Piezoelectric second-order system and high-temperature piezoelectric vibration sensor

Abstract

The utility model provides a kind of piezoelectric two-order system and high-temperature piezoelectric vibration sensor.The piezoelectric two-order system includes base, piezoelectric wafer, first electricity leading sheet, second electricity leading sheet, first mass, second mass, locking nut;The first electricity leading sheet, second electricity leading sheet are used to lead out the positive and negative electric charge generated by piezoelectric wafer;The piezoelectric wafer, first electricity leading sheet, second electricity leading sheet, first mass are all sleeved on stud, the locking nut is pressed on the outside of first mass and is connected with stud, piezoelectric wafer, first electricity leading sheet, second electricity leading sheet, first mass are fixed;The second mass is fixed on first mass, to be able to control sensor sensitivity by adjusting the mass of the second mass.Compared with prior art, the piezoelectric two-order system and high-temperature piezoelectric vibration sensor provided by the utility model can improve sensor sensitivity and ensure that the sensor works normally under high-temperature conditions.

Description

Technical Field

[0001] This utility model relates to the field of sensor technology, and in particular to a piezoelectric second-order system and a high-temperature piezoelectric vibration sensor. Background Technology

[0002] When vibrating in high-temperature environments, the sensor structure is affected by temperature. Long-term vibration can easily lead to functional degradation or even complete damage. Therefore, the requirements for the high-temperature resistance of sensors are quite stringent, especially in the aerospace and nuclear power energy fields, where the demands on sensors are increasingly stringent. For reliable monitoring, sensors need to be placed as close as possible to the high-temperature source; ensuring that sensors operate normally under high-temperature conditions is a critical issue.

[0003] The sensor's operating temperature is not high enough, which is limited by the performance of the core piezoelectric material and by an inadequate sensor structural design that fails to effectively utilize the anisotropy of the piezoelectric wafer to ensure the sensor's piezoelectric response at high temperatures. When the sensor is used under high-temperature vibration conditions, the sensor's structural components will undergo high-temperature deformation, the performance parameters of the high-temperature piezoelectric material will experience temperature drift, and the insulation performance of the high-temperature resistant insulating material will decrease, thus affecting the sensor's temperature characteristics. Especially in the operating temperature range above 500℃, the sensor's sensitivity can change by more than 15% (good sensors will have sensitivity fluctuations within 5%).

[0004] Therefore, designing a sensor that can be used in high-temperature environments is an urgent problem to be solved. Utility Model Content

[0005] To address the technical problems in the prior art, this utility model provides a piezoelectric second-order system and a high-temperature piezoelectric vibration sensor that can improve sensor sensitivity.

[0006] A piezoelectric second-order system includes a base, a piezoelectric wafer, a first lead-in sheet, a second lead-in sheet, a first mass block, a second mass block, and a locking nut. The first and second lead-in sheets are used to draw out the positive and negative charges generated by the piezoelectric wafer. The base includes a base body and a stud. The stud is disposed on the front surface of the base body. The piezoelectric wafer, the first lead-in sheet, the second lead-in sheet, and the first mass block are all provided with through holes and are sleeved on the stud. The locking nut presses against the outside of the first mass block and is connected to the stud, fixing the piezoelectric wafer, the first lead-in sheet, the second lead-in sheet, and the first mass block to the base. The second mass block is fixed to the first mass block, so that the sensor sensitivity can be controlled by adjusting the mass of the second mass block.

[0007] Preferably, the second mass block has a through hole and is sleeved on the stud, and is fixed to the first mass block by welding.

[0008] Preferably, the second mass block is provided with a receiving hole for accommodating a lock nut.

[0009] Preferably, the top periphery of the locking nut is provided with multiple grooves for inserting operating tools.

[0010] Preferably, the stud is integrally formed on the base and extends forward from the front surface of the base body.

[0011] Preferably, a positioning chamfer is provided at the connection between the front surface of the base body and the stud.

[0012] Preferably, the lower surface of the base body is a mounting surface with vertically arranged mounting through holes, and the upper surface of the base body is provided with stepped holes, with the stepped holes and the mounting through holes being interconnected.

[0013] Preferably, the mounting through hole has a chamfer on the side near the mounting surface of the base body.

[0014] Preferably, the first mass block has a radially connected hole that communicates with an axially connected hole to connect the inner and outer spaces.

[0015] Preferably, both the first mass block and the second mass block are square-shaped flat structures with rounded corners, have the same cross-sectional shape, and have flat sides.

[0016] Preferably, it further includes a first insulating pad and a second insulating pad, wherein the first insulating pad is attached to the side of the first mass block near the base body; the front surface of the base body is provided with an insulating pad mounting surface, and the second insulating pad is attached to the insulating pad mounting surface.

[0017] Preferably, there are four piezoelectric wafers stacked together; the first lead sheet includes three square disks bent to form a lead-in area, the three square disks are parallel to each other and connected in series, the inner end faces of the two outer square disks respectively contact the outer end faces of the first and fourth piezoelectric wafers, and the middle square disk is sandwiched between the second and third piezoelectric wafers; the second lead sheet includes two square disks bent to form a lead-in area, the two square disks are parallel to each other and connected in series, and are sandwiched between the first and second piezoelectric wafers and between the third and fourth piezoelectric wafers respectively; the first insulating pad is sandwiched between the first lead sheet and the first mass block, and the second insulating pad is sandwiched between the first lead sheet and the base body.

[0018] A high-temperature piezoelectric vibration sensor includes a piezoelectric second-order system as described above, as well as a housing, a cable, and a connector. The housing is fixed to the base body and is used to encapsulate the piezoelectric crystal, the first lead plate, the second lead plate, the first mass block, the second mass block, and the locking nut therein. The connector is connected to the piezoelectric second-order system via the cable to draw out the charge generated by the piezoelectric crystal.

[0019] Preferably, the outer shell is welded to the front of the base body, and the cable passes through the base body from the rear of the base and connects to the first lead plate and the second lead plate.

[0020] Preferably, the base body has a cable hole and two core wire holes arranged in the front-rear direction. The two core wire holes are located side by side on the front surface of the base body, and the cable hole is located on the rear surface of the base body. The cable hole and the two core wire holes are connected to each other to accommodate the cable and the two core wires stripped from the cable respectively. Each core wire at the front end of the cable is fitted with an insulating sleeve for isolating it from the base body.

[0021] Preferably, the core wire hole is located on the insulating pad mounting surface of the front surface of the base body; the front surface of the base body is also provided with a welding step for welding connection with the outer shell; a welding boss is provided at the cable hole.

[0022] Preferably, the device further includes a first connector and a second connector, wherein the first connector is used to connect the cable to the base body, and the second connector is used to connect the cable to the connector.

[0023] Preferably, the side wall of the second connector is provided with a filling hole for filling the internal cavity with glue, and the high-temperature piezoelectric vibration sensor is also provided with a plug for sealing the filling hole after filling with glue.

[0024] Compared with existing technologies, the piezoelectric second-order system and high-temperature piezoelectric vibration sensor provided by this utility model, by setting a second mass block fixed on the first mass block, allows for control of sensor sensitivity by adjusting the mass of the second mass block, thereby improving sensor sensitivity and ensuring normal operation of the sensor under high-temperature conditions. Furthermore, the second-order system and sensor described in this solution, when combined as a whole, effectively improve the high-temperature performance of the sensor, enabling it to operate continuously within a temperature range of -55℃ to 760℃, with an extreme operating temperature exceeding 800℃. Its compact structure meets the vibration monitoring requirements of aircraft and gas turbine engines in limited installation spaces; its sensitivity drift is less than 5%, superior to the industry standard of 15%; the sensor has strong resistance to environmental interference and achieves measurement conversion of sensor signals from high-temperature to low-temperature ends. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 An exploded perspective view of a high-temperature piezoelectric vibration sensor provided in one embodiment of the present invention; Figure 2 for Figure 1 The figure shows a cross-sectional view of the assembled high-temperature piezoelectric vibration sensor. Figure 3 for Figure 1 The cross-sectional view of the high-temperature piezoelectric vibration sensor assembly shown from another angle; Figure 4 for Figure 1 The image shows a cross-sectional view from another angle after the high-temperature piezoelectric vibration sensor assembly is shown. Figure 5 for Figure 1 The diagram shows a three-dimensional assembly of the second-order piezoelectric system in the high-temperature piezoelectric vibration sensor. Figure 6 for Figure 5 A cross-sectional view of the second-order piezoelectric system shown. Figure 7 for Figure 5 A three-dimensional view of the base in the second-order piezoelectric system shown; Figure 8 for Figure 7 A three-dimensional view of the base from another angle; Figure 9 for Figure 5 A three-dimensional view of the piezoelectric crystal in the second-order piezoelectric system shown. Figure 10 for Figure 5 A three-dimensional view of the first lead plate in the second-order piezoelectric system shown; Figure 11 for Figure 5 A three-dimensional view of the second lead plate in the piezoelectric second-order system shown; Figure 12 for Figure 5 A three-dimensional view of the first mass block in the second-order piezoelectric system shown. Figure 13 for Figure 5 A three-dimensional view of the second mass block in the piezoelectric second-order system shown; Figure 14 for Figure 5 A three-dimensional view of the locking nut in the second-order piezoelectric system shown; Figure 15 for Figure 1 A three-dimensional view of the housing of the high-temperature piezoelectric vibration sensor is shown. Figure 16 for Figure 1 The image shows a cross-sectional view of the cable in the high-temperature piezoelectric vibration sensor. Figure 17 for Figure 1 A perspective view of the first connector in the high-temperature piezoelectric vibration sensor shown; Figure 18 for Figure 1 A perspective view of the second connector in the high-temperature piezoelectric vibration sensor shown. Figure 19 for Figure 1 The image shows a 3D view of the plug in a high-temperature piezoelectric vibration sensor.

[0027] In the diagram, 1. Second-order piezoelectric system; 11. Base; 111. Base body; 112. Mounting through hole; 1121. Mounting clearance chamfer; 113. Stepped hole; 114. Cable hole; 115. Core wire hole; 116. Stud; 117. Insulating pad mounting surface; 118. Welding step; 119. Welding boss; 12. Piezoelectric wafer; 13. First lead plate; 14. Second lead plate; 15. First mass block; 151. Connecting hole; 16. Second mass block; 161. Receiving hole; 17. Locking nut; 171. Groove; 18. First insulating pad; 19. Second insulating pad; 2. Outer shell; 3. Cable; 31. Core wire; 4. Insulating sleeve; 5. Connector; 6. First connector; 7. Second connector; 71. Potting hole; 8. Plug. Detailed Implementation

[0028] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0029] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly set on the other component; when a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to the other component.

[0030] It should be noted that the structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which this application can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size should still fall within the scope of the technical content disclosed in this application, provided that they do not affect the effects and purposes that this application can produce.

[0031] This utility model provides a high-temperature piezoelectric vibration sensor, characterized in that it includes a second-order piezoelectric system 1, a housing 2, a cable 3, and a connector 5.

[0032] In this embodiment, the second-order piezoelectric system 1 includes a base 11, a piezoelectric wafer 12, a first lead sheet 13, a second lead sheet 14, a first mass block 15, a second mass block 16, and a locking nut 17.

[0033] The base 11 serves as a carrier for the piezoelectric wafer 12 and related components, and includes a base body 111 and a stud 116. The stud 116 is located on the front surface of the base body and extends forward from the front surface of the base body 111. In this embodiment, the stud 116 is integrally formed on the base 11; in other embodiments, the stud 116 may be an independent component, fixedly mounted on the base body 111. The front surface of the base body 111 is provided with an insulating pad mounting surface 117.

[0034] The lower surface of the base body 111 is a mounting surface, and it has a vertically arranged mounting through hole 112. The mounting through hole 112 has a chamfer 1121 on the side closest to the mounting surface of the base body 111 to prevent damage to the welding position and the mounting through hole 112 during surface treatment of the base body 111. The upper surface of the base body 111 has a stepped hole 113, which is connected to the mounting through hole 112. During testing, debugging, and installation, the sensor is fixed to the object under test using screws passing through the mounting through hole 112. The stepped hole 113 allows the screw head to sink into the base 11 after installation, facilitating installation in confined spaces.

[0035] The base body 111 also has a cable hole 114 and two core wire holes 115 arranged in the front-rear direction. The two core wire holes 115 are located side by side on the front surface of the base body 111, and the cable hole 114 is located on the rear surface of the base body 111. The cable hole 114 communicates with the two core wire holes 115 to accommodate the cable 3 and the two core wires 31 stripped from the cable 3, respectively. Specifically, the core wire holes 115 are located on the insulating pad mounting surface 117 on the front surface of the base body 111, and the cable holes 114 are located on the opposite side of the insulating pad mounting surface 117 of the base body 111. The front surface of the base body 111 also has a welding step 118 for welding connection with the outer shell 2 to ensure good fit between the base body 111 and the outer shell 2. A welding boss 119 is provided at the cable hole 114 to facilitate welding connection with mating components.

[0036] The piezoelectric wafer 12 is a device that generates the piezoelectric effect and is a sensitive element for measuring vibration and shock signals. In this embodiment, there are four piezoelectric wafers 12, which are stacked together. Each piezoelectric wafer 12 is made of piezoelectric material, has a thickness shear effect, can operate at temperatures above 800°C, and is shaped as a rectangular thin sheet.

[0037] The first lead-in sheet 13 and the second lead-in sheet 14 are used to draw out the positive and negative charges generated by the piezoelectric wafer 12. In this embodiment, the first lead-in sheet 13 includes three square discs bent to form a lead-in region. These three square discs are parallel to each other and connected in series. The inner end faces of the two outer square discs respectively contact the outer end faces of the first and fourth piezoelectric wafers, and the middle square disc is sandwiched between the second and third piezoelectric wafers. The first lead-in sheet 13 is provided with a charge extraction structure for drawing out the positive charge signal generated by the piezoelectric wafer 12. This charge extraction structure is led out from the square disc near one end of the base 11 and is located near the core wire hole 115 to facilitate its connection with the cable core wire.

[0038] In this embodiment, the second lead sheet 14 includes two square discs bent to form a lead-in region. The two square discs are parallel to each other and connected in series, respectively sandwiched between the first and second piezoelectric wafers and between the third and fourth piezoelectric wafers. One end of the second lead sheet 14 is provided with a charge extraction structure for extracting the negative charge signal generated by the piezoelectric wafer 12. This charge extraction structure is led out from the square disc near the base 11 and is located near the core wire hole 115 to facilitate its connection with the cable core wire.

[0039] In this embodiment, the first mass block 15 is the main component of the inertial mass block, and the second mass block 16 is an additional component of the inertial mass block, used to control the sensor sensitivity by adjusting the mass of the second mass block 16. Both the first mass block 15 and the second mass block 16 are flat, square structures with rounded corners, identical cross-sectional shapes, and flat surfaces on both sides. These rounded corners help control the welding strength between the first mass block 15 and the second mass block 16. The remaining flat surfaces, when used with tooling during the assembly of the piezoelectric second-order system 1, can restrict the rotation of the first mass block 15 and the second mass block 16.

[0040] In this embodiment, the through hole of the first mass block 15 matches the outer diameter of the stud 116, and a radially connected hole 151 is provided. This connected hole 151 communicates with the axial through hole to connect the inner and outer spaces. There are internal gaps between the stud 116 and the through holes of the piezoelectric wafer 12, the first lead plate 13, the second lead plate 14, and the first mass block 15, etc., and an external gap exists between the piezoelectric second-order system 1 and the inner wall of the outer shell 2. These internal and external gaps are provided to meet insulation requirements, and gas exists within these gaps. At high temperatures, the gas in the internal gaps will expand and contract due to heat, causing the piezoelectric wafer 12 to deform and compromising the stability of the sensor structure. Therefore, in this embodiment, the first mass block 15 is provided with a connected hole 151 to connect these two gaps, balancing the gas pressure on both sides of the piezoelectric wafer 12, thereby reducing the impact on the stability of the sensor structure caused by the thermal expansion and contraction of the gas in the internal gaps at high temperatures.

[0041] The second mass block 16 has a large receiving hole 161 in the middle, which matches the outer diameter of the locking nut 17 and is used to accommodate the locking nut 17. The second mass block 16 is fixed to the first mass block 15 by welding (or other fixing methods).

[0042] In this embodiment, the locking nut 17 has a threaded hole in the center that engages with the threaded post of the base 11, and the top periphery has multiple (four in this embodiment) grooves 171 for inserting operating tools to enhance process operability.

[0043] In this embodiment, the piezoelectric second-order system 1 further includes a first insulating pad 18 and a second insulating pad 19. The first insulating pad 18 is sandwiched between the first lead sheet 13 and the first mass block 15, with one side conforming to the side of the first mass block 15 near the base body 111, and the other side conforming to the outer end face of the square plate of the first lead sheet 13 near the first mass block 15. The second insulating pad 19 is sandwiched between the base 11 and the first lead sheet 13, with one side conforming to the insulating pad mounting surface 117 of the base body 111, and the other side conforming to the outer end face of the square plate of the first lead sheet 13 near the base body 111. The arrangement of the first insulating pad 18 and the second insulating pad 19 can isolate the first lead sheet 13 from the base 11 and the first mass block 15, preventing short circuits and ensuring the insulation withstand voltage performance between the sensor output and the sensor housing 2. Of course, other isolation methods can also be used in other embodiments. Both the first insulating pad 18 and the second insulating pad 19 are made of high-purity ceramic insulating material and are rectangular thin sheets with the same external dimensions as the piezoelectric crystal 12.

[0044] The piezoelectric wafer 12, the first conductive piece 13, the second conductive piece 14, the first insulating pad 18, the second insulating pad 19, and the first mass block 15 are all provided with through holes. During assembly, the piezoelectric wafer 12, the first conductive piece 13, the second conductive piece 14, the first insulating pad 18, the second insulating pad 19, and the first mass block 15 are all sleeved onto the stud 116 through their respective through holes. The locking nut 17 presses against the outside of the first mass block 15 and is connected to the stud 116, thus fixing the piezoelectric wafer 12, the first conductive piece 13, the second conductive piece 14, the insulating pad 18, and the first mass block 15. The locking nut 17 is accommodated in the receiving hole 161 of the second mass block 16.

[0045] In this embodiment, the outer shell 2 is fixed to the base body 111 by welding or other means to encapsulate the piezoelectric chip 12, the first lead sheet 13, the second lead sheet 14, the first mass block 15, the second mass block 16, and the locking nut 17 therein, so as to protect the internal components and at the same time play a role in sealing and shielding.

[0046] In this embodiment, connector 5 is connected to the piezoelectric second-order system 1 via cable 3 to draw out the charge generated by the piezoelectric chip 12 and provide an electrical interface for external connection. Connector 5 is a two-core connector 5, which can isolate the charge signal from the sensor housing 2. The threaded interface of connector 5 can be selected from different specifications such as 7 / 16-27UNS and M12.

[0047] In this embodiment, cable 3 is a two-core armored cable with two core wires 31 capable of transmitting positive and negative charge signals. The shell of cable 3 serves as a shielding layer and is connected to the connector shell. The space between the core wires 31 and the shell is filled with magnesium oxide powder, which has high insulation properties. Each core wire 31 at the front end of cable 3 is fitted with an insulating sleeve 4 for isolation from the base body 111. The insulating sleeve 4 is made of high-temperature resistant mica tube or quartz fiber tube.

[0048] In this embodiment, the high-temperature piezoelectric vibration sensor further includes a first connector 6 and a second connector 7. The first connector 6 is used for welding the cable 3 to the base body 111, and the second connector 7 is used for welding the cable 3 to the connector 5. The inner diameter of the first connector 6 is adapted to the diameter of the two-core armored cable, and a chamfer is provided on the cable side for welding. The welding boss 119 provided at the cable hole 114 of the base body 111 can also be easily welded to the first connector 6.

[0049] The inner diameter of the second connector 7 is adapted to the diameter of the two-core armored cable, and the cable side is chamfered for welding. Its sidewall has a potting hole 71 for filling the internal cavity with adhesive, and its end has a stepped hole 113 adapted to the connector 5. The internal cavity can be filled with insulating adhesive to improve the sensor's insulation performance and protect the welding structure between the two-core armored cable cores and the connector pins. Correspondingly, the high-temperature piezoelectric vibration sensor also has a plug 8 for sealing the potting hole 71 after adhesive filling. The plug 8 is a cylindrical structure with a chamfer for easy assembly with the second connector 7.

[0050] During assembly, the outer shell 2 is welded to the front of the base body 111, and the cable 3 passes through the base body 111 from the rear and connects to the first lead plate 13 and the second lead plate 14.

[0051] In this embodiment, the outer shell 2, base 11, locking nut 17, first connector 6, and second connector 7 are made of high-temperature nickel-based alloy, while the first mass block 15 and second mass block 16 are made of tungsten alloy. This ensures that the room-temperature expansion coefficients of the materials used in each structural component are relatively consistent. When combined, the thermal stress exerted on the piezoelectric crystal 12 by the structural components is minimal under conditions ranging from -55℃ to +760℃, allowing the overall sensitivity of the sensor to remain within a certain range without significant deviation. The high elastic modulus and good structural rigidity of each structural component, along with their high overall natural frequency, guarantee the measurement accuracy of the sensor at high temperatures.

[0052] Compared with the prior art, the piezoelectric second-order system and high-temperature piezoelectric vibration sensor provided by this utility model, by setting a second mass block 16 fixed on the first mass block 15, can control the sensor sensitivity by adjusting the mass of the second mass block 16, thereby improving the sensor sensitivity and ensuring that the sensor works normally under high temperature conditions.

[0053] The above description is merely an embodiment of this utility model. It should be noted that those skilled in the art can make improvements without departing from the inventive concept of this utility model, but these improvements all fall within the protection scope of this utility model.

Claims

1. A second-order piezoelectric system, characterized in that, It includes a base, a piezoelectric crystal, a first lead sheet, a second lead sheet, a first mass block, a second mass block, and a locking nut; The first and second lead-in plates are used to draw out the positive and negative charges generated by the piezoelectric crystal. The base includes a base body and a stud. The stud is disposed on the front surface of the base body. The piezoelectric crystal, the first lead-in plate, the second lead-in plate, and the first mass block are all provided with through holes and sleeved on the stud. The locking nut presses against the outside of the first mass block and is connected to the stud, fixing the piezoelectric crystal, the first lead-in plate, the second lead-in plate, and the first mass block to the base. The second mass block is fixed on the first mass block so that the sensor sensitivity can be controlled by adjusting the mass of the second mass block.

2. The piezoelectric second-order system as described in claim 1, characterized in that, The second mass block has a through hole and is fitted onto the stud, and is fixed to the first mass block by welding.

3. The piezoelectric second-order system as described in claim 1, characterized in that, The second mass block is provided with a receiving hole for accommodating a lock nut.

4. The piezoelectric second-order system as described in claim 1, characterized in that, The top periphery of the locking nut is provided with multiple grooves for inserting operating tools.

5. The piezoelectric second-order system as described in claim 1, characterized in that, The stud is integrally formed on the base and extends forward from the front surface of the base body.

6. The piezoelectric second-order system as described in claim 5, characterized in that, The connection between the front surface of the base body and the stud is provided with a positioning chamfer.

7. The piezoelectric second-order system as described in claim 1, characterized in that, The lower surface of the base body is a mounting surface with vertically arranged mounting through holes, and the upper surface of the base body is provided with stepped holes, which are connected to the mounting through holes.

8. The piezoelectric second-order system as described in claim 7, characterized in that, The mounting through hole has a chamfered edge on the side near the mounting surface of the base body.

9. The piezoelectric second-order system as described in claim 1, characterized in that, The first mass block has a radially connected hole that connects with an axially connected hole to connect the inner and outer spaces.

10. The piezoelectric second-order system as described in claim 1, characterized in that, Both the first mass block and the second mass block are flat, square-shaped structures with rounded corners, identical cross-sectional shapes, and planar sides.

11. The piezoelectric second-order system as described in claim 1, characterized in that, It also includes a first insulating pad and a second insulating pad, wherein the first insulating pad is attached to the side of the first mass block near the base body; the front surface of the base body is provided with an insulating pad mounting surface, and the second insulating pad is attached to the insulating pad mounting surface.

12. The piezoelectric second-order system as described in claim 11, characterized in that, The piezoelectric wafers are four in number and stacked together. The first lead sheet includes three square discs bent to form a lead-in region. The three square discs are parallel to each other and connected in series. The inner end faces of the two outer square discs respectively contact the outer end faces of the first and fourth piezoelectric wafers, and the middle square disc is sandwiched between the second and third piezoelectric wafers. The second lead sheet includes two square discs bent to form a lead-in region. The two square discs are parallel to each other and connected in series, and are sandwiched between the first and second piezoelectric wafers and between the third and fourth piezoelectric wafers, respectively. The first insulating pad is sandwiched between the first lead sheet and the first mass block, and the second insulating pad is sandwiched between the first lead sheet and the base body.

13. A high-temperature piezoelectric vibration sensor, characterized in that, Includes a piezoelectric second-order system as described in any one of claims 1 to 12, as well as a housing, cable, and connector. The housing is fixed to the base body and is used to encapsulate the piezoelectric wafer, the first lead plate, the second lead plate, the first mass block, the second mass block, and the locking nut therein. The connector is connected to the piezoelectric second-order system via a cable to draw out the charge generated by the piezoelectric chip.

14. The high-temperature piezoelectric vibration sensor as described in claim 13, characterized in that, The outer shell is welded to the front of the base body, and the cable passes through the base body from the rear of the base and connects to the first lead plate and the second lead plate.

15. The high-temperature piezoelectric vibration sensor as described in claim 14, characterized in that, The base body has a cable hole and two core wire holes arranged in the front-to-back direction. The two core wire holes are located side by side on the front surface of the base body, and the cable hole is located on the rear surface of the base body. The cable hole and the two core wire holes are connected to each other to accommodate the cable and the two core wires stripped from the cable respectively. Each core wire at the front end of the cable is fitted with an insulating sleeve for isolation from the base body.

16. The high-temperature piezoelectric vibration sensor as described in claim 15, characterized in that, The core wire hole is located on the insulating pad mounting surface of the front surface of the base body; the front surface of the base body is also provided with a welding step for welding connection with the outer shell; a welding boss is provided at the cable hole.

17. The high-temperature piezoelectric vibration sensor as described in claim 13, characterized in that, It also includes a first connector and a second connector, wherein the first connector is used to connect the cable to the base body and the second connector is used to connect the cable to the connector.

18. The high-temperature piezoelectric vibration sensor as described in claim 17, characterized in that, The second connector has a filling hole on its side wall for filling the internal cavity with glue, and the high-temperature piezoelectric vibration sensor also has a plug for sealing the filling hole after filling with glue.

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