A geometer piezoelectric driver

Abstract

The application discloses a inchworm piezoelectric driver, comprising a left clamping unit, a right clamping unit, a pre-tightening unit and a driving unit, the left clamping unit and the right clamping unit are located in the pre-tightening unit, the pre-tightening unit is used for applying a pre-tightening force to the left clamping unit and the right clamping unit, the driving unit is connected with the left clamping unit and the right clamping unit respectively, the left clamping unit, the driving unit and the right clamping unit can move left and right in the pre-tightening unit under time sequence control, the extension and retraction directions of the left clamping unit, the driving unit and the right clamping unit are the same as the movement directions, a larger thrust can be realized in a small volume range, and meanwhile, the piezoelectric driver can provide larger clamping friction to the left clamping unit and the right clamping unit in a power-off state through the pre-tightening unit.

Description

Technical Field

[0001] This application relates to the field of piezoelectric drive technology, and in particular to an inchworm-type piezoelectric actuator. Background Technology

[0002] Inchworm-type piezoelectric actuators are widely used in many fields due to their advantages such as small size, large thrust, high precision, long stroke, fast response and high reliability. They have irreplaceable advantages over other types of piezoelectric actuators.

[0003] However, existing small-volume inchworm-type piezoelectric actuators have low output thrust and power-off retention force, while inchworm-type actuators with high driving force have a large size, which cannot meet the space requirements of small volume. Summary of the Invention

[0004] The purpose of this application is to provide an inchworm-type piezoelectric actuator that can achieve large thrust and large power-off retention force within a small volume.

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

[0006] A inchworm-type piezoelectric actuator includes: a left clamping unit, a right clamping unit, a preload unit, and a drive unit. The left clamping unit and the right clamping unit are located within the preload unit. The preload unit applies a preload force to the left clamping unit and the right clamping unit. The drive unit is connected to the left clamping unit and the right clamping unit respectively. The left clamping unit, the drive unit, and the right clamping unit can move left and right within the preload unit under timing control. The extension and retraction directions of the left clamping unit, the drive unit, and the right clamping unit are the same as their movement directions.

[0007] Preferably, the driving unit includes a driving piezoelectric stack, the pre-tightening unit includes a flexible pre-tightening shell, the left clamping unit includes a left friction block and a plurality of left piezoelectric stacks, and the right clamping unit includes a right friction block and a plurality of right piezoelectric stacks. The left and right friction blocks are located inside the flexible pre-tightening shell, which is used to apply a pre-tightening force to the left and right friction blocks. The driving piezoelectric stack, the left piezoelectric stack, and the right piezoelectric stack can generate elongation motion when powered on, and their elongation direction is the same as the axial direction of the flexible pre-tightening shell.

[0008] Preferably, the drive unit further includes a flexible preload spring and a preload compensation ring. The two ends of the flexible preload spring are respectively connected to the left friction block and the right friction block. The two ends of the drive piezoelectric stack are respectively provided with a preload compensation ring. The preload compensation ring is used to adjust the preload force of the drive piezoelectric stack by adjusting its axial dimension.

[0009] Preferably, the pre-tightening unit further includes a pre-tightening block and a pre-tightening screw. The pre-tightening block is located inside the flexible pre-tightening housing, and the pre-tightening screw is threaded onto the side wall of the flexible pre-tightening housing. The pre-tightening screw is used to control the movement of the pre-tightening block to adjust the pre-tightening force of the pre-tightening unit on the left clamping unit and the right clamping unit.

[0010] Preferably, the flexible pre-tightening housing includes two flexible hinges located on both sides of the pre-tightening block.

[0011] Preferably, the pre-tightening unit further includes a pre-tightening wear-resistant ceramic sheet, the pre-tightening wear-resistant ceramic sheet is provided on the side of the pre-tightening block opposite to the left clamping unit and the right clamping unit, and the pre-tightening wear-resistant ceramic sheet is provided inside the flexible pre-tightening shell on the side opposite to the pre-tightening block.

[0012] Preferably, the outer sides of the left friction block and the right friction block are respectively provided with clamping wear-resistant ceramic sheets corresponding to the pre-tightened wear-resistant ceramic sheets.

[0013] Preferably, the left friction block and the right friction block are both flexible integral friction blocks.

[0014] Compared with existing technologies, the above technical solution has the following advantages:

[0015] The inchworm-type piezoelectric actuator provided in this application includes: a left clamping unit, a right clamping unit, a pre-tightening unit, and a drive unit. The left and right clamping units are located within the pre-tightening unit, which applies a pre-tightening force to the left and right clamping units. The drive unit is connected to the left and right clamping units respectively. The left clamping unit, drive unit, and right clamping unit can move left and right within the pre-tightening unit under timing control. The extension and retraction directions of the left clamping unit, drive unit, and right clamping unit are the same as their movement directions, which can achieve a large thrust within a small volume. At the same time, when the piezoelectric actuator is in a power-off state, the pre-tightening unit can provide a large clamping friction force to the left and right clamping units. Attached Figure Description

[0016] 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.

[0017] Figure 1 A schematic diagram illustrating the structural principle of a inchworm-type piezoelectric actuator provided for a specific embodiment of this application;

[0018] Figure 2 A schematic cross-sectional view of an inchworm-type piezoelectric actuator provided for a specific embodiment of this application;

[0019] Figure 3 A Z-direction cross-sectional view of a inchworm-type piezoelectric actuator provided for a specific embodiment of this application;

[0020] Figure 4 A schematic diagram of the internal structure of a inchworm-type piezoelectric actuator provided for a specific embodiment of this application;

[0021] Figure 5 A schematic diagram of the structure of a flexible preload housing for a inchworm-type piezoelectric actuator provided in a specific embodiment of this application;

[0022] Figure 6 This is a schematic diagram of the structure of the left clamping unit of a inchworm-type piezoelectric actuator provided in a specific embodiment of this application. Detailed Implementation

[0023] 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.

[0024] Please refer to Figures 1-6 , Figure 1 A schematic diagram illustrating the structural principle of a inchworm-type piezoelectric actuator provided for a specific embodiment of this application; Figure 2 A schematic cross-sectional view of an inchworm-type piezoelectric actuator provided for a specific embodiment of this application; Figure 3 A Z-direction cross-sectional view of a inchworm-type piezoelectric actuator provided for a specific embodiment of this application; Figure 4 A schematic diagram of the internal structure of a inchworm-type piezoelectric actuator provided for a specific embodiment of this application; Figure 5 A schematic diagram of the structure of a flexible preload housing for a inchworm-type piezoelectric actuator provided in a specific embodiment of this application; Figure 6 This is a schematic diagram of the structure of the left clamping unit of a inchworm-type piezoelectric actuator provided in a specific embodiment of this application.

[0025] The inchworm-type piezoelectric actuator provided in this application includes: a left clamping unit 1, a right clamping unit 2, a pre-tightening unit 3, and a driving unit 4. The left clamping unit 1 and the right clamping unit 2 are located inside the pre-tightening unit 3. The pre-tightening unit 3 is used to apply a pre-tightening force to the left clamping unit 1 and the right clamping unit 2. The driving unit 3 is connected to the left clamping unit 1 and the right clamping unit 2 respectively. The left clamping unit 1, the driving unit 4, and the right clamping unit 2 can move left and right inside the pre-tightening unit 3 under timing control. The extension and retraction directions of the left clamping unit 1, the driving unit 4, and the right clamping unit 2 are the same as their movement directions. The drive unit 4 includes a drive piezoelectric stack 16; the pre-tightening unit 3 includes a flexible pre-tightening housing 7; the left clamping unit 1 and the right clamping unit 2 each include a friction block 8 and multiple clamping piezoelectric stacks 15, respectively denoted as left friction block, left piezoelectric stack, right friction block, and right piezoelectric stack. For example, two left piezoelectric stacks can be set on both radial sides of the left friction block, and two right piezoelectric stacks can be set on both radial sides of the right friction block. The left and right friction blocks are preferably flexible integral friction blocks, each including four sets of parallel hinges 8a, 8b, 8c, and 8d. The parallel hinges are located on different sides of the corresponding friction blocks from the piezoelectric stacks. The left and right friction blocks are located inside the flexible pre-tightening housing 7, which can apply a pre-tightening force to the left and right friction blocks. The flexible pre-tightening housing 7 has end caps 5 at both ends. It can limit the left clamping unit 1 and the right clamping unit 2; the left clamping unit 1, the right clamping unit 2 and the driving unit 4 are structurally integrated and can move left and right along the axis of the flexible pre-tightening shell 7 under timing control; the driving piezoelectric stack 16, the left piezoelectric stack and the right piezoelectric stack can generate elongation movement when powered on, and their elongation direction is the same as the axial direction of the flexible pre-tightening shell 7, that is, the elongation direction of each piezoelectric stack is the same as the movement direction of the piezoelectric actuator. The maximum output force of the piezoelectric actuator depends on the thrust generated when the piezoelectric stack elongates, and a large thrust can be achieved within a small volume range. At the same time, when the piezoelectric actuator is powered off, the flexible pre-tightening shell 7 can provide a large clamping friction force for the left clamping unit 1 and the right clamping unit 2, which is suitable for application in scenarios with high requirements for size and reliability, such as photolithography projection lenses.

[0026] In some embodiments, such as Figure 4 As shown, the drive unit 4 also includes a flexible preload spring 11 and a preload compensation ring 9. The two ends of the flexible preload spring 11 are connected to the left friction block and the right friction block respectively, for example, by bolts 14. A preload compensation ring 9 is provided at each end of the drive piezoelectric stack 16. The preload compensation ring 9 is used to adjust the preload force of the drive piezoelectric stack 16 by adjusting its axial dimension.

[0027] The operating principle of the inchworm-type piezoelectric actuator is explained below:

[0028] When the inchworm-type piezoelectric actuator moves to the right:

[0029] First, de-energize the left clamping unit 1. At this time, the left clamping unit 1 and the pre-tightening unit 3 maintain their relative positions through static friction.

[0030] When the right clamping unit 2 is powered on, the left piezoelectric stack in the right clamping unit 2 moves back and forth under the action of the control system. At this time, a set of sliding friction forces of equal magnitude and opposite direction are generated between the right clamping unit 2 and the pre-tightening unit 3.

[0031] When the drive unit 4 is powered on, the friction force on the left side of the drive unit 4 is greater than that on the right side. Under the action of the control system, the drive piezoelectric stack in the drive unit 4 drives the right clamping unit 2 to move one step to the right.

[0032] When the right clamping unit 2 is de-energized and the left clamping unit 1 is energized, the left piezoelectric stack in the left clamping unit 1 moves back and forth under the action of the control system. At this time, a set of sliding friction forces of equal magnitude and direction are generated between the left clamping unit 1 and the pre-tightening unit 3.

[0033] When the drive unit 4 is de-energized, the left clamping unit 1 moves one step to the right under the action of the flexible pre-tension spring 11; repeating the above process can realize the continuous stepping motion of the piezoelectric actuator to the right.

[0034] When the inchworm-type piezoelectric actuator moves to the left:

[0035] First, de-energize the right clamping unit 1. At this time, the right clamping unit 2 and the pre-tightening unit 3 maintain their relative positions through static friction.

[0036] When the left clamping unit 1 is powered on, the left piezoelectric stack in the left clamping unit 1 moves back and forth in opposite directions under the action of the control system. At this time, a set of sliding friction forces of equal magnitude and opposite direction are generated between the left clamping unit 1 and the pre-tightening unit 3.

[0037] When the drive unit 4 is powered on, the friction force on the right side of the drive unit 4 is greater than that on the left side. Under the action of the control system, the drive piezoelectric stack in the drive unit 4 drives the left clamping unit 1 to move one step to the left.

[0038] When the left clamping unit 1 is de-energized and the right clamping unit 2 is energized, the right piezoelectric stack in the right clamping unit 2 moves back and forth under the action of the control system. At this time, a set of sliding friction forces of equal magnitude and direction are generated between the right clamping unit 1 and the pre-tightening unit 3.

[0039] When the drive unit 4 is de-energized, the right clamping unit 2 moves one step to the left under the action of the flexible pre-tension spring 11; repeating the above process can realize the continuous stepping motion of the piezoelectric actuator to the left.

[0040] In the static state of a inchworm-type piezoelectric actuator, under a preload F NUnder the action of the clamping unit, a frictional force f will be generated on the contact surface between the clamping unit and the outer shell. The frictional forces generated on the left and right sides of the drive unit are f1 and f2, respectively. L =f R =f max =0.5μF N

[0041] Among them, f L f is the static friction force acting on the left clamping unit 1. R Let μ be the static friction force acting on the right clamping unit 2, and μ be the coefficient of friction; then the power-off holding force of the inchworm-type piezoelectric actuator is F. hold =f L +f R =2f max

[0042] When the inchworm-type piezoelectric actuator moves, the maximum output force F it can generate is... max =F P ,F P This is the thrust that drive unit 4 can generate.

[0043] In some embodiments, such as Figure 5 As shown, the pre-tightening unit 3 also includes a pre-tightening block 6 and a pre-tightening screw 10. The pre-tightening block 6 is located inside the flexible pre-tightening housing 7, and the pre-tightening screw 10 is threaded onto the side wall of the flexible pre-tightening housing 7. For example, a groove for placing the pre-tightening block 6 can be provided in the inner top of the flexible pre-tightening housing 7, and the pre-tightening screw 10 is connected to the top of the flexible pre-tightening housing 7. The inner top and inner bottom of the flexible pre-tightening housing 7 are preferably flat, and correspondingly, the upper and lower surfaces of the left and right friction blocks are also flat. The structure of the pre-tightening block 6 is preferably a plate-like structure extending along the axial direction of the flexible pre-tightening housing 7, and the number of pre-tightening screws 10 is preferably multiple. By turning the pre-tightening screw 10, the movement of the pre-tightening block 6 can be controlled to adjust the pre-tightening force of the pre-tightening unit 3 on the left and right clamping units. The flexible pre-tightening housing 7 includes two flexible hinges 7a and 7b located on both sides of the pre-tightening block 6. Under the action of the adjusting pre-tightening screw 10, the flexible hinges deform, thereby generating positive pressure in the Z-direction, and generating friction between the left clamping unit 1, the right clamping unit 2 and the pre-tightening unit 3.

[0044] Furthermore, such as Figure 6As shown, the pre-tightening unit 3 also includes a pre-tightening wear-resistant ceramic sheet 12. The pre-tightening pressure block 6 has a pre-tightening wear-resistant ceramic sheet 12 on its side opposite to the left clamping unit 1 and the right clamping unit 2. The flexible pre-tightening housing 7 also has a pre-tightening wear-resistant ceramic sheet 12 on its side opposite to the pre-tightening pressure block 6. The pre-tightening wear-resistant ceramic sheet 12 can be fixed by adhesive bonding. The outer sides of the left and right friction blocks are respectively provided with clamping wear-resistant ceramic sheets 13 corresponding to the pre-tightening wear-resistant ceramic sheet 12, which can also be fixed by adhesive bonding. The pre-tightening wear-resistant ceramic sheet 12 and the clamping wear-resistant ceramic sheet 13 can reduce wear between the left friction block, the right friction block, and the flexible pre-tightening housing 7.

[0045] 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.

[0046] The foregoing has provided a detailed description of the inchworm-type 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 the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. A inchworm-type piezoelectric actuator, characterized in that, include: The system comprises a left clamping unit, a right clamping unit, a pre-tightening unit, and a drive unit. The left clamping unit and the right clamping unit are located within the pre-tightening unit. The pre-tightening unit applies a pre-tightening force to the left clamping unit and the right clamping unit. The drive unit is connected to the left clamping unit and the right clamping unit respectively. Under timing control, the left clamping unit, the drive unit, and the right clamping unit can move left and right within the pre-tightening unit. The extension and retraction directions of the left clamping unit, the drive unit, and the right clamping unit are the same as their movement directions. The driving unit includes a driving piezoelectric stack, the pre-tightening unit includes a flexible pre-tightening shell, the left clamping unit includes a left friction block and multiple left piezoelectric stacks, and the right clamping unit includes a right friction block and multiple right piezoelectric stacks. The left and right friction blocks are located inside the flexible pre-tightening shell, which applies a pre-tightening force to the left and right friction blocks. The driving piezoelectric stack, the left piezoelectric stack, and the right piezoelectric stack can elongate in the energized state, and their elongation direction is the same as the axial direction of the flexible pre-tightening shell. The drive unit further includes a flexible preload spring and a preload compensation ring. The two ends of the flexible preload spring are respectively connected to the left friction block and the right friction block. The two ends of the drive piezoelectric stack are respectively provided with a preload compensation ring. The preload compensation ring is used to adjust the preload force of the drive piezoelectric stack by adjusting its axial dimension. The pre-tightening unit further includes a pre-tightening block and a pre-tightening screw. The pre-tightening block is located inside the flexible pre-tightening housing, and the pre-tightening screw is threaded onto the side wall of the flexible pre-tightening housing. The pre-tightening screw is used to control the movement of the pre-tightening block to adjust the pre-tightening force of the pre-tightening unit on the left clamping unit and the right clamping unit.

2. The inchworm-type piezoelectric actuator according to claim 1, characterized in that, The flexible pre-tightening housing includes two flexible hinges located on both sides of the pre-tightening block.

3. The inchworm-type piezoelectric actuator according to claim 1, characterized in that, The pre-tightening unit further includes a pre-tightening wear-resistant ceramic sheet. The pre-tightening wear-resistant ceramic sheet is provided on the side of the pre-tightening block opposite to the left clamping unit and the right clamping unit. The pre-tightening wear-resistant ceramic sheet is also provided on the side of the flexible pre-tightening shell opposite to the pre-tightening block.

4. The inchworm-type piezoelectric actuator according to claim 3, characterized in that, The outer sides of the left friction block and the right friction block are respectively provided with clamping wear-resistant ceramic plates corresponding to the pre-tightened wear-resistant ceramic plates.

5. The inchworm-type piezoelectric actuator according to claim 1, characterized in that, The left friction block and the right friction block are both flexible integral friction blocks.

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