CN112834069B - Ni-Cr alloy temperature sensor based on magnetostrictive torsional wave - Google Patents
Ni-Cr alloy temperature sensor based on magnetostrictive torsional wave Download PDFInfo
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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
Technical Field
The invention combines magnetostrictive material with sensitive element material, is applied to the field of temperature sensors, mainly relates to Fe-Ga filiform material generating magnetostrictive effect and nickel-chromium alloy wire used as sensitive element material, can be applied to temperature measurement and realizes real-time temperature monitoring.
Background
Magnetostrictive temperature sensors have the potential to provide reliable temperature measurements for many applications, including temperature monitoring and spatial temperature distribution display of real-time temperatures and the entire industrial process in locations where temperature monitoring is critical, such as glass and low melting point metal melting, processing industries, nuclear power plants, and the like. Thermocouples, thermal resistors and non-contact thermometry, which are commonly used in industry, have many problems, such as: the thermocouple and the thermal resistance temperature sensor are often influenced by temperature drift in the long-term working process, the amplitude of the output signal voltage is small, the output signal voltage is easy to be interfered by electromagnetism and difficult to transmit in a long distance, and one sensor can only measure the temperature of one position; the non-contact temperature measurement method comprises various optical temperature measurement methods and radiation pyrometers, such as infrared temperature measurement, fiber black body cavity temperature measurement and other technologies, wherein a temperature measurement element does not need to be in contact with a measured medium, a temperature field during combustion is not influenced, but smoke generated during combustion of a propellant pollutes a photoelectric detector on one hand, and a test environment has certain influence on emissivity on the other hand, so that the temperature measurement data has a very large difference with theoretical calculation; although the radiation pyrometer can keep a longer distance from a high-temperature area and theoretically has no upper temperature measurement limit, the radiation rate of a target system is difficult to determine, the measurement precision is greatly influenced by the emissivity, components, concentration and an environmental field, and more uncertain factors exist, so the reliability of test data is lower. However, in some industrial applications, the temperature under high temperature and ultra-high temperature environments must be monitored for a long time, for example, in ammunition explosion, nuclear experiments and aerospace engine operation in the military industry field, in pressurizers and reheaters in engine cylinders of pressurized water reactors, diesel engines, steam turbines and the like in the energy field, in reactors and other large-scale equipment in the fields of petroleum, chemical engineering and the like, and in the process monitoring of the synthesis and process of other materials, the temperature measurement of high-temperature fluid at a position required by long-time ultra-high temperature in-situ testing cannot be avoided. Furthermore, failure of the connection point in the thermocouple in high temperature and strong vibration environments also results in high costs, especially when compensating wires or the like are used.
With the continuous development of modern industrialization, the guided wave temperature measurement technology is increasingly widely applied in industry, wherein the requirement on the quality of guided wave signals is gradually increased. The guided wave temperature measurement mainly comprises two methods based on ultrasonic waves and low-frequency sound waves, the ultrasonic waves have good directivity, but are attenuated quickly, and the guided wave temperature measurement is mainly used for short-distance temperature measurement; the low-frequency sound wave can be spread for a longer distance, and is already used for measuring the indoor temperature, the flame temperature of a hearth and the temperature of lake water, the research of measuring the air temperature by using the low-frequency sound wave mainly focuses on two-dimensional tomography research, and the temperature measurement precision of a single path 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 sound wave propagation time change caused by temperature cannot be detected; the distance measured between the two microphones is directly taken as the actual sound wave propagation path length, and the time delay of the system is ignored, so that the sound velocity measurement is inaccurate. In terms of ultrasonic thermometry sensors, the principle division is mainly focused on the pulse reflection method, the resonance method, and the pulse penetration method. The resonance method is high in measurement accuracy but long in measurement time, and the penetration method requires two ultrasonic probes and cannot achieve spontaneous emission and spontaneous collection. The ultrasonic echo signal analysis difficulty of the pulse reflection method is high, the signal is small and easy to interfere, and the method has the defects in practical application, is unreliable in industrial application and is difficult to realize large-scale commercial production. The disadvantages of the traditional sensitive element materials such as thorium tungsten alloy, tungsten rhenium alloy, sapphire and stainless steel as the waveguide rod are mainly reflected in that: (1) Except a few expensive materials, most waveguide rod materials are easy to oxidize at a high temperature of over 800 ℃; (2) The data processing and result display equipment is complex and high in cost; (3) The ultrasonic transducer is relied on, and the hysteresis characteristic and the characteristic which is easily influenced by temperature of the ultrasonic transducer limit the measurement accuracy; (4) When ultrasonic waves are transmitted in a cylindrical waveguide rod made of uniform materials, the ultrasonic waves are reflected for multiple times at the boundary and the etching position of the waveguide rod, so that the phenomena of geometric dispersion and complex interference occur in the waveguide rod, and great difficulty is caused to signal processing; (5) The higher the ultrasonic frequency is, the easier the ultrasonic frequency is to attenuate, which is not beneficial to expanding the measuring range. The magnetostrictive material is directly used as a sensitive element material, and the disadvantage is mainly that (1) the Curie temperature of the magnetostrictive material is only 980 ℃, and the temperature measuring range is limited; (2) Under the condition of over 600 ℃, the signal attenuation is serious, the signal-to-noise ratio becomes extremely poor, the magnetostrictive material is used as a waveguide rod, and the measurement range is only room temperature-600 ℃; (3) The magnetostrictive material expands seriously by heating, which causes obvious actual error.
The previously published 'an absolute ultrasonic magnetostrictive temperature sensor' of the inventor proposes a temperature sensor structure using magnetostrictive materials as a core, but the temperature sensor structure still has defects in higher temperature measurement and reliability: (1) The electrical insulation of the wire in the measuring rod is difficult to manufacture, the application of insulating materials such as silica gel glass fiber tubes and the like at the temperature of over 600 ℃ is difficult to realize, the complex structures of the insulating materials such as ceramic glass and the like are difficult to process, and the use in a vibration environment is limited; (2) In the patent, the linear expansion coefficient of the magnetostriction materials such as Fe-Ga is larger, and the reliability of the sensor is reduced by introducing a mechanical motion structure of a constant-elasticity device; (3) In the original patent, the permanent magnet is arranged in the measuring rod of the temperature measuring area, and the permanent magnet has the risk of demagnetization in high-temperature and vibration environments, so that the service life of the sensor is difficult to ensure. Therefore, there is a need for an alternative to temperature sensors that is simple in excitation, more reliable at high temperatures, and adaptable to complex and harsh conditions.
The invention content is as follows:
aiming at the problems of poor quality of ultrasonic temperature measurement signals, low Curie temperature of sensitive element materials, easiness in oxidation and the like, the invention designs a Ni-Cr alloy temperature sensor based on magnetostrictive torsional waves for realizing the accurate measurement of the temperature sensor on real-time temperature. The sensor combines a magnetostrictive material with a sensitive element material, and the chromium-nickel alloy wire and the Fe-Ga wire are physically connected by laser welding instead of a coupling agent, and are connected into a whole wire shape, and the laser welding part is in a drop shape, so that the energy-gathering amplification effect is achieved, and a torsional wave signal generated by the Wedgeman effect can be effectively transmitted at the welding part of the chromium-nickel alloy wire and the Fe-Ga wire; and meanwhile, the detection coil is fixed at the position, close to the chrome-nickel alloy wire, of the right end of the Fe-Ga wire, a waveform before a torsional wave is transmitted into the chrome-nickel alloy wire from the Fe-Ga wire and a waveform just transmitted to the Fe-Ga wire from the chrome-nickel alloy wire are detected through the Weidman inverse effect, so that the time interval between the two waveforms is the time for the torsional wave to propagate in the chrome-nickel alloy wire, the Weidman effect and the Weidman inverse effect of the Fe-Ga wire serving as a magnetostrictive material are fully utilized, and the effects of signal generation and detection are achieved.
The technical scheme of the invention is as follows:
a Ni-Cr alloy temperature sensor based on magnetostrictive torsional waves comprises a cylindrical shell, a measuring rod, fe-Ga wires, chrome-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 distance from the right end of the detection coil to the drop-shaped connection position is 1-5 mm;
the distance from the left end of the detection coil to the annular permanent magnet is 150-200 mm;
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, and the shape of the shell is a plane volute line;
the measuring rod and the shell are made of non-ferromagnetic stainless steel and can resist temperature of 1400 ℃;
the ceramic sleeve is an alumina ceramic sleeve;
the chrome-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 circular permanent magnet is made of samarium cobalt YX28, and the inner side of the circular permanent magnet is insulated;
the damper is mesoporous silica aerogel;
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 ratio of the Fe-Ga wires to the chrome-nickel alloy wires is 0.4 to 0.67, the diameter ratio is 1.2 to 1.5,
the length of the cylindrical shell is 1-1.1 times of that of the Fe-Ga wire;
the length of the ceramic sleeve is 1-1.1 times of the length of the cylindrical shell;
the measuring rods in the temperature measuring units in different intervals have the same or different lengths, and the length range is 450-650 mm;
the length of the annular permanent magnet is 2-5 mm;
the damping is 15-30mm in length and 5-10mm in diameter;
the distance of the damping is 50-150mm according to the left end of the permanent magnet;
the detection coil is a hollow cylinder wound by enameled wires, and is wound by 300-1500 turns with the length of 10-20mm.
The invention has the substantive characteristics that:
the Ni-Cr alloy temperature sensor based on the magnetostrictive torsional waves is composed of eight parts, namely a cylindrical shell, a Fe-Ga wire, a chrome-nickel alloy wire, a permanent magnet, a measuring rod, a detection coil, a ceramic sleeve, a control sampling module and a pulse signal generating module, and can accurately measure the temperature in a measured area. The ceramic sleeve is made of alumina ceramic material, and the shell is used for fixing and protecting internal elements; the annular permanent magnet is used for generating an axial magnetic field, and an instantaneous torsional wave is formed inside the Fe-Ga wire under the combined action of a circumferential magnetic field generated by a unidirectional pulse excitation signal; torsional wave signals in the chrome-nickel alloy wire are transmitted to the chrome-nickel alloy wire from the Fe-Ga wire, and the signals are reflected on the end face of the chrome-nickel alloy wire; accurately measuring the temperature by determining a time delay value between a signal generation wave and a reflected wave; the Curie temperature of the chromium-nickel alloy wire is as high as 1400 ℃ or above, the working temperature is 1200 ℃, the thermal expansion is weak at high temperature, and the measurement range can be expanded to 1000 ℃; the torsional wave speed is slower than that of the longitudinal wave, and the dispersion phenomenon does not occur at high temperature and high frequency, so that the sensitivity is high and the detection is easy; the acquisition card collects the waveform signals and displays the waveform signals in a computer.
The invention has the beneficial effects that:
1. by utilizing the magnetostrictive effect of the Fe-Ga wires, a circumferential magnetic field generated under the excitation pulse is combined with an axial magnetic field generated by the permanent magnet to generate a torsional wave signal and transmit the torsional wave signal. The sensor effectively reduces the influence of noise signals caused by high voltage, high frequency and vibration in ultrasonic temperature measurement.
2. The torsional wave T (0, 1) has a slower wave speed than the longitudinal wave L (0, 1), no dispersion phenomenon at high temperature and high frequency, high sensitivity and easy detection. The axisymmetric torsional mode is a detection mode commonly used in ultrasonic guided waves, in particular a T (0, 1) mode excited in a waveguide lead screw model. The wave packet structure of the T (0, 1) mode is simple, the incident signal can keep the signal waveform in the transmission process, and the transmission is longer and the attenuation is smaller; the propagation speed of the modal guided wave is basically not influenced by frequency change in a certain frequency range, namely the modal guided wave has good non-frequency dispersion characteristics; only circumferential vibration displacement is adopted, radial displacement is not adopted, energy leakage is less in the guided wave propagation process, and detection is easy.
3. And converting the time delay value t of the two reflections into the speed c =2d/t of the torsional wave propagating in the sensing element material by using the fixed length d of the sensing element material, thereby determining the temperature at the moment. The etching of the node 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 the chrome-nickel alloy wire is as high as 1400 ℃ and above, the working temperature of the chrome-nickel alloy wire reaches 1200 ℃, the chrome-nickel alloy wire is weak in thermal expansion at high temperature, the measuring range can be expanded to be above 1000 ℃, errors are effectively reduced, and the working reliability of the sensor in a high-temperature environment is improved.
5. The permanent magnet and the lead are arranged in the shell far away from the high-temperature environment, so that the demagnetization phenomenon of the permanent magnet and the dependence on high-temperature-resistant insulating materials of the electric connecting lead are greatly reduced, and the manufacturing cost of the sensor is effectively reduced.
6. Based on the improvement, the configuration of each part is optimized through a large number of experiments, the Ni-Cr alloy temperature sensor based on magnetostrictive torsional waves is designed, 600 circles of detection coils are obtained through experiments, excitation pulses are square pulse waves with the amplitude of 30V, the frequency of 1200Hz and the pulse width of 5 microseconds, the generated output voltage is maximum, and a fitting curve T = of sound velocity and temperature is measured
7601.974-2.44618 v, can be used as the basis for detecting temperature.
7. Compared with a pulse reflection method guided wave temperature measuring device, the ultrasonic transducer is applied with 50-500V pulse voltage (the applied voltage is greatly different due to different types and coupling conditions of the piezoelectric probes) and output of about 1V is obtained under 80 db gain (amplified by 10000 times). The design has stronger original output signals (without an amplifier), can directly set a transmitter at a remote control end through a connecting cable, further improves the reliability and maintainability, and can be applied to complex severe working conditions such as high temperature, high pressure, closed environment, strong vibration and the like.
Drawings
FIG. 1 is a structural diagram of a Ni-Cr alloy temperature sensor based on magnetostrictive torsional waves according to the present invention;
FIG. 2 is a graph of incident waves versus reflected and transmitted waves in accordance with the present invention;
FIG. 3 is a schematic diagram of the acoustic wave propagation of a Ni-Cr alloy temperature sensor based on magnetostrictive torsional waves according to the present invention;
FIG. 4 is a schematic view of a planar sensor;
FIG. 5 is a waveform diagram of data at 20 ℃ and normal temperature of the Ni-Cr alloy temperature sensor based on magnetostrictive torsional waves according to the invention;
FIG. 6 is a waveform diagram of the time-delay data from normal temperature to 1000 ℃ of the Ni-Cr alloy temperature sensor based on magnetostrictive torsional waves according to the present invention;
FIG. 7 is a measured output temperature profile;
FIG. 8 is a curve fitted to the torsional wave velocity versus temperature.
The device comprises a shell 1, a measuring rod 2, a 3Fe-Ga wire, a 4 Cr-Ni alloy wire, a 5 pulse signal generating module, a 6 control sampling module, a 7 ceramic sleeve, an 8 damping coil, a 9 permanent magnet and a 10 detection coil, wherein the shell is provided with a first end and a second end;
Detailed Description
In the invention, magnetostrictive torsional waves emitted from the Fe-Ga wires are propagated in the nichrome wires, the torsional wave transmission time is determined by monitoring the torsional wave signal transmission waveform, and then the influence of the torsional wave velocity along with the temperature change is determined, and the characteristics of strong original output signals and good oxidation resistance and high Curie temperature of the sensitive element nichrome wires in a magnetostrictive material Fe-Ga alloy wire excitation mode are fully combined. Structurally, the chrome-nickel alloy wire and the Fe-Ga wire are physically connected by laser welding instead of a coupling agent, the connection is a whole wire shape, the laser welding position is in a water drop shape, the energy-gathering amplification effect is achieved, and a torsional wave signal generated by the Wedgeman effect can be effectively transmitted at the welding position of the chrome-nickel alloy wire and the Fe-Ga wire; and meanwhile, the detection coil is fixed at a position, close to the chrome-nickel alloy wire, on the Fe-Ga wire, a waveform before the torsional wave is transmitted into the chrome-nickel alloy wire from the Fe-Ga wire and a waveform just transmitted to the Fe-Ga wire from the chrome-nickel alloy wire are detected through the Weidman inverse effect, so that the time interval between the two waveforms is the time for the torsional wave to propagate in the chrome-nickel alloy wire, the Weidman effect and the Weidman inverse effect of the Fe-Ga wire serving as a magnetostrictive material are fully utilized, and the signal generation and detection effects are realized. The temperature sensor adopts Fe-Ga wires and chrome-nickel alloy wires as core components, one end of the Fe-Ga wires penetrates through a damper and is fixed at the left end of a ceramic sleeve, the other end of the Fe-Ga wires is connected with the chrome-nickel alloy, the Fe-Ga wires and the chrome-nickel alloy wires are coupled by laser welding, when a circumferential excitation magnetic field generated by pulse current and an axial bias magnetic field generated by a permanent magnet generate Wedgeman effect, because an instantaneous circumferential excitation magnetic field is applied, instantaneous deformation is generated in the Fe-Ga wires, and then torsional waves which are respectively transmitted to two ends of the Fe-Ga wires are generated; in addition, the chrome-nickel alloy is coupled with the Fe-Ga wire, so that a part of torsional waves are reflected on the end surface, and the other part of torsional waves are projected and then continuously transmitted along the chrome-nickel alloy wire to be reflected again after reaching the end surface of the chrome-nickel alloy wire; finally, detecting a torsional wave signal by using a detection coil, wherein the coil fixes one end of the Fe-Ga wire connected with the chrome-nickel alloy wire and is connected with a control sampling module; the torsional wave has a slower wave speed than the longitudinal wave, and is not easy to disperse under high temperature and high frequency conditions, so that the sensitivity of a detection signal can be increased, and the measurement precision is improved. In the device, when the Fe-Ga wire and the chrome-nickel alloy are coupled and the torsional wave is transmitted to the coupling interface, one part of the torsional wave is reflected, the other part of the torsional wave is transmitted to the chrome-nickel alloy wire through the interface, so that the torsional wave can be continuously transmitted in the chrome-nickel alloy wire, and the time delay data graphs at different temperatures can be obtained by recording the time delay data among the waveforms, thereby obtaining the change curve of the propagation speed of the torsional wave along with the temperature. The invention effectively overcomes the defects that the traditional ultrasonic temperature sensor depends on an ultrasonic transducer, the original signal is weak, the vibration is easy to occur after multiple times of etching, the sensitive element material is easy to oxidize, and the like; compared with the magnetostrictive material directly used as the sensitive element material, the high Curie temperature of the nickel-chromium alloy enlarges the measuring range of the temperature sensor. Experimental results show that when the temperature is measured, 30V is applied to two ends of a Fe-Ga wire (the length is 300 mm), and voltage output of 19.2mV at maximum and 4.96mV at minimum can be directly obtained at two ends of a detection coil without an amplifier.
The invention is further described in detail below with reference to the figures. The present embodiment is merely a specific description of the invention, and is not to be construed as limiting the scope of protection.
The Ni-Cr alloy temperature sensor based on magnetostrictive torsional waves is shown in figure 1, and the main body part of the sensor comprises a cylindrical shell 1, a measuring rod 2, a Fe-Ga wire 3, a chromium-nickel alloy wire 4, a pulse signal generating module 5, a control sampling module 6, a ceramic sleeve 7, a damper 8, a permanent magnet 9 and a detection coil 10;
wherein, the centers of the inner walls of the left and right sides of the transverse shell 1 are provided with grooves, and the two ends of the ceramic sleeve 7 are respectively fixed on the two grooves (the side walls of the two ends of the ceramic sleeve 7 are provided with through holes, which is convenient for the lead to be connected in); a damper 8 is arranged inside the left side of the ceramic sleeve 7; a through hole is formed in the center of the right side of the shell 1, and a measuring rod 2 is fixedly connected (welded) outside the through hole; the axes of the shell 1 and the measuring rod 2 are the same; the right end of the measuring rod 2 is closed, one end of the chrome-nickel alloy wire 4 is fixed at the center of the inner wall of the right end of the measuring rod 2, the other end of the chrome-nickel alloy wire passes through the measuring rod 2 and enters the shell 1, the right part of the inside of the ceramic sleeve 7 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, passes through the damper 8 and is fixed at the center of the inner wall of the left end of the shell 1; the chrome-nickel alloy wire 4 and the Fe-Ga wire 3 are connected by laser welding, and the connection part is in a water drop shape; the right end of the Fe-Ga wire 3 is sleeved with a detection coil 10; an annular permanent magnet 9 is sleeved outside the ceramic sleeve 7 between the damper 8 and the detection coil 10, and the annular permanent magnet 9 on the ceramic sleeve 7 must be outside a detection blind area of the detection coil 10;
the upper part and the lower part of the shell 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 with the two ends of the Fe-Ga wire 3 through a lead; the detection coils 10 are respectively connected with two ends of the control sampling module 6;
the axes of the shell 1, the measuring rod 2, the Fe-Ga wire 3, the chrome-nickel alloy wire 4 and the ceramic sleeve 7 are the same;
the inner diameter of the cylindrical shell 1 is 60mm, the length is 300mm, the wall thickness is 2mm, and stainless steel with the material grade of 430 is used;
the measuring rod 2 is a linear measuring rod or a planar measuring rod. The measuring rod 2 can be used for measuring the temperature requirements of different space positions in use, the shape is not limited to a linear shape, the structure can be changed into any space curve shape with the curvature radius not smaller than 10 times of the diameter, for example, the shape is circular, and a nonlinear structure is used; the chrome-nickel alloy wire is soft in texture and almost has no elasticity, so that the chrome-nickel alloy wire can change along with the shape of the measuring rod 2 and keep the shape, at the moment, the axis of the chrome-nickel alloy wire 4 is not the same as that of the measuring rod 2, the output signal is slightly reduced, and the signal detection is not influenced; fig. 4 shows a disc-shaped measuring rod, the inner diameter of which is 10mm, so that the chrome-nickel alloy wire 4 is not fixed at the axis of the measuring rod 2 for facilitating the combination of the chrome-nickel alloy wire 4 and the measuring rod 2, and open through holes are adopted at the two ends of the measuring rod;
the linear measuring rod (figure 1) is a stainless steel straight pipe, the inner diameter is 10mm, the wall thickness is 2mm, and the length is 450mm;
the plane type measuring rod (figure 4) is a stainless steel spiral pipe with a circular corrugated structure, the inner diameter is 10mm, the wall thickness is 2mm, the shell is disc-shaped, the radius of an inscribed circle is 100mm, and the number of turns is 1; the chrome nickel alloy wire 4 penetrates through the measuring rod 2, and then the free extension of the two ends is not fixed;
the Fe-Ga wire 3 is a waveguide wire with the length of 300mm and the diameter of 1.0mm and is formed by Fe 83 Ga 17 。
The chrome-nickel alloy wire 4 is a waveguide wire with the length of 450mm and the diameter of 0.8mm and is formed into Gr 20 Ni 80 The Curie temperature is 1300 ℃, and the usable temperature range is room temperature-1100 ℃.
The pulse signal generating module 5 is connected with two ends of the Fe-Ga wire 3 through other wires in the cable; the power supply is realized through a 220V power line, an AC-DC switching power supply circuit provides a direct current power supply (the circuit topology of the invention adopts a single-ended flyback circuit, and can also adopt switching power supply topologies such as full-bridge LLC and the like), a narrow pulse signal is generated through an FPGA (field programmable gate array), and after the narrow pulse signal is isolated by a chip 6N137, pulse excitation is output through the control of on-off of an IRF740 driving an MOSFET chip. Square pulse waves with the amplitude of 30V, the frequency of 1800Hz and the pulse width of 7 microseconds are generated and are added at the two ends of the Fe-Ga wire to generate a circumferential magnetic field.
The control sampling module 6 is connected with the detection coil 10 through a cable. The method comprises the steps that a TDC which is a core chip and based on an ASIC or an FPGA and a peripheral circuit thereof are adopted (in the design, a Cyclone IV series FPGA chip EP4CE22E22C8N of ALTERA company and a high-resolution time-to-digital conversion chip TDC-GP22 of Germany ACAM company are adopted), signals output by a detection coil 10 are converted into timeable pulse signals through differential amplification and hysteresis comparison, a result T =7601.974-2.44618 v is obtained through a known sound velocity v-temperature T curve through a time-to-digital converter TDC measurement time interval, and the result T =7601.974-2.44618 v is transmitted through a signal line, so that the conventional digital analog signal output is supported, and the method comprises the following steps: RS485, RS232 and current of 4 mA-20 mA.
The ceramic sleeve 7 is an alumina ceramic tube, the inner diameter of the ceramic sleeve is 8mm, the wall thickness of the ceramic sleeve is 2mm, the length of the ceramic sleeve 7 is 300mm, and the ceramic sleeve is used for fixing the permanent magnet 9 and the detection coil 10;
the damper 8 is a mesoporous silica aerogel, and is a solid cylinder with the diameter of 8mm and the length of 10mm;
the inner diameter of the permanent magnet 9 is 10mm, the outer diameter is 13mm, the samarium cobalt YX28 with the thickness of 3mm is used, the Curie temperature is 800 ℃, the inner side is subjected to insulation treatment (an inorganic high-temperature electric insulation coating, the invention specifically uses ZS-1071 high-temperature resistant inorganic adhesive of Hebei Yongwei Huate paint Limited, and the coating thickness is less than 0.1 mm);
the detection coil 10 has a wire diameter of 0.25mm (nominal diameter of wire is 0.25mm, and nominal cross-sectional area of wire is 0.03142 mm) 2 Maximum outer diameter0.289 mm) enameled wire, winding into a hollow cylinder, winding into 600 turns, wherein the finished product has the inner diameter of 10mm, the outer diameter of 10.25mm and the length of 15mm, is positioned at the right end of the Fe-Ga wire 3, is sleeved outside the ceramic sleeve 7 and is used for receiving an elastic torsional wave signal; the time interval from the pulse generation to the reception of the torsional wave signal is calculated by controlling the sampling module 6.
Wherein, the electrical connection is that two ends of a magnetostrictive material Fe-Ga wire 3 in the cylindrical shell 1 are connected with the pulse generation module 3 through cables, and two ends of a detection coil 10 in the ceramic sleeve 7 are connected with the control sampling module 6 through cables; the pulse signal generating module 5 and the control sampling module 6 are connected through a plurality of flat cables, and supply DC5V and 12V power supplies to the modules and receive control signals of the modules.
The working principle of the scheme is shown in fig. 2, an original torsional wave signal generated by the Fe-Ga wire 3 is transmitted by a coupling interface 11 and transmitted into the chrome-nickel alloy wire 4 for propagation, and is reflected at an end face 12, and a reflected waveform signal is detected by a detection coil 10;
the signals detected by the detection coil 10 comprise original torsional wave signals sent by the Fe-Ga wire 3, reflected waves generated by the reflection of the torsional waves at the coupling interface 11 are transmitted through the coupling interface 11, the torsional waves are transmitted through the coupling interface 11 again after being reflected at the end face 12, the signals are detected by the detection coil 10, and the superposition of the original torsional wave signals and the signals reflected at the end face 12 can be enhanced by adopting a method that the detection coil 10 is placed at the leftmost end away from the Fe-Ga wire 3.
The time delay value is a time difference between a torsional wave signal detected by the detection coil 10 and a torsional wave signal which is generated at the end face 12 of the chrome-nickel alloy wire 4 and is transmitted and detected, a time delay data graph under different temperature values is obtained through calculation, and then the length of the chrome-nickel alloy wire 4 is fixed, so that a speed change curve along with the temperature is obtained.
As shown in fig. 3, the length of the chrome-nickel alloy wire 4 is referred to as d, and the relationship between the delay value t obtained from the two waveforms and the sound speed is c =2d/t. The torsional wave signal generated by the Fe-Ga wire 3 is transmitted from a coupling interface 11 of the Fe-Ga wire 3 and is transmitted into the chrome-nickel alloy wire 4 for propagation, reflection occurs at the coupling interface 11 and an end face 12, an original signal waveform I is detected at a detection coil 10, a reflected wave II is generated at the end face 12, and waveform data detected by the detection coil 10 are transmitted to a control sampling module 6 for subsequent signal analysis.
Example 1: the chrome-nickel alloy wire part of the sensor is put into a high-temperature furnace, the chrome-nickel alloy wire part is heated within the range of room temperature to 1000 ℃, the change between two waveforms is detected through a detection coil, and the time difference between two stress wave peak values is a time delay value. The main purpose of this embodiment is to study the temperature-dependent time delay value with temperature.
Building an experiment platform: each part is installed according to the structure of the temperature sensor shown in figure 1, the installed temperature sensor is placed in a high-temperature furnace, and an oscilloscope is adopted to observe the output waveform of the detection coil along with the rise of the temperature.
The software or protocol involved in the present invention is well known in the art.
Experimental procedures and results: as shown in fig. 5, the output voltage curve of the detection coil at 20 ℃ is obtained, the first peak is the induced excitation pulse generated by the pulse generation circuit, and the second peak is the end-face reflected wave of the torsional wave in the measurement interval. The time delay value between the two wave crests is 290.9us, the time delay value is calculated according to a speed calculation formula v =2d/T, the wave speed of the torsional wave T (0, 1) at the normal temperature is 3093.8m/s, and the wave speed is matched with a theoretical value; as shown in fig. 6, the chrome-nickel alloy wire of the sensor is placed in a high temperature furnace, heated in the range of room temperature to 1000 ℃, and two wave peaks are detected by a detection coil, so that the time difference between the two stress wave peak values is gradually increased along with the temperature; as shown in fig. 7, the sampling module is controlled to acquire the time difference between the first peak and the second peak, so as to obtain a relation curve between the measured temperature and the time delay value; as shown in FIG. 8, according to the length of the chrome-nickel alloy wire and the measured time, a fitting curve of the wave velocity of the torsional wave at different temperatures is calculated, so that a linear relation between the wave velocity of the torsional wave and the temperature can be obtained, and the linear relation conforms to a relation formula between the wave velocity v of the torsional wave and the temperature T
E is the young's modulus of elasticity of the material,kg/(s 2 m); rho is the density of the material, kg/m 3 And thus can be used as a standard for checking temperature. Compared with the traditional ultrasonic temperature sensor which applies 50-500V pulse voltage to an ultrasonic transducer and obtains the output of about 1V under the condition of 80 db gain (amplification of 10000 times), the design applies 30V at two ends of the Fe-Ga wire, and can directly obtain the voltage output of 19.2mV at maximum and 4.96m V at minimum at two ends of a detection coil without an amplifier; in addition, in the embodiment, under the condition that the working temperature is 1000 ℃, the chromium-nickel alloy wire cannot be oxidized, so that the working stability of the chromium-nickel alloy wire is ensured.
In order to enrich the application scene of the design, the following improvements are provided: when a sensitive element material such as a chrome-nickel alloy wire is used for measuring temperature, the temperature measuring area can be flexibly configured by changing the shape of the sensitive element material according to requirements; the shape of the chrome-nickel alloy wire is not limited to a straight line shape, and the chrome-nickel alloy wire can be bent into any space curve shape with the curvature radius not less than 10 times of the diameter in a temperature measuring area according to the requirements of measuring the temperature of different space positions in use; based on the stronger output signal of this design, accessible connecting cable sets up the changer at the remote control end, further improves reliability and maintainability etc..
Example 2: the structure of the device is the same as that of the device in example 1 except that Fe-Ga and a permanent magnet are used as a torsional wave signal generator, the device is structurally characterized in that a measuring rod is in a shape of figure 4, a chrome-nickel alloy wire is flexible and can be bent to extend into the measuring rod in a plane disc shape, the plane type measuring rod extends into a cylindrical high-temperature furnace with the diameter of 240mm, and the device is heated within the range of room temperature to 1000 ℃ to detect the change of a waveform. The main purpose of the embodiment is to verify the reliability of the device signal at high temperature and calculate the sound velocity of the torsional wave at different temperatures.
Establishing an experiment platform: each part was installed according to the temperature sensor structure shown in fig. 4, and the installed temperature sensor was placed in a high temperature furnace, and the waveform output from the detection coil was observed by an oscilloscope in the same manner as in example 1.
Experimental procedures and results: the temperature of the sensor device is increased from 20 ℃ to 1000 ℃, and the detected voltage signal is gradually reduced along with the temperature increase, wherein the maximum voltage signal is 13.1 mV, and the minimum voltage signal is 3.2 mV. Compared with the traditional ultrasonic temperature sensor, the ultrasonic transducer applied with 50-500V pulse voltage needs to obtain about 1V output under the condition of 80 db gain (amplification of 10000 times), the design obtains more stable and obvious detection signals under simpler excitation and detection devices, and obtains real-time temperature in a plane space.
The embodiment shows that the application range of the magnetostrictive effect and widemann effect is widened by using the slow torsional wave speed and the non-dispersive property of the T (0, 1) mode through the Fe-Ga wire, the permanent magnet and the chrome-nickel alloy wire, so that the measurement sensitivity of the device is improved; the chromium-nickel alloy wire has a Curie temperature higher than that of a magnetostrictive material and is less prone to oxidation than other sensitive element materials. And measuring the time delay value of the transmission of the torsional wave in the chrome-nickel alloy wire, thereby determining the transmission speed of the torsional wave in the chrome-nickel alloy wire and sensing the temperature of the surrounding medium in the chrome-nickel alloy wire area. The temperature sensor is more reliable, can be applied to large-range temperature and temperature gradient measurement under complex and severe working conditions such as high temperature, high pressure, closed environment, strong vibration and the like, and can be reconfigured in a temperature measuring interval according to requirements.
The mechanism of the device is as follows: the measurement of the sensing signal is determined according to the time difference relation of the torsional wave signals, the wave speed obtained by calculating the time delay value between the wave crests of the torsional wave at normal temperature accords with a theoretical value, the interval value between the observed wave forms changes along with the temperature, and the measured wave form can be determined to be the required torsional wave signal according to the signal relation; by summarizing the change rule along with the temperature, the wave speed can be considered to change along with the temperature, and the obtained relation accords with a derivation formula of the speed along with the temperature change, so that the measurement is determined to be accurate. The temperature is measured by utilizing the characteristics of slow propagation speed of torsional wave and non-dispersion property of T (0, 1) mode and the propagation speed of torsional wave in the sensitive element material. Compare existing pulse reflection method temperature measurement structure, redesign sensor structure, exert novel magnetostrictive material output signal strong, easy advantage that detects, the reliability is high, propose following improvement: an original signal generator composed of magnetostrictive materials and permanent magnets replaces an ultrasonic transducer to be used as a generating device of guided waves, and the influence of noise signals caused by high temperature and high frequency is reduced; the annular permanent magnet and the detection coil are not in direct contact with the waveguide wire, and only the relative positions of the permanent magnet and the detection coil are fixed and do not change, so that the permanent magnet and the detection coil are not influenced by vibration and have no easily damaged connection points; the chromium-nickel alloy material which is not easy to oxidize at high temperature is adopted, so that the temperature measurement range is expanded.
In the description of the present invention provided herein, it is to be understood that the terms "upper", "lower", "vertical", "horizontal", "top", "bottom", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are only for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.
The invention is not the best known technology.
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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| US4541732A (en) * | 1984-01-27 | 1985-09-17 | General Electric Co. | Ultrasonic temperature sensor |
| CN101140266B (en) * | 2007-10-11 | 2011-01-19 | 华中科技大学 | Device detecting magnetic conduction component defect based on magnetic striction torsion wave |
| US8511144B2 (en) * | 2010-01-11 | 2013-08-20 | General Electric Company | Torsional sensor, method thereof, and system for measurement of fluid parameters |
| CN103837211B (en) * | 2014-03-07 | 2017-02-08 | 河北工业大学 | Fe-Ga material based magnetostriction liquid-level sensor |
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