CN115307759A - Sleeve type standard thermocouple for noble metal electrode protection - Google Patents

Abstract

The invention provides a bushing type standard thermocouple for noble metal electrode protection, which comprises: the first electrode and the second electrode are in strip shapes and are consistent in length; the first ends of the first electrode and the second electrode are connected to be used as measuring ends, and the second ends of the first electrode and the second electrode are used as reference ends; the first electrode and the second electrode of the measuring end are respectively arranged in two tube cavities of the double-hole ceramic tube; the first electrode and the second electrode at the reference end are sequentially sleeved with at least one layer of insulating pipe and heat-shrinkable pipe and integrally wrapped in a stainless steel sleeve with a single side sealed; a first electrode and a second electrode between the measuring end and the reference end are respectively arranged in two tube cavities of the double-hole insulating tube; the opening end of the stainless steel sleeve is hermetically connected with the double-hole insulating tube through a sealing rubber ring; the double-hole ceramic tube is arranged in the quartz protective sleeve with a closed single side, and one side of the quartz protective sleeve close to the closed end is provided with a sand blasting and roughening area. The electrode and the environment are isolated, the electrode pollution is prevented, the uniformity of the standard thermocouple electrode is ensured, and the measurement precision is improved.

Description

Sleeve type standard thermocouple for noble metal electrode protection

Technical Field

The invention relates to the technical field of thermocouples, in particular to a sleeve type standard thermocouple for protecting a noble metal electrode.

Background

The thermocouple is a sensor for detecting temperature, and is widely applied to temperature measurement and monitoring in the industrial production process. Along with the development of temperature measurement technology, thermocouple temperature measurement field and suitable temperature bound have progressively got into more extreme environmental condition, and high accuracy measurement demand also obvious promotion, in order to adapt to this kind of actual demand, thermocouple structural design is becoming diversified day by day. At present, the structural design of a high-precision standard thermocouple in China adopts a wire exposed design, positive and negative electrode materials are respectively placed in a double-hole insulating ceramic tube, one end of the double-hole insulating ceramic tube is welded, and the other end of the double-hole insulating ceramic tube is connected with an electrical measuring device. The thermoelectric potential generated by the thermocouple comes from the whole thermocouple, so that the guarantee of the purity and the uniformity of the electrode are important preconditions influencing the measurement precision of the standard thermocouple, the maintenance of the long-term measurement accuracy and the use durability. In practical use, due to the exposed structural design of the standard thermocouple, quenching and shrinkage phenomena caused by electrode pollution frequently occur, so that the thermoelectric potential measurement value changes, and the measurement precision and accuracy of the thermocouple are seriously reduced; meanwhile, when the electrode is used in a bare state for a long time, irreversible damage occurs on the surface, and the electrode is reduced in diameter, broken and the like. Through a large amount of data analysis, the position where the electrode fracture occurs is usually the position where the pollutant is most seriously attached to the surface of the electrode.

In particular, in a standard measurement system, a standard thermocouple with a noble metal electrode with high purity is usually used for detection, and the corresponding noble metals are usually gold (Au), silver (Ag), and platinum group metals including ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), and platinum (Pt). In the traditional full-exposure measurement mode, the purity of noble metal on the surface of a standard thermocouple electrode is reduced due to the corrosion of environmental gas-liquid components. Meanwhile, the stress change of the standard thermocouple electrode can be caused by switching between different environmental temperatures in the measurement process, so that the surface of the standard thermocouple electrode is damaged, the uniformity of the standard thermocouple electrode is greatly influenced, the requirement on the detection precision is high under a standard measurement system, and the precision deviation can be caused by the change of the uniformity of the standard thermocouple electrode.

The demand and the usage of the high-precision noble metal thermocouple are increased year by year, and in a complex application scene, the consumption of platinum group metals and other noble metals is higher, so that high-precision noble metal raw materials are increasingly deficient, and further, the high-precision noble metal thermocouple is imported, and the production cost is greatly increased.

Therefore, a thermocouple for protecting the electrode from contamination while ensuring the measurement accuracy and precision of the standard thermocouple is needed.

Disclosure of Invention

In view of this, the embodiment of the present invention provides a bushing-type standard thermocouple for noble metal electrode protection, so as to eliminate or improve one or more defects existing in the prior art, and solve the problem that in different measurement environments, due to stress variation caused by environmental erosion and temperature environment variation, the uniformity of a standard thermocouple electrode varies, and thus the measurement accuracy and precision are reduced.

The technical scheme of the invention is as follows:

the invention provides a bushing type standard thermocouple for noble metal electrode protection, which at least comprises:

the device comprises a first electrode and a second electrode which are strip-shaped and have the same length, wherein the first electrode and the second electrode are conductors made of different materials; the first ends of the first electrode and the second electrode are connected to be used as measuring ends, the second ends of the first electrode and the second electrode are used as reference ends, and the second ends of the first electrode and the second electrode are respectively connected with a secondary instrument through leads to form a closed loop;

the first electrode and the second electrode of the measuring end are respectively arranged in two tube cavities of the double-hole ceramic tube; the first electrode and the second electrode of the reference end are sequentially sleeved with at least one layer of insulating pipe and one layer of heat-shrinkable pipe and integrally wrapped in a stainless steel sleeve with one side closed; the first electrode and the second electrode between the measuring end and the reference end are respectively arranged in two tube cavities of the double-hole insulating tube; the opening end of the stainless steel sleeve is hermetically connected with the double-hole insulating tube through a sealing rubber ring;

the double-hole ceramic tube is arranged in a quartz protective sleeve with a closed single side, and a sand blasting and roughening area is arranged on one side, close to the closed end, of the quartz protective sleeve.

In some embodiments, a handle is arranged at the joint of the double-hole ceramic tube and the double-hole insulating tube outside the first electrode and the second electrode, the handle comprises a handle main body and a handle rear cover, the handle main body is fixedly connected with the quartz protective sleeve and the double-hole ceramic tube, the handle rear cover is fixedly connected with the double-hole insulating tube, and the handle main body is movably connected with the handle rear cover.

In some embodiments, the handle rear cover is provided with an anti-bending spring and sleeved outside the double-hole insulating tube.

In some embodiments, the connection between the double-hole ceramic tube and the handle body is fixed by a polytetrafluoroethylene gasket to fill a gap.

In some embodiments, the handle is connected with the quartz protective sleeve through a locking cover and a locking sleeve.

In some embodiments, the double-hole ceramic tube and the double-hole insulating tube are connected, and the first electrode and the second electrode led out from the double-hole ceramic tube penetrate through the wire pressing core and are fixed through the wire pressing sheet; and an insulating sleeve is sleeved between the first and second electrodes and the wire pressing core.

In some embodiments, the stainless steel sleeve is connected with the double-hole insulating tube by using a locking bolt and a locking nut, and the sealing rubber ring is arranged between the locking bolt and the locking nut.

In some embodiments, the quartz protective sleeve is set to have a length of 700-800 mm and a thickness of less than 2 mm.

In some embodiments, the sand blasting roughening area is 20-30 mm away from one side (20-30) of the closed end of the quartz protective sleeve, the sand blasting depth of the sand blasting roughening area is less than 0.1 mm, and the sand blasting length is set to be (500-600) mm.

In some embodiments, the conductors are pure copper conductors arranged in a twisted pair with a splice pitch of (10-20) millimeters.

The invention has the beneficial effects that:

the invention provides a sleeve type standard thermocouple for noble metal electrode protection, which can avoid irreversible damage or fracture of the surface of a standard thermocouple electrode caused by the change of mechanical stress on the surfaces of a first electrode and a second electrode due to the change of temperature by respectively arranging the first electrode and the second electrode in a double-hole ceramic tube. Meanwhile, the quartz protective sleeve is sleeved outside the double-hole ceramic tube, so that the standard thermocouple electrode is prevented from being directly exposed in the external environment, and the electrode purity change of the standard thermocouple made of noble metal due to external environment corrosion and pollution is prevented. Therefore, the uniformity of the standard thermocouple electrode is not influenced by the environment, and the measurement precision, accuracy and durability of the standard thermocouple are improved. Furthermore, a sand blasting and roughening area is arranged on one side, close to the closed end, of the quartz protective sleeve, so that a light pipe effect of the quartz protective sleeve in thermocouple high-temperature measurement is effectively avoided, and the thermocouple and a measured object keep maximum heat balance during temperature measurement.

Furthermore, at least one layer of insulating tube is sleeved outside the first electrode and the second electrode, the insulating tube has certain hardness to protect the electrodes from bending easily while insulating, the influence of electrode stress on a thermocouple measurement result is further eliminated, and the measurement precision and accuracy of the thermocouple are ensured.

Furthermore, by controlling the length and the thickness of the quartz sleeve, the arrangement position of the sand blasting roughening area, the sand blasting depth and the length, the influence of uneven heat transfer caused by the absorptivity and the reflectivity of light radiation in the heat transfer process can be effectively reduced, and the measurement accuracy is ensured.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

It will be appreciated by those skilled in the art that the objects and advantages that can be achieved with the present invention are not limited to the specific details set forth above, and that these and other objects that can be achieved with the present invention will be more clearly understood from the detailed description that follows.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. For purposes of illustrating and describing some portions of the present invention, corresponding parts of the drawings may be exaggerated, i.e., may be larger, relative to other components in an exemplary apparatus actually manufactured according to the present invention. In the drawings:

fig. 1 is a schematic structural view of a bushing-type standard thermocouple for noble metal electrode protection according to an embodiment of the present invention.

Fig. 2 is a sectional view showing a structure of a bushing type standard thermocouple for noble metal electrode protection according to another embodiment of the present invention.

Fig. 3 is a general schematic diagram of a reference end structure of a bushing-type standard thermocouple for noble metal electrode protection according to an embodiment of the present invention.

Fig. 4 is a schematic diagram of a reference end package of a bushing-type standard thermocouple for noble metal electrode protection according to an embodiment of the present invention.

Fig. 5 is a sectional view showing a handle assembly structure of a bushing type standard thermocouple for noble metal electrode protection according to an embodiment of the present invention.

Description of reference numerals:

100: a measuring end; 200: a handle; 300: a reference terminal; 400: a first electrode;

500: a second electrode; 110: a double-hole ceramic tube; 120: a quartz protective sleeve; 121: sand blasting and roughening areas;

210: a handle body; 220: a handle rear cover; 240: pressing the wire core; 250: pressing line sheets;

260: an insulating sleeve; 270: a locking sleeve; 280: a locking cover; 310: a double-hole insulating tube;

320: a stainless steel sleeve; 330: sealing the rubber ring; 340: locking the bolt; 350: locking the nut;

360: a pure copper wire; 370: welding spots; 380: heat shrink tubing; 390: a polytetrafluoroethylene tube.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the following embodiments and accompanying drawings. The exemplary embodiments and descriptions of the present invention are provided to explain the present invention, but not to limit the present invention.

It should be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and/or processing steps closely related to the solution according to the present invention are shown in the drawings, and other details not so related to the present invention are omitted.

It should be emphasized that the term "comprises/comprising" when used herein, is taken to specify the presence of stated features, elements, steps or components, but does not preclude the presence or addition of one or more other features, elements, steps or components.

It is also noted herein that the term "coupled," if not specifically stated, may refer herein to not only a direct connection, but also an indirect connection in which an intermediate is present.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same reference numerals denote the same or similar parts, or the same or similar steps. Wherein like reference numerals refer to like elements throughout.

The working principle of the thermocouple is the Seebeck effect, a closed loop is formed by two material conductors with different components, when temperature difference exists between two ends, current is generated in the loop, and electromotive force-thermoelectric force exists between the two ends. The homogeneous conductors of the two different compositions are hot electrodes, the higher temperature end being the measurement end and the lower temperature end being the reference end, wherein the reference end is usually at some constant temperature. According to the functional relation between the thermoelectromotive force and the temperature, a thermocouple graduation table is manufactured; wherein the distribution table is obtained under the condition that the temperature of the reference end is 0 ℃, and different thermocouples have different distribution tables. When a third metal material is connected into the thermocouple loop, as long as the temperatures of two junctions of the material are ensured to be the same, the thermoelectric potential generated by the thermocouple is kept unchanged, namely, the third metal is connected into the loop to have no influence on the operation of the thermocouple. Therefore, when the thermocouple measures the temperature, the measuring instrument can be accessed to detect and obtain the thermoelectromotive force generated by the thermocouple, and the temperature of the measured medium can be calculated, wherein if the thermoelectromotive force and the measured temperature are in a certain proportional relation, the temperature of the reference end of the thermocouple is required to be kept unchanged when the thermocouple measures the temperature.

The detection precision requirements of thermocouples are different under different application systems, and accordingly, in order to meet the precision requirements under different detection systems, thermocouples made of different materials are generally adopted for processing. Under standard measurement systems, which generally require high accuracy for temperature monitoring, standard thermocouples commonly used in the art use gold (Au), silver (Ag), and platinum group metals including ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), and platinum (Pt) as standard thermocouple electrodes.

The standard thermocouple is used for keeping the uniformity of two electric heating poles in the application process, and the uniformity of the thermocouple refers to the uniformity degree of a thermocouple material. The thermode material of the thermocouple is uniform, and the thermoelectric potential of the thermocouple loop is related to the temperature at the cold and hot ends only, and not to the temperature distribution along the length of the thermode. If the thermode material is not uniform, the thermocouple loop will generate an additional thermoelectric force that will affect the overall thermoelectric force of the thermocouple loop. Therefore, the existence of uneven thermoelectric force can change the thermoelectric property of the thermocouple, and measurement error is generated, thereby reducing the accuracy of thermocouple temperature measurement. The two poles of the standard thermocouple can normally work only by keeping uniformity, and the accuracy of measurement can be ensured. Once the two poles of the standard thermocouple are not uniform, new additional thermoelectric force is generated, thereby affecting the measurement accuracy. The factors affecting the uniformity of a standard thermocouple mainly include two aspects of chemical factors and physical factors.

In a traditional measuring mode, a standard thermocouple electrode is usually directly exposed in an external environment, and a large amount of chemical raw materials with strong corrosivity cannot be applied in the standard thermocouple detection process; even in the chemical production process, a part of the metal is attached to the metal electrode of the standard thermocouple in a volatilized form and oxidized, thereby forming an impurity attachment layer. The external environment erosion causes the surface purity of standard thermocouple electrodes made of noble metals to change, which leads to non-uniformity. In addition, when the thermocouple directly contacts with the external environment, the mechanical stress of the standard thermocouple electrode is changed due to uneven stress or large temperature change in the using process, and uneven phenomena can also be caused, so that damage is caused. The surface uniformity of the standard thermocouple changes, which greatly affects the detection accuracy of the standard thermocouple. The present invention provides a bushing type standard thermocouple for noble metal electrode protection, as shown in fig. 1 and 2, comprising: a measuring end 100, a handpiece 200, a reference end 300, and a first electrode 400 and a second electrode 500.

The first electrode 400 and the second electrode 500 are long strips and are made of conductors made of different materials and have the same length; the first ends of the first electrode 400 and the second electrode 500 are connected as a measuring end 100, the second ends of the first electrode 400 and the second electrode 500 are connected as a reference end 300, and the second ends of the first electrode 400 and the second electrode 500 are respectively connected with a secondary instrument through leads to form a closed loop.

It should be noted here that the measurement terminal 100 and the reference terminal 300 are not independent structures with respect to the first electrode 400 and the second electrode 500, and it should be understood that the measurement terminal 100 and the reference terminal 300 are used to refer to a portion of the first electrode 400 and the second electrode 500 with respect to the whole, wherein the measurement terminal 100 is a portion of the first electrode 400 and the second electrode 500 where the length of the first terminal from the connection point is a first set value, and the measurement terminal 100 includes a portion of the first electrode 400 and a portion of the second electrode 500; the reference terminal 300 is a portion of the first electrode 400 and the second electrode 500 having a second end with a second predetermined length, and similarly, the reference terminal 300 includes a portion of the first electrode 400 and a portion of the second electrode 500.

The first electrode 400 and the second electrode 500 may be made of noble metals with high purity, such as gold electrodes and platinum electrodes, for example, the material index of the platinum electrode requires that the platinum-level resistance ratio is 1.3924, and since the thermoelectric force generated by the thermocouple is derived from the whole thermocouple, the purity and uniformity of the electrodes can be ensured by selecting the noble metals, and the measurement accuracy and precision of the thermocouple can be further improved. The reason that the lengths of the first electrode 400 and the second electrode 500 are required to be the same is that when the reference end 300 is packaged, the insertion depths of the two electrodes are the same and are as close as possible, so that the temperature sensing difference of the reference end caused by the length difference of the two electrodes is avoided, and the thermocouple measurement accuracy is not affected.

When the third metal material is connected into the thermocouple loop, as long as the temperatures of two junctions of the material are the same, the thermoelectric force generated by the thermocouple will remain unchanged, i.e. will not be influenced by the connection of the third metal into the loop. Therefore, the second ends of the first electrode 400 and the second electrode 500 are respectively welded with a lead, when the thermocouple measures temperature, the lead is connected to a measuring instrument to measure the thermoelectromotive force generated by the thermocouple, and the temperature of the measured medium can be calculated according to the proportional relation between the thermocouple and the temperature.

The lead is a pure copper lead cut from the same roll, and the diameter of the lead is usually 0.4-0.6 mm, so that the lead is convenient to mount and use. The single-core lead wire is convenient to thread and connect, but is not as flexible as a multi-core lead wire, and when more bending needs to be set, the multi-core lead wire is selected to be better. In this embodiment, the length of the pure copper wire is set to be 1.5 meters, the pure copper wire with the length of 3 meters is folded and cut into two wires with equal length, the two wires are mutually wound, the twisted pair is set, the twisting distance is 10-20 millimeters, the twisted pair has an anti-wave interference effect, and accurate signal transmission is realized during temperature measurement.

The first electrode 400 and the second electrode 500 of the measuring end 100 are respectively arranged in two cavities of the double-hole ceramic tube 110; the first electrode 400 and the second electrode 500 of the reference end 300 are sequentially sleeved with at least one layer of insulating tube and one layer of heat-shrinkable tube, and are integrally wrapped in the stainless steel sleeve 320 with one side closed; the first electrode 400 and the second electrode 500 between the measuring end 100 and the reference end 300 are respectively arranged in two cavities of the double-hole insulating tube 310; the open end of the stainless steel sleeve 320 is hermetically connected with the double-hole insulating tube 310 through a sealing rubber ring 330. The hardness of the double-hole ceramic tube 110 is high, the gold, silver and platinum group metal which are made into the standard thermocouple electrode are soft, and the mechanical stress change generated by external extrusion can be effectively prevented by protecting the standard thermocouple electrode through the double-hole ceramic tube 110, so that the uniformity change of the electrode is avoided.

As shown in fig. 3 and 4, the first electrode 400 and the second electrode 500 of the reference end 300 are respectively welded to the pure copper wire 360 by an electric iron, or can be connected by soldering, and the ptfe 390 and the heat shrinkable tube 380 are sequentially sleeved outside the first electrode 400 and the second electrode 500 of the reference end 300, wherein the ptfe 390 is made of an insulating material and has a certain hardness, and is sleeved outside the electrodes, so that the electrodes are not easily deformed, the electrode stress is greatly eliminated, and the ptfe 390 can fill the gaps in the tubes. The heat shrink tube 380 has a shielding layer and has a certain supporting force, and separates and insulates the positive electrode formed by the first electrode 400 and one pure copper wire and the negative electrode formed by the second electrode 500 and the other pure copper wire, so as to protect the welding point 370, and also insulate the stainless steel tube 320.

In one embodiment, the cold end of the reference terminal 300 adopts a gold electrode and a platinum electrode, and the cold end is cut flat to keep the length consistent. After two copper wires are welded by electric irons respectively, the two copper wires are insulated and fixed by a heat shrink tube. The wrapped reference end 300 is inserted into the bottom of the stainless steel sleeve 320 and the upper end of the stainless steel sleeve 320 is water tight. The thermocouple measuring wire is used for transmitting the thermoelectric potential output to thermoelectric potential measuring equipment connected with the measuring wire. The pure copper wire is required to be cut from the same roll, the purity is 99.99 percent, a single-core or multi-core wire can be used, and the diameter phi (0.4-0.6) mm of the wire is convenient to install and use. The length of the pure copper wire is usually 1.5m, the pure copper wire is folded by 3m and then cut into 1.5m with equal length, the two wires are twisted, and the hinge distance (10-20) mm is equal to the interval.

The double-hole ceramic tube 110 is arranged in a quartz protective sleeve 120 with one closed side, and a sand blasting and roughening area 121 is arranged on one side, close to the closed end, of the quartz protective sleeve 120.

Wherein, to the protecting sheathing, this embodiment designs and adopts high-purity quartz glass to make, and quartz glass possesses higher purity, is far more than the aluminium oxide material that daily protecting sheathing chooseed for use, and the highest use temperature can reach 1100 degrees centigrade, greatly increases thermocouple temperature measurement scope, consequently no matter from application temperature range, or heat-conduction ability and heat balance effect, chooses for use quartz protective case to be the satisfying standard thermocouple service condition most, has guaranteed the precision and the degree of accuracy of temperature measurement.

Specifically, the protective quartz sleeve 120 is required to be processed by using 99.9% high-purity silicon oxide gas refining, and can endure a temperature of 1000 ℃ for a long time. The appearance is transparent, the pipe is straight, the wall thickness is uniform, and no bubble, gas line and devitrification phenomenon exist in visual inspection. One end of the pipe is sealed, and the wall thickness of the sealed end is uniform. The other end of the tube is subjected to a port burning treatment. Typically the wall thickness is 1mm. The quartz protective sleeve 120 can effectively isolate the standard thermocouple electrode from the external environment, and prevent the corrosion of other substances in the environment.

The surface of the quartz protective sleeve 120 is contaminated with oil and reacts with silicon oxide at high temperature to cause a crystallization phenomenon, so that in order to ensure the thermocouple manufacturing process, hands are not used to directly touch the quartz tube, cotton gloves can be worn when the hands are required to contact the quartz tube, and if the hands are not carefully contacted with the quartz tube, the contact part is carefully and timely wiped with alcohol to remove the contaminated oil and dirt.

When a standard thermocouple electrode is protected by providing the quartz protective sleeve 120, a decrease in heat transfer efficiency is inevitable. However, in the application scenario of a standard thermocouple, there is no requirement for the detection speed, so that it is only necessary to ensure that the protective quartz sleeve 120 can effectively receive the heat source form in the environment.

Specifically, there are three basic heat transfer modes, namely heat conduction, heat radiation and heat convection, and in order to keep the thermocouple in maximum thermal balance with the measured object during measurement, the embodiment is directed to the heat radiation heat transfer mode, and a sandblasting roughening area 121 is arranged on one side of the quartz protective sleeve 120 close to the closed end. The quartz protective sleeve 120 has a smooth surface, and the absorption capacity of the spectrum is enhanced after sand blasting and roughening, so that the heat exchange capacity is enhanced, and the light pipe effect of the quartz protective sleeve 120 in thermocouple high-temperature measurement is avoided.

In this embodiment, a large number of experiments verify that the length of the quartz protective sleeve 120 is 750 mm, the thickness of the sleeve wall is 1mm, the distance between the sandblasting roughening area 121 and the closed end side of the quartz protective sleeve 120 is 20-30 mm, the sandblasting depth of the sandblasting roughening area 121 is less than 0.1 mm, and the sandblasting length is set to 550 mm.

In this embodiment, the handle 200 is disposed at the connection between the two-hole ceramic tube 110 and the two-hole insulating tube 310 outside the first electrode 400 and the second electrode 500, the handle 200 includes a handle main body 210 and a handle rear cover 220, the handle main body 210 is fixedly connected to the quartz protective sleeve 120 and the two-hole ceramic tube 110, the handle rear cover 220 is fixedly connected to the two-hole insulating tube 310, and the handle main body 210 is movably connected to the handle rear cover 220. The handle 200 mainly functions as a positioning assembly of the thermode, the inner double-hole alumina tube and the outer quartz protection tube.

As shown in fig. 5, the handle body 210 is connected to the quartz protective sleeve 120 through the locking cover 280 and the locking sleeve 270, the locking sleeve 270 is an elastic metal locking sleeve, i.e., a long opening is formed at one end of the metal circular tube and sleeved outside the quartz protective sleeve 120, the locking cover 280 is used for compressing the locking sleeve 270, so that the locking sleeve 270 can be integrally, uniformly and radially contracted when being pressed, the quartz protective sleeve 120 is clasped and fixed, and the locking cover 280 is provided with threads and is rotationally fixed with the handle body 210.

The length of the double-hole ceramic tube 110 at the side close to the handle 200 is longer than that of the quartz protective sleeve 120, so that the double-hole ceramic tube 110 needs to be separately fixed in the handle body 210. The ptfe gasket 230 is sleeved on the double-hole ceramic tube 110, the gap between the double-hole ceramic tube 110 and the handle body 210 is filled with the ptfe gasket 230 to fix the double-hole ceramic tube, and the ptfe gasket 230 is made of an insulating material to insulate the double-hole ceramic tube.

In this embodiment, after the double-hole ceramic tube 110 is fixed to the handle body 210, the first electrode 400 and the second electrode 500 are respectively led out from two lumens of the double-hole ceramic tube 110, the first electrode 400 and the second electrode 500 respectively penetrate through the wire pressing core 240, and the two electrodes are fixedly pressed at the left end and the right end of the wire pressing core 240 by the wire pressing sheet 250, so that the electrodes are not easy to move, and the positions of the elements of the measuring end 100 and the reference end 300 are further fixed.

Wherein, the insulation sleeve 260 is sleeved between the led first electrode 400 and the second electrode 500 and the wire pressing core 240. The wire core 240 for fixing the electrodes is also made of an insulating material. The first electrode 400 and the second electrode 500 fixed by the wire pressing core 240 and the wire pressing sheet 250 are placed in two lumens of the double-hole insulating tube 310 and extend to the reference end 300.

In the present embodiment, the double-hole insulating tube 310 is made of a soft material, and the polytetrafluoroethylene tube 390 is sleeved outside the first electrode 400 and the second electrode 500 in the double-hole insulating tube 310 to fill the gap and insulate.

In this embodiment, the handle rear cover 220 is provided with an anti-bending spring 240, and is sleeved outside the dual-hole insulating tube 310. The anti-bending spring 240 has a length of about one palm width, and prevents the first electrode 400 and the second electrode 500 from being bent, broken or displaced when the handle 200 is held by a hand, thereby ensuring stability of the internal structure of the thermocouple.

In this embodiment, the stainless steel sleeve 320 is connected to the double-hole insulating tube 310 by using the locking bolt 340 and the locking nut 350, and the sealing rubber ring 330 is disposed between the locking bolt 340 and the locking nut 350.

In this embodiment, the assembly correctness of the bushing-type standard thermocouple for noble metal electrode protection can be quickly checked after the assembly is completed. Firstly, measuring the resistance at two ends of a pure copper wire by using a universal meter, checking whether the pure copper wire is conducted or not, if the pure copper wire is not conducted, welding two electrodes at a thermocouple measuring end or welding a copper wire at a reference end has problems, if the pure copper wire is conducted, carrying out next detection, putting a golden platinum thermocouple reference end packaging part into an ice point, placing a hot end in a room temperature environment, measuring thermoelectromotive force by using a digital nano volt, and if the thermoelectromotive force is within a range of 0.128-0.184 millivolt, basically enabling a thermocouple assembly structure to be normal, and marking the anode and the cathode of the pure copper wire.

Wherein, the thermocouple measuring end and the reference end are both put into the freezing point, and are kept stand for 25 minutes, and the output thermal electromotive force is measured by a digital nano-volt meter. The mean value is read over 3 minutes and the thermoelectromotive force should be in the range of + -5 μ V.

In summary, the present invention provides a bushing-type standard thermocouple for noble metal electrode protection, in which a first electrode and a second electrode are respectively disposed in a two-hole ceramic tube, so as to avoid irreversible damage or fracture of the surface of the standard thermocouple electrode caused by the change of mechanical stress on the surfaces of the first electrode and the second electrode due to temperature change. Meanwhile, the quartz protective sleeve is sleeved outside the double-hole ceramic tube, so that the standard thermocouple electrode is prevented from being directly exposed in the external environment, and the electrode purity change of the standard thermocouple made of noble metal due to external environment corrosion and pollution is prevented. Therefore, the uniformity of the standard thermocouple electrode is not influenced by the environment, and the measurement precision, accuracy and durability of the standard thermocouple are improved. Furthermore, a sand blasting and roughening area is arranged on one side, close to the closed end, of the quartz protective sleeve, so that a light pipe effect of the quartz protective sleeve in thermocouple high-temperature measurement is effectively avoided, and the thermocouple keeps maximum thermal balance with a measured object during temperature measurement.

Furthermore, at least one layer of insulating tube is sleeved outside the first electrode and the second electrode, the insulating tube has certain hardness to protect the electrodes from bending easily while insulating, the influence of electrode stress on a thermocouple measurement result is further eliminated, and the measurement precision and accuracy of the thermocouple are ensured.

Furthermore, by controlling the length and the thickness of the quartz sleeve, the arrangement position of the sand blasting roughening area, the sand blasting depth and the length, the influence of uneven heat transfer caused by the absorptivity and the reflectivity of light radiation in the heat transfer process can be effectively reduced, and the detection precision is ensured.

Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments in the present invention.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes may be made to the embodiment of the present invention by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A telescopic standard thermocouple for noble metal electrode protection, characterized by comprising at least:

the device comprises a first electrode and a second electrode which are long and consistent in length, wherein the first electrode and the second electrode are conductors made of different materials; the first ends of the first electrode and the second electrode are connected to be used as measuring ends, the second ends of the first electrode and the second electrode are used as reference ends, and the second ends of the first electrode and the second electrode are respectively connected with a secondary instrument through leads to form a closed loop;

the first electrode and the second electrode of the measuring end are respectively arranged in two tube cavities of the double-hole ceramic tube; the first electrode and the second electrode of the reference end are sequentially sleeved with at least one layer of insulating pipe and one layer of heat-shrinkable pipe, and are integrally wrapped in a stainless steel sleeve with a single side sealed; the first electrode and the second electrode between the measuring end and the reference end are respectively arranged in two tube cavities of the double-hole insulating tube; the opening end of the stainless steel sleeve is hermetically connected with the double-hole insulating tube through a sealing rubber ring;

the double-hole ceramic tube is arranged in a quartz protective sleeve with a closed single side, and a sand blasting and roughening area is arranged on one side, close to the closed end, of the quartz protective sleeve.

2. The telescopic standard thermocouple for noble metal electrode protection according to claim 1, wherein a handle is disposed at a junction of the two-hole ceramic tube and the two-hole insulating tube outside the first electrode and the second electrode, the handle comprises a handle body and a handle rear cover, the handle body is fixedly connected with the quartz protective sleeve and the two-hole ceramic tube, the handle rear cover is fixedly connected with the two-hole insulating tube, and the handle body is movably connected with the handle rear cover.

3. The bushing type standard thermocouple for noble metal electrode protection according to claim 2, wherein an anti-bending spring is provided at the handle rear cover and sleeved outside the double-hole insulating tube.

4. The bushing-type standard thermocouple for noble metal electrode protection according to claim 1, wherein a gap is filled and fixed at a junction of the ceramic bushing and the handle body by a teflon spacer.

5. The telescopic standard thermocouple for noble metal electrode protection according to claim 1, wherein the handle is fixedly connected to the quartz protective sleeve by a locking cap and a locking sleeve.

6. The bushing type standard thermocouple for noble metal electrode protection according to claim 1, wherein the first electrode and the second electrode led out from the double-hole ceramic tube pass through a wire pressing core and are fixed by a wire pressing sheet between the double-hole ceramic tube and the double-hole insulating tube; and an insulating sleeve is sleeved between the first and second electrodes and the wire pressing core.

7. The bushing type standard thermocouple for noble metal electrode protection according to claim 1, wherein the stainless steel bushing is connected with the double-hole insulating tube by a locking bolt and a locking nut, and the sealing rubber ring is arranged between the locking bolt and the locking nut.

8. The bushing-type standard thermocouple for noble metal electrode protection according to claim 1, wherein the length of the quartz protective bushing is set to 700-800 mm, and the thickness of the bushing is less than 2 mm.

9. The telescopic standard thermocouple for noble metal electrode protection according to claim 1, wherein the sandblasting roughening region is 20 to 30 mm from the side of the closed end of the quartz protective sleeve, the sandblasting depth of the sandblasting roughening region is less than 0.1 mm, and the sandblasting length is set to 500 to 600 mm.

10. The bushing-type standard thermocouple for noble metal electrode protection according to claim 1, wherein said wire is a pure copper wire, said pure copper wire is provided in a twisted pair, and a pitch of the twist is 10-20 mm.

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