric stack structure (5), comprising a plurality of vertical levers (41), each vertical lever (41) being hinged to a horizontal lever (42) at the top, one end of the vertical lever being fixed to a mounting plate (6) in the sleeve (3), the other end of the vertical lever (41) being hinged to the end of the horizontal lever (42), and the ends of all the horizontal levers (42) facing away from the vertical lever (41) being connected to one point; The top of each internal piezoelectric stack structure (5) is hinged to the bottom of a horizontal lever (42).

2. The embedded lever-type dual piezoelectric stack driving structure according to claim 1, characterized in that: The external piezoelectric stack structure (2) comprises: a plurality of stacked polarized piezoelectric rings, each polarized piezoelectric ring comprising: two arc electrodes and an even number of arc piezoelectric ceramic sheets, the two arc electrodes and the even number of arc piezoelectric ceramic sheets are connected to form a polarized piezoelectric ring, wherein the two arc electrodes are separated by the arc piezoelectric ceramic sheets, the two arc electrodes of the same polarized piezoelectric ring are connected in parallel, and the arc electrodes between adjacent polarized piezoelectric rings are connected in series in sequence.

3. The embedded lever-type dual piezoelectric stack driving structure according to claim 2, characterized in that: The polarized piezoelectric ring includes two arc-shaped electrodes and four arc-shaped piezoelectric ceramic sheets. Every two arc-shaped piezoelectric ceramic sheets are connected to form a piezoelectric ceramic segment. The ends of the two piezoelectric ceramic segments are connected with the arc-shaped electrode.

4. The embedded lever-type dual piezoelectric stack driving structure according to claim 1, characterized in that: The internal piezoelectric stack structure (5) comprises: a plurality of stacked square piezoelectric ceramic sheets, a square electrode being provided between every two adjacent square piezoelectric ceramic sheets, wherein the square piezoelectric ceramic sheets and the square electrodes are connected in series, the plurality of internal piezoelectric stack structures (5) are connected in parallel, and the parallel-connected internal piezoelectric stack structures (5) are connected in series with the external piezoelectric stack structure (2).

5. The embedded lever-type dual piezoelectric stack driving structure according to claim 1, characterized in that: An insulating plate (7) is arranged on the top of the internal piezoelectric stack structure (5); the insulating plate (7) and the bottom of the horizontal lever (42) are hinged, and the common connection point of the horizontal lever (42) is located on the central axis of the sleeve (3).

6. The embedded lever-type dual piezoelectric stack driving structure according to claim 1, characterized in that: A retaining ring is radially arranged at the top end of the sleeve (3), and the retaining ring is sleeved and fixed to the sleeve (3), wherein the top end of the outer piezoelectric stack structure (2) is fixed to the retaining ring.

7. A method for designing an embedded lever-type dual piezoelectric stack drive structure, characterized in that: include: The deformation of each internal piezoelectric stack structure is obtained according to the first-order piezoelectric equation and the amplification factor of the lever amplification structure, and the total deformation expression of all internal piezoelectric stack structures is obtained; According to the third kind of piezoelectric equation, the deformation expression of the external piezoelectric stack structure is obtained; According to the deformation expression of the outer piezoelectric stack structure and the deformation expression of all the inner piezoelectric stack structures output, the total displacement expression of the dual piezoelectric stack driving structure is constructed; According to the equivalent stiffness principle of series structure, the total expression of the equivalent stiffness of all internal piezoelectric stack structures and the expression of the equivalent stiffness of the external piezoelectric stack structure are obtained; According to the expression of equivalent stiffness of all internal piezoelectric stack structures and the expression of equivalent stiffness of external piezoelectric stack structures; Construct the total equivalent stiffness expression of the dual piezoelectric stack drive structure; According to the total displacement expression and the total equivalent stiffness expression, the relationship between the design parameters of the dual piezoelectric stack drive structure and the output force of the dual piezoelectric stack drive structure is constructed, wherein the design parameters are: the magnification of the lever amplification structure, the area of ​​the arc-shaped ceramic piece in a single polarized piezoelectric ring, the area of ​​a single square piezoelectric ceramic piece, and the number of internal piezoelectric stack structures; According to the relationship between the design parameters of the dual piezoelectric stack driving structure and the output force of the dual piezoelectric stack driving structure, as well as the required output force of the dual piezoelectric stack driving structure, the design parameters when designing the dual piezoelectric stack driving structure are obtained, and the dual piezoelectric stack driving structure is designed.

8. The embedded lever-type dual piezoelectric stack driving structure according to claim 7, characterized in that: The total displacement expression of the dual piezoelectric stack driving structure is: In the formula, represents the total displacement of the dual piezoelectric stack driving structure; Indicates the total deformation of the internal piezoelectric stack structure; Indicates the deformation of the external piezoelectric stack structure; Indicates the magnification factor of the lever amplification structure on the deformation of the internal piezoelectric stack structure; Indicates the number of internal piezoelectric stack structures; represents the piezoelectric constant; Represents the area of ​​the square piezoelectric ceramic piece; Represents the area of ​​the arc-shaped ceramic piece within a single polarized piezoelectric ring; Indicates the number of square piezoelectric ceramic pieces in the internal piezoelectric stack structure; Represents the number of polarized piezoelectric rings in the internal piezoelectric stack structure; Indicates the applied voltage; It indicates the short-circuit elastic compliance coefficient of the square piezoelectric ceramic material when the electric field intensity E is constant; Indicates the pressure at both ends of the internal piezoelectric stack; Indicates the pressure at both ends of the external piezoelectric stack; Indicates the thickness of a single square piezoelectric ceramic piece; represents the thickness of a single polarized piezoelectric ring; It represents the elastic compliance coefficient of the annular piezoelectric ceramic material when the electric field strength is 0 or constant.

9. The embedded lever-type dual piezoelectric stack driving structure according to claim 7, characterized in that: The total equivalent stiffness expression of the dual piezoelectric stack drive structure is: In the formula, represents the total equivalent stiffness of the dual piezoelectric stack drive structure; Represents the total equivalent stiffness of all internal piezoelectric stack structures; Represents the total equivalent stiffness of the internal piezoelectric stack structure; Represents the area of ​​the square piezoelectric ceramic piece; Represents the area of ​​the arc-shaped ceramic piece within a single polarized piezoelectric ring; represents the elastic modulus of the copper electrode; It indicates the open circuit elastic stiffness coefficient of the piezoelectric ceramic material when the electric field strength E is zero or constant; represents the number of layers of copper electrodes in the external piezoelectric stack; Indicates the number of layers of copper electrodes in the internal piezoelectric stack; Indicates the thickness of the piezoelectric ceramic stack within a single chip; Indicates the thickness of the single-piece external piezoelectric ceramic stack; Indicates the thickness of a single copper electrode; Indicates the number of external piezoelectric ceramic stacks; Indicates the number of piezoelectric ceramics in the stack.

10. The embedded lever-type dual piezoelectric stack driving structure according to claim 8, characterized in that: The relationship between the amplification factor of the lever amplification structure, the area of ​​the arc-shaped ceramic piece in a single polarized piezoelectric ring, the area of ​​a single square piezoelectric ceramic piece, the number of internal piezoelectric stack structures, and the output force of the dual piezoelectric stack drive structure is as follows: In the formula, represents the output force of the dual piezoelectric stack driving structure; represents the total equivalent stiffness of the dual piezoelectric stack drive structure.

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