Multi-connected-drive piezoelectric actuator

Abstract

The invention discloses a multi-connected drive piezoelectric actuator. The device comprises at least three piezoelectric bidirectional stacks, a pre-tightening mechanism, a displacement mechanism, a multi-wire interface and a shell. Two-degree-of-freedom deformation is generated by piezoelectric bi-directional stacks with micro-nano displacement capacity, and the piezoelectric bi-directional stacks act on the displacement mechanism at multi-point positions and enable the displacement mechanism to output continuous displacement. A structure larger than a traditional two-connection drive structure is innovatively constructed, and a control strategy of scanning motion is used for the structure. The function of the piezoelectric stack actuator breaks through the shackle that the current piezoelectric stack actuator and the piezoelectric stepping motor are influenced by the traditional control thinking, and the piezoelectric stack actuator has the practical advantages of high precision, small size, easy assembly, electrical standardization and the like. The piezoelectric actuator is a research and development achievement leading the world in the piezoelectric actuation industry and has great contribution to the marketization process of the ultra-precision engineering field.

Description

Technical Field

[0001] The present invention belongs to the technical field of precision mechatronic engineering. Specifically, it relates to a multi-connected piezoelectric actuator. Background Art

[0002] A piezoelectric actuator is a precision actuator that utilizes piezoelectric actuation as its output, and has advantages such as high precision, fast response, small volume, low energy consumption, and non-magnetic properties. At present, the market generally believes that in ultra-precision engineering fields such as the semiconductor industry and the detection industry, piezoelectric actuators have gradually obtained wider applications due to their performance. Especially in a vacuum environment, it is an ideal product to replace magnetoelectric motors.

[0003] However, existing piezoelectric actuators are restricted by individual inherent drawbacks and cannot fully enter the substitution process. For the three important basic piezoelectric actuator products, the stacked actuator has a large output force and high precision, but its stroke is limited to the micron level; the flexure hinge actuator can increase the stroke to the millimeter level, but at the cost of stiffness and still cannot meet the large stroke requirements; the stepping actuator significantly increases the stroke while retaining precision and stiffness, but its stepping mode cannot perform the scanning motion required by actual equipment such as lithography machines from a mechanism perspective. Therefore, new technologies for piezoelectric actuators are developed to enable them to obtain the three-in-one functions of long stroke, high precision, and performable scanning motion, further accelerating the substitution process in cutting-edge fields. Summary of the Invention

[0004] Aiming at the deficiencies of the above-mentioned existing technologies, the purpose of the present invention is to provide a multi-connected piezoelectric actuator. Through the control strategy of the multi-connected piezoelectric actuator cooperating with the scanning motion, the present invention obtains a multi-connected structure, whose realized functions break the shackles formed by the current piezoelectric stacked actuator and piezoelectric stepping motor under the influence of traditional control thinking, and has high precision, small volume, easy assembly, electrical standardization, etc., and can be widely applied to the fields of piezoelectric actuation and ultra-precision engineering.

[0005] The technical solution of the present invention is specifically introduced as follows.

[0006] The present invention provides a multi-connected piezoelectric actuator, which includes at least three piezoelectric two-way stacks, a pre-tightening mechanism, a displacement mechanism, a multi-line interface, and a housing; the piezoelectric two-way stacks are fixedly connected to the pre-tightening mechanism, and the pre-tightening mechanism is fixedly connected to the housing; the deformation of the piezoelectric two-way stacks can act on the displacement mechanism, so that it outputs a displacement equal to the deformation amount in a specified direction due to the deformation of the piezoelectric two-way stacks; the multi-line interface can drive and control the piezoelectric two-way stacks to complete continuous motion after connecting the pins.

[0007] Specifically, the piezoelectric two-way stack includes piezoelectric stacks in two deformation directions, and their two deformation states do not interfere with each other. Preferably, the two deformation directions of the piezoelectric stack are orthogonal.

[0008] Specifically, the preloading mechanism enables the piezoelectric bimorph stack to have a preloading force that maximizes piezoelectric actuation when contacting the displacement mechanism. The polarization direction of the piezoelectric stack is consistent with the preloading direction of the preloading mechanism. Preferably, the preloading mechanism uses a flexible mechanism or elastic material processed by wire cutting.

[0009] Specifically, the displacement mechanism includes a mover and a guide rail. The contact surface between the mover and the piezoelectric bimorph stack exhibits wear-resistant surface characteristics, and the movement direction of the guide rail is the same as the deformation direction of one of the piezoelectric stacks. Optionally, when the fixed movement direction is satisfied by other means, the displacement mechanism does not use a guide rail.

[0010] Preferably, the movement direction of the mover is parallel or orthogonal to the positioning surface of the housing.

[0011] Preferably, the multi-line interface uses a common interface that meets the interchangeability conditions, and the number of its pins is not less than 6.

[0012] Specifically, the volume of the housing satisfies the layout of the piezoelectric bimorph stack, the preloading mechanism, the displacement mechanism, and the multi-line interface, with positioning holes, a flat positioning surface, chamfering and deburring of the edges, etc. Preferably, when the number of housings is greater than 1, one main housing is used to fixedly connect the preloading mechanism.

[0013] The working principle of the present invention is as follows: for a multi-connected piezoelectric actuator, no less than 6 piezoelectric stacks cooperate in deformation under a control strategy, so that no less than 3 piezoelectric bimorph stacks composed of them can act on the displacement mechanism in at least three steps in a cycle, and finally the mover outputs a coherent displacement equal to the deformation speed. The control strategy must drive and control at least three batches of the piezoelectric bimorph stacks, that is, at least six voltage signals directly related to the piezoelectric stacks, so as to meet the condition that at least one piezoelectric bimorph stack is acting on the displacement mechanism to generate movement. Therefore, at any moment, the displacement mechanism can output a coherent and constant-speed displacement, that is, the multi-connected piezoelectric actuator is performing a scanning movement.

[0014] Embodiment 1 and Embodiment 2 of the present invention each provide a multi-connected piezoelectric actuator. Among them, in Embodiment 1, 3 piezoelectric bimorph stacks are used, the preloading mechanism uses a wire-cut flexible hinge, the displacement mechanism is a mover and a guide rail, the movement direction is z in a certain direction, the multi-line interface is a circular 7-pin interface, the housing is semi-open and can be assembled to a vertical plane through positioning holes, and a corresponding control strategy is described; in Embodiment 2, 8 piezoelectric stacks are used, the preloading mechanism uses elastic rubber, the displacement mechanism does not use a guide rail, the movement direction is x in a certain direction, the multi-line interface is a 2×4 array pin interface, and there are three housings that form a closed structure, and a corresponding control strategy is attached.

[0015] Compared with existing piezoelectric actuators, the beneficial effects of the present invention are as follows: the present invention constructs a driving structure that is larger than the structure of traditional dual-drive. When using a multi-connected drive piezoelectric actuator with the structural characteristics described in the present invention, it can use a reasonable control strategy to perform a scanning motion that existing piezoelectric actuators cannot complete. The present invention simultaneously has the characteristics of the highest precision and the longest stroke of piezoelectric actuation, as well as the ability to perform a scanning motion, which meets the market demand in the field of particulate bonding ultra-precision engineering, and significantly contributes to the substitution application of piezoelectric actuators in industries such as semiconductors, aerospace, and inspection and measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 FIG. is a schematic structural diagram of a multi-connected drive piezoelectric actuator provided in Embodiment 1 of the present invention.

[0017] Figure 2 FIG. is a schematic diagram of a control strategy provided in Embodiment 1 of the present invention.

[0018] Figure 3 FIG. is a schematic structural diagram of a multi-connected drive piezoelectric actuator provided in Embodiment 2 of the present invention.

[0019] Figure 4 FIG. is a schematic diagram of a control strategy provided in Embodiment 2 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] The present invention will be further described in detail below with reference to the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. In addition, it should be noted that for the sake of description, only parts related to the present invention are shown in the drawings, rather than all the structures.

[0021] In the description of the embodiments of the present invention, unless otherwise clearly defined and limited, for example, the terms "connected", "connected", and "fixed" should be understood in a broad sense, which can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0022] In the embodiments of the present invention, unless otherwise clearly defined and limited, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the horizontal height of the first feature is higher than that of the second feature. The first feature being "below", "beneath" and "underneath" the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the horizontal height of the first feature is less than that of the second feature.

[0023] In the description of the embodiments of the present invention, the orientation or positional relationships such as "above", "below", "right", "inside", "outside", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of description and simplifying the operation, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention. In addition, the terms "first" and "second" are only used for differentiation in description and have no special meaning.

[0024] Embodiment 1

[0025] Figure 1 It is a schematic structural diagram of a multi-connected piezoelectric actuator provided by Embodiment 1 of the present invention. The figure shows the main structures such as three piezoelectric bimorph stacks 10, a pre-tightening mechanism 20, a displacement mechanism 30, a multi-wire interface 40, and a housing 50. The connecting parts are not shown in the figure. Figure 1 Above and below on the left are the top view and the front view of Embodiment 1 respectively; Figure 1 On the upper right is the three-dimensional display diagram of Embodiment 1; Figure 1 On the lower right is the schematic diagram of the piezoelectric bimorph stack 10 in Embodiment 1.

[0026] Specifically, the three piezoelectric bimorph stacks 10 are respectively driving batches A, B, and C from top to bottom, and the connection positions with the pre-tightening mechanism 20 on one side are on the same line. The pre-tightening mechanism 20 is a wire-cut flexible mechanism and is fixedly connected to the housing 50 in a y directional fixed connection manner. Each piezoelectric bimorph stack 10 is composed of a piezoelectric stack 11 and a piezoelectric stack 12, corresponding to two deformation directions respectively, as shown by the arrows. In Embodiment 1, the piezoelectric stacks 11 and 12 use lead zirconate titanate PZT materials with polarization properties of d33 and d15, and the deformation directions correspond to the z direction and the x direction of the three-dimensional display diagram respectively.

[0027] Specifically, the displacement mechanism 30 is composed of a guide rail 31 and a mover 32. In the first embodiment, the selected guide rail 31 is a ball linear guide rail. The fixed end of the guide rail 31 is fixedly connected to the housing 50, and the sliding end is connected to the mover 32. In the first embodiment, the materials of the mover 21 and the housing 30 are aluminum alloy. The multi-wire interface 40 is a 7-pin, and its interface position is set on the lower right side of the housing 50 in the front view. During actual use, a matching plug is connected to the multi-wire interface 40, and an external driving and controlling device provides a loading voltage for the piezoelectric bimorph 10; the piezoelectric bimorph 10 deforms due to the loading voltage, and then the mover 32 generates a displacement in the direction of the guide rail 31 due to the piezoelectric bimorph 10.

[0028] Figure 2 It is a schematic diagram of a control strategy provided by the first embodiment of the present invention. Figure 2 The actions of three steps within one cycle are shown thereon, and they are vertically corresponding to Figure 2 the displacement values in the two directions shown below. Among them, the voltage of the piezoelectric stack 11 is shown in x group, and the positive value represents x the positive direction of the z direction. The voltage of the piezoelectric stack 12 is shown in z group, and the positive value represents

[0029] Embodiment 2

[0030] Figure 3 It is a schematic structural diagram of a multi-connected drive piezoelectric actuator provided by the second embodiment of the present invention. The figure shows the main structures such as eight piezoelectric bimorphs 10, a pre-tightening mechanism 20, a displacement mechanism 30, a multi-wire interface 40, and a housing 50. The connecting piece is not shown in the figure. Figure 3 On the left and right are the three-dimensional display diagrams of the presence and absence of the housing 52 and the housing 53 of the second embodiment; Figure 3 Below is the top view and side view of the second embodiment without the housing 52 and the housing 53.

[0031] Specifically, the eight piezoelectric bimorphs 10 are symmetrically arranged up and down in the top view, and are divided into four driving batches of AE, BF, CG, and DH. The connection positions of one side with the pre-tightening mechanism 20 are on the same line. The pre-tightening mechanism 20 is an elastic rubber and is bonded to the housing 50. The piezoelectric bimorphs 10 used are the same as those in the first embodiment, and the deformation directions correspond to x, yTwo directions. The displacement mechanism 30 does not use a guide rail, and it itself is the mover clamped from above and below. The multi-line interface 40 has 8-wire pins, and its interface position is led outside the housing 50 through wires.

[0032] Figure 4 It is a schematic diagram of a control strategy provided by the second embodiment of the present invention. Figure 4 The actions of four steps within one cycle are shown above, and the displacement values in the following two directions are vertically corresponding. Among them, the voltage of the piezoelectric stack 11 is shown in y group, and a positive value represents y the positive direction of the x direction. The voltage of the piezoelectric stack 12 is shown in x group, and a positive value represents x the positive direction of the

[0033] It should be noted that in the piezoelectric bi-directional stack in other embodiments, it can be composed of other reasonable piezoelectric materials and structures; the displacement mechanism, multi-line interface, housing, etc. can also be of other reasonable models and shapes; in the control strategies used in other embodiments, other trajectories with the same function can also be selected, as long as the necessary conditions proposed in the content of the present invention are satisfied.

[0034] Note that the above are only reasonable embodiments of the present invention and the technical principles applied. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described here, and various obvious changes, re-adjustments, combinations, and substitutions can be made by those skilled in the art without departing from the protection scope of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments. Without departing from the concept of the present invention, more other equivalent embodiments can be included, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A multi-connected piezoelectric actuator, characterized in that, It includes at least three piezoelectric bimorph stacks, a preloading mechanism, a displacement mechanism, a multi-wire interface and a housing; the preloading mechanism is fixedly connected to the housing, and the piezoelectric bimorph stacks are fixedly connected to the preloading mechanism; during operation, the deformation of the piezoelectric bimorph stacks acts on the displacement mechanism, and the displacement mechanism moves in a specified direction by an amount equal to its displacement due to the deformation of the piezoelectric bimorph stacks, and the multi-wire interface is used for standardized wiring to drive and control the piezoelectric bimorph stacks.

2. The multi-connected piezoelectric actuator according to claim 1, wherein The piezoelectric bimorph stack includes piezoelectric stacks in two deformation directions, and their two deformation states do not interfere with each other.

3. The multi-connected piezoelectric actuator according to claim 2, wherein The two deformation directions of the piezoelectric stack are orthogonal.

4. The multi-connected piezoelectric actuator according to claim 1, wherein The preloading mechanism enables the piezoelectric bimorph stack to have a preloading force that maximizes piezoelectric actuation when contacting the displacement mechanism.

5. The multi-connected piezoelectric actuator according to claim 4, characterized in that, The preloading mechanism uses wire electrical discharge machining for flexible mechanisms or elastic materials.

6. The multi-connected piezoelectric actuator according to claim 1, wherein The displacement mechanism includes a mover, and the contact surface between the mover and the piezoelectric bimorph stack exhibits wear-resistant surface characteristics, and the movement direction of the mover is the same as the deformation direction of one of the piezoelectric stacks.

7. The multi-connected piezoelectric actuator according to claim 6, characterized in that, In the displacement mechanism, the movement direction of the mover is parallel or orthogonal to the positioning surface of the housing.

8. The multi-connected piezoelectric actuator according to claim 1, wherein The multi-wire interface uses an electrical standard interface, and the number of its pins is greater than or equal to the number of piezoelectric stacks that the piezoelectric bimorph stack should drive in batches.

9. The multi-connected piezoelectric actuator according to claim 1, wherein The piezoelectric bimorph stacks cooperate in deformation under a control strategy, so that at least three piezoelectric bimorph stacks composed of them act on the displacement mechanism in at least three steps in a cycle, and finally the mover outputs a coherent displacement equal to the deformation speed.

10. The multi-connected piezoelectric actuator according to claim 9, characterized in that, The control strategy is as follows: Drive and control at least three batches of piezoelectric bimorph stacks, that is, at least six voltage signals directly related to the piezoelectric stacks, so that the condition that at least one piezoelectric bimorph stack is acting on the displacement mechanism to generate movement is satisfied.

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