Testing device for industrial thermal resistance temperature sensing element

Abstract

The invention relates to a testing device for an industrial thermal resistance temperature-sensing element, which comprises at least two connecting plates, each connecting plate is provided with an insulating substrate, each insulating substrate is internally provided with a via hole, the surface of each insulating substrate is provided with a conductor layer, the conductor layers are arranged on the left and right sides of the upper and lower sides of the temperature-sensing element connecting plate, and the conductor layers are arranged on the left and right sides of the temperature-sensing element connecting plate. A conductor layer on the change-over switch connecting plate is connected with the change-over switch through a test lead and is used for transmitting resistance data obtained by testing to an electrical testing instrument, and the surface, connected with the test lead, of the conductor layer of the change-over switch connecting plate is oppositely attached to the surface, connected with the element to be tested, of the temperature sensing element connecting plate through a fastener. According to the testing device, the pollution risk caused by traditional brazing can be thoroughly avoided, and a solid foundation is laid for follow-up precision manufacturing of thermal resistance elements while the testing precision is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of temperature sensor testing technology, and more specifically to a testing device for industrial resistance temperature sensors. Background Technology

[0002] Resistance temperature detectors (RTDs), temperature sensors designed based on the temperature-dependent resistance of metals, hold an irreplaceable position in many fields with stringent temperature parameter requirements, such as industrial process control, energy, chemical engineering, and aerospace, thanks to their superior temperature measurement accuracy and stability. The temperature-sensing element, as the core component of the RTD, directly determines the measurement quality of the entire sensor. It achieves high-precision, long-term stable temperature monitoring by selecting precision alloy materials (such as platinum, copper, and nickel) and combining them with specific structural designs. Therefore, accurately measuring the resistance value of the temperature-sensing element before packaging is a crucial step in ensuring that the RTD product meets performance standards and application requirements.

[0003] Currently, in the process of detecting the resistance value of temperature sensing elements, the first step is to solder the temperature sensing element leads to the test cable (i.e., the test lead) using a brazing process. Specifically, this involves heating and melting solder, then solidifying the solder at the connection point between the lead and the test cable to form a solder joint, thus establishing circuit continuity and completing the resistance measurement. Next, the temperature sensing element leads are separated from the test cable, and then the temperature sensing element leads are connected to the armor leads using an oxyhydrogen welding process, thereby forming a complete thermometer product.

[0004] However, a significant and difficult-to-detect technical problem exists in this process: To ensure welding quality, brazing processes typically use alloy solders such as tin-lead alloys and lead-free solders, along with flux. During the brazing process of connecting the temperature sensing element leads to the test cable, these alloy solders and fluxes often remain at the solder joint and in areas close to it (hereinafter referred to as the soldering end).

[0005] Even after disconnecting the temperature sensing element leads from the test cables, some residue will still remain at the solder joints of the leads. This is because these residues have extremely strong chemical adsorption and physical adhesion properties, making them difficult to completely remove even with conventional cleaning methods such as ultrasonic cleaning and organic solvent wiping.

[0006] However, in the subsequent packaging process, the leads of the armor body need to be connected using an oxyhydrogen welding process to form a complete thermometer product. During this process, residues at the lead welding ends can form thin films or particulate impurities that are difficult to detect with the naked eye at the solder joints under high temperatures, leading to the deterioration of the solder joint's microstructure.

[0007] More seriously, as the product is used for a longer period of time, this microstructure deterioration will gradually intensify, which will directly manifest as a gradual increase in the contact resistance of the solder joints, eventually leading to complete failure of the solder joints, an open circuit, and the thermometer completely losing its temperature measurement function.

[0008] During long-term use, it has been found that the performance degradation of this type of resistance temperature sensing element is extremely insidious and gradual, and is often difficult to detect during product inspection before leaving the factory. In harsh application scenarios such as aerospace and nuclear industry, once the temperature measurement data is distorted or interrupted due to solder joint failure, it may cause equipment failure, production accidents, or even endanger personal safety, constituting a significant systemic quality risk. Summary of the Invention

[0009] The purpose of this invention is to address the shortcomings of existing technologies by providing a testing device for industrial resistance temperature detectors (RTD) elements. This fixture completely avoids the contamination risks introduced by traditional brazing, ensuring testing accuracy while maintaining a clean metallic state on the surface of the temperature sensor lead wires (i.e., preventing the formation of thin films or particulate impurities that are difficult to detect with the naked eye). This lays the technological foundation for subsequent high-reliability hydrogen-oxygen welding, thereby meeting the stringent performance requirements of temperature sensors in cutting-edge fields.

[0010] The objective of this invention is achieved through the following approach: A testing device for an industrial resistance temperature detector (RTD) element includes at least two connecting plates. Each connecting plate has an insulating substrate with through holes and a conductor layer on its surface. The RTD connecting plate has conductor layers on its top, bottom, left, and right sides. The conductor layer on the switch connecting plate is connected to a switch via test leads to transmit the measured resistance data to an electrical measuring instrument. The side of the switch connecting plate with the test leads and the side of the RTD connecting plate with the element under test are fastened together.

[0011] Preferably, the conductor layer is made of copper or silver.

[0012] Preferably, the insulating substrate of the temperature sensing element connecting plate is provided with conductor layers on both the upper and lower sides, and the insulating substrate of the changeover switch connecting plate is provided with a conductor layer on one side. The conductor layer includes a first conductor layer and a second conductor layer, and the first conductor layer and the second conductor layer are respectively located on the left and right sides of the connecting plate. The conductor layers on both sides of the temperature sensing element connecting plate are in contact with the conductor layer of the changeover switch connecting plate.

[0013] Preferably, two test wires are welded to the first conductor layer and the second conductor layer of the switch connection plate, respectively.

[0014] Preferably, the connecting plate is arranged in the form of a long strip.

[0015] Preferably, the method for measuring the resistance value of a temperature-sensing element using a testing device includes the following steps: 1) Crim one end of the two leads of the component under test onto the connection plate of the test device and connect it to the test lead; 2) Measure the resistance value of the temperature sensing element.

[0016] The beneficial effects of this invention are as follows: (1) The testing device of the present invention uses at least two connecting plates and sets conductor layers at corresponding positions on the insulating substrate surface of the connecting plates. By welding the test wires to one side of the conductor layer of the two opposing connecting plates (i.e., the changeover switch connecting plates), and using fasteners to stably clamp the pins of the component under test (i.e., the temperature sensing element under test) between the connecting plates, and forming corresponding positive and negative poles in the testing process through the corresponding contacting conductor layers, the connection method between the temperature resistance element and the testing system is transformed from traditional welding to high-reliability crimping. This completely eliminates the contamination introduced by solder alloy and flux residues during the brazing process, fundamentally solving the long-standing problem of lead wire contamination during temperature resistance element testing, ensuring the clean metallic state of the temperature resistance element lead surface, laying a process foundation for the high reliability of subsequent hydrogen-oxygen welding, and thus providing a solid guarantee for the precision manufacturing of temperature resistance elements. It also provides key technical support for the research and development and large-scale production of high-performance temperature resistance elements.

[0017] (2) The testing device of the present invention provides a changeover switch connecting plate on both sides of the temperature sensing element connecting plate, and makes the conductor layer on both sides of the temperature sensing element connecting plate face to face with the conductor layer of the changeover switch connecting plate. This structure effectively forms a dual-channel testing channel, thereby having the ability to test two temperature sensing elements in parallel with a single fixture. It can test two temperature sensing elements simultaneously and efficiently, significantly improving the number of tests per unit time and the overall testing efficiency, and can meet the testing needs of large-scale production.

[0018] (3) By setting multiple through holes on the insulating substrate of the connecting plate and fixing them with fasteners such as bolts, screws and nuts, the present invention can precisely control the clamping force between the two connecting plates. This ensures good electrical contact between the pins of the component under test and the conductor layer, ensuring the stability and accuracy of the resistance signal transmission, while avoiding the risk of pin damage due to excessive clamping force. This achieves non-destructive fixing of the component under test and further ensures the reliability and integrity of the component under test during the testing process.

[0019] (4) This invention achieves the conversion from two-wire thermal resistance element to four-wire measurement by designing the conductor layer on the surface of the connecting plate as a first conductor layer and a second conductor layer structure that are separated by an insulating substrate, and by using a multi-core copper wire configuration, effectively eliminating the interference of lead resistance on the measurement results. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the connecting plate in this invention; Figure 2 This is a schematic diagram of the testing device of the present invention in use; Figure 3 This is a schematic diagram of cyclic readings in an embodiment of the present invention; Figure 4 This is an exploded view of each connecting plate of the testing device of the present invention; Figure 5 This is a schematic diagram of the mating surfaces of the connecting plates in this invention. Detailed Implementation

[0021] like Figures 1 to 5 As shown, a testing device for an industrial resistance temperature detector (RTD) element includes at least two connecting plates. Each connecting plate is provided with an insulating substrate 2, which has a through hole 7. A conductor layer is provided on the surface of the insulating substrate 2. Conductor layers are provided on the upper, lower, left, and right sides of the temperature detector connecting plate 5. The conductor layer on the switch connecting plate 6 is connected to the switch via a test wire 1 to transmit the resistance data obtained from the test to an electrical measuring instrument. The side of the switch connecting plate 6 where the test wire 1 is connected and the side of the temperature detector connecting plate 5 where the element under test 8 is connected are fitted together by fasteners.

[0022] like Figure 1 As shown, the insulating substrate 2 of the temperature sensing element connecting plate 5 has conductor layers on both its upper and lower sides, and the insulating substrate 2 of the changeover switch connecting plate 6 has a conductor layer on only one side. The conductor layers are made of copper, silver, or other materials with good conductivity. In this embodiment, the conductor layer is copper. The conductor layer includes a first conductor layer 3 and a second conductor layer 4, which are spaced apart by the insulating substrate 2 and located on the left and right sides of the connecting plate, respectively, to ensure electrical disconnection and facilitate four-wire measurement, eliminating interference from lead resistance on the measurement results. In this embodiment, the insulating substrate 2 is made of glass fiber.

[0023] Test lead 1 is soldered to the corresponding conductor layer to form a stable electrical connection, ensuring accurate transmission of the resistance signal. Furthermore, two test leads 1 are soldered to the first conductor layer 3 and the second conductor layer 4 of the changeover switch connection plate 6, respectively. This ensures that the two test leads on each conductor layer correspond to the current loop and the voltage measurement loop, thus meeting the circuit configuration requirements for four-wire measurement and effectively avoiding the influence of the lead's own resistance on measurement accuracy. Moreover, the test lead 1 is a multi-core copper wire. This design is chosen because multi-core copper wires possess excellent conductivity and mechanical flexibility, reducing signal transmission loss.

[0024] The conductor layers on both sides of the temperature sensing element connecting plate 5 are in contact with the conductor layer of the changeover switch connecting plate 6. Specifically, at least two through holes 7 are formed along the length of the connecting plate in the insulating substrate 2 of the temperature sensing element connecting plate 5 and the changeover switch connecting plate 6 for fasteners to pass through. In this embodiment, two through holes 7 are provided. Fasteners (such as bolts, screws and nuts) are used to make the two adjacent connecting plates fit together, thereby forming a clamping and positioning of the element to be tested 8 (such as a film resistor element, a wire-wound resistor element, etc.).

[0025] It should be noted that the thickness of the insulating substrate in the middle of the connecting board is greater than that on both sides. Therefore, when manufacturing the laminate, it is usually necessary to first drill holes in the insulating substrate to obtain vias 7, and then process the conductor layer (i.e., copper-clad surface) on the surface of the connecting board by grinding or etching until the insulating substrate in the middle is exposed, and the conductor layer on the same side surface of the connecting board forms a first conductor layer 3 and a second conductor layer 4 that are spaced apart.

[0026] The following is a specific embodiment using the above-mentioned fixture: A method for measuring the resistance value of a temperature-sensing element using a testing device includes the following steps: 1) Crim one end of the two leads of the component under test 8 onto the connection plate of the test device and connect them to the test leads. like Figure 2 As shown, the temperature sensing element connecting plate 5 and the changeover switch connecting plate 6 of the test device are pre-tightened using bolts and fasteners. At this time, there is a gap between the temperature sensing element connecting plate 5 and the changeover switch connecting plate 6. The two pins of the component to be tested 8 are simultaneously placed into the gap between the temperature sensing element connecting plate 5 and the changeover switch connecting plate 6 in the test device, ensuring that the two pins are respectively placed on the first conductor layer 3 and the second conductor layer 4 of the connecting plate. Then, the screws are tightened to make the temperature sensing element connecting plate 5 and the changeover switch connecting plate 6 tightly press the pins, thereby fixing the component to be tested 8.

[0027] 2) Measure the resistance value of the temperature sensing element.

[0028] During the test, the other end of the test lead 1 on the changeover switch connection plate 6 in the test device is connected to the changeover switch and then connected to the electrical testing instrument through the changeover switch. This allows the resistance signal to be transmitted to the electrical testing instrument through the test lead 1 and the changeover switch, and finally the resistance value of the component under test 8 is displayed on the electrical testing instrument.

[0029] In this embodiment, the element under test 8 is an industrial platinum resistance thermometer, and a second-class standard platinum resistance thermometer is used as a standard during the test. Example 1

[0030] The test environment was a 0°C temperature field, provided by a compacted ice-water mixture. The freezing point test was conducted in an ice bottle. To perform the freezing point test using an ice bottle, the ice was first crushed into snowflake-like particles using an ice crusher, then placed into the ice bottle. An appropriate amount of purified water was then added and stirred until it reached a dark color (i.e., forming an ice-water mixture), and then compacted to remove any air bubbles.

[0031] Insert a test tube with a diameter slightly larger than the connecting plate into the ice bottle. Then, insert a Class II standard resistance thermometer into the test tube. Place the temperature sensing element of the thermal resistor being tested into the test tube surrounding the standard platinum resistance thermometer, ensuring that both are inserted to the same depth and to a sufficient depth. Next, connect test lead 1 to the selector switch, and finally connect it to the electrical measuring instrument through the selector switch. After stabilization, proceed as follows... Figure 3 The sequence of readings is shown. Two cycles are completed, for a total of four readings, and the results are recorded. Example 2

[0032] The test environment is a 100℃ temperature field, provided by a constant-temperature oil bath. After connecting the power to the constant-temperature bath and setting the temperature control instrument to 100℃, heating begins. A second-class standard platinum resistance thermometer is then inserted into the center of the constant-temperature oil bath. The temperature-sensing element of the resistance thermometer being tested is inserted around the standard platinum resistance thermometer, ensuring that both are inserted to approximately the same depth and with sufficient depth. After the temperature stabilizes, readings are taken using the same method as when testing at 0℃.

[0033] Based on the test results of Examples 1 and 2 above, the data records in Table 1 below are as follows: Table 1 Data Records of Fixture Testing

[0034] Comparative Example 1 The two pins of the element under test 8 (i.e. the temperature sensing element of the thermal resistance under test) are directly soldered to the test wires and placed in a test tube, so that the test tube is in the same 0°C temperature field test environment as in Example 1, and the other conditions are kept the same as in Example 1.

[0035] Comparative Example 2 The two pins of the component under test 8 are directly soldered to the test leads, and then the component is placed in a test tube, so that the test tube is in the same 100°C temperature field test environment as in Example 2, and the other conditions are the same as in Example 2.

[0036] Based on the test results of Comparative Examples 1 and 2 above, the data records in Table 2 below are as follows: Table 2 Data Records Using Welding Inspection

[0037] The data in Tables 1 and 2 above are processed to obtain Table 3 below: Table 3 Data Processing Results

[0038] Analysis of Table 3 shows that there is no significant difference between the results of the two detection methods, with a maximum error of 0.005℃, which is much smaller than the Class A tolerance of industrial platinum resistance thermometers (0℃ Class A tolerance: ±0.15℃; 100℃ Class A tolerance: ±0.35℃).

[0039] In summary, the connecting plate of this invention, through its conductor layer design separated by an insulating substrate and the configuration of multi-core copper wires, ensures high-precision resistance measurement within the temperature range of 0–100°C. Furthermore, the deviation of the measurement results from those obtained using traditional brazing methods is controlled within 0.005°C, fully meeting the Class A tolerance requirements for industrial resistance thermometers. Simultaneously, the symmetrical connecting plate structure provides dual-channel parallel testing capability, allowing simultaneous clamping of two test components 8, significantly improving testing efficiency.

[0040] Furthermore, this invention achieves non-destructive bonding between the resistance temperature detector (RTD) element and the testing system through a sandwich-type laminated structure and a four-wire electrical connection design. This connection method ensures the integrity and high cleanliness of the sensing element leads, completely avoiding the lead contamination problem introduced by traditional brazing processes. This eliminates the risk of solder joint failure caused by impurities during subsequent hydrogen-oxygen welding, significantly improving the quality stability and long-term reliability of the RTD product.

[0041] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications made to the present invention by those skilled in the art without departing from the spirit of the present invention shall fall within the protection scope of the present invention.

Claims

1. A testing device for an industrial resistance temperature sensor element, characterized in that, It includes at least two connecting plates, each of which is provided with an insulating substrate (2). The insulating substrate (2) is provided with a through hole (7), and a conductor layer is provided on the surface of the insulating substrate (2). The temperature sensing element connecting plate (5) is provided with conductor layers on the upper, lower, left and right sides. The conductor layer on the changeover switch connecting plate (6) is connected to the changeover switch through a test wire (1) to transmit the resistance data obtained from the test to the electrical measuring instrument. The side of the changeover switch connecting plate (6) where the test wire (1) is connected and the side of the temperature sensing element connecting plate (5) where the element to be tested (8) is connected are fitted together by fasteners.

2. The testing device for an industrial resistance temperature sensing element according to claim 1, characterized in that, The conductor layer is made of copper or silver.

3. The testing device for an industrial resistance temperature sensing element according to claim 1, characterized in that, The insulating substrate (2) of the temperature sensing element connecting plate (5) is provided with conductor layers on both the upper and lower sides, and the insulating substrate (2) of the changeover switch connecting plate (6) is provided with a conductor layer on one side. The conductor layer includes a first conductor layer (3) and a second conductor layer (4), and the first conductor layer (3) and the second conductor layer (4) are located on the left and right sides of the connecting plate, respectively. The conductor layers on both sides of the temperature sensing element connecting plate (5) are in contact with the conductor layer of the changeover switch connecting plate (6).

4. The testing device for an industrial resistance temperature sensing element according to claim 1, characterized in that, Two test wires (1) are welded to the first conductor layer (3) and the second conductor layer (4) of the switching connection plate (6).

5. The testing device for an industrial resistance temperature sensing element according to claim 1, characterized in that, The connecting plate is arranged in the form of a long strip.

6. A method for measuring the resistance value of a temperature-sensing element using the testing apparatus as described in claim 1, characterized in that, Includes the following steps: 1) Crim one end of the two leads of the component under test onto the connection plate of the test device and connect it to the test lead; 2) Measure the resistance value of the temperature sensing element.

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