A filled material liquid temperature sensor

Abstract

The present application belongs to the technical field of sensor preparation, and relates to a filling material type liquid temperature sensor. A liquid with a known concentration is selected as a conductive medium, the conductivity of the liquid changes linearly with temperature when the temperature changes, the voltage change of the constant current applied to the electrodes on both ends of the liquid is measured, the resistance change is obtained, and the temperature change is deduced. In the shell, the influence of the inaccuracy of the test caused by the bubbles generated by the long-time placement of the liquid can be eliminated by the compact filler such as the packaging gauze. The main structure of the sensor includes a shell, a liquid with a known conductivity and resistance in the shell, a filler, waterproof glue, electrodes, electrode connecting pieces and wires, and the sensor product is packaged by electrically connecting each component. The sensor has the advantages of simple structure, small size, high precision, high stability, good integration and the like, and can be widely used in the fields of temperature detection such as physics, biology, chemistry, ocean exploration and spaceflight, and is environmentally friendly.

Description

Technical fields:

[0001] This invention belongs to the field of sensor fabrication technology and relates to the structural design of a liquid temperature sensor with a filling material. It achieves temperature measurement based on the characteristic that the conductivity of a liquid changes linearly with temperature. The filling material eliminates the influence of bubbles generated when the liquid is left for a long time, which would lead to inaccurate testing. Background technology:

[0002] Temperature is a crucial and unique fundamental physical quantity, and thermometry is an important branch of metrology. Every stage of scientific research and industrial and agricultural production relies on reliable and accurate temperature measurement. Accurate temperature measurement is closely related to the external environment in which the temperature sensor operates, such as pressure and surrounding conditions. Traditional temperature-sensing elements, such as thermistors, thermocouples, and platinum resistance thermometers, convert the sensed temperature into a resistance value for measurement, and then calibrate it by comparing and interpolating with a metrology-grade standard temperature source. According to the definition of resistance… A thermistor with a length L and a cross-sectional area S exhibits resistivity that changes with temperature. Conductivity and resistance are the reciprocals of resistance and resistivity, respectively. Changes in length L or S directly affect the resistance value. During manufacturing, process tolerances or variations between different batches can cause inconsistencies in the resistance values ​​of individual thermistors, making calibration difficult. High-temperature processes during manufacturing can accumulate stress on the thermistor. Although annealing processes exist, residual stress gradually dissipates during application, leading to resistance drift. Furthermore, harsh operating environments, such as external high pressure, can also create stress on the thermistor, causing resistance drift. All these factors contribute to measurement errors. Therefore, it is necessary to invent a temperature sensor that does not accumulate stress during manufacturing or application, and whose inaccurate measurements are not caused by stress.

[0003] The conductivity of many liquids changes linearly with temperature. Theoretically, liquids are incompressible and do not accumulate stress during manufacturing or application. A liquid of known concentration and conductivity is placed in an insulating housing. A pair of electrodes is applied to the two ends of the liquid, and a constant voltage (or current) is applied to the electrodes. The change in current (or voltage) is measured, converted into a change in conductivity, and then used to deduce the temperature change, achieving accurate temperature detection. Alternatively, a pair of current electrodes is applied to the two ends of the liquid, and a constant current is applied to them; a pair of voltage electrodes are applied to the middle section of the liquid, and the change in voltage is measured. The measured resistance is converted into a change in conductivity, and then used to deduce the temperature change, achieving accurate temperature detection. Ordinary liquid temperature sensors, after prolonged placement, will generate many small bubbles in the tube. Initially, these small bubbles have no effect on the test, but over time, they will slowly converge and move, eventually forming a large bubble. If this large bubble moves in the tube, it will affect the internal electric field, leading to inaccurate measurements. Therefore, preventing the formation and movement of large bubbles is crucial for the long-term stability of liquid sensor measurements. By encapsulating the tube with a tightly packed filling material, the formation of air bubbles can be effectively prevented. Even if small air bubbles appear, the filling material, due to its tightness, will prevent the movement of small air bubbles and fix them in place, preventing the formation of oversized air bubbles. This ensures that the test is not affected by these air bubbles, making the long-term test results more accurate.

[0004] Chinese Patent 2020108404600 discloses a spiral-type liquid conductivity adjustable temperature sensor. Its main structure is a four-electrode structure with a cavity structure. This not only allows for highly accurate conductivity calibration by changing the distance between the electrodes but also effectively eliminates measurement errors caused by polarization effects, making temperature measurements more accurate. Unlike elongated temperature sensing heads, the spiral cavity structure flattens the sensing head, reducing its length and providing flexibility for complex environments. The four-electrode spiral-type liquid conductivity adjustable temperature sensor has two current electrodes located at the beginning and end of the spiral structure, respectively, and two voltage electrodes located in the middle of the spiral cavity. The positions of the two current electrodes and two voltage electrodes can be flexibly adjusted, thereby changing the distance between the electrodes and altering the voltage drop of the liquid within the cavity, thus changing the resistance value and achieving adjustable resistance. Its main structure includes a lower base, liquid, electrodes, and a spiral cavity. A spiral cavity is formed on a square or round plate-shaped lower base, with voltage electrodes fixed at corresponding positions within the cavity. Current electrodes are fixed on the inner sides of the inner and outer ends of the spiral cavity. The cavity is filled with liquid, and an upper base is sealed on the upper side of the cavity. The upper and lower bases correspond in structure and are sealed together to form a closed, box-like spiral cavity. Two current electrodes are located at the inner end of the starting point and the outer end of the ending point of the spiral cavity, respectively, and their positions can be adjusted within a small range. The two current electrodes are connected by wires, passing through the lower base and leading out. Two voltage electrodes are located in the middle of the spiral cavity and their positions are adjustable. The two voltage electrodes are connected by wires, passing through the lower base and leading out. The conductivity of the liquid can be adjusted by directly adjusting the relative positions of the two voltage electrodes, achieving adjustable conductivity. This technology can be applied to electrocardiogram (ECG), blood pressure monitors, and pulsometers in the medical field for cardiac function testing.

[0005] Chinese Patent No. 202010840448X discloses an in-situ self-calibrating temperature sensing device. Its main structure includes a housing, a power module, a control and calibration circuit module, a communication circuit module, an electronic switch, wires, and a miniature water three-phase point bottle. All components are electrically connected and fixedly assembled within the waterproof and sealed housing, forming an integrated sensor structure. The temperature measurement sensing probe is electrically connected and positioned at the outer end of the housing, forming the in-situ self-calibrating temperature sensing device. The temperature measurement sensing probe is led out via wires and positioned at the outer end of the pressure-resistant housing. Other components and circuits are electrically connected and integrated within the housing. The temperature measurement sensing head is electrically connected to both a miniature water temperature calibration sensing head and a miniature gallium temperature calibration sensing probe. These three sensors are selected and compared at the factory to ensure that their performance is completely consistent, enabling temperature measurement and calibration.

[0006] The existing sensors described above have limited application scope, are not suitable for specific occasions, and their accuracy and cost are insufficient for applications in marine and other environments. Therefore, developing a new type of liquid conductivity sensor has good market prospects. Summary of the Invention:

[0007] The purpose of this invention is to overcome the shortcomings of existing technologies. By combining the linear change of conductivity with temperature characteristic of liquid conductivity sensors, this invention utilizes a liquid of known concentration as the sensing element, making it unaffected by stress. The tightly packed filling material inside the cavity reduces the influence of air bubbles in the water on the measurement, thereby achieving long-term stable and accurate temperature measurement. A liquid temperature sensor with a filling material is designed, which is not only unaffected by external stress, but also effectively prevents the aggregation of air bubbles in the liquid, thus making temperature testing more accurate.

[0008] To achieve the above objectives, the main structure of the liquid temperature sensor with filling material according to the present invention includes waterproof adhesive, electrodes, electrode connectors, a housing, filler, a water inlet, a conductive liquid, and wires. Two electrodes of a symmetrical structure are fixedly inserted into both ends of a hollow cylindrical housing via electrode connectors. Wires for transmitting electrical information are welded to the exposed ends of the two electrodes. Grooves are formed on the end faces of the two electrode connectors of the symmetrical structure. Waterproof adhesive filled in the grooves fixes and insulates the electrodes and wires. Waterproof adhesive is also used between the electrode connectors and the housing. The same type of adhesive is used for bonding; the filler is tightly sealed in the shell, and the upper side of the shell has a water inlet. The sealed water inlet is used to fill the conductive liquid of known concentration. After filling, the water inlet is sealed again; after the conductive liquid is sealed into the shell, the filler is submerged in the conductive liquid with known conductivity and resistance; the inductive conductive electrode contacts the conductive liquid to form an electric field circuit; the hollow cylindrical shell is connected to the electrode connector through waterproof adhesive to achieve electrical information connection, and the electrodes and electrode connectors are connected in a sealed manner through ceramic glaze; all connection parts should be sealed and airtight.

[0009] The conductive liquid involved in this invention is a conductive liquid composed of salt water and alcohol in any proportion and at different concentrations; its temperature measurement range is between the freezing point and vapor point of the conductive liquid, including -117.3°C to 100°C.

[0010] The shell involved in this invention is made of thermally conductive material, including ceramics, metals, quartz, polytetrafluoroethylene, polymer materials, and plastics, with sizes ranging from nanometers to tens of centimeters. The shell has insulation properties both inside and out, and the insulation method includes insulation of the outer layer of the shell material itself or coating the shell wall with an insulating material. The shape of the shell includes cylindrical, cuboid, or other shapes, and the shape of the electrode connector varies according to the shape of the shell. The filling liquid inside the shell cavity also includes conductive liquids such as oil, acetone, and methanol.

[0011] The materials used for the electrode connectors involved in this invention include ceramic and quartz insulating materials.

[0012] The waterproof adhesives involved in this invention include casting adhesives, epoxy resin adhesives, and UV adhesives, which are adhesive compounds with strong waterproofing function.

[0013] The encapsulation filler of the present invention is a small-volume material that is thermally conductive, non-absorbent, and does not react with conductive liquids, and can be tightly arranged, including mesh and small-diameter particles.

[0014] The electrode used in this invention includes platinum electrodes, stainless steel electrodes, or other materials with similar properties; the electrode shape includes cylindrical, dot-shaped, sheet-shaped, packaged, or other shapes that can achieve the same function; when a constant AC excitation is applied to both ends of the current conduction electrode, the voltage of the two electrodes is measured, and the change in voltage drop reflects the change in conductivity of the conductive liquid with temperature, thereby deriving the temperature change; thus achieving accurate and stable temperature measurement under external high pressure.

[0015] Compared with existing temperature sensors, this invention utilizes the incompressibility of the liquid involved, which makes it unaffected by external and internal stresses, thus avoiding temperature errors caused by stress. The internal filling material ensures that air bubbles in the water have no impact on the test, making the temperature test more accurate. It has the advantages of simple structure, small size, high precision, high stability, and good integration, and has important practical value for temperature detection in fields such as physical, biological and chemical sensing, marine exploration, and aerospace. It is also environmentally friendly. Attached image description:

[0016] Figure 1 This is a schematic diagram illustrating the structural principle of the liquid temperature sensor with filling material involved in this invention. Detailed implementation method:

[0017] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0018] Example 1:

[0019] The structure of the filled material type liquid temperature sensor involved in this embodiment is shown in the attached figure. Figure 1As shown, its main structure includes waterproof adhesive 1, electrodes 2, electrode connectors 3, housing 4, filler 5, water inlet 6, conductive liquid 7, and wires 8; the two electrodes 2 of the symmetrical structure are fixedly inserted into the two ends of the hollow cylindrical housing 4 through the electrode connectors 3, and the wires 8 for transmitting electrical information are respectively welded to the exposed ends of the two electrodes 2; the end faces of the two electrode connectors 3 of the symmetrical structure are respectively provided with groove structures, and the waterproof adhesive 1 filled in the groove structures fixes and connects the electrodes 2 and the wires 8 and insulates them from the outside; the electrode connectors 3 and the housing 4 are also bonded with the same type of adhesive as the waterproof adhesive 1; filler 5 The liquid is tightly encapsulated in a housing 4. An inlet 6 is formed on the upper side of the housing 4. The sealed inlet 6 is used to fill a conductive liquid 7 of known concentration. After filling, the inlet 6 is sealed again. After the conductive liquid 7 is encapsulated in the housing 4, the filler 5 is submerged in the conductive liquid 7 with known conductivity and resistance. The inductively conductive electrode 2 contacts the conductive liquid 7 to form an electric field circuit. The hollow cylindrical housing 4 is connected to the electrode connector 3 by the adhesive 1 of waterproof adhesive. The electrode 2 and the electrode connector 3 are connected in a sealed manner by ceramic glaze. All connection parts should be sealed and airtight.

[0020] The conductive liquid 7 involved in this embodiment is a conductive liquid that is a mixture of salt water and alcohol in any proportion and concentration; its temperature measurement range is between the freezing point and the vapor point of the conductive liquid 7, including -117.3°C to 100°C.

[0021] The housing 4 involved in this embodiment is made of a thermally conductive material, including ceramics, metals, quartz, polytetrafluoroethylene, polymer materials and plastics with thermal conductivity ranging from 0.1W / mK to 450W / mK, and sizes ranging from nanometers to tens of centimeters. The housing 4 has electrical insulation both inside and out, and the insulation method includes the outer layer of the housing 4 material itself being insulated or the wall of the housing 4 being coated with a layer of electrical insulating material. The shape of the housing 4 includes cylindrical, cuboid or other shapes, and the shape of the electrode connector 3 varies according to the shape of the housing 4. The filling liquid in the cavity of the housing 4 also includes conductive liquids such as oil, acetone and methanol.

[0022] The electrode connector 3 involved in this embodiment is made of ceramic and quartz insulating materials.

[0023] The waterproof adhesives involved in this embodiment include epoxy resin adhesives, UV adhesives, or casting adhesives, which are adhesive compounds with strong waterproofing function.

[0024] The encapsulation filler 5 involved in this embodiment is a small-volume material that is thermally conductive, non-absorbent, and does not react with the conductive liquid 7, and can be tightly arranged, including mesh, capillaries, and small-diameter particles.

[0025] The electrode 2 involved in this embodiment uses materials including platinum electrodes, stainless steel electrodes, or other materials with the same properties; the shape of the electrode 2 includes cylindrical, dot-shaped, sheet-shaped, packaged, or other shapes that can achieve the same function.

[0026] The electrode 2 used for current conduction in this embodiment, when a constant AC excitation is applied to both ends of the electrode 2, the voltage of the two electrodes 2 is measured. The change in voltage drop reflects the change in conductivity of the conductive liquid 7 with temperature, thereby deriving the temperature change; thus achieving accurate and stable temperature measurement under external high pressure.

[0027] Example 2:

[0028] This embodiment relates to an application example of the sensor of Embodiment 1. The sensor prepared in the embodiment is applied to the measurement of seawater ambient temperature in the deep sea. After measurement and analysis, its temperature parameters are stable and can achieve long-term temperature measurement stability of better than 2mK and above.

Claims

1. A liquid temperature sensor filled with a material, characterized in that, The main structure includes waterproof adhesive, electrodes, electrode connectors, a housing, filler, a water inlet, conductive liquid, and wires. Two electrodes in a symmetrical structure are fixedly inserted into both ends of a hollow cylindrical housing via electrode connectors. Wires for transmitting electrical information are soldered to the exposed ends of the two electrodes. Grooves are formed on the end faces of the two electrode connectors in the symmetrical structure. Waterproof adhesive filled in these grooves fixes and connects the electrodes and wires, while also insulating them from the outside. The electrode connectors and the housing are also bonded using a similar adhesive to the waterproof adhesive. The material involved is a small-volume material that is thermally conductive, non-hygroscopic, and does not react with conductive liquids. This material, including mesh and small-diameter particles, is tightly encapsulated in a shell. An inlet is located on the upper side of the shell. This sealed inlet is used to fill conductive liquids such as mixtures of salt water and alcohol of different concentrations, as well as oil, acetone, and methanol. After filling, the inlet is sealed again. Once the conductive liquid is encapsulated in the shell, the filler is submerged in the conductive liquid with known conductivity and resistance. Inductively conductive electrodes contact the conductive liquid to form an electric field circuit. The hollow cylindrical shell is bonded to the electrode connectors with waterproof adhesive to achieve electrical information connection. A ceramic glaze is used to achieve a sealed connection between the electrodes and the electrode connectors. All connections must be airtight.

2. The liquid temperature sensor with filling material according to claim 1, characterized in that, The housing involved is made of thermally conductive material, and both the inside and outside of the housing are insulated. The insulation methods include the outer layer of the housing material itself being insulated or the housing wall being coated with an insulating material; the shape of the electrode connectors varies according to the shape of the housing.

3. The liquid temperature sensor with filling material according to claim 1, characterized in that, The electrodes involved include platinum electrodes or stainless steel electrodes, or other electrode materials with similar properties; the electrode shapes include cylindrical, dot-shaped, sheet-shaped, or other shapes that can achieve the same function; when a constant AC excitation is applied to the two ends of the current conduction electrode, the voltage between the two electrodes is measured, and the change in voltage drop reflects the change in conductivity of the conductive liquid with temperature, and the temperature change is deduced; accurate and stable temperature measurement under external high pressure is achieved.

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