A stick-slip piezoelectric driver with two-stage amplification mechanism and a driving method thereof

Abstract

The present invention relates to a stick-slip piezoelectric driver with a two-stage amplification mechanism and a driving method thereof, and belongs to the field of precision machinery. The driver includes a base, a slider, a two-stage amplification mechanism, a piezoelectric stack, a wedge block and a pre-tightening mechanism. The two-stage amplification mechanism is composed of a first-stage flexible amplification mechanism and a second-stage flexible amplification mechanism of similar structure and opposite direction connected in series. The deformation generated by the piezoelectric stack after being energized is amplified twice by the two-stage amplification mechanism, and is converted into a positive x-direction displacement of the driving foot, and the directional drive of the slider is realized by friction. The advantage of the present invention is that the output efficiency of the stick-slip piezoelectric driver can be effectively improved by the new two-stage amplification mechanism, and high-speed driving under low-frequency conditions can be realized. The present invention can be used in the fields of precision machining, optical instruments, bioengineering, aerospace technology, etc.

Description

Technical Field

[0001] The present invention relates to a stick-slip piezoelectric driver with a two-stage amplification mechanism and a driving method thereof, and belongs to the field of precision machinery. The present invention solves the problem that the stick-slip piezoelectric driver has a relatively low driving speed under low-frequency conditions. The present invention can be used in the fields of integrated circuit packaging, optical focusing, micro / nanomechanical testing, and micro-nano operation. Background Art

[0002] As one of the precision driving technologies, piezoelectric driving technology has attracted the attention of researchers for its advantages such as high precision, small size, low energy consumption, high energy density and no electromagnetic interference. It is widely used in high-end fields such as integrated circuit packaging, micro-nano operation, ultra-precision machining and biomedicine.

[0003] In existing studies, researchers have proposed piezoelectric actuators based on different working principles, which can be roughly divided into four categories: direct-acting piezoelectric actuators have the advantages of high output accuracy, simple structure and rapid response. However, their working stroke is small and cannot meet the needs of large-stroke working occasions; ultrasonic piezoelectric actuators theoretically have unlimited working strokes, but their positioning accuracy is low, and high operating frequencies often cause serious wear and tear, resulting in a shortened service life; inchworm-type piezoelectric actuators have complex structures and are difficult to control, which also limits their development; stick-slip piezoelectric actuators have the advantages of large stroke, high accuracy, simple structure and easy control, but their driving speed is relatively low.

[0004] It is easiest to effectively optimize the working state of the piezoelectric driver and improve the stick-slip driving speed. Commonly used speed-up methods are: increasing the driving frequency and using a displacement amplification mechanism. However, for stick-slip piezoelectric drivers, a high-frequency working environment will also bring about problems such as severe wear and unstable working state, which not only shortens the service life, but also makes it difficult to achieve ideal positioning accuracy. The existing displacement amplification mechanism has a limited amplification ratio, especially after being loaded, the amplification ratio often drops sharply, making it difficult to meet the needs of large step distances. Therefore, the present invention proposes a displacement amplification mechanism that can significantly increase the step distance-a two-stage amplification mechanism, which solves the problem of relatively low output speed of stick-slip piezoelectric drivers. The present invention achieves high-speed movement of stick-slip piezoelectric drivers under low-frequency conditions through a two-stage amplification mechanism. Summary of the invention

[0005] In order to solve the problem of low speed of the existing stick-slip piezoelectric driver under low frequency conditions, the present invention proposes a stick-slip piezoelectric driver with a two-stage amplification mechanism.

[0006] The technical solution adopted by the present invention to achieve the above-mentioned purpose is as follows:

[0007] A stick-slip piezoelectric driver with a two-stage amplification mechanism, characterized in that: through the application of the two-stage amplification mechanism, only one piezoelectric stack can be used to achieve two output displacement amplifications; the driver includes a base, a slider, a two-stage amplification mechanism, a piezoelectric stack, a wedge block and a preload mechanism; the two-stage amplification mechanism consists of a fixed beam, a first-stage flexible amplification mechanism, a support beam, a second-stage flexible amplification mechanism and a driving foot, which are arranged in series along the positive y direction; the slider is installed at one end of the base boss, and the preload mechanism for adjusting the preload force between the slider and the driving foot is fixedly installed at the other end of the base; the piezoelectric stack is preloaded and embedded in the first-stage flexible amplification mechanism through the wedge block and directly acts on the support beam; under the control of a sawtooth electrical signal, the piezoelectric stack periodically slowly extends and quickly contracts, and realizes the linear motion of the slider along the positive x direction according to the stick-slip motion principle.

[0008] The first-stage flexible amplification mechanism is a parallelogram guiding mechanism formed by two leaf-type flexible hinges I connected in parallel, which are at an obtuse angle to the positive x-direction. When the piezoelectric stack is electrically stretched by Δy1, the first-stage flexible amplification mechanism is deformed by the tensile effect. Based on the principle of parasitic motion, the support beam, the second-stage flexible amplification mechanism and the driving foot as a whole produce a positive y-direction displacement Δy1, accompanied by a positive x-direction displacement Δx1.

[0009] The second-stage flexible amplification mechanism is a parallelogram guiding mechanism formed by two leaf-type flexible hinges II connected in parallel, which are at an acute angle to the positive x-direction. When the piezoelectric stack is electrically stretched by Δy1, the second-stage flexible amplification mechanism is deformed by compression, and the driving foot will also produce a positive x-direction displacement Δx2.

[0010] Another object of the present invention is to provide a driving method of a stick-slip piezoelectric actuator having a two-stage amplification mechanism, comprising the following steps:

[0011] ① The piezoelectric stack and the wedge block are embedded in the first-stage flexible amplification mechanism in a tight fit; the two-stage amplification mechanism is installed on the preload mechanism by screws, and the preload mechanism knob is adjusted to achieve elastic contact between the slider and the driving foot;

[0012] ② Input a sawtooth-shaped electrical signal to the piezoelectric stack. Based on the inverse piezoelectric effect, the piezoelectric stack slowly stretches when it is electrified. Under the superposition of the displacement amplification of the first-stage flexible amplification mechanism and the second-stage flexible amplification mechanism, it is converted into the displacement of the driving foot along the positive x-direction, and then the slider is pushed to move x1 along the positive x-direction through friction. Subsequently, the piezoelectric stack loses power and shrinks rapidly, the two-stage amplification mechanism returns to the initial state, and the slider retreats slightly x2 along the negative x-direction. Repeating the above two stages can achieve stable stepping.

[0013] ③ By adjusting the voltage amplitude and driving frequency of the piezoelectric stack input electrical signal, the movement state of the slider can be changed.

[0014] The beneficial effects of the present invention are as follows: a stick-slip piezoelectric driver with a two-stage amplification mechanism can effectively amplify the single-step pitch, realize high-speed driving under low-frequency conditions, and significantly improve the output efficiency of the stick-slip piezoelectric driver. At the same time, the stick-slip piezoelectric driver has the advantages of simple structure, easy control and high resolution. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings described herein are used to provide further understanding of the present invention and constitute a part of this application. The illustrative examples of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0016] Figure 1 It is a structural schematic diagram of the present invention.

[0017] Figure 2 It is a top view schematic diagram of the two-stage amplification mechanism of the present invention.

[0018] Figure 3 It is a schematic diagram of the two-stage amplification principle of the present invention.

[0019] Figure 4 It is a schematic diagram of the working process of the present invention.

[0020] Figure 5 The invention is a curve showing the relationship between the actual output speed v and the driving frequency f measured under the driving voltage U=100V and the locking force F=2N.

[0021] In the figure: 1. base; 2. slider; 3. two-stage amplification mechanism; 3.1. fixed beam; 3.2. first-stage flexible amplification mechanism; 3.2.1. leaf-type flexible hinge I; 3.3. support beam; 3.4. second-stage flexible amplification mechanism; 3.4.1. leaf-type flexible hinge II; 3.5. driving foot; 4. piezoelectric stack; 5. wedge block; 6. preload mechanism. DETAILED DESCRIPTION

[0022] The details of the present invention and its specific implementation methods will be further described below in conjunction with the accompanying drawings.

[0023] See also Figures 1 to 5 As shown, the present invention proposes a stick-slip piezoelectric driver with a two-stage amplification mechanism and a driving method thereof, designs a new displacement amplification mechanism, improves the single-step pitch of the stick-slip piezoelectric driver, and is of great significance for achieving high-speed driving under low-frequency conditions.

[0024] The stick-slip piezoelectric driver with a two-stage amplification mechanism is characterized in that the driver comprises a base (1), a slider (2), a two-stage amplification mechanism (3), a piezoelectric stack (4), a wedge block (5) and a preload mechanism (6). The driver optimizes the problem of low output speed of the stick-slip piezoelectric driver by applying the two-stage amplification mechanism (3), while retaining the advantages of the stick-slip piezoelectric driver such as easy control, simple structure and high resolution, thereby enhancing its application in the fields of precision machining, integrated circuit packaging, micro-nano operation, space technology, etc.

[0025] See also Figure 1 , Figure 2 As shown, a stick-slip piezoelectric actuator with a two-stage amplification mechanism of the present invention comprises a base (1), a slider (2), a two-stage amplification mechanism (3), a piezoelectric stack (4), a wedge block (5) and a preload mechanism (6); the two-stage amplification mechanism (3) is composed of a fixed beam (3.1), a first-stage flexible amplification mechanism (3.2), a support beam (3.3), a second-stage flexible amplification mechanism (3.4) and a driving foot (3.5) which are arranged in series in sequence along the positive y direction; the slider (2) is installed on At one end of the boss of the base (1), a preload mechanism (6) for adjusting the preload force between the slider (2) and the driving foot (3.5) is fixedly installed at the other end of the base (1); the piezoelectric stack (4) is preloaded and embedded into the first-stage flexible amplification mechanism (3.2) through a wedge block (5) and directly acts on the support beam (3.3); under the control of a sawtooth electrical signal, the piezoelectric stack (4) periodically slowly extends and quickly contracts, and realizes the linear motion of the slider (2) along the positive x-direction according to the stick-slip motion principle.

[0026] The first-stage flexible amplification mechanism (3.2) is a parallelogram guide mechanism formed by two leaf-type flexible hinges I (3.2.1) connected in parallel, which have an obtuse angle with the positive x-direction. When the piezoelectric stack (4) is energized and stretched by Δy1, the first-stage flexible amplification mechanism (3.2) is deformed by the tensile effect. Based on the principle of parasitic motion, the support beam (3.3), the second-stage flexible amplification mechanism (3.4) and the driving foot (3.5) as a whole generate a positive y-direction displacement Δy1, and an accompanying positive x-direction displacement Δx1.

[0027] The second-stage flexible amplification mechanism (3.4) is a parallelogram guide mechanism formed by two leaf-type flexible hinges II (3.4.1) connected in parallel, which are acutely angled with the positive x-direction. When the piezoelectric stack (4) is electrically stretched by Δy1, the second-stage flexible amplification mechanism (3.4) is deformed by compression, and the driving foot (5) also generates a positive x-direction displacement Δx2.

[0028] See also Figure 3As shown, a schematic diagram of the two-stage amplification principle of the present invention is shown. When the first-stage flexible amplification mechanism (3.2) works alone, the piezoelectric stack (4) is electrically extended and directly acts on the support beam (3.3). The first-stage flexible amplification mechanism (3.2) is stretched and deformed. Based on the principle of parasitic motion, the support beam (3.3), the second-stage flexible amplification mechanism (3.4) and the driving foot (3.5) generate a positive y-direction displacement Δy1 and a positive x-direction displacement Δx1. When the second-stage flexible amplification mechanism (3.4) works alone, it is compressed and deformed by the piezoelectric stack (4), which also causes the driving foot (3.5) to generate a positive x-direction displacement Δx2. Because both the first-stage flexible amplification mechanism (3.2) and the second-stage flexible amplification mechanism (3.4) can move the driving foot (3.5) along the positive x-direction under the action of the extended piezoelectric stack (4). The present invention connects the two in series, and uses the output of the first-stage flexible amplification mechanism (3.2) as the input of the second-stage flexible amplification mechanism (3.4), so that the elongation of the piezoelectric stack (4) can be amplified twice. Theoretically, this configuration can effectively amplify the single-step pitch of the stick-slip piezoelectric driver, and has a significant effect on increasing the output speed under low-frequency conditions.

[0029] See also Figure 3 and Figure 4 As shown, the working process of a stick-slip piezoelectric actuator with a two-stage amplification mechanism of the present invention includes the following steps:

[0030] ① At time t0, the piezoelectric stack (4) and the wedge block (5) are embedded in the first-stage flexible amplification mechanism (3.2) in a tight fit; the two-stage amplification mechanism (3) is mounted on the pre-tightening mechanism (6) by means of screws, and the knob of the pre-tightening mechanism (6) is adjusted to achieve elastic contact between the slider (2) and the driving foot (3.5);

[0031] ② Input a sawtooth-shaped electrical signal to the piezoelectric stack (4). During the t0-t1 phase, the piezoelectric stack (4) is energized and slowly extends, pushing the support beam (3.3), causing the first-stage flexible amplification mechanism (3.2) to be stretched and the second-stage flexible amplification mechanism (3.4) to be compressed until the voltage amplitude no longer increases at time t1 and the deformation reaches a limit state. The extension of the piezoelectric stack (4) is converted into a displacement of the driving foot (3.5) in the positive x direction through the two-stage amplification mechanism (3), and the slider (2) moves x1 in the positive x direction under the action of the friction force;

[0032] ③ In the t1-t2 stage, the input voltage amplitude drops rapidly, the piezoelectric stack (4) contracts rapidly, the two-stage amplification mechanism (3) returns to the initial state, and the slider (2) produces a slight retreat x2 along the negative x direction under the action of the sliding friction force;

[0033] ④ Repeat the above steps, and the slider (2) can achieve a large stroke movement. The movement state of the slider (2) can be adjusted by adjusting the voltage amplitude and driving frequency of the electrical signal input to the piezoelectric stack (4).

[0034] See also Figure 5 The figure shows the relationship between the actual output speed v and the driving frequency f of a stick-slip piezoelectric actuator with a two-stage amplification mechanism of the present invention under the conditions of driving voltage U=100V and locking force F=2N. It can be seen that before 700Hz, the actual output speed v shows a trend of first increasing and then decreasing with the increase of the driving frequency f. The maximum speed occurs under the condition of driving frequency f=700Hz, and the maximum speed can reach 20.051mm / s.

[0035] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made to the present invention shall be included in the protection scope of the present invention.

Claims

1. A stick-slip piezoelectric actuator with a two-stage amplification mechanism, characterized in that: The driver comprises a base (1), a slider (2), a two-stage amplification mechanism (3), a piezoelectric stack (4), a wedge block (5) and a preload mechanism (6); the two-stage amplification mechanism (3) comprises a fixed beam (3.1), a first-stage flexible amplification mechanism (3.2), a support beam (3.3), a second-stage flexible amplification mechanism (3.4) and a driving foot (3.5) arranged along a positive y The slider (2) is mounted on one end of the boss of the base (1); a preload mechanism (6) for adjusting the preload force between the slider (2) and the driving foot (3.5) is fixedly mounted on the other end of the base (1); the piezoelectric stack (4) is preloaded and embedded in the first-stage flexible amplification mechanism (3.2) through a wedge block (5) and directly acts on the support beam (3.3); the piezoelectric stack (4) is periodically slowly extended and quickly contracted under the control of a sawtooth electrical signal, and the slider (2) is moved along the positive direction according to the stick-slip motion principle. x The first-stage flexible amplification mechanism (3.2) is composed of two x A parallelogram guide mechanism is formed by connecting the leaf-type flexible hinge Ⅰ (3.2.1) with an obtuse angle in parallel; the piezoelectric stack (4) is electrically extended Δ y 1, the first-stage flexible amplification mechanism (3.2) is deformed by the stretching action, and based on the principle of parasitic motion, the support beam (3.3), the second-stage flexible amplification mechanism (3.4) and the driving foot (3.5) generate a positive rotation as a whole. y Displacement Δ y 1, with a positive x Displacement Δ x 1; The second stage flexible amplification mechanism (3.4) is composed of two x A parallelogram guide mechanism is formed by connecting the leaf-type flexible hinge II (3.4.1) with an acute angle in parallel; the piezoelectric stack (4) is electrically extended Δ y 1, the second-stage flexible amplification mechanism (3.4) is deformed by compression, and the driving foot (5) also generates a positive x Displacement Δ x 2.

2. A driving method of a stick-slip piezoelectric actuator having a two-stage amplification mechanism, characterized in that: The stick-slip piezoelectric driver is a stick-slip piezoelectric driver with a two-stage amplification mechanism as claimed in claim 1, and the driving method comprises the following steps: ① The piezoelectric stack (4) and the wedge block (5) are embedded in the first-stage flexible amplification mechanism (3.2) in a tight fit manner; the two-stage amplification mechanism (3) is mounted on the preload mechanism (6) by means of screws, and the knob of the preload mechanism (6) is adjusted to achieve elastic contact between the slider (2) and the driving foot (3.5); ② Input a sawtooth-shaped electrical signal to the piezoelectric stack (4). Based on the inverse piezoelectric effect, the piezoelectric stack (4) is energized and slowly extends. Under the superposition of the displacement amplification of the first-stage flexible amplification mechanism (3.2) and the second-stage flexible amplification mechanism (3.4), the signal is converted into a positive displacement of the driving foot (3.5). x The displacement in the positive direction causes the slider (2) to move in the positive direction through friction. x Move to x 1, and satisfy the relationship x 1=Δ x 1+Δ x 2; Subsequently, the piezoelectric stack (4) loses power and contracts rapidly, the two-stage amplification mechanism (3) returns to its initial state, and the slider (2) moves along the negative x Slight regression x 2. Repeat the above two stages to achieve stable stepping; ③ By adjusting the voltage amplitude and driving frequency of the electrical signal input to the piezoelectric stack (4), the motion state of the slider (2) can be changed.

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