KR102449907B1 - A manufacturing method of temperature sensor using measure of exhaust gas - Google Patents

Abstract

The temperature sensor for automobile exhaust gas measurement manufactured by the manufacturing method according to the present invention has a temperature element joined to one end of an insulated cable, but oxygen supplied from the other end of the cable is not lost by oxidizing the core wire to which the temperature element is bonded at a high temperature. By ensuring that the temperature element is sufficiently supplied, the accuracy can be improved even at a high temperature of around 1,000℃ without causing defects such as corrosion, thermal deformation, and element change.

Description

A manufacturing method of temperature sensor using measure of exhaust gas

The present invention relates to a method for manufacturing a temperature sensor for measuring vehicle exhaust gas, and more particularly, a temperature element is bonded to one end of an insulated cable, and oxygen supplied from the other end of the cable by oxidizing a core wire to which the temperature element is bonded at a high temperature The present invention relates to a method for manufacturing a temperature sensor for measuring vehicle exhaust gas, which has improved stability at high temperatures by sufficiently supplying it to a temperature element without loss.

Since the implementation of the European Union's exhaust gas regulation (EURO 1) in 1992, diesel vehicle exhaust gas regulation has been in progress worldwide in accordance with the conditions of each country. With the strengthening of these regulations, the development of reduction devices by parts and system makers and the demand from automobile manufacturers are increasing. In particular, the demand for exhaust gas temperature sensors for precise exhaust gas control and exhaust gas reduction monitoring is increasing.

On the other hand, a temperature sensor is a sensor that responds to changes in temperature and is used in various industrial sites for automatic temperature management. In addition, the temperature sensor used in automobiles is roughly used for engine coolant temperature detection, fuel temperature detection, intake air temperature detection, and exhaust gas temperature detection.

Among them, the temperature sensor used to measure the temperature of exhaust gas varies depending on the material of the device, but has an operating range of -50 to 1,100°C, and is installed in HP-EGR (High Pressure Exhaust Gas Recirculation) to measure the temperature of the circulating exhaust gas. It measures and transmits a signal for opening and closing the EGR valve, or when the exhaust gas temperature rises above a certain temperature, it is provided to the ECU (Engine Control Unit) to deliver the PM (Particulate Matter) regeneration temperature.

Such a temperature sensor generally includes a temperature element and a mineral insulated cable (M.I cable) connected to the temperature element. If you look at the bonding state of the temperature element and the mineral insulated cable, a pair of electrode wires extending from the temperature element are joined to the wiring located at the end of the mineral insulated cable.

And the electrical signal generated by the temperature element is transmitted through the mineral insulated cable, and the corresponding electrical signal is transmitted to the lead wire connected to another end of the mineral insulated cable, and then to the MCU in the vehicle through the connector connected to the lead wire. . And, when bonding the electrode wire of the temperature element and the wiring of the mineral insulated cable, in general, the electrode wire and the wire are buttted together and then joined by laser welding.

The temperature sensor is largely divided into a contact type and a non-contact type. The contact type is a method of directly contacting the sensor to a detection object to detect the temperature, and the non-contact type is a method of measuring radiant heat emitted to the detection object.

However, high environmental resistance and high reliability of temperature sensors are required for temperature sensors used in automobiles because they operate in the special environment of automobiles and are linked to the safety of occupants. Therefore, the temperature element used for the above-described temperature detection of the exhaust gas of a vehicle generally uses a non-contact type rather than a contact type for the above-mentioned environmental resistance and reliability.

In particular, the contact type has the advantage of fast response speed because it is directly exposed to exhaust gas, but the temperature element is polluted by the exhaust gas pollutants, and as time passes, the response characteristics deteriorate and reliability is lowered. On the other hand, since the non-contact type does not directly contact the exhaust gas, contamination of the temperature element like the contact type does not occur, which is advantageous for reliability.

In the case of a non-contact temperature element, the temperature element and the electrode wire are protected by being built into a sealed tube. In addition, a filler is filled in an empty space such as a tube having a built-in temperature element to fix and protect the internal temperature element and the electrode wire.

However, in the case of a non-contact temperature element embedded in a tube, etc., there is a problem in the manufacturing process that it is difficult to accurately position and assemble the temperature element inside the tube, etc., because the cross-sectional area of the tube in which the temperature element is installed is small and the length is long. In addition, if the oxygen supply to the temperature element is insufficient, the resistance to impurities is rapidly reduced due to devitrification at high temperature or even the insulating layer of the temperature element is destroyed, which may affect the platinum pattern of the element, eventually This point also causes difficulties in the manufacturing process because defects may occur due to variations in resistance values due to pattern damage.

In the case of temperature sensors, due to their characteristics, they are exposed to high temperatures and vibrations close to 1,000°C, and at the same time, they must respond quickly to temperature changes while securing weather resistance, durability, mechanical stability and reliability against chemical attack by high-temperature exhaust gases. , it is difficult to manufacture a temperature sensor that satisfies all of the above characteristics due to the characteristics of its structure.

Republic of Korea Patent Publication No. 10-2008-0102510 (November 26, 2008)

The present invention has been devised to solve the above-described problem, wherein a temperature element is bonded to one end of an insulated cable, and by oxidizing the core wire to which the temperature element is bonded at a high temperature, oxygen supplied from the other end of the cable to the temperature element without loss An object of the present invention is to provide a method for manufacturing a temperature sensor for measuring automobile exhaust gas, which is sufficiently supplied to increase stability at high temperatures.

The present invention relates to a method of manufacturing a temperature sensor for measuring vehicle exhaust gas.

One aspect of the present invention is

a) preparing a mineral insulated cable including a wiring, an insulator, and a protective tube;

b) bonding the wiring and the temperature element;

c) joining the tube to the protective tube so as to block the temperature element from the outside;

d) oxidation treatment by heating the portion to which the protective tube is joined among both ends of the mineral insulated cable at a temperature of 900 to 1,000° C. for 8 to 20 hours; and

e) filling the inside of the tube with a filler and sealing the tube;

It relates to a method of manufacturing a temperature sensor for measuring vehicle exhaust gas comprising a.

In the present invention, step d) is

d1) putting the tube into a heating furnace and heating the tube for 30 to 60 minutes while raising the temperature from room temperature to 950 to 1,000°C;

d2) leaving the tube for 480 to 1,200 minutes while maintaining the heating furnace at a temperature of 1,000° C. or less; and

d3) lowering the temperature to 200° C. by cooling the heating furnace by natural cooling in the heating furnace;

It is characterized in that it includes.

In addition, the step d) is characterized in that it proceeds under an atmospheric atmosphere, more specifically, under an oxygen atmosphere.

In addition, the wiring, metal tube and tube, aluminum, carbon, chromium, copper, iron, manganese, nickel, sulfur, silicon, nitrogen, zirconium, molybdenum, titanium, niobium and phosphorus comprising two or more materials selected from do.

In addition, the filler is characterized in that any one or a plurality selected from magnesium oxide, zinc oxide, boron nitride, aluminum oxide, zirconium oxide, aluminum nitride, silicon nitride and cement.

The temperature sensor for automobile exhaust gas measurement manufactured by the manufacturing method according to the present invention has a temperature element joined to one end of an insulated cable, but oxygen supplied from the other end of the cable is not lost by oxidizing the core wire to which the temperature element is bonded at a high temperature. By ensuring that the temperature element is sufficiently supplied, the accuracy can be improved even at a high temperature of around 1,000℃ without causing defects such as corrosion, thermal deformation, and element change.

1 is an exploded perspective view of a temperature sensor for measuring vehicle exhaust gas according to the present invention.
2 is a cross-sectional view showing a cap, a tube and a temperature element according to the present invention.
3 is a cross-sectional view showing a temperature element according to the present invention and a mineral insulated cable are combined.
4 shows a cross-section of a flange according to the present invention.
5 illustrates an oxidation treatment process according to an embodiment of the present invention.

Hereinafter, a method of manufacturing a temperature sensor for measuring vehicle exhaust gas according to the present invention will be described in more detail by way of Examples and Comparative Examples. However, the embodiments introduced below are provided as examples so that the spirit of the present invention can be sufficiently conveyed to those skilled in the art.

Therefore, the present invention is not limited to the embodiments presented below and may be embodied in other forms, and the embodiments presented below are only described to clarify the spirit of the present invention, and the present invention is not limited thereto.

At this time, unless there are other definitions in the technical terms and scientific terms used, it has the meaning commonly understood by those of ordinary skill in the technical field to which this invention belongs, and in the following description, it may unnecessarily obscure the subject matter of the present invention. Descriptions of possible known functions and configurations will be omitted.

Also, the singular forms used in the specification and appended claims may also be intended to include the plural forms unless the context specifically dictates otherwise.

In addition, the drawings introduced below are provided as examples so that the spirit of the present invention can be sufficiently conveyed to those skilled in the art. Therefore, the present invention is not limited to the drawings presented below and may be embodied in other forms, and the drawings presented below may be exaggerated to clarify the spirit of the present invention. Also, like reference numerals refer to like elements throughout.

Also, the singular forms used in the specification and appended claims may also be intended to include the plural forms unless the context specifically dictates otherwise.

In describing the components of the present invention, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only for distinguishing the elements from other elements, and the essence, order, or order of the elements are not limited by the terms. When it is described that a component is “connected”, “coupled” or “connected” to another component, the component may be directly connected or connected to the other component, but another component is between each component. It should be understood that elements may be “connected,” “coupled,” or “connected.”

The temperature sensor for measuring vehicle exhaust gas according to the present invention has a temperature element inside as shown in FIG. 1, specifically, a cap 110, a tube 120, a temperature element 130, a flange 140, and a mineral insulation cable ( 150) may be included.

First, the temperature sensor for measuring vehicle exhaust gas of the present invention has a long circular rod shape as a whole, a cap 110 inserted into the tube 120 from the top, wraps and protects the temperature element inside, and protects the mineral insulation cable. A tube 120 that is fitted and coupled to the upper end, a temperature element 130 positioned in the tube and joined to the wiring of the mineral insulated cable, and a wiring 151 at the upper end are exposed and joined to the temperature element at the same time as the tube and It has a structure in which a mineral insulation cable 150 that is coupled to protect the temperature element and a flange fitted to a portion of an outer surface of the mineral insulation cable are coupled. In addition, the inside of the tube is filled with a filler, and the insulating material is filled in a layer 154 inside the mineral insulated cable.

The cap 110 performs a function of sealing the tube by inserting, bonding, and bonding to the upper end of the tube after the process of filling the inside of the tube with the filler.

At this time, the cap has a circular plate shape having a certain thickness as shown in FIG. 2, is a structure coupled to the upper end of the tube 120 to seal the inside of the tube, the central body of the cap body 111, the cap body It may include an indentation portion 112 recessed in a circle at the center of the upper surface and a protruding end 113 protruding in a circle at the lower surface of the cap body.

The cap body has a diameter that matches the diameter of the tube 120 so that the lower surface of the cap body 111 is in contact with the top surface of the tube 120 when the cap 110 is combined with the tube 120 . .

In addition, the protruding end 113 may have a diameter that matches the inner diameter of the tube 120 . So, when the cap 110 is coupled to the tube 120 , the outer circumferential surface of the protruding end 113 comes into contact with the inner circumferential surface of the tube 120 . Therefore, when the cap 110 is inserted into the tube 120, the center is immediately aligned by the protruding end 113, so there is no need to align the center in order to combine the cap 110 with the tube 120 separately. The faster the process, the higher the manufacturing efficiency.

In addition, since the protruding end 113 has a structure protruding to a predetermined height from the lower surface of the cap body as described above, when the cap 110 is coupled to the tube 120, the filler filled in the tube is disposed at the protruding end ( 113), since it is combined while being pressed by the protruding surface, it is possible to eliminate microbubbles that may be formed in the filler and increase the measurement rate of the temperature sensor.

The tube 120 has a cylindrical shape with both ends open, but has a dual structure of upper and lower portions, and the lower end is coupled to one end of the protective tube 152 of the mineral insulated cable 150 to accommodate the temperature element 140 therein. As a structure that enables it, it may be configured to include a tube upper end 121, a stepped 122, a tube lower end 123, and a tube welded portion 124 as shown in FIG.

The tube upper end 121 is formed such that the outer diameter is less than or equal to the diameter of the protective tube 162 and the inner diameter coincides with the width of the temperature element 130 or is greater than or equal to a certain size. Here, since the portion coupled with the mineral insulated cable 150 becomes the tube lower end 123, the tube upper 121 is irrespective of the diameter size of the mineral insulated cable 150, and the interval with the temperature element 130 located inside is minimized. to have an inner diameter that can be

The tube lower end 123 is formed so that the inner diameter coincides with the outer diameter of the protective tube 152 of the mineral insulated cable 150 is covered and coupled to the upper end of the protective tube 152 . Therefore, unlike the conventional one, when assembling the tube 120 with the mineral insulated cable 150, even if the center is not separately adjusted, if the lower part of the tube is immediately put on the mineral insulated cable, the center is aligned. one effect.

The step 122 is a coupling portion between the tube upper end 121 and the tube lower end 123, and refers to a jaw formed because the cross-sectional area of the tube upper end 121 is smaller than the cross-sectional area of the tube lower end 123, and the protective tube (152) is inserted into the tube lower end 123 and when coupled, the longitudinal cross-section of the protective tube 152 and the inner surface of the stepped 122 abut and are caught by the stepped 122 so as to be fixed. Therefore, unlike the prior art, there is no need to adjust the length at which the tube 120 is inserted into the protective tube 152 of the mineral insulated cable 150 during the assembly process of the temperature sensor, thereby facilitating the assembly process.

The weld tube 124 is a portion facing the surface of the protective tube 152 of the mineral insulated cable 150 among the ends of the tube lower end 123, and after assembling the tube 120 to the mineral insulated cable 150 The end of the tube lower end 123 and the protective tube 152 are joined by welding or an adhesive.

The cap and tube are not limited in material, but include two or more materials selected from aluminum, carbon, chromium, copper, iron, manganese, nickel, sulfur, silicon, nitrogen, zirconium, molybdenum, titanium, niobium and phosphorus It is preferably an alloy.

Specifically, the cap and tube may include 61 to 62% by weight of nickel, 22 to 23% by weight of chromium, 1 to 2% by weight of aluminum, 0.01 to 0.1% by weight of carbon, 0.1 to 0.5% by weight of manganese, 0.1 to 0.5% by weight of silicon, and iron It is preferably formed of an alloy having a composition of 13 to 15% by weight.

The composition is a heat-resistant alloy mainly made of nickel, has good heat resistance, is not oxidized in an oxidizing air stream of 900 ° C. or higher, and is therefore suitable as a material for the outer skin of a sensor that must withstand high temperatures, is not immersed in exhaust gas containing sulfur, and is It has excellent mechanical properties such as elongation, tensile strength, and yield point, and is preferable because of its high corrosion resistance.

As shown in FIG. 2, the temperature element 130 is bonded to the wire exposed at one end of the mineral insulation cable to sense the temperature, and the temperature element may further include a pair of electrode wires 131 joined to the wire. can

In general, various types of temperature sensor elements may be used as the temperature element. For example, the temperature element may use a platinum resistance temperature sensor such as HDZ420 (Heraeus).

Of course, this is only an example, and the temperature element 130 may be replaced with various types of temperature sensor elements having similar characteristics and materials, such as a thermistor or a thermocouple thermocouple.

In the case of the platinum resistance temperature sensor, a phenomenon in which the electrical resistance of a metal conductor changes according to a change in temperature is utilized. It has the advantage of high stability and high-precision measurement.

The electrode line 131 is a pair of metal wires extending from the temperature element, and after overlapping with the wiring 151 of the MI cable 150, the overlapped portion may be joined by arc welding or laser welding.

The electrode wire is not limited in material, for example, may be any one or a plurality selected from platinum, nickel and copper, and it is most preferable to use platinum among them.

The flange 140 has a cylindrical shape with both ends open so that the mineral insulation cable 150 is penetrated and coupled. After the mineral insulation cable 150 is inserted into the exhaust gas pipe of a vehicle, it performs a function of sealing the connection part of the exhaust gas pipe.

Specifically, the flange 140 is configured to include a flange upper end 141 whose outer circumferential surface is extended and extended as shown in FIG. 4 and a flange lower end 142 that is less than or equal to the diameter of the flange upper end 141, so that the flange upper end 141 and The flange lower end 142 may be connected to form a jaw.

Therefore, after the temperature sensor according to the present invention is assembled in the actual exhaust gas system, the outer peripheral surface is expanded and extended so that the flange upper end 141 with a large cross-sectional area seals the end of the exhaust gas pipe, so that the The joint of the temperature sensor remains stable and allows the exhaust gas to be sealed without leaking.

The flange is also not limited in material, and for example, stainless (austenite, martensite, ferrite, etc.) or other ferrous or non-ferrous metals can be used. good to do Since the austenitic stainless steel contains chromium and nickel, it has excellent corrosion resistance to salt or acid. Of course, the material of the flange 150 is not limited to the free-cut stainless steel (ST303), and it will be natural that various types of materials having similar characteristics may be used.

The mineral insulation cable is a long rod-shaped structure, and as shown in FIG. 3 , a wiring 151 protruding from one end and connected to the electrode wire 131, and a lead wire protruding from the other end to be connected to another device. 153 and a protective tube 152 having a cylindrical shape surrounding the wiring 151 and having an insulator layer 154 formed therein.

The wiring 151 is provided in the center of the mineral insulated cable, and one end is exposed at the top of the mineral insulated cable, and may be overlapped with the electrode wire of the temperature element and then joined to each other by welding or the like.

The protective tube 152 has a cylindrical shape with both ends open, and a wiring and an insulator layer 154 may be accommodated therein. In addition, as described above, the tube lower end 123 is covered on one end of the protective tube and a part overlaps with each other and is coupled, so that the center of the tube is directly covered by the mineral insulation cable without separately adjusting the center of the mineral insulation cable and the tube. As it can be matched, the assembly precision is high, and assembly is quick and easy.

The lead wire 153 refers to a wire having a shape formed so as to be provided at the lower end of the protective tube 152 as an extension wire with a stripped end of the coating and to be connected to another device to which the temperature sensor is to be mounted. In an embodiment of the present invention, the connection method of the end of the MI cable 150 is exemplified using the lead wire 153, but in addition, various connections that perform similar functions such as connection fittings, connectors, terminal blocks, etc. It would be obvious that the method could be used.

The wiring and protective tube of the mineral insulated cable are also not limited in material, but like the cap and tube, aluminum, carbon, chromium, copper, iron, manganese, nickel, sulfur, silicon, nitrogen, zirconium, molybdenum, titanium, niobium and Preferably, two or more materials selected from phosphorus are included, and more preferably, similarly to the cap and tube, 61 to 62% by weight of nickel, 22 to 23% by weight of chromium, 1 to 2% by weight of aluminum, 0.01 to 0.1% by weight of carbon %, manganese 0.1 to 0.5% by weight, silicon 0.1 to 0.5% by weight, and iron 13 to 15% by weight is preferable because heat resistance, corrosion resistance, and mechanical properties at high temperatures can be secured.

The insulating layer 154 is charged inside the protective tube and serves to protect the wiring. it can be prevented

The insulating layer is preferably formed by filling the inside of the protective tube with an insulator such as magnesium oxide in the same manner as the tube. As described above, magnesium oxide is preferable because it has excellent heat resistance to protect the device from high temperatures, and maintains electrical insulation properties while having little physical and chemical change.

Hereinafter, a method of manufacturing a temperature sensor for measuring vehicle exhaust gas having the above structure will be described in detail.

A method of manufacturing a temperature sensor for measuring vehicle exhaust gas according to the present invention,

a) preparing a mineral insulated cable including a wiring, an insulator, and a protective tube;

b) bonding the wiring and the temperature element;

c) joining the tube to the protective tube so as to block the temperature element from the outside;

d) Oxidation treatment by heating the portion to which the protective tube is joined among both ends of the mineral insulated cable at a temperature of 1,000° C. or less, preferably at 900 to 1,000° C. for 2 to 20 hours, more preferably for 8 to 20 hours. step; and

e) filling the inside of the tube with a filler and sealing the tube;

may include.

First, step a) is a step of preparing a mineral insulated cable including a wiring, an insulator, and a protective tube, and more specifically, one or a plurality of wirings 151 provided at the center of the mineral insulated cable; an insulator layer 154 formed to surround the side surface of the wiring; and a protective tube 152 coated on a side surface of the insulator layer, and a lead wire 153 formed by extending an end of the wire that is not joined to the electrode wire of the temperature element among ends of the wire.

Step a) may be performed by first arranging two or more wires spaced apart from each other inside the protective tube, and then inserting an insulator into the protective tube. At this time, the wiring is not limited to the separation distance, but may be 1 to 15 mm, and the insulator is formed by mixing magnesium oxide powder with a solvent to make a dough, then injecting it into the protective tube and drying it in a drying furnace for a certain period of time to form an insulator layer can be formed

The insulator layer is preferably removed by drying the solvents for kneading in a drying furnace so that the content of magnesium oxide is 95% by weight or more out of 100% by weight of the total, as it does not exhibit conductivity or exothermicity.

The protective tube is made of metal and serves to protect the insulator layer and the wiring from external physical impact and at the same time block substances such as exhaust gas from being transmitted therein. In addition, since the protective tube maintains a predetermined thickness at a level to ensure flexibility, it can be freely bent or bent depending on the automobile parts to which the mineral insulated cable is applied.

The protective tube manufactured as described above can bond the wiring and the temperature element inside the protective tube as in step b).

Since the protective tube is made of metal as described above, one end of the edge of the protective tube may be cut using a laser to expose the wiring. If the edge is cut using a laser as described above, a clean cut surface can be obtained without going through a separate grinding process. can

In step b), after overlapping the electrode wire of the temperature element and the wiring of the mineral insulated cable, the overlapped portion may be joined by arc welding or laser welding.

Next, as in step c), the protective tube of the mineral insulated cable is combined with the tube. Among the ends of the protective tube of the mineral insulated cable, one end to which the temperature element is joined is inserted until it is caught on the step of the tube, and , it is preferable to join the end portion of the tube lower end and the tube welding portion of the protective tube to each other.

At this time, since the edge of the protective tube is cut using laser cutting as described above, the cut surface is clean, so that the inner surface of the stepped inside the tube and the cut surface of the protective tube can accurately contact each other without a separate polishing process. Can be assembled to match.

In step c), as in step b), the overlapping portion may be joined to the tube and the protective tube by a general welding method such as arc welding or laser welding.

Next, step d) is a step of oxidizing by exposing the portion to which the protective tube is joined among both ends of the mineral insulated cable to a high temperature.

In general, in the case of a temperature element, a metal pattern is printed on one or both sides of a ceramic substrate. The metal pattern is connected to the above-described electrode wire, and has the effect of extending the length of the circuit capable of measuring the temperature more than in the prior art, so that the resistance of the metal pattern can be measured at several points, and thus more accurate temperature measurement is possible.

The metal pattern is formed of a pure metal having a small resistivity, and among them, is formed of platinum. This is in order to stably measure the temperature of the exhaust gas emitted at a high temperature.

Such a temperature device, also called a resistance temperature detector (RTD), uses a PTC (Positive Temperature Coefficient) characteristic of a metal whose resistance value increases as the temperature increases, and measures the temperature inversely by measuring the resistance of the metal. The RTD device is very accurate and repeatable, and it is very stable over a long period of time. In addition, since it is a thin film, it has excellent thermal response, superior linearity compared to thermocouples and thermistors, and low production cost because it is manufactured using semiconductor manufacturing technology.

Among them, the RTD device made of platinum has excellent stability, linearity, chemical resistance, and corrosion resistance over a wide temperature range (-200°C to 540°C). In addition, as a basic resistance value, it has variously in the range of 100 to 1,000Ω, or more, and the higher the resistance value, the better the sensitivity and resolution. Here, the platinum pattern printed on the ceramic substrate has a resistance value greater than 1,000Ω at 0°C, and the change rate of the resistance value according to temperature is large, so the sensitivity is high, and the error caused by the lead wire resistance is small 3 It has the advantage of not requiring wire-type wiring.

However, since the metal pattern in the temperature element is formed of metal, and the exhaust gas of the vehicle contains about 8 to 14 wt % of water, there is a problem of corrosion, it is preferable to further provide a protective layer on the surface of the metal pattern . In this case, the protective layer is not formed in the portion where the electrode line and the wiring are joined, so it is preferable to secure the electrical connection of the metal pattern.

The protective layer may be formed of any material capable of forming an inorganic insulating film using various deposition methods within a temperature at which a thin film can be formed without damage to the temperature element, that is, 20 to 300°C.

For example, the inorganic insulating film may be formed of a vapor-depositable material such as aluminum oxide, zinc oxide, titanium oxide, tantalum oxide, zirconium oxide, hafnium oxide, silicon dioxide, silicon nitride, aluminum nitride, aluminum nitride, etc., preferably It is preferably formed of a ceramic material such as silicon dioxide.

The silicon dioxide is strong in thermal shock and has the advantage of protecting high-purity platinum from impurities outside the thermometer. However, the silicon dioxide reacts with oxygen in air at a temperature of 1,100° C. or higher to form a silicon dioxide (SiO ₂ ) insulating film, but when the silicon dioxide does not properly contact with oxygen, silicon monoxide (SiO) It can be generated in gaseous form. Since the silicon monoxide gas acts as a corrosion factor of platinum and can destroy the platinum pattern, it is preferable to completely form the silicon dioxide insulating film by heating in a state in which oxygen is sufficiently added. In addition, in order to completely protect the surface of the platinum element with an insulating film, it is preferable to proceed without charging magnesium oxide during the heat treatment as described above.

The method for forming the inorganic insulating film is not limited. For example, methods such as atomic layer deposition, physical vapor deposition, chemical vapor deposition, and hot-dip plating may be applied.

In the present invention, in step d), as shown in FIG. 5 , it is preferable to oxidize the portion to which the protective tube is joined among both ends of the mineral insulated cable by heating it in an atmospheric atmosphere and at a temperature of 1,000° C. or less for 8 to 20 hours. In this case, in more detail in step d),

d1) putting the tube into a heating furnace and heating it for 30 to 60 minutes while raising the temperature from room temperature to 1,000° C. or less, more preferably from 950 to 1,000° C.;

d2) leaving the tube for 480 to 1,200 minutes while maintaining the heating furnace at a temperature of 1,000° C. or less; and

d3) naturally cooling the heating furnace in the heating furnace to lower the temperature to 200°C;

It is preferable to proceed with

In general, when a sensor made of a noble metal such as platinum is used at a high temperature for a long time, impurities may be adsorbed on the surface of the pure platinum wire, resulting in a change in characteristics, and due to grain growth, a bamboo structure may occur. Long-term stability may be deteriorated or the wire may be short-circuited.

Therefore, an insulating layer is coated on the surface of the sensor to prevent the sensor from destructive behavior such as short circuit. The insulating layer is mostly made of a ceramic structure such as silicon dioxide, and may be formed by heating a silicon component formed on the surface of the sensor in an oxygen atmosphere.

The problem is that even when heating in an atmosphere containing oxygen when forming the insulating layer, if the heating temperature is too high or the supply of oxygen is intermittent, low molecular weight components present in the insulating layer from the beginning or silicon monoxide ( Scattering or sublimation of low molecular weight components such as SiO) may occur. In particular, silicon monoxide is highly reactive and when exposed to air, the surface is oxidized to form silicon dioxide, and this reaction occurs instantaneously. As a result, there may be a problem that the insulating layer is not generated inside the insulating layer or the inside of the sensor.

Therefore, the temperature sensor according to the present invention forms an insulating layer containing silicon dioxide to protect the internal temperature element, and it is preferable to adjust the heating temperature and the heating atmosphere for sufficient formation of the silicon dioxide.

In the present invention, the reason for the temperature increase-maintenance-cooling in each step as described above is to maintain a constant temperature and heating time applied to the tube. That is, the step d1) is a temperature increase step for maintaining the same temperature inside the heating furnace and the heating furnace itself, and it is possible to prevent heat loss or heat change due to the temperature difference, and in step d2), a temperature of 1,000° C. or less An oxide film (SiO ₂ ) can be generated on the temperature element in the tube while continuously maintaining the temperature.

In addition, in step d), it is preferable to proceed the heating furnace in an atmospheric atmosphere, more preferably in a pure oxygen atmosphere. Because it is important to continuously supply oxygen during heating in order to create an oxide film on the temperature element, oxygen in the air (about 21%) contains various components included in the above-mentioned hot-dip aluminum plating or hot-dip zinc plating, especially silicon. and may form an oxide film having insulating properties.

In addition, the temperature element is preferably formed on both the inner wall of the tube and the mineral insulated cable as well as the temperature element in the tube in order to form a sufficient oxide film (insulating layer) therein.

5, the temperature element is charged inside the heating device 200 provided with the door 210, the furnace 220, and the jig 230 to form an insulating layer, and the heating This can be carried out by heating the device in a state in which air or oxygen is supplied. At this time, the temperature element is not all put into the furnace, but a part of the tube 120 and the mineral insulated cable 150 bonded to the tube is exposed inside the furnace to be heated.

In addition, the tube is not sealed with the cap 110, it is preferable to heat in a state in which the filler is not filled. That is, since the atmosphere or oxygen in the furnace is sufficiently supplied to the inside of the tube, the insulating layer may be sufficiently formed in the temperature element as well as the electrode wire, the mineral insulated cable and the tube.

Next, as in step e), a filler may be filled inside the tube, and the tube may be sealed.

The tube may have both ends open, and one end may be sealed by the above-described cap, and it is preferable to fill the powder-type filler before sealing. In this case, it is preferable to use magnesium oxide as the filler. The magnesium oxide is charged to ensure insulation. As described above, when the cap 110 is coupled to the tube 120 as described above, the magnesium oxide filled inside by the convexly protruding end 113 as described above. As the powder is pressed by the protruding surface of the protruding end 113 , it is possible to remove microbubbles that may be formed in the magnesium oxide powder.

The magnesium oxide is a kind of insulator, which is tightly filled in the space formed between the inner circumferential surface of the tube and the outer circumferential surface of the temperature element, and shields the space, while having heat resistance, substantially heat conduction between the inner circumferential surface of the tube and the outer circumferential surface of the temperature element It serves as a link to make it possible. In particular, aluminum oxide is preferable because it has excellent heat resistance, can protect the device from high temperatures, and maintains electrical insulation properties while having little physical and chemical change.

However, in the present invention, only magnesium oxide is limited as the insulator, but if it is an insulating material having heat resistance similar to magnesium oxide such as zinc oxide, boron nitride, aluminum oxide, zirconium oxide, aluminum nitride, silicon nitride and cement, the magnesium oxide is used. It can be replaced, and one or two or more of these insulators may be used in combination.

In the present invention, the insulator is preferably filled in the form of a powder, and in this case, the particle diameter of the insulator is preferably in the range of 1 nm to 1,000 μm to minimize the formation of voids that may occur due to aluminum oxide after charging.

The cap is preferably joined through a general welding method such as arc welding or laser welding as in step b), and after the cap is joined, the cylindrical flange 140 with both ends open is connected to the mineral insulated cable ( 150) may further include a configuration for bonding after passing through.

When the temperature sensor is actually assembled with other parts of the exhaust gas system of a vehicle, the flange may perform a sealing function in combination with a connection part such as an exhaust gas pipe.

Also, after joining the flange, the lead wire 153 protruding from the other end of the mineral insulated cable may be shaped so as to be coupled to the device to be mounted.

As the connection method of the other end of the mineral insulated cable, various connection methods such as a connection fitting, a connector, a terminal block, a lead wire, etc. may be used. In one embodiment of the present invention, the connection using the lead wire 153 is exemplified.

Hereinafter, the temperature sensor according to the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the following examples and comparative examples are merely examples for explaining the present invention in more detail, and the present invention is not limited to the following examples.

The physical properties of the specimens prepared in Examples and Comparative Examples were measured as follows.

(resistance change)

The low temperature change of the temperature sensor prepared through the following Examples and Comparative Examples was measured. The measurement standards are shown in Table 1 below, and the initial resistance value is a value measured at room temperature (25°C) and high temperature (1,000°C) immediately after manufacturing including heat treatment, and the resistance value after durability is maintained at 1,000°C. The resistance values at room temperature (25° C.) and high temperature (1,000° C.) were measured after 5,000 repeated tests of 5 minutes left in a high-temperature furnace and 5 minutes left at room temperature (25° C.). The maximum resistance value and the minimum resistance value were measured for the resistance value, and if the measured resistance value was between the maximum resistance value and the minimum resistance value, it was judged as good, otherwise it was judged as bad.

[Table 1]

(temperature Senser)

Specifications for each component of the temperature sensor manufactured through the following Examples and Comparative Examples are shown in Table 2 below.

[Table 2]

(Examples 1 to 4 and Comparative Examples 1 to 8)

A temperature sensor was manufactured from the material having the specifications in Table 2 above. At this time, five temperature sensors (specimen) having the same composition were prepared for each Example, and the temperature sensors were heat-treated under the conditions of Tables 3 and 4 below before filling the tube with magnesium oxide. After heat treatment, the physical properties of the five temperature sensors prepared as described above were respectively measured, and the resistance values were measured once after durability, and are shown in Tables 4 and 5 below.

[Table 3]

(In Table 4, the heating atmosphere of Comparative Examples 2 and 3 is a gas in which hydrogen: nitrogen = 1:1 weight ratio, ammonia: nitrogen = 1:1 weight ratio, respectively.)

[Table 4]

[Table 5]

As shown in Tables 4 and 5, it can be seen that the temperature sensors manufactured according to the present invention have practical resistance values at room temperature and high temperature compared to Comparative Examples, and thus are suitable for use as a temperature sensor. Specifically, it can be seen that all of the initial resistance values are good when the heat treatment temperature is 950 to 1,000°C as shown in Tables 4 and 5 above. However, when the heat treatment time was maintained at 2 hours, 4 hours, and 6 hours, respectively, it was confirmed that the resistance values after standing at a high temperature were all outside the range of Table 1. This is due to the lack of time for forming the oxide film on the surface of the temperature element, and it is inappropriate to use it as a temperature sensor, so it can be seen that the heat treatment time should be maintained for at least 8 hours.

In addition, in Comparative Examples 4 and 5 in which the heat treatment temperature was set to 1,000° C. or higher, the initial resistance value was good, but it was confirmed that the resistance value after being left at a high temperature was out of the reference range. This is because the thickness of the oxide film is thin and not properly formed due to the insufficient heat treatment time, and in addition, the device itself is deformed due to rapid thermal shock, resulting in decreased stability. Therefore, it was found that the appropriate temperature during heat treatment should be carried out at 1,000 °C or less.

Here, Comparative Example 1, in which no heat treatment was performed at all, and Comparative Examples 2 and 3, in which the heat treatment was performed under hydrogen + nitrogen, ammonia + nitrogen atmosphere, did not properly form an oxide film, so even the initial performance did not satisfy the standards of the present invention. sound could be confirmed.

As described above, various embodiments of the present invention have been presented and described, but the present invention is not necessarily limited thereto. It will be readily appreciated that branch substitutions, transformations and alterations are possible.

100: temperature sensor
110: cap
111: cap body
112: merging part
113: protruding end
120: tube
121: upper tube
122: step
123: tube bottom
124: tube welding part
130: temperature element
131: electrode wire
140: flange
141: flange top
142: bottom of flange
150: mineral insulated cable
151: wiring
152: protection officer
153: lead wire
154: insulator layer
200: heating device
210: door
220: furnace
230: jig

Claims (6)

a) preparing a mineral insulated cable including a wiring, an insulator, and a protective tube;
b) bonding the wiring and the temperature element;
c) joining the tube to the protective tube so as to block the temperature element from the outside;
d) forming a silicon dioxide insulating film by heating the portion to which the protective tube is bonded among both ends of the mineral insulated cable at a temperature of 900 to 1,000° C. and an atmospheric atmosphere for 8 to 20 hours; and
e) filling the inside of the tube with a filler and sealing the tube;
Including, wherein the step d),
d1) putting the tube into a heating furnace and heating the tube for 30 to 60 minutes while raising the temperature from room temperature to 950 to 1,000°C;
d2) leaving the tube for 480 to 1,200 minutes while maintaining the heating furnace at a temperature of 1,000° C. or less; and
d3) naturally cooling the heating furnace in the heating furnace to lower the temperature to 200°C;
containing
A method of manufacturing a temperature sensor for measuring automobile exhaust gas.
delete delete delete The method of claim 1,
The wiring, the protective tube and the tube,
Aluminum, carbon, chromium, copper, iron, manganese, nickel, sulfur, silicon, nitrogen, zirconium, molybdenum, titanium, niobium and a temperature sensor for measuring vehicle exhaust gas comprising at least two materials selected from phosphorus manufacturing method.
The method of claim 1,
The filler is magnesium oxide, zinc oxide, boron nitride, aluminum oxide, zirconium oxide, aluminum nitride, silicon nitride, and a method of manufacturing a temperature sensor for measuring vehicle exhaust gas, characterized in that any one or a plurality selected from cement.

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