A parasitic inertial piezoelectric actuator for achieving low frequency and high speed

Abstract

The present invention relates to a parasitic inertia type piezoelectric actuator for realizing low-frequency high-speed movement, which solves the technical problem that the parasitic inertia type piezoelectric actuator cannot achieve high-speed movement when driven by low-frequency signals. The actuator mainly includes a piezoelectric stack, a secondary lever flexible hinge mechanism, and a moving guide rail. Two piezoelectric stacks are simultaneously energized and driven, and the displacement is doubled through the secondary lever and the Z-shaped beam in the secondary lever flexible hinge mechanism, increasing the unit step length of the actuator, and thus greatly increasing the unit speed to achieve the goal of low-frequency high-speed movement; the secondary lever flexible hinge mechanism has high stiffness and can bear a large load, and the stiffness in the main output direction of the piezoelectric stack is also fully utilized, improving the output load of the actuator. The actuator has a simple structure and can be applied to fields such as micro-operation robots.

Description

Technical Field

[0001] The present invention relates to the fields of precision and ultra-precision machining, micro-nano operation robots, and micro-electromechanical systems. In particular, it relates to a parasitic inertia type piezoelectric actuator for achieving low frequency and high speed. Background Art

[0002] As a new type of precision drive method, piezoelectric drive technology has been widely used in the fields of aerospace, semiconductor manufacturing, micro-nano machining, and medical science due to its multiple outstanding advantages such as high precision, fast response, no electromagnetic interference, and good controllability, and many achievements have been made.

[0003] Piezoelectric actuators can be roughly divided into four types according to their working principles: direct drive type, ultrasonic type, bionic type, and stick-slip type. Among them, the stick-slip type piezoelectric actuator can be divided into parasitic inertia type and constant force contact type according to whether the contact force changes. Piezoelectric ultrasonic actuators often couple the phases of excitation signals and use the resonance of piezoelectric elements to excite the stator to generate an elliptical trajectory, thereby driving the mover to perform linear or rotational motion, and have advantages such as large output force and high speed. Since the piezoelectric ultrasonic actuator itself works under resonance conditions and uses the friction force between the stator and the mover as the driving force, the problems of severe wear and heat generation are difficult to solve. The direct drive type piezoelectric actuator usually uses a piezoelectric stack or combines a flexible displacement amplification mechanism to directly act on the mover. It has a large output force and high positioning accuracy. However, due to the limitation of the elongation of the piezoelectric stack, the stroke of the direct drive type piezoelectric actuator is usually only a dozen micrometers, which limits its practical application in the fields of micro-nano manufacturing and precision drive. The bionic type piezoelectric actuator, taking the inchworm type as an example, is based on the motion bionics design of the inchworm. Usually, three or more piezoelectric elements are designed collaboratively and have a large driving force, but it also correspondingly complicates the structure of the positioning platform and the control is more complex. Compared with other types of piezoelectric actuators, the parasitic inertia type actuator has the greatest advantage in realizing a compact micro-motion device due to its simple structure, high speed, low cost, theoretically infinite stroke displacement, and the possibility of batch manufacturing. However, currently, the piezoelectric actuator designed based on the parasitic inertia principle usually increases the speed by increasing the driving frequency, which will cause heat generation and wear of the actuator itself, limiting its further development and application in related fields. Summary of the Invention

[0004] The purpose of the present invention is to provide a parasitic inertia type piezoelectric actuator for achieving low frequency and high speed, so as to solve the technical problem that the existing parasitic inertia type piezoelectric actuator cannot achieve high-speed motion under the drive of low-frequency signals. The structure of the present invention is simple and compact, and it can achieve high-speed output under the drive of low-frequency signals.

[0005] To achieve the above object, the present invention provides a parasitic inertial piezoelectric actuator for realizing low frequency and high speed, mainly including a positioning hole 1, a single-degree-of-freedom displacement platform 2, a pre-tightening block I 3, a piezoelectric stack I 4, a moving guide rail 7, a fixed guide rail 8, a fixing screw 12, a piezoelectric stack II 14, a pre-tightening block II 15, a two-stage lever flexible hinge mechanism 16, a metal connecting plate 17, a metal base 18, and a pre-tightening knob 19. The two-stage lever flexible hinge mechanism 16 is composed of a first-stage lever mechanism I 5, a first-stage lever mechanism II 13, a second-stage lever mechanism I 6, a second-stage lever mechanism II 11, a driving foot 9, a Z-shaped beam 10, a right-angle flexible hinge, and a fixed base. The first-stage lever mechanism I 5, the first-stage lever mechanism II 13, the second-stage lever mechanism I 6, and the second-stage lever mechanism II 11 are arranged in parallel and form an angle of 120° with the movement direction of the moving guide rail. The first-stage lever mechanism I 5 and the first-stage lever mechanism II 13 have the same structure, and the second-stage lever mechanism I 6 and the second-stage lever mechanism II 11 have the same structure. The first-stage lever mechanism I 5 is on the right side of the second-stage lever mechanism I 6, and the first-stage lever mechanism II 13 is on the right side of the second-stage lever mechanism II 11. The first-stage lever mechanism I 5 and the first-stage lever mechanism II 13 are respectively connected to the second-stage lever mechanism I 6 and the second-stage lever mechanism II 11 through right-angle flexible hinges to form a two-stage lever mechanism, and the Z-shaped beam 10 connects the second-stage lever mechanism I 6 and the second-stage lever mechanism II 11 to form a whole. The Z-shaped beam 10 is provided with a driving foot 9, which can drive the moving guide rail 7 to perform linear motion. Among them, the two-stage lever mechanism, the right-angle flexible hinge, and the Z-shaped beam 10 all have good deformation effects, and generate deformation and accumulate layer by layer under the drive of the piezoelectric stack to drive the moving guide rail to move. The piezoelectric stack I 4 and the piezoelectric stack II 14 are located inside the two-stage lever flexible hinge mechanism 16 and are respectively in contact with the first-stage lever mechanism I 5 and the first-stage lever mechanism II 13. The main output directions of the piezoelectric stack I 4 and the piezoelectric stack II 14 form an angle of 30° with the movement direction of the moving guide rail. The moving guide rail 7 adopts a high-precision linear guide rail with a slider. The fixed guide rail 8 is fixed on the metal base 18 by screws to achieve high-precision linear motion. The two-stage lever flexible hinge mechanism 16 is installed on the metal connecting plate 17 by screws, and the metal connecting plate 17 is installed on the metal base 18 by screws. The piezoelectric stack I 4 and the piezoelectric stack II 14 can be pre-tightened respectively through the pre-tightening block I 3 and the pre-tightening block II 15. The positioning hole 1 can roughly adjust the relative position between the two-stage lever flexible hinge mechanism 16 and the moving guide rail 7, and the pre-tightening knob 19 can finely adjust the initial pre-tightening force between the two-stage lever flexible hinge mechanism 16 and the moving guide rail 7.

[0006] The advantages of the present invention are as follows: The first-stage lever mechanism I5 and the first-stage lever mechanism II13 are respectively connected to the second-stage lever mechanism I6 and the second-stage lever mechanism II11 through right-angle flexible hinges to form a two-stage lever mechanism. The Z-shaped beam 10 connects the second-stage lever mechanism I6 and the second-stage lever mechanism II11 to form a whole. The Z-shaped beam 10 is provided with a driving foot 9, which can drive the moving guide rail 7 to perform a linear motion. Among them, the two-stage lever mechanism, the right-angle flexible hinge, and the Z-shaped beam all have good deformation effects. Under the simultaneous drive of the piezoelectric stack I4 and the piezoelectric stack II14, large deformations are generated and accumulated layer by layer, having a good displacement amplification effect. Finally, the moving guide rail 7 is driven to generate a large single-step displacement, thereby greatly increasing the driving speed. The two-stage lever flexible hinge mechanism has a high stiffness and can bear a large load. The main output directions of the piezoelectric stack I4 and the piezoelectric stack II14 form an angle of 30° with the moving direction of the moving guide rail, and the pre-tightening blocks I3 and pre-tightening blocks II15 are used for pre-tightening and positioning. Such an arrangement fully utilizes the relatively high stiffness in the main output direction of the piezoelectric stack, can cause parasitic motion of the driving foot, and improves the load performance and motion stability of the entire device. It can be applied to important scientific engineering fields such as precision and ultra-precision machining, micro-operation robots, micro-electromechanical systems, large-scale integrated circuit manufacturing, and biotechnology. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is a schematic diagram of the overall structure of the present invention;

[0008] Figure 2 is the front view of the present invention;

[0009] Figure 3 is the left view schematic diagram of the present invention;

[0010] Figure 4 is the two-stage lever flexible hinge mechanism of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] The following further describes in detail the embodiments of the present invention in conjunction with the drawings and embodiments.

[0012] A parasitic inertial type piezoelectric actuator for realizing low frequency and high speed mainly includes a positioning hole 1, a single-degree-of-freedom displacement platform 2, a pre-tightening block I 3, a piezoelectric stack I 4, a moving guide rail 7, a fixed guide rail 8, a fixing screw 12, a piezoelectric stack II 14, a pre-tightening block II 15, a two-stage lever flexible hinge mechanism 16, a metal connecting plate 17, a metal base 18, and a pre-tightening knob 19. The two-stage lever flexible hinge mechanism 16 has a good displacement amplification effect. The two-stage lever flexible hinge mechanism 16 is composed of a first-stage lever mechanism I 5, a first-stage lever mechanism II 13, a second-stage lever mechanism I 6, a second-stage lever mechanism II 11, a driving foot 9, a Z-shaped beam 10, a right-angle flexible hinge, and a fixed base. The first-stage lever mechanism I 5, the first-stage lever mechanism II 13, the second-stage lever mechanism I 6, and the second-stage lever mechanism II 11 are arranged in parallel and form an angle of 120° with the moving direction of the moving guide rail. The first-stage lever mechanism I 5 and the first-stage lever mechanism II 13 have the same structure, and the second-stage lever mechanism I 6 and the second-stage lever mechanism II 11 have the same structure. The first-stage lever mechanism I 5 is on the right side of the second-stage lever mechanism I 6, and the first-stage lever mechanism II 13 is on the right side of the second-stage lever mechanism II 11. The first-stage lever mechanism I 5 and the first-stage lever mechanism II 13 are respectively connected to the second-stage lever mechanism I 6 and the second-stage lever mechanism II 11 through right-angle flexible hinges to form a two-stage lever mechanism, and the Z-shaped beam 10 connects the second-stage lever mechanism I 6 and the second-stage lever mechanism II 11 to form an integral body. The Z-shaped beam 10 is provided with a driving foot 9, which can drive the moving guide rail 7 to perform a linear motion. Among them, the two-stage lever mechanism, the right-angle flexible hinge, and the Z-shaped beam all have good deformation effects, generate large deformations under the drive of the piezoelectric stack and accumulate layer by layer, and finally drive the moving guide rail to generate a large single-step displacement, thereby greatly increasing the driving speed. The moving guide rail 7 adopts a high-precision linear guide rail with sliders. The fixed guide rail 8 is fixed on the metal base 18 by screws to realize high-precision linear motion. The two-stage lever flexible hinge mechanism 16 is installed on the metal connecting plate 17 by screws, and the metal connecting plate 17 is installed on the metal base 18 by screws. The piezoelectric stack I 4 and the piezoelectric stack II 14 can be pre-tightened by the pre-tightening block I 3 and the pre-tightening block II 15 respectively. The positioning hole 1 can roughly adjust the relative position between the two-stage lever flexible hinge mechanism 16 and the moving guide rail 7, and the pre-tightening knob 19 can finely adjust the initial pre-tightening force between the two-stage lever flexible hinge mechanism 16 and the moving guide rail 7.

[0013] The described parasitic inertia type piezoelectric actuator for realizing low frequency and high speed utilizes the parasitic inertia principle to achieve precise piezoelectric linear drive. The piezoelectric stack I4 and the piezoelectric stack II14 are located inside the secondary lever flexible hinge mechanism 16 and are respectively in contact with the primary lever mechanism I5 and the primary lever mechanism II13. The included angle between the main output directions of the piezoelectric stack I4 and the piezoelectric stack II14 and the moving direction of the moving guide rail is 30°. The greater stiffness in the main output directions of the piezoelectric stack I4 and the piezoelectric stack II14 is fully utilized. The secondary lever flexible hinge mechanism 16 generates a large deformation amount under the simultaneous drive of the two piezoelectric stacks to drive the moving guide rail 7 and realize parasitic inertia motion. This motion mode of increasing the unit step can greatly increase the speed of the moving guide rail 7 within the motion period, improve the output performance of the actuator, and realize the linear motion of the moving guide rail 7 along a certain direction.

[0014] By simultaneously adjusting the voltages and frequencies of the two piezoelectric stacks, the lengths of the two piezoelectric stacks are caused to change. Since the secondary lever flexible hinge mechanism 16 amplifies the length change of the piezoelectric stack, the driving foot can drive the moving guide rail to generate a unit step far exceeding the elongation of the piezoelectric stack.

[0015] The specific working process of the present invention is as follows:

[0016] Realization of the linear motion of the moving guide rail 7, initial state: Coarsely position the secondary lever flexure hinge mechanism 16 to a suitable position from the moving guide rail 7 by selecting the positioning hole 1, and adjust the pre-tightening knob 19 to finely adjust the contact distance between the secondary lever flexure hinge mechanism 16 and the moving guide rail 7, that is, the initial pre-tightening force during the parasitic motion process; Control the piezoelectric stack I 4 and the piezoelectric stack II 14 simultaneously with an electrical signal in the form of a sawtooth wave or a triangular wave. The piezoelectric stack I 4 and the piezoelectric stack II 14 are not charged, and the system is in a free state, that is, neither of the two piezoelectric stacks elongates, and the secondary lever flexure hinge mechanism 16 does not deform; When the piezoelectric stack I 4 and the piezoelectric stack II 14 are energized simultaneously, due to the inverse piezoelectric effect, the piezoelectric stack I 4 and the piezoelectric stack II 14 elongate, pushing the secondary lever flexure hinge mechanism 16 to deform. Specifically, during the deformation process, after the piezoelectric stack I 4 and the piezoelectric stack II 14 elongate, the first-level lever mechanism I 5 and the first-level lever mechanism II 13 inside the secondary lever flexure hinge mechanism 16 deform, and the force and displacement are respectively transmitted and accumulated to the second-level lever mechanism I 6 and the second-level lever mechanism II 11 by the right-angle flexure hinge. The force and displacement of the two secondary levers are integrated by the Z-shaped beam 10 and drive the moving guide rail 7 to perform linear motion in a certain direction through the driving foot 9 thereon. Among them, the lever mechanism, the right-angle flexure hinge, and the Z-shaped beam all have good deformation effects, and large deformations are generated and accumulated layer by layer under the drive of the piezoelectric stack I 4 and the piezoelectric stack II 14, and finally drive the moving guide rail 7 to generate a large single-step displacement, thereby greatly increasing the driving speed; When the piezoelectric stack I 4 and the piezoelectric stack II 14 lose power and shorten, the deformation of the secondary lever flexure hinge mechanism 16 disappears, and the driving foot 9 will move in the reverse direction. However, due to inertia, the displacement of the backward movement is much smaller than that of the forward movement. Therefore, a relatively large step length will be accumulated within a unit cycle. Thus, the described parasitic inertia type piezoelectric actuator for realizing low frequency and high speed has completed a motion cycle. Repeat the above steps, and this actuator can realize low-frequency and high-speed linear motion in the required direction.

Claims

1. A parasitic inertia type piezoelectric actuator for realizing low frequency and high speed, mainly comprising a positioning hole (1), a single degree of freedom displacement platform (2), a preloading block I (3), a piezoelectric stack I (4), a moving guide rail (7), a fixed guide rail (8), a fixing screw (12), a piezoelectric stack II (14), a preloading block II (15), a two-stage lever flexible hinge mechanism (16), a metal connecting plate (17), a metal base (18), and a preloading knob (19), characterized in that: The secondary lever flexible hinge mechanism (16) consists of a first-stage lever mechanism I (5), a first-stage lever mechanism II (13), a second-stage lever mechanism I (6), a second-stage lever mechanism II (11), a driving foot (9), a Z-shaped beam (10), right-angle flexible hinges, and a fixed base. Among them, the first-stage lever mechanism I (5), the first-stage lever mechanism II (13), the second-stage lever mechanism I (6), and the second-stage lever mechanism II (11) are arranged in parallel, and the angle with the moving direction of the moving guide rail is 120°. The first-stage lever mechanism I (5) and the first-stage lever mechanism II (13) have the same structure, and the second-stage lever mechanism I (6) and the second-stage lever mechanism II (11) have the same structure. The first-stage lever mechanism I (5) is on the right side of the second-stage lever mechanism I (6), and the first-stage lever mechanism II (13) is on the right side of the second-stage lever mechanism II (11). The first-stage lever mechanism and the second-stage lever mechanism, the fixed screw mounting platform and the first-stage lever mechanism, the first-stage lever mechanism and the piezoelectric stack mounting platform, and the second-stage lever mechanism and the fixed base are all connected by right-angle flexible hinges; the cross beam connecting the second-stage lever mechanism I (6) and the second-stage lever mechanism II (11) is a Z-shaped beam and forms an integral body with the second-stage lever mechanism. The Z-shaped beam (10) is provided with a driving foot (9), and the width of the cross bar of the Z-shaped beam is smaller than the width of the second-stage lever mechanism; the piezoelectric stack I (4) and the piezoelectric stack II (14) are located inside the secondary lever flexible hinge mechanism (16) and are respectively in contact with the first-stage lever mechanism I (5) and the first-stage lever mechanism II (13). The main output directions of the piezoelectric stack I (4) and the piezoelectric stack II (14) form an angle of 30° with the moving direction of the moving guide rail; the secondary lever mechanism, the right-angle flexible hinges, and the Z-shaped beam (10) are deformed and accumulated layer by layer under the drive of the piezoelectric stack to drive the movement of the moving guide rail.

2. The parasitic inertia type piezoelectric actuator for realizing low frequency and high speed according to claim 1, wherein: The moving guide rail (7) uses a high-precision linear guide rail with sliders. The fixed guide rail (8) is fixed to the metal base (18) by screws to achieve high-precision linear motion. The secondary lever flexible hinge mechanism (16) is installed on the metal connecting plate (17) by screws, and the metal connecting plate (17) is installed on the metal base (18) by screws. The piezoelectric stack I (4) and the piezoelectric stack II (14) can be pre-tightened by the pre-tightening block I (3) and the pre-tightening block II (15) respectively. The positioning hole (1) can roughly adjust the relative position between the secondary lever flexible hinge mechanism (16) and the moving guide rail (7), and the pre-tightening knob (19) can adjust the initial pre-tightening force between the secondary lever flexible hinge mechanism (16) and the moving guide rail (7).

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