A bidirectional stepping piezoelectric driver

Abstract

The application discloses a bidirectional stepping piezoelectric driver, which comprises a driving assembly, a moving assembly, a pre-tightening assembly and a supporting assembly. The driving assembly comprises two groups of piezoelectric units, each group of piezoelectric units comprises three piezoelectric ceramic legs, each piezoelectric ceramic leg comprises a longitudinal telescopic piezoelectric stack and a transverse shear piezoelectric stack, the three piezoelectric ceramic legs of each group of piezoelectric units are distributed in a plane in a form of an equilateral triangle, and the six piezoelectric ceramic legs are distributed in a plane in a form of a regular hexagon. The distribution mode can improve the stability of the movement of the moving assembly, the structure is compact, and the transverse shear deformation directions of the transverse shear piezoelectric stacks of the two groups of piezoelectric units are orthogonal in the plane. When the driver moves, one group of piezoelectric units generates clamping motion, and the other group of piezoelectric units generates stepping motion. Under the voltage time sequence control, the two groups of piezoelectric units can realize the stepping motion of the driver in two orthogonal directions.

Description

Technical Field

[0001] This application relates to the field of piezoelectric drive technology, and in particular to a bidirectional stepping piezoelectric driver. Background Technology

[0002] Piezoelectric actuators are actuators designed to output precise motion by utilizing the inverse piezoelectric effect of piezoelectric materials. With their excellent performance such as high precision, long stroke, and fast response, piezoelectric actuators are widely used in many fields.

[0003] Traditional piezoelectric actuators can typically only achieve linear motion output in a single direction. With the development of technology, the limitation of a single degree of freedom restricts the application of piezoelectric actuators in fields such as micro-robotics, medical devices, and testing equipment. Therefore, how to expand the application of piezoelectric actuators is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] The purpose of this application is to provide a bidirectional stepping piezoelectric actuator that can achieve stepping motion output in two orthogonal directions, and has a compact structure and stable operation.

[0005] To achieve the above objectives, this application provides the following technical solution:

[0006] A bidirectional stepping piezoelectric actuator includes: a drive component, a motion component, a preload component, and a support component. The support component supports the drive component and the preload component. The preload component applies a preload force toward the drive component to the motion component. The drive component drives the motion component to move.

[0007] The driving assembly includes two sets of piezoelectric units. Each set of piezoelectric units includes multiple piezoelectric ceramic legs. Each piezoelectric ceramic leg includes a longitudinally telescopic piezoelectric stack and a transversely shearing piezoelectric stack. The transverse shearing deformation direction of the transversely shearing piezoelectric stack of one set of piezoelectric units is orthogonal in the plane to the transverse shearing deformation direction of the transversely shearing piezoelectric stack of the other set of piezoelectric units.

[0008] During stepping motion, one set of piezoelectric units is used to clamp the moving component, while the other set of piezoelectric units is used to drive the moving component.

[0009] Preferably, the plurality of piezoelectric ceramic legs are evenly distributed along the circumferential direction, wherein a piezoelectric ceramic leg of another set of piezoelectric units is provided between two adjacent piezoelectric ceramic legs of a set of piezoelectric units.

[0010] Preferably, each of the two sets of piezoelectric units includes three piezoelectric ceramic legs, and the three piezoelectric ceramic legs located in the same set of piezoelectric units are arranged in an equilateral triangle.

[0011] Preferably, the preload assembly includes a preload screw, a preload disc spring, and a pressure plate. The pressure plate has a rolling part below it for contacting the upper surface of the moving assembly. The preload disc spring is sleeved on the preload screw and located above the pressure plate. The preload screw passes through the pressure plate and the moving assembly from top to bottom and is fixed to the support assembly so as to apply a downward preload force to the moving assembly through the preload disc spring.

[0012] Preferably, the rolling part is a planar bearing, the upper end of the planar bearing is connected to the lower end of the pressure plate, and the lower end of the planar bearing is in contact with the upper surface of the motion component.

[0013] Preferably, the preload assembly further includes a flat washer disposed between the head of the preload screw and the preload disc spring.

[0014] Preferably, the piezoelectric ceramic leg further includes a wear-resistant ceramic sheet, and the longitudinal telescopic piezoelectric stack, the transverse shear piezoelectric stack, and the wear-resistant ceramic sheet are bonded together in series by epoxy resin structural adhesive.

[0015] Preferably, the motion component is a motion platform, the support component is a support plate, and the drive component is located between the support plate and the motion platform.

[0016] Compared with existing technologies, the above technical solution has the following advantages:

[0017] 1. Compared with traditional single-degree-of-freedom piezoelectric actuators, this application can realize continuous and precise stepping motion in two orthogonal directions in a plane.

[0018] 2. This application uses two sets of drive units as drive components. During stepping motion, multiple piezoelectric ceramics work simultaneously, resulting in greater motion output stiffness and generating greater driving force. At the same time, when the piezoelectric actuator is powered off, it can still maintain a large preload through the preload component. A large static friction force can be generated between the moving component and multiple piezoelectric ceramic legs to ensure that the piezoelectric actuator has a high power-off holding force. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of a bidirectional stepper piezoelectric actuator;

[0021] Figure 2 This is a schematic cross-sectional view of a bidirectional stepping piezoelectric actuator in the ZY section.

[0022] Figure 3 This is a schematic cross-sectional view of a bidirectional stepper piezoelectric actuator at section ZX.

[0023] Figure 4 A schematic diagram of the structure of a bidirectional stepper piezoelectric actuator after the preload assembly has been removed;

[0024] Figure 5 This is a diagram showing the distribution of the six piezoelectric ceramic legs of a bidirectional stepper piezoelectric actuator.

[0025] Figure 6 This is a schematic diagram of the piezoelectric ceramic leg.

[0026] Figure 7 This is a schematic diagram of the stepping motion process of a bidirectional stepping piezoelectric actuator in the X+ direction.

[0027] Figure 8 This is a schematic diagram of the stepping motion process of a bidirectional stepping piezoelectric actuator in the Y+ direction. Detailed Implementation

[0028] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0029] Please refer to Figures 1-6 This application provides a bidirectional stepping piezoelectric actuator, comprising: a driving component, a motion component, a preload component, and a support component. The support component supports the driving component and the preload component. The preload component applies a preload force to the motion component toward the driving component. The driving component drives the motion component to move. The motion component is preferably a motion platform 6, and the support component is preferably a base 9. The driving component is located between the base 9 and the motion platform 6. The driving component includes two sets of piezoelectric units, each set of piezoelectric units including multiple piezoelectric ceramic legs. Each piezoelectric ceramic leg includes a longitudinally telescopic piezoelectric stack and a transversely shearing piezoelectric stack. The piezoelectric ceramic leg also includes a wear-resistant ceramic sheet u, such as... Figure 6As shown, the longitudinally telescopic piezoelectric stack d, the transversely shearing piezoelectric stack m, and the wear-resistant ceramic sheet u are bonded in series with epoxy resin structural adhesive. The wear-resistant ceramic sheet u can improve the wear resistance of the piezoelectric ceramic legs, thereby ensuring their wear resistance. The transverse shear deformation direction of one set of piezoelectric units' transverse shearing piezoelectric stacks is orthogonal in the plane to the transverse shear deformation direction of the other set of piezoelectric units' transverse shearing piezoelectric stacks. During the stepping motion of the piezoelectric actuator, one set of piezoelectric units generates clamping motion, and the other set of piezoelectric units generates driving motion. Under voltage timing control, the two sets of piezoelectric units can achieve stable stepping motion of the piezoelectric actuator in two orthogonal directions.

[0030] To further improve the motion stability of the piezoelectric actuator, in this embodiment, multiple piezoelectric ceramic legs are evenly distributed along the circumferential direction, and a piezoelectric ceramic leg of another set of piezoelectric units is provided between two adjacent piezoelectric ceramic legs of one set of piezoelectric units. For example Figure 5 As shown, each of the two sets of piezoelectric units includes three piezoelectric ceramic legs. The three piezoelectric ceramic legs in the same set of piezoelectric units are arranged in an equilateral triangle, that is, the six piezoelectric ceramic legs are arranged in a regular hexagon in the plane. This distribution can improve the smoothness of the movement of the moving components and also results in a compact structure. In addition, each of the two sets of piezoelectric units may also include two or more piezoelectric ceramic legs, which can be selected according to actual needs.

[0031] In some embodiments, such as Figure 2 and Figure 3 As shown, the preload assembly includes a preload screw 1, a flat washer 2, a preload disc spring 3, and a pressure plate 4. A rolling part is provided below the pressure plate 4 for contacting the upper surface of the moving component. The rolling part is preferably a planar bearing 5. The upper end of the planar bearing 5 is connected to the lower end of the pressure plate 4, and the lower end of the planar bearing 5 contacts the upper surface of the moving component. The planar bearing 5 can reduce the wear of the moving component. The planar bearing 5 includes multiple balls 5A and ball supports 5B. The multiple balls 5A maintain their relative positions under the constraint of the ball supports 5B. A circumferentially distributed V-groove is provided below the pressure plate, and the V-groove interacts with the balls. 5A contact is used to limit the relative movement between the plane bearing 5 and the pressure plate 4; the preload disc spring 3 is sleeved on the preload screw 1 and located above the pressure plate 4; the flat washer 2 is set between the head of the preload screw 1 and the preload disc spring 3; the preload screw 1 passes through the pressure plate 4 and the moving assembly from top to bottom and is fixed on the support assembly so as to apply a downward preload force to the moving assembly through the preload disc spring 3; the preload assembly can improve the overall rigidity of the driver; after the preload screw 1 is threadedly connected and fixed to the base 9, the pressure plate 4 and the plane bearing 5 do not have relative positional changes in the X and Y directions relative to the base 9.

[0032] After the preload screw 1 is tightened to the base 9 via a threaded connection, the compressed preload disc spring 3 deforms δh in the Z direction, thereby generating a preload force, which is then applied by F. N This can be calculated using the following formula:

[0033] F N =K*δh

[0034] In the formula, K is the compression stiffness of the preloaded disc spring 3.

[0035] Preload F N The motion platform 6 is pressed against plane I by the pre-tightening plate 3 and the plane bearing 5, resulting in frictional coupling between the lower surface of the motion platform 6 and plane I. The maximum static friction force between the lower surface of the motion platform 6 and plane I can be expressed as:

[0036] f max =μ*F N

[0037] In the formula, μ is the static friction coefficient between the lower surface of the motion platform 6 and the plane I.

[0038] To facilitate understanding the working principle of the bidirectional stepper piezoelectric actuator, the following explanation uses the X+ and Y+ directions as examples. To distinguish the two sets of piezoelectric units, they are designated as the first piezoelectric unit 7 and the second piezoelectric unit 8, respectively. The three piezoelectric ceramic legs of the first piezoelectric unit 7 are designated as 7A, 7B, and 7C, and the three piezoelectric ceramic legs of the second piezoelectric unit 8 are designated as 8A, 8B, and 8C. 7A, 8B, 7C, 8A, 7B, and 8C are arranged sequentially in a clockwise direction when viewed from above. The driving voltage for the longitudinal telescopic piezoelectric stack of the first piezoelectric unit 7 is U1. That is, under the action of the driving voltage U1, the longitudinal telescopic piezoelectric stack of the piezoelectric ceramic legs 7A, 8B, and 7C can generate a shape parallel to the Z-axis. The driving voltage for the transverse shear piezoelectric stack of the first piezoelectric unit 7 is U2, meaning that the transverse shear piezoelectric stack of piezoelectric ceramic legs 7A, 7B, and 7C can produce shear deformation parallel to the Y-axis under the action of driving voltage U2; the driving voltage for the longitudinal telescopic piezoelectric stack of the second piezoelectric unit 8 is U3, meaning that the longitudinal telescopic piezoelectric stack of piezoelectric ceramic legs 8A, 7B, and 8C can produce telescopic deformation parallel to the Z-axis under the action of driving voltage U3; the driving voltage for the transverse shear piezoelectric stack of the second piezoelectric unit 8 is U4, meaning that the transverse shear piezoelectric stack of piezoelectric ceramic legs 8A, 7B, and 8C can produce shear deformation parallel to the X-axis under the action of driving voltage U4.

[0039] When the piezoelectric actuator is static, the lower surface of the motion platform 6 is in direct contact with the plane I formed by the six wear-resistant ceramic sheets at the upper ends of the piezoelectric ceramic legs 7A, 7B, 7C, 8A, 8B, and 8C, and the upper surface of the motion platform 6 is in contact with the ball 5A of the plane bearing 5.

[0040] When the piezoelectric actuator is in dynamic motion, the plane II formed by the three wear-resistant ceramic sheets at the upper ends of the three ceramic legs 7A, 7B and 7C of the first piezoelectric unit 7 is no longer coplanar with the plane III formed by the three wear-resistant ceramic sheets at the upper ends of the three ceramic legs 8A, 8B and 8C of the second piezoelectric unit 8; plane II and plane III alternately contact the lower surface of the motion platform 6, driving the motion platform 6 to move in the X / Y direction.

[0041] See appendix Figure 7 The process of the driver stepping in the X+ direction is as follows:

[0042] Initially, the driver is static, and the first piezoelectric unit 7 and the second piezoelectric unit 8 have no voltage action;

[0043] a. U2 and U3 maintain zero voltage. The first piezoelectric unit 7 is driven by U1 to generate Z-direction elongation deformation, and the second piezoelectric unit 8 is driven by U4 to generate X-direction shear deformation. Thus, the first piezoelectric unit 7 clamps the motion platform 6, and the second piezoelectric unit 8 does not contact the motion platform.

[0044] b. U2 remains at zero voltage, while U1 and U4 remain unchanged. U3 drives the second piezoelectric unit 8 to generate Z-direction elongation deformation. At this time, the first piezoelectric unit 7 and the second piezoelectric unit 8 simultaneously achieve clamping of the motion platform 6.

[0045] c. U2 maintains zero voltage, U3 remains unchanged, and the first piezoelectric unit 7 is driven by U1 to generate Z-direction shortening deformation. At the same time, the second piezoelectric unit 8 is driven by U4 to generate X-direction shear deformation. Then, under the action of friction, the second piezoelectric unit 8 drives the motion platform 6 to move to the right by 1 step ΔX.

[0046] d. U2 maintains zero voltage, while U3 and U4 remain unchanged. U1 drives the first piezoelectric unit 7 to generate Z-direction elongation deformation. At this time, the first piezoelectric unit 7 and the second piezoelectric unit 8 simultaneously achieve clamping of the motion platform 6.

[0047] e. U2 maintains zero voltage, while U1 and U4 remain unchanged. U3 drives the second piezoelectric unit 8 to generate Z-direction shortening deformation, which in turn drives the first piezoelectric unit 7 to achieve clamping of the motion platform 6.

[0048] See appendix Figure 7 After completing the abcdea process, the bidirectional stepper piezoelectric actuator moves its motion platform in the X+ direction by a step length ΔX.

[0049] See appendix Figure 7 By repeatedly performing the abcdea process, continuous stepping motion of the bidirectional stepper piezoelectric actuator in the X+ direction can be achieved.

[0050] See appendix Figure 7 The aedcba process can be repeated cyclically to achieve continuous stepping motion of the bidirectional stepping piezoelectric actuator in the X-direction.

[0051] See appendix Figure 8 When the piezoelectric actuator moves in the Y direction, the drive unit 8 acts as a clamp, that is, it keeps the position of the motion platform 6 stationary; the first piezoelectric unit 7 acts as a drive, that is, it drives the motion platform 6 to move in the Y direction.

[0052] See appendix Figure 8 The process of the piezoelectric actuator stepping in the Y+ direction is as follows:

[0053] Initially, the piezoelectric actuator is static, and the first piezoelectric unit 7 and the second piezoelectric unit 8 have no voltage applied.

[0054] A. U1 and U4 maintain zero voltage. The second piezoelectric unit 8 is driven by U3 to generate Z-direction elongation deformation, while the first piezoelectric unit 7 is driven by U2 to generate Y-direction shear deformation. Thus, the second piezoelectric unit 8 clamps the motion platform 6, and the first piezoelectric unit 7 does not contact the motion platform.

[0055] B. U4 maintains zero voltage, U2 and U3 remain unchanged, and the first piezoelectric unit 7 is driven by U1 to generate Z-direction elongation deformation. At this time, the first piezoelectric unit 7 and the second piezoelectric unit 8 simultaneously achieve the clamping of the motion platform 6.

[0056] C. With U4 maintaining zero voltage and U1 remaining unchanged, the second piezoelectric unit 8 is driven by U3 to generate Z-direction shortening deformation, while the first piezoelectric unit 7 is driven by U2 to generate Y-direction Y+ shear deformation. Under the action of friction, the first piezoelectric unit 7 drives the motion platform 6 to move to the right by 1 step length ΔY.

[0057] D and U4 maintain zero voltage, while U1 and U2 remain unchanged. U3 drives the second piezoelectric unit 8 to generate Z-direction elongation deformation. At this time, the first piezoelectric unit 7 and the second piezoelectric unit 8 simultaneously achieve clamping of the motion platform 6.

[0058] E and U4 maintain zero voltage, while U2 and U3 remain unchanged. U1 drives the first piezoelectric unit 7 to generate Z-direction shortening deformation, which in turn drives the second piezoelectric unit 8 to achieve clamping of the motion platform 6.

[0059] See appendix Figure 8 After completing the above ABCDEA process, the bidirectional stepper piezoelectric actuator moves its motion platform in the Y+ direction by one step length ΔY.

[0060] See appendix Figure 8By repeatedly performing the ABCDEA process, continuous stepping motion in the Y+ direction of the bidirectional stepping piezoelectric actuator can be achieved.

[0061] See appendix Figure 8 The AEDCBA process can be repeated cyclically to achieve continuous stepping motion of the bidirectional stepping piezoelectric actuator in the Y direction.

[0062] When the driver moves in the X direction, the frictional force F between plane Ⅲ and motion platform 6 fx The drive platform 6 generates stepping motion; when the driver moves in the Y direction, the frictional force F between plane II and the drive platform 6... fy The driving motion platform 6 generates stepping motion; theoretically, the frictional thrust during X-axis and Y-axis motion is equal, and the following relationship applies:

[0063] F fx =F fy =F f =f max

[0064] The ability of the motion platform 6 to drive the load motion when the driver is stepping in the X direction is expressed by F. X The term F represents the driving force of the new type of driver in the X direction; when the driver moves in the Y direction, the ability of the motion platform 6 to drive the load is represented by F. X This indicates the driving force in the Y direction of the new driver; the driving forces in the X and Y directions of the new driver can be calculated using the following formula:

[0065]

[0066] Where f is the rolling friction resistance between the upper surface of the motion platform 6 and the planar bearing 5 when the driver is in motion.

[0067] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0068] The foregoing has provided a detailed description of a bidirectional stepping piezoelectric actuator provided in this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core ideas of this application. It should be noted that those skilled in the art can make various improvements and modifications to this application without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. A bidirectional stepping piezoelectric actuator, characterized in that, include: The device includes a drive assembly, a motion assembly, a preload assembly, and a support assembly, wherein the support assembly supports the drive assembly and the preload assembly, the preload assembly applies a preload force toward the drive assembly to the motion assembly, and the drive assembly drives the motion assembly to move. The driving assembly includes two sets of piezoelectric units. Each set of piezoelectric units includes multiple piezoelectric ceramic legs. Each piezoelectric ceramic leg includes a longitudinally telescopic piezoelectric stack and a transversely shearing piezoelectric stack. The transverse shearing deformation direction of the transversely shearing piezoelectric stack of one set of piezoelectric units is orthogonal in the plane to the transverse shearing deformation direction of the transversely shearing piezoelectric stack of the other set of piezoelectric units. During stepping motion, one set of piezoelectric units is used to clamp the moving component, while the other set of piezoelectric units is used to drive the moving component.

2. The bidirectional stepping piezoelectric actuator according to claim 1, characterized in that, The piezoelectric ceramic legs are evenly distributed along the circumference, and between two adjacent piezoelectric ceramic legs of one group of piezoelectric units, there is a piezoelectric ceramic leg of another group of piezoelectric units.

3. The bidirectional stepping piezoelectric actuator according to claim 2, characterized in that, Each of the two sets of piezoelectric units includes three piezoelectric ceramic legs, and the three piezoelectric ceramic legs in the same set of piezoelectric units are arranged in an equilateral triangle.

4. The bidirectional stepping piezoelectric actuator according to claim 1, characterized in that, The preload assembly includes a preload screw, a preload disc spring, and a pressure plate. The pressure plate has a rolling part below it for contacting the upper surface of the moving assembly. The preload disc spring is sleeved on the preload screw and located above the pressure plate. The preload screw passes through the pressure plate and the moving assembly from top to bottom and is fixed to the support assembly so as to apply a downward preload force to the moving assembly through the preload disc spring.

5. The bidirectional stepping piezoelectric actuator according to claim 4, characterized in that, The rolling part is a planar bearing, the upper end of which is connected to the lower end of the pressure plate, and the lower end of which is in contact with the upper surface of the motion component.

6. The bidirectional stepping piezoelectric actuator according to claim 5, characterized in that, The preload assembly also includes a flat washer disposed between the head of the preload screw and the preload disc spring.

7. The bidirectional stepping piezoelectric actuator according to claim 1, characterized in that, The piezoelectric ceramic leg also includes a wear-resistant ceramic sheet, and the longitudinal telescopic piezoelectric stack, the transverse shear piezoelectric stack, and the wear-resistant ceramic sheet are bonded together in series by epoxy resin structural adhesive.

8. The bidirectional stepping piezoelectric actuator according to claim 1, characterized in that, The motion component is a motion platform, the support component is a support plate, and the drive component is located between the support plate and the motion platform.

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