Resonance type asymmetric stiffness piezoelectric inertia driving linear motor

Abstract

The invention discloses a resonance type asymmetric rigidity piezoelectric inertia driving linear motor. The resonance type asymmetric rigidity piezoelectric inertia driving linear motor comprises a groove base and an inertia driving mechanism capable of moving relative to the groove base. The inertia driving mechanism comprises a main inertia body, a first inertia body, a second inertia body, a first piezoelectric displacement amplification mechanism and a second piezoelectric displacement amplification mechanism. According to the invention, two piezoelectric displacement amplification mechanisms with symmetrical rigidity can be obtained by adjusting the angle of the bevel edge of the rhombic displacement amplification mechanism, so that two effective vibration modes, namely a first longitudinal vibration mode and a second longitudinal vibration mode, can be obtained, and the ratio of inherent frequencies in the two effective vibration modes is 2: 1; by exciting the first piezoelectric displacement amplification mechanism and the second piezoelectric displacement amplification mechanism, the inertial driving mechanism can generate sinusoidal motion under the first longitudinal vibration mode inherent frequency and the second longitudinal vibration mode inherent frequency, frequency matching is convenient, and the power output capacity is improved.

Description

Technical Field

[0001] The present invention relates to the field of submicron-level piezoelectric precision displacement and driving technology, and more specifically to a resonant asymmetric stiffness piezoelectric inertia-driven linear motor. Background Art

[0002] With the continuous development of the micro-nano field, the requirements for precision positioning and displacement are constantly increasing. The traditional inchworm-type piezoelectric motor working in a non-resonant state has a complex structure and works at a relatively low frequency, resulting in a relatively low output speed; the traditional impact piezoelectric motor works in a quasi-static state with a relatively low speed and efficiency; and the traditional piezoelectric ultrasonic motor has serious wear problems due to friction and high heat loss, resulting in low motor efficiency. In order to solve the problem that piezoelectric motors working in a non-resonant state can only achieve miniaturization and precision positioning but cannot achieve high speed and high output power, some scholars have proposed a high-frequency resonant piezoelectric inertial drive linear platform, which achieves frequency matching by changing the mass of the inertial body, and the working speed can reach 14.6mm / s and the output power can reach 0.72mW. However, when changing the mass of the inertial body to achieve frequency matching, the mass of the second inertial body is too large, the overall mass ratio is quite different, and the structure is bulky. The proportion of kinetic energy of the main inertial body in the system under the two vibration modes is very different. Summary of the invention

[0003] The technical problem to be solved by the present invention is how to solve the problems of complex frequency matching method and low power output capacity when the mass is changed.

[0004] The present invention solves the above technical problems through the following technical means: a resonant asymmetric stiffness piezoelectric inertia-driven linear motor, comprising a groove base and an inertial drive mechanism capable of moving relative to the groove base; the inertial drive mechanism comprises a main inertial body, an inertial body 1, an inertial body 2, a piezoelectric displacement amplification mechanism 1, and a piezoelectric displacement amplification mechanism 2, one end of the main inertial body is connected to the inertial body 1 through the piezoelectric displacement amplification mechanism 1, and the other end is connected to the inertial body 2 through the piezoelectric displacement amplification mechanism 2; the piezoelectric displacement amplification mechanism 1 and the piezoelectric displacement amplification mechanism 2 have different stiffness; the piezoelectric displacement amplification mechanism 1 and the piezoelectric displacement amplification mechanism 2 are both provided with a rhombus displacement amplification mechanism; adjusting the hypotenuse angle of the rhombus displacement amplification mechanism can cause the piezoelectric displacement amplification mechanism 1 and the piezoelectric displacement amplification mechanism 2 to have different stiffness.

[0005] By adjusting the hypotenuse angle of the diamond-shaped displacement amplification mechanism, two piezoelectric displacement amplification mechanisms with symmetrical stiffness can be obtained, so that two effective vibration modes, a first longitudinal vibration mode and a second longitudinal vibration mode, can be obtained, so that the natural frequency ratio under the two effective vibration modes is 2:1, and by exciting the piezoelectric displacement amplification mechanism one and the piezoelectric displacement amplification mechanism two, the inertial drive mechanism can generate sinusoidal motion under the natural frequency of the first longitudinal vibration mode and the natural frequency of the second longitudinal vibration mode, so that the frequency matching is convenient and the power output capacity is improved.

[0006] As a preferred technical solution, a guide groove compatible with the inertial drive mechanism is provided on the groove base, a friction matrix is ​​provided in the guide groove, a friction gasket is fixedly connected to one end of the main inertial body facing the guide groove, and the inertial drive mechanism is slidably matched with the friction matrix through the friction gasket.

[0007] As a preferred technical solution, the inertial drive mechanism moves linearly along the guide groove.

[0008] As a preferred technical solution, the inertial body 1 and the inertial body 2 have the same mass, and the ratio of the mass of the inertial body 1 to the mass of the main inertial body is less than or equal to 1.

[0009] As a preferred technical solution, the piezoelectric displacement amplification mechanism 1 and the piezoelectric displacement amplification mechanism 2 are both provided with a piezoelectric stack, and the piezoelectric stack is adjustably connected in the rhombus displacement amplification mechanism and is located on a diagonal of the rhombus displacement amplification mechanism, and the connection direction of the piezoelectric stack, the inertial drive mechanism and the inertial body 2 is perpendicular.

[0010] As a preferred technical solution, the diamond-shaped displacement amplification mechanism includes four oblique sides connected in sequence and fixed at both ends. The four oblique sides are connected in sequence to form a diamond structure. One end of the piezoelectric stack is threadedly connected to the diamond-shaped displacement amplification mechanism, and the other end is threadedly connected to the diamond-shaped displacement amplification mechanism.

[0011] As a preferred technical solution, the piezoelectric displacement amplification mechanism 1 and the piezoelectric displacement amplification mechanism 2 are excited in phase to obtain the first longitudinal vibration mode, and the piezoelectric displacement amplification mechanism 1 and the piezoelectric displacement amplification mechanism 2 are excited in anti-phase to obtain the second longitudinal vibration mode.

[0012] As a preferred technical solution, the excitation piezoelectric displacement amplification mechanism 1 and the piezoelectric displacement amplification mechanism 2 can drive the inertial drive mechanism to generate sinusoidal motion at the natural frequency of the first longitudinal vibration mode and the natural frequency of the second longitudinal vibration mode.

[0013] As a preferred technical solution, the masses of the main inertial body and the inertial body 1 are 67.8g and 22.6g respectively.

[0014] As a preferred technical solution, the piezoelectric stack is a multi-layer stacked piezoelectric ceramic, and the main inertial body, inertial body one, inertial body two, and diamond-shaped flexible amplification mechanism are all made of 65Mn steel.

[0015] The beneficial effects of the present invention are:

[0016] (1) In the present invention, two piezoelectric displacement amplification mechanisms with symmetrical stiffness can be obtained by adjusting the hypotenuse angle of the diamond-shaped displacement amplification mechanism, so that two effective vibration modes, namely the first longitudinal vibration mode and the second longitudinal vibration mode, can be obtained, so that the natural frequency ratio under the two effective vibration modes is 2:1. By exciting the piezoelectric displacement amplification mechanism 1 and the piezoelectric displacement amplification mechanism 2, the inertial drive mechanism can generate sinusoidal motion under the natural frequency of the first longitudinal vibration mode and the natural frequency of the second longitudinal vibration mode. The maximum speed of the motor reaches 25.92 mm / s, and the output power can reach 2.55 mW. The frequency matching is convenient, and the power output capacity is improved.

[0017] (2) In the present invention, in order to make the inertial drive mechanism obtain a larger vibration amplitude, the piezoelectric displacement amplification mechanism 1 and the piezoelectric displacement amplification mechanism 2 are used to excite the first longitudinal vibration mode in phase and the piezoelectric displacement amplification mechanism 1 and the piezoelectric displacement amplification mechanism 2 are used to excite the second longitudinal vibration mode in anti-phase through impedance analysis, so that a higher vibration amplitude can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of the structure of a linear motor provided by an embodiment of the present invention;

[0019] Figure 2 A schematic diagram of the structure of an inertial drive mechanism provided in an embodiment of the present invention;

[0020] Figure 3 A schematic diagram of the guide groove structure provided by an embodiment of the present invention;

[0021] Figure 4 A schematic diagram of the structure of a piezoelectric displacement amplification mechanism provided by an embodiment of the present invention;

[0022] Figure 5 A schematic diagram of a cross-sectional structure of a friction matrix provided by an embodiment of the present invention;

[0023] Figure 6 A schematic diagram of a single spring mass dynamic model provided by an embodiment of the present invention, wherein the left figure is a structural schematic diagram and the right figure is a principle diagram;

[0024] Figure 7 A schematic diagram of a linear motor dynamics model provided by an embodiment of the present invention, wherein the upper figure is a structural schematic diagram and the lower figure is a principle diagram;

[0025] Figure 8A schematic diagram of a basic mode, a first longitudinal vibration mode, and a second longitudinal vibration mode provided by an embodiment of the present invention;

[0026] Fig. 9 A graph showing the first longitudinal natural frequency and the second longitudinal natural frequency along with the stiffness ratio of the piezoelectric displacement amplifying mechanism 1 and the piezoelectric displacement amplifying mechanism 2 provided in an embodiment of the present invention;

[0027] Fig.10 A diagram showing the ratio of the second longitudinal natural frequency to the first longitudinal natural frequency and the stiffness ratio of the piezoelectric displacement amplification mechanism 1 and the piezoelectric displacement amplification mechanism 2 provided in an embodiment of the present invention;

[0028] Fig.11 A diagram showing the relationship between the bevel angle and the stiffness provided by an embodiment of the present invention;

[0029] Fig.12 A graph showing the motion time and displacement of an inertial drive mechanism provided by an embodiment of the present invention;

[0030] Figure numbers: 1. groove base; 2. diamond-shaped flexible amplifying mechanism 1; 3. diamond-shaped flexible amplifying mechanism 2; 4. inertial body 2; 5. piezoelectric stack 2; 6. main inertial body; 7. piezoelectric stack 1; 8. inertial body 1; 9. friction base; 10. friction gasket. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] See also Figure 1 , Figure 5 A resonant asymmetric stiffness piezoelectric inertia-driven linear motor comprises a groove base 1 and an inertia-driven mechanism slidably connected in the groove base 1. A guide groove adapted to the inertia-driven mechanism is provided on the groove base 1. A friction matrix 9 is fixedly connected to one end of the guide groove facing the inertia-driven mechanism. The inertia-driven mechanism comprises a main inertia body 6, an inertia body 1 8, an inertia body 2 4, a piezoelectric displacement amplification mechanism 1, and a piezoelectric displacement amplification mechanism 2. The inertia-driven mechanism is placed in the guide groove by contacting a friction pad 10 fixed at the bottom of the main inertia body 6 with the friction matrix 9 at the bottom of the guide groove, and can move linearly along the guide groove.

[0033] See also Figure 2One end of the main inertial body 6 is connected to the inertial body 8 through the piezoelectric displacement amplification mechanism 1, and the other end is connected to the inertial body 2 4 through the piezoelectric displacement amplification mechanism 2. The connections are all fixed connections, which can be fixed by screw connection, bonding, snap connection and other fixing methods. The piezoelectric displacement amplification mechanism 1 and the piezoelectric displacement amplification mechanism 2 have different stiffness. The piezoelectric displacement amplification mechanism 1 includes a piezoelectric stack 17 and a rhombus-shaped flexible amplification mechanism 2. Piezoelectric ceramic sheets are bonded and fixed at both ends and the center of the piezoelectric stack 7. The two ends of the piezoelectric stack 7 are threadedly connected in the rhombus area of ​​the rhombus-shaped flexible amplification mechanism 2, and by adjusting the connection between the piezoelectric stack 17 and the rhombus-shaped flexible amplification mechanism 2, the length of a diagonal of the rhombus-shaped flexible amplification mechanism 2 can be adjusted, and the diagonal is perpendicular to the length direction of the groove base 1; the rhombus-shaped flexible amplification mechanism 2 includes four oblique sides connected in sequence, and the four oblique sides form a quadrilateral structure that is generally rhombus-shaped;

[0034] The piezoelectric displacement amplification mechanism 2 includes a piezoelectric stack 25 and a rhombus-shaped flexible amplification mechanism 23. Piezoelectric ceramic sheets are bonded and fixed to the two ends and the center of the piezoelectric stack 25. The two ends of the piezoelectric stack 25 are threadedly connected to the rhombus area of ​​the rhombus-shaped flexible amplification mechanism 23. By adjusting the connection between the piezoelectric stack 25 and the rhombus-shaped flexible amplification mechanism 23, the length of a diagonal line of the rhombus-shaped flexible amplification mechanism 23 can be adjusted, and the diagonal line is perpendicular to the length direction of the groove base 1.

[0035] See also Figure 4 The difference between the piezoelectric displacement amplification mechanism 1 and the piezoelectric displacement amplification mechanism 2 is that the α angles of the rhombus flexible amplification mechanism are different, wherein the α angles of the rhombus flexible amplification mechanism 1 2 and the rhombus flexible amplification mechanism 2 3 are different, and the α angle is the angle between one side of the rhombus flexible amplification mechanism and the piezoelectric stack. In this embodiment, it is the angle between the piezoelectric stack 2 5 and one side of the rhombus flexible amplification mechanism 2 3 or the angle between the piezoelectric stack 1 7 and one side of the rhombus flexible amplification mechanism 1 2.

[0036] It should be noted that the materials of the main inertial body 6, the inertial body 1 8, the inertial body 2 4, the rhombus flexible amplifying mechanism 1 2 and the rhombus flexible amplifying mechanism 2 3 are all 65Mn steel, and the piezoelectric stack 1 7 and the piezoelectric stack 2 5 are multi-layer stacked piezoelectric ceramics.

[0037] There are two effective vibration modes of the inertial drive mechanism in the guide groove, namely, the first longitudinal vibration mode excited in phase by the piezoelectric displacement amplification mechanism one and the piezoelectric displacement amplification mechanism two and the second longitudinal vibration mode excited in anti-phase by the piezoelectric displacement amplification mechanism, and the natural frequency ratio of the first longitudinal vibration mode and the second longitudinal vibration mode satisfies the relationship of 1:2.

[0038] Working principle of piezoelectric linear motor:

[0039] In this embodiment, the masses of the main inertial body 6, the inertial body 1 8 and the inertial body 2 4 are m0, m1 and m2 respectively, and the displacements are x0, x1 and x2 respectively; the stiffness of the piezoelectric displacement amplification mechanism 1 and the piezoelectric displacement amplification mechanism 2 are respectively denoted as k A and k B , kinematic modeling can be used to equate the inertial drive mechanism to a mass-spring-damper system. The influence of damping is ignored during the kinematic analysis. The kinematic equation is as follows:

[0040]

[0041] Solving the above mass-spring system, we can obtain the natural frequencies of the two effective vibration modes, expressed as:

[0042]

[0043]

[0044] In the above expression, p=m1 / m0, q=m2 / m0, r=k A / k B .

[0045] See also Figure 8 , Fig. 9 , Fig.10 , Fig.11 And the frequency expression, it can be concluded that the natural frequency of the first longitudinal vibration mode is f1, and the natural frequency of the second longitudinal vibration mode is f2; the movement direction of the main inertial body 6 in the two vibration modes is opposite, and the displacement direction and magnitude are related to the displacement magnitude and direction of the inertial body 1 8 and the inertial body 2 4; from the expression of the natural frequency, it can be seen that the frequency magnitude is related to the stiffness magnitude of the piezoelectric displacement amplification mechanism 1 and the piezoelectric displacement amplification mechanism 2, and the masses of the main inertial body 6, the inertial body 1 8 and the inertial body 2 4 are fixed. By adjusting the stiffness of the piezoelectric displacement amplification mechanism 1 and the piezoelectric displacement amplification mechanism 2, the two effective frequencies of the inertial drive mechanism can meet the relationship of 1:2; by exciting the piezoelectric displacement amplification mechanism 1 and the piezoelectric displacement amplification mechanism 2, the inertial drive mechanism generates sinusoidal motion under the natural frequency of the first longitudinal vibration mode and the natural frequency of the second longitudinal vibration mode, and the motion under the two natural frequencies is synthesized to make the main inertial body 6 generate asymmetric approximately sawtooth wave vibration.

[0046] In order to change the stiffness of the piezoelectric displacement amplification mechanism and to increase the vibration frequency and amplitude of the two longitudinal vibration modes, refer to Figure 6 , Figure 7The piezoelectric displacement amplification mechanism adopts a combination of a rhombus flexible amplification mechanism and a piezoelectric stack. By changing the hypotenuse angle of the rhombus flexible amplification mechanism 1 2 and / or the rhombus flexible amplification mechanism 2 3, a significant change in the stiffness of the piezoelectric displacement amplification mechanism can be achieved. The output force of the piezoelectric stack 1 7 and the piezoelectric stack 2 5 is large, which can improve the vibration amplitude and vibration frequency of the two longitudinal vibration modes. Through impedance analysis, it is concluded that when the first longitudinal vibration mode is excited in phase by the piezoelectric displacement amplification mechanism 1 and the piezoelectric displacement amplification mechanism 2, the main inertial body 6 can obtain a higher vibration amplitude; when the second longitudinal vibration mode is excited in anti-phase by the piezoelectric displacement amplification mechanism 1 and the piezoelectric displacement amplification mechanism 2, the main inertial body can obtain a higher amplitude.

[0047] In order to ensure that the mass and volume of the inertial drive mechanism are reasonable and the main inertial body 6 can obtain a larger amplitude, the mass of the inertial body 1 8 and the inertial body 2 4 is controlled to be 0 to 1 times the mass of the main inertial body, and the mass of the inertial body 1 8 and the inertial body 2 4 is equal. In this embodiment, the mass of the main inertial body 6 is 67.8g, and the mass of the inertial body 1 8 and the inertial body 2 4 is 22.6g. The frequency matching is achieved by adjusting the hypotenuse angle of the rhombus displacement amplification mechanism to change the stiffness of the piezoelectric displacement amplification mechanism. The method is simple and convenient. The maximum speed of the motor reaches 25.92mm / s, and the output power can reach 2.55mW.

[0048] See also Fig.12 The main inertial body 6 obtains an asymmetric approximately sawtooth wave vibration under the excitation of sinusoidal signals at two natural frequencies, and an asymmetric sliding friction is generated between the friction pad 10 at the bottom of the main inertial body 6 and the friction base 9 at the bottom of the guide groove, so that the inertial drive mechanism can realize unidirectional linear motion along the groove.

[0049] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A resonant asymmetric stiffness piezoelectric inertia driven linear motor, characterized in that: The invention comprises a groove base and an inertial drive mechanism capable of moving relative to the groove base; the inertial drive mechanism comprises a main inertial body, an inertial body 1, an inertial body 2, a piezoelectric displacement amplifying mechanism 1 and a piezoelectric displacement amplifying mechanism 2; one end of the main inertial body is connected to the inertial body 1 through the piezoelectric displacement amplifying mechanism 1, and the other end is connected to the inertial body 2 through the piezoelectric displacement amplifying mechanism 2; the piezoelectric displacement amplifying mechanism 1 and the piezoelectric displacement amplifying mechanism 2 have different stiffnesses; the piezoelectric displacement amplifying mechanism 1 and the piezoelectric displacement amplifying mechanism 2 are both provided with a rhombus displacement amplifying mechanism; adjusting the hypotenuse angle of the rhombus displacement amplifying mechanism can cause the piezoelectric displacement amplifying mechanism 1 and the piezoelectric displacement amplifying mechanism 2 to have different stiffnesses.

2. A resonant asymmetric stiffness piezoelectric inertia driven linear motor according to claim 1, characterized in that: The groove base is provided with a guide groove matched with the inertial drive mechanism, a friction matrix is ​​arranged in the guide groove, a friction pad is fixedly connected to one end of the main inertial body facing the guide groove, and the inertial drive mechanism is slidably matched with the friction matrix through the friction pad.

3. The resonant asymmetric stiffness piezoelectric inertia driven linear motor according to claim 2, characterized in that: The inertial driving mechanism moves linearly along the guide groove.

4. The resonant asymmetric stiffness piezoelectric inertia driven linear motor according to claim 1, characterized in that: The inertial body 1 and the inertial body 2 have the same mass, and the ratio of the mass of the inertial body 1 to the mass of the main inertial body is less than or equal to 1.

5. The resonant asymmetric stiffness piezoelectric inertia driven linear motor according to claim 1, characterized in that: The first piezoelectric displacement amplification mechanism and the second piezoelectric displacement amplification mechanism are both provided with a piezoelectric stack, which is adjustably connected in the rhombus displacement amplification mechanism and located on a diagonal line of the rhombus displacement amplification mechanism. The connection direction of the piezoelectric stack, the inertial drive mechanism and the second inertial body is perpendicular.

6. The resonant asymmetric stiffness piezoelectric inertia driven linear motor according to claim 5, characterized in that: The diamond displacement amplification mechanism includes four oblique sides connected in sequence and fixed at the ends. The four oblique sides are connected in sequence to form a diamond structure. One end of the piezoelectric stack is threadedly connected to the diamond displacement amplification mechanism, and the other end is threadedly connected to the diamond displacement amplification mechanism.

7. The resonant asymmetric stiffness piezoelectric inertia driven linear motor according to claim 1, characterized in that: The piezoelectric displacement amplifying mechanism 1 and the piezoelectric displacement amplifying mechanism 2 are excited in phase and can obtain a first longitudinal vibration mode, while the piezoelectric displacement amplifying mechanism 1 and the piezoelectric displacement amplifying mechanism 2 are excited in opposite phase and can obtain a second longitudinal vibration mode.

8. The resonant asymmetric stiffness piezoelectric inertia driven linear motor according to claim 7, characterized in that: The excitation piezoelectric displacement amplification mechanism 1 and the piezoelectric displacement amplification mechanism 2 can drive the inertial drive mechanism to generate sinusoidal motion at the first longitudinal vibration mode natural frequency and the second longitudinal vibration mode natural frequency.

9. The resonant asymmetric stiffness piezoelectric inertia driven linear motor according to claim 4, characterized in that: The masses of the main inertial body and the first inertial body are 67.8 g and 22.6 g respectively.

10. The resonant asymmetric stiffness piezoelectric inertia driven linear motor according to claim 5, characterized in that: The piezoelectric stack is a multi-layer stacked piezoelectric ceramic, and the main inertial body, the first inertial body, the second inertial body, and the diamond-shaped flexible amplification mechanism are all made of 65Mn steel.

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