CN115313910A - An Asymmetric Mass Piezo Inertial Actuator - Google Patents

Abstract

The invention relates to an asymmetric mass type piezoelectric inertia driver, and belongs to the technical field of piezoelectric precision driving. The motion body is sequentially provided with a mass block, a piezoelectric bimorph, a small clamping block, a large clamping block, a stepped shaft and an additional mass hollow shaft block from left to right; the outer surface of the small shaft of the stepped shaft adopts an anisotropic friction surface; when the piezoelectric bimorph works, the piezoelectric bimorph generates driving forces with the same magnitude under the excitation of the symmetrical square waves, the mass of a moving body is smaller than that of the moving body in the right half period when the driving device moves to the left in the first half period under the action of the anisotropic friction surface, and the mass of the moving body in one period is asymmetric, so that the directional driving of the driving device is realized.

Description

An Asymmetric Mass Piezoelectric Inertial Actuator

technical field

The invention belongs to the technical field of piezoelectric precision drive, and in particular relates to an asymmetric mass piezoelectric inertia driver.

Background technique

In recent years, the demand for precision positioning technology in precision measurement, ultra-precision machining, modern medical and other application fields has been increasing, which has greatly promoted the research and development of precision drives. Piezoelectric precision actuators have significant advantages such as large stroke, high precision, fast response, high load output, and no electromagnetic interference, which largely meet the requirements for precision positioning technology in these fields. According to different working principles and functions, piezoelectric precision drives can be divided into direct drive, inchworm drive, ultrasonic drive and inertial drive.

Among them, the working principle of the inertial drive is to achieve directional motion through the synergistic effect of inertial force and friction force. It has the characteristics of simple structure, fast frequency response, and miniaturization, and has become one of the research hotspots at home and abroad. The currently developed inertial drives can be divided into asymmetric signal control, asymmetric mechanical clamping control and asymmetric friction control according to different control methods.

Asymmetric signal control drivers generally use asymmetric excitation signals to generate asymmetric driving force to achieve directional drive, but this type of driver needs to establish a complex signal control system, which is not conducive to the miniaturization and integration of the driver; asymmetric mechanical clamping The control type generates an asymmetrical driving force by designing an asymmetrical mechanical clamping structure to match the symmetrical excitation signal to achieve directional drive. Although this type of drive greatly reduces the requirements of the signal control system, it has the problems of serious backlash and non-adjustable friction ;The asymmetric friction control driver adopts a symmetrical excitation signal and a symmetrical mechanical clamping structure, and realizes directional driving through the asymmetry of the friction force in the forward and backward direction. The problem will seriously affect the reliability, stability and life of the driver.

Contents of the invention

The present invention proposes an asymmetric mass type piezoelectric inertial driver. The embodiment adopted by the present invention is mainly composed of a moving body, a hollow shaft, an additional mass block and a base.

The moving body is provided with a mass block, a piezoelectric bimorph, a small clamping block, a large clamping block, and a stepped shaft from left to right; the mass block is fixedly installed on the free end of the piezoelectric bimorph; the piezoelectric bimorph is made of beryllium The bronze substrate and the piezoelectric sheet are bonded, and the piezoelectric sheet is located on the left and right sides of the beryllium bronze substrate; the fixed end of the piezoelectric bimorph is clamped symmetrically by the small clamping block and the large clamping block; the horizontal axis of the large clamping block Interference fit with the inner hole of the stepped shaft; the transition fit between the large shaft of the stepped shaft and the inner hole of the hollow shaft, the transition fit between the small shaft of the stepped shaft and the inner hole of the hollow shaft block with additional mass; the outer surface of the large shaft, the hollow shaft and the additional mass The friction coefficient of the inner surface of the hollow shaft block is 0.1; the outer surface of the small shaft adopts an anisotropic friction surface (as shown in Figure 5). The pentahedron is arranged, the height of the pentahedron is 0.1mm, the angle between the inclined surface of the pentahedron and the symmetrical central plane is 30°, the angle between the left inclined line and the horizontal line on the symmetrical central plane is 30°, the right The angle between the inclined line and the horizontal line is 60°, and the distance between two adjacent pentahedrons is 0.2mm; under the action of anisotropic friction surface, when there is relative motion between the small shaft and the hollow shaft block with additional mass , the friction coefficient is 0.2 when the small shaft moves to the left, and 0.4 when the small shaft moves to the right. Therefore, the friction force f ₁ when the small shaft moves to the left is smaller than the friction force f ₂ when the small shaft moves to the right, that is, the friction has Orientation dependent; the hollow shaft is fixedly mounted on the base.

During the working process, the hollow shaft is relatively static under the fixing effect of the base; when the piezoelectric bimorph bends to the right/left, the large clamping block and the ladder move to the left/right under the action of inertia; when the moving body moves to the left , due to the direction dependence of friction, the hollow shaft block with additional mass does not move with the small shaft of the stepped shaft under the action of friction, and is relatively static. At this time, the mass m ₁ of the moving body is the sum of the masses of the moving body; when the moving body When moving to the right, the additional mass hollow shaft block moves to the right together with the small axis of the stepped shaft under the action of friction force f2. At this time, the mass _m2 of the _moving body is the sum of the mass of the moving body and the additional mass hollow shaft block ; The mass of the additional mass hollow shaft block is m, and the mass relationship between them is m ₁ ≈ m ₂ -m.

In the present invention, the piezoelectric bimorph is clamped in a symmetrical clamping manner, and the left/right driving force produced when the piezoelectric bimorph bends to the right/left is equal in magnitude; Under the action, the mass m ₁ of the moving body when the driver moves to the left is smaller than the mass m ₂ of the moving body when the driver moves to the right.

Working method: Fig. 6 is a working principle diagram of an asymmetric mass piezoelectric inertia driver proposed by the present invention, and the driving process is carried out according to the following steps.

Step 1: When t=t ₁ , the moving body of the driver is in the initial state.

Step 2: When t=t ₁ -t ₂ , the piezoelectric bimorph rapidly deforms in the right direction, generating a driving force in the left direction. Under the action of anisotropic friction, the small shaft and the additional mass hollow shaft block The friction force is f ₁ , the additional mass hollow shaft block is stationary, the small clamping block, the large clamping block, the piezoelectric bimorph, the mass block and the stepped shaft move x ₁ to the left together, at this time, the mass of the moving body m ₁ is the sum of the masses of the small clamping block, the large clamping block, the piezoelectric bimorph, the mass block and the stepped shaft.

Step 3: When t=t ₂ -t ₃ , the piezoelectric bimorph rapidly deforms in the left direction and generates a driving force in the right direction. The friction force is f ₂ , the additional mass hollow shaft block, small clamping block, large clamping block, piezoelectric bimorph, mass block and stepped shaft move x ₂ to the right, at this time, the mass of the moving body m ₂ is the sum of the masses of the additional mass hollow shaft block, small clamping block, large clamping block, piezoelectric bimorph, mass block and stepped shaft.

Finally, under the excitation of a periodic symmetrical square wave signal, the actuator will move leftward by △ x (△ x = x ₁ - x ₂ ).

In the present invention, the symmetrical square wave excitation signal is used as the driving source of the driver, and the driver realizes the mass asymmetry of the moving body in the first half cycle and the second half cycle under the action of the anisotropic friction surface, and then, under the action of the asymmetric mass The drive realizes the directional movement.

Advantages and features: The asymmetric mass piezoelectric inertial driver proposed by the present invention uses a symmetrical square wave excitation signal to act on a symmetrical mechanically clamped piezoelectric vibrator as the driving source of the piezoelectric driver, and the piezoelectric vibrator generates driving forces of the same magnitude and opposite directions Matching asymmetric mass to realize directional drive has the advantages of simple structure and drive signal, good stability, reliable motion process, and no electromagnetic interference.

Description of drawings

Fig. 1 is a structural schematic diagram of a piezoelectric inertial driver with an asymmetric mass proposed by the present invention.

Fig. 2 is a schematic structural diagram of a moving body with an asymmetric mass piezoelectric inertial driver proposed by the present invention.

Fig. 3 is a structural sectional view of an asymmetric mass piezoelectric inertial driver in a preferred embodiment of the present invention.

Fig. 4 is a cross-sectional view along line A-A of Fig. 3 .

Fig. 5 is a schematic diagram of the friction surface of the asymmetric mass piezoelectric inertial driver proposed by the present invention.

Fig. 6 is a working principle diagram of the piezoelectric inertia driver with asymmetric mass proposed by the present invention.

Detailed ways

This embodiment is described in detail with reference to FIG. 1 and FIG. 2 . An asymmetric mass piezoelectric inertial driver described in this embodiment is mainly composed of a moving body 1 , a hollow shaft 2 , an additional mass hollow shaft block 3 and a base 4 .

The moving body 1 is provided with mass blocks 1-4, piezoelectric bimorphs 1-3, small clamping blocks 1-2, large clamping blocks 1-1, and stepped shafts 1-5 from left to right; mass blocks 1- 4 is fixedly installed on the free end of the piezoelectric bimorph 1-3; -3-2 is located on the left and right sides of the beryllium copper substrate 1-3-1; the fixed end of the piezoelectric bimorph 1-3 is symmetrically clamped by the small clamping block 1-2 and the large clamping block 1-1; the large clamping Interference fit between horizontal axis 1-1-1 of block 1-1 and inner hole 1-5-1 of stepped shaft 1-5; transition between large shaft 1-5-2 of stepped shaft 1-5 and inner hole of hollow shaft 2 Fitting, the small shaft 1-5-3 of the stepped shaft 1-5 is transitionally fitted with the inner hole of the additional mass hollow shaft block 3; the outer surface of the large shaft 1-5-2, the hollow shaft 2 and the inner hole of the additional mass hollow shaft block 3 The friction coefficient of the hole surface is 0.1; the outer surface of the small shaft 1-5-3 adopts an anisotropic friction surface (as shown in Figure 5), and the outer surface of the small shaft 1-5-3 is evenly distributed with 5 spines, each The root thorns are arranged by a single pentahedron a, the height H of the pentahedron a is 0.1 mm, the angle θ between the inclined surface a2 of the pentahedron a and the symmetrical central plane a1 is 30°, and the left side on the symmetrical central plane a1 The included angle α between the inclined line b1 and the horizontal line b3 is 30°, the included angle β between the right inclined line b2 and the horizontal line b3 is 60°, and the distance L between two adjacent pentahedrons a is 0.2mm; Under the action of the anisotropic friction surface, when there is relative motion between the small shaft 1-5-3 and the additional mass hollow shaft block 3, the friction coefficient of the small shaft 1-5-3 is 0.2 when the small shaft 1-5-3 moves to the left, and the small shaft 1-5 The coefficient of friction when -3 moves to the right is 0.4, therefore, the friction force f ₁ when the small shaft 1-5-3 moves to the left is smaller than the friction force f ₂ when it moves to the right, that is, the friction has direction dependence; the hollow shaft 2 Fixedly installed on the base 4.

During the working process, the hollow shaft 2 is relatively static under the fixing action of the base 4; when the piezoelectric bimorph 1-3 bends to the right/left, the large clamping block 1-1 and the stepped shaft 1-5 move downward under the action of inertia. Left/right movement; when the moving body 1 moves to the left, due to the direction dependence of the friction, the additional quality hollow shaft block 3 does not follow the small shaft 1-5-3 of the stepped shaft 1-5 under the action of the friction force f ₁ Movement, relatively static, at this time, the mass m ₁ of the moving body is the sum of the masses of the moving body 1; when the moving body 1 moves to the right, the additional mass hollow shaft block ₃ moves with the stepped shaft 1- The small shafts 1-5-3 of 5 move to the right together. At this moment, the quality m of the moving body is the mass sum of the moving body ₁ and the additional quality hollow shaft block 3; the quality of the additional quality hollow shaft block 3 is m; they The mass relationship between them is m ₁ ≈m ₂ -m.

In the present invention, the piezoelectric bimorph 1-3 is clamped in a symmetrical clamping manner, and the left/right driving force generated when the piezoelectric bimorph 1-3 bends to the right/left is equal in magnitude; Under the action of the anisotropic friction surface, the mass m ₁ of the moving body when the driver moves to the left is smaller than the mass m ₂ of the moving body when the driver moves to the right.

Working method: Fig. 6 is a working principle diagram of an asymmetric mass piezoelectric inertia driver proposed by the present invention, and the driving process is carried out according to the following steps.

Step 1: When t=t ₁ , the moving body of the driver is in the initial state.

Step 2: When t=t ₁ -t ₂ , the piezoelectric bimorph 1-3 rapidly deforms in the right direction, generating a driving force in the left direction. Under the action of anisotropic friction, the small axis 1-5- The friction force between 3 and the additional mass hollow shaft block 3 is f ₁ , the additional mass hollow shaft block 3 is stationary, the small clamping block 1-2, the large clamping block 1-1, the piezoelectric bimorph 1-3, and the mass block 1-4 and the stepped axis 1-5 have moved x ₁ to the left. At this time, the mass m ₁ of the moving body is the small clamping block 1-2, the large clamping block 1-1, and the piezoelectric bimorph 1-3 , the mass sum of masses 1-4 and stepped axes 1-5.

Step 3: When t=t ₂ -t ₃ , the piezoelectric bimorph 1-3 rapidly deforms in the left direction, generating a driving force in the right direction. Under the action of anisotropic friction, the small axis 1-5- The friction force between 3 and the additional mass hollow shaft block 3 is f ₂ , the additional mass hollow shaft block 3, the small clamping block 1-2, the large clamping block 1-1, the piezoelectric bimorph 1-3, and the mass block 1 -4 moved x ₂ to the right together with the stepped shaft 1-5. At this time, the mass m ₂ of the moving body is the additional mass of the hollow shaft block 3, the small clamping block 1-2, the large clamping block 1-1, the pressing The mass sum of electric bimorph 1-3, mass block 1-4 and stepped shaft 1-5.

Finally, under the excitation of a periodic symmetrical square wave signal, the actuator will move leftward by △ x (△ x = x ₁ - x ₂ ).

In the present invention, the symmetrical square wave excitation signal is used as the driving source of the driver, and the driver realizes the mass asymmetry of the moving body in the first half cycle and the second half cycle under the action of the anisotropic friction surface, and then, under the action of the asymmetric mass The drive realizes the directional movement.

Claims (1)

1. An asymmetric mass type piezoelectric inertia driver mainly comprises a motion body, a hollow shaft, an additional mass hollow shaft block and a base; the method is characterized in that: applying a symmetrical square wave signal to the piezoelectric bimorph to control the piezoelectric bimorph to bend and deform rightwards/leftwards, wherein the left/right driving forces generated during bending and deformation of the piezoelectric bimorph are equal under the action of symmetrical clamping; when the piezoelectric bimorph is rapidly bent and deformed in the right direction to generate a driving force in the left direction, the additional mass hollow shaft block is relatively static under the action of anisotropic friction, and the moving body moves leftwardsx ₁ At this time, the mass m of the moving body ₁ Is the sum of the masses of the moving bodies; when the piezoelectric bimorph is rapidly bent and deformed in the left direction to generate a driving force in the right direction, the additional mass hollow shaft block and the moving body move rightwards together under the action of anisotropic frictionx ₂ At this time, the mass m of the moving body ₂ Is the sum of the masses of the additional mass hollow shaft block and the moving body; because of the mass m of the moving body when moving to the left ₁ Less than mass m of moving body in rightward movement ₂ Therefore, it isx ₁ >x ₂ Finally, the driver will move to the left by Δx(△x = x ₁ - x ₂ )。

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