CN105807085A - Bearing rotation measuring device based on piezoelectric properties and electrostatic induction - Google Patents

Abstract

The invention discloses a bearing rotation measuring device based on piezoelectric characteristics and electrostatic induction. The device includes a piezoelectric film ring that needs to be fixed on a rotating object, several piezoelectric film strips, an electrostatic sensor, an electrostatic signal detection circuit, a data acquisition module, and an analysis and processing module; a piezoelectric film ring and several piezoelectric film The film strips are evenly attached to the shaft; the two electrostatic sensors are respectively facing the two piezoelectric films; the two electrostatic signal detection circuits are respectively connected to the two electrostatic sensors, and the charges detected by the electrostatic sensors are amplified and filtered ; The electrostatic signal processed by the conditioning circuit is input to the analysis and processing module through the data acquisition module. The invention combines the advantages of piezoelectric effect and electrostatic induction, has more accurate measurement results, has the advantages of high sensitivity, simple structure and convenient operation. At the same time, the device has strong adaptability to the environment and can be widely used in the production process.

Description

A Bearing Rotation Measuring Device Based on Piezoelectric Characteristics and Electrostatic Induction

technical field

The invention belongs to the technical field of mechanical measurement, in particular to a detection device for bearing rotation parameters based on piezoelectric characteristics and electrostatic induction.

Background technique

In the process of mechanical rotation, the rotational speed and angular acceleration are very important parameters, which can intuitively reflect the operating status of the machine, especially the accuracy and real-time performance of the measurement results are extremely important indicators in the measurement process. Existing methods for measuring mechanical rotation are generally aimed at measuring the rotational speed of the machine. After measuring the rotational speed, the derivation can be obtained to obtain the change of acceleration. Compared with this method, the accuracy is relatively low. However, the existing methods for measuring rotational speed, including the The measurement results of these methods are greatly affected by the environment, and the reliability is low, which puts forward requirements for the adaptability of the measuring instrument to the harsh environment. In recent years, due to the advantages of simple structure and high sensitivity, electrostatic sensors have been used more and more in measuring speed, and the most widely used method is the correlation method. In recent years, there has not been a good measurement method for the measurement of the angular acceleration of the rotating shaft. Generally, the adjacent angular velocities are measured by using a magnetoelectric sensor, and the average angular acceleration of the rotating shaft is obtained by solving the rate of change of the two angular velocities before and after. So far there is no method for measuring instantaneous acceleration. Piezoelectric materials have the characteristic that the charge generated is proportional to the pressure and have been widely used. The effective combination of the characteristics of piezoelectric materials generating charges under force and the characteristics of electrostatic sensor induced charges can greatly improve the accuracy of the measurement results of electrostatic sensors. How to effectively combine the two is the difficulty of research.

Contents of the invention

The purpose of the present invention is to overcome the defects of the above-mentioned prior art, and propose a bearing rotation measurement device based on piezoelectric characteristics and electrostatic induction, which has high accuracy and reliability in measuring rotational speed and strong environmental adaptability.

The purpose of the present invention is achieved by the following technical solutions:

A parameter detection device for bearing rotation, including a piezoelectric film ring fixed on the rotating shaft, several piezoelectric film strips fixed on the rotating shaft, two electrostatic sensors and subsequent signal processing circuits, a piezoelectric film ring and Several strips of piezoelectric film are parallel and evenly attached to the shaft. The two electrostatic sensors are long strips, which are parallel to the shaft and opposite to the two piezoelectric films when installed; two static detection circuits are respectively connected to the two electrostatic sensors. The sensors are connected to amplify and filter the electrostatic charge detected by the electrostatic sensor to obtain an electrostatic detection signal. The two static detection signals are input to the analysis and processing module through the data acquisition module for data processing.

The piezoelectric film ring is tightly wrapped around the shaft, with a width of 10-30mm, bonded to the metal surface of the shaft through J-2012 epoxy resin adhesive, installed on the surface of the shaft and parallel to the axial position of the shaft; the length of the piezoelectric film strip 3-10mm, the same width as the piezoelectric film ring, fixed by epoxy resin adhesive, and parallel to the piezoelectric film ring, the number is 1-10, and the center distance between the two is 50-80mm.

The electrostatic sensor is composed of an electrode and a shield, and the electrode is embedded inside the shield; the electrode of the electrostatic sensor is a thin strip, with a length of 10-30mm and a width of 1-5mm; 50mm, the radius of the shielding cover is adjusted according to the size of the shaft to be tested, generally 1.2-1.5 times the radius of the rotating shaft, and connected to the ground to achieve electrostatic shielding, the electrodes and the shielding cover are made of copper sheets, and the electrodes and the shielding cover are made of insulating materials connect.

The electrostatic conditioning circuit is a current-voltage conversion circuit, which is filtered and amplified.

The input signals of the analysis and processing module are two processed electrostatic signals, which can output the rotational speed and angular acceleration of the bearing after passing through the analysis and processing module.

The beneficial effects of the bearing rotation measuring device based on piezoelectric characteristics and electrostatic induction of the present invention are:

1) The present invention uses the charge generated by the piezoelectric effect as the induction source of electrostatic induction, converts the rotation information into charge information, realizes the accurate measurement of the mechanical speed, and overcomes the shortcomings of the traditional method with low accuracy;

2) The present invention analyzes the change of charge in the piezoelectric effect process, and corresponds the change of charge of the electrostatic sensor to the angular acceleration, realizes the real-time measurement of the angular acceleration, and overcomes the shortcoming of poor real-time performance of the traditional method.

The bearing rotation measurement device based on piezoelectric characteristics and electrostatic induction proposed by the invention has fast response speed, good real-time performance, accurate measurement results, simple measurement process, easy installation and good adaptability to the environment.

Description of drawings

Fig. 1 is a schematic diagram of the combination device of piezoelectric film and mechanical shaft;

Figure 2 is a schematic diagram of the relative position arrangement of the electrostatic sensor and the piezoelectric film;

Fig. 3 Structural diagram of measurement system for piezoelectric characteristics and electrostatic induction;

detailed description

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

As shown in Figure 1, the piezoelectric film material 3 is first fixed on the rotating shaft 1 through the J-2012 type epoxy resin adhesive 2, and its length direction is parallel to the rotating shaft; wherein, the piezoelectric film material includes a piezoelectric film ring 4 and several strips 5 of piezoelectric films.

As shown in accompanying drawing 2 and accompanying drawing 3, electrostatic sensor 8 and 9 all are made of electrostatic electrode 6 and shield cover 7, and electrostatic electrode 6 is axially installed against the rotating shaft and is connected with electrostatic sensor conditioning circuit 10, and electrostatic electrode 6 The insulating material is fixed inside the shielding case 7, and the shielding case 7 is grounded to form a shield and reduce the influence of external interference.

The bearing rotation measurement device based on the piezoelectric effect and electrostatic induction proposed by the present invention has a schematic structural diagram as shown in Figure 3, the piezoelectric film ring 4 and several piezoelectric film strips 5 are fixed on the rotating shaft, and the electrostatic sensors 8 and 9 are respectively For the piezoelectric films 4 and 5, the electrostatic sensors are connected to the electrostatic detection circuit 10, and the electrostatic detection signals output by the two electrostatic sensors are analyzed and processed by the data acquisition module 11 and the analysis processing module 12 to obtain the rotation speed and angular acceleration of the rotating shaft.

The working principle of the measurement method based on piezoelectric characteristics and electrostatic induction of bearing rotation is as follows: During the rotation of the shaft, due to the action of the adhesive, the two piezoelectric films bonded to the shaft will rotate with the shaft, and will be affected by the viscous force of the adhesive. The composite effect of gravity and the rotating shaft remain relatively static, so that the piezoelectric film will produce a piezoelectric effect on the force in the vertical direction of the piezoelectric film, and generate charges proportional to the force in this direction and evenly distribute on the surface of the piezoelectric film. And as the induction source of the electrostatic sensor, the rotation information is converted into charge information; when the rotating shaft rotates, the piezoelectric film strip 5 rotates at the same time, and the charge generated by it will also rotate accordingly, so that it is detected by the corresponding electrostatic sensor. Inducted by 9, the relative distance between the two changes periodically, and the induced charge of the electrostatic sensor will increase or decrease accordingly. This periodic change is related to the rotation speed v, which can be measured by the correlation speed measurement method The rotational speed of the rotating shaft; and for the piezoelectric film ring 4, since it is located on the entire surface of the circumference of the rotating shaft section, it is equivalent to that the relative distance from the electrostatic sensor 8 does not change, and the electrostatic sensor 8 opposite to it does not produce a periodic aspect Only the amount of induced charge is positively correlated with the amount of charge on the surface of the piezoelectric film. The amount of induced charge is related to the angular acceleration a and the rotational speed v; so the two-way electrostatic signal is passed through the electrostatic detection circuit 10 and the data acquisition module 11 to obtain the electrostatic detection signal, and in the analysis processing module 12, by aligning the piezoelectric film strip The rotational speed v can be obtained by performing correlation processing on the electrostatic detection signal, and the angular acceleration a can be obtained by analyzing and processing the amplitude of the electrostatic detection signal facing the piezoelectric film ring combined with the rotational speed.

The principle of measuring speed is as follows:

The principle of autocorrelation speed measurement by electrostatic method: It can be seen from the analysis that the electrostatic detection signal opposite to the piezoelectric film strip (2) is a periodic signal. According to the statistical characteristics of the received signal, the autocorrelation method can be used to extract the signal The cycle, so that the time required for one rotation is T seconds, then the speed v=60/T(r/min)(1)

The principle of measuring angular acceleration is as follows:

The detection signal of the electrostatic sensor opposite to the piezoelectric film ring 4 is a steady signal. During the rotation of the rotating shaft, the piezoelectric film ring 4 only responds to the force F perpendicular to the ring direction (F is the combined effect of gravity G and viscous force) Force) produces piezoelectric effect.

F＝mv ² /R(2)

In the formula: m is the quality of the piezoelectric film, v is the speed of mechanical rotation, and R is the radius of the rotating shaft.

The piezoelectric charge Q generated by the piezoelectric film ring 4 is proportional to F, and the charge q sensed by the electrostatic sensor 8 is proportional to Q (that is, proportional to F), and the conditioning circuit 10 for the electrostatic sensor is actually provided to the electrode through a current-to-voltage circuit A charge discharge path on the chip generates a current, and after passing through the operational amplifier circuit, a voltage proportional to the current is generated, that is, the amplitude U of the output voltage is proportional to the change rate dq/dt of the induced charge.

U=k*dF/dt=2kmv*(dv/dt); (3)

In the formula: U is the output voltage of the electrostatic detection circuit, k is a constant, m is the quality of the piezoelectric film, v is the speed of mechanical rotation, and R is the radius of the rotating shaft.

v is the tangential velocity of the rotating shaft, that is, the rotational speed of the rotating shaft, and dv/dt is the angular acceleration of the rotating shaft. Through analysis, it can be found that the electrostatic detection signal facing the piezoelectric film ring is proportional to the rotational speed and angular acceleration.

U=K*v*a(4)

In the formula: U is the output voltage of the electrostatic detection circuit, K is a constant, v is the speed of mechanical rotation, and a is the angular acceleration of the rotating shaft.

The real-time angular acceleration a can be obtained by determining K through the experimental calibration data, combined with the rotational speed v obtained by cross-correlation processing.

Claims (5)

1. the bearing rotation measuring device based on piezoelectric property and electrostatic induction, comprise a piezoelectric membrane ring being fixed in rotating shaft, several piezoelectric membrane strips being fixed in rotating shaft, two electrostatic transducers and follow-up signal and process circuit, it is characterized in that, one piezoelectric membrane ring is parallel with several piezoelectric membrane strips and uniformly fits on axle, two electrostatic transducers are strip, are parallel to rotating shaft and relative respectively with two piezoelectric membranes during installation；Two-way electrostatic detection circuit is connected with two electrostatic transducers respectively, electrostatic charge for being detected by electrostatic transducer obtains electrostatic detection signal after electric charge amplifies and filters, and two-way electrostatic detection signal is input to analysis and processing module by data acquisition module and it is carried out data process.

2. a kind of bearing rotation measuring device based on piezoelectric property and electrostatic induction according to claim 1, it is characterized in that, piezoelectric membrane ring was tightly around axle one week, width is 10-30mm, by J-2012 type epoxy resin stick and the bonding of rotating shaft metal surface, it is arranged on rotating shaft surface and parallel with rotating shaft axial location；Piezoelectric membrane strip length 3-10mm, wide identical with piezoelectric membrane ring width, and fixed by epoxy resin stick, and parallel with piezoelectric membrane ring, number takes 1-10, and both centre-to-centre spacing are 50-80mm.

3. a kind of bearing rotation measuring device based on piezoelectric property and electrostatic induction according to claim 1, it is characterised in that electrostatic transducer is made up of electrode and radome, and electrode is embedded in inside radome；Electrostatic transducer electrode is slice shape, and length is 10-30mm, wide for 1-5mm；Radome be cylindrical in outer radius difference 5-10mm, width 40-50mm, radome radius is 1.2-1.5 times of shaft radius, and is connected to ground and realizes electrostatic screen, and electrode and radome, by copper sheet making, are connected by insulant between electrode with radome.

4. a kind of bearing rotation measuring device based on piezoelectric property and electrostatic induction according to claim 1, it is characterised in that static conditioning circuit is current-to-voltage converting circuit, and it is filtered and processing and amplifying.

5. a kind of bearing rotation measuring device based on piezoelectric property and electrostatic induction according to claim 1, it is characterized in that, described analysis and processing module input signal is the treated electrostatic detection signal of two-way, is held speed and the angular acceleration of rotation by analysis and processing module rear output shaft.