CN112834069B - Ni-Cr alloy temperature sensor based on magnetostrictive torsional wave - Google Patents

Abstract

The invention relates to a Ni-Cr alloy temperature sensor based on magnetostrictive torsional waves. The sensor comprises a cylindrical shell, a measuring rod, a Fe-Ga wire, a chromium-nickel alloy wire, a pulse signal generating module, a control sampling module, a ceramic sleeve, a damper, a permanent magnet and a detection coil; the right end of the measuring rod is closed, one end of the chrome-nickel alloy wire is fixed at the center of the inner wall of the right end of the measuring rod, the other end of the chrome-nickel alloy wire penetrates through the measuring rod and enters the shell, the right part of the chrome-nickel alloy wire in the ceramic sleeve is connected with the right end of the Fe-Ga wire, and the left end of the Fe-Ga wire penetrates through the inside of the ceramic sleeve and penetrates through the damper and is fixed at the center of the inner wall of the left end of the shell; the measuring rod is in the shape of a linear measuring rod and a plane disc-shaped measuring rod. The invention can effectively reduce the noise signal influence caused by high voltage, high frequency and vibration in ultrasonic temperature measurement.

Description

A Ni-Cr Alloy Temperature Sensor Based on Magnetostrictive Torsional Wave

technical field

The invention combines the magnetostrictive material with the sensitive element material and applies it to the field of temperature sensors, mainly related to the Fe-Ga filamentary material with magnetostrictive effect and the nickel-chromium alloy wire as the sensitive element material, which can be applied to the temperature sensor. Measurement to realize real-time monitoring of temperature.

Background technique

Magnetostrictive temperature sensors have the potential to provide reliable temperature measurement for many applications, including glass and low-melting point metal smelting, process industries, nuclear power plants, etc. where temperature monitoring is critical, enabling real-time temperature monitoring and temperature monitoring of the entire industrial process and The spatial temperature distribution is displayed. There are many problems in thermocouples, thermal resistances and non-contact temperature measurement commonly used in industry. For example, thermocouples and thermal resistance temperature sensors are often affected by temperature drift during long-term work, and the output signal voltage amplitude is small and susceptible to Electromagnetic interference, long-distance transmission difficulties, and the ability of a sensor to only measure the temperature of one location; non-contact temperature measurement methods include various optical temperature measurement methods and radiation pyrometers, such as infrared temperature measurement, fiber optic black body cavity temperature measurement and other technologies, and other The temperature measuring element does not need to be in contact with the measured medium, and does not affect the temperature field during combustion, but the smoke generated during the combustion of the propellant pollutes the photodetector on the one hand, and on the other hand the test environment has a certain influence on the emissivity, resulting in temperature measurement data and Theoretical calculations are very different; although the radiation pyrometer can keep a long distance from the high temperature area, there is no upper limit of temperature measurement in theory, but because the emissivity of the target system is difficult to determine, the measurement accuracy is greatly affected by the emissivity, composition, concentration, and environmental field , there are many uncertain factors, so the reliability of the test data is low. However, in some industrial applications, it is necessary to monitor the temperature in high-temperature and ultra-high-temperature environments for a long time, such as ammunition explosions, nuclear experiments, and aerospace engine operations in the military field, and in the cylinders of nuclear energy pressurized water reactors, diesel engines, and steam turbines in the energy field. In superchargers and reheaters, in large-scale equipment such as reactors in petroleum, chemical and other fields, and in the measurement of temperature in other material synthesis and process monitoring, etc., it is inevitable that there will be long-term ultra-high temperature in-situ testing. Fluid temperature measurement. In addition, the failure of junctions in thermocouples in high temperature and high vibration environments is also very costly, especially when using devices such as compensating wires.

With the continuous development of modern industrialization, guided wave temperature measurement technology is widely used in industry, and the requirements for guided wave signal quality are increasing day by day. Guided wave temperature measurement is mainly based on ultrasonic waves and low-frequency sound waves. Ultrasonic waves have good directivity, but attenuate quickly, and are mostly used for short-distance temperature measurement; low-frequency sound waves can travel longer distances, and have been used for indoor temperature and furnace flames. For the measurement of temperature and lake water temperature, the research on using low-frequency sound waves to measure air temperature is mainly focused on two-dimensional tomography research, and the accuracy of single-path temperature measurement needs to be improved. The main problem of low-frequency sound wave temperature measurement is that the time resolution is too low due to too low sampling frequency, and the change of sound wave propagation time caused by temperature cannot be detected; the distance measured between two microphones is directly regarded as the actual sound wave propagation path length and the time of the system itself is ignored. Delay, resulting in inaccurate sound velocity measurement. In terms of ultrasonic temperature measurement sensors, according to the principle division, it mainly focuses on the pulse reflection method, resonance method and pulse penetration method. Among them, the resonance method has high measurement accuracy but takes a long time to measure. The penetration method requires two ultrasonic probes and cannot be spontaneously collected. The ultrasonic echo signal analysis of the pulse reflection method is difficult, and the signal is small and susceptible to interference. There are still deficiencies in practical applications. Industrial applications are unreliable and difficult for large-scale commercial production. The disadvantages of traditional sensitive element materials such as thorium-tungsten alloy, tungsten-rhenium alloy, sapphire, and stainless steel as waveguides are mainly reflected in: (1) Except for a few expensive materials, most waveguide materials are easily oxidized at high temperatures above 800 °C; (2) ) The data processing and result display equipment are complex and costly; (3) rely on ultrasonic transducers, and the hysteresis characteristics of ultrasonic transducers and their susceptibility to temperature limit the measurement accuracy; When propagating in a uniform cylindrical waveguide rod, the ultrasonic waves are reflected multiple times at the boundary and etching of the waveguide rod, resulting in geometric dispersion and complex interference phenomena in the waveguide rod, which causes great difficulty in signal processing; (5) Ultrasonic waves The higher the frequency, the easier it is to attenuate, which is not conducive to expanding the range. The disadvantages of using magnetostrictive materials directly as sensitive element materials are mainly reflected in (1) the Curie temperature of magnetostrictive materials is only 980°C, which limits the temperature measurement range; (2) when it exceeds 600°C, The signal attenuation is serious and the signal-to-noise ratio becomes extremely poor, so that the magnetostrictive material is used as a waveguide, and the measurement range is only room temperature-600°C; (3) The magnetostrictive material expands severely when heated, resulting in obvious actual errors.

"An Absolute Ultrasonic Magnetostrictive Temperature Sensor" published by me before proposed a temperature sensor structure using magnetostrictive materials as the core, but there are still deficiencies in the measurement and reliability of higher temperatures: (1) The electrical insulation of the wire inside the measuring rod is difficult to manufacture, and insulating materials such as silicone glass fiber tubes are difficult to achieve applications above 600°C, and the complex structures of insulating materials such as ceramic glass are difficult to process, and their use in vibration environments is limited; (2) used in patents The linear expansion coefficient of Fe-Ga and other magnetostrictive materials is relatively large, so the mechanical movement structure of the constant elastic force device introduced for this reduces the reliability of the sensor; , The permanent magnet has the risk of demagnetization under high temperature and vibration environment, and it is difficult to guarantee the service life of the sensor. Therefore, there is a need for an alternative temperature sensor that has a simple excitation method, is more reliable at high temperatures, and can adapt to complex and harsh working conditions.

Invention content:

In order to realize the accurate measurement of real-time temperature by the temperature sensor, the present invention designs a Ni-Cr alloy temperature sensor based on the magnetostrictive torsional wave, aiming at the problems of poor quality of the ultrasonic temperature measurement signal and the low Curie temperature and easy oxidation of the sensitive element material. sensor. The sensor combines the magnetostrictive material with the sensitive element material. The chromium-nickel alloy wire and the Fe-Ga wire are physically connected by laser welding instead of the coupling agent. The connection is a whole wire, and the laser welding is in the shape of a drop. It plays the role of energy-gathering amplification, so that the torsional wave signal generated by the Weidmann effect can be effectively transmitted at the welding place between the chromium-nickel alloy wire and the Fe-Ga wire; at the same time, the detection coil is fixed at the right end of the Fe-Ga wire close to the chromium-nickel wire The position of the alloy wire, the waveform before the torsional wave is transmitted from the Fe-Ga wire into the Cr-Ni alloy wire and the waveform just transmitted from the Cr-Ni alloy wire to the Fe-Ga wire are detected by the Weidmann inverse effect, so that the difference between the two waveforms The time interval between is the time for the torsional wave to propagate in the chromium-nickel alloy wire, making full use of the Weidmann effect and Weidmann inverse effect of the Fe-Ga wire as a magnetostrictive material, and simultaneously plays the role of signal generation and detection .

Technical scheme of the present invention is:

A Ni-Cr alloy temperature sensor based on magnetostrictive torsional waves, the sensor includes a cylindrical shell, a measuring rod, Fe-Ga wire, chromium-nickel alloy wire, a pulse signal generation module, a control sampling module, a ceramic sleeve Tubes, dampers, permanent magnets and detection coils;

Among them, there are grooves in the center of the left and right inner walls of the horizontal housing, and the two ends of the ceramic sleeve are respectively fixed on the two grooves; the left side of the ceramic sleeve is provided with damping; There is also a through hole in the center of the right side, and a measuring rod is fixed outside the through hole; the housing and the measuring rod have the same axis; the right end of the measuring rod is closed, and one end of the chromium-nickel alloy wire is fixed Pass through the measuring rod and enter the housing. The right part of the ceramic sleeve is connected to the right end of the Fe-Ga wire. The left end of the Fe-Ga wire passes through the ceramic sleeve and passes through the damper, and is fixed at the center of the inner wall of the left end of the housing. The connection between the chromium-nickel alloy wire and the Fe-Ga wire is drop-shaped; the ceramic casing at the right end of the Fe-Ga wire is covered with a detection coil; the outside of the ceramic casing between the damping and the detection coil is also covered with a ring-shaped permanent magnet ;

The upper part and the lower part of the housing are respectively provided with a pulse signal generating module and a control sampling module, wherein the pulse signal generating module is connected to both ends of the Fe-Ga wire through wires; the detection coil is respectively connected to both ends of the control sampling module;

The distance between the right end of the detection coil and the drop-shaped connection is 1-5mm;

The distance between the left end of the detection coil and the annular permanent magnet is 150-200mm;

The measuring rod is a straight measuring rod or a plane measuring rod.

The linear measuring rod is a straight stainless steel tube;

The shell material of the planar measuring rod is a stainless steel spiral tube with a circular corrugated structure, and the shape is a planar vortex line;

The materials of the measuring rod and the housing are all non-ferromagnetic stainless steel, with a temperature resistance of 1400°C;

The ceramic bushing is an alumina ceramic bushing;

The composition of the chromium-nickel alloy wire is Cr ₂₀ Ni ₈₀ ;

The composition of the Fe-Ga wire is Fe ₈₃ Ga ₁₇ ;

The material of the annular permanent magnet is samarium cobalt YX28, and the inner side is insulated;

The damping is mesoporous silica airgel;

The drop-shaped laser welding coupling part has an elliptical cross-section, a length of 2-4 mm, and a maximum diameter of 1.5-2 mm;

The ratio of the length of the Fe-Ga wire to the chromium-nickel alloy wire is 0.4-0.67, and the ratio of the diameter is 1.2-1.5,

The length of the cylindrical shell is 1-1.1 times that of the Fe-Ga wire;

The length of the ceramic sleeve is 1-1.1 times the length of the cylindrical shell;

The lengths of the measuring rods in the different interval temperature measuring units are the same or different, and the length ranges from 450 to 650 mm;

The length of the circular permanent magnet is 2-5mm;

The damping is 15-30mm in length and 5-10mm in diameter;

The damping is 50-150mm according to the distance from the left end of the permanent magnet;

The detection coil is a hollow cylinder wound by an enameled wire with 300-1500 turns and a length of 10-20mm.

Substantive features of the present invention are:

The Ni-Cr alloy temperature sensor based on the magnetostrictive torsional wave consists of a cylindrical shell, Fe-Ga wire, chromium-nickel alloy wire, permanent magnet, measuring rod, detection coil, ceramic sleeve, control sampling module, pulse signal The generating module consists of eight parts, which can accurately measure the temperature in the measured area. The ceramic sleeve is made of alumina ceramic material, and the shell is used to fix and protect the internal components; the circular permanent magnet is used to generate an axial magnetic field. Under the combined action of the circumferential magnetic field generated by the unidirectional pulse excitation signal, the Fe-Ga An instantaneous torsional wave is formed inside the wire; the torsional wave signal in the chromium-nickel alloy wire is transmitted from the Fe-Ga wire to the chromium-nickel alloy wire, and the signal is reflected at the end face of the chromium-nickel alloy wire; by determining the distance between the signal generation wave and the reflected wave The time delay value can be used to accurately measure the temperature; the Curie temperature of chromium-nickel alloy wire is as high as 1400 ℃ and above, and the working temperature reaches 1200 ℃, and the thermal expansion is weak at high temperature, which can expand the measurement range to 1000 ℃; the torsional wave speed is faster than the longitudinal wave Slow, no dispersion phenomenon under high temperature and high frequency, high sensitivity and easy detection; the acquisition card collects waveform signals and displays them on the computer.

The beneficial effects of the present invention are:

1. Using the magnetostrictive effect of Fe-Ga wire, the circumferential magnetic field generated under the excitation pulse is combined with the axial magnetic field generated by the permanent magnet to generate a torsional wave signal and propagate it. The sensor effectively reduces the influence of noise signals caused by high voltage, high frequency and vibration in ultrasonic temperature measurement.

2. The wave speed of torsional wave T(0,1) is slower than that of longitudinal wave L(0,1), and there is no dispersion phenomenon at high temperature and high frequency, with high sensitivity and easier detection. The axisymmetric torsional mode is a commonly used detection mode in ultrasonic guided waves, especially the T(0,1) mode excited in the waveguide screw model. The wave packet structure of the T(0,1) mode is simple, and its incident signal can maintain the signal waveform during the propagation process, and the propagation distance is longer and the attenuation is small; the propagation speed of the guided wave of this mode is within a certain frequency range It is basically not affected by frequency changes, that is, it has good non-dispersive characteristics; there is only circumferential vibration displacement, no radial displacement, and less energy leakage during guided wave propagation, which is easy to detect.

3. Using the fixed length d of the sensitive element material, convert the time delay value t of the two reflections into the torsional wave propagating speed c=2d/t in the sensitive element material, so as to determine the temperature at this time. The etching of the nodes is avoided, the influence of vibration on the material is reduced, and the service life of the material is prolonged.

4. The Curie temperature of chromium-nickel alloy wire is as high as 1400°C and above, and the working temperature reaches 1200°C, and its thermal expansion is weak at high temperature, which can expand the measurement range to above 1000°C and effectively reduce the error, improving the sensor's high temperature performance. work reliability in the environment.

5. Placing the permanent magnets and wires inside the shell away from the high-temperature environment greatly reduces the degaussing phenomenon of the permanent magnets and the dependence on the high-temperature-resistant insulating materials of the electrical connection wires, effectively reducing the production cost of the sensor.

6. Based on the above improvements, after a large number of experiments, the configuration of each part was optimized, and a Ni-Cr alloy temperature sensor based on the magnetostrictive torsional wave was designed. The experiment obtained a 600-turn detection coil, and the excitation pulse was 30V in amplitude and 1200Hz in frequency. The output voltage produced by the square pulse wave with a pulse width of 5 microseconds is the largest, and the sound velocity and temperature fitting curve T=

7601.974-2.44618*v, can be used as the basis for detecting temperature.

7. Compared with the pulse reflection method guided wave temperature measurement device, the pulse voltage of 50-500V is applied to the ultrasonic transducer (due to the different types of piezoelectric probes and coupling conditions, the applied voltage will vary greatly) and the 80d B gain (amplification) needs to be passed. 10000 times) to obtain an output of about 1V, this design applies 30V to both ends of the Fe-Ga wire (length 300mm, different lengths lead to different resistances of Fe-Ga wire), and the maximum 19.2mV can be directly obtained at both ends of the detection coil without an amplifier Minimum voltage output of 4.96m V. This design has a strong original output signal (without the amplifier), and the transmitter can be directly installed at the remote control end through the connecting cable, further improving reliability and maintainability, and can be applied to high temperature, high pressure, closed environment and strong Under complex and harsh working conditions such as vibration.

Description of drawings

Fig. 1 is the structure diagram of the Ni-Cr alloy temperature sensor based on the magnetostrictive torsional wave of the present invention;

Fig. 2 is the relation figure of incident wave and reflected wave and transmitted wave of the present invention;

Fig. 3 is the Ni-Cr alloy temperature sensor sound wave propagation schematic diagram based on magnetostrictive torsional wave of the present invention;

Fig. 4 is a schematic diagram of a planar sensor;

Fig. 5 is the Ni-Cr alloy temperature sensor based on the magnetostrictive torsional wave of the present invention at 20°C normal temperature delay data waveform;

Fig. 6 is the delay data waveform diagram of the Ni-Cr alloy temperature sensor based on the magnetostrictive torsional wave from room temperature to 1000°C in the present invention;

Fig. 7 is the measured output temperature curve;

Fig. 8 is a fitting curve of torsional wave velocity and temperature.

Among them, 1 shell, 2 measuring rod, 3 Fe-Ga wire, 4 chromium-nickel alloy wire, 5 pulse signal generating module, 6 control sampling module, 7 ceramic bushing, 8 damping, 9 permanent magnet, 10 detection coil;

Detailed ways

In the present invention, the magnetostrictive torsional wave emitted in the Fe-Ga wire is propagated in the nickel-chromium alloy wire, the transmission time of the torsional wave is determined by monitoring the torsional wave signal transmission waveform, and then the influence of the torsional wave velocity with temperature changes is fully combined. The magnetostrictive material Fe-Ga alloy wire has a simple excitation method and the original output signal is strong, and the sensitive element nickel-chromium alloy wire has good oxidation resistance and high Curie temperature. Structurally, the chromium-nickel alloy wire and Fe-Ga wire are physically connected by laser welding instead of the coupling agent, and the connection is a whole wire, and the laser welding is in the shape of a water drop, which plays a role in gathering energy and amplifying the energy passing through Wei De The torsional wave signal generated by the Mann effect can be effectively transmitted at the welding place between the Cr-Ni alloy wire and the Fe-Ga wire; at the same time, the detection coil is fixed on the Fe-Ga wire close to the Cr-Ni alloy wire, through the Weidmann inverse effect Detect the waveform before the torsional wave is transmitted from the Fe-Ga wire into the Inconel wire and the waveform just transmitted from the Inconel wire to the Fe-Ga wire, so that the time interval between the two waveforms is the torsional wave in the Inconel wire. The propagation time in the wire makes full use of the Weidmann effect and Weidmann inverse effect of the Fe-Ga wire as a magnetostrictive material, and plays the role of signal generation and detection at the same time. The temperature sensor uses Fe-Ga wire and chrome-nickel alloy wire as the core components. One end of the Fe-Ga wire is fixed to the left end of the ceramic sleeve through the damper, and the other end is connected to the chrome-nickel alloy. The Fe-Ga wire is connected to the chrome-nickel alloy The laser welding coupling is used between the wires. When the circumferential excitation magnetic field generated by the pulse current and the axial bias magnetic field generated by the permanent magnet produce the Weidmann effect, since the instantaneous circumferential excitation magnetic field is applied, the Fe-Ga wire will Instantaneous deformation is generated, and then torsional waves propagating to both ends of the Fe-Ga wire are generated; in addition, the chromium-nickel alloy is coupled with the Fe-Ga wire, so that part of the torsional wave is reflected on the end surface, and the other part is projected and continues along the chromium-nickel wire. The alloy wire propagates and reflects again after reaching the end face of the chromium-nickel alloy wire; finally, the detection coil is used to detect the torsional wave signal, and the coil fixes the end of the Fe-Ga wire connected to the chromium-nickel alloy wire, which is connected to the control sampling module; the torsional wave velocity is relatively high. The longitudinal wave is slow, and it is not easy to disperse under high temperature and high frequency conditions, which can increase the sensitivity of the detection signal and improve the measurement accuracy. In the device of the present invention, the Fe-Ga wire is coupled with the chromium-nickel alloy. When the torsional wave propagates to the coupling interface, a part of the torsional wave is reflected, and the other part of the torsional wave passes through the interface and propagates to the chromium-nickel alloy wire, so that the torsional wave energy continues Propagated in the chromium-nickel alloy wire, by recording the delay data between waveforms, the delay data graph at different temperatures can be obtained, so as to obtain the variation curve of the torsional wave propagation speed with temperature. The invention effectively solves the shortcomings of traditional ultrasonic temperature sensors such as relying on ultrasonic transducers, weak original signals, prone to vibration after repeated etching, and easy oxidation of sensitive element materials; compared with magnetostrictive materials directly used as sensitive element materials, nickel The high Curie temperature of the chromium alloy extends the range of the temperature sensor. Experimental results show that when the present invention is used for temperature measurement, 30V is applied to both ends of the Fe-Ga wire (length 300mm), and a voltage output of maximum 19.2mV and minimum 4.96mV can be directly obtained at both ends of the detection coil without an amplifier.

The invention is described in further detail below in conjunction with the drawings. This embodiment is only a specific description of the invention and is not considered as limiting the scope of protection.

The Ni-Cr alloy temperature sensor based on magnetostrictive torsional wave of the present invention is as shown in Figure 1, and the main part of this sensor comprises cylindrical housing 1, measuring rod 2, Fe-Ga wire 3, chrome-nickel Alloy wire 4, pulse signal generating module 5, control sampling module 6, ceramic sleeve 7, damping 8, permanent magnet 9, and detection coil 10;

Wherein, there is a groove in the center of the inner wall of the left and right sides of the horizontal housing 1, and the two ends of the ceramic sleeve 7 are respectively fixed on the two grooves (there are through holes on the side walls of the two ends of the ceramic sleeve 7). , to facilitate wire access); the inside of the left side of the ceramic sleeve 7 is provided with a damping 8; the center of the right side of the housing 1 also has a through hole, and the outside of the through hole is fixed (welded) with a measuring rod 2; the housing 1 The same axis as the measuring rod 2; the right end of the measuring rod 2 is closed, one end of the chromium-nickel alloy wire 4 is fixed at the center of the inner wall of the right end of the measuring rod 2, and the other end passes through the measuring rod 2 and enters the housing 1, and is inside the ceramic sleeve 7 The right part is connected with the right end of the Fe-Ga wire 3, and the left end of the Fe-Ga wire 3 passes through the inside of the ceramic sleeve 7 and passes through the damper 8, and is fixed on the center of the left end inner wall of the housing 1; the chromium-nickel alloy wire 4 and The Fe-Ga wire 3 is connected by laser welding, and the joint is in the shape of a drop; the right end of the Fe-Ga wire 3 is covered with a detection coil 10; The magnet 9, the annular permanent magnet 9 on the ceramic sleeve 7 must be outside the detection blind zone of the detection coil 10;

The upper part and the lower part of the housing 1 are respectively provided with a pulse signal generating module 5 and a control sampling module 6, wherein the pulse signal generating module 5 is connected to both ends of the Fe-Ga wire 3 through wires; end connected;

The axes of the housing 1, the measuring rod 2, the Fe-Ga wire 3, the chromium-nickel alloy wire 4, and the ceramic sleeve 7 are all the same;

The cylindrical shell 1 has an inner diameter of 60mm, a length of 300mm, and a wall thickness of 2mm, and is made of stainless steel with a material grade of 430;

The measuring rod 2 is a straight measuring rod or a planar measuring rod. Among them, the measuring rod 2 can be used to measure the temperature of different spatial locations, and its shape is not limited to a straight line. The structure can be changed into any spatial curve shape with a radius of curvature not less than 10 times its diameter, such as a circle, using a non-linear shape. structure; and because the chromium-nickel alloy wire is soft and has almost no elasticity, it can change with the shape of the measuring rod 2 and maintain the shape. At this time, the axis of the chromium-nickel alloy wire 4 is not the same as the measuring rod 2, and the output signal is slightly different Reduce but do not affect signal detection; Figure 4 shows a disc-shaped measuring rod with an inner diameter of 10mm. At the shaft center of rod 2, open through holes are used at both ends of the measuring rod;

The linear measuring rod (Figure 1) is a straight stainless steel tube with an inner diameter of 10mm and a wall thickness of 2mm and a length of 450mm;

The planar measuring rod (Figure 4) is a stainless steel spiral tube with a circular corrugated structure, the inner diameter is 10mm, the wall thickness is 2mm, the outer shell is disc-shaped, the radius of the inscribed circle is 100mm, and the number of turns is 1; 4 chromium-nickel alloy wires pass through the measurement The free extension of the two ends of the rod 2 is not fixed;

The Fe-Ga wire 3 is a waveguide wire with a length of 300 mm and a diameter of 1.0 mm, which is composed of Fe ₈₃ Ga ₁₇ .

The chromium-nickel alloy wire 4 is a waveguide wire with a length of 450 mm and a diameter of 0.8 mm, composed of Gr ₂₀ Ni ₈₀ , a Curie temperature of 1300° C., and a usable temperature range of room temperature to 1100° C.

Described pulse signal generation module 5, connects Fe-Ga wire 3 two ends by other electric wire in the cable; It is powered by 220V power supply line, provides DC power supply by AC-DC switching power supply circuit (the present invention uses circuit topology to adopt single-ended The flyback circuit can also adopt switching power supply topology such as full-bridge LLC), generate narrow pulse signal through FPGA, after isolation by chip 6N137, output pulse excitation by driving MOSFET chip IRF740 on-off control. Generate a square pulse wave with an amplitude of 30V, a frequency of 1800Hz, and a pulse width of 7 microseconds, which is applied to both ends of the Fe-Ga wire to generate a circumferential magnetic field.

The control sampling module 6 is connected to the detection coil 10 through a cable. TDC and its peripheral circuits based on ASIC or FPGA as the core chip (the CycloneⅣ series FPGA chip EP4CE22E22C8N of ALTERA Company and the high-resolution time-to-digital conversion chip TDC-GP22 of ACAM Company of Germany are used in this design), and the detection coil 10 output The signal is converted into a timeable pulse signal through differential amplification and hysteresis comparison, and the time interval is measured by the time-to-digital converter TDC. From the known sound velocity v-temperature T curve, the result is T=7601.974-2.44618*v, through the signal It supports conventional digital and analog signal output, including: RS485, RS232, current 4mA～20mA.

The ceramic sleeve 7 is an alumina ceramic tube with an inner diameter of 8mm and a wall thickness of 2mm, and the length of the ceramic sleeve 7 is 300mm, which is used to fix the permanent magnet 9 and the detection coil 10;

The damper 8 is a mesoporous silica airgel, a solid cylinder with a diameter of 8mm and a length of 10mm;

The inner diameter of the permanent magnet 9 is 10mm, the outer diameter is 13mm, the thickness is 3mm samarium cobalt YX28, the Curie temperature is 800°C, and the inner side is insulated (inorganic high-temperature electrical insulating coating, which is specifically used in the present invention is Hebei Zhisheng Weihua Co., Ltd. ZS-1071 high temperature resistant inorganic adhesive from Special Coatings Co., Ltd., the coating thickness is less than 0.1mm);

The detection coil 10 is wound with enameled wire with a wire diameter of 0.25mm (the nominal diameter of the wire is 0.25mm, the nominal cross-sectional area of the wire is 0.03142mm ² , and the maximum outer diameter is 0.289mm), and it is wound into a hollow cylinder with 600 turns , the inner diameter of the finished product is 10mm, the outer diameter is 10.25mm, and the length is 15mm. It is located at the right end of the Fe-Ga wire 3 and inserted into the outside of the ceramic sleeve 7 to receive the elastic torsional wave signal; the control sampling module 6 is used to calculate the pulse generation to receive the torsional wave signal time interval.

The electrical connection is that the two ends of the magnetostrictive material Fe-Ga wire 3 in the cylindrical shell 1 are connected to the pulse generation module 3 through cables, and the two ends of the detection coil 10 in the ceramic sleeve 7 are connected with the control sampling module 6 through cables. connected; the pulse signal generating module 5 and the control sampling module 6 are connected through a plurality of cables to supply DC5V and 12V power and receive their control signals.

The working principle of this case is shown in Figure 2. The original torsional wave signal generated by the Fe-Ga wire 3 is transmitted through the coupling interface 11 into the chromium-nickel alloy wire 4 for propagation, reflected at the end face 12, and then detected by the detection coil. 10 detect the reflected waveform signal;

The signal detected by the detection coil 10 includes the original torsional wave signal sent by the Fe-Ga wire 3, the reflected wave generated by the reflection of the torsional wave at the coupling interface 11, the torsional wave is transmitted through the coupling interface 11, and reflected at the end face 12 After that, it is transmitted again through the coupling interface 11 and detected by the detection coil 10. By placing the detection coil 10 at the leftmost end of the Fe-Ga wire 3, the original torsional wave signal and the signal reflected at the end face 12 can be superimposed to obtain enhanced.

The time delay value refers to the time difference between the torsional wave signal detected by the detection coil 10 and the torsional wave signal transmitted and detected by the reflected wave signal generated at the end face 12 of the chromium-nickel alloy wire 4, calculated The time-delay data diagrams at different temperature values are obtained, and then the length of the chromium-nickel alloy wire 4 is fixed, so as to obtain the variation curve of speed with temperature.

As shown in FIG. 3 , the length of the chromium-nickel alloy wire 4 is called d, and the relationship between the delay value t obtained through the two waveforms and the speed of sound is c=2d/t. The torsional wave signal generated by the Fe-Ga wire 3 is transmitted through the coupling interface 11 of the Fe-Ga wire 3 into the chromium-nickel alloy wire 4 for propagation, reflected at the coupling interface 11 and the end face 12, and is transmitted at the detection coil 10. The original signal waveform I is detected, and the reflected wave II is generated at the end face 12. The waveform data is detected by the detection coil 10 and then sent to the control sampling module 6 for subsequent signal analysis.

Example 1: Put the chromium-nickel alloy wire part of the sensor into a high-temperature furnace, heat it at room temperature -1000°C, and detect the change between the two waveforms through the detection coil, and the time difference between the two stress wave peaks is hours delay. The main purpose of this embodiment is to study the relationship between the delay value and the temperature as the temperature rises.

Experimental platform construction: Install the components according to the temperature sensor structure shown in Figure 1, and put the installed temperature sensor into the high-temperature furnace. As the temperature rises, use an oscilloscope to observe the output waveform of the detection coil.

The software or protocols involved in the present invention are all known technologies.

E为材料的杨氏弹性模量，kg/(s²·m)；ρ为材料的密度，kg/m³，因此可以作为检验温度的标准。相比传统超声温度传感器对超声换能器施加50～500V的脉冲电压需通过80d B增益(放大10000倍)下得到1V左右的输出，本设计在Fe-Ga丝两端施加30V，可在检测线圈两端不经放大器直接得到最大19.2mV最小4.96m V的电压输出；并且本实施例在工作温度1000℃的情况下，铬镍合金丝不会氧化，保证了其工作稳定性。Experimental process and results: As shown in Figure 5, the output voltage curve of the detection coil at 20°C is obtained. The first peak is the excitation pulse generated by the induced pulse generation circuit, and the second peak is the end face of the torsional wave in the measurement range. reflected wave. The time delay between the two peaks is 290.9us, calculated according to the velocity calculation formula v=2d/t, the wave velocity of the torsional wave T(0,1) at room temperature is 3093.8m/s, which is consistent with the theoretical value; as shown in the figure As shown in 6, put the chromium-nickel alloy wire part of the sensor into a high-temperature furnace, heat it at room temperature -1000°C, and detect the two peaks through the detection coil, and obtain that the time difference between the two stress wave peaks gradually increases with temperature; As shown in Figure 7, the time difference between the first and second peaks can be obtained by controlling the sampling module to collect the time delay value, and the relationship curve between the measured temperature and the time delay value can be obtained; as shown in Figure 8, according to the chromium-nickel alloy wire Length and measured time, calculate the fitting curve of torsional wave velocity at different temperatures, the linear relationship between torsional wave velocity and temperature can be obtained, which conforms to the relationship formula between torsional wave velocity v and temperature T

E is the Young's modulus of elasticity of the material, kg/(s ² ·m); ρ is the density of the material, kg/m ³ , so it can be used as a standard for checking the temperature. Compared with the traditional ultrasonic temperature sensor, the pulse voltage of 50-500V applied to the ultrasonic transducer needs to obtain an output of about 1V through 80dB gain (magnified by 10000 times), this design applies 30V at both ends of the Fe-Ga wire, which can The two ends of the coil directly obtain a maximum voltage output of 19.2mV and a minimum voltage of 4.96mV without an amplifier; and in this embodiment, the chromium-nickel alloy wire will not be oxidized when the working temperature is 1000°C, which ensures its working stability.

In order to enrich the application scenarios of this design, the following improvements are proposed: when using sensitive element materials such as chromium-nickel alloy wires for temperature measurement, the temperature measurement area can be flexibly configured by changing the shape of the sensitive element materials according to requirements; the shape of chromium-nickel alloy wires is not limited to The straight line shape can be bent into any space curve shape with a radius of curvature not less than 10 times its diameter in the temperature measurement range according to the needs of measuring the temperature of different spatial positions during use; based on the strong output signal of this design, it can be connected by connecting cables Set the transmitter at the remote control end to further improve reliability and maintainability.

Embodiment 2: Using Fe-Ga and a permanent magnet as the torsional wave signal generator, other parts of the structure are the same as in Embodiment 1, the difference is that the measuring rod is in the shape of Figure 4, and the chromium-nickel alloy wire is flexible and can be bent Go deep into the measuring rod in the shape of a flat disc, put the flat measuring rod into a cylindrical high-temperature furnace with a diameter of 240mm, heat it at room temperature -1000°C, and detect the change of the waveform. The main purpose of this embodiment is to verify the reliability of the device signal at high temperature, and to calculate the sound velocity of the torsional wave at different temperatures.

Construction of the experimental platform: install the components according to the structure of the temperature measuring sensor shown in Figure 4, and put the installed temperature measuring sensor into the high-temperature furnace. Other steps are the same as in Example 1, and the output waveform of the detection coil is observed with an oscilloscope.

Experimental process and results: The sensor device is heated from 20°C to 1000°C, and the detected voltage signal gradually decreases with the increase of temperature, the maximum is 13.1mV, and the minimum is 3.2mV. Compared with the traditional ultrasonic temperature sensor that applies a pulse voltage of 50 to 500V to the ultrasonic transducer, it needs to obtain an output of about 1V through an 80d B gain (amplified by 10,000 times), and this design is more stable with simpler excitation and detection devices. , Obvious detection signal, and get the real-time temperature in the plane space.

As can be seen from the above examples, the present invention utilizes the slow torsional wave velocity and the non-dispersibility of the T(0,1) mode through Fe-Ga wires, permanent magnets, and chromium-nickel alloy wires to broaden the magnetostriction The range of application of the effect and the Weidmann effect improves the sensitivity of the device measurement; the Curie temperature of the chromium-nickel alloy wire is higher than that of the magnetostrictive material, and it is less prone to oxidation than other sensitive element materials. Measure the time delay value of the torsional wave in the chromium-nickel alloy wire, so as to determine the transmission speed of the torsional wave in the chromium-nickel alloy wire, and sense the temperature of the surrounding medium in the chromium-nickel alloy wire area. This is a more reliable temperature sensor that can be applied to a wide range of temperature and temperature gradient measurements under complex and harsh working conditions such as high temperature, high pressure, closed environment, and strong vibration, and can reconfigure the temperature measurement range according to requirements.

The mechanism of this device is: the measurement of the sensing signal is determined according to the time difference relationship of the torsional wave signal, and the wave velocity obtained by calculating the time delay value between the torsional wave peaks at room temperature conforms to the theoretical value, and the distance between the observed waveforms is within As the temperature changes, the measured waveform can be determined to be the required torsional wave signal according to the signal relationship; summarizing the changing law with temperature, it can be considered that the wave velocity is changing with temperature, and the obtained relationship conforms to the derivation formula of speed changing with temperature, so as to determine the measurement precise. Using the Weidmann effect of the magnetostrictive material to vibrate at the position of the permanent magnet to generate torsional waves, using the slow propagation speed of the torsional wave and the non-dispersive characteristics of the T(0,1) mode, and then passing the torsional wave in the sensitive element material The velocity of propagation in to measure the temperature. Compared with the existing pulse reflection method temperature measurement structure, redesign the sensor structure, take advantage of the advantages of strong output signal, easy detection and high reliability of the new magnetostrictive material, and propose the following improvements: use magnetostrictive material and permanent magnet The original signal generator replaces the ultrasonic transducer as the generator of the guided wave, which reduces the influence of noise signals caused by high temperature and high frequency; the circular permanent magnet and the detection coil are not in direct contact with the waveguide wire, and only the permanent magnet and the detection coil are fixed The relative position does not change, it is not affected by vibration, and there is no vulnerable connection point; the chromium-nickel alloy material that is less prone to oxidation at high temperatures is used to expand the temperature measurement range.

In the description of the present invention provided by the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "vertical", "horizontal", "top", "bottom" etc. are based on the attached The orientation or positional relationship shown in the figure is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a reference to this invention. Invention Limitations.

Matters not covered in the present invention are known technologies.

Claims (3)

1. A Ni-Cr alloy temperature sensor based on magnetostrictive torsional waves is characterized by comprising a cylindrical shell, a measuring rod, fe-Ga wires, chromium-nickel alloy wires, a pulse signal generating module, a control sampling module, a ceramic sleeve, a damper, a permanent magnet and a detection coil;

wherein, the centers of the inner walls of the left side and the right side of the transverse shell are provided with grooves, and the two ends of the ceramic sleeve are respectively fixed on the two grooves; a damper is arranged inside the left side of the ceramic sleeve; a through hole is formed in the center of the right side of the shell, and a measuring rod is fixedly connected to the outside of the through hole; the axes of the shell and the measuring rod are the same; the right end of the measuring rod is closed, one end of the chrome-nickel alloy wire is fixed in the center of the inner wall of the right end of the measuring rod, the other end of the chrome-nickel alloy wire penetrates through the measuring rod and enters the shell, the right part of the chrome-nickel alloy wire in the ceramic sleeve is connected with the right end of the Fe-Ga wire, and the left end of the Fe-Ga wire penetrates through the inside of the ceramic sleeve and penetrates through the damper and is fixed in the center of the inner wall of the left end of the shell; the connection part of the chrome-nickel alloy wire and the Fe-Ga wire is in a water drop shape; a detection coil is sleeved outside the ceramic sleeve at the right end of the Fe-Ga wire; an annular permanent magnet is sleeved outside the ceramic sleeve between the damping coil and the detection coil; the upper part and the lower part of the shell are respectively provided with a pulse signal generating module and a control sampling module, wherein the pulse signal generating module is connected with two ends of the Fe-Ga wire through a lead; the detection coils are respectively connected with two ends of the control sampling module;

the measuring rod is a linear measuring rod or a planar measuring rod;

the linear measuring rod is a stainless steel straight pipe;

the shell of the plane type measuring rod is made of a stainless steel spiral pipe with a circular corrugated structure;

the chromium-nickel alloy wire comprises the following components of Cr ₂₀ Ni ₈₀ ；

The component of the Fe-Ga wire is Fe ₈₃ Ga ₁₇ ；

The length ratio of the Fe-Ga wires to the chrome-nickel alloy wires is 0.4-0.67, and the diameter ratio is 1.2-1.5;

the length of the cylindrical shell is 1-1.1 times of that of the Fe-Ga wire;

the cross section of the drop-shaped laser welding coupling part is oval, the length is 2-4 mm, and the maximum diameter is 1.5-2 mm;

the length of the measuring rods in the temperature measuring units in different intervals is the same or different, and the length range is 450-650 mm;

the length of the ceramic sleeve is 1-1.1 times of the length of the cylindrical shell;

the detection coil is a hollow cylinder wound by enameled wires and is wound by 300-1500 turns, and the length of the detection coil is 10-20mm;

the length of the annular permanent magnet is the same and is 2-5 mm;

the damping length is 5-30mm, and the diameter is 5-10mm;

the distance between the damping and the left end of the permanent magnet is 50-150mm.

2. The Ni-Cr alloy temperature sensor based on a magnetostrictive torsional wave according to claim 1, characterized in that the right end of the detection coil is spaced from the drop-shaped junction by 1 to 5mm;

the distance between the left end of the detection coil and the annular permanent magnet is 150-250 mm.

3. The Ni-Cr alloy temperature sensor based on magnetostrictive torsional waves according to claim 1, wherein

The measuring rod and the shell are made of non-ferromagnetic stainless steel;

the ceramic shell is an alumina ceramic sleeve;

the annular permanent magnet is made of samarium cobalt YX28, and the inner side of the annular permanent magnet is insulated;

the damping is mesoporous silica aerogel.

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