High-modulus wide-width low-temperature automatic calibration system and calibration method for pressure sensor

Abstract

The invention relates to a pressure sensor calibration system and calibration method, in particular to a high-modulus wide-width low-temperature automatic calibration system and calibration method for a pressure sensor, and solves the problem that the pressure measurement error is large when the existing calibration system is used for calibrating a low-temperature pressure sensor in engine pressure measurement. The system comprises a temperature control module, a liquid nitrogen supply unit, a helium source module, a pressure calibration unit, a high-modulus assembly, a data acquisition and processing module and a control system, the temperature control module comprises a temperature control box, and a liquid nitrogen coil pipe, a micro-channel heat exchanger and a connecting tool which are arranged in the temperature control box; a helium channel and a liquid nitrogen channel are arranged in the micro-channel heat exchanger; a sensor joint communicated with the helium channel is arranged on the connecting tool; a gas cylinder of the helium source module is divided into two paths, the outlet end of a replacement path is communicated with an inner cavity of the temperature control box, and the outlet end of a calibration path is respectively communicated with a standard pressure sensor and the inlet end of a helium channel after passing through a gas collecting pipe and a pressure calibration instrument of the pressure calibration unit; and a vacuum pump of the high-mold assembly is communicated with the helium channel.

Description

Technical Field

[0001] The present invention relates to a pressure sensor calibration system and calibration method, and in particular to a pressure sensor high-module wide-width low-temperature automatic calibration system and calibration method. Background Art

[0002] Cryogenic propellants such as liquid oxygen and methane have become a hot topic in rocket engine development due to their economical, non-toxic, green, and high specific impulse properties. Pressure is a crucial parameter in both early engine development and subsequent flight operations. Under varying temperature conditions, sensors can experience zero-point and sensitivity temperature drift due to the thermal expansion and contraction of their sensitive element materials, internal structure, and manufacturing processes. These drifts are difficult to compensate for over a wide range in conventional sensors, significantly impacting their measurement results.

[0003] However, the vast majority of low-temperature pressure sensors are currently calibrated at room temperature. Only a few with extremely high accuracy requirements are calibrated at low temperatures, a significant departure from the actual operating conditions of the sensors. Statistics show that the impact of sensor temperature performance on test data analysis can result in errors exceeding 10%. Furthermore, existing low-temperature pressure sensor calibration systems have a calibration pressure range of 0 to 40 MPa and only meet the calibration requirements of gauge pressure sensors, not absolute pressure sensors. Engine oxygen pump outlet pressures range from 50 MPa to 60 MPa, and some measurements require absolute pressure sensors, which the existing low-temperature pressure sensor calibration systems fail to cover. Using existing low-temperature pressure sensor calibration systems for pressure sensor calibration in engine fault diagnosis research would increase the probability of misdiagnosis and fail to meet operational requirements.

[0004] Therefore, it is urgent to develop a low-temperature automatic calibration system and calibration method for pressure sensors with a wide calibration pressure range, which can simultaneously meet the calibration requirements of gauge pressure and absolute pressure sensors, and can model the actual operating conditions of pressure sensors in engine pressure measurement with high precision, so as to meet the calibration requirements of low-temperature pressure sensors used for engine pressure measurement, provide calibration data for pressure sensors in different temperature environments, and thus ensure the accuracy of pressure sensor measurements during the early stage of engine development and subsequent actual flight work. Summary of the Invention

[0005] The purpose of the present invention is to solve the technical problems that the existing low-temperature calibration system of pressure sensors has a narrow calibration pressure range, cannot meet the calibration requirements of gauge pressure and absolute pressure sensors at the same time, and the calibration conditions fail to fully cover the actual operating conditions of the pressure sensor in engine pressure measurement, so that after using it for calibration of low-temperature pressure sensors in engine pressure measurement, the pressure measurement error is large and cannot meet the use requirements. A high-module wide-width low-temperature automatic calibration system and calibration method for pressure sensors are provided.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A high-modulus, wide-width, low-temperature automatic calibration system for pressure sensors, which is special in that:

[0008] It includes temperature control module, liquid nitrogen supply unit, helium source module, pressure calibration unit, high-modulus components, data acquisition and processing module and control system;

[0009] The temperature control module includes a temperature control box, a liquid nitrogen coil arranged in the temperature control box, a microchannel heat exchanger and a connecting tool, and also includes a liquid nitrogen exhaust pipe;

[0010] The liquid nitrogen coil is used to cool the ambient temperature in the temperature control box; the microchannel heat exchanger is provided with a mutually independent helium channel and liquid nitrogen channel with both ends open; the connecting tool is provided with N hollow shaft-shaped sensor connectors adapted to the pressure end of the pressure sensor to be calibrated, wherein N is a natural number greater than zero; the inner cavities of the N sensor connectors are all sealed and connected to the helium channel; a temperature sensor for measuring the temperature of the helium is provided in the helium channel; the outlet ends of the liquid nitrogen coil and the liquid nitrogen channel are both connected to the liquid nitrogen exhaust pipe, and the liquid nitrogen is discharged through the liquid nitrogen exhaust pipe;

[0011] The liquid nitrogen supply unit is used to supply liquid nitrogen with controllable flow rate for cooling to the liquid nitrogen coil and the liquid nitrogen channel;

[0012] The helium source module includes a gas cylinder group, a gas supply valve, a calibration path, a replacement path, and a deflation regulating valve; after the gas cylinder group passes through the gas supply valve, it is divided into two paths and communicates with the inlet ends of the calibration path and the replacement path respectively; the calibration path includes a booster pump for supplying high-pressure helium used as a calibration medium to the pressure calibration unit; the outlet end of the replacement path is connected to the inner cavity of the temperature control box, and is used to supply helium for replacing air into the temperature control box; the deflation regulating valve connects the inner cavity of the temperature control box with the outside world, and is used to discharge air when the air in the temperature control box is replaced by helium;

[0013] The pressure calibration unit includes a gas collecting pipe, a pressure calibrator, and a standard pressure sensor; the outlet end of the calibration path passes through the gas collecting pipe and the pressure calibrator in sequence, and then is divided into two paths and communicates with the pressure end of the standard pressure sensor and the inlet end of the helium channel respectively;

[0014] The high-modulus module includes a vacuum pump; a vacuum pump interface of the vacuum pump is connected to the outlet end of the helium channel, and is used to vacuum the helium channel;

[0015] The data acquisition and processing module is used to collect pressure parameters of the pressure sensor to be calibrated and the standard pressure sensor, temperature parameters of each temperature sensor, and vacuum parameters of the helium channel displayed by the pressure calibrator, and transmit the collected parameters to the control system;

[0016] The control system is used to control the components in the data acquisition and processing module, liquid nitrogen supply unit, helium source module, pressure calibration unit, high-mode assembly and temperature control module according to the calibration requirements and / or the parameters collected by the data acquisition and processing module, store the parameters collected by the data acquisition and processing module, and automatically generate original records and calibration certificates for the pressure sensor to be calibrated.

[0017] Furthermore, the booster pump can pressurize the helium to 90 MPa;

[0018] The designed volume of the gas collecting pipe is 0.55L and the working pressure is 90MPa;

[0019] The gas consumption of the pressure calibrator for a single calibration is 35NL.

[0020] With this arrangement, when the helium in the gas collecting pipe reaches 70 MPa, the available helium volume is 110 NL. Therefore, during the calibration test, when the booster pump is not working, the gas collecting pipe can realize three cycles of calibration test operations. Therefore, the gas collecting pipe can ensure the stability of the inlet pressure during the operation of the pressure calibrator. Moreover, during the calibration test, the pressure is maintained above 70 MPa, the calibration step parameters of the pressure sensor are stable, and the calibration process is smooth, which can improve the calibration efficiency, make the sensor calibration curve more stable, and increase the calibration accuracy.

[0021] Furthermore, in order to achieve precise control of the temperature during the calibration test, the liquid nitrogen coil is arranged around the inner wall of the temperature control box;

[0022] The temperature control module further includes a pulse heating belt, a sensor heating belt, a first temperature sensor and a second temperature sensor;

[0023] The pulse heating belt is arranged on the helium channel for local heating to increase the temperature of the helium;

[0024] The sensor heating tape is used to be arranged at the pressure end of the pressure sensor to be calibrated to locally heat it so as to adjust the temperature of the pressure sensor to be calibrated;

[0025] The first temperature sensor and the second temperature sensor are respectively arranged at the inlet end and the outlet end of the helium channel, and are used to measure the helium temperature at the corresponding positions to ensure that the helium temperature at the inlet end and the outlet end of the helium channel are within the target temperature range required by the calibration;

[0026] The pulse heating belt and sensor heating belt are both connected to the control system; the first and second temperature sensors are both connected to the data acquisition and processing module. The control system uses a PID closed-loop control method based on the temperature parameters of the first and second temperature sensors collected by the data acquisition and processing module, using pulse power supply to control the opening and closing of the pulse heating belt and sensor heating belt. By using pulse power supply to control the pulse heating belt, a rapid temperature control response can be achieved, thereby improving the real-time performance of temperature control.

[0027] Furthermore, in order to facilitate the installation of the pressure sensor to be calibrated and the connection of the internal pipes of the temperature control box, the microchannel heat exchanger adopts a microchannel heat exchanger with a printed circuit board heat exchanger structure;

[0028] The N sensor connectors are located on the same plate surface, and the back surface of the plate surface on which the sensor connectors are arranged on the connecting fixture is laid flat on the microchannel heat exchanger and is fixedly connected to the microchannel heat exchanger;

[0029] A helium inlet, a helium outlet, a liquid nitrogen inlet, a liquid nitrogen outlet, a first temperature sensor mounting hole, and a second temperature sensor mounting hole are provided on the plate surface of the connecting fixture where the sensor connector is provided;

[0030] The helium inlet and the helium outlet are sealed and connected to the inlet and outlet of the helium channel respectively; the outlet of the calibration path passes through the gas collecting pipe and the pressure calibrator in sequence, and then connects to the inlet of the helium channel, and is connected to the inlet of the helium channel through the helium inlet; the vacuum pump interface is connected to the outlet of the helium channel through the helium outlet;

[0031] The liquid nitrogen inlet and the liquid nitrogen outlet are sealed and connected to the inlet and outlet of the liquid nitrogen channel respectively; the outlet of the liquid nitrogen channel is connected to the liquid nitrogen exhaust pipe through the liquid nitrogen outlet;

[0032] The positions of the first temperature sensor mounting hole and the second temperature sensor mounting hole correspond to the positions of the inlet end and the outlet end of the helium channel respectively, and are used to mount the first temperature sensor and the second temperature sensor.

[0033] Furthermore, in order to independently and accurately control the liquid nitrogen flow rate supplied to the liquid nitrogen channel and the liquid nitrogen coil, thereby achieving precise temperature control, the liquid nitrogen supply unit includes a liquid nitrogen Dewar, a first cryogenic regulating valve, and a second cryogenic regulating valve;

[0034] The liquid nitrogen dewar supplies liquid nitrogen by self-pressurization;

[0035] The outlet end of the liquid nitrogen dewar is divided into two paths: one path passes through the first low-temperature regulating valve and the liquid nitrogen inlet in sequence and is connected to the inlet end of the liquid nitrogen channel; the other path passes through the second low-temperature regulating valve and is connected to the inlet end of the liquid nitrogen coil.

[0036] Furthermore, the liquid nitrogen supply unit further includes a low-temperature manual valve;

[0037] The outlet end of the liquid nitrogen dewar is divided into two paths after passing through the low-temperature manual valve: one path passes through the first low-temperature regulating valve and the liquid nitrogen inlet in sequence and is connected to the inlet end of the liquid nitrogen channel; the other path passes through the second low-temperature regulating valve and is connected to the inlet end of the liquid nitrogen coil.

[0038] Furthermore, the high-modulus component further includes a vacuum valve;

[0039] The vacuum pump interface is connected to the outlet end of the helium channel through the vacuum valve and the helium outlet in sequence, so as to evacuate the helium channel.

[0040] Furthermore, the calibration circuit further includes a high-pressure gas supply valve and a drive control valve; the booster pump is connected to a process drive gas source through the drive control valve to provide process drive gas for the booster pump;

[0041] The replacement path includes a replacement gas source valve, a replacement pressure reducer, a replacement gas supply valve and a pressure regulating port;

[0042] The gas cylinder group is divided into two paths after passing through the gas source supply valve: one path passes through the booster pump and the high-pressure gas supply valve in sequence, and is connected to the inlet end of the gas collecting pipe, and supplies high-pressure helium used as a calibration medium to the pressure calibration unit; the other path passes through the replacement gas source valve, the replacement pressure reducer, the replacement gas supply valve and the pressure regulating port in sequence, and is connected to the inner cavity of the temperature control box, and supplies helium for replacing air into the temperature control box.

[0043] Furthermore, in order to reduce the influence of impurities in helium on the temperature of the inner cavity of the temperature control box and the calibration results, a gas source filter is provided on the calibration path at a position upstream of the helium supply of the booster pump, and the gas source supply valve is connected to the booster pump through the gas source filter; a high-pressure filter is provided on the calibration path at a position downstream of the helium supply of the high-pressure supply valve, and the high-pressure supply valve is connected to the inlet end of the gas collecting pipe through the high-pressure filter;

[0044] A replacement filter is provided on the replacement path at a position downstream of the helium supply of the replacement gas supply valve, and the replacement gas supply valve is connected to the pressure regulating port through the replacement filter;

[0045] In order to improve the safety of the pipeline, a first pressure gauge and a gas source release valve are sequentially provided on the main pipeline connecting the gas source supply valve with the inlet ends of the calibration path and the replacement path according to the helium flow direction;

[0046] A high-pressure air release valve is provided on the calibration path between the high-pressure air supply valve and the high-pressure filter;

[0047] A second pressure gauge and a safety valve are respectively provided at the inlet and outlet ends of the gas collecting pipe;

[0048] On the replacement path, a fourth pressure gauge and a replacement air release valve are provided between the replacement gas source valve and the replacement pressure reducer, and a third pressure gauge is provided between the replacement pressure reducer and the replacement gas supply valve.

[0049] At the same time, the present invention also provides a high-modulus, wide-width, low-temperature automatic calibration method for a pressure sensor, which is special in that it includes the following steps:

[0050] Step 1: Construct the high-module, wide-width, low-temperature automatic calibration system for the pressure sensor, and make all valves in the system closed. At this time, the temperature control box is at room temperature and atmospheric pressure.

[0051] Step 2: Turn on the control system and data acquisition and processing module in the high-module, wide-width, low-temperature automatic calibration system for pressure sensors constructed in Step 1, with all valves in the closed state; then turn on the power supplies of all valves and instruments and meters in the gas source supply valve, the calibration line, the pressure calibration unit, and the connecting line between the pressure calibration unit and the helium channel, except for the valve for venting; then turn on the gas cylinder assembly and introduce helium into the helium channel to expel air in the pipeline from the sensor connector;

[0052] Step 3: Install the pressure sensor to be calibrated on the sensor connector;

[0053] Step 4: According to the calibration requirements, set the parameters of the booster pump and start the booster pump to boost the pressure of the gas collecting pipe. When the pressure of the gas collecting pipe reaches the working pressure, perform an air tightness test on the pressure sensor to be calibrated installed in step 3. After the air tightness test is passed, close the door of the temperature control box and turn off the booster pump.

[0054] Step 5: Open all valves, instruments, and meters on the replacement path except the valve for venting, and the venting regulating valve, and deliver helium to the inner cavity of the temperature control box to replace the air in the temperature control box with helium. After delivering helium for at least 3 minutes, close all valves, instruments, and meters on the replacement path, as well as the venting regulating valve;

[0055] Step 6: Determine whether the pressure sensor to be calibrated installed in step 3 is an absolute pressure sensor; if so, proceed to step 7; if not, the pressure sensor to be calibrated is a gauge pressure sensor, proceed to step 8;

[0056] Step 7: Start the vacuum pump and open the valve on the connecting pipeline between the vacuum pump's vacuum interface and the outlet end of the helium channel to evacuate the connecting pipeline between the gas cylinder assembly and the inlet end of the calibration line, the calibration line, the pressure calibration unit, and the helium channel. When the vacuum degree of the helium channel displayed by the pressure calibrator reaches the vacuum degree required for calibration, close the vacuum pump and the valve on the connecting pipeline between the vacuum pump's vacuum interface and the outlet end of the helium channel.

[0057] Step 8: Turn on the liquid nitrogen supply unit to supply liquid nitrogen to the liquid nitrogen coil and the liquid nitrogen channel;

[0058] Step 9: According to the calibration requirements, the calibration parameters of the pressure calibrator are set; then the booster pump and the pressure calibrator are started, and the pressure sensor to be calibrated installed in step 3 is subjected to at least three cycles of loading and unloading calibration tests. During the calibration test, the control system communicates with the pressure calibrator, and the pressure parameters of the pressure sensor to be calibrated and the standard pressure sensor and the temperature parameters of each temperature sensor are collected in real time through the data acquisition and processing module. The PID closed-loop control method is used to control the opening, closing and opening size adjustment of each valve in the liquid nitrogen supply unit in real time according to the collected temperature parameters of each temperature sensor, so as to ensure that the temperature of the helium in the helium channel meets the calibration requirements;

[0059] Step 10: The control system automatically generates original records and a calibration certificate for the pressure sensor to be calibrated based on the calibration requirements and the parameters collected by the data acquisition and processing module during the calibration test in step 9;

[0060] Step 11: Turn off the liquid nitrogen supply unit, helium source module and pressure calibration unit, open the door of the temperature control box, allow the temperature control box to return to temperature, remove the pressure sensor to be calibrated installed in step 3, and seal the sensor connector to facilitate the next calibration to complete the calibration.

[0061] The beneficial effects of the present invention are:

[0062] (1) The high-module, wide-width, low-temperature automatic calibration system for pressure sensors of the present invention, first, includes a calibration circuit for supplying calibration medium to the pressure calibration unit, which includes a booster pump. The booster pump can boost the pressure of the calibration medium helium to 90 MPa, thereby realizing high-pressure and large-scale calibration of the pressure sensor to be calibrated; the pressure calibration unit includes a gas collecting pipe, a pressure calibrator, and a standard pressure sensor; the outlet end of the calibration circuit passes through the gas collecting pipe and the pressure calibrator in turn, and is divided into two paths and connected to the pressure end of the standard pressure sensor and the inlet end of the helium channel respectively; the design volume of the gas collecting pipe is 0.55L, the working pressure is 90 MPa, and the gas consumption of the pressure calibrator for a single calibration is 35NL; in this way, the helium in the gas collecting pipe is used When 70 MPa is used, the amount of helium available is 110 NL. Therefore, during the calibration test, when the booster pump is not working, the gas collecting pipe can realize three cycles of calibration test operations, thereby ensuring the stability of the inlet pressure during the operation of the pressure calibrator through the gas collecting pipe; and during the calibration test, the pressure is maintained above 70 MPa, the calibration step parameters of the pressure sensor are stable, the calibration process is smooth, the calibration efficiency can be improved, and the sensor calibration curve can be made more stable, and the calibration accuracy is higher. Therefore, the high-module wide-width low-temperature automatic calibration system for pressure sensors of the present invention can achieve accurate calibration in the calibration pressure range of 0 MPa to 70 MPa.

[0063] Secondly, the high-module, wide-width, low-temperature automatic calibration system for pressure sensors of the present invention includes a high-module assembly, which includes a vacuum pump. The vacuum pump's vacuum interface is connected to the outlet end of the helium channel, capable of evacuating the helium channel to achieve high-module environment simulation of the vacuum degree. Therefore, the high-module, wide-width, low-temperature automatic calibration system for pressure sensors of the present invention can meet the calibration requirements of not only gauge pressure sensors, but also absolute pressure sensors.

[0064] Furthermore, in the high-modulus, wide-width, low-temperature automatic calibration system for pressure sensors of the present invention, a low-temperature environment is simulated by a temperature control box and a liquid nitrogen supply unit. The temperature control box is insulated; the liquid nitrogen supply unit supplies liquid nitrogen for cooling with a controllable flow rate to the liquid nitrogen coil and liquid nitrogen channel. The liquid nitrogen coil cools the ambient temperature within the temperature control box, and the liquid nitrogen channel cools the high-pressure helium used as the calibration medium. Therefore, the high-modulus, wide-width, low-temperature automatic calibration system for pressure sensors of the present invention can not only achieve accurate calibration in the low-temperature range of 77K to 113K, but also meet calibration requirements over a wide temperature range of 77K to 293K (room temperature). Moreover, the entire calibration process can be completed automatically.

[0065] To sum up, the high-modulus, wide-width, low-temperature automatic calibration system for pressure sensors of the present invention provides calibration conditions that can fully cover the actual operating conditions of pressure sensors in engine pressure measurement. When it is used for the calibration of low-temperature pressure sensors in engine pressure measurement, it can achieve high-precision calibration, thereby effectively improving the accuracy and reliability of pressure measurement. Therefore, the present invention solves the technical problems that the existing low-temperature calibration system for pressure sensors has a narrow calibration pressure range, cannot simultaneously meet the calibration requirements of gauge pressure and absolute pressure sensors, and the calibration conditions fail to fully cover the actual operating conditions of pressure sensors in engine pressure measurement, so that after it is used for the calibration of low-temperature pressure sensors in engine pressure measurement, the pressure measurement error is large and cannot meet the use requirements.

[0066] (2) The high-module wide-width low-temperature automatic calibration system for the pressure sensor of the present invention preferably includes a temperature control module further comprising a pulse heating belt, a sensor heating belt, a first temperature sensor and a second temperature sensor; and the control system adopts a PID closed-loop control method according to the temperature parameters of the first temperature sensor and the second temperature sensor acquired by the data acquisition and processing module, and uses pulse power supply to control the opening and closing of the pulse heating belt and the sensor heating belt; thus, during the calibration test, the temperature of the helium channel and the inner cavity of the temperature control box can be first lowered to a target temperature value lower than the calibration requirement by the liquid nitrogen supply unit, thereby achieving a rough adjustment of the temperature; and then, on the one hand, the helium channel is locally heated by the pulse heating belt, so that the temperature of the helium used as the calibration medium rises and enters the calibration requirement. When the target temperature range is reached, heating is stopped; then the helium exchanges heat with the liquid nitrogen in the surrounding liquid nitrogen channel, the temperature drops again, the pulse heating belt starts working again, and the temperature rises again, and this process is repeated to ensure that the helium temperature in the helium channel is always within the target temperature range required for calibration, thereby achieving fine adjustment and precise control of the helium temperature, which effectively overcomes the problem of large thermal inertia of liquid nitrogen and poor control accuracy; on the other hand, the same is true for the sensor heating belt, which locally heats the pressure sensor to be calibrated through the sensor heating belt to achieve fine adjustment and precise control of the external ambient temperature of the pressure sensor to be calibrated; therefore, the high-module wide-width low-temperature automatic calibration system for pressure sensors of the present invention can achieve precise control of temperature, and thus can achieve precise calibration under specific temperature conditions. In addition, after the calibration is completed, by adjusting the heating power of the pulse heating belt and the sensor heating belt to the maximum, the temperature in the temperature control box can also be quickly restored to normal temperature.

[0067] (3) The temperature control module of the high-module, wide-width, low-temperature automatic calibration system for pressure sensors of the present invention includes a connecting tool, on which N hollow shaft-shaped sensor connectors adapted to the pressure ends of the pressure sensors to be calibrated are provided, where N is a natural number greater than zero; this not only facilitates the installation of the pressure sensors to be calibrated, but also allows calibration of multiple pressure sensors to be calibrated at one time; at the same time, in the high-module, wide-width, low-temperature automatic calibration system for pressure sensors of the present invention, preferably, the N sensor connectors are located on the same plate surface, and the back surface of the plate surface on which the sensor connectors are provided on the connecting tool is flatly laid on the microchannel heat exchanger and fixedly connected to the microchannel heat exchanger; a helium inlet, a helium outlet, a liquid nitrogen inlet, a liquid nitrogen outlet, a first temperature sensor mounting hole, and a second temperature sensor mounting hole are provided on the plate surface on which the sensor connectors are provided on the connecting tool; this arrangement not only facilitates the cooling of the high-pressure helium used as the calibration medium, but also facilitates the connection of the internal pipelines of the temperature control box.

[0068] (4) The high-module, wide-width, low-temperature automatic calibration system for pressure sensors of the present invention, wherein the helium source module thereof further comprises a replacement path and a venting regulating valve; the outlet end of the replacement path is connected to the inner cavity of the temperature control box, and is used to supply helium for replacing air into the temperature control box; the venting regulating valve connects the inner cavity of the temperature control box with the outside, and is used to discharge air when the air in the inner cavity of the temperature control box is replaced with helium; by replacing the air in the inner cavity of the temperature control box with helium through the replacement path and the venting regulating valve, the dew point of the gas in the inner cavity of the temperature control box can be ensured to be low, and the condensation and freezing of moisture in the air in the inner cavity of the temperature control box can be avoided; at the same time, replacing the air with helium can also reduce temperature fluctuations, making the temperature more stable during the calibration test and the calibration results more accurate, thereby also improving the accuracy of the subsequent pressure measurement.

[0069] (5) The high-modulus, wide-width, low-temperature automatic calibration system for pressure sensors of the present invention uses helium as the calibration medium and liquid nitrogen to provide a low-temperature environment. Helium is in a high-pressure, low-temperature state, while liquid nitrogen is in a low-temperature, low-pressure state. High-pressure calibration can be achieved by using helium, and through structural design and utilizing the fluidity of the gas, the consistency of pressure at the position of the standard pressure sensor and the pressure sensor to be calibrated is ensured.

[0070] (6) The high-module, wide-width, low-temperature automatic calibration system and calibration method of the pressure sensor of the present invention can automatically calibrate gauge pressure and absolute pressure sensors under different temperatures, pressures and vacuum levels; by calibrating the full range of high-precision standard pressure sensors under standard working conditions, the measurement errors of the pressure sensors put into the test caused by temperature and vacuum level can be corrected; through online automatic calibration, the calibration labor intensity is effectively reduced, the calibration efficiency is improved, and it is possible to calibrate the pressure sensor before and after the test. It can meet the demand for low-temperature calibration of pressure sensors, can provide calibration data under different temperature environments, and ensure the accuracy and reliability of pressure sensor measurements in low-temperature environments during engine flight and testing. After its completion, it also lays the foundation for low-temperature calibration research of other types of heavy-duty carrier engine products.

[0071] (7) The high-modulus, wide-width, low-temperature automatic calibration system and calibration method of the pressure sensor of the present invention are used to calibrate the pressure sensor, which can compensate for the zero-point temperature drift and sensitivity temperature drift of the pressure sensor, improve the accuracy of data acquisition, eliminate problematic sensors with large test accuracy deviations in temperature and high-modulus environments, improve the reliability, accuracy and credibility of data acquisition, reduce the impact of errors, improve measurement accuracy, and have a positive effect on the stable, accurate and efficient testing of pressure parameters. Pressure sensors are widely used in science and technology, industrial control, aerospace, biomedicine, petrochemical industry, automobiles, heavy machinery and other fields. Therefore, the high-modulus, wide-width, low-temperature automatic calibration system and calibration method of the pressure sensor of the present invention have good application prospects and have technical characteristics for large-scale promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Figure 1 This is a schematic diagram of the structural principle of an embodiment of a high-modulus, wide-width, low-temperature automatic calibration system for pressure sensors according to the present invention;

[0073] Figure 2 This is a structural diagram of the temperature control module in an embodiment of the high-module wide-width low-temperature automatic calibration system for pressure sensors of the present invention (the figure also includes high-module components).

[0074] The descriptions of the numbers in the figure are as follows:

[0075] 1-gas cylinder group, 2-first pressure gauge, 3-gas supply valve, 4-gas release valve, 5-gas filter, 6-drive control valve, 7-boost pump, 8-replacement gas source valve, 9-high-pressure supply valve, 10-high-pressure release valve, 11-high-pressure filter, 12-second pressure gauge, 13-gas collecting pipe, 14-safety valve, 15-pressure calibrator, 16-standard pressure sensor, 17-pressure regulating port, 18-liquid nitrogen exhaust pipe, 19-vacuum pump, 20-vacuum valve, 21-first low-temperature regulating valve, 22-second Second low-temperature regulating valve, 23-air release regulating valve, 24-low-temperature manual valve, 25-liquid nitrogen Dewar, 26-replacement filter, 27-replacement air supply valve, 28-replacement air release valve, 29-third pressure gauge, 30-replacement pressure reducer, 31-fourth pressure gauge, 32-temperature control box, 33-liquid nitrogen coil, 34-pulse heating belt, 35-microchannel heat exchanger, 36-sensor heating belt, 37-helium channel, 38-liquid nitrogen channel, 39-first temperature sensor, 40-sensor connector, 41-second temperature sensor. DETAILED DESCRIPTION

[0076] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0077] See also Figure 1 The present invention provides a high-modulus, wide-width, low-temperature automatic calibration system for a pressure sensor, including a temperature control module, a liquid nitrogen supply unit, a helium source module, a pressure calibration unit, a high-modulus component, a data acquisition and processing module, and a control system.

[0078] See also Figure 1 and Figure 2 The temperature control module includes a temperature control box 32 , a liquid nitrogen coil 33 arranged in the temperature control box 32 , a microchannel heat exchanger 35 and a connecting tool, and also includes a liquid nitrogen exhaust pipe 18 .

[0079] See also Figure 1 and Figure 2The liquid nitrogen coil 33 is used to cool the ambient temperature within the temperature control box 32. In this embodiment, for better cooling effect, the liquid nitrogen coil 33 is preferably arranged around the inner wall of the temperature control box 32. The microchannel heat exchanger 35 is provided with a mutually independent helium channel 37 and liquid nitrogen channel 38 with open ends. The liquid nitrogen flowing through the liquid nitrogen channel 38 is used to cool the helium used as the calibration medium in the helium channel 37, and while achieving the cooling effect, it also isolates the high pressure of the helium from the low pressure of the liquid nitrogen. In this embodiment, for better heat exchange effect, the microchannel heat exchanger 35 is preferably a microchannel heat exchanger with a printed circuit board heat exchanger structure. In order to accurately control the temperature of the helium in the helium channel 37 during calibration testing, a first temperature sensor 39 and a second temperature sensor 41 are preferably provided at the inlet and outlet of the helium channel 37, respectively, for measuring the helium temperature at the corresponding positions to ensure that the helium temperature at the inlet and outlet of the helium channel 37 is within the target temperature range required for calibration. The above-mentioned connecting fixture is provided with N hollow shaft-shaped sensor connectors 40 adapted to the pressure end of the pressure sensor to be calibrated, where N is a natural number greater than zero; the inner cavities of the N sensor connectors 40 are all sealed and connected to the helium channel 37; in this embodiment, the above-mentioned N is equal to 6; the above-mentioned pressure sensor to be calibrated and the sensor connector 40 are connected in a threaded manner, and the calibration medium helium is delivered to the pressure end of the pressure sensor to be calibrated through the helium channel 37 and the sensor connector 40; and in this embodiment, in order to facilitate the connection of the internal pipelines of the temperature control box, it is preferred that the N sensor connectors 40 are located on the same plate surface, and the back surface of the plate surface on which the sensor connector 40 is provided on the connecting fixture is flattened on the microchannel heat exchanger 35, and is fixedly connected to the microchannel heat exchanger 35, and is fixedly connected to the microchannel heat exchanger 35. The heat exchanger 35 is installed on the door of the temperature control box 32 together; on the plate surface where the sensor connector 40 is provided on the connecting tool, a helium inlet, a helium outlet, a liquid nitrogen inlet, a liquid nitrogen outlet, a first temperature sensor mounting hole and a second temperature sensor mounting hole are provided; the above-mentioned helium inlet and helium outlet are respectively and correspondingly connected to the inlet end and outlet end of the above-mentioned helium channel 37 in a sealed manner; the above-mentioned liquid nitrogen inlet and liquid nitrogen outlet are respectively and correspondingly connected to the inlet end and outlet end of the above-mentioned liquid nitrogen channel 38 in a sealed manner; the positions of the above-mentioned first temperature sensor mounting hole and the second temperature sensor mounting hole correspond to the positions of the inlet end and outlet end of the above-mentioned helium channel 37, respectively, for mounting the above-mentioned first temperature sensor 39 and second temperature sensor 41. The outlet ends of the liquid nitrogen coil 33 and the liquid nitrogen channel 38 are both connected to the liquid nitrogen exhaust pipe 18. In this embodiment, the outlet end of the liquid nitrogen channel 38 is connected to the liquid nitrogen exhaust pipe 18 through the liquid nitrogen outlet, and the liquid nitrogen in the liquid nitrogen coil 33 and the liquid nitrogen channel 38 is discharged through the liquid nitrogen exhaust pipe 18.

[0080] See also Figure 2In order to achieve precise control of the helium temperature in the helium channel 37 and the ambient temperature of the pressure sensor to be calibrated, in this embodiment, the above-mentioned temperature control module preferably also includes a pulse heating belt 34 and a sensor heating belt 36; the pulse heating belt 34 is arranged on the helium channel 37 for local heating to increase the helium temperature; the sensor heating belt 36 is used to be arranged on the pressure end of the pressure sensor to be calibrated to locally heat it to achieve temperature adjustment of the pressure sensor to be calibrated; the pulse heating belt 34 and the sensor heating belt 36 are both connected to the control system; the above-mentioned first temperature sensor 39 and second temperature sensor 41 are both connected to the data acquisition and processing module; the control system adopts PID closed-loop control according to the temperature parameters of the first temperature sensor 39 and the second temperature sensor 41 collected by the data acquisition and processing module, and uses pulse power supply to control the opening and closing of the pulse heating belt 34 and the sensor heating belt 36 to achieve rapid response of temperature control and precise temperature adjustment.

[0081] See also Figure 1 and Figure 2 The liquid nitrogen supply unit is used to supply a controllable flow of liquid nitrogen for cooling the liquid nitrogen coil 33 and liquid nitrogen channel 38. In this embodiment, the liquid nitrogen supply unit preferably includes a liquid nitrogen dewar 25, a cryogenic manual valve 24, a first cryogenic regulating valve 21, and a second cryogenic regulating valve 22. The liquid nitrogen dewar 25 supplies liquid nitrogen through self-pressurization. The outlet of the liquid nitrogen dewar 25 passes through the cryogenic manual valve 24 and splits into two paths: one path passes through the first cryogenic regulating valve 21 and the liquid nitrogen inlet, connecting to the inlet of the liquid nitrogen channel 38; the other path passes through the second cryogenic regulating valve 22 and connects to the inlet of the liquid nitrogen coil 33. By adjusting the openings of the first and second cryogenic regulating valves 21 and 22, the liquid nitrogen supply flow rate can be adjusted, thereby achieving control of the cooling rate and precise temperature regulation. In this embodiment, the cryogenic manual valve 24 is provided solely to facilitate manual control of the liquid nitrogen supply and may be omitted.

[0082] See also Figure 1 The helium source module includes a gas cylinder group 1, a gas supply valve 3, a calibration path, a replacement path, and a bleed regulating valve 23. After the gas cylinder group 1 passes through the gas supply valve 3, it is divided into two paths and connected to the inlet ends of the calibration path and the replacement path respectively. The calibration path includes a booster pump 7 for supplying high-pressure helium as a calibration medium to the pressure calibration unit. The outlet end of the replacement path is connected to the inner cavity of the temperature control box 32 for supplying helium for replacing air into the temperature control box 32. The bleed regulating valve 23 connects the inner cavity of the temperature control box 32 with the outside world and is used to discharge air when the air in the temperature control box 32 is replaced by helium. Figure 1In this embodiment, the calibration circuit preferably also includes a high-pressure gas supply valve 9 and a drive control valve 6. The booster pump 7 is connected to the process drive gas source through the drive control valve 6 to provide process drive gas to the booster pump 7. The replacement circuit preferably includes a replacement gas source valve 8, a replacement pressure reducer 30, a replacement gas supply valve 27, and a pressure regulating port 17. After passing through the gas source supply valve 3, the gas cylinder assembly 1 is divided into two paths: one path passes through the booster pump 7 and the high-pressure gas supply valve 9 in sequence, and then connects to the inlet end of the gas manifold 13, supplying high-pressure helium gas used as the calibration medium to the pressure calibration unit; the other path passes through the replacement gas source valve 8, the replacement pressure reducer 30, the replacement gas supply valve 27, and the pressure regulating port 17 in sequence, and then connects to the inner cavity of the temperature control box 32, supplying helium gas for replacement air into the temperature control box 32. After calibration, ambient temperature gas is purged through the pressure regulating port 17, which can quickly return the temperature of the temperature control box 32 to the normal temperature, preparing for the next round of calibration testing and improving calibration efficiency.

[0083] See also Figure 1 In order to reduce the influence of impurities in helium on the temperature in the temperature control box and the calibration results, in this embodiment, a gas source filter 5 is preferably provided on the calibration path at the upstream position of the helium supply of the booster pump 7, and the above-mentioned gas source supply valve 3 is connected to the booster pump 7 through the gas source filter 5; a high-pressure filter 11 is provided on the calibration path at the downstream position of the helium supply of the high-pressure supply valve 9, and the high-pressure supply valve 9 is connected to the inlet end of the gas collecting pipe 13 through the high-pressure filter 11; a replacement filter 26 is provided on the replacement path at the downstream position of the helium supply of the replacement supply valve 27, and the replacement supply valve 27 is connected to the pressure regulating port 17 through the replacement filter 26. In order to facilitate the observation of the pressure at different positions of the pipeline and improve the safety of the pipeline, in this embodiment, preferably, on the main pipeline connecting the above-mentioned gas source supply valve 3 with the inlet end of the above-mentioned calibration path and the replacement path, a first pressure gauge 2 and a gas source release valve 4 are arranged in sequence according to the helium flow direction; a high-pressure release valve 10 is arranged at a position between the high-pressure supply valve 9 and the high-pressure filter 11 on the above-mentioned calibration path; a second pressure gauge 12 and a safety valve 14 are respectively arranged at the inlet and outlet ends of the above-mentioned gas collecting pipe 13; on the above-mentioned replacement path, a fourth pressure gauge 31 and a replacement release valve 28 are arranged between the replacement gas source valve 8 and the replacement pressure reducer 30, and a third pressure gauge 29 is arranged between the replacement pressure reducer 30 and the replacement supply valve 27.

[0084] See also Figure 1The pressure calibration unit includes a gas manifold 13, a pressure calibrator 15, and a standard pressure sensor 16. The outlet of the calibration path passes through the gas manifold 13 and the pressure calibrator 15, then splits into two paths, connecting to the pressure end of the standard pressure sensor 16 and the inlet of the helium channel 37. The pressure calibration unit can perform full-scale graded calibration of the pressure sensor to be calibrated, setting the number of calibration pressure steps and step pressure values within the full range, and automatically loading, unloading, and cyclically calibrating helium. The pressure calibrator 15 implements PID closed-loop control of the pressure calibration step points through pressurization and unloading, ensuring absolute stability of the calibration pressure within 10 seconds and consistent pressure values at all points in the pipeline. The standard pressure sensor 16 is located in a standard operating environment at room temperature and has an accuracy of 0.1%. It can be range-switched based on the range of the pressure sensor to be calibrated. Calibration accuracy can be improved when the range of the configured standard pressure sensor 16 is close to that of the pressure sensor to be calibrated. PID closed-loop control of the pressure calibration point between the standard pressure sensor 16 and the pressure calibrator 15 ensures high-precision pressure calibration step control. In this embodiment, to facilitate pipeline connection, the outlet of the calibration line passes through the gas manifold 13 and the pressure calibrator 15, and then connects to the inlet of the helium channel 37. This line is connected to the inlet of the helium channel 37 via the helium inlet. In this embodiment, the booster pump 7 can boost the helium to 90 MPa, the gas collecting pipe 13 has a design volume of 0.55 L, a working pressure of 90 MPa, and the pressure calibrator 15 consumes 35 NL for a single calibration. In this way, when the helium in the gas collecting pipe reaches 70 MPa, the available helium amount is 110 NL. Therefore, during the calibration test, when the booster pump is not working, the gas collecting pipe can realize three cycles of calibration test operations, so that the gas collecting pipe can ensure the stability of the inlet pressure during the operation of the pressure calibrator. Moreover, during the calibration test, the pressure is maintained above 70 MPa, the calibration step parameters of the pressure sensor are stable, and the calibration process is smooth, which can improve the calibration efficiency, and also make the sensor calibration curve more stable and the calibration accuracy higher. Therefore, the high-modulus, wide-width, low-temperature automatic calibration system for pressure sensors of the present invention can realize accurate calibration in the calibration pressure range of 0 MPa to 70 MPa.

[0085] See also Figure 1 and Figure 2The high-modulus module assembly includes a vacuum pump 19; the vacuum pump 19's vacuum port is connected to the outlet of the helium channel 37, used to evacuate the helium channel 37 to achieve high-precision modeling of the actual operating environment of the pressure sensor to be calibrated. In this embodiment, the high-modulus module assembly preferably also includes a vacuum valve 20; the vacuum pump 19's vacuum port is connected to the outlet of the helium channel 37 through the vacuum valve 20 and the helium outlet. The vacuum pump 19 and vacuum valve 20 can adjust the pressure within the helium channel 37 to achieve a vacuum level within the range of 2 Pa to 100 kPa (absolute pressure), thereby achieving the goal of calibrating the pressure sensor to be calibrated simultaneously with the vacuum operating environment.

[0086] The data acquisition and processing module is used to collect the pressure parameters of the pressure sensor to be calibrated and the standard pressure sensor 16, the temperature parameters of each temperature sensor, and the vacuum parameter of the helium channel 37 displayed by the pressure calibrator 15, and transmit the collected parameters to the control system;

[0087] The control system is used to control the components of the data acquisition and processing module, liquid nitrogen supply unit, helium source module, pressure calibration unit, high-pressure module assembly, and temperature control module based on calibration requirements and / or parameters collected by the data acquisition and processing module. It also stores the parameters collected by the data acquisition and processing module and automatically generates original records and a calibration certificate for the pressure sensor to be calibrated. In this embodiment, the calibration certificate generated by the control system includes parameters such as the accuracy, linearity, slope, and intercept of the pressure sensor to be calibrated.

[0088] In addition, the present invention also provides a high-modulus, wide-width, low-temperature automatic calibration method for a pressure sensor, comprising the following steps:

[0089] Step 1: Construct the high-module, wide-width, low-temperature automatic calibration system for the pressure sensor, and set all valves in the system to the closed state. At this time, the temperature control box 32 is at room temperature and atmospheric pressure.

[0090] Step 2: Turn on the control system and data acquisition and processing module in the high-modulus, wide-width, low-temperature automatic calibration system for pressure sensors constructed in Step 1, with all valves in the closed state. Then, turn on the power supplies of all valves, instruments, and meters in the pipeline connecting the pressure calibration unit and the helium channel 37, except for the valve for venting. Then, turn on the gas cylinder assembly 1 and introduce helium into the helium channel 37 to expel air from the pipeline through the sensor connector 40.

[0091] Step 3: Install the pressure sensor to be calibrated on the sensor connector 40;

[0092] Step 4: According to the calibration requirements, set the parameters of the booster pump 7 and start the booster pump 7 to boost the pressure of the gas collecting pipe 13. When the pressure of the gas collecting pipe 13 reaches the working pressure, perform an air tightness test on the pressure sensor to be calibrated installed in step 3. After the air tightness test is passed, close the door of the temperature control box 32 and turn off the booster pump 7.

[0093] Step 5: Open all valves, instruments, and meters on the replacement path except the valve for venting, as well as the venting regulating valve 23, and deliver helium to the inner cavity of the temperature control box 32 to replace the air in the temperature control box 32 with helium. After delivering helium for at least 3 minutes, close all valves, instruments, and meters on the replacement path, as well as the venting regulating valve 23;

[0094] Step 6: Determine whether the pressure sensor to be calibrated installed in step 3 is an absolute pressure sensor; if so, proceed to step 7; if not, the pressure sensor to be calibrated is a gauge pressure sensor, proceed to step 8;

[0095] Step 7: Start the vacuum pump 19 and open the valve on the connecting pipe between the vacuum pump interface of the vacuum pump 19 and the outlet end of the above-mentioned helium channel 37 to evacuate the connecting pipe between the gas cylinder group 1 and the inlet end of the calibration line, the calibration line, the pressure calibration unit and the above-mentioned helium channel 37. When the vacuum degree of the above-mentioned helium channel 37 displayed by the pressure calibrator 15 reaches the vacuum degree required for calibration, close the vacuum pump 19 and the valve on the connecting pipe between the vacuum pump interface of the vacuum pump 19 and the outlet end of the above-mentioned helium channel 37. In this embodiment, the pressure sensor to be calibrated is an absolute pressure sensor, and the pressure is evacuated to an absolute vacuum pressure of 200Pa±10Pa.

[0096] Step 8: Turn on the liquid nitrogen supply unit to supply liquid nitrogen to the liquid nitrogen coil 33 and the liquid nitrogen channel 38;

[0097] Step 9: According to the calibration requirements, the calibration parameters of the pressure calibrator 15 are set; then the booster pump 7 and the pressure calibrator 15 are started, and the pressure sensor to be calibrated installed in step 3 is subjected to at least three cycles of loading and unloading calibration tests. During the calibration test, the control system communicates with the pressure calibrator 15, and the pressure parameters of the pressure sensor to be calibrated and the standard pressure sensor 16 and the temperature parameters of each temperature sensor are collected in real time through the data acquisition and processing module. The PID closed-loop control method is used to control the opening, closing and opening size adjustment of each valve in the liquid nitrogen supply unit in real time according to the collected temperature parameters of each temperature sensor to ensure that the temperature of the helium in the helium channel 37 meets the calibration requirements. In this embodiment, the temperature of the helium in the helium channel 37 is controlled within the range of 90K±5K (-183℃±5℃);

[0098] Step 10: The control system automatically generates original records and a calibration certificate for the pressure sensor to be calibrated based on the calibration requirements and the parameters collected by the data acquisition and processing module during the calibration test in Step 9. In this embodiment, the calibration certificate generated by the control system includes parameters such as the accuracy, linearity, slope, and intercept of the pressure sensor to be calibrated.

[0099] Step 11: Turn off the liquid nitrogen supply unit, helium source module and pressure calibration unit, open the door of the temperature control box 32, allow the temperature control box 32 to return to temperature, remove the pressure sensor to be calibrated installed in step 3, and seal the sensor connector 40 for use in the next calibration to complete the calibration.

[0100] In summary, the high-modulus, wide-width, low-temperature automatic calibration system and calibration method of the pressure sensor of the present invention can automatically calibrate gauge pressure and absolute pressure sensors under different temperatures, pressures and vacuum degrees; through full-scale segmented calibration with high-precision standard pressure sensors under standard working environments, the measurement errors of the pressure sensors put into the test caused by temperature and vacuum degree are corrected; through online automatic calibration, the calibration labor intensity is effectively reduced, the calibration efficiency is improved, and it becomes possible to calibrate the pressure sensor before and after the test. It can meet the needs of low-temperature calibration of pressure sensors, can provide calibration data under different temperature environments, and ensure the accuracy and reliability of pressure sensor measurements in low-temperature environments during engine flight and testing. After its completion, it will also lay the foundation for low-temperature calibration research of other types of heavy-duty carrier engine products.

Claims

1. A high-modulus, wide-width, low-temperature automatic calibration system for pressure sensors, characterized by: It includes temperature control module, liquid nitrogen supply unit, helium source module, pressure calibration unit, high-modulus components, data acquisition and processing module and control system; The temperature control module includes a temperature control box (32), a liquid nitrogen coil (33) arranged in the temperature control box (32), a microchannel heat exchanger (35) and a connecting tool, and also includes a liquid nitrogen exhaust pipe (18); The liquid nitrogen coil (33) is used to cool the ambient temperature in the temperature control box (32); the microchannel heat exchanger (35) is provided with a mutually independent helium channel (37) and a liquid nitrogen channel (38) with both ends open; the connecting tool is provided with N hollow shaft-shaped sensor connectors (40) adapted to the pressure end of the pressure sensor to be calibrated, and N is a natural number greater than zero; the inner cavities of the N sensor connectors (40) are all sealed and connected to the helium channel (37); a temperature sensor for measuring the temperature of helium is provided in the helium channel (37); the outlet ends of the liquid nitrogen coil (33) and the liquid nitrogen channel (38) are both connected to the liquid nitrogen exhaust pipe (18), and the liquid nitrogen is discharged through the liquid nitrogen exhaust pipe (18); The liquid nitrogen supply unit is used to supply liquid nitrogen with controllable flow rate for cooling to the liquid nitrogen coil (33) and the liquid nitrogen channel (38); The helium source module comprises a gas cylinder group (1), a gas source supply valve (3), a calibration path, a replacement path and a deflation regulating valve (23); after the gas cylinder group (1) passes through the gas source supply valve (3), it is divided into two paths and communicated with the inlet ends of the calibration path and the replacement path respectively; the calibration path comprises a booster pump (7) for supplying high-pressure helium as a calibration medium to the pressure calibration unit; the outlet end of the replacement path is communicated with the inner cavity of the temperature control box (32) for supplying helium for replacing air into the temperature control box (32); the deflation regulating valve (23) connects the inner cavity of the temperature control box (32) with the outside world and is used to discharge air when the air in the inner cavity of the temperature control box (32) is replaced by helium; The pressure calibration unit comprises a gas collecting pipe (13), a pressure calibrator (15), and a standard pressure sensor (16); the outlet end of the calibration path passes through the gas collecting pipe (13) and the pressure calibrator (15) in sequence, and then is divided into two paths and communicates with the pressure end of the standard pressure sensor (16) and the inlet end of the helium channel (37) respectively; The high-mode assembly includes a vacuum pump (19); a vacuum pump interface of the vacuum pump (19) is connected to the outlet end of the helium channel (37) for vacuuming the inside of the helium channel (37); The data acquisition and processing module is used to acquire pressure parameters of the pressure sensor to be calibrated and the standard pressure sensor (16), temperature parameters of each temperature sensor, and vacuum parameters of the helium channel (37) displayed by the pressure calibrator (15), and transmit the acquired parameters to the control system; The control system is used to control the components in the data acquisition and processing module, liquid nitrogen supply unit, helium source module, pressure calibration unit, high-mode assembly and temperature control module according to the calibration requirements and / or the parameters collected by the data acquisition and processing module, store the parameters collected by the data acquisition and processing module, and automatically generate original records and calibration certificates for the pressure sensor to be calibrated.

2. The high-modulus, wide-width, low-temperature automatic calibration system for pressure sensors according to claim 1, characterized in that: The booster pump (7) can boost the helium pressure to 90 MPa; The designed volume of the gas collecting pipe (13) is 0.55L and the working pressure is 90MPa; The gas consumption of the pressure calibrator (15) for a single calibration is 35NL.

3. The high-modulus, wide-width, low-temperature automatic calibration system for pressure sensors according to claim 1 or 2, characterized in that: The liquid nitrogen coil (33) is arranged around the inner wall of the temperature control box (32); The temperature control module further includes a pulse heating belt (34), a sensor heating belt (36), a first temperature sensor (39) and a second temperature sensor (41); The pulse heating belt (34) is arranged on the helium channel (37) for local heating to increase the temperature of the helium; The sensor heating belt (36) is used to be arranged at the pressure end of the pressure sensor to be calibrated, and locally heats the pressure end to achieve temperature regulation of the pressure sensor to be calibrated; The first temperature sensor (39) and the second temperature sensor (41) are respectively arranged at the inlet end and the outlet end of the helium channel (37), and are used to measure the helium temperature at the corresponding positions to ensure that the helium temperature at the inlet end and the outlet end of the helium channel (37) are within the target temperature range required by the calibration; The pulse heating belt (34) and the sensor heating belt (36) are both connected to the control system; the first temperature sensor (39) and the second temperature sensor (41) are both connected to the data acquisition and processing module; the control system adopts a PID closed-loop control method based on the temperature parameters of the first temperature sensor (39) and the second temperature sensor (41) collected by the data acquisition and processing module, and uses pulse power supply to control the opening and closing of the pulse heating belt (34) and the sensor heating belt (36).

4. The high-modulus, wide-width, low-temperature automatic calibration system for pressure sensors according to claim 3 is characterized by: The microchannel heat exchanger (35) adopts a microchannel heat exchanger with a printed circuit board type heat exchanger structure; N sensor connectors (40) are located on the same plate surface, and the back surface of the plate surface on which the sensor connectors (40) are arranged on the connecting tool is laid flat on the microchannel heat exchanger (35) and is fixedly connected to the microchannel heat exchanger (35); A helium inlet, a helium outlet, a liquid nitrogen inlet, a liquid nitrogen outlet, a first temperature sensor mounting hole, and a second temperature sensor mounting hole are provided on a plate surface of the connecting fixture on which the sensor connector (40) is provided; The helium inlet and the helium outlet are sealed and connected to the inlet and outlet of the helium channel (37) respectively; the outlet of the calibration path passes through the gas collecting pipe (13) and the pressure calibrator (15) in sequence, and is connected to the inlet of the helium channel (37) through the helium inlet; the vacuum port of the vacuum pump (19) is connected to the outlet of the helium channel (37) through the helium outlet; The liquid nitrogen inlet and the liquid nitrogen outlet are sealed and communicated with the inlet and outlet of the liquid nitrogen channel (38) respectively; the outlet of the liquid nitrogen channel (38) is communicated with the liquid nitrogen exhaust pipe (18) through the liquid nitrogen outlet; The positions of the first temperature sensor mounting hole and the second temperature sensor mounting hole correspond to the positions of the inlet end and the outlet end of the helium channel (37), respectively, and are used to mount the first temperature sensor (39) and the second temperature sensor (41).

5. The high-modulus, wide-width, low-temperature automatic calibration system for pressure sensors according to claim 4 is characterized in that: The liquid nitrogen supply unit comprises a liquid nitrogen Dewar (25), a first low-temperature regulating valve (21) and a second low-temperature regulating valve (22); The liquid nitrogen dewar (25) supplies liquid nitrogen by self-pressurization; The outlet end of the liquid nitrogen dewar (25) is divided into two paths: one path passes through the first low-temperature regulating valve (21) and the liquid nitrogen inlet in sequence and is connected to the inlet end of the liquid nitrogen channel (38); the other path passes through the second low-temperature regulating valve (22) and is connected to the inlet end of the liquid nitrogen coil (33).

6. The high-modulus, wide-width, low-temperature automatic calibration system for pressure sensors according to claim 5, characterized in that: The liquid nitrogen supply unit further includes a low-temperature manual valve (24); The outlet of the liquid nitrogen dewar (25) is divided into two paths after passing through the low-temperature manual valve (24): one path passes through the first low-temperature regulating valve (21) and the liquid nitrogen inlet in sequence and is connected to the inlet end of the liquid nitrogen channel (38); the other path passes through the second low-temperature regulating valve (22) and is connected to the inlet end of the liquid nitrogen coil (33).

7. The high-modulus, wide-width, low-temperature automatic calibration system for pressure sensors according to claim 6, characterized in that: The high-mode assembly further includes a vacuum valve (20); The vacuum pump (19) is connected to the outlet of the helium channel (37) through the vacuum valve (20) and the helium outlet in sequence, and is used to evacuate the inside of the helium channel (37).

8. The high-modulus, wide-width, low-temperature automatic calibration system for pressure sensors according to claim 1 or 2, characterized in that: The calibration circuit further comprises a high-pressure gas supply valve (9) and a drive control valve (6); the booster pump (7) is connected to a process drive gas source through the drive control valve (6) to provide process drive gas for the booster pump (7); The replacement path includes a replacement gas source valve (8), a replacement pressure reducer (30), a replacement gas supply valve (27) and a pressure regulating port (17); The gas cylinder group (1) is divided into two paths after passing through the gas source supply valve (3): one path passes through the booster pump (7) and the high-pressure gas supply valve (9) in sequence, and is connected to the inlet end of the gas collecting pipe (13), and supplies high-pressure helium gas used as a calibration medium to the pressure calibration unit; the other path passes through the replacement gas source valve (8), the replacement pressure reducer (30), the replacement gas supply valve (27) and the pressure regulating port (17) in sequence, and is connected to the inner cavity of the temperature control box (32), and supplies helium gas for replacing air into the temperature control box (32).

9. The high-modulus, wide-width, low-temperature automatic calibration system for pressure sensors according to claim 8, characterized in that: An air source filter (5) is provided on the calibration path at a position upstream of the helium supply of the booster pump (7), and the air source supply valve (3) is connected to the booster pump (7) through the air source filter (5); a high-pressure filter (11) is provided on the calibration path at a position downstream of the helium supply of the high-pressure supply valve (9), and the high-pressure supply valve (9) is connected to the inlet end of the gas collecting pipe (13) through the high-pressure filter (11); A replacement filter (26) is provided on the replacement path at a position downstream of the helium supply of the replacement gas supply valve (27), and the replacement gas supply valve (27) is connected to the pressure regulating port (17) through the replacement filter (26); On the main pipeline connecting the gas source supply valve (3) and the inlet ends of the calibration path and the replacement path, a first pressure gauge (2) and a gas source release valve (4) are sequentially provided according to the direction of helium flow; A high-pressure air release valve (10) is provided on the calibration path between the high-pressure air supply valve (9) and the high-pressure filter (11); A second pressure gauge (12) and a safety valve (14) are respectively provided at the inlet and outlet ends of the gas collecting pipe (13); On the replacement path, a fourth pressure gauge (31) and a replacement air release valve (28) are provided between the replacement air source valve (8) and the replacement pressure reducer (30), and a third pressure gauge (29) is provided between the replacement pressure reducer (30) and the replacement air supply valve (27).

10. A high-modulus, wide-width, low-temperature automatic calibration method for a pressure sensor, characterized in that: The following steps are involved: Step 1: constructing a high-module, wide-width, low-temperature automatic calibration system for a pressure sensor according to any one of claims 1 to 9, and making all valves in the system closed, at which time the temperature control box (32) is at room temperature and atmospheric pressure; Step 2: The control system and the data acquisition and processing module in the high-module, wide-width, low-temperature automatic calibration system for the pressure sensor constructed in step 1 are turned on, with all valves in the closed state; then, the power supplies of all valves and instruments and meters in the gas source supply valve (3), the calibration line, the pressure calibration unit, and the connecting line between the pressure calibration unit and the helium channel (37), except for the valve for venting, are turned on; then, the gas cylinder group (1) is turned on, and helium is introduced into the helium channel (37) to discharge the air in the pipeline from the sensor connector (40); Step 3: Installing the pressure sensor to be calibrated on the sensor connector (40); Step 4: According to the calibration requirements, the booster pump (7) is parameterized and the booster pump (7) is started to pressurize the gas collecting pipe (13) through the booster pump (7). When the pressure of the gas collecting pipe (13) reaches the working pressure, the pressure sensor to be calibrated installed in step 3 is tested for air tightness. After the air tightness test is passed, the door of the temperature control box (32) is closed and the booster pump (7) is turned off. Step 5: All valves, instruments, and meters on the replacement path except the valve for deflation, as well as the deflation regulating valve (23), are opened, and helium is delivered to the inner cavity of the temperature control box (32) to replace the air in the temperature control box (32) with helium. After delivering helium for at least 3 minutes, all valves, instruments, and meters on the replacement path, as well as the deflation regulating valve (23), are closed; Step 6: Determine whether the pressure sensor to be calibrated installed in step 3 is an absolute pressure sensor; if so, proceed to step 7; if not, the pressure sensor to be calibrated is a gauge pressure sensor, proceed to step 8; Step 7: Start the vacuum pump (19) and open the valve on the connecting pipeline between the vacuum pump (19) and the outlet end of the helium channel (37) to evacuate the connecting pipeline between the gas cylinder group (1) and the inlet end of the calibration road, the calibration road, the pressure calibration unit and the helium channel (37). When the vacuum degree of the helium channel (37) displayed by the pressure calibrator (15) reaches the vacuum degree required for calibration, close the vacuum pump (19) and the valve on the connecting pipeline between the vacuum pump (19) and the outlet end of the helium channel (37); Step 8: Turn on the liquid nitrogen supply unit to supply liquid nitrogen to the liquid nitrogen coil (33) and the liquid nitrogen channel (38); Step 9: According to the calibration requirements, the calibration parameters of the pressure calibrator (15) are set; then the booster pump (7) and the pressure calibrator (15) are started, and the pressure sensor to be calibrated installed in step 3 is subjected to at least three cycles of loading and unloading calibration tests. During the calibration test, the control system communicates with the pressure calibrator (15), and the pressure parameters of the pressure sensor to be calibrated and the standard pressure sensor (16) and the temperature parameters of each temperature sensor are collected in real time through the data acquisition and processing module. The PID closed-loop control method is used to control the opening, closing and opening size adjustment of each valve in the liquid nitrogen supply unit in real time according to the collected temperature parameters of each temperature sensor, so as to ensure that the temperature of the helium in the helium channel (37) meets the calibration requirements; Step 10: The control system automatically generates original records and a calibration certificate for the pressure sensor to be calibrated based on the calibration requirements and the parameters collected by the data acquisition and processing module during the calibration test in step 9; Step 11: Close the liquid nitrogen supply unit, the helium source module and the pressure calibration unit, open the door of the temperature control box (32), return the temperature of the temperature control box (32), remove the pressure sensor to be calibrated installed in step 3, and seal the sensor connector (40) to facilitate the next calibration, thereby completing the calibration.

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