High-precision platinum resistor calibration device and calibration method

Abstract

The invention belongs to the technical field of high-precision temperature testing, and particularly relates to a high-precision platinum resistor calibration device and calibration method. The device comprises an upper computer, a multi-channel temperature acquisition instrument, a temperature control box, a guide tube, a bracket, an acquisition channel expansion module, platinum resistors, a locking seat, a rotary locking cover, a jointing clamp and the like, the temperature control box provides a stable and uniform temperature field, and the multi-channel temperature acquisition instrument is matched with the expansion module to realize synchronous acquisition of resistance values of the platinum resistors; the guide tube, the locking seat, the rotary locking cover and the support ensure that the platinum resistor is located in a temperature field core area. According to the calibration method, a plurality of known temperature points including 0 DEG C are selected, an equation set is constructed based on collected data, and the coefficient of a sensor characteristic equation is solved so as to achieve accurate calculation of the temperature. The problems that an existing calibration device is complex in operation and cannot give consideration to high precision and high efficiency are solved, the device has the advantages of being compact in structure, easy and convenient to operate, high in calibration precision, capable of achieving batch calibration and the like, the platinum resistor can improve the measurement precision after calibration, and reliable technical support is provided for steady-state temperature measurement of a fan / gas compressor.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-precision temperature testing, and specifically relates to a high-precision platinum resistance calibration device and calibration method, which are suitable for high-precision calibration of platinum resistances used for temperature testing. The designed device and calibration method have a compact structure, simple operation, and high calibration efficiency, thereby improving the measurement accuracy of platinum resistance and providing reliable technical support for steady-state temperature measurement of fans / compressors. Background Art

[0002] In fan / compressor tests, the isentropic efficiency is calculated as:

[0003]

[0004] Among them, η c is the compressor isentropic efficiency, T1 * is the total temperature at the compressor inlet, T2 * is the total temperature at the compressor outlet, π c is the compressor total pressure ratio, and K is the specific heat ratio. Therefore, to determine compressor efficiency, it is necessary to measure the compressor inlet / outlet total temperature and total pressure. Accurately measuring the temperature of the compressor inlet and outlet cross-sections is a key technical support for the development of high-performance aircraft engines. Cross-section temperature can be measured using a high-precision platinum resistance total temperature probe. To ensure measurement accuracy, the platinum total temperature probe typically requires static calibration.

[0005] Existing calibration methods for platinum resistance temperature sensors include the ITS-90 International Temperature Scale (ITS-90) and the CVD equation method. The ITS-90 International Temperature Scale uses a series of internationally defined fixed points (such as the freezing points of metals like aluminum, zinc, and tin) as temperature references. Standard platinum resistance thermometers measure the resistance at each fixed point temperature. Using a reference function and a deviation function, an interpolation algorithm is then used to calculate the temperature-resistance relationship between the fixed points. This method offers high calibration accuracy and meets stringent scientific research and metrology requirements. However, its disadvantages include the need for multiple high-purity metal fixed-point devices, resulting in high equipment costs. The calibration process is complex, requiring repeated heating, insulation, and cooling, which is time-consuming and requires stringent operating conditions. Furthermore, the calibration process is highly sensitive to environmental conditions such as laboratory temperature and the fluid medium, making it difficult to scale up. The CVD (Callendar–Van Dusen) equation method uses a predefined empirical formula to describe the relationship between the resistance and temperature of a platinum resistance sensor as a polynomial or high-order function. International standards such as IEC-60754 provide typical equation coefficients, simplifying the calibration process. Users only need to measure room temperature and a few temperature points to complete calibration. However, due to factors such as the platinum wire manufacturing process, tolerance errors, and assembly method, the equation coefficients can vary between batches or even between the same sensor under different environmental conditions. This makes it difficult to achieve the required temperature measurement accuracy (0.2K) required by high-performance fans and compressors in the low temperature rise environment.

[0006] Given the advantages and disadvantages of both methods, neither of which offers the same high precision and efficiency, there is an urgent need for a platinum resistance thermocouple static calibration device and method that combines rapidity, accuracy, and reliability. This high-precision static calibration of platinum resistance thermocouples would provide reliable measurement methods and technical support for enhancing understanding of fan / compressor inlet / outlet flow fields and enabling high-performance fan / compressor design. Summary of the Invention

[0007] The present invention is a high-precision platinum resistor calibration device and calibration method, comprising a host computer, a multi-channel temperature collector, a temperature control box, a guide tube, a bracket, a collection channel expansion module, a platinum resistor, a locking seat, a rotary locking cover, a height adjustment knob, and a wiring clamp. The temperature control box can provide a stable spatially uniform temperature field for platinum resistor calibration according to the set temperature point. The multi-channel temperature collector realizes the collection of the resistance value of the platinum resistor, and when used with the collection channel expansion module, it can collect the resistance values ​​of different numbers of platinum resistors. The combined use of the guide tube, the locking seat, the rotary locking cover and the bracket ensures that the platinum resistor can be extended into the proper position of the constant temperature hole to avoid the platinum resistor hitting the wall and affecting the calibration accuracy. The host computer is connected to the multi-channel temperature collector to realize data transmission, storage and processing.

[0008] The present invention provides a high-precision platinum resistor calibration device and method. The technical problems to be solved are: first, the difficulty in operation and complex procedures of existing platinum resistor calibration devices need to be addressed. Second, the limited number of single calibrations and low calibration efficiency of existing platinum resistors need to be addressed. Third, the local errors caused by the single coefficient fitting across the entire range of existing platinum resistor calibration methods need to be addressed. Fourth, the calibration accuracy of existing platinum resistors needs to be improved.

[0009] The technical solution of the present invention is:

[0010] 1. A high-precision platinum resistance calibration device, comprising a host computer (1), a multi-channel temperature collector (2), a temperature control box (3), a constant temperature hole (4), a guide tube (5), a bracket (6), a collection channel expansion module (7), a platinum resistor (8), a locking seat (9), a rotary locking cover (10), a height adjustment knob (11), and a wiring clamp (12), characterized in that: the platinum resistor (8) extends into the constant temperature hole (4) of the temperature control box (3) through the guide tube (5), the guide tube (5) is fixed to the locking seat (9) by rotating the locking cover (10), the locking seat (9) and the bracket (6) are connected by bolts, the lead of the platinum resistor (8) is led out through the tail of the guide tube (5) and connected to the wiring clamp (12) of the collection channel expansion module (7), the input end of the multi-channel temperature collector (2) is connected to the output end of the collection channel expansion module (7), and the host computer (1) is connected to the output end of the multi-channel temperature collector (2);

[0011] 2. The temperature control box (3) is a cubic structure. The temperature control box (3) is 300-400 mm long, 300-400 mm wide, and 150-200 mm high. It has a control panel and a display screen. The control panel is operated according to the required calibration temperature to adjust the temperature of the constant temperature hole (4). The cross section of the constant temperature hole (4) is circular, and its axial, radial and circumferential temperature fields are uniform. The temperature control box (3) has multiple constant temperature holes (4), which can realize the simultaneous calibration of multiple platinum resistors (8). The arrangement of the constant temperature holes (4) is linear, and can also be selected as arc or rectangular. The diameter of the constant temperature hole (4) is 5-25 mm and the depth is 100-300 mm, which meets the calibration requirements of platinum resistors (8) of different sizes;

[0012] 3. The guide tube (5) is a hollow cylinder with a truncated cone-shaped head. A cylindrical type can also be selected. The outer diameter of the guide tube (5) is 2 to 20 mm, and the inner diameter of the guide tube (5) is 1 to 19 mm. The lead of the platinum resistor (8) is introduced from the head of the guide tube (5) and led out from the tail. The distance between the platinum resistor (8) and the upper surface of the head of the guide tube (5) is 1 to 2 mm and an insulating material is filled in this area. The head of the platinum resistor (8) is fixed. The material of the guide tube (5) meets the temperature requirements during the calibration process.

[0013] 4. The bracket (6) and the locking seat (9) are connected by bolts. The guide tube (5) extends into the center hole of the locking seat (9). The guide tube (5) is locked by rotating the locking cover (10). The diameter of the center hole of the locking seat (9) is 2 to 20 mm. The bracket (6) is an X-shaped telescopic structure. By rotating the height adjustment knob (11), the height range of the bracket (6) is adjusted to 50 to 200 mm.

[0014] 5. The multi-channel temperature collector (2) is a cubic structure. The multi-channel temperature collector (2) is 150 to 300 mm long, 200 to 300 mm wide, and 100 to 150 mm high. It is used for collecting the resistance value of the platinum resistor (8). The front panel of the multi-channel temperature collector (2) has a display window, operation buttons, and an input port. The input port can complete the collection of the resistance values ​​of different numbers of platinum resistors (8) through different wiring methods. In the single collection mode, the input end of the front panel of the multi-channel temperature collector (2) is connected to the lead wire of the platinum resistor (8) to collect the resistance value. In the extended collection mode, the input end of the front panel of the multi-channel temperature collector (2) is connected to the output end of the collection channel expansion module (7) using an RS485 aviation plug for wired connection. The input end wiring clip (12) of the collection channel expansion module (7) is connected to the lead wire of the platinum resistor (8);

[0015] 6. The acquisition channel expansion module (7) is a cubic structure. The acquisition channel expansion module (7) is 80 to 120 mm long, 50 to 80 mm wide, and 20 to 40 mm high. The number of input ports is 2 to 12. The input port lead head has four wiring clips (12) for connecting the platinum resistance (8) lead.

[0016] 7. The host computer (1) is connected to the multi-channel temperature collector (2) for data transmission, storage and processing. The host computer (1) and the multi-channel temperature collector (2) can be connected via a USB wired connection or a wireless network;

[0017] 8. The present invention proposes a high-precision platinum resistance temperature sensor calibration method based on a high-precision platinum resistance temperature sensor calibration device. After completing the installation preparation according to the above requirements, the temperature calibration module (1), the multi-channel temperature acquisition module (2), and the host computer PC module (3) are turned on, and the multi-hole temperature control box (3) is adjusted to make the temperature of the constant temperature hole (9) reach the calibration point temperature value. When the resistance value of the platinum resistor (8) reaches a dynamic equilibrium, the resistance value of the platinum resistor (8) is recorded, and according to the actual temperature measurement range of the platinum resistor (8), multiple calibration temperature points including 0°C are selected, and the resistance value of the platinum resistor (8) at each calibration temperature point is recorded. Using the resistance values ​​of 0°C and the other two calibration temperature points, combined with the temperature characteristics of the platinum resistor (8) from 0 to 650°C, the equation group can be obtained:

[0018]

[0019] in

[0020] t1 is the temperature value of temperature point 1, in °C;

[0021] t2 is the temperature value of temperature point 2, in °C;

[0022] R0 is the resistance value at 0℃, in Ω;

[0023] R t1 is the resistance value at temperature point t1, in Ω;

[0024] R t2 is the resistance value at temperature t2, in Ω;

[0025] A and B are coefficients related to the temperature characteristics of the platinum resistance temperature sensor.

[0026] The simultaneous solution can be obtained:

[0027]

[0028] 9. Substituting the resistance values ​​of all calibration temperature points into the above formula in turn, we can get a series of constants A and B. In the actual temperature measurement process, select the constants A and B obtained from the two sets of calibration temperature points that include the measured temperature and are closest to the measured temperature, and combine them with the formula:

[0029]

[0030] Calculate the measured temperature value.

[0031] The present invention provides a high-precision platinum resistance calibration device and calibration method, which has the following beneficial effects:

[0032] Beneficial effect 1: The high-precision platinum resistance calibration device designed by the present invention has a compact structure, simple operation, and is convenient for operators to use.

[0033] Beneficial effect 2: The platinum resistor calibration device designed by the present invention can calibrate multiple platinum resistors at one time, thereby improving the efficiency of platinum resistor calibration and being suitable for calibration of large quantities of platinum resistors.

[0034] Beneficial effect three: The platinum resistance calibration method designed in the present invention avoids the full-scale fixed coefficient error, and improves the measurement accuracy of each temperature range through segmented calibration and dynamic coefficient matching.

[0035] Beneficial effect four: The high-precision platinum resistor calibration device and calibration method designed in the present invention improve the calibration accuracy of the platinum resistor and the accuracy of temperature measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Schematic diagram of a high-precision platinum resistance calibration device with an expansion module in an embodiment of the present invention.

[0037] Figure 2 Schematic diagram of a high-precision platinum resistance calibration device in an embodiment of the present invention.

[0038] Figure 3 This is a schematic diagram of the installation of the platinum resistance in the guide tube.

[0039] Figure 4 yes Figure 3 A partial enlarged view of .

[0040] Figure 5 It is a structural diagram of the bracket.

[0041] Figure 6 Schematic diagram of the rotary locking cover.

[0042] Figure 7 Schematic diagram of the locking seat

[0043] Figure 8The platinum resistance calibration results of the embodiment of the present invention in the temperature range of 0 to 100 ° C are as follows:

[0044] Among them: 1- host computer, 2- multi-channel temperature collector, 3- temperature control box, 4- constant temperature hole, 5- guide tube, 6- bracket, 7- acquisition channel expansion module, 8- platinum resistor, 9- locking seat, 10- rotary locking cover, 11- height adjustment knob, 12- wiring clamp. DETAILED DESCRIPTION

[0045] The present invention is described in detail below with reference to the accompanying drawings and specific implementation examples, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more precise definition of the protection scope of the present invention.

[0046] like Figures 1 to 7 The present invention shows a high-precision platinum resistance calibration device comprising a host computer (1), a multi-channel temperature acquisition instrument (2), a temperature control box (3), a guide tube (5), a bracket (6), an acquisition channel expansion module (7), a platinum resistance (8), a locking seat (9), a rotary locking cover (10), a height adjustment knob (11), and a wiring clamp (12).

[0047] The temperature control box (3) is a cubic structure with a length of 300 mm, a width of 350 mm, and a height of 150 mm. It has a control panel and a display screen. The temperature control box (3) has four constant temperature holes (4) that can realize the simultaneous calibration of four platinum resistors (8). The constant temperature holes (4) have a diameter of 12 mm and a depth of 200 mm. The cross section of the constant temperature holes (4) is circular, and the axial, radial and circumferential temperature fields are uniform.

[0048] The guide tube (5) is a hollow cylinder with a truncated cone-shaped head. The outer diameter of the guide tube (5) is 8 mm, the inner diameter of the guide tube (5) is 7 mm, and the guide tube (5) is a ceramic corundum tube.

[0049] The bracket (6) and the locking seat (9) are connected by bolts. The diameter of the center hole of the locking seat (9) is 8 mm. The threads of the locking seat (9) and the rotating locking cover (10) are M16 coarse threads. The bracket (6) is an X-shaped telescopic structure. By rotating the height adjustment knob (11), the height range of the bracket (6) can be adjusted to 50 to 100 mm.

[0050] The multi-channel temperature collector (2) is a cubic structure with a length of 200 mm, a width of 300 mm and a height of 120 mm. Its front panel has a display window, operation buttons and input ports, and the number of input ports is 12.

[0051] The acquisition channel expansion module (7) is a cubic structure. The acquisition channel expansion module (7) is 100 mm long, 50 mm wide, and 30 mm high. The number of input ports is 9, and the input port lead head has 4 wiring clips (12).

[0052] First, the lead wire of the platinum resistor (8) is inserted into the head of the guide tube (5) and led out from the tail. The distance between the platinum resistor (8) and the upper surface of the head of the guide tube (5) is 1 mm, and the area is filled with insulating heat-insulating material. The guide tube (5) is installed on the locking seat (9) of the bracket (6), and is locked by rotating the locking cover (10). The height adjustment knob (11) is rotated to adjust the height of the bracket (6). The guide tube (5) is inserted into the constant temperature hole (4) to a distance of 150 mm, and the guide tube (5) and the constant temperature hole (4) are coaxial to avoid contact between the platinum resistor (8) and the wall of the constant temperature hole (4). Then, the lead wire of the platinum resistor (8) is connected to the input terminal wiring clamp (12) of the acquisition channel expansion module (7), the output terminal of the acquisition channel expansion module (7) is connected to the input terminal of the multi-channel temperature acquisition instrument (2), and the host computer (1) and the multi-channel temperature acquisition instrument (2) are connected using a USB wired connection.

[0053] After completing the above installation preparation, the host computer (1), the multi-channel temperature collector (2), and the temperature control box (3) are turned on, and the working mode of the multi-channel temperature collector (2) is set to the extended mode and the four-wire platinum resistor (8) acquisition mode. In this embodiment, the calibration temperature range is 0-100°C, and the calibration temperature point selection includes 0°C. The calibration is performed every 10°C. The temperature of the temperature control box (3) is adjusted to the calibration point temperature value until the resistance value of the platinum resistor (8) reaches a dynamic balance. The resistance value collected by the multi-channel temperature collector (2) fluctuates within ±0.002Ω. The resistance value of the calibration point is collected until the resistance value collection of all calibration temperature points is completed. Using the resistance values ​​of 0°C and the other two calibration temperature points, combined with the temperature characteristics of the 0-100°C platinum resistor (8), the equation group can be obtained:

[0054]

[0055] The simultaneous solution can be obtained:

[0056]

[0057] Therefore, by substituting the resistance values ​​of all calibration temperature points into the above formula in turn, a series of constants A and B can be obtained. In the actual temperature measurement process, the constants A and B obtained from the two sets of calibration temperature points that include the measured temperature and are closest to the measured temperature are selected and combined with the formula:

[0058]

[0059] Calculate the measured temperature value.

[0060] In this embodiment, the four-wire Pt100 platinum resistor is calibrated, and the static temperature measurement deviation at each temperature point is as follows: Figure 8As shown in the figure, the calibration results achieved 1 / 10B grade accuracy, with a static deviation range of less than 0.08°C from 0 to 100°C, which is better than grade A and AA accuracy. This improves the measurement accuracy of the platinum resistance and significantly reduces the static deviation of the platinum resistance.

Claims

1. A high-precision platinum resistance calibration device, comprising a host computer (1), a multi-channel temperature acquisition instrument (2), a temperature control box (3), a constant temperature hole (4), a guide tube (5), a bracket (6), an acquisition channel expansion module (7), a platinum resistance (8), a locking seat (9), a rotary locking cover (10), a height adjustment knob (11), and a wiring clamp (12), characterized in that: The platinum resistor (8) extends into the constant temperature hole (4) of the temperature control box (3) through the guide tube (5), the guide tube (5) is fixed to the locking seat (9) by rotating the locking cover (10), the locking seat (9) and the bracket (6) are connected by bolts, the lead of the platinum resistor (8) is led out through the tail of the guide tube (5) and connected to the wiring clamp (12) of the acquisition channel expansion module (7), the input end of the multi-channel temperature acquisition instrument (2) is connected to the output end of the acquisition channel expansion module (7), and the host computer (1) is connected to the output end of the multi-channel temperature acquisition instrument (2); The temperature control box (3) is a cubic structure. The temperature control box (3) is 300-400 mm long, 300-400 mm wide, and 150-200 mm high. It has a control panel and a display screen. The control panel is operated according to the required calibration temperature to adjust the temperature of the constant temperature hole (4). The cross section of the constant temperature hole (4) is circular, and the axial, radial and circumferential temperature fields inside it are uniform. The temperature control box (3) has multiple constant temperature holes (4), which can realize the simultaneous calibration of multiple platinum resistors (8). The arrangement of the constant temperature holes (4) is linear, and can also be selected as arc or rectangular. The diameter of the constant temperature hole (4) is 5-25 mm, and the depth is 100-300 mm, which meets the calibration requirements of platinum resistors (8) of different sizes. The guide tube (5) is a hollow cylinder, and the head is a truncated cone type, and a cylindrical type can also be selected. The outer diameter of the guide tube (5) is 2 to 20 mm, and the inner diameter of the guide tube (5) is 1 to 19 mm. The lead of the platinum resistor (8) is introduced from the head of the guide tube (5) and led out from the tail. The distance between the platinum resistor (8) and the upper surface of the head of the guide tube (5) is 1 to 2 mm and an insulating material is filled in the area. The head of the platinum resistor (8) is fixed, and the material of the guide tube (5) meets the temperature requirements during the calibration process. The bracket (6) and the locking seat (9) are connected by bolts. The guide tube (5) extends into the center hole of the locking seat (9). The guide tube (5) is locked by rotating the locking cover (10). The diameter of the center hole of the locking seat (9) is 2 to 20 mm. The bracket (6) is an X-shaped telescopic structure. By rotating the height adjustment knob (11), the height range of the bracket (6) is adjusted to 50 to 200 mm. The multi-channel temperature collector (2) is a cubic structure. The multi-channel temperature collector (2) is 150 to 300 mm long, 200 to 300 mm wide, and 100 to 150 mm high. It is used for collecting resistance values ​​of a platinum resistor (8). The front panel of the multi-channel temperature collector (2) has a display window, operation buttons, and an input port. The input port of the multi-channel temperature collector (2) and the output port of the acquisition channel expansion module (7) are connected by wire using an RS485 aviation plug. In a single acquisition mode, the input end of the front panel of the multi-channel temperature collector (2) is connected to the lead of the platinum resistor (8) to collect resistance values. In an extended acquisition mode, the input end of the front panel of the multi-channel temperature collector (2) is connected to the output end of the acquisition channel expansion module (7), and the input end wiring clip (12) of the acquisition channel expansion module (7) is connected to the lead of the platinum resistor (8). The acquisition channel expansion module (7) is a cubic structure, and is 80 to 120 mm long, 50 to 80 mm wide, and 20 to 40 mm high. The number of input ports is 2 to 12, and the input port lead head has four wiring clips (12) for connecting the platinum resistor (8) lead. The host computer (1) is connected to the multi-channel temperature collector (2) for data transmission, storage and processing. A USB wired connection or a wireless network connection can be selected between the host computer (1) and the multi-channel temperature collector (2).

2. A high-precision platinum resistor calibration device according to claim 1 proposes a high-precision platinum resistor calibration method. After completing the installation preparation according to the above requirements, the host computer (1), the multi-channel temperature collector (2), and the temperature control box (3) are turned on, the multi-channel temperature collector (2) is set to a working mode, the temperature control box (3) is adjusted to make the temperature of the constant temperature hole (4) to the calibration point temperature, when the resistance value of the platinum resistor (8) reaches a dynamic equilibrium, the resistance value of the platinum resistor (8) is collected, according to the actual temperature measurement range of the platinum resistor (8), multiple calibration temperature points including 0°C are selected, and the resistance value of the platinum resistor (8) at each calibration temperature point is recorded. Using the resistance values ​​of 0°C and the other two calibration temperature points, combined with the temperature characteristics of the platinum resistor (8) from 0 to 650°C, the equation group can be obtained: in t1 is the temperature value of temperature point 1, in °C; t2 is the temperature value of temperature point 2, in °C; R0 is the resistance value at 0℃, in Ω; R t1 is the resistance value at temperature point t1, in Ω; R t2 is the resistance value at temperature t2, in Ω; A and B are coefficients related to the temperature characteristics of the platinum resistance temperature sensor. The simultaneous solution can be obtained: Therefore, by substituting the resistance values ​​of all calibration temperature points into the above formula in sequence, a series of constants A and B can be obtained. In actual measurement, the constants A and B obtained from the two sets of calibration temperature points that include the measured temperature and are closest to the measured temperature are selected and combined with the formula: Calculate the measured temperature value; This invention solves the problem that existing calibration devices are complex to operate and cannot achieve both high precision and high efficiency. It has the advantages of compact structure, simple operation, high calibration accuracy, and batch calibration. After calibration, the measurement accuracy of the platinum resistance is improved, providing reliable technical support for the steady-state temperature measurement of fans / compressors.

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