CN101162875B - Thin Diameter Piston Type Piezoelectric Linear Motor - Google Patents

Abstract

The invention relates to a thin-diameter piston-type piezoelectric linear motor, comprising a tubular stator and a mover arranged inside the tubular stator. The stator comprises an upper and lower slender strip oscillators (the coupling heads at both ends of either oscillator are connected in a permanent manner, and the upper and lower lug bosses are arranged on both ends and supported on the inner wall of the tubular stator). The invention adopts a slender structure, and can be used for two-way driving and control; the invention is characterized in a simple structure and user-friendly functions.

Description

Thin Diameter Piston Type Piezoelectric Linear Motor

technical field

The invention relates to a miniature linear motor with both linear motion drive and control, in particular to a thin-diameter piston-type piezoelectric linear motor.

Background technique

With the development of electromechanical industry towards high precision, electromechanical products are rapidly miniaturized and thinned. In many fields such as information technology, semiconductor manufacturing, industrial testing, military cutting-edge equipment, biomedicine, aerospace, etc., the traditional linear motion drive method of screw plus rotary motor has become more and more difficult to meet the requirements, and there is an urgent need for hydraulic cylinders. Slim miniature linear motors are used as direct drives. However, the lateral size (perpendicular to the direction of linear motion output) of the currently developed miniature linear motors is generally too large, which limits its application in the above-mentioned fields.

To develop an ultra-fine linear micromotor, the most critical technical difficulty is that the stator and the mover must achieve effective force transmission with a small lateral size. Although there are examples of ultra-fine linear motors in foreign countries, the efficiency of the motors is obviously not high, and the production requirements of the parts are very precise and the cost is very expensive. Some drive signals are special (using sawtooth voltage waveforms), and some use very special Some components (piezoelectric stacks or piezoelectric films) are too small or too slow to be used as drives.

In the prior art, there is a micro linear actuator based on piezoelectric bicrystalline thin film (invention patent application number: 200510027281.0). It is a thin-diameter miniature linear actuator similar to a hydraulic cylinder. The mover is equivalent to the piston of the hydraulic cylinder, and the stator is equivalent to the cylinder body of the hydraulic cylinder. There is no need to set additional clamping and pressing devices between the mover and the stator, so this design greatly reduces the lateral size of the piezoelectric linear actuator. But its main disadvantages are: 1) Since the piezoelectric film is arranged perpendicular to the moving direction of the mover, the diameter of the film cannot be too small, so it is difficult to further reduce the diameter of the driver structure; 2) The driver adopts a sawtooth waveform Drive signal, work in a non-resonant state. Therefore, its electromechanical energy conversion efficiency is not high, and the driving circuit is more complicated, which is not good for control; 3) due to the use of piezoelectric film, although it has the advantage of low voltage driving, it also increases the cost of the driver.

Contents of the invention

The object of the present invention is to provide a thin-diameter piston-type piezoelectric linear motor for bi-directional drive and control, aiming at the defects of the prior art. The structure is simple, no special process and components are used, and the drive and control are convenient.

In order to achieve the above objectives, the following technical measures are mainly adopted:

1) Bilateral volatility drive——

In the piezoelectric linear motor of the present invention, the driving force transmission interface is bilateral, that is to say, it is driven simultaneously on both sides of the stator or the mover. When the mover is a slider, the stator can be tubular, and the mover is on the The center is always in a self-holding state, without additional preloading and clamping mechanisms, so the transverse dimension is greatly reduced.

2) Encouraging traveling waves——

Traveling wave refers to a vibration wave propagating in a single direction. On the driving interface of an elastic body that vibrates as a traveling wave, there is no fixed peak and trough position. The direction of the friction force pushing the mover produced by the traveling wave fluctuation on the surface is consistent. In order to enable the slender mover to produce the effect of bilateral driving, so as to realize the driving effect on the inner wall of the pipe, the moving wave must be excited on the mover.

According to the wave theory, the simple harmonic vibration of two standing waves with a 90-degree difference in time phase can be synthesized into a traveling wave. This means that the necessary condition for exciting traveling wave vibration on a slender elastic body is that the elastic body has two bending resonance forms (hereinafter referred to as resonance forms as modes) with very close natural frequencies, one is approximately sinusoidal, The other approximates a cosine shape. In this way, as long as the piezoelectric ceramics are used to excite these two modes at the same frequency with a time phase difference of 90 degrees, traveling waves can be excited on the slender elastic body. The motor structure in the form of a double-layer slender sheet-shaped piezoelectric vibrator of the present invention has a sine vibration mode and a cosine vibration mode. Through conventional finite element computer-aided design, proper selection of the geometric dimensions of the motor can make the two natural frequencies very close.

When the motor is expected to move in the reverse direction, it is only necessary to change the signal originally excited with a positive 90-degree phase difference to a negative 90-degree phase difference.

3) Expand the amplitude——

Using piezoelectric ceramics to excite the flexural vibration of the elastic body has a very small amplitude and cannot produce effective frictional force transmission. Even if the resonance of the elastic body is used to amplify the vibration amplitude, since the present invention has a fine structure and a small size, the amplitude of the transverse bending vibration is still difficult to meet the driving requirements. For this reason, the present invention has adopted special amplitude amplifying mechanism, that is, at the two ends close to the length direction of the motor, respectively set flake-shaped or needle-shaped protrusions. Theoretical analysis shows that the fine protrusions on the elastic body can have obvious amplification effect on the vibration of the elastic body matrix. The resonant vibration of the motor body is effectively amplified at the needle tip to generate the elliptical motion required for driving, thereby realizing the linear motion of the motor in the pipeline.

4) Structural design of tubular guide rail——

The motor can have two working forms, one is that the motor mover (vibrator) acts as a slider and moves back and forth in a fixed pipeline; the other is to limit the movement of the motor mover along its length and drive the pipeline to move back and forth .

In order to ensure the smooth and good movement of the motor mover in the pipeline as the stator, the pipeline must have the function of applying and adjusting the positive pressure on the driving interface in addition to guiding. Regardless of where the mover is in the pipeline, the positive pressure mentioned above should be uniform, and the smaller the pressure fluctuation, the better. For this reason, the upper and lower working inner walls of the pipeline must always be kept parallel, and the distance cannot be fixed. The pressure of the pipeline on the driving surface of the motor rotor can be changed by changing the spring preload.

According to above-mentioned several technical measures, the present invention adopts following technical scheme:

A thin-diameter piston-type piezoelectric linear motor, comprising a tubular stator and a mover placed inside the tubular stator, characterized in that the mover is fixed by two upper and lower elongated sheet-shaped vibrators through the joints at both ends of the mover It is connected as a whole, and the two ends of the mover are supported by raised parts on the inner wall of the tubular stator.

The above-mentioned two thin and elongated sheet vibrators are composed of piezoelectric actuators pasted on the upper and lower surfaces of the narrow and elongated elastic metal sheet.

The above-mentioned piezoelectric actuator is a piezoelectric ceramic sheet whose upper and lower surfaces are uniformly coated with silver electrodes and polarized along the thickness direction.

A piece of piezoelectric actuator——piezoelectric ceramic sheet is attached to the center of the upper surface of the two narrow and long elastic metal sheets of the above-mentioned two slender sheet vibrators. The polarization directions of the two piezoelectric ceramic sheets are the same. ; and the lower surfaces of the two narrow strips of elastic metal sheets are symmetrically pasted with two piezoelectric actuators——piezoelectric ceramic sheets. The polarization directions of the two piezoelectric ceramic sheets are opposite, and the polarization directions of the two piezoelectric ceramic sheets on the left and right sides are the same as the two piezoelectric ceramic sheets on the left and right sides.

The above-mentioned signal access method for exciting the piezoelectric ceramic sheet: apply high-frequency alternating current to the two piezoelectric actuators—the piezoelectric ceramic sheet at the center of the upper surface of the upper and lower two elongated sheet vibrators. The simple harmonic excitation electric signal A applies the high-frequency alternating simple harmonic excitation electric signal B to the piezoelectric actuator on the lower surface——the piezoelectric ceramic sheet, and the excitation electric signal B between the excitation electric signal A and the excitation electric signal B The phase difference is 90 degrees; and the two narrow strips of elastic metal sheets of the two elongated sheet vibrators are grounded.

The structure of the connecting head of the above two slender sheet-shaped vibrators is as follows: the two ends of the upper and lower slender sheet-shaped vibrators are bent and glued together, and then fixed and connected by a bolt and a nut respectively; Alternatively, a whole block is processed in the middle of the upper and lower layers of elongated sheet-shaped vibrator, and the two ends maintain the original block three-dimensional rectangular body to form a connecting head.

The upper and lower protrusions at the two ends of the above-mentioned two elongated sheet vibrators are thin elastic sheets or thin elastic pins.

Compared with the prior art, the present invention has the following prominent substantive features and significant advantages:

1) The stator is only a casing, and the mover (the vibrator that outputs the motion) is a slender structure, so the lateral size of the motor is small;

2) The two sides of the motor work at the same time, there is no guiding and clamping mechanism, and the resonance work is used to make more effective use of the vibration energy generated by piezoelectric ceramics, with high electromechanical conversion rate and low power consumption;

3) The excitation waveform is two sinusoidal waveforms of the same frequency with a phase difference of 90 degrees, and the driving circuit is simple;

4) The structure is simple and easy to miniaturize, and the cost is low by using sheet-like rigid piezoelectric ceramics;

5) The output speed is stable and adjustable, so it can be used for more precise speed and position control, and can also be used for linear drive.

Description of drawings

Fig. 1 is a structural schematic diagram of an embodiment of the present invention.

Fig. 2 is a top view of the mover in the example of Fig. 1 .

Fig. 3 is a schematic structural diagram of another embodiment of the present invention.

Fig. 4 is a top view of the mover in the example of Fig. 3 .

Detailed ways

Embodiment one:

Referring to Fig. 1 and Fig. 2, the thin-diameter piston type piezoelectric linear motor includes a tubular stator 1 and a mover 13 placed in the tubular stator 1, and the mover 13 is composed of upper and lower layers of slender sheet-like vibrators 3, 9 and left and right End two coupling heads 6,12 are formed. The mover 13 is a left-right symmetrical structure. There are protrusions 2 symmetrically distributed above and below the mover 13 . The boss 2 is a thin elastic pin. The elongated sheet vibrator 3, 9 is composed of a narrow strip of elastic metal sheet and piezoelectric actuators 10, 5, 8, 11, 4, 7 pasted on its upper and lower surfaces. The piezoelectric actuator used here is a piezoelectric ceramic sheet uniformly coated with silver electrodes on the upper and lower sides and polarized along the thickness direction, so the piezoelectric actuator is referred to as a piezoelectric ceramic sheet hereinafter. When pasting, ensure that the polarization directions of piezoelectric actuators 4 and 5 piezoelectric ceramic sheets are in the same direction (for example, both upwards), and ensure that the polarization directions of piezoelectric actuators 10 and 11 piezoelectric ceramic sheets are in the same direction as piezoelectric actuators. The polarization directions of the piezoelectric ceramic sheet groups of moving parts 8 and 7 are different directions, and the same group of piezoelectric ceramic sheet polarization directions are in the same direction (for example, 10 and 11 are both downward, and 8 and 7 are both upward). The signal access mode for exciting the piezoelectric ceramic sheet is shown in Figure 1.

Working principle: Apply high-frequency alternating simple harmonic wave excitation voltage signals A and B to the piezoelectric ceramic sheet. The phase difference between the A-phase and B-phase signals is 90 degrees. The phase A signal can excite the approximately cosine-shaped resonant mode of the two sheet-shaped bending vibrators; the B-phase signal can excite the approximately sine-shaped resonant mode of the two sheet-shaped bending vibrators. According to the vibration theory, when the two vibration modes are excited at the same frequency and the phase difference of the two vibrations is 90 degrees, they can be synthesized into a traveling wave vibration. When the mover 13 vibrates in a traveling wave type, the tip of the raised part 2 vibrates on an elliptical track, and the amplitude is effectively amplified. At the same time, the track of the tip of the upper raised part turns and the track of the lower raised part turns. on the contrary. Therefore, when the mover 13 is placed in a straight-walled pipe and kept in close contact with the upper and lower pipe walls, the elliptical vibration at the tip of the raised portion generates linear motion by means of friction, and the mover 13 will move along the inner wall of the pipe. walk.

Using structural dynamic design, the design method is a general existing technology (such as using finite element analysis and design method), so that the structural size of the motor can meet two bending vibration modes (sine vibration mode and cosine vibration mode) The modal frequencies are basically the same.

In this embodiment, the structure of the connecting heads 6 and 12 at the two ends of the upper and lower elongated sheet vibrators 3 and 9 is as follows: the two ends of the upper and lower elongated sheet vibrators 3 and 9 are bent and bonded together , and then each is fixed and connected into one body by a bolt and a nut. The protrusions 2 at the upper and lower ends of the two elongated sheet-like vibrators 3 and 9 are thin elastic pins.

Embodiment two:

Referring to Fig. 3 and Fig. 4, the thin-diameter piston-type piezoelectric linear motor is basically the same as the above-mentioned embodiment. The difference is that the structure of the connecting head 6, 12 is: a whole block, in the middle of which two layers of elongated vibrator 3, 9 are processed, and the two ends maintain the original block three-dimensional rectangular body to form the connecting head 6, 12. The protrusions 2 at the upper and lower ends of the two elongated sheet vibrators 3 and 9 are thin elastic sheets.

Claims (7)

1. slender diameter piston type piezoelectric straight line motor, comprise tubular stator (1) and place the interior mover (13) of tubular stator (1), it is characterized in that described mover (13) is by the coupling head (6 at its two ends by two elongated shape sheet oscillators (3,9) up and down, 12) fixedly connected being integral, and mover (13) both ends have lug boss (2) to be supported on the inwall of tubular stator (1) up and down.

2. slender diameter piston type piezoelectric straight line motor according to claim 1 is characterized in that described two elongated shape sheet oscillators (3,9) are to paste piezoelectric actuated (10,5,8,11,4,7) by two surfaces up and down of long narrow elastic sheet metal to constitute.

3. slender diameter piston type piezoelectric straight line motor according to claim 2, it is characterized in that described piezoelectric actuated (10,5,8,11,4,7) be upper and lower surface evenly apply galactic pole, along the piezoelectric ceramic piece of thickness direction polarization.

4. slender diameter piston type piezoelectric straight line motor according to claim 3, the upper face center that it is characterized in that two long narrow elastic sheet metals of described up and down two elongated shape sheet oscillators (3,9) is respectively pasted piezoelectric actuated of a slice (5,4)---piezoelectric ceramic piece, and the polarised direction of these two piezoelectric ceramic pieces is identical; And each left-right symmetric of the lower surface of two long narrow elastic sheet metals is pasted two piezoelectric actuated (10,8,11,7)---piezoelectric ceramic piece, the left side of these the four piezoelectric ceramic pieces polarised direction of two piezoelectric ceramic pieces up and down is incorgruous, the right polarised direction of two piezoelectric ceramic pieces up and down is incorgruous, the polarised direction of two piezoelectric ceramic pieces is identical on the right and left, and the polarised direction of following two piezoelectric ceramic pieces of the right and left is identical.

5. slender diameter piston type piezoelectric straight line motor according to claim 4, it is characterized in that piezoelectric actuated (5,4,10,11,8, the signal access way of excitation piezoelectric ceramic piece 7): to described two elongated shape sheet oscillators (3 up and down, 9) two piezoelectric actuated (5 of upper face center place, 4)---piezoelectric ceramic piece applies the excitation signal of telecommunication A of high frequency alternation monochromatic wave, to piezoelectric actuated (10 of its lower surface, 11,8,7)---piezoelectric ceramic piece applies the excitation signal of telecommunication B of high frequency alternation monochromatic wave, and the phase difference between excitation signal of telecommunication A and the excitation signal of telecommunication B is 90 degree; And two long narrow elastic sheet metal ground connection of two elongated shape sheet oscillators (3,9).

6. slender diameter piston type piezoelectric straight line motor according to claim 1, it is characterized in that the described structure of the two ends coupling head (6,12) of two elongated shape sheet oscillators (3,9) up and down is: fit and be integral in bending back in the both ends of two elongated shape sheet oscillators (3,9) up and down, then respectively respectively by fixedly connected being integral of screw bolt and nut; Perhaps, process two-layer elongated shape sheet oscillator (3,9) up and down therebetween, and two ends keep former bulk solid rectangle body to constitute coupling head (6,12) by a whole bulk.

7. slender diameter piston type piezoelectric straight line motor according to claim 1 is characterized in that described two elongated shape sheet oscillators (3,9) two ends lug boss (2) up and down is thin flexure strip or thin elasticity pin.

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