Temperature-drift-resistant high-sensitivity micro-vibration sensor and measuring circuit thereof

Abstract

The invention discloses a temperature-drift-resistant high-sensitivity micro-vibration sensor and a measuring circuit thereof. The temperature-drift-resistant high-sensitivity micro-vibration sensor comprises a vibration sensing module and a measuring circuit module, a signal output by the vibration sensing module is conditioned by the measuring circuit module and then enters the data acquisition device; by adopting the two-stage piezoelectric bimorph design for the sensor, the two-stage piezoelectric bimorph can be connected in series to increase the sensitive area of a piezoelectric material under the condition of the same central mass, so that the measurement sensitivity of the sensor is improved, and the contradiction between the high sensitivity and the high-frequency measurement performance of the sensor is solved; by adopting the piezoelectric bimorph design and the precise differential amplification design for the output signal of the piezoelectric bimorph in the measurement circuit, the influence of the temperature effect of the piezoelectric material on the low-frequency measurement performance of the sensor can be avoided. And finally, high-precision measurement of micro vibration in a broadband range is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of sensors, and in particular relates to a temperature drift resistant high-sensitivity micro-vibration sensor and a measurement circuit thereof. Background Art

[0002] The principle of piezoelectric vibration sensor is to use the piezoelectric effect of piezoelectric ceramics or quartz crystals to convert vibration acceleration into electrical signals for measurement. It has the characteristics of small size, good dynamic response characteristics, strong anti-interference ability, etc., and has been widely used in vibration measurement and control systems. The continuous improvement of precision equipment vibration measurement and control requirements has put forward higher requirements on sensor technical indicators, requiring sensors to have lower measurement frequency bands and higher measurement sensitivity.

[0003] The low-frequency measurement performance of piezoelectric vibration sensors is mainly affected by the temperature effect of piezoelectric materials. The temperature effect will induce low-frequency drift of the sensor measurement signal, causing low-frequency measurement distortion. The commonly used method is to filter the low-frequency signal through the high-pass filter module in the subsequent signal conditioning circuit, but this method will also filter out the useful low-frequency vibration signal, limiting the low-frequency measurement bandwidth of the sensor. In addition, it is also an optional method to eliminate the influence of temperature drift by adding a compensation unit to the sensor for active compensation. However, the introduction of active compensation control will greatly increase the cost and implementation difficulty of the sensor. In addition, for a piezoelectric vibration sensor of a given piezoelectric material, its sensitivity increases with the increase of the center mass, and the center mass is limited by the size and mass of the sensor, and the increase of the center mass will reduce the natural frequency of the sensor structure, thereby affecting the high-frequency measurement performance of the sensor. Summary of the invention

[0004] In order to overcome the deficiencies of the prior art, the present invention provides a temperature drift resistant high-sensitivity micro-vibration sensor and its measurement circuit, including a vibration sensing module and a measurement circuit module; the signal output by the vibration sensing module is conditioned by the measurement circuit module and then enters the data acquisition device; by adopting a two-stage piezoelectric dual-chip design for the sensor, it is possible to increase the sensitive area of ​​the piezoelectric material by connecting the two-stage piezoelectric dual-chip in series under the same center mass, thereby improving the measurement sensitivity of the sensor, solving the contradiction between the high sensitivity of the sensor and the high-frequency measurement performance; by adopting a piezoelectric dual-chip design and a precise differential amplification design of the piezoelectric dual-chip output signal in the measurement circuit, it is possible to avoid the influence of the temperature effect of the piezoelectric material on the low-frequency measurement performance of the sensor, and at the same time, it is possible to achieve precise amplification of the weak measurement signal of the sensor for subsequent collection. Through the micro-vibration sensor and the measurement circuit design provided by the present invention, high-precision measurement of tiny vibrations within a wide frequency band is finally achieved.

[0005] The technical solution adopted by the present invention to solve the technical problem is as follows:

[0006] A temperature-drift-resistant, high-sensitivity micro-vibration sensor and a measuring circuit thereof, comprising a vibration sensing module and a measuring circuit module; the signal output by the vibration sensing module is conditioned by the measuring circuit module and then enters a data acquisition device;

[0007] The vibration sensing module includes a piezoelectric bimorph P1, a piezoelectric bimorph P2, a central mass block, a housing, an upper top plate, a lower top plate and a base;

[0008] The piezoelectric bimorph P1, piezoelectric bimorph P2 and central mass block are installed in the housing; the piezoelectric bimorph P1 is connected to the upper surface of the central mass block, and the piezoelectric bimorph P2 is connected to the lower surface of the central mass block; the upper and lower ends of the housing are fixedly connected to the upper top plate and the lower top plate respectively; the vibration sensor module is connected to the object to be measured through the base;

[0009] The piezoelectric bimorph P1 and the piezoelectric bimorph P2 have the same specifications;

[0010] The piezoelectric bimorph P1 and the piezoelectric bimorph P2 are composed of three parts: an upper piezoelectric sheet, a lower piezoelectric sheet and an intermediate metal sheet; the upper piezoelectric sheet is an upper electrode, the lower piezoelectric sheet is a lower electrode, and the intermediate metal sheet is a common electrode, which are respectively led out from the outlet holes on the shell through cables;

[0011] The measuring circuit module includes a DC isolation circuit A, a DC isolation circuit B, a differential amplifier S1, a differential amplifier S2, an adding circuit and a low-pass filtering circuit;

[0012] The DC isolation circuit A and the DC isolation circuit B are symmetrically arranged, and both include two capacitors C1 and two resistors R1 of the same specification and are symmetrically arranged; the differential amplifier S1 and the differential amplifier S2 are symmetrically arranged; the adding circuit includes two resistors R2 and a resistor R3 of the same specification and are symmetrically arranged, a precision voltage operational amplifier M and a resistor R4; the filtering circuit includes a resistor R5 and a capacitor C2;

[0013] The piezoelectric bimorph P1 and the piezoelectric bimorph P2 in the vibration sensing module respectively generate two positive and negative voltage signals representing vibration information, which enter the DC isolation circuit A and the DC isolation circuit B respectively through cables;

[0014] One end of the two capacitors C1 of the DC isolation circuit A is connected to the positive and negative signal interfaces of the piezoelectric bimorph P1, respectively, and the other ends of the two capacitors C1 are connected to the differential positive and negative input ends of the differential amplifier S1, respectively; one end of the two resistors R1 is connected to the differential positive and negative input ends of the differential amplifier S1, respectively, and the other end is grounded;

[0015] One end of the two capacitors C1 of the DC blocking circuit B is connected to the positive and negative signal interfaces of the piezoelectric bimorph P2, respectively, and the other ends of the two capacitors C1 are connected to the differential positive and negative input ends of the differential amplifier S2, respectively. One end of the two resistors R1 is connected to the differential positive and negative input ends of the differential amplifier S2, respectively, and the other ends are grounded.

[0016] The output ends of the differential amplifier S1 and the differential amplifier S2 are connected to the left ends of the resistors R2 and R3, respectively; the right end of the resistor R2 is connected to the negative input end of the precision voltage operational amplifier M; the right end of the resistor R3 is connected to the right end of the resistor R2; the positive input end of the precision voltage operational amplifier M is grounded; and the two ends of the resistor R4 are connected between the right end of the resistor R2 and the output end of the precision voltage operational amplifier M, respectively;

[0017] The two ends of the resistor R5 are respectively connected to the output end of the precision voltage operational amplifier M and the output end of the measurement circuit module; one end of the capacitor C2 is connected to the right end of the resistor R5, and the other end is grounded.

[0018] Preferably, the differential amplifier S1 and the differential amplifier S2 have the same specifications.

[0019] Preferably, the resistors R2, R3 and R4 have the same specifications.

[0020] Preferably, mounting bosses are respectively provided at upper and lower positions of the inner wall of the shell, and the piezoelectric bimorph P1 and the piezoelectric bimorph P2 are respectively placed on the upper and lower mounting bosses of the inner wall of the shell.

[0021] Preferably, the piezoelectric bimorph P1 and the piezoelectric bimorph P2 are connected and fixed to the upper and lower surfaces of the central mass block by bolts.

[0022] Preferably, the upper piezoelectric sheet and the lower piezoelectric sheet of the piezoelectric bimorph have the same specifications.

[0023] Preferably, the upper top plate and the lower top plate are designed with external threads, the outer shell is designed with internal threads, and the upper top plate, the lower top plate and the outer shell are connected by threads; the outer surfaces of the upper top plate and the lower top plate are designed with installation grooves, and are rotatably installed by tooling.

[0024] Preferably, the upper top plate cooperates with the upper mounting boss of the inner wall of the shell to clamp and fix the edge of the piezoelectric dual chip P1, and the lower top plate cooperates with the lower mounting boss of the inner wall of the shell to clamp and fix the edge of the piezoelectric dual chip P2.

[0025] Preferably, the piezoelectric sheet is made of low-capacitance quartz material.

[0026] The beneficial effects of the present invention are as follows:

[0027] (1) The present invention adopts a two-stage piezoelectric dual-chip design, which can improve the measurement sensitivity of the sensor under the same size and mass. Compared with the single-stage, single-chip design, the sensitivity is increased by four times, while ensuring the high-frequency measurement performance of the sensor;

[0028] (2) The present invention can effectively avoid the influence of the temperature effect of the piezoelectric material on the low-frequency measurement accuracy of the sensor by differentially processing the positive and negative signals of the upper and lower piezoelectric sheets of the piezoelectric bimorph.

[0029] (3) In the measurement circuit of the present invention, the constant deviation of the piezoelectric dual-chip output signal is isolated by a DC isolation circuit and then precisely amplified, which can improve the effective measurement amplitude of the sensor and achieve high-precision measurement of the sensor's tiny signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the structure of the micro-vibration sensor of the present invention;

[0031] Figure 2 The structure and output signal schematic diagram of the piezoelectric bimorph of the present invention;

[0032] Figure 3 This is a schematic diagram of the measurement circuit of the micro-vibration sensor of the present invention.

[0033] Figure markings: 1: piezoelectric bimorph P1, 2: piezoelectric bimorph P2, 3: central mass block, 4: outer shell, 5: upper top plate, 6: lower top plate, 1-1: upper piezoelectric sheet, 1-2: upper piezoelectric sheet, 1-3: middle metal sheet, a: upper electrode of piezoelectric bimorph, b: lower electrode of piezoelectric bimorph, c: common electrode of piezoelectric bimorph. DETAILED DESCRIPTION

[0034] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0035] The purpose of the present invention is to provide a high-sensitivity micro-vibration sensor with the function of suppressing temperature drift and a matching measurement circuit. By adopting a two-stage piezoelectric dual-chip design for the sensor, the two-stage piezoelectric dual-chip can be connected in series to increase the sensitive area of ​​the piezoelectric material under the same center mass, thereby improving the measurement sensitivity of the sensor, solving the contradiction between the high sensitivity of the sensor and the high-frequency measurement performance; in addition, by adopting a piezoelectric dual-chip design and a precise differential amplification design of the piezoelectric dual-chip output signal in the measurement circuit, the influence of the temperature effect of the piezoelectric material on the low-frequency measurement performance of the sensor can be avoided, and at the same time, the precise amplification of the weak measurement signal of the sensor can be achieved for subsequent collection. Through the micro-vibration sensor and the measurement circuit design provided by the present invention, high-precision measurement of tiny vibrations within a wide frequency band can be finally achieved.

[0036] To achieve the above object, the present invention provides the following technical solutions:

[0037] A temperature-drift-resistant, high-sensitivity micro-vibration sensor and its measuring circuit, comprising a vibration sensing module and a measuring circuit module. The signal output by the vibration sensing module is conditioned by the measuring circuit module and then enters other data acquisition devices;

[0038] The vibration sensing module includes a piezoelectric bimorph P1, a piezoelectric bimorph P2, a central mass block, a shell, an upper top plate, a lower top plate, and a base. The piezoelectric bimorph P1, the piezoelectric bimorph P2, and the central mass block are installed in the shell, and mounting bosses are respectively provided at the upper and lower positions of the inner wall of the shell. The piezoelectric bimorph P1 and P2 are respectively placed on the upper and lower mounting bosses of the inner wall of the shell, the piezoelectric bimorph P1 is connected to the upper surface of the central mass block, and the piezoelectric bimorph P2 is connected to the lower surface of the central mass block, and the two ends of the shell are respectively fixed to the upper top plate and the lower top plate.

[0039] The piezoelectric bimorph P1 and the piezoelectric bimorph P2 are connected and fixed to the upper and lower surfaces of the central mass block by bolts;

[0040] The piezoelectric bimorph P1 and the piezoelectric bimorph P2 have the same specifications;

[0041] The piezoelectric bimorph P1 and the piezoelectric bimorph P2 are respectively composed of an upper piezoelectric sheet, a lower piezoelectric sheet and an intermediate metal sheet. The upper piezoelectric sheet is an upper electrode, the lower piezoelectric sheet is a lower electrode, and the intermediate metal sheet is a common electrode, which are respectively led out from the outlet holes on the housing through cables;

[0042] The upper piezoelectric sheet and the lower piezoelectric sheet of the piezoelectric bimorph are of the same specifications;

[0043] The upper top plate and the lower top plate are designed with external threads, the outer shell is designed with internal threads, and the upper top plate, the lower top plate and the outer shell are connected by threads; the outer surfaces of the upper top plate and the lower top plate are designed with mounting grooves, and are rotatably mounted by tooling;

[0044] The upper top plate cooperates with the upper mounting boss of the inner wall of the housing to clamp and fix the edge of the piezoelectric bimorph P1, and the lower top plate cooperates with the lower mounting boss of the inner wall of the housing to clamp and fix the edge of the piezoelectric bimorph P2;

[0045] The measuring circuit module includes a DC isolation circuit (A and B), a differential amplifier (S1 and S2), an addition circuit and a low-pass filter circuit which are integrated in the same circuit board and connected in sequence. The DC isolation circuit A and the DC isolation circuit B are symmetrically arranged, and respectively include two capacitors C1 and two resistors R1 of the same specification which are symmetrically arranged; the differential amplifiers S1 and S2 are symmetrically arranged; the addition circuit includes two resistors R2 and R3 of the same specification which are symmetrically arranged, a precision voltage operational amplifier M and a resistor R4; the filter circuit includes a resistor R5 and a capacitor C2.

[0046] Due to the influence of the outside world, the piezoelectric bimorph P1 and the piezoelectric bimorph P2 in the vibration sensor module respectively generate two positive and negative voltage signals representing vibration information, which enter the DC isolation circuit A and the DC isolation circuit B respectively through cables;

[0047] One end of the two capacitors C1 of the DC isolation circuit A is respectively connected to the positive and negative signal interface of the piezoelectric dual chip P1, and the other end is respectively connected to the differential positive and negative input terminals of the differential amplifier S1, one end of the two resistors R1 is respectively connected between the capacitor C1 and the differential positive and negative input terminals of the differential amplifier S1, and the other end is grounded; one end of the two capacitors C1 of the DC isolation circuit B is respectively connected to the positive and negative signal interface of the piezoelectric dual chip P2, and the other end is respectively connected to the differential positive and negative input terminals of the differential amplifier S2, one end of the two resistors R1 is respectively connected between the capacitor C1 and the differential positive and negative input terminals of the differential amplifier S2, and the other end is grounded;

[0048] The output ends of the differential amplifier S1 and the differential amplifier S2 are respectively connected to the left ends of the adding circuit resistors R2 and R3, the right end of the resistor R2 is connected to the negative input end of the precision voltage operational amplifier M, the right end of the resistor R3 is connected to the right end of the resistor R2, the positive input end of the precision voltage operational amplifier M is grounded, and the two ends of the resistor R4 are respectively connected between the right end of the resistor R2 and the output end of the precision voltage operational amplifier M;

[0049] The two ends of the resistor R5 in the low-pass filter circuit are respectively connected to the output end of the precision voltage operational amplifier M and the output end of the measurement circuit module, one end of the capacitor C2 in the low-pass filter circuit is connected to the right end of the resistor R5, and the other end is grounded;

[0050] The differential amplifier S1 and the differential amplifier S2 have the same specifications.

[0051] The resistors R2, R3 and R4 have the same specifications.

[0052] Example:

[0053] like Figure 1As shown, a temperature drift resistant high-sensitivity micro-vibration sensor comprises a piezoelectric bimorph 1, a piezoelectric bimorph 2, a central mass block 3, a housing 4, an upper top plate 5, and a lower top plate 6. The piezoelectric bimorph 1, the piezoelectric bimorph 2, and the central mass block 3 are installed in the housing 4 and are sealed by the upper top plate 5 and the lower top plate 6;

[0054] like Figure 2 As shown, the piezoelectric bimorph 1 and the piezoelectric bimorph 2 are respectively composed of an upper piezoelectric sheet 1-1, a lower piezoelectric sheet 1-2, and an intermediate metal sheet 1-3, wherein the upper piezoelectric sheet 1-1 is an upper electrode a, the lower piezoelectric sheet 1-2 is a lower electrode b, and the intermediate metal sheet 1-3 is a common electrode c;

[0055] The piezoelectric bimorph 1 and the piezoelectric bimorph 2 are designed with a center hole at the center position; the upper and lower positions of the inner wall of the shell 4 are respectively provided with a mounting boss, an internal thread and a wire outlet hole, and the center position of the upper surface and the lower surface of the central mass block 3 is provided with a threaded hole; the edge positions of the upper top plate 5 and the lower top plate 6 are respectively designed with external threads; the center positions of the outer surfaces of the upper top plate 5 and the lower top plate 6 are respectively designed with mounting grooves;

[0056] The piezoelectric bimorph 1 is placed on the mounting boss on the upper inner wall of the housing 4, and the piezoelectric bimorph 1 and the central mass block 3 are bolted together via the center hole of the piezoelectric bimorph 1 and the threaded hole on the upper surface of the central mass block 3; the piezoelectric bimorph 2 is placed on the mounting boss on the lower inner wall of the housing 4, and the piezoelectric bimorph 2 and the central mass block 3 are bolted together via the center hole of the piezoelectric bimorph 2 and the threaded hole on the lower surface of the central mass block 3;

[0057] The upper top plate 5 is connected to the housing 4 by means of internal and external threads, and the upper top plate 5 cooperates with the upper mounting boss of the inner wall of the housing 4 to clamp and fix the edge of the piezoelectric bimorph 1; the lower top plate 6 is connected to the housing 4 by means of internal and external threads, and the lower top plate 6 cooperates with the lower mounting boss of the inner wall of the housing 4 to clamp and fix the edge of the piezoelectric bimorph 2;

[0058] The upper top plate 5 and the lower top plate 6 can be rotated through the mounting grooves and mounted in cooperation with the housing 4;

[0059] The output signals of the piezoelectric bimorph 1 and the piezoelectric bimorph 2 are respectively led out from the outlet holes on the housing 4 through cables;

[0060] In this embodiment, the piezoelectric bimorph 1 and the piezoelectric bimorph 2 have the same specifications, the upper piezoelectric sheet 1-1 and the lower piezoelectric sheet 1-2 have the same specifications, and the piezoelectric sheet is made of low-capacitance quartz material;

[0061] When the sensor is vibrated, due to inertia, the central mass block 3 will generate an inertial force proportional to the vibration it is subjected to and act on the piezoelectric bimorph 1 and the piezoelectric bimorph 2, thereby causing a charge change. In addition, temperature changes will also cause changes in the charge of the piezoelectric film, which will lead to changes in the output voltage. According to the sensor design, the electrode output voltages of the upper piezoelectric film 1-1 and the lower piezoelectric film 1-2 in the piezoelectric bimorph 1 and the upper piezoelectric film 1-1 and the lower piezoelectric film 1-2 in the piezoelectric bimorph 2 can be expressed as:

[0062]

[0063] Among them, Q v and Q T They represent the charge change caused by sensor vibration and temperature change respectively, and C is the capacitance of the piezoelectric film.

[0064] like Figure 3 As shown in the figure, the temperature drift resistant high sensitivity micro-vibration sensor measurement circuit comprises four parts: a DC isolation module I, a differential amplifier module II, an addition module III and a low-pass filter module IV.

[0065] The DC isolation module I includes a DC isolation circuit A and a DC isolation circuit B, which contain four capacitors C1 and a resistor R1 of the same specifications; the differential amplifier module II includes a differential amplifier S1 and a differential amplifier S2; the addition module III includes resistors R2, R3, R4 and a precision voltage operational amplifier M; the low-pass filter module IV includes a resistor R5 and a capacitor C2.

[0066] One end of the four capacitors C1 in the DC isolation module I is respectively connected to the upper electrode a and the lower electrode b signal interface of the piezoelectric bimorph 1 and the piezoelectric bimorph 2, and the other end is respectively connected to the differential positive and negative input ends of the differential amplifier S1, and one end of the four resistors R1 is respectively connected between the four capacitors C1 and the differential positive and negative input ends of the differential amplifier S1, and the other end is grounded;

[0067] The DC isolation module I forms an RC filter circuit through capacitor C1 and resistor R1 to filter out the DC bias signal in the output voltage of the piezoelectric film. The filter cutoff frequency will affect the lower limit measurement frequency of the sensor. By selecting appropriate C1 and R1 values, the DC isolation effect can be achieved while ensuring the low-frequency measurement performance of the sensor. The filter cutoff frequency of the DC isolation module I is f low =12πR1C1.

[0068] The differential amplifier S1 in the differential amplifier module II outputs a voltage V to the piezoelectric bimorph 1. 1a and V 1b Differential amplifier S2 piezoelectric bimorph 2 outputs voltage V2a and V 2b Differentiation and amplification are performed. The charge Q induced by temperature changes can be removed by differential processing. T The influence of differential amplifier S1 and differential amplifier S2 can be expressed as:

[0069] V1=k(V 1a -V 1b )=2kQ v C, V2=k(V 2a -V 2b )=2kQ v C (2)

[0070] Wherein, k is the constant amplification gain of the differential amplifier S1 and the differential amplifier S2.

[0071] The differential amplifier S1 and the differential amplifier S2 have the same specifications.

[0072] The left ends of the resistors R2 and R3 in the adding module III are respectively connected to the output ends of the differential amplifier S1 and the differential amplifier S2, the right end of the resistor R2 is connected to the negative input end of the precision voltage operational amplifier M, the right end of the resistor R3 is connected to the right end of the resistor R2, the positive input end of the precision voltage operational amplifier M is grounded, and the two ends of the resistor R4 are respectively connected between the right end of the resistor R2 and the output end of the precision voltage operational amplifier M;

[0073] The adding module III adds the voltages V1 and V2, thereby improving the voltage sensitivity of the sensor. The output voltage of the adding module is:

[0074] V3=V1+V2=4kQ v C (3)

[0075] The two ends of the resistor R5 in the low-pass filter module IV are respectively connected to the output end of the precision voltage operational amplifier M and the output end of the measurement circuit, one end of the capacitor C2 is connected to the right end of the resistor R5, and the other end is grounded;

[0076] The low-pass filter module IV forms an RC filter circuit through capacitor C2 and resistor R5 to filter out high-frequency noise signals in the sensor output voltage. The filter cutoff frequency will affect the upper limit measurement frequency of the sensor. The filter cutoff frequency of the low-pass filter module IV is f high =12πR5C2.

Claims

1. A high-sensitivity micro-vibration sensor with resistance to temperature drift and a measurement circuit thereof, characterized in that: It includes a vibration sensing module and a measuring circuit module; the signal output by the vibration sensing module is conditioned by the measuring circuit module and then enters the data acquisition device; The vibration sensing module includes a piezoelectric bimorph P1, a piezoelectric bimorph P2, a central mass block, a housing, an upper top plate, a lower top plate and a base; The piezoelectric bimorph P1, piezoelectric bimorph P2 and central mass block are installed in the housing; the piezoelectric bimorph P1 is connected to the upper surface of the central mass block, and the piezoelectric bimorph P2 is connected to the lower surface of the central mass block; the upper and lower ends of the housing are fixedly connected to the upper top plate and the lower top plate respectively; the vibration sensor module is connected to the object to be measured through the base; The piezoelectric bimorph P1 and the piezoelectric bimorph P2 have the same specifications; The piezoelectric bimorph P1 and the piezoelectric bimorph P2 are composed of three parts: an upper piezoelectric sheet, a lower piezoelectric sheet and an intermediate metal sheet; the upper piezoelectric sheet is an upper electrode, the lower piezoelectric sheet is a lower electrode, and the intermediate metal sheet is a common electrode, which are respectively led out from the outlet holes on the shell through cables; The measuring circuit module includes a DC isolation circuit A, a DC isolation circuit B, a differential amplifier S1, a differential amplifier S2, an adding circuit and a low-pass filtering circuit; The DC isolation circuit A and the DC isolation circuit B are symmetrically arranged, and both include two capacitors C1 and two resistors R1 of the same specification and are symmetrically arranged; the differential amplifier S1 and the differential amplifier S2 are symmetrically arranged; the adding circuit includes two resistors R2 and a resistor R3 of the same specification and are symmetrically arranged, a precision voltage operational amplifier M and a resistor R4; the filtering circuit includes a resistor R5 and a capacitor C2; The piezoelectric bimorph P1 and the piezoelectric bimorph P2 in the vibration sensing module respectively generate two positive and negative voltage signals representing vibration information, which enter the DC isolation circuit A and the DC isolation circuit B respectively through cables; One end of the two capacitors C1 of the DC isolation circuit A is connected to the positive and negative signal interfaces of the piezoelectric bimorph P1, respectively, and the other ends of the two capacitors C1 are connected to the differential positive and negative input ends of the differential amplifier S1, respectively; one end of the two resistors R1 is connected to the differential positive and negative input ends of the differential amplifier S1, respectively, and the other end is grounded; One end of the two capacitors C1 of the DC blocking circuit B is connected to the positive and negative signal interfaces of the piezoelectric bimorph P2, respectively, and the other ends of the two capacitors C1 are connected to the differential positive and negative input ends of the differential amplifier S2, respectively. One end of the two resistors R1 is connected to the differential positive and negative input ends of the differential amplifier S2, respectively, and the other ends are grounded. The output ends of the differential amplifier S1 and the differential amplifier S2 are connected to the left ends of the resistors R2 and R3, respectively; the right end of the resistor R2 is connected to the negative input end of the precision voltage operational amplifier M; the right end of the resistor R3 is connected to the right end of the resistor R2; the positive input end of the precision voltage operational amplifier M is grounded; and the two ends of the resistor R4 are connected between the right end of the resistor R2 and the output end of the precision voltage operational amplifier M, respectively; The two ends of the resistor R5 are respectively connected to the output end of the precision voltage operational amplifier M and the output end of the measurement circuit module; one end of the capacitor C2 is connected to the right end of the resistor R5, and the other end is grounded.

2. A temperature-drift-resistant high-sensitivity micro-vibration sensor and its measurement circuit according to claim 1, characterized in that: The differential amplifier S1 and the differential amplifier S2 have the same specifications.

3. The high-sensitivity micro-vibration sensor with resistance to temperature drift and its measurement circuit according to claim 1, characterized in that: The resistors R2, R3 and R4 have the same specifications.

4. The high-sensitivity micro-vibration sensor with resistance to temperature drift and its measurement circuit according to claim 1, characterized in that: The upper and lower positions of the inner wall of the shell are respectively provided with mounting bosses, and the piezoelectric bimorph P1 and the piezoelectric bimorph P2 are respectively placed on the upper and lower mounting bosses of the inner wall of the shell.

5. The high-sensitivity micro-vibration sensor with resistance to temperature drift and its measurement circuit according to claim 1, characterized in that: The piezoelectric bimorph P1 and the piezoelectric bimorph P2 are connected and fixed to the upper and lower surfaces of the central mass block by bolts.

6. The high-sensitivity micro-vibration sensor with resistance to temperature drift and its measurement circuit according to claim 1, characterized in that: The upper piezoelectric sheet and the lower piezoelectric sheet have the same specifications.

7. The high-sensitivity micro-vibration sensor with resistance to temperature drift and its measurement circuit according to claim 1, characterized in that: The upper top plate and the lower top plate are designed with external threads, the outer shell is designed with internal threads, and the upper top plate, the lower top plate and the outer shell are connected by threads; the outer surfaces of the upper top plate and the lower top plate are designed with installation grooves, which are rotatably installed through tooling.

8. The high-sensitivity micro-vibration sensor with resistance to temperature drift and its measurement circuit according to claim 1, characterized in that: The upper top plate cooperates with the upper mounting boss of the inner wall of the shell to clamp and fix the edge of the piezoelectric dual chip P1, and the lower top plate cooperates with the lower mounting boss of the inner wall of the shell to clamp and fix the edge of the piezoelectric dual chip P2.

9. The high-sensitivity micro-vibration sensor with resistance to temperature drift and its measurement circuit according to claim 1, characterized in that: The piezoelectric sheet is made of low-capacitance quartz material.

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