JP6279284B2 - Temperature sensor - Google Patents

Description

  The present invention relates to a temperature sensor that can measure temperature accurately over a long period of time, for example, in a high temperature atmosphere of 500 ° C. or higher.

  Temperature sensors using a thermistor whose electrical resistance varies with temperature are widely used to measure the temperature inside equipment such as electric ovens, radiant heaters, water heaters, combustion appliances, exhaust gas purifiers, boilers, burners, and stoves. Has been. The thermistor element used in this temperature sensor has a temperature sensing element composed of a thermistor and a pair of lead wires connected to the temperature sensing element via electrodes, and protects against vibration, external force, combustion gas, and the like. It is housed in a metal protection tube. Usually, the temperature sensing element is sealed with a sealing material made of heat resistant glass.

The present applicant has proposed a temperature sensor that can withstand use in a high temperature atmosphere of, for example, 500 to 1000 ° C. in Patent Document 1 and Patent Document 2.
The temperature sensor of Patent Document 1 prevents the occurrence of a leakage current generated between lead wires by evaporating a conductive substance (a constituent element of the metal) from a protective tube that houses a thermistor element and filling between the lead wires. For the purpose. In order to achieve this object, the temperature sensor of Patent Document 1 covers a lead wire with a ceramic shield.
Moreover, the temperature sensor of patent document 2 implement | achieves lengthening according to the length of the heat-resistant wire with a covering by connecting a heat-resistant wire with a cover to the lead wire of a thermistor element.

JP 2010-261860 A WO2013 / 072961

The present inventors have proposed a temperature sensor that can withstand use in a high-temperature atmosphere, but it is required to be able to withstand use for a long period of time depending on the application.
On the other hand, it may be required to measure temperatures at different positions in a high temperature atmosphere. For example, when measuring the temperature of two measurement points separated from each other, two temperature sensors disclosed in Patent Document 1 or Patent Document 2 are prepared so that each thermistor element corresponds to the measurement point. Two temperature sensors may be arranged. However, it may not be possible to secure a space for arranging the two temperature sensors. If two temperature sensors are prepared, the cost of the entire temperature sensor is doubled, which increases the cost of the applied device.
The present invention has been made based on such a problem, and an object of the present invention is to provide a temperature sensor that can be used for a long time in a high temperature atmosphere.
Furthermore, an object of the present invention is to provide a temperature sensor that can reduce the occupied space for measuring the temperature at a plurality of measurement points and can be manufactured at low cost.

For this purpose, the temperature sensor of the present invention has a protective tube made of a heat-resistant alloy with the front end side sealed and the rear end side opened, and a thermistor element housed inside the protective tube. And a sensor unit including a pair of electric wires to be connected and a heat-resistant insulating coating layer covering the thermistor element.
In the temperature sensor of the present invention, the protective tube is provided with an air passage that communicates the inside and the outside by opening the rear end side, and an oxide film is previously formed on the surface thereof.
The thermistor element includes a temperature sensor made of a thermistor and a lead wire made of a noble metal connected to the temperature sensor through an electrode.
Each of the pair of electric wires includes a core wire made of a heat-resistant alloy to be connected, and a covered electric wire including an insulating covering covering the periphery of the core wire, and the core wire of the covered electric wire is accommodated in at least a protective tube. An oxide film is previously formed in the region to be formed.

  When the temperature sensitive body is reduced, the characteristics thereof change, and the accuracy of the detected temperature may be reduced. Therefore, the temperature sensor of the present invention is provided with a ventilation path that communicates the inside and the outside of the protective tube so that oxygen can be supplied to the temperature sensing element.

In the temperature sensor of the present invention, an oxide film is formed on the surface of the protective tube in advance in order to make the effect of preventing reduction by the air passage more remarkable. This is because when the temperature sensor of the present invention is used in a high temperature atmosphere and the protective tube is oxidized, the temperature sensing element housed in the protective tube may be reduced depending on the degree of oxidation.
The term “preliminarily” used in the present invention means that the temperature sensor is not yet used for the purpose of measuring temperature, and typically corresponds to a manufacturing process of the temperature sensor.

  Furthermore, considering that the electric wire connected to the temperature sensing element is used in a high temperature atmosphere, the electric wire is preferably made of a noble metal. However, since an electric wire made of a noble metal is expensive, the present invention uses only a part thereof and uses a covered electric wire for the other part. If it is a noble metal, even if it is used in a high temperature atmosphere, there is almost no fear of oxidation, but the portion made of a heat-resistant alloy cannot be denied. Therefore, the core wire of the covered electric wire suppresses the reduction of the temperature sensitive body by previously forming an oxide film in the region accommodated in the protective tube.

In the temperature sensor of the present invention, one or both of the heat-resistant insulating coating layer and the insulating coating body are subjected to an oxidation treatment that forms an oxide film on the core wire together with the core wire, thereby reducing the organic component that consumes oxygen by combustion. It is preferred that
The heat-resistant insulating coating layer may contain an organic component (carbon) due to its manufacturing process, and this organic component burns and consumes oxygen inside the protective tube.
In addition, when using a braided body made of glass fiber or ceramic fiber as the insulating covering, the braided body is usually bundled with fibers by a converging material in order to prevent the braided fibers from being scattered. Yes. Since this converging material contains carbon, when heated in the course of using the temperature sensor, carbon combines with oxygen and consumes oxygen inside the protective tube.
Then, the organic component which consumes oxygen by combustion is reduced by using one or both of a heat-resistant insulating coating layer and an insulation coating body with an oxidation process with a core wire.

In the temperature sensor of the present invention, the heat-resistant alloy constituting the protective tube and the heat-resistant alloy constituting the core wire of the covered electric wire are preferably made of a matrix-reinforced Ni-base superalloy.
The matrix-strengthened Ni-base superalloy can perform the functions of the protective tube and the core wire even in a high temperature atmosphere where the use of a temperature sensor is expected. In addition, the matrix-reinforced Ni-base superalloy can keep the formed oxide film within the necessary range of the surface layer portion when the oxidation treatment is performed in advance, and is a base for realizing heat resistance excluding the oxide film. A sufficient portion can be secured.
As the matrix-reinforced Ni-base superalloy, JIS NCF600 and JIS NCF601 are preferable. In particular, the protective tube is preferably JIS NCF601, and the core wire of the covered electric wire is preferably JIS NCF600.

  As a temperature sensor to which the present invention is applied, a metal protective tube whose front end side is sealed and a rear end side is opened, a first thermistor element is accommodated in the protective tube, and the first thermistor element is electrically connected. A first sensor unit including a pair of first electric wires connected to the first and second protection thermistors, and the second thermistor is housed in a position different from the position where the first thermistor element is housed. A second sensor unit including a pair of second electric wires electrically connected to the element, a first holder for positioning and fixing the first electric wire of the first sensor unit, and a second electric wire of the second sensor unit A holder assembly configured by combining the first holder and the second holder is fitted into the opening on the rear end side of the protective tube. preferable.

According to the temperature sensor of the present invention, since two thermistor elements are provided at different positions inside one protective tube, the occupied space can be suppressed compared to housing two sensor units in separate protective tubes. And cost can be reduced.
Moreover, according to the present invention, each sensor unit is fixed to the corresponding holder, and then the holder is assembled and fixed. Accordingly, each thermistor element of the sensor unit can be arranged at a predetermined position of the protective tube without causing a relative positional shift, so that the temperatures at two measurement points required in a high temperature atmosphere can be detected with high accuracy. be able to.

  In the holder of the present invention having two sensor units, the holder assembly provides an air passage that communicates the inside and the outside of the protective tube. This is to ensure that oxygen is supplied to the temperature sensitive body.

According to the temperature sensor of the present invention, since the protective tube functions as an air passage, oxygen can be supplied to the temperature sensing body through the air passage. Moreover, since the temperature sensor of the present invention forms an oxide film on the core wire of the covered electric wire made of a protective tube and a heat-resistant alloy, it is possible to prevent the temperature from being oxidized in the process of being used in a high temperature atmosphere. Reduce body reduction.
Next, according to the present invention, since two thermistor elements are provided at different positions inside one protective tube, the occupied space can be reduced compared to housing two sensor units in separate protective tubes. And cost can be reduced.
Moreover, according to the present invention, each sensor unit is fixed to the corresponding holder, and then the holder is assembled and fixed. Therefore, each thermistor element of each sensor unit can be arranged at a predetermined position of the protective tube without causing a relative displacement, so that the temperature at the two measurement points required in a high temperature atmosphere can be obtained with high accuracy. Can be detected.

It is a figure which shows the temperature sensor by 1st Embodiment of this invention. It is a graph which shows the weight change rate per unit time when an oxidation process is performed. (A) is a table | surface which shows the evaluation result when performing the oxidation process to the lead wire and covering electric wire which were connected by welding, (b) shows a mode that the oxide segregated to the welding interface. It is a figure which shows the whole temperature sensor by 2nd Embodiment of this invention. It is a figure which shows the sensor precursor used for the temperature sensor of FIG. 4, (a) shows the precursor which connected the heat-resistant electric wire to the thermistor element, (b) connected the extension lead wire to the precursor of (a). (C) shows a first sensor unit in which the precursor of (b) is assembled to the first holder, and (d) shows a second sensor in which the precursor of (b) is assembled to the second holder. Indicates a unit. It is a figure which shows the holder used for the temperature sensor of FIG. 4, (a) shows the top view and side view of a 1st holder, (b) has shown the top view and side view of a 2nd holder. It is a figure which shows the assembly | attachment of the temperature sensor of FIG. It is a figure which shows the other example of the sensor unit used for the temperature sensor of FIG. 1 and FIG.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
[First Embodiment]
As shown in FIG. 1, the temperature sensor 1 according to the first embodiment includes a sensor unit 10 and a metal protective tube 30 that houses a main part of the sensor unit 10.
The temperature sensor 1 is attached to a device that generates a high temperature atmosphere of, for example, 500 ° C. or more, and can accurately measure the temperature over a long period of time.

[Sensor unit 10]
The temperature sensor 1 includes a sensor unit 10.
As shown in FIG. 1, the sensor unit 10 includes a temperature sensing element 11 whose electrical resistance changes according to temperature, and a pair of lead wires 15 electrically connected to the temperature sensing element 11 via electrodes not shown. A sealing material 17 that seals the lead wires 15 within a predetermined range from the temperature sensing element 11 and a pair of covered electric wires 16 connected to each of the pair of lead wires 15 are provided. Here, although the temperature sensing element 11 has improved durability by suppressing the influence of the outside air by the sealing material 17, the characteristics may inevitably change due to the influence of the outside air. Therefore, the temperature sensor 1 secures an air passage by the protective tube 30 in order to prevent the temperature sensing body 11, the lead wire 15 and the sealing material 17 from being exposed to a reducing atmosphere in order to further improve the durability. Each member is oxidized. The thermistor element 12 is composed of the temperature sensing element 11 and the pair of lead wires 15.
Details of each element will be described below.

  Although the thermistor 11 is preferably used as the temperature sensing element 11, the temperature is measured by utilizing the fact that the electric resistance changes depending on the temperature. The thermistor used in a high temperature range of 500 ° C. or higher includes, for example, Y, Cr, Mn, Ca and O, and the molar ratio of Y: Cr: Mn: Ca is 75 to 85: 7 to 10: 7 to 10. : It is preferable to use the metal oxide which is 1-5. The temperature sensing element 11 composed of this metal oxide can measure the temperature up to a high temperature of 1000 ° C. or higher. However, this is only an example, and it goes without saying that other thermistors can be used.

  The lead wire 15 can be made of a noble metal, particularly platinum or a platinum alloy. As a platinum alloy, what contains 1-20 mass% of iridium is preferable from a heat resistant viewpoint.

The sealing material 17 contributes to the improvement of the durability of the temperature sensing body 11 by covering the temperature sensing body 11 so that the temperature sensing body 11 is not affected by outside air. The sealing material 17 is made of amorphous glass or crystalline glass. They can be used alone, but it is also possible to use a mixture of amorphous glass and crystalline glass so as to have a desired thermal expansion coefficient. As the crystalline glass, for example, those composed of silicon oxide, calcium oxide, magnesium oxide, and aluminum oxide are preferable. More specifically, SiO ₂ : 30 to 60% by mass, CaO: 10 to 30% by mass, MgO : 5 to 25 _{wt%, Al} 2 O 3: those having a composition of 0-15 wt% can be used in the present invention. Moreover, you may comprise using what added inorganic material powder to glass. Examples of the inorganic material powder added to glass include aluminum oxide (Al ₂ O ₃ ), magnesium oxide (MgO), yttrium oxide (Y ₂ O ₃ ), chromium oxide (Cr ₂ O ₃ ), zirconium oxide (ZrO ₂ ), and the like. The metal oxide which comprises the temperature sensing body 11 is mentioned.

The covered electric wire 16 is, for example, sufficient to cover the core wire 16a having heat resistance with the insulating covering body 16b having higher heat resistance than the core wire 16a, and to ensure insulation of the core wire 16a even in a high temperature atmosphere of 500 ° C. or higher. In addition, a material having high insulation can be used.
Each of the core wire 16a and the insulation coating body 16b has a heat resistant temperature corresponding to the operating temperature of the temperature sensor 1. Moreover, by covering the core wire 16a with the insulation coating body 16b, it is possible to ensure insulation of the core wire 16a in a high temperature atmosphere, that is, to insulate from the protective tube 30 and to prevent a short circuit between the wires.
As the core wire 16a, for example, Ni, a stainless alloy, a Ni-base superalloy, other heat-resistant alloys, or the like can be used. These alloys contain a large amount of Ni and Cr in order to improve heat resistance. For example, the chemical composition of JIS NCF600, which is an example of a Ni-base superalloy, is defined in JIS G4902, but contains about 72% Ni and about 15% Cr. In addition,% is the mass%. Illustrating the approximate normal heat-resistant temperature of the core wire 16a for each material, Ni is about 500 ° C., stainless alloy: about 600 ° C., and JIS NCF 600: about 800 ° C.
[NCF600 chemical composition]
C ≦ 0.15% Si ≦ 0.50% Mn ≦ 1.00% P ≦ 0.030% S ≦ 0.015% Cr: 14.00 to 17.00% Cu ≦ 0.50 Fe: 6.00 to 10.00% Remaining: Ni + impurity NCF600 is a matrix together with NCF601 described later. It is known as a reinforced Ni-base superalloy.

As the insulating covering 16b, for example, a braided tube of glass fiber or ceramic fiber is used. As the main component _can be exemplified by _{SiO 2, Al 2 O 3,} Si 3 N 4 or the like. Examples of the approximate heat-resistant temperature of the insulating covering 16b for each material are glass fiber braid: about 500 ° C., silica glass fiber braid: about 1000 ° C., ceramic fiber braid: about 1300 ° C.
For the purpose of improving the insulation property of the covered electric wire 16 at a high temperature, a glass fiber or a ceramic fiber is interposed between the core wire 16a and the insulating covering body 16b, or a tape made of mica paper and a backing material is interposed. Or you may.
The covered electric wire 16 is connected to the lead wire 15 at one end side. The covered electric wire 16 extends along the axial direction of the protective tube 30, and the other end is drawn out of the protective tube 30 and connected to a measurement circuit (not shown) via another electric wire.

The connecting portion C between the lead wire 15 and the core wire 16a is covered with a heat-resistant insulating coating layer 18 as a protective material. The heat-resistant insulating coating layer 18 includes ceramic particles and an inorganic binder that bonds the ceramic particles to each other, and has high heat resistance of 1000 ° C. or higher and insulating properties. As the ceramic particles, for example, one having at least one of Al ₂ O ₃ , SiO ₂ , ZrO ₂ , ZrSiO ₄ , MgO, Y ₂ O ₃ , and AlN as a main component can be used. As the inorganic binder, ceramic, glass, or the like can be used.
Such a heat-resistant insulating coating layer 18 covers the entire outer periphery of the sealing material 17 including the connection portion C, that is, the periphery of the thermistor element 12.
Before being provided at a predetermined position, the heat-resistant insulating coating layer 18 contains a solvent (for example, water, an organic solvent, and a metal alkoxide) and has fluidity. After covering the periphery of the sealing material 17, the heat-resistant insulating coating layer 18 is dried by heating. It is formed by curing. For example, a material used as a coating material, an adhesive, or a sealing material can be used as the heat-resistant insulating coating layer 18.

[Protection tube 30]
The sensor unit 10 having the above configuration is accommodated in the protective tube 30 from the thermistor element 12 to the covered electric wire 16 and is assembled to the protective tube 30.
As shown in FIG. 1, the protective tube 30 is closed at the front end 31 on the side where the thermistor element 12 is disposed, while the rear end 33 is opened, so that the sensor unit 10 accommodated therein can be vibrated or subjected to external force. A cylindrical member that protects against high heat and combustion gases. The protective tube 30 includes a flange 35 on the side close to the rear end 33 for attaching to the casing 40 of the target device whose temperature is to be measured. Since the inside of the protective tube 30 communicates with the outside of the housing 40, the inside of the protective tube 30 functions as a ventilation path. Although the length L from the front end 31 to the flange 35 can be set according to the apparatus to which it is attached, it can be set to about 500 mm, for example. The front end 31 of the protective tube 30 also serves as the front end of the temperature sensor 1. In FIG. 1, the rear end 33 is completely open. However, for example, a holder that holds the covered electric wire 16 is placed at the rear end 33 to such an extent that ventilation can be performed between the inside of the protective tube 30 and the outside (atmosphere). The covered electric wire 16 and the protective tube 30 can be fixed by caulking the rear end 33.
As a material constituting the protective tube 30, for example, stainless steel, a Ni-base superalloy, or other heat-resistant alloy can be used. For example, the chemical composition of JIS NCF601, which is an example of a Ni-based superalloy, is defined in JIS G4902, and contains about 60% by mass of Ni, 23% by mass of Cr, and about 1.4% by mass of Al.
[NCF601 chemical composition]
C ≦ 0.10% Si ≦ 0.50% Mn ≦ 1.00% P ≦ 0.030% S ≦ 0.015% Cr: 21.00 to 25.00% Cu ≦ 1.00% Co: 1.00 to 1.70% Ni: 58.00 to 63.00% Remainder: Fe + impurities

[Oxidation treatment]
The temperature sensor 1 has a structure that prevents the temperature sensing body 11 from being reduced by causing the protective tube 30 to function as an air passage. However, in order to make the reduction prevention effect more prominent, the temperature sensor 1 is protected. It is preferable to subject the tube 30 and the sensor unit 10 to an oxidation treatment. Hereinafter, this oxidation treatment will be described.

The protection tube 30 is first listed as an object of the oxidation treatment. The protective tube 30 is made of a heat-resistant alloy, but its inner surface is oxidized when exposed to a high temperature atmosphere. As a result, the inside of the temperature sensing element 11 is reduced and the oxygen is consumed for oxidation, so that the temperature sensing element 11 is reduced. If it does so, detection accuracy falls.
Therefore, in the process of manufacturing the temperature sensor 1, the protective tube 30 is preliminarily oxidized to form an oxide film on the surface. If it does so, in the process of using the temperature sensor 1, since consumption of the oxygen inside the protective tube 30 can be suppressed, reduction | restoration of the temperature sensing body 11 can be suppressed. Hereinafter, the effect of the oxidation treatment when the protective tube 30 is configured by JIS NCF601 will be described.

The oxidation treatment held in the heat treatment furnace at the following holding temperature and holding time was performed, and the weight change rate per unit time was determined.
The result is shown in FIG. 2. If the retention time of the oxidation treatment exceeds 8 hours, the rate of change in weight per unit time becomes small. It can be seen that consumption of oxygen due to oxidation of the protective tube 30 in the process of using the sensor 1 can be suppressed.
Holding temperature: 800 ° C, 900 ° C, 950 ° C, 1000 ° C
Retention time: 2 hr., 4 hr., 8 hr., 16 hr., 24 hr., 48 hr., 100 hr.

  It is desirable that the conditions for forming an oxide film on the protective tube 30, particularly the holding temperature, consider the temperature of the atmosphere in which the protective tube 30 is used as the temperature sensor 1. In addition, if the thickness of the formed oxide film is too thin, the effect of reducing the consumption of oxygen is insufficient. On the other hand, if it is too thick, the oxide film may drop off and the film thickness tends to be non-uniform. Therefore, the conditions for the actual oxidation treatment are determined in consideration of the material constituting the protective tube 30 and the atmosphere of the oxidation treatment.

  In the present embodiment, the sensor unit 10 is subjected to oxidation treatment in addition to the protective tube 30. More specifically, in the sensor unit 10, the core wire 1 a and the insulation coating body 16 b of the covered electric wire 16 and the heat-resistant insulation coating layer 18 are directly subjected to oxidation treatment. Hereinafter, actions and effects of the oxidation treatment will be described in this order.

Since the core wire 16a is housed inside the protective tube 30, it can be oxidized during use of the temperature sensor 1. Therefore, although this embodiment makes it the object of the oxidation process which performs the core wire 16a previously, when the present inventors conducted the experiment which exposes to the core wire 16a at 1200 degreeC for 100 hours time, as demonstrated below, Interesting results were obtained.
In this embodiment, since the core wire 16a is connected to the lead wire 15 by welding, the lead wire 15 and the core wire 16a of the assumed material were exposed to an oxidizing environment in a welded state. This is because there is a concern about the adverse effect that the electrical resistance of the welded portion increases due to oxidation. FIG. 3A shows the measurement result of the electrical resistance of the welded portion and the oxidation state depending on the material of the core wire 16a and the lead wire 15. FIG. Note that the oxidation treatment was performed under accelerated conditions of holding at 1200 ° C. for 100 hours. The lead wire 15 was made of a Pt alloy containing 10% by mass of Ir.
Note that alumel, chromel and Kanthal in FIG. 3A are registered trademarks.

Depending on the material of the core wire 16a, as shown in FIG. 3 (b), the oxide O segregated at the joint interface B between the core wire 16a and the lead wire 15, and a tendency to significantly deteriorate the electrical resistance of the welded portion was observed. When the composition of the generated oxide including the oxide segregated at the bonding interface was identified by EDX (Energy dispersive X-ray spectrometry), it was an oxide containing aluminum. Each of the core wires 16a in which the aluminum oxide is generated contains Al exceeding 4% by mass.
Further, as shown in FIG. 3A, depending on the material, oxidation proceeds to the inside of the core wire 16a and cannot function as an electric wire.
Therefore, as the core wire 16a, it is possible to select a material having an Al content of 2% by mass or less and excluding impurities substantially free of Al so as not to segregate the aluminum oxide at the bonding interface. preferable. According to the study by the present inventors, JIS NCF600 is most preferable as the core wire 16a.

Next, in the present embodiment, the insulating covering body 16b is subjected to oxidation treatment.
As described above, the insulating cover 16b is made of a braid of glass fiber or ceramic fiber. In this braid, the fibers are bundled by a converging material in order to prevent the braided fibers from being scattered. Since this converging material contains an organic component, that is, carbon (C), when it is heated in the process of using the temperature sensor 1, the carbon contained in the converging material is combined with oxygen, and the inside of the protective tube 30. Consume oxygen. Therefore, in the present embodiment, the insulating covering 16b is an object of oxidation treatment, and carbon contained in the converging material is combined with oxygen to remove carbon in advance. In addition, in the protective tube 30 and the core wire 16a, the oxidation treatment is intended to form an oxide film, but for the insulating coating body 16b, the oxidation treatment is intended to remove carbon, both of which are oxidation treatments. Is the same, but the purpose is different.

  In the present embodiment, the heat-resistant insulating coating layer 18 is also subject to oxidation treatment, but the heat-resistant insulating coating layer 18 also contains carbon when produced using an organic solvent or metal alkoxide. If there is something that has become unreacted during normal drying and curing, the remaining organic components are combusted by heating in the process of using the temperature sensor, and oxygen in the protective tube is consumed. For the reason, it is subject to oxidation treatment.

Hereinafter, an example of a procedure for manufacturing the temperature sensor 1 will be described.
First, the lead wire 15 is joined to the electrode of the manufactured temperature sensor 11, and then, for example, a glass material constituting the sealing material 17 is provided in a melted state around the temperature sensor 11 by a known method. Cool and cure. What hardened | cured this glass material becomes the sealing material 17 which covers the temperature sensing body 11 and the predetermined range of the lead wire 15. FIG.

  Next, the core wire 16 a of the covered electric wire 16 is welded to the lead wire 15. When the sealing material 17 is formed after the core wire 16a is welded to the lead wire 15, the connection portion C is reheated due to the influence of melting of the glass material (heat conduction from the molten glass material to the lead wire 15). Since this may cause oxidation deterioration of the connection portion C, it is preferable to weld the lead wire 15 after forming the sealing material 17.

  Next, after dipping from the front end of the sealing material 17 to the rear end of the connection portion C in the heat-resistant insulating coating layer 18 before drying and curing put in the container, the container is pulled up from the container. Thereafter, in the process of heating and drying and curing the heat-resistant insulating coating layer 18, the solvent is released and the ceramic particles are bonded together by the molten inorganic binder, thereby providing the heat-resistant insulating coating layer 18.

The sensor unit manufactured so far is subjected to oxidation treatment.
The conditions for the oxidation treatment are as described above. By the oxidation treatment, an oxide film is formed on the core wire 16a of the covered electric wire 16, and the organic component (carbon) and heat-resistant insulation coating contained in the converging material of the insulation coating body 16b. Residual organic components of layer 18 are removed.
The protective tube 30 can be oxidized in the same process as that of the sensor unit, or can be oxidized in a process separate from the sensor unit.
In this oxidation treatment, the combustion temperature of the organic component is measured using, for example, differential thermal-thermogravimetric simultaneous measurement (TG-DTA), and the heating temperature is specified based on the measured temperature. In the case of the residual organic components of the insulating coating body 16b and the heat-resistant insulating coating layer 18 in this embodiment, the oxidation treatment may be performed at a temperature of about 600 ° C. Even at this temperature, an oxide film can be formed on the core wire 16a.

  When the oxidation treatment is finished, the temperature sensor 1 is manufactured by inserting the thermistor element 12 and the covered electric wire 16 to the protective tube 30 by an appropriate means by inserting into the protective tube 30 from the side where the thermistor element 12 is disposed. Is done.

[effect]
Since the temperature sensor 1 is provided with an air passage in the protective tube 30, oxygen can be supplied to the temperature sensing body 11 through the air passage.
Here, it is necessary to supply oxygen to the temperature sensing element 11 in order to ensure the accuracy of the detection temperature continuously in a high temperature atmosphere. Therefore, if the sensor unit is fixed to the protective tube by a structure in which oxygen is not supplied into the protective tube 30, for example, resin molding, the accuracy of the detected temperature is deteriorated as the usage time elapses. On the other hand, since the temperature sensor 1 is provided with an air passage in the protective tube 30, the accuracy of the detected temperature can be secured for a long time.

  The temperature sensor 1 forms an oxide film on the protective tube 30 and the core wire 16a of the covered electric wire 16 in advance, and oxidizes the insulating coating body 16b and the heat-resistant insulating coating layer 18 of the covered electric wire 16 to cause oxidation. To remove carbon. Therefore, it is possible to prevent the temperature sensing element 11 from being reduced more remarkably.

[Second Embodiment]
Hereinafter, a temperature sensor 2 according to a second embodiment of the present invention will be described with reference to FIGS. 4 to 7, the same elements as those of the temperature sensor 1 are denoted by the same reference numerals as those of the temperature sensor 1.
The temperature sensor 2 is different from the temperature sensor 1 in that the two sensor units 10a and 10b are provided to measure the temperatures of two different measurement points in the high temperature atmosphere. Further, the temperature sensor 2 houses two sensor units 10a and 10b in a single protective tube 30.
The temperature sensor 2 is provided with an air passage for the temperature sensing body 11, the protective tube 30, the core wire 16 a and the insulation coating body 16 b of the covered electric wire 16, and the heat-resistant insulation coating layer 18 are subjected to oxidation treatment, The temperature sensor 1 is followed.

[Sensor units 10a, 10b]
The temperature sensor 2 includes two sensor units 10a and 10b. Each sensor unit 10a, 10b has the same basic configuration as the sensor unit 10 of the first embodiment, but the positions where the temperature sensing elements 11a, 11b are arranged in the protective tube 30 are different. Another difference is that a holder assembly 20 for fixing the two sensor units 10a and 10b is provided. The sensor units 10a and 10b are collectively referred to as the sensor unit 10, and when distinguished from each other, they are referred to as the sensor unit 10a or the sensor unit 10b.
Hereinafter, the difference from the first embodiment will be mainly described with respect to the sensor unit 10a.

As shown in FIGS. 5 and 7, the sensor unit 10 a includes a pair of lead wires 19 connected to each of the pair of covered wires 16, and a holder assembly 20 that holds a connection portion between the covered wires 16 and the lead wires 19. And.
The holder assembly 20 assembles the sensor units 10a and 10b to the protective tube 30 while maintaining the relative positional relationship between the two sensor units 10a and 10b. Further, the holder assembly 20 secures a passage for supplying oxygen from the outside to the temperature sensing bodies 11 of the sensor units 10a and 10b accommodated inside the protective tube 30.

The holder assembly 20 includes two members, a first holder 20a and a second holder 20b shown in FIGS. 5 (c), 5 (d), 6 and 7, and each is integrally formed by injection molding a resin. Are produced.
The 1st holder 20a hold | maintains the sensor unit 10a on both sides of the boundary of the covered electric wire 16 and the lead-out electric wire 19 of the sensor unit 10a. Similarly, the 2nd holder 20b hold | maintains the sensor unit 10b on both sides of the boundary of the covered electric wire 16 and the extraction | drawer electric wire 19 of the sensor unit 10b. Since the basic configurations of the first holder 20a and the second holder 20b are the same, the configuration of the first holder 20a is described based on the first holder 20a, and then the difference between the first holder 20a and the first holder 20a is mentioned. .

As shown in FIG. 6, the first holder 20 a includes a shell 21 that forms an outer shell, a wiring housing chamber 23 that is provided on one side of the front and back of the shell 21, and one end and the other in the axial direction of the shell 21. The front end outlet 27 and the rear end outlet 28 that are provided at each of the end portions and are connected to the wiring housing chamber 23 are provided. The wiring storage chamber 23 includes three elements, a first storage chamber 24, a second storage chamber 25, and a third storage chamber 26, and is arranged in this order from the tip outlet 27 side.
In the holder assembly 20 (the first holder 20a and the second holder 20b), when the sensor unit 10 is assembled, the side where the covered wire 16 is drawn and the thermistor element 12 is disposed is the front, and the drawn wire 19 is The side to be drawn is defined as the back.

When the sensor unit 10a is assembled to the first holder 20a, the electric wires of the sensor unit 10a are accommodated in the respective accommodation chambers as described below. Each accommodation chamber has a volume capable of realizing the following accommodation.
As shown in FIG. 5C, the pair of covered electric wires 16 are accommodated in the first storage chamber 24 so as to be aligned in the width direction W and to have a gap between them. The shell 21 that surrounds the periphery of the first storage chamber 24 has an outer dimension that is narrower than a portion corresponding to the second storage chamber 25, and a front end side that is thinner than the rear. The pair of covered electric wires 16 accommodated in the first accommodating chamber 24 are drawn out from the leading end outlet 27.

As shown in FIG. 5 (c), the connection portion between the covered wire 16 and the lead wire 19 is accommodated in the second storage chamber 25. The second storage chamber 25 is divided into two in the width direction by a partition 22 formed integrally with the shell 21, and a connection portion between one of the covered electric wires 16 and the lead-out electric wire 19 and the other of the pair. A connection part is accommodated in each of the partitioned accommodation chambers.
Each of the covered electric wires 16 and the lead-out electric wires 19 is accommodated in each of the partitioned accommodating chambers, and the connector 14 is disposed on the rear end side of the second accommodating chamber 25, for example, an epoxy adhesive. To the shell 21. In the first storage chamber 24 and the third storage chamber 26, the covered wire 16 and the lead wire 19 are not fixed to the shell 21, but are fixed in the second storage chamber 25. The sensor unit 10a is axially positioned with respect to 20a.

In the third housing chamber 26, the front end side of the lead wire 19 is accommodated, and the rear end side is drawn from the rear end outlet 28.
A lock ridge 29a is formed on the shell 21 surrounding the third storage chamber 26 to engage with the second holder 20b. The locking ridges 29a are formed along the axial direction on both sides of the shell 21 in the width direction.

  The second holder 20b, except that the connector 14 is held on the front end side of the second storage chamber 25 and includes a lock claw 29b corresponding to the lock protrusion 29a of the first holder 20a. The same configuration as the first holder 20a is provided, and the sensor unit 10b is accommodated and held in the same manner as the first holder 20a.

  The first holder 20a that holds the sensor unit 10a and the second holder 20b that holds the sensor unit 10b abut each other and lock the first storage chamber 24, the second storage chamber 25, and the third storage chamber 26 that correspond to each other. The protrusions 29a and the lock claws 29b are engaged with each other to be integrated as shown in FIG. The sensor unit 10 in which the sensor unit 10 a and the sensor unit 10 b are integrated is accommodated in the protective tube 30 in front of the holder assembly 20. Since the distance from the front end of the holder assembly 20 to the thermistor element 12b of the sensor unit 10a is longer than the distance from the thermistor element 12a of the sensor unit 10a, each of the thermistor element 12a and the thermistor element 12b is a protective tube. 30 are arranged at different positions in the axial direction.

  In the first holder 20 a and the second holder 20 b, the wiring housing chamber 23, the leading end outlet 27, and the trailing end outlet 28 have a sufficiently large volume and opening area with respect to the covered wire 16 and the drawn wire 19. Therefore, in the holder assembly 20 in which the first holder 20a and the second holder 20b are assembled, an air passage is formed from the front end outlet 27 to the rear end outlet 28.

The sensor unit 10 having the above configuration is accommodated in the protective tube 30 from the thermistor element 12 to the covered electric wire 16 and is assembled to the protective tube 30.
As shown in FIG. 4, the protective tube 30 is closed at the front end 31 on the side where the thermistor element 12 is disposed, while the rear end 33 is opened, so that the sensor unit 10 housed inside can be vibrated or subjected to external force. A cylindrical member that protects against high heat and combustion gases. The protective tube 30 includes a flange 35 (see FIG. 4) for attaching to the target device on the side close to the rear end 33.

Since the manufacturing procedure of the temperature sensor 2 is the same as that of the temperature sensor 1, the difference will be mainly described below.
Also in the second embodiment, the protective tube 30 and the core wire 16a of the covered electric wire 16 are subject to oxidation treatment. When the oxidation process for the sensor unit 10 is finished, the core wires of the covered wire 16 and the lead wire 19 are overlapped, and the connector 14 is caulked to the overlapped portion, thereby connecting the covered wire 16 and the lead wire 19. To do.

The sensor units 10a and 10b thus manufactured are assembled at predetermined positions of the holders 20a and 20b as shown in FIGS. 5 (c) and 5 (d), respectively. By filling the second storage chamber 25 with an adhesive, the sensor units 10a and 10b are fixed while being positioned at predetermined positions of the holders 20a and 20b, respectively.
Next, the holders 20a and 20b assembled with the sensor units 10a and 10b are arranged so that each wiring accommodation chamber 23 faces each other, and each of the first accommodation chamber 24, the second accommodation chamber 25, and the third accommodation chamber 26 is connected to each other. After alignment, as shown in FIG. Thus, the sensor precursor 100 in which the sensor unit 10 (10a, 10b) is integrated by the holder assembly 20 is obtained.

  Here, the connection portion (connector 14) of the covered electric wire 16 and the lead wire 19 of the sensor unit 10a, and the connection portion (connector 14) of the covered electric wire 16 and the lead wire 19 of the sensor unit 10b are each in the second housing. The arrangement position in the chamber 25 is shifted in the axial direction. Therefore, even if the holders 20a and 20b are assembled, it is possible to avoid electrical contact between the connection portions. In addition, although each connector 14 of the sensor unit 10a and the sensor unit 10b can secure mutual insulation by forming a layer made of an adhesive around the periphery, the position of each connector 14 can be as in this embodiment. By shifting, insulation can be obtained reliably.

If the sensor precursor 100 is obtained, it is inserted into the protective tube 30 from the side where the thermistor element 12 is disposed, and is directed toward the protective tube 30 until the tip of the holder assembly 20 is inserted into the rear end 33 of the protective tube 30. Push in. If the holder assembly 20 is pushed to a predetermined position, the fixing ring 37 is positioned around the holder assembly 20 corresponding to the first storage chamber 24 and then caulked to fit the holder assembly 20. To the protective tube 30.
The temperature sensor 2 is manufactured by the above procedure.

[effect]
The temperature sensor 2 having the above configuration has the following effects.
The temperature sensor 2 is provided with two thermistor elements 12 at different positions inside one protective tube 30. Therefore, compared to housing the two sensor units 10a and 10b in individual protective tubes, the occupied space can be suppressed and the cost can be reduced.

  In addition, the temperature sensor 2 fixes the sensor units 10a and 10b to the corresponding holders 20a and 20b, and then assembles and fixes the holders 20a and 20b. Accordingly, each thermistor element 12 of each sensor unit 10a, 10b can be arranged at a predetermined position of the protective tube 30 without causing a relative displacement, so that two measurement points required in a high temperature atmosphere can be obtained. The temperature can be detected with high accuracy.

  Further, since the temperature sensor 2 is provided with a ventilation path in the holder assembly 20, oxygen can be supplied to the temperature sensing body 11 through the ventilation path and the protective tube 30. Therefore, the temperature sensor 2 can ensure the accuracy of the detected temperature for a long time. Moreover, with respect to the temperature sensor 2, an oxide film is formed in advance on the protective tube 30 and the core wire 16 a of the covered electric wire 16, and an oxidation treatment is performed on the insulating coating body 16 b and the heat-resistant insulating coating layer 18 of the covered electric wire 16. Remove the carbon that causes it. Therefore, it is possible to prevent the temperature sensing element 11 from being reduced more remarkably.

The preferred embodiment of the present invention has been described above. However, the configuration described in the above embodiment can be selected or changed to another configuration as appropriate without departing from the gist of the present invention.
For example, as shown in FIG. 8, the periphery of the thermistor element can be covered with a protective tube 13 made of ceramics. As shown in FIG. 8 (a), the protective tube 13 can have a bottomed shape, and as shown in FIG. 8 (b), the protective tube 13 can have a simple shape without a bottom. it can. Further, as shown in FIG. 8C, only a part of the sealing material 17 can be covered with a ceramic tube.

  Further, the thermistor elements 12 housed in the protective tube 30 are not limited to two, and any number of thermistor elements 12 of three or more can be provided. In this case, the holders are provided according to the number of thermistor elements 12. For example, when three thermistor elements 12 are provided, three holders corresponding to each are provided.

DESCRIPTION OF SYMBOLS 1, 2 Temperature sensor 10, 10a, 10b Sensor unit 11, 11a, 11b Temperature sensing element 12, 12a, 12b Thermistor element 13 Protective tube 14 Junction 15 Lead wire 16 Covered electric wire 16a Core wire 16b Insulation covering 17 Sealing material 18 Heat-resistant insulating coating layer 19 Lead wire 20 Holder assembly 20a First holder 20b Second holder 21 Shell 22 Screen 23 Wiring storage chamber 24 First storage chamber 25 Second storage chamber 26 Third storage chamber 27 Tip outlet 28 Rear end pulling Exit 29a Lock protrusion 29b Lock claw 30 Protective tube 31 Front end 33 Rear end 35 Flange 37 Fixing ring 100 Sensor precursor B Bonding interface O Oxide W Width direction

Claims (5)

A protective tube made of a heat-resistant alloy with the front end side sealed and the rear end side opened,
A sensor unit including a thermistor element housed inside the protective tube, a pair of electric wires electrically connected to the thermistor element, and a heat-resistant insulating coating layer covering the thermistor element;
The protective tube is provided with an air passage that communicates the inside and the outside by opening the rear end side, and an oxide film is formed on the surface in advance,
The thermistor element includes a temperature sensor made of a thermistor, and a lead wire made of a noble metal connected to the temperature sensor through an electrode,
Each of the pair of wires is
A coated wire comprising a core wire made of a heat-resistant alloy connected to the lead wire, and an insulating covering covering the periphery of the core wire,
The core wire of the covered electric wire has an oxide film formed in advance in a region accommodated in the protective tube,
A temperature sensor characterized by that. One or both of the heat-resistant insulating coating layer and the insulating coating body are:
Along with the core wire, the organic component that consumes oxygen by combustion is reduced by being subjected to an oxidation treatment that forms an oxide film on the core wire.
The temperature sensor according to claim 1. The heat-resistant alloy constituting the protective tube and the heat-resistant alloy constituting the core wire of the coated electric wire are made of a matrix-reinforced Ni-base superalloy,
The temperature sensor according to claim 1 or 2. The sensor unit is
A first sensor unit including a first thermistor element housed in the protective tube and having a pair of first electric wires electrically connected to the first thermistor element;
A pair of second electric wires that are accommodated in the protective tube and are electrically connected to the second thermistor element, the second thermistor element being accommodated at a position different from the position where the first thermistor element is accommodated. A second sensor unit comprising:
A first holder for positioning and fixing the first electric wire of the first sensor unit;
A second holder for positioning and fixing the second electric wire of the second sensor unit;
A holder assembly configured by assembling the first holder and the second holder is fitted into the opening on the rear end side of the protective tube,
The temperature sensor as described in any one of Claims 1-3. The holder assembly is
An air passage that communicates the inside and the outside of the protective tube;
The temperature sensor according to claim 4 .

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