阅读说明：本技术 一种高温振动加速度传感器及装配方法 (High-temperature vibration acceleration sensor and assembly method ) 是由 于法鹏 刘学良 姜超 房浩然 杨勇 赵显� 于 2020-05-22 设计创作，主要内容包括：本发明涉及一种高温振动加速度传感器及装配方法,属于电子材料与器件领域,包括底座外壳、信号发生部和连接器,信号发生部包括带有中心柱的顶盖和陶瓷管,陶瓷管上依次套放有多片压电晶片和质量块,多片压电晶片之间设置有两路电极片,陶瓷管上端连接有陶瓷螺母；压电晶片为(ZXl/θ)切BTS晶片,θ为40～50°；信号发生部倒装于底座外壳内,连接器包括金属插针,质量块与金属插针之间连接有金属信号线,连接器外壳和插针均采用可伐合金,插针、陶瓷管和外壳利用钎焊和过盈配合装配到一起。本发明结构简单稳定、低介电损耗、温度漂移小于5％,该传感器耐温高达700℃,并可在高达650℃的严苛环境下长时间服役。(The invention relates to a high-temperature vibration acceleration sensor and an assembly method thereof, belonging to the field of electronic materials and devices, and comprising a base shell, a signal generation part and a connector, wherein the signal generation part comprises a top cover with a central column and a ceramic tube; the piezoelectric wafer is a (ZXl/theta) cutting BTS wafer, and theta is 40-50 degrees; the signal generating part is inversely arranged in the base shell, the connector comprises a metal contact pin, a metal signal wire is connected between the mass block and the metal contact pin, the connector shell and the contact pin are made of kovar alloy, and the contact pin, the ceramic tube and the shell are assembled together by means of brazing and interference fit. The invention has simple and stable structure, low dielectric loss and temperature drift less than 5%, and the sensor can resist the temperature as high as 700 ℃ and can be used for a long time in a severe environment as high as 650 ℃.)

1. A high-temperature vibration acceleration sensor is characterized by comprising a base shell, a signal generating part and a connector, wherein the base shell is an integral device, the upper part of the base shell is provided with an installation port A for installing the signal generating part, the side edge of the base shell is provided with an installation port B for installing the connector, the base shell is fixedly connected with the signal generating part and the connector to form a closed inner cavity of the sensor, and two sides of the bottom of the base shell are respectively provided with a circular arc-shaped jaw;

the signal generating part comprises a top cover with a central column and a ceramic tube sleeved on the central column, the ceramic tube is fixed on the top cover, a plurality of piezoelectric wafers and a mass block are sequentially sleeved on the ceramic tube, two paths of electrode plates are arranged between the piezoelectric wafers, and a ceramic nut is connected to the upper end of the ceramic tube in a threaded manner and used for providing pre-tightening force for the mass block and the piezoelectric wafers;

the piezoelectric wafer is a (ZXl/theta) cutting BTS wafer, and theta is 40-50 degrees;

the signal generating part is inversely arranged in the base shell, the connector comprises a metal contact pin, and a metal signal wire is connected between the mass block and the metal contact pin.

2. The high-temperature vibration acceleration sensor according to claim 1, characterized in that θ is 45 °, the piezoelectric wafers are circular, a plurality of piezoelectric wafers are sleeved in parallel on the ceramic tube, and the electrodes of two adjacent piezoelectric wafers are opposite in direction, that is, the piezoelectric wafers are overlapped in parallel in a manner that the negative electrodes are opposite and the positive electrodes are opposite;

preferably, the piezoelectric wafer has a work roughness of 0.1 μm and a parallelism of 0.02 mm.

3. The high-temperature vibration acceleration sensor according to claim 2, characterized in that each electrode sheet comprises a plurality of electrode rings, adjacent electrode rings are connected in series through connecting wires, and the electrode rings are used for being clamped between piezoelectric wafers or between a piezoelectric wafer and a mass block/top cover;

the electrode ring of one path of electrode plate is inserted between the cathodes of the piezoelectric wafers, the electrode ring of the other path of electrode plate is inserted between the anodes of the piezoelectric wafers, and the piezoelectric wafers and the two paths of electrode plates form a crystal group.

4. The high-temperature vibration acceleration sensor according to claim 3, characterized in that the starting position of one path of electrode sheet is arranged between the lowest laminated wafer and the top cover, the tail end is arranged between the two uppermost piezoelectric wafers, the starting position of the other path of electrode sheet is arranged between the two lowest piezoelectric wafers, the tail end is arranged between the uppermost piezoelectric wafer and the mass block, and the number of the piezoelectric wafers is odd;

preferably, the electrode sheet is made of a nickel metal sheet.

5. The high temperature vibration acceleration sensor of claim 3, characterized in that, the inner diameter and the outer diameter of the electrode ring are kept the same size as the piezoelectric wafer.

6. The high-temperature vibration acceleration sensor of claim 1, characterized in that the connector further comprises a connector ceramic tube and a metal housing, and the metal pin, the connector ceramic tube and the metal housing are fixed together by a brazing technique;

the connector is welded on the mounting port B of the base shell;

preferably, the metal shell and the metal pin are made of kovar alloy, the ceramic tube, the connector ceramic tube and the ceramic nut are made of alumina ceramic, the purity of alumina is preferably 99.5%, a gold film with the thickness of 100nm is electroplated on the surface of the metal pin, and the metal signal wire is welded on the metal pin.

7. The high-temperature vibration acceleration sensor according to claim 1, characterized in that the mass block is made of Inconel718 alloy, and a platinum film with a thickness of 200-300nm is evaporated on the surface of the electrode plate and the surface of the mass block in contact with the electrode plate;

preferably, the base shell and the top cover are both made of Inconel601 alloy.

8. The high-temperature vibration acceleration sensor according to claim 1, characterized in that the mass block has a connection hole at its upper end, the diameter of the connection hole matches the outer diameter of the metal signal wire, and the metal signal wire is inserted into the connection hole and welded;

preferably, the diameter of the connecting hole is 1mm, the depth is 4mm, and the outer diameter of the metal signal wire is 1 mm.

9. The high-temperature vibration acceleration sensor according to claim 1, characterized in that the center post is provided with an external thread, the ceramic tube is provided with an internal thread matching with the external thread of the center post, and a high-temperature insulating glue is filled between the center post and the ceramic tube;

the ceramic nut is provided with internal threads, the ceramic nut is screwed into the central column, and the pre-tightening torque of the ceramic nut is 0.35-0.5 N.m;

preferably, a counter bore is arranged at one section of the mass block, which is in contact with the ceramic nut, and the ceramic nut is positioned in the counter bore after the assembly is completed.

10. A method of assembling a high temperature vibration acceleration sensor according to claim 1, characterized by comprising the steps of:

(1) pouring diluted high-temperature insulating glue into a ceramic tube with internal threads, and screwing the ceramic tube into the central column of the top cover in a rotating manner, wherein the ceramic tube is in close contact with the top cover without a gap;

(2) assembling a crystal group: plating a 200-plus-300 nm thick platinum film on the upper and lower surfaces of a piezoelectric wafer, superposing the piezoelectric wafers together in parallel in a manner that the negative electrodes are opposite and the positive electrodes are opposite, adding electrode plates between the piezoelectric wafers, respectively folding connecting wires of two electrode plates, respectively inserting an electrode ring of one electrode plate between the positive electrodes of the piezoelectric wafers, tightly contacting the electrode plate with a top cover, insulating the electrode plate from a mass block, arranging the initial position between the bottommost laminated wafer and the top cover, and positioning the tail end between the two uppermost piezoelectric wafers; the electrode ring of the other electrode plate is respectively inserted between the cathodes of the piezoelectric wafers, the initial position of the electrode ring is arranged between the two piezoelectric wafers at the bottom layer, the tail end of the electrode ring is arranged between the piezoelectric wafer at the top layer and the mass block, the electrode plate is tightly contacted with the mass block and is insulated with the top cover base, and the plurality of piezoelectric wafers and the two electrode plates form a crystal group;

(3) sleeving a crystal group and a mass block on a ceramic tube in sequence, pouring high-temperature insulating glue into threads of a ceramic nut, screwing the ceramic nut into a central column, tightly combining a top cover, the crystal group and the mass block together, putting the fixed top cover, the crystal group and the mass block into a drying box with the temperature of 150-180 ℃ for 12-18 hours, and completing the curing of the high-temperature insulating glue until the signal generating part is assembled;

(4) fixing the metal pin, the connector ceramic tube and the metal shell in a high-temperature vacuum brazing furnace by using a clamp, wherein the vacuum degree in the furnace is less than 10^-5Pa, controlling the temperature at 800-900 ℃, keeping the temperature for 5-6 hours to melt the high-temperature brazing filler metal, infiltrating the brazing filler metal into gaps among the ceramic tube of the connector, the metal contact pins and the metal shell through capillary action, and finishing the installation of the connector after annealing;

(5) placing the cured signal generating part, the base shell and the connector into an inert gas atmosphere box, wherein the gas pressure in the atmosphere box is higher than one atmospheric pressure, one end of a metal signal wire is inserted into the metal contact pin and welded well, the other end of the metal signal wire is inserted into a reserved connecting hole of the mass block and welded well, and the signal generating part and the connector are respectively placed at a mounting hole A and a mounting hole B and fixed well through a clamp;

(6) welding the signal generating part, the base shell and the connector together by laser welding to obtain a sensor;

(7) and (4) putting the welded sensor into a high-temperature box for annealing treatment, and eliminating stress residues among devices.

Technical Field

The invention relates to a high-temperature vibration acceleration sensor and an assembly method thereof, which are used for monitoring the health condition of key parts during mechanical operation in a high-temperature environment, can be used in the industries of aerospace, intelligent ships, rail trains, automobile industry, nuclear power energy and the like, and belong to the technical field of electronic materials and devices.

Background

When the medium is applied with external force, the upper and lower surfaces will generate charges with equal electric quantity and opposite signs, and when the external force is removed, it will return to the uncharged state, which is called piezoelectric effect. The crystal capable of generating piezoelectric effect is called piezoelectric crystal. The piezoelectric sensor can be developed into various piezoelectric sensing elements by utilizing the positive piezoelectric effect of the crystal, and can detect various non-electric physical quantities, such as deformation, displacement, pressure intensity, vibration, acceleration and the like. The piezoelectric acceleration sensor utilizes the piezoelectric effect principle of a piezoelectric crystal to measure dynamic pressure. Since the electricity-releasing performance of the piezoelectric material is related to the Curie point temperature of the material, the electrical performance of the piezoelectric material at high temperature is considered firstly when designing the sensor, so that the piezoelectric material suitable for the working temperature of the sensor is selected. When designing a high-temperature piezoelectric vibration sensor, multiple factors such as high-temperature resistance, thermal shock resistance, inertial shock structure, reasonable initial pretightening force, anti-interference capability and the like of each part need to be considered at the same time.

With the development of the world aerospace industry, the requirement of the aerospace engineering on the health monitoring of a high-performance engine is higher and higher. For example, in the monitoring of safe operation of a turbojet engine, real-time monitoring measurements of the main shaft and turbine blades of the engine are difficult. Because the internal temperature of the turbine engine is high during operation, the health monitoring high-temperature sensor for the tone wheel or the main shaft and the turbine blade in the market has the following problems: the problems of service performance failure at high temperature for a long time, large temperature deviation of transmission monitoring signals, short service life, weak anti-interference capability and the like are basically solved, and the system can not work in an extreme high-temperature environment for a long time.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides the high-temperature vibration acceleration sensor which has the advantages of simple and stable structure, low dielectric loss, small pyroelectric and less than 5% of temperature drift and the assembling method, and the sensor can resist the temperature of 700 ℃ and can be in service for a long time in the extreme environment of 650 ℃.

Interpretation of terms:

1. piezoelectric effect: when some dielectrics are deformed by an external force in a certain direction, polarization occurs in the dielectrics, and charges of opposite polarities appear on two opposite surfaces of the dielectrics. When the external force is removed, it can be restored to an uncharged state, and this phenomenon is called positive piezoelectric effect. Conversely, when an electric field is applied in the polarization direction of the dielectrics, these dielectrics also undergo deformation, and after the electric field is removed, the deformation of the dielectrics disappears, which is called the inverse piezoelectric effect.

2. BTS crystal: has a chemical formula of Ba₂TiSi₂O₈Belonging to the tetragonal system 4mm point group.

The invention adopts the following technical scheme:

a high-temperature vibration acceleration sensor comprises a base shell, a signal generating part and a connector, wherein the base shell is an integral device, the upper part of the base shell is provided with an installation port A for installing the signal generating part, the side edge of the base shell is provided with an installation port B for installing the connector, the base shell is fixedly connected with the signal generating part and the connector to form a closed inner cavity of the sensor, and two sides of the bottom of the base shell are respectively provided with an arc-shaped jaw for fixing the sensor;

the signal generating part comprises a top cover with a central column and a ceramic tube sleeved on the central column, the ceramic tube is fixed on the top cover (namely the ceramic tube is sleeved on the central column and is in contact with the top cover), a plurality of piezoelectric wafers and a mass block are sequentially sleeved on the ceramic tube, two paths of electrode plates are arranged between the piezoelectric wafers, and the upper end of the ceramic tube is in threaded connection with a ceramic nut for providing pretightening force for the mass block and the piezoelectric wafers and playing a role of insulating pretightening;

the piezoelectric wafer is a (ZXl/theta) BTS wafer, theta is 40-50 DEG, and the chemical formula is Ba₂TiSi₂O₈Belonging to the tetragonal system 4mm point group.

(ZXl/θ) means: z is the physical Z axis, X is the physical X axis, l is the rotation along the length of the wafer, and theta is the rotation along the length by a specific value theta.

Preferably, θ is 45 °.

The design has the advantages that the effective piezoelectric constant of the (ZXl/45) degree-cutting BTS wafer is 8.5pC/N, the range of room temperature to 700 ℃, the piezoelectric constant change rate is lower than 5 percent, the thermal expansion coefficient is linear change, and the crosstalk behavior is extremely low; the BTS wafer has the machining roughness of 0.1 mu m (the machining roughness is obtained when the pretightening moment among the piezoelectric wafer, the electrode plate and the mass block is 0.35-0.55 N.m and the position between the piezoelectric wafer and the electrode plate is not generated under the pushing of 50g of transverse force), the parallelism of 0.02mm (the maximum allowable error value of the upper surface relative to the lower surface in parallel, the higher the parallelism, the higher the limit stress of the wafer is), and the BTS wafer has particularly excellent high-temperature piezoelectric performance and temperature stability, so that the piezoelectric vibration sensor can resist the high temperature of 700 ℃.

Furthermore, the signal generation portion is adorned in the base shell upside down (the signal generation portion of flip-chip, ceramic nut end cup joints in airtight inner chamber downwards to weld the top cap on the base shell, the connector includes metal contact pin, is connected with the metal signal line between quality piece and the metal contact pin.

Preferably, the piezoelectric wafers are annular, a plurality of piezoelectric wafers are sleeved on the ceramic tube in parallel, and the directions of the electrodes of the two adjacent piezoelectric wafers are opposite, namely the piezoelectric wafers are overlapped together in parallel in a mode that the negative electrodes are opposite and the positive electrodes are opposite, so that the sensitivity of the piezoelectric vibration sensor is improved;

preferably, each electrode plate comprises a plurality of electrode rings, adjacent electrode rings are connected in series through connecting wires, and the electrode rings are used for being clamped between the piezoelectric wafers or between the piezoelectric wafers and the mass block/top cover;

the electrode ring of one path of electrode plate is inserted between the cathodes of the piezoelectric wafers, the electrode ring of the other path of electrode plate is inserted between the anodes of the piezoelectric wafers, and the piezoelectric wafers and the two paths of electrode plates form a crystal group.

Preferably, the starting position of one path of electrode plate is arranged between the bottommost laminated wafer and the top cover, the tail end of the electrode plate is positioned between the two uppermost piezoelectric wafers, the starting position of the other path of electrode plate is arranged between the two bottommost piezoelectric wafers, the tail end of the electrode plate is arranged between the piezoelectric wafers on the uppermost layer and the mass block, the number of the piezoelectric wafers is odd, and the bottom size of the mass block is preferably the same as the outer diameter of the piezoelectric wafers;

preferably, the electrode sheet is made of a nickel metal sheet.

Preferably, the electrode plate can be manufactured by a laser marking machine, the inner diameter and the outer diameter of the electrode ring are kept to be the same as those of the piezoelectric wafer, the inner diameter of the electrode ring is slightly larger than the diameter of the ceramic tube, the length of the connecting wire can be determined according to the thickness of the piezoelectric wafer, and when the thickness of the piezoelectric wafer is 0.7mm, the length of the connecting wire is preferably 3mm and the width of the connecting wire is 2 mm.

Preferably, the connector also comprises a connector ceramic tube and a metal shell, and the metal pin, the connector ceramic tube and the metal shell are fixed together by a brazing technology;

the metal contact pin is sleeved into the connector ceramic tube in an interference fit manner, the right inner diameter of the metal shell is slightly smaller than the outer diameter of the connector ceramic tube, the connector ceramic tube is sleeved into the metal shell from the left side until the connector ceramic tube contacts the right inner diameter of the metal shell, and the metal contact pin, the connector ceramic tube and the metal shell are fixed in a brazing manner;

the connector is welded on the mounting port B of the base shell.

Preferably, the metal shell and the metal pin are made of kovar alloy (4J33), the ceramic tube, the connector ceramic tube and the ceramic nut are made of alumina ceramic, the alumina purity is preferably 99.5%, a gold film with the thickness of 100nm is electroplated on the surface of the metal pin, and the metal signal wire is welded on the metal pin.

The metal shell and the metal contact pin in the connector are made of kovar alloy, the ceramic tube of the connector is made of alumina ceramic with the purity of 99.5%, and the thermal expansion coefficients of the kovar alloy and the alumina ceramic are basically consistent, so that the air tightness of the sensor at high temperature can be ensured.

Preferably, the mass block is made of Inconel718 alloy, and a platinum film with the thickness of 200-300nm is evaporated on the surface of the electrode plate and the surface of the mass block in contact with the electrode plate;

the Inconel718 alloy can ensure that the elastic modulus of the structural rigidity of the sensor at high temperature is still in a linear range, and compared with other high-temperature materials, the Inconel718 alloy has higher density and high stability, and can effectively improve the mass of a mass block, thereby improving the sensitivity and stability of the sensor; a layer of platinum film evaporated on the bottom surface can ensure excellent electric contact during signal transmission of the sensor.

Preferably, the base shell and the top cover are both made of Inconel601 alloy. The Inconel601 alloy has excellent corrosion resistance at high temperature (less than or equal to 1000 ℃), can ensure the air tightness of the sensor at high temperature and the anti-interference capability in the signal transmission process, and prolongs the service life of the sensor.

Preferably, the upper end of the mass block is provided with a connecting hole, the diameter of the connecting hole is matched with the outer diameter of the metal signal wire, and the metal signal wire is inserted into the connecting hole and is welded and connected;

preferably, the diameter of the connecting hole is 1mm, the depth is 4mm, and the outer diameter of the metal signal wire is 1 mm.

One end of a metal signal wire is welded on the mass block, the other end of the metal signal wire is welded on the metal contact pin, the metal signal wire is positioned in a closed inner cavity in the sensor and is welded on the mass block to serve as a signal output wire of the sensor, and the metal signal wire is in a fixed state after being assembled, so that the micro-disturbance generated in the signal transmission process is greatly reduced.

Preferably, the central column is provided with an external thread, the ceramic tube is provided with an internal thread matched with the external thread of the central column, and a high-temperature insulating glue (preferably double-bond chemical DB5012) is filled between the central column and the ceramic tube, and the application range of the high-temperature insulating glue exceeds 1500 ℃;

the ceramic nut is provided with internal threads, after the signal generating part is assembled, the upper end of the central column is higher than the upper end of the ceramic tube, the ceramic nut is screwed into the central column, and the pre-tightening torque of the ceramic nut is 0.35-0.5 N.m;

the ceramic nut with the pre-tightening effect is connected with the central column and the metal mass block together through threads and high-temperature insulating glue under the pre-tightening torque of 0.35-0.5 N.m (the mass block and the ceramic tube are nested without being fixed by glue), so that the bolt looseness of the sensor under the high-temperature and strong-vibration effects is prevented, the ceramic tube with the insulating effect is fixed, the transverse signal interference of the sensor in the vibration process is avoided, and the use reliability and precision of a sensing device are effectively improved.

Preferably, a counter bore is arranged at one section of the mass block, which is in contact with the ceramic nut, and the ceramic nut is positioned in the counter bore after the assembly is completed.

The assembling method of the high-temperature vibration acceleration sensor comprises the following steps of:

(1) pouring diluted high-temperature insulating glue into a ceramic tube with internal threads, and screwing the ceramic tube into the central column of the top cover in a rotating manner, wherein the ceramic tube is in close contact with the top cover without a gap;

the diluted high-temperature insulating glue is preferably used after 1.5-2 g of the high-temperature insulating glue and 1mL of diluent are diluted.

(2) Assembling a crystal group: plating a 200-plus-300 nm thick platinum film on the upper and lower surfaces of a piezoelectric wafer, wherein the platinum film can ensure excellent electrical contact between the wafer and an electrode at high temperature, the piezoelectric wafers are overlapped in parallel in a mode that a negative electrode is opposite and a positive electrode is opposite, electrode plates are added between the piezoelectric wafers, connecting wires of two electrode plates are respectively folded, an electrode ring of one electrode plate is respectively inserted between the positive electrodes of the piezoelectric wafers, the electrode plate is tightly contacted with a top cover and is insulated with a mass block, the starting position of the electrode plate is arranged between the bottommost laminated wafer and the top cover, and the tail end of the electrode plate is positioned between the two uppermost laminated wafers; the electrode rings of the other electrode plate are respectively inserted between the cathodes of the piezoelectric wafers, the initial position of the electrode rings is arranged between the two piezoelectric wafers at the bottom layer, the tail end of the electrode rings is arranged between the piezoelectric wafers at the top layer and the mass block, the electrode plates are tightly contacted with the mass block and are insulated with the top cover base, the piezoelectric wafers and the two electrode plates form a crystal group, and as shown in a crystal group shown in fig. 4(a), the two electrode plates are inserted into the piezoelectric wafers which are oppositely superposed together in the same polarity in a crossed manner;

the electrode plate is integral, when the electrode plate is assembled, after a first electrode ring at one end is inserted into a corresponding position, a connecting wire can be bent directly, after a second electrode ring adjacent to the first electrode ring is inserted into the corresponding position, the connecting wire is bent reversely, a third electrode ring is inserted into a corresponding position, the process is repeated until the whole electrode ring is inserted, and welding spots in the sensor assembling process are effectively reduced;

(3) sleeving a crystal group and a mass block on a ceramic tube in sequence, pouring high-temperature insulating glue into threads of a ceramic nut, screwing the ceramic nut into a central column, tightly combining a top cover, the crystal group and the mass block together, putting the fixed top cover, the crystal group and the mass block into a drying box with the temperature of 150-180 ℃ for 12-18 hours, and completing the curing of the high-temperature insulating glue until the signal generating part is assembled;

(4) fixing the metal pin, the connector ceramic tube and the metal shell in a high-temperature vacuum brazing furnace by using a clamp, wherein the vacuum degree in the furnace is less than 10^-5Pa, controlling the temperature at 800-900 ℃, keeping the temperature for 5-6 hours to melt the high-temperature brazing filler metal, infiltrating the brazing filler metal into gaps among the ceramic tube of the connector, the metal contact pins and the metal shell through capillary action, and finishing the installation of the connector after annealing;

(5) placing the cured signal generating part, the base shell and the connector into an inert gas atmosphere box, wherein the gas pressure in the atmosphere box is slightly greater than one atmosphere, one end of a metal signal wire is inserted into the metal contact pin and fixed by spot welding, the other end of the metal signal wire is inserted into a connecting hole reserved in the mass block and well welded, and the signal generating part and the connector are respectively placed at a mounting opening A and a mounting opening B and are fixed by a clamp;

(6) welding the signal generating part, the base shell and the connector together by laser welding to enable the signal generating part, the base shell and the connector to be in close contact without a gap, and obtaining a sensor;

(7) and (4) putting the welded sensor into a high-temperature box for annealing treatment, and eliminating stress residues among devices.

When the high-temperature vibration acceleration sensor works, a screw is utilized to fix the sensor on the surface of a machine to be detected through the circular-arc-shaped jaws at two ends of the outer shell of the outer base by the aid of the screw, so that the sensor is tightly combined with the surface of the machine, vibration is generated when the machine works, periodic force generated by the vibration is transmitted to the sensor through the surface of the machine, a mass block in the sensor generates inertial force, accordingly, the upper surface and the lower surface of a piezoelectric wafer are pressed to generate charges with opposite signs and equal numerical values, the charges are transmitted to a connector through a signal wire, the connector transmits the charge signals to a charge amplifier through a high-temperature hard cable, the charge amplifier converts the charge signals into voltage signals, and the voltage signals are transmitted to a data acquisition card and.

The invention can manufacture the high-temperature vibration sensor with high sensitivity, high stability, wide frequency response, low temperature drift, low crosstalk and other performances, provides excellent front-section signal acquisition for the health early warning systems of aircraft engines, propulsion systems of intelligent ships and the like, and is convenient to produce and install, simple in process and convenient for large-scale production.

In the present invention, the details are not described in detail, and the present invention can be carried out by using the prior art.

The invention has the beneficial effects that:

1) the sensor has excellent performance at high temperature, the temperature drift is less than 5%, the linearity at 700 ℃ is less than 1%, the impact resistance of the sensor reaches 50g at high temperature due to simple and stable structure, and the sensor can work for a long time in an environment at 650 ℃ and can be in short-term service in an environment at 700 ℃ by adopting a (ZXl/45 ℃) cut type of BTS crystal which has stable electrical property and higher sensitivity at high temperature as a piezoelectric sensitive element.

2) The invention adopts a mode of combining a plurality of piezoelectric wafers in parallel, saves the internal space of the sensor and effectively improves the sensitivity of the sensor.

3) The Inconel601 alloy is adopted for the base shell and the top cover, has excellent corrosion resistance at high temperature, can ensure the air tightness of the sensor and the anti-interference capability in the signal transmission process at high temperature, and greatly prolongs the service life of the sensor.

4) The mass block of the invention adopts Inconel718 alloy, and the alloy can ensure that the elastic modulus of the structural rigidity of the sensor is still in a linear range at high temperature; compared with other high-temperature materials, the mass block has higher density, and can effectively improve the weight of the mass block, thereby improving the sensitivity of the sensor; a layer of platinum vapor-deposited on the bottom surface can ensure excellent electric contact during signal transmission of the sensor.

5) Aiming at the sealing performance and stability of the sensor, the invention designs and selects the 99.5 percent alumina ceramic tube with high temperature resistance and stable property, the central column, the ceramic tube and the mass block are solidified by matching with high-temperature insulating glue, and the device is packaged by utilizing laser and an atmosphere box, thereby ensuring the beauty of the welding line of the sensor and avoiding cracking; the invention has simple structure, strong stability, high feasibility, low cost and convenient production, thereby achieving the purpose of industrialization.

6) The connector is designed, the kovar alloy (4J33) which is matched with the thermal expansion coefficient of the ceramic is selected as the shell and the contact pin of the connector, and the kovar alloy and the contact pin are tightly combined together in a high-temperature vacuum brazing mode, so that the air tightness of the sensor at high temperature is ensured, and the installation difficulty of the sensor is reduced.

7) One end of a metal signal wire is inserted into the mass block, and the other end of the metal signal wire is welded on the metal contact pin, so that the signal transmission flow of the high-temperature sensor is simplified, and the stability in the signal transmission process is improved;

the invention adopts a flip assembly mode, namely the center post which is connected with the piezoelectric wafer and the mass block in series is positioned at the top of the sensor, thereby greatly reducing the interference of the deformation of the base at the bottom of the sensor to the sensor signal caused by the large-range transverse vibration of the mechanical surface during the assembly of the sensor and the measured, and improving the frequency response range of the sensor.

8) According to the invention, the sensor is mounted on the surface of the measured machine in a mode of fixing two ends, and compared with the bottom single-hole thread mounting, the deformation quantity in the sensor assembly engineering is reduced, the contact rigidity of the sensor and the measured contact surface is improved, and the risk of sensor failure caused by improper assembly is reduced.

Drawings

FIG. 1 is a schematic exterior view of a high temperature vibration acceleration sensor of the present invention after assembly;

FIG. 2 is an assembly schematic of the high temperature vibration acceleration sensor of the present invention;

FIG. 3 is an assembled view of the signal generating section of the present invention;

FIG. 4(a) is a schematic diagram of a boule structure according to the present invention;

FIG. 4(b) is a schematic diagram of a piezoelectric wafer in a group structure;

FIG. 4(c) is a schematic structural diagram of an electrode plate in a crystal group structure;

FIG. 5 is a schematic diagram of a mass structure according to the present invention;

FIG. 6 is an assembled view of the connector of the present invention;

FIG. 7 is a schematic structural view of a base housing of the present invention;

FIG. 8 is a cut-out schematic of a piezoelectric crystal of the present invention;

FIG. 9 is a schematic diagram of the performance of one embodiment of the present invention at elevated temperatures;

FIG. 10 is a schematic view of the operation of the sensor of the present invention at high temperatures (600 ℃ and 650 ℃);

the device comprises a signal generating part, a base shell, a mounting port A, a mounting port B, a circular arc jaw, a connector, a 4-ceramic nut, a 5-mass block, a 5.1-connecting hole, a counter bore, a 6-crystal group, a top cover, an 8-ceramic tube, a 9-metal shell, a 10-connector ceramic tube, a 11-metal contact pin, a 12-piezoelectric wafer, a 13-central column, a 14-electrode plate, a 15-metal signal wire, a 16-electrode ring and a 17-connecting wire, wherein the signal generating part comprises a signal generating part, the base shell, the mounting port A, the mounting port B, the circular arc jaw, the 3-connector, the ceramic nut, the.

The specific implementation mode is as follows:

in order to make the technical problems, technical solutions and advantages of the present invention more apparent, the following detailed description is given with reference to the accompanying drawings and specific examples, but not limited thereto, and the present invention is not described in detail and is in accordance with the conventional techniques in the art.