CN-121977738-A - High-sensitivity wide-frequency response piezoelectric high-temperature pressure sensor and assembly method

CN121977738ACN 121977738 ACN121977738 ACN 121977738ACN-121977738-A

Abstract

The invention belongs to the technical field of high-temperature dynamic pressure measurement and high-temperature gas sealing. The high-sensitivity wide-frequency response piezoelectric high-temperature pressure sensor and the assembly method are provided, a pressure-force conversion structure of a force transmission central column-annular metal diaphragm, a piezoelectric signal generating part of a plurality of reverse polarization parallel stacks and an acceleration compensating part based on an acceleration compensating inertial mass block are integrated on the same axial force transmission link, and a vacuum brazing airtight connector of a kovar alloy contact pin-alumina ceramic tube-metal shell is adopted to realize high-temperature reliable lead wires. The sensor housing is preferably made of high temperature alloy and is sealed in multiple stages by vacuum brazing and laser welding, so that the sensitive element works in a closed inner cavity with long-term high insulation and low leakage rate. The invention improves the contact stiffness and the charge collection stability, the typical sensitivity can be more than 1pC/kPa, the upper limit of the frequency response can reach 6000Hz, and the sensitivity drift can be controlled within 5 percent after long-term aging under the condition of 500 ℃.

Inventors

YU FAPENG
Yang Dingting
DUAN XIULAN
LI YANLU
ZHAO XIAN

Assignees

山东大学

Dates

Publication Date: 20260505
Application Date: 20260318

Claims (14)

1. The high-sensitivity wide-frequency response piezoelectric high-temperature pressure sensor is characterized by comprising a base shell, a force transmission mechanism, a signal generating part, an acceleration compensating part and a connector; the base shell is of an integral airtight structure, one end of the base shell is provided with a first mounting port for mounting the signal generating part, and the other end of the base shell is provided with a second mounting port for mounting the acceleration compensation part and the connector; The force transmission mechanism comprises a force transmission central column, an annular metal diaphragm and a diaphragm fixing nut, wherein the force transmission central column, the annular metal diaphragm and the diaphragm fixing nut are formed into a continuous rigid integrated structure through vacuum brazing so as to reduce a force transmission interface and shorten a force transmission path in the process that external pressure is transmitted to the signal generating part, the force transmission central column passes through the first mounting opening and forms airtight packaging with the base shell, the annular metal diaphragm is fixed at one end of the force transmission central column, and the diaphragm fixing nut is used for fixing the annular metal diaphragm; The signal generating part is coaxially sleeved on a section of the force transmission center column, which is positioned in the base shell and comprises a plurality of piezoelectric wafers, two-way electrode plates and insulating ceramics, the piezoelectric wafers are stacked along the axial direction and clamped between the two insulating ceramics, the polarization directions of the piezoelectric wafers are alternately reversed and are overlapped in a mode that the cathodes are opposite and the anodes are opposite, and the two-way electrode plates are respectively inserted into the anode interface and the cathode interface of the piezoelectric wafers to form two-way electric connection; The acceleration compensation part is positioned at one side of the signal generation part far away from the annular metal diaphragm and comprises a piezoelectric wafer for compensation, an acceleration compensation gasket, a compensation electrode plate and an acceleration compensation inertial mass block, wherein the acceleration compensation inertial mass block is arranged above the acceleration compensation gasket, the piezoelectric wafer for compensation is arranged below the acceleration compensation gasket, the compensation electrode plate is connected with the piezoelectric wafer for compensation, the connector is connected to the second mounting opening, and a metal contact pin in the connector is electrically connected with the two-way electrode plate and the compensation electrode plate through metal signal wires.
2. The high-sensitivity broadband piezoelectric high-temperature pressure sensor according to claim 1, wherein, The piezoelectric wafers are of annular structures and are coaxially sleeved on the outer side of the force transmission center column, the two-way electrode plates comprise a first-way electrode plate and a second-way electrode plate, the first-way electrode plate and the second-way electrode plate comprise a plurality of electrode rings and connecting sheets for connecting the adjacent electrode rings, and the electrode rings are clamped between the adjacent piezoelectric wafers or between the piezoelectric wafers and the insulating ceramics to form two independent conductive paths.
3. A high sensitivity broadband piezoelectric high temperature pressure sensor according to claim 2, wherein, The starting electrode ring of the first electrode plate is positioned between the bottommost piezoelectric wafer and the insulating ceramic below, the tail electrode ring of the first electrode plate is positioned between the two piezoelectric wafers at the uppermost layer, the starting electrode ring of the second electrode plate is positioned between the two piezoelectric wafers at the bottommost layer, and the tail electrode ring of the second electrode plate is positioned between the piezoelectric wafers at the uppermost layer and the insulating ceramic above, so that the two paths of electrode plates are arranged in a staggered manner in the signal generating part.
4. A high sensitivity broadband piezoelectric high temperature pressure sensor according to claim 2, wherein, The electrode ring is made of a platinum metal sheet or a platinum rhodium alloy sheet, and the upper surface and the lower surface of the piezoelectric wafer are both provided with a platinum thin film electrode layer which is in direct contact with the electrode ring.
5. A high sensitivity broadband piezoelectric high temperature pressure sensor according to claim 2, wherein, The piezoelectric wafer is made of tourmaline, quartz, gaPO 4 , LN, LGT, LGAT, CTGS, CTGAS or RECOB crystal or combination of the above crystals.
6. The high-sensitivity broadband piezoelectric high-temperature pressure sensor according to claim 1, wherein, The piezoelectric wafer for compensation comprises two reverse polarization compensation wafers, and insulating ceramics are respectively arranged at the upper part and the lower part of the two reverse polarization compensation wafers.
7. The high-sensitivity broadband piezoelectric high-temperature pressure sensor according to claim 1, wherein, The signal generating part also comprises a piezoelectric part pre-tightening nut, the piezoelectric part pre-tightening nut is matched with the connecting screw thread of the force transmission center column to compress the signal generating part, and the range of the pre-tightening moment applied by the piezoelectric part pre-tightening nut to the signal generating part is 0.35 N.m to 0.50 N.m.
8. The high-sensitivity broadband piezoelectric high-temperature pressure sensor according to claim 1, wherein, The acceleration compensation part also comprises a three-hole fastening nut which is screwed on the connecting screw thread of the force transmission center column and compresses the acceleration compensation inertial mass block on the acceleration compensation gasket.
9. The high-sensitivity broadband piezoelectric high-temperature pressure sensor according to claim 1, wherein, The connector comprises a metal shell, a ceramic tube and a metal contact pin, wherein the metal contact pin penetrates through the ceramic tube, the ceramic tube is fixed in the metal shell, the metal contact pin, the ceramic tube and the metal shell are in airtight connection through vacuum brazing, and the metal shell is fixed with a second mounting port of the base shell through laser welding.
10. The high-sensitivity broadband piezoelectric high-temperature pressure sensor according to claim 9, wherein, The base shell and the acceleration compensation inertial mass block are made of Inconel600 alloy, the force transmission center column and the annular metal membrane are made of Inconel718 alloy, and the insulating ceramic and the ceramic tube of the connector are made of alumina ceramic.
11. The high-sensitivity broadband piezoelectric high-temperature pressure sensor according to claim 1, wherein, The two-way electrode plate of the signal generating part and the compensating electrode plate of the acceleration compensating part are connected in an opposite charge mode in the base shell through a metal signal wire, so that charges generated by acceleration interference are mutually offset at the output end.
12. The high-sensitivity broadband piezoelectric high-temperature pressure sensor according to claim 1, wherein, The metal contact pin and the metal shell of the connector are made of kovar alloy, the metal contact pin and the ceramic tube are in interference fit, and are fixed by brazing under vacuum through silver-containing copper-titanium active brazing filler metal or nickel-based high-temperature brazing filler metal.
13. A method of assembling a high sensitivity wide frequency response piezoelectric high temperature pressure sensor according to any one of claims 1 to 12, comprising the steps of: cleaning and drying the piezoelectric wafer and forming a platinum thin film electrode layer on the surface; sleeving the insulating ceramic, the piezoelectric wafers and the two-way electrode plates on the force transmission center column in sequence, screwing in the pre-tightening nut, and applying pre-tightening force to form a signal generating part assembly; assembling a piezoelectric wafer for compensation, an acceleration compensation gasket, a compensation electrode plate and an acceleration compensation inertial mass block, and fixing the piezoelectric wafer, the acceleration compensation gasket, the compensation electrode plate and the acceleration compensation inertial mass block through three-hole fastening nuts to form an acceleration compensation part assembly; the metal contact pin, the ceramic tube and the metal shell are manufactured into a connector through vacuum brazing; The signal generating part component, the acceleration compensating part component and the connector are arranged in the base shell, electric connection is completed through the metal signal wire, the force transmission center column is welded with the base shell by utilizing vacuum brazing, and the connector is welded with the base shell by utilizing laser welding to form a closed inner cavity.
14. The method for assembling a high-sensitivity broadband piezoelectric high-temperature pressure sensor according to claim 13, Before the insulating ceramic, the piezoelectric wafers and the two-way electrode plates are sleeved on the force transmission center column, the annular metal diaphragm and the diaphragm fixing nut are cleaned, dried and coaxially clamped, and are brazed in a vacuum brazing furnace to form an integrated force transmission mechanism, and the integrated force transmission mechanism is coaxially assembled with the signal generating part after being cooled.

Description

High-sensitivity wide-frequency response piezoelectric high-temperature pressure sensor and assembly method Technical Field The invention relates to the technical field of high-temperature dynamic pressure measurement and high-temperature gas sealing, in particular to a high-sensitivity wide-frequency response piezoelectric high-temperature pressure sensor and an assembly method. Background The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art. In the scenes of a combustion chamber, a combustion section of a gas turbine, a scramjet engine, an internal combustion engine cylinder, a nuclear power main circuit and the like of an aerospace propulsion system, a pressure signal generally has the characteristics of high-frequency pulsation, strong impact, wide-spectrum noise and the like, and meanwhile, the working environment is accompanied with high temperature, high vibration, corrosive atmosphere and strong electromagnetic interference. The engineering attention points of pressure measurement are not only static measuring ranges, but also high-frequency bandwidth, linearity and anti-interference capability under transient impact, and stability and traceability under temperature cycle and long-term service conditions. Piezoelectric pressure sensors are widely used because of their high sensitivity, wide dynamic range, and high upper frequency response limit. Typical structures include force transfer mechanisms, piezoelectric sensing elements, pre-tension structures, electrode and insulating structures, housing packages, electrical connectors, and the like. The piezoelectric sensitive element generates charge output when being stressed, and a charge signal is converted into a voltage signal through a charge amplifier or an electrometer, so that pressure change measurement is realized. Compared with piezoresistance, capacitance and other schemes, the piezoelectric scheme has advantages in high-frequency dynamic pressure measurement, but the output of the piezoelectric scheme is a charge type signal, and is more sensitive to insulation and electric leakage. The conventional piezoelectric high-temperature pressure sensor has a plurality of key bottlenecks in engineering application, namely (1) charge signal attenuation caused by high-temperature insulation attenuation and electric leakage, zero drift increase and noise rise, (2) inherent frequency reduction caused by long force transmission path or multi-interface contact, limited upper frequency limit and increased phase lag of a structure, (3) pretightening force caused by thermal expansion mismatch drifts along with temperature to cause sensitivity and frequency response change, and repeatability deterioration, (4) acceleration coupling components overlap with a pressure frequency spectrum in strong vibration occasions, and pressure measurement precision is obviously reduced if effective compensation is lacking, and (5) high-temperature electrical connection reliability is insufficient, and conventional solder and a connector are easy to fail at more than 500 ℃ to cause contact resistance change, air tightness reduction or lead breakage. In addition, the traditional scheme often regards the improvement of sensitivity and the improvement of frequency response as contradictory targets, namely, the increase of the number and the stressed area of the piezoelectric sheets is beneficial to the improvement of charge output, but equivalent mass is increased or more interfaces are introduced, so that the natural frequency can be reduced, the improvement of the frequency response is often realized by reducing the structure size or improving the pretightening force, but the excessive pretightening force can also introduce the risk of wafer damage, the risk of diaphragm yielding or the nonlinearity of contact. Disclosure of Invention In order to solve the defects in the prior art, the invention provides a high-sensitivity wide-frequency response piezoelectric high-temperature pressure sensor and an assembly method thereof, which ensure that the sensor keeps high insulation and low leakage rate within the range of 0-650 ℃, the sensitivity drift is less than 5% after long-term aging under the condition of 500 ℃, the typical sensitivity can be more than 1pC/kPa, the upper limit of the frequency response can reach 6000Hz, and the acceleration coupling component is reduced by not less than 90% through a built-in acceleration compensation structure. In order to achieve the above purpose, the present invention adopts the following technical scheme: In a first aspect, the present invention provides a high sensitivity broadband piezoelectric high temperature pressure sensor. A high-sensitivity wide-frequency response piezoelectric high-temperature pressure sensor comprises a base shell, a force transmission mechanism, a signal generating part, an acceleration compensating part and a connect