Thermocouple for thermal environment test of aircraft

Abstract

The utility model relates to a thermocouple, in particular to a thermocouple for an aircraft thermal environment test. The thermocouple is composed of a temperature measurement electrode, a magnetic insulation tube, a protection layer and a high-temperature heat insulation layer, the temperature measurement electrode is wrapped with the magnetic insulation tube, the protection layer is sleeved on the magnetic insulation tube, and the outer side of the protection layer is sleeved with a single-layer or multi-layer high-temperature heat insulation layer. The thermocouple can effectively block heat transfer through the high-temperature heat insulation layer, and can effectively ensure the performance of the magnetic insulation tube through the high-temperature protection layer, so that the temperature measurement of the temperature measurement electrode is accurate, and the thermal environment accuracy of a test piece is ensured. The high-temperature thermal insulation layer is obtained by weaving the quartz fibers, so that the flexibility of the high-temperature thermal insulation layer can be effectively ensured, and the high-temperature thermal insulation layer can be bent, so that the thermocouple can adapt to the surface arrangement of a special-shaped test piece, and the universality of the thermocouple is effectively improved. The problems that an existing thermocouple is poor in high temperature resistance and cannot have high temperature resistance and flexibility at the same time are solved.

Description

Technical Field

[0001] The utility model relates to a thermocouple, in particular to a thermocouple for aircraft thermal environment tests. Background Art

[0002] Thermal environment test refers to heating a test piece to reach the thermal environment state required by the design, and conducting thermal load assessment and force load assessment on the test piece in this thermal environment. In thermal environment tests, thermocouples are generally used to measure the temperature of the thermal environment test. According to the temperature fed back by the thermocouple to the temperature control system, the parameters of its control system are appropriately adjusted to achieve the purpose of controlling the thermal environment state of the test piece.

[0003] The K-type thermocouple is a commonly used temperature measuring element in temperature measuring instruments. It directly measures the temperature, converts the temperature signal into a thermal electromotive force signal, and converts it into the temperature of the measured thermal environment medium through an electrical instrument. The shape of the K-type thermocouple varies according to different usage requirements, but its basic structure is roughly the same. It generally consists of main components such as a temperature sensing element, a mounting and fixing device, and a junction box, and is usually used in combination with display instruments, recording instruments, and electronic regulators. Due to its advantages such as stable performance, accurate and reliable, simple structure, convenient use, wide temperature measurement range, and remote signal transmission, the K-type thermocouple has become the most widely used temperature sensing element in the fields of industrial production and scientific research. During its temperature measurement process, the protective sleeve of the K-type thermocouple plays an important role.

[0004] When the existing insulation protection layer of the K-type thermocouple is performing temperature measurement work, affected by the thermal radiation in the thermal environment area, the insulation protection layer is prone to conduct heat to the inside, and the temperature is detected by the temperature measuring electrode at the end of the magnetic insulation tube. When the magnetic insulation tube contacts the inner wall of the protective sleeve that has been heated for a long time, its service life will be affected. When using a conventional K-type thermocouple for thermal environment tests, when the thermal environment test temperature reaches 600 to 700 °C, due to the fact that the insulation protection layer of the K-type thermocouple cannot effectively block the thermal radiation of the thermal environment to the K-type thermocouple, its temperature measurement is affected or even itself is damaged, resulting in the temperature control system being unable to obtain correct temperature feedback information. And the required thermal environment temperature of the test piece during the experiment needs to reach about 1000 °C, which is much higher than 700 °C, resulting in the damage of the magnetic insulation tube when using a conventional K-type thermocouple, and thus easily causing inaccurate temperature measurement, resulting in the thermal environment where the test piece is located not reaching the thermal environment state required by the design. In addition, most of the existing protective sleeves are made of glass fiber / ceramic matrix or polytetrafluoro materials, which have heat insulation and insulation properties to a certain extent, but have certain limitations: the glass fiber / ceramic matrix is mainly reflected in the hard material and is not easy to bend, and the polytetrafluoro material is reflected in poor heat resistance. Therefore, there is an urgent need to design a thermocouple for thermal environment tests to solve the above problems. Summary of the Invention

[0005] The object of the present utility model is to provide a thermocouple for aircraft thermal environment tests, which can effectively block high temperatures, ensure accurate temperature measurement, and simultaneously have high temperature resistance and flexibility properties.

[0006] The technical solution of the present utility model is as follows:

[0007] A thermocouple for aircraft thermal environment tests is composed of a temperature measuring electrode, a magnetic insulation tube, a protective layer, and a high-temperature heat insulation layer arranged in parallel. The front end of the temperature measuring electrode is exposed, and the rear end of the temperature measuring electrode is wrapped with a magnetic insulation tube. The characteristic is that a protective layer is sleeved on the magnetic insulation tube, and a single-layer or multi-layer high-temperature heat insulation layer woven from quartz fiber is sleeved outside the protective layer.

[0008] When the high-temperature heat insulation layer is multi-layered, the high-temperature heat insulation layers are arranged at intervals.

[0009] The woven pattern of the high-temperature heat insulation layer is a plain weave structure.

[0010] The woven pattern of the high-temperature heat insulation layer is a basket weave structure.

[0011] An airfoil-shaped connector is sleeved at the end of the high-temperature heat insulation layer, and strip-shaped holes are respectively arranged at both ends of the airfoil-shaped connector.

[0012] The beneficial effect of the present utility model lies in:

[0013] The thermocouple for aircraft thermal environment tests can effectively block the transfer of heat through the high-temperature heat insulation layer. When the high-temperature heat insulation layer is single-layered, its high-temperature resistance can reach 1000 °C and it will not be damaged after lasting for more than 1 minute in this thermal environment; when the high-temperature heat insulation layer is double-layered, its high-temperature resistance can reach 1200 °C and it will not be damaged after lasting for more than 20 minutes in this thermal environment; the performance of the magnetic insulation tube can be effectively guaranteed through the high-temperature protective layer, enabling the temperature measuring electrode to measure temperature accurately, thereby ensuring the accuracy of the thermal environment of the test piece. Since the high-temperature heat insulation layer is obtained by weaving quartz fiber, it can effectively guarantee the flexibility of the high-temperature heat insulation layer, enabling it to be bent, so that the thermocouple can adapt to the surface layout of special-shaped test pieces, effectively improving the versatility of the thermocouple. It solves the problems of poor high-temperature resistance of existing thermocouples and the inability to combine high-temperature resistance and flexibility. Description of the Drawings

[0014] Figure 1 is a schematic structural diagram of the single-layer high-temperature heat insulation layer of the present utility model;

[0015] Figure 2 is a schematic structural diagram of the double-layer high-temperature heat insulation layer of the present utility model;

[0016] Figure 3 is an assembly schematic diagram of the airfoil-shaped connector of the present utility model;

[0017] Figure 4 It is the front view schematic diagram of the airfoil connecting piece of the present utility model;

[0018] Figure 5 It is the knitting schematic diagram of the high-temperature heat insulation layer of the present utility model.

[0019] In the figure: 1. Temperature measuring electrode, 2. Magnetic insulation tube, 3. Protective layer, 4. High-temperature heat insulation layer, 5. Airfoil connecting piece, 6. Strip-shaped hole. Specific implementation manner

[0020] The thermocouple for the thermal environment test of the aircraft is composed of a temperature-measuring electrode 1, a magnetic insulation tube 2, a protective layer 3, and a high-temperature heat insulation layer 4 arranged in parallel. The front end of the temperature-measuring electrode 1 is exposed to contact with the measured medium through the front end of the temperature-measuring electrode 1, so that a thermal electromotive force is generated under the action of the medium temperature. Thus, the temperature is measured by the voltage change generated by the electromotive force. The rear end of the temperature-measuring electrode 1 is wrapped with a magnetic insulation tube 2 to shield the external magnetic field through the magnetic insulation tube 2, thereby avoiding affecting the electromotive force of the temperature-measuring electrode 1 and ensuring accurate temperature measurement. A protective layer 3 is sleeved on the magnetic insulation tube 2 to improve the tensile strength of the thermocouple through the protective layer 3. A single-layer or multi-layer high-temperature heat insulation layer 4 woven from quartz fiber is sleeved outside the protective layer 3 to isolate the external high temperature through the high-temperature heat insulation layer 4, effectively block the heat transfer, avoid the high temperature from damaging the magnetic insulation tube 2 and the protective layer 3, ensure the magnetic shielding performance of the thermocouple at high temperature, and ensure accurate temperature measurement. When the high-temperature heat insulation layer is single-layer, its heat resistance can reach 1000 °C and it will not be damaged after lasting for more than 1 minute in this thermal environment; when the high-temperature heat insulation layer is double-layer, its heat resistance can reach 1200 °C and it will not be damaged after lasting for more than 20 minutes in this thermal environment. In order to meet the experimental needs, a multi-layer (3 layers or more) high-temperature heat insulation layer 4 is wrapped on the protective layer 3 to further improve the heat insulation ability and meet the requirements of the thermal environment assessment. Quartz glass fiber is a special glass fiber with a silica content of more than 99.90%. It has high heat resistance and can be used at temperatures below 1050 °C for a long time. It can withstand high temperatures up to 1700 °C instantaneously. The sleeve woven from quartz glass fiber yarn gives it good high-temperature resistance and excellent electrical insulation performance. In addition, the quartz fiber yarn has good flexibility. Since the high-temperature heat insulation layer 4 is woven from quartz fiber, the high-temperature heat insulation layer 4 woven from it retains its good bending performance. At the same time, the temperature-measuring electrode 1 also has bendable performance, making the thermocouple have excellent bendable operation performance. Furthermore, the thermocouple can be bent, enabling it to be set and temperature-measured on the surfaces of various flat test pieces and special-shaped test pieces. While ensuring the heat resistance performance, it can also ensure the flexibility, greatly enhancing its versatility. In addition, due to the flexibility of the thermocouple, it is convenient to store when not in use. It can be fixed and coiled into the form of a coil or a spool for storage, occupying little space, avoiding being mixed together, and being convenient to use; because it is coiled into a roll, during the use process, the operation space for personnel is large, and its layout can be moved according to the site layout situation, which is convenient for site arrangement and reduces unnecessary interference.

[0021] When the high-temperature heat insulation layer 4 is multi-layer, the high-temperature heat insulation layers 4 are arranged at intervals. For the double-layer or more than double-layer high-temperature heat insulation layers 4, a hollow layer is formed between layers, so that the layers do not contact each other, which can effectively reduce the heat conduction, thereby enhancing the heat insulation performance and effectively reducing the damage to the thermocouple in the thermal environment, and improving the heat resistance performance of the thermocouple in the thermal environment test.

[0022] The braided pattern of the high-temperature heat insulation layer 4 is a plain weave structure. The braided pattern of the high-temperature heat insulation layer 4 is a basket weave structure. The sleeve knitting machine weaves the quartz fiber yarn into a plain weave structure and a basket weave structure. The main differences between the braided patterns are as follows: compared with the basket weave structure, the weaving unit of the plain weave structure is smaller, the structure is more compact and firm, and the high-temperature heat insulation layer 4 formed on the outer layer of the thermocouple is denser and has better heat insulation performance; compared with the plain weave structure, the weaving unit of the basket weave structure is larger, the structure is relatively soft, and dense micro-pores are formed between the quartz fiber yarns, making the high-temperature heat insulation layer 4 woven by it have better heat insulation performance and better flexibility at the same time.

[0023] The end of the high-temperature heat insulation layer 4 is sleeved with a wing-shaped connector 5 to cement or bolt-fix the thermocouple to the test piece through the wing-shaped connector, thereby facilitating temperature measurement of the test point to be measured on the test piece. Bar-shaped holes 6 are respectively arranged at both ends of the wing-shaped connector 5 to facilitate cementing or bolt connection through the bar-shaped holes 6.

[0024] The high-temperature heat insulation layer 4 of the thermocouple for the thermal environment test of the aircraft is a quartz sleeve with a slightly larger diameter sleeved on the protective layer 3. However, in order to make the coating effect of the high-temperature heat insulation layer 4 more fitting and more convenient to use, a sleeve can also be directly woven on the protected layer 3, that is, a cored sleeve is woven with the protective layer 3, the magnetic insulation layer 2 and the temperature measuring electrode 1 as the inner core.

[0025] The tubular protective sleeve pre-woven according to the parameter requirements can be used by cutting the required length of the high-temperature heat insulation layer 4 of the corresponding model according to the on-site situation and sleeving it outside the protective layer 3 to form a coating layer during the thermal environment test. This method can be flexibly used according to the test needs, enhancing flexibility.

[0026] Or directly weave the high-temperature heat insulation layer 4 on the protective layer 3 through a sleeve knitting machine according to the actual use requirements, and weave the high-temperature heat insulation layer 4 into a cored sleeve, which can be directly taken for use during use; direct weaving can make its coating effect more fitting and more convenient to use, reducing the workload of personnel installation and thus improving the efficiency of the on-site thermal environment test.

[0027] The high-temperature heat insulation layer 4 is generally woven by a sleeve knitting machine. The sleeve knitting machine installs spindles on each lotus gear, passes the yarn of each spindle through the bunching ring and pulls it to the winding place. When running, the lotus gear drives the spindle to move in an "8" shape. The number of lotus gears is 1 / 2 of the total number of spindles of the equipment (for example: an existing 64-spindle knitting machine has 32 lotus gears). The yarn is divided into two paths, one path of yarn runs clockwise and the other path of yarn runs counterclockwise (see Figure 5, with the white yarn as one route and the black yarn as another route). Generally, the knitting structures include plain weave structure and basket weave structure: in the plain weave structure, one spindle participates in knitting on each lotus gear on average; in the basket weave structure, two spindles participate in knitting on each lotus gear on average. The casing knitting machine with basket weave structure can definitely achieve plain weave structure knitting. For example, when a 64-spindle casing knitting machine knits in basket weave structure, 64 spindles are needed, and when knitting in plain weave structure, 32 spindles are needed, and just leave half of the spindles empty evenly.

[0028] The casing knitting machine can produce products with different inner diameter ranges according to the different numbers of spindles. The minimum inner diameter of the casing is up to 0.3 mm. The number of configured strands of combined fiber filaments is calculated according to the diameter size to ensure that all combined fiber filaments can be closely and evenly arranged. The knitting process can adjust the knitting pitch by adjusting the lotus gear, and then adjust the tightness of the casing.

[0029] When knitting a cored casing for the high-temperature insulation layer 4, the inner core is placed in the central position (pulled from the bottom to the top and passed through the core barrel), and the yarn bundles are distributed around it. The yarns are tightly knitted around the inner core by adjusting the gears. When needed, knitting can be repeated and multiple layers can be coated. When repeating knitting, the knitting structure can also be changed according to the actual usage requirements to meet the needs.

[0030] For the protection casing knitting of a K-type thermocouple with an outer diameter of 1 - 2 mm, Method 1 is: using the protective layer 3, magnetic insulation layer 2, and temperature-measuring electrode 1 as the inner core, selecting quartz yarn below 72 tex and a casing knitting machine with an appropriate number of spindles, evenly spacing and using half of the spindles to knit in plain weave structure, adjusting the knitting gear to the minimum knitting pitch, so that the knitted yarns closely adhere to the outer surface of the material to be coated, forming the first high-temperature insulation layer 4. Using the knitted cored casing as the inner core, selecting quartz yarn below 95 tex and a casing knitting machine with an appropriate number of spindles, using all the spindles to knit in basket plain weave structure, forming the second high-temperature insulation layer 4. Using the knitted cored casing as the inner core, selecting quartz yarn below 133 tex and a casing knitting machine with an appropriate number of spindles, using all the spindles to knit in basket plain weave structure, forming the third high-temperature insulation layer 4.

[0031] The second method is: using the protective layer 3, the magnetic insulation layer 2 and the temperature measuring electrode 1 as the inner core, selecting quartz yarn below 72tex and a sleeve weaving machine with a suitable number of spindles, evenly spacing the upper half of the number of spindles to weave a plain weave structure, adjusting the weaving gear to the minimum weaving pitch, so that the yarn fits tightly on the surface of the coated material to form the first layer of high-temperature thermal insulation layer 4. Using the braided core sleeve as the inner core, selecting quartz yarn below 72tex and a sleeve weaving machine with a suitable number of spindles, evenly spacing the upper half of the number of spindles 1 / 1 to weave a plain weave structure, and slightly increasing the weaving gear on the basis to make the surface of the braided sleeve tight and smooth to form the second layer of high-temperature thermal insulation layer 4. Using the braided core sleeve as the inner core, selecting quartz yarn below 133tex and a sleeve weaving machine with a suitable number of spindles, and weaving a square plain weave structure with full spindles to form the third layer of high-temperature thermal insulation layer 4.

[0032] Both of the above methods can wrap three layers of quartz fiber yarn in the protective layer 3 so that the layers are tightly wrapped, thereby blocking the damage of the thermal environment to the thermocouple as much as possible.

[0033] The thermocouple used in the aircraft thermal environment test can effectively block the transfer of heat through the high-temperature insulation layer. When the high-temperature insulation layer is a single layer, its temperature resistance can reach 1000°C and last for more than 1 minute in this thermal environment without being damaged; when the high-temperature insulation layer is a double layer, its temperature resistance can reach 1200°C and last for more than 20 minutes in this thermal environment without being damaged; the high-temperature protective layer can effectively ensure the performance of the magnetic insulation tube, so that the temperature measurement electrode can measure the temperature accurately, thereby ensuring the accuracy of the thermal environment of the test piece. Since the high-temperature insulation layer is obtained by weaving quartz fiber, it can effectively ensure the flexibility of the high-temperature insulation layer, so that it can be bent, so that the thermocouple can adapt to the surface layout of special-shaped test pieces, effectively improving the versatility of the thermocouple. It solves the problem that the existing thermocouple has poor high-temperature resistance and cannot have both high-temperature resistance and flexibility.

Claims

1. A thermocouple for aircraft thermal environment testing, comprising a temperature measuring electrode (1), a magnetic insulating tube (2), a protective layer (3) and a high-temperature heat insulating layer (4) arranged in parallel, wherein the front end of the temperature measuring electrode (1) is exposed and the rear end of the temperature measuring electrode (1) is wrapped with the magnetic insulating tube (2), and characterized in that: A protective layer (3) is sleeved on the magnetic insulation tube (2), and a single-layer or multi-layer high-temperature heat insulation layer (4) woven from quartz fibers is sleeved on the outer side of the protective layer (3).

2. The thermocouple for aircraft thermal environment testing according to claim 1, characterized in that: When the high-temperature heat-insulating layer (4) is multiple layers, the high-temperature heat-insulating layers (4) are arranged at intervals.

3. The thermocouple for aircraft thermal environment testing according to claim 1, characterized in that: The woven pattern of the high-temperature heat insulation layer (4) is a plain weave structure.

4. The thermocouple for aircraft thermal environment testing according to claim 1, characterized in that: The woven pattern of the high-temperature heat insulation layer (4) is a basket weave structure.

5. The thermocouple for aircraft thermal environment testing according to claim 1, characterized in that: The high-temperature heat insulation layer (4) is provided with an airfoil connector (5) at its end, and strip holes (6) are provided at both end ends of the airfoil connector (5).

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