Quick-response platinum resistor temperature sensor

Abstract

A fast response platinum resistor temperature sensor comprises a sensor housing, a measuring end of the sensor housing is provided with a sensor element, the sensor element comprises a ceramic cylinder, a front end of the ceramic cylinder is provided with packaging ceramic, the packaging ceramic is provided with a plurality of through holes, a rear end of the ceramic cylinder is provided with heat conduction ceramic, and the heat conduction ceramic is provided with a plurality of through holes. A temperature measuring platinum wire is arranged at the upper end of the interior of the ceramic cylinder and connected with a platinum resistor lead, a thermoelectric material wire is arranged at the lower end of the interior of the ceramic cylinder, the front end of the thermoelectric material wire is welded with a leading-out wire to form a second hot junction, and the rear end of the thermoelectric material wire is welded with another leading-out wire to form a first hot junction. The lead-out wire penetrates through a through hole in the packaging ceramic, the platinum resistor lead is connected with a platinum resistor signal lead arranged in the sensor shell, the lead-out wire is connected with a thermoelectric material wire signal lead, the platinum resistor signal lead and the thermoelectric material wire signal lead are fixedly connected with a sensor junction box, and the sensor shell is filled with an insulating material.

Description

Technical Field

[0001] The invention relates to the technical field of temperature measurement, and in particular to a fast-response platinum resistance temperature sensor. Background Art

[0002] In traditional temperature measurement technology, thermocouples and platinum resistance are two commonly used temperature measuring elements. Thermocouples use the thermoelectric effect to measure temperature, and have the characteristics of a wide measurement range and fast response speed, but the accuracy is affected by many factors. Platinum resistance is known for its high accuracy and stability, but the response speed is relatively slow. The temperature sensors currently used usually use thermocouples to measure temperature, and high-precision platinum resistance is used at the cold end of the thermocouple for compensation. It is not possible to directly use platinum resistance for high-precision and fast measurement.

[0003] Therefore, a temperature sensor with high measurement accuracy and fast response is needed. Summary of the invention

[0004] The purpose of the present invention is to provide a fast-response platinum resistance temperature sensor to address the corresponding deficiencies of the prior art. The temperature sensor can accurately measure the temperature and respond quickly.

[0005] The object of the present invention is achieved by adopting the following scheme: a fast response platinum resistance temperature sensor, comprising a sensor housing, a sensor element is arranged at the measuring end of the sensor housing, a sensor junction box is arranged at the front end of the sensor housing, the sensor element is connected to the sensor junction box through a signal lead, the sensor element comprises a ceramic cylinder, a packaging ceramic is arranged at the front end of the ceramic cylinder, a plurality of through holes are arranged on the packaging ceramic, a thermal conductive ceramic is arranged at the rear end of the ceramic cylinder, a temperature measuring platinum wire is arranged at the upper end of the interior of the ceramic cylinder, the rear end of the temperature measuring platinum wire is arranged in the thermal conductive ceramic, the front end of the temperature measuring platinum wire passes through two through holes on the packaging ceramic to form a U-shaped loop and connects with the platinum The resistor lead is connected, a thermoelectric material wire is arranged at the lower end of the inner part of the ceramic cylinder, the front end of the thermoelectric material wire is located in the middle of the ceramic cylinder and is welded with a lead wire to form thermal node 2, the rear end of the thermoelectric material wire is arranged in the thermal conductive ceramic and is welded with another lead wire to form thermal node 1, the lead wire passes through the through hole on the packaging ceramic, the platinum resistor lead is connected with the platinum resistor signal lead arranged in the sensor housing, the lead wire is connected with the thermoelectric material wire signal lead, the platinum resistor signal lead and the thermoelectric material wire signal lead pass through the seal arranged at the front end of the sensor housing and are connected and fixed to the sensor junction box, and the sensor housing is filled with insulating material to fix the sensor element.

[0006] The thermoelectric material wire is a metal, alloy or semiconductor material with high thermoelectric effect.

[0007] The temperature measuring platinum wire is a pure platinum wire.

[0008] The platinum resistance lead wires are respectively connected to two platinum resistance signal lead wires.

[0009] The sensor housing is a stainless steel housing.

[0010] The ceramic cylinder, packaging ceramic and thermal conductive ceramic are nano-ceramics.

[0011] The advantages of the present invention are: 1. The present invention combines the advantages of thermocouples and platinum resistors, has both the fast response characteristics of thermocouples and the high precision and stability of platinum resistors, and improves the accuracy and reliability of temperature measurement.

[0012] 2. By sintering a high thermal conductivity nano-thermal conductive ceramic material on the exposed end surface of the thermoelectric material, the heat conduction efficiency is enhanced, so that the thermal node of the thermoelectric material can respond to temperature changes more quickly, thereby improving the response speed of temperature measurement.

[0013] 3. The temperature sensor element of the present invention has a simple structure, a small volume, and is easy to manufacture and install. After the temperature measuring element is packaged as a whole, its appearance is the same as that of a conventional platinum resistance element, and it is suitable for various temperature measurement occasions.

[0014] 4. Although the temperature sensor of the present invention has a thermocouple for temperature measurement, it measures the relative temperature difference, so the signal lead wire is a signal lead wire of the same material. Unlike conventional thermocouple temperature sensors, cold end compensation is not required. Therefore, the six signal lead wires in the temperature sensor are all made of the same silver wire material, and the preparation process is the same as that of conventional platinum resistance temperature sensors, without increasing the manufacturing difficulty.

[0015] 5. The temperature sensor of the present invention only needs to add the temperature measured by the platinum resistor and the temperature difference measured by the thermoelectric material wire during signal processing. The temperature difference is positive when the temperature rises instantly, and negative when the temperature drops instantly. When the temperature balance is reached, the temperature difference is basically 0, realizing high-precision temperature measurement of the platinum resistor. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the structure of the present invention; Figure 2 It is a schematic diagram of the structure of the sensor element; Figure 3 is a side view of the sensor element; Figure 4 It is a schematic diagram of the principle of the present invention. DETAILED DESCRIPTION

[0017] like Figures 1 to 3As shown, a fast response platinum resistance temperature sensor includes a sensor housing 11, and the sensor housing 11 is a stainless steel housing. A sensor element 13 is arranged at the measuring end of the sensor housing 11, and a sensor junction box 16 is arranged at the front end of the sensor housing 11. The sensor element 13 is connected to the sensor junction box 16 through a signal lead. The sensor element 13 includes a ceramic cylinder 2, and a packaging ceramic 8 is arranged at the front end of the ceramic cylinder 2. A plurality of through holes are arranged on the packaging ceramic 8, and a thermal conductive ceramic 5 is arranged at the rear end of the ceramic cylinder 2. The ceramic cylinder 2, the packaging ceramic 8 and the thermal conductive ceramic 5 are nano-ceramics. A temperature measuring platinum wire 3 is arranged at the upper end of the interior of the ceramic cylinder 2, and the temperature measuring platinum wire 3 is a pure platinum wire. The rear end of the temperature measuring platinum wire 3 is arranged in the thermal conductive ceramic 5, and the front end of the temperature measuring platinum wire 3 passes through the two through holes on the packaging ceramic 8 to form a U-shaped loop and is connected to the platinum resistance lead 1. A thermoelectric material wire 4 is arranged at the lower end of the interior of the ceramic cylinder 2, and the thermoelectric material wire 4 is a metal or alloy with a high thermoelectric effect. The front end of the thermoelectric material wire 4 is located in the middle of the ceramic cylinder 2 and is welded to a lead wire 9 to form a thermal node 2 7. The rear end of the thermoelectric material wire 4 is arranged in the thermal conductive ceramic 5 and is welded to another lead wire 9 to form a thermal node 1 6. The lead wire 9 passes through the through hole on the packaging ceramic 8. The platinum resistance lead wire 1 is connected to the platinum resistance signal lead wire 12 arranged in the sensor housing 11. The platinum resistance lead wire 1 is respectively connected to two platinum resistance signal leads 12. The lead wire 9 is connected to the thermoelectric material wire signal lead wire 14. The platinum resistance signal lead wire 12 and the thermoelectric material wire signal lead wire 14 pass through the seal 18 arranged at the front end of the sensor housing 11 and are connected and fixed to the sensor junction box 16. The sensor housing 11 is filled with insulating material 15 to fix the sensor element 13. The platinum resistance signal lead wire 12 and the thermoelectric material wire signal lead wire 14 are made of metal materials other than the thermoelectric material 4 and the temperature measuring platinum wire 3.

[0018] When the sensor measures the temperature, the measuring end of the sensor is contacted with the temperature measuring medium, and the heat is transmitted to the high thermal conductivity thermal ceramic 5 through the sensor housing 11 at the measuring end. Due to the high thermal conductivity of the nano-ceramic material, the temperature at the hot junction 1 6 rises instantly, while the temperature at the hot junction 2 7 is still in the original temperature state, and the temperature of the temperature measuring platinum wire 3 has not yet reached thermal equilibrium due to its long volume. Therefore, at this time, the two ends of the thermoelectric material wire 4 generate a temperature difference potential, which is recorded as Δe, and the temperature difference temperature value can be calculated as ΔT. At the same time, the temperature measuring platinum wire 3 is also tested to obtain a temperature b degree. According to the design principle of the present invention, the actual temperature T at this time is T=ΔT+b. When the temperature at both ends of the thermoelectric material wire 4 reaches equilibrium, the temperature at the temperature measuring platinum wire 3 is the same as the external environment. At this time, the temperature difference value ΔT=0, and the temperature measurement is mainly carried out by the temperature measuring platinum wire 3. At this time, the actual temperature T is equal to the temperature b measured by the temperature measuring platinum wire 3, realizing fast and high-precision temperature measurement. The thermoelectric material wire plays the function of temperature compensation when the temperature changes sharply.

[0019] The principle of the present invention is as follows Figure 4 As shown, the temperature T1 is the hot junction 1 6, and the thermal conductive ceramic 5 at the bottom of the sensor element 13 is in contact with the medium first. The temperature T2 is the hot junction 2 7 in the middle of the ceramic cylinder, and the temperature here is the same as the temperature of the temperature measuring platinum wire 3. The temperature T3 is the packaging ceramic 8 of the sensor element 13.

[0020] A is the thermoelectric material wire 4; B, C1, C2 are lead wires 9, B, C1, C2 are made of the same material, and C1 and C2 are the same wire without a solder joint in the middle. The principle realization derivation process is as follows: The total thermoelectric potential of this circuit is: Formula 1-1; Assuming that the temperature of each connection point is the same, the total thermoelectric potential of the circuit is zero, that is, Formula 1-2; Right now: Formula 1-3; Substituting equation 1-3 into equation 1-1, we get = +

[0021] Since B and C2 have the same lead wire, , so, Formula 1-4; The potential value obtained at T3 is the temperature difference between T1 and T2 of the thermocouple composed of the lead wire of section C1 and the thermoelectric material wire A, which is recorded as Δe, that is, Δe= , it can be seen from the equation that Δe is independent of the temperature at T3.

[0022] The temperature at T2 is the same as the temperature value tested by the temperature measuring platinum wire. Therefore, since the thermocouple metal material A and the material of the lead wire C1 are known, the thermoelectric electromotive force rate (Seebeck coefficient) of the thermocouple composed of these two materials can be known. The temperature value at T2 can be measured by the platinum resistance temperature value, and the temperature difference can be obtained and recorded as ΔT. This temperature difference plus the temperature value tested by the temperature measuring platinum wire is the actual temperature value at this moment.

[0023] Assume that the Seebeck coefficient of the thermocouple composed of A-C1 is S AC1 , the temperature value measured by the platinum wire is T2, then T1=Δe / S AC1 (T2)+ T2.

[0024] The process of using this temperature sensor to achieve high-precision and rapid temperature measurement is as follows: Example 1

[0025] The temperature measuring platinum wire uses PT100 platinum resistance wire, and the thermoelectric material wire uses the negative electrode NiAl of K-type couple wire. A temperature sensor with an outer diameter of 8.0 mm is prepared.

[0026] The temperature sensor with an ambient temperature of about 21℃ is quickly inserted into hot water. At 0.5 seconds, the temperature value measured by the platinum resistance is 40℃. At this time, the thermoelectric potential Δe=0.51Mv=510μV. By querying, it is found that the Seebeck coefficient S=10.2μv / ℃ of NiAl-Pt at this time, and the temperature difference is ΔT=510 / 10.2=50℃, so the actual temperature value T=40℃+50℃=90℃, which is the same as the actual hot water temperature value of 90℃. Of course, as the insertion time increases, the thermoelectric potential will decrease. Finally, Δe tends to 0, and the temperature value measured by the platinum resistance is close to 90℃. But this time is relatively long. For the temperature sensor with an outer diameter of 8.0mm, when the temperature measured by the platinum resistance reaches the real hot water temperature of 90℃, this time takes 28 seconds, which is the response time of the traditional platinum resistance temperature sensor.

[0027] However, when the temperature sensor of the present invention is used, the comprehensive temperature output value of the platinum resistor at 0.5 seconds is displayed as 90° C., so the response time is greatly improved. Example 2

[0028] Similarly, the lead wire 9 is replaced with the positive electrode NiCr of the K-type thermocouple. The thermoelectric material wire 4 uses the negative electrode NiAl of the K-type thermocouple wire. Similarly, a temperature sensor with an outer diameter of 8.0 mm is prepared.

[0029] The temperature sensor with an ambient temperature of about 21℃ is quickly inserted into the oven. At about 4.2s, the temperature value measured by the platinum resistance is 46℃. At this time, the thermoelectric potential Δe=3.04584mV=3045.84μV. By querying, it is found that the Seebeck coefficient S of NiCr-NiAl at this time is 41.16μv / ℃, and the temperature difference is ΔT=3045.84 / 41.16=74℃, so the actual temperature value T=46℃+74℃=120℃, which is the same as the actual oven temperature value of 120℃. Similarly, as the insertion time increases, the thermoelectric potential will decrease, and finally Δe tends to 0, and the temperature value measured by the platinum resistance is close to 120℃. But this time is relatively long. For the composite temperature sensor with an outer diameter of 8.0mm, when the temperature measured by the platinum resistance reaches the actual oven temperature of 120℃, this time is about 57 seconds, which is the response time of the traditional platinum resistance temperature sensor.

[0030] However, when the temperature sensor of the present invention is used, the comprehensive temperature output value of the platinum resistor is displayed as 120° C. at 4.2 seconds, so the response time is greatly improved.

[0031] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification 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 fast response platinum resistance temperature sensor, comprising a sensor housing (11), a sensor element (13) being arranged at a measuring end of the sensor housing (11), a sensor junction box (16) being arranged at a front end of the sensor housing (11), the sensor element (13) being connected to the sensor junction box (16) via a signal lead, characterized in that: The sensor element (13) comprises a ceramic cylinder (2), a packaging ceramic (8) is arranged at the front end of the ceramic cylinder (2), a plurality of through holes are arranged on the packaging ceramic (8), a heat-conducting ceramic (5) is arranged at the rear end of the ceramic cylinder (2), a temperature measuring platinum wire (3) is arranged at the upper end of the interior of the ceramic cylinder (2), the rear end of the temperature measuring platinum wire (3) is arranged in the heat-conducting ceramic (5), the front end of the temperature measuring platinum wire (3) passes through two through holes on the packaging ceramic (8) to form a U-shaped loop and is connected to the platinum resistance lead wire (1), a thermoelectric material wire (4) is arranged at the lower end of the interior of the ceramic cylinder (2), the front end of the thermoelectric material wire (4) is located in the middle of the ceramic cylinder (2) and is welded to a lead wire (9) to form a thermal node Second (7), the rear end of the thermoelectric material wire (4) is arranged in the thermal conductive ceramic (5) and welded with another lead wire (9) to form a thermal node one (6), the lead wire (9) passes through the through hole on the packaging ceramic (8), the platinum resistance lead wire (1) is connected to the platinum resistance signal lead wire (12) arranged in the sensor housing (11), the lead wire (9) is connected to the thermoelectric material wire signal lead wire (14), the platinum resistance signal lead wire (12) and the thermoelectric material wire signal lead wire (14) pass through the seal (18) arranged at the front end of the sensor housing (11) and are connected and fixed to the sensor junction box (16), and the sensor housing (11) is filled with insulating material (15) to fix the sensor element (13).

2. A fast response platinum resistance temperature sensor according to claim 1, characterized in that: The thermoelectric material wire (4) is a metal, alloy or semiconductor material with a high thermoelectric effect.

3. The fast response platinum resistance temperature sensor according to claim 1, characterized in that: The temperature measuring platinum wire (3) is a pure platinum wire.

4. The fast response platinum resistance temperature sensor according to claim 1, characterized in that: The platinum resistance lead wire (1) is respectively connected to two platinum resistance signal lead wires (12).

5. The fast response platinum resistance temperature sensor according to claim 1, characterized in that: The sensor housing (11) is a stainless steel housing.

6. The fast response platinum resistance temperature sensor according to claim 1, characterized in that: The ceramic cylinder (2), the packaging ceramic (8) and the thermally conductive ceramic (5) are nano-ceramics.

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