JP5260236B2 - Temperature sensor and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the degradation of detection accuracy by suppressing the characteristic change of a thermistor element. <P>SOLUTION: This temperature sensor has the thermistor element connected to metal core wire projected from the tip of a metallic outer cylinder in a sheath member formed by insulating and holding the metal core wire inside the metallic outer cylinder. A region from the thermistor element to the sheath member including at least the tip part of the outer cylinder is held in the internal space of a metallic surrounding member closed at one end and opened at the other end. Oxide films are formed on the surfaces of the surrounding member and sheath member. The hydrogen content of the sheath member is 8 ppm or less, and the hydrogen content of the surrounding member is less than that of the sheath member. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a temperature sensor having a thermistor element and a method for manufacturing the same, and particularly suitable for a temperature sensor used in a high-temperature oxidizing atmosphere, for example, a temperature sensor (exhaust temperature sensor) for detecting the temperature of an exhaust gas of an automobile. Related to a temperature sensor.

  Conventionally, a temperature sensor using a thermistor element whose resistance value changes depending on the temperature is mainly used for detecting a high temperature exceeding 600 ° C., mainly an automobile exhaust gas temperature (hereinafter simply referred to as “exhaust temperature”). It is often used as an application for detecting. As the exhaust temperature of the automobile to be detected, a wide range of detection from a low temperature range of about -40 ° C to a high temperature range of about 900 ° C to 1000 ° C is required.

  A temperature sensor using a thermistor element is generally connected to a thermistor element composed of a thermistor sintered body whose resistance changes with temperature and an electrode wire made of platinum or a platinum alloy, and an electrode wire of the thermistor element. And a sheath member formed by insulatingly holding a pair of lead wires with an insulating powder filled in a cylindrical outer cylinder. The sheath member is housed in a metal tube. Note that the lead wire, outer tube, and metal tube of the sheath member are all made of a stainless alloy. Such a temperature sensor detects the exhaust temperature of an automobile as described above, for example, when it is used in a high temperature atmosphere of about 600 ° C. to 900 ° C., the thermal oxidation of the metal in the metal tube or the sheath member. Oxygen is generated and oxygen inside the metal tube is reduced. At this time, oxygen contained in the thermistor element (specifically, the thermistor sintered body) accommodated in the metal tube is deprived, the thermistor element is reduced, and a characteristic change occurs in the thermistor element. There is a possibility that the detection accuracy as a sensor is lowered.

  Therefore, in order to prevent the above problem, heat treatment is performed on metal parts arranged around the thermistor element such as a sheath member and a metal tube, and an oxide film made of a metal oxide is previously formed on the surface of the metal parts. In addition, it has been proposed to suppress the progress of oxidation of the metal surface during use in a high temperature range (see, for example, Patent Documents 1, 2, and 3).

  Further, the temperature sensor includes a cylindrical member (joint) made of metal that accommodates a rear end side of the sheath member and a lead wire for connecting an external circuit (for example, an ECU of a vehicle).

JP 2004-301679 A Japanese Patent Laid-Open No. 2000-234962 JP-A-6-2014487

  However, even if a temperature sensor that has been treated to prevent reduction of the thermistor element by forming an oxide film on the surface of a metal part such as a metal tube according to the above prior art, sufficient detection accuracy cannot be obtained. was there. Specifically, after the assembly process of the temperature sensor, especially the heat treatment process for filling the metal tube and the thermistor element with an insulating metal oxide (cement) and drying the filled metal oxide, the thermistor. The characteristics of the element fluctuate, and there are individuals that deviate from the specified value and become defective products, and the yield is not good. In addition, there are individuals that cannot withstand use in a high temperature atmosphere of 800 ° C. or higher.

  The present invention has been made to solve the above-described problem, and an object of the present invention is to provide a temperature sensor that can prevent a decrease in detection accuracy by suppressing a change in characteristics of a thermistor element.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

[Application Example 1]
The thermistor element is connected to the metal core wire protruding from the tip of the outer cylinder in the sheath member formed by insulatingly holding the metal core wire inside the metal outer cylinder, one end is closed and the other end is opened In the temperature sensor in which the space from the thermistor element to the region of the sheath member including at least the tip of the outer cylinder is accommodated in the internal space of the metal surrounding member,
An oxide film is formed on the surfaces of the surrounding member and the sheath member, the hydrogen content of the sheath member is 8 ppm or less, and the hydrogen content of the surrounding member is higher than the hydrogen content of the sheath member. A temperature sensor characterized by being small.

  In the temperature sensor described in Application Example 1, an oxide film is formed on the surfaces of the surrounding member and the sheath member, the hydrogen content of the sheath member is 8 ppm or less, and the hydrogen content of the surrounding member is equal to that of the sheath member. Less than hydrogen content. Thereby, even if this temperature sensor is used in a high temperature region, generation of desorbed hydrogen is suppressed. As a result, it is possible to prevent a decrease in detection accuracy by suppressing the characteristic change of the thermistor element.

[Application Example 2]
In the temperature sensor described in Application Example 1,
The temperature sensor characterized by the hydrogen content of the surrounding member being 6 ppm or less.

  In the temperature sensor described in Application Example 2, since the hydrogen content of the surrounding member is 6 ppm or less, which is smaller than 8 ppm of the hydrogen content of the sheath member, even if this temperature sensor is used in a high temperature range, the desorbed hydrogen. Is suppressed. As a result, it is possible to prevent a decrease in detection accuracy by suppressing the characteristic change of the thermistor element.

[Application Example 3]
In the temperature sensor described in Application Example 1,
The temperature sensor characterized by the hydrogen content of the surrounding member being 5 ppm or less.

  In the temperature sensor described in Application Example 3, since the hydrogen content of the surrounding member is 5 ppm or less, which is smaller than 8 ppm of the hydrogen content of the sheath member, even if this temperature sensor is used in a high temperature range, the desorbed hydrogen. Is suppressed. As a result, it is possible to prevent a decrease in detection accuracy by suppressing the characteristic change of the thermistor element.

[Application Example 4]
In the temperature sensor according to any one of Application Examples 1 to 3,
A surrounding member that surrounds the outer peripheral surface of the surrounding member, and a mounting member for mounting the temperature sensor on a mounting target body;
A tubular member that surrounds the rear end side of the sheath member protruding from the other end of the surrounding member, and is fixed to the attachment member;
The temperature sensor characterized by the hydrogen content of the said cylindrical member being 4 ppm or less.

  In the temperature sensor described in Application Example 4, the hydrogen content of the cylindrical member is 4 ppm or less. Therefore, even if the temperature sensor to which the cylindrical member for surrounding the rear end side of the sheath member is fixed to the attachment member surrounding the surrounding member is used in the high temperature range, the generation of desorbed hydrogen can be suppressed. As a result, the amount of desorbed hydrogen from the cylindrical member that reaches the thermistor element through the space between the surrounding member and the sheath member (specifically, the outer cylinder of the sheath member) can be suppressed, and the temperature sensor having the above structure Even in the case of adopting, it is possible to further suppress the change in the characteristics of the thermistor element and prevent the detection accuracy from being lowered.

[Application Example 5]
The thermistor element is connected to the metal core wire protruding from the tip of the outer cylinder in the sheath member formed by insulatingly holding the metal core wire inside the metal outer cylinder, one end is closed and the other end is opened In the manufacturing method of the temperature sensor in which the space from the thermistor element to the region of the sheath member including at least the distal end portion of the outer cylinder is accommodated in the internal space of the metal surrounding member that is,
A wet hydrogen atmosphere oxidation treatment step of performing heat treatment on the surrounding member and the sheath member in a wet hydrogen atmosphere to oxidize the metal surfaces of the surrounding member and the sheath member;
The enclosure member and the sheath member that have undergone the oxidation treatment step in the wet hydrogen atmosphere are subjected to heat treatment in an atmosphere that does not contain hydrogen to desorb hydrogen contained in the enclosure member and the sheath member. A hydrogen desorption treatment step,
A method for manufacturing a temperature sensor, comprising:

[Application Example 6]
In the manufacturing method of the temperature sensor according to Application Example 5,
Prior to the oxidizing treatment step in the wet hydrogen atmosphere, the surrounding member and the sheath member are heat-treated in an air atmosphere to oxidize the metal surfaces of the surrounding member and the sheath member. A method of manufacturing a temperature sensor, comprising a step.

  According to the manufacturing method of the temperature sensor described in Application Example 5 and Application Example 6, hydrogen is desorbed from the surrounding member and the sheath member in the space in which the thermistor element is accommodated, and the thermistor element is reduced. As a result, it is possible to manufacture a temperature sensor that suppresses a decrease in detection accuracy.

[Application Example 7]
In the temperature sensor manufacturing method according to Application Example 5 or Application Example 6,
In the hydrogen desorption treatment step, the hydrogen content of the sheath member is desorbed to 8 ppm or less, and the hydrogen content of the surrounding member is desorbed so as to be smaller than the hydrogen content of the sheath member. A method for manufacturing a temperature sensor.

  According to the manufacturing method of the temperature sensor described in Application Example 7, the temperature sensor described in Application Example 1 can be manufactured.

[Application Example 8]
In the manufacturing method of the temperature sensor of the application example 7, In the said content hydrogen desorption process process, the hydrogen content of the said surrounding member is desorbed to 6 ppm or less, The manufacturing method of the temperature sensor characterized by the above-mentioned.

  According to the temperature sensor manufacturing method described in Application Example 8, the temperature sensor described in Application Example 2 can be manufactured.

[Application Example 9]
In the manufacturing method of the temperature sensor according to Application Example 7,
In the said hydrogen desorption process, the hydrogen content of the said surrounding member is desorbed to 5 ppm or less, The manufacturing method of the temperature sensor characterized by the above-mentioned.

  According to the temperature sensor manufacturing method described in Application Example 9, the temperature sensor described in Application Example 3 can be manufactured.

[Application Example 10]
In the manufacturing method of the temperature sensor according to any one of Application Example 5 to Application Example 9,
A surrounding member that surrounds the outer peripheral surface of the surrounding member, and a mounting member for mounting the temperature sensor on a mounting target body;
A tubular member that surrounds the rear end side of the sheath member protruding from the other end of the surrounding member, and is fixed to the attachment member;
A hydrogen desorption step of desorbing hydrogen contained in the cylindrical member by performing a heat treatment in an atmosphere not containing hydrogen on the cylindrical member;
A method for manufacturing a temperature sensor, further comprising:

  According to the manufacturing method of the temperature sensor described in Application Example 10, the amount of desorbed hydrogen generated in the cylindrical member can be suppressed. As a result, the amount of desorbed hydrogen of the tubular member that reaches the thermistor element through the space between the surrounding member and the sheath member (specifically, the outer tube of the sheath member) can be suppressed. Even when the configuration of the temperature sensor is adopted, it is possible to further suppress the characteristic change of the thermistor element and prevent the detection accuracy from being lowered.

[Application Example 11]
In the manufacturing method of the temperature sensor according to Application Example 10,
In the hydrogen desorption process, hydrogen is desorbed so that the hydrogen content of the cylindrical member is 4 ppm or less.

  According to the temperature sensor manufacturing method of Application Example 11, the temperature sensor described in Application Example 4 can be manufactured.

  Here, “ppm” is a unit indicating the proportion of how much is one millionth, and represents a weight ratio. In the present application, it means a value obtained by dividing the weight of the hydrogen content by the weight of the original member containing hydrogen. For example, “the hydrogen content of the surrounding member is 6 ppm” described in the application example 8 means that 1 mg of the surrounding member contains 6 mg of hydrogen.

Hereinafter, embodiments of the present invention will be described in the following order based on examples.
A. First embodiment:
A1. Temperature sensor structure:
A2. Temperature sensor manufacturing process:
A3. Baking effect:
A4. Effect of fifth heat treatment step on cylindrical member:
B. Second embodiment:
C. Variations:

A. First embodiment:
A1. Temperature sensor structure:
FIG. 1 is a partially broken sectional view showing a structure of a temperature sensor as a first embodiment of the present invention. The temperature sensor 1 uses a thermistor element 2 as a temperature sensitive element. For example, by mounting the temperature sensor 1 on an exhaust pipe of an automobile that is a mounting target body, the metal tube 3 that is a metal surrounding member including the thermistor element 2 is disposed in the exhaust pipe through which exhaust gas flows, It can be used for temperature detection of exhaust gas. The thermistor element 2 has a disc-like thermistor sintered body made of a perovskite oxide and a pair of electrode wires (Pt / Rh alloy wire 9) partially embedded in the thermistor sintered body. It has a known configuration.

The metal tube 3 extending in the direction of the axis of the temperature sensor 1 (indicated by the alternate long and short dash line) is formed in a cylindrical shape with the distal end portion 31 closed, and the thermistor element 2 is accommodated in the distal end portion 31. The metal tube 3 is formed of a stainless alloy as will be described later. The cement tube 10 is filled inside the metal tube 3 and around the thermistor element 2, thereby preventing the thermistor element 2 from swinging due to vibration during use. The rear end portion 32 side of the metal tube 3 is open, and the rear end portion 32 is inserted inside the stainless steel flange 4. The cement 10 is composed of an aggregate mainly composed of alumina powder and a glass component containing SiO ₂ or silica.

  The flange (attachment member) 4 includes a sheath portion 42 that extends in the axial direction, and a projecting portion 41 that is located on the distal end side of the sheath portion 42 and projects outward in the radial direction. The protruding portion 41 is formed in an annular shape having a tapered seating surface 45 corresponding to the tapered portion of the mounting portion of the exhaust pipe (mounting object) (not shown) on the distal end side, and the seating surface 45 is a taper of the mounting portion. The exhaust gas is prevented from leaking outside the exhaust pipe by being in close contact with the portion. The sheath portion 42 is formed in a ring shape, and has a two-stage shape including a front end side step portion 44 located on the front end side and a rear end side step portion 43 having an outer diameter smaller than that of the front end side step portion 44. ing.

  The metal tube 3 is inserted from the rear end portion 32 of the metal tube 3 to the front end side of the protruding portion 41 of the flange 4 and is press-fitted inside the sheath portion 42. And the part which the outer peripheral surface of the metal tube 3 and the inner peripheral surface of the rear-end side step part 43 of the sheath part 42 overlap is laser-welded over the circumferential direction. By performing this laser welding, as shown in FIG. 1, a welded portion L <b> 1 is formed across the rear end side stepped portion 43 of the sheath portion 42 and the metal tube 3, and the metal tube 3 is fixed to the flange 4. Is done.

  A tubular joint (tubular member) 6 is joined to the radially outer side of the front end side step portion 44 of the sheath portion 42 of the flange 4. Specifically, the joint 6 is press-fitted into the distal end side step portion 44 of the sheath portion 42 such that the inner peripheral surface of the joint 6 overlaps the outer peripheral surface of the distal end side step portion 44 of the sheath portion 42, and the joint 6 and the distal end The side step portion 44 is laser welded in the circumferential direction. By performing this laser welding, as shown in FIG. 1, a welded portion L <b> 2 straddling the distal end side stepped portion 44 of the sheath portion 42 and the joint 6 is formed.

  By forming a welded portion L1 straddling the rear end side stepped portion 43 of the sheath portion 42 and the metal tube 3 and a welded portion L2 straddling the front end side stepped portion 44 of the sheath portion 42 and the tubular member 6, the surrounding member 3 and the cylindrical member 6 are connected to the attachment member 4, respectively. In other words, the surrounding member 3 and the cylindrical member 6 are connected via the attachment member 4. Here, the joint 6 and the cylindrical member 6 are synonymous, and the attachment member 4 and the flange 4 are synonymous.

Inside the metal tube 3, the flange 4, and the joint 6, a sheath member 8 formed by insulatingly holding a pair of metal core wires 7 inside a cylindrical outer cylinder 21 is disposed. Inside the metal tube 3, the thermistor element 2 connects the Pt / Rh alloy wire 9 constituting the electrode wire of the thermistor element 2 to the tip of the metal core wire 7 protruding from the tip of the outer cylinder 21 of the sheath member 8. Connected through. The alloy wire 9 and the metal core wire 7 are laser-welded or resistance-welded to each other. The sheath member 8 is not shown in detail, but a metal outer tube 21 made of a stainless alloy (for example, SUS310S), a pair of metal core wires 7 made of a stainless alloy (for example, SUS310S), the outer tube, It is composed of an insulating powder mainly composed of SiO ₂ that insulates the metal core wire 7 and holds the metal core wire 7.

  The metal core wire 7 protruding from the rear end to the rear end side of the outer cylinder 21 of the sheath member 8 inside the joint 6 is laser-welded or resistance-welded to the crimp terminal 11, and a pair of external circuits (for example, via the crimp terminal 11) Connected to a lead wire 12 for connection. The pair of metal core wires 7 and the pair of crimp terminals 11 are insulated from each other by an insulating tube 15. The lead wire 12 is formed by coating a metal stranded wire with an insulating covering material, and is inserted into an auxiliary ring 13 made of heat-resistant rubber provided in the opening on the rear end side of the joint 6. And the auxiliary | assistant ring 13 is mutually fixed, maintaining the airtightness by the auxiliary | assistant ring 13 and the coupling 6 by carrying out the round crimping or the polygonal crimping from the top of the coupling 6. FIG. Thereby, the thermistor element 2 is accommodated in the sealed space formed by the metal tube 3, the flange 4 and the joint 6. The output of the thermistor element 2 is taken out from the metal core wire 7 of the sheath member 8 to the external circuit (not shown) through the lead wire 12, and the temperature of the exhaust gas is detected.

  Since the temperature sensor 1 is used in a high temperature environment as high as 1000 ° C., each component member needs to have sufficient heat resistance. Therefore, the metal tube 3, the flange 4, the outer cylinder 21, and the metal core wire 7 are mainly composed of Fe, and contain C, Si, Mn, P, S, Ni, and Cr at 24.00 to 26.00% by weight. It is formed of SUS310S which is a heat resistant alloy. Further, the joint 6 is SUS304 (a heat-resistant alloy containing C, Si, Mn, P, S, Ni, and Cr in addition to Fe and containing Cr at 18.00 to 20.00% by weight). Is the material.

A2. Temperature sensor manufacturing process:
The temperature sensor 1 is manufactured through the following steps.

  First, the metal tube 3 and the flange 4 using SUS310S as a heat resistant alloy as a material are formed in advance. In addition, the sheath member 8 is formed in advance using the outer cylinder 21, the metal core wire 7, and the insulating powder using SUS310S as a heat-resistant alloy as a material. Furthermore, the other components 2, 6, 10 to 13 are also formed in advance.

  Next, the metal tube 3, the sheath member 8, and the flange 4 are subjected to a heat treatment (oxidation treatment) for forming an oxide film by a first heat treatment step and a second heat treatment step described later. Further, the metal tube 3, the flange 4, and the sheath member 8 (specifically, the outer cylinder 21 and the metal core wire 7) on which the oxide film is formed are subjected to heat treatment for desorption of hydrogen contained in a third heat treatment step to be described later. (Baking treatment) is performed.

  Then, the members 3, 4 and 8 on which the oxide film is formed and the contained hydrogen are desorbed and the other components 2, 6, 11 to 13 are assembled to each other to manufacture the temperature sensor 1 shown in FIG. Complete. Before inserting the assembly of the thermistor element 2 and the sheath member 8 into the metal tube 3, the uncured cement 10 is filled into the metal tube 3, and the assembly is inserted into the metal tube 3 after filling. The cement 10 was hardened by passing through a drying process.

  In addition, a cylindrical member (joint) 6 using SUS304 as a material is provided with a fourth heat treatment step (annealing step) described later and a fifth heat treatment step for removing hydrogen contained (baking treatment, hydrogen desorption treatment). 1 is completed, after the fifth heat treatment step is performed on the cylindrical member 6, the flange 4 and other parts are assembled to each other to complete the manufacture of the temperature sensor 1 shown in FIG.

  FIG. 2 is a process diagram showing a heat treatment process part in the manufacturing process of the temperature sensor.

  First, as a first heat treatment step, the metal tube 3, the flange 4 and the sheath member 8 are subjected to a high-temperature heat treatment (oxidation treatment in an air atmosphere) at a treatment temperature of 1000 ° C. and a treatment time of 10 hours in an air atmosphere. In addition, about the metal tube 3 and the flange 4, the 1st heat processing process and the 2nd heat processing process mentioned later are implemented in the state which press-fixed the metal tube 3 inside the flange 4. FIG.

  In the first heat treatment step, the metal tube 3, the flange 4, and the sheath member 8 (specifically, the outer cylinder 21 and the metal core wire 7) are subjected to heat treatment for a long time in an easily controlled air atmosphere. A discontinuous but relatively thick oxide film can be formed on the metal surface.

  Next, as a second heat treatment step, a wet gas made of hydrogen gas containing water through water kept at 35 ° C. and a dry gas made of dry hydrogen are introduced into the treatment furnace at a ratio of 1: 2.2. Then, the members 3, 4, and 8 on which the oxide film was formed in the first heat treatment step are accommodated in the processing furnace, and the processing temperature is 1150 ° C. and the processing time in a wet hydrogen atmosphere (wet hydrogen atmosphere). A high-temperature heat treatment (acid treatment in a wet hydrogen atmosphere) is performed in 1 hour.

  In the second heat treatment step, at least the missing portion of the oxide film formed in the first heat treatment step (in other words, the surface on which the oxide film was not formed) among the surfaces of the members 3, 4, 8. An oxide film in which chromium oxide is selectively generated is formed.

  Further, as the third heat treatment step, the members 3, 4, and 8 on which the oxide film is formed in the second heat treatment step are subjected to low-temperature heat treatment at a treatment temperature of 700 ° C. and a treatment time of 30 minutes in an air atmosphere ( Bake treatment and hydrogen desorption treatment).

  In the third heat treatment step, hydrogen contained in the members 3, 4, and 8 is desorbed, and the hydrogen content of the members 3, 4, and 8 is reduced.

FIG. 10 is a process diagram showing a heat treatment process part of the tubular member 6 and a diagram showing heat treatment conditions of the fifth heat treatment process. First, as a fourth heat treatment step, the cylindrical member 6 is annealed in a hydrogen atmosphere at a treatment temperature of 1100 ° C. and a treatment time of 2 hours. Thereby, the internal stress after processing of the cylindrical member 6 can be removed.

  Next, as a fifth heat treatment step, the tubular member 6 subjected to the annealing treatment was subjected to No. 1 shown in FIG. 1-No. Heat treatment (baking treatment, containing hydrogen desorption treatment) is performed under the conditions of 8 respectively. Thereby, the hydrogen contained in the cylindrical member 6 is desorbed, and the hydrogen content of the cylindrical member 6 is reduced. Here, the heating temperature in the fifth heat treatment step is preferably in the range of 200 ° C to 400 ° C. The lower limit was set to 200 ° C. because the desorption of the hydrogen contained in the cylindrical member 6 before the fifth heat treatment step described later starts from around 200 ° C. (see FIGS. 18 and 19). This is because 200 ° C. or higher is suitable for desorption. Further, the upper limit is set to 400 ° C., when heat treatment at a high temperature is performed, an oxide film may be formed on the entire surface of the cylindrical member 6, and the cylindrical member 6 and other members (for example, the attachment member 4). This is because it is necessary to remove the oxide film when welding.

A3. Baking effect:
The effect of the baking process by the third heat treatment step will be described.

  The second heat treatment step is performed in a wet hydrogen atmosphere. In addition, the metal tube 3 and the sheath member 8 generally include a heat treatment process called “annealing” in order to relieve stress during processing in the manufacturing process. This annealing step is generally performed in a non-oxygen-containing atmosphere, for example, a hydrogen-containing atmosphere in order to prevent oxidation. Therefore, in the second heat treatment step or annealing step performed in a hydrogen atmosphere, the metal tube 3 and the sheath member 8 contain hydrogen by adsorption, solid solution, etc., and the hydrogen content increases.

  If the hydrogen contained in the metal tube 3 and the sheath member 8 is desorbed from the metal tube 3 and the sheath member 8 when the temperature sensor 1 is used, the thermistor element 2 is reduced and the characteristics of the thermistor element are changed. Invite.

  FIG. 3 is a graph showing the results of analyzing the relationship between the ambient temperature and desorbed hydrogen for the metal tubes subjected to the first and second heat treatments. Similarly, FIG. 4 is a graph showing the results of analyzing the relationship between the ambient temperature and the desorbed hydrogen for the sheath members subjected to the first and second heat treatments. 3 and 4 show the amount of hydrogen dH / dt [ppm / min] generated per unit time and the cumulative integrated value [ppm] when the ambient temperature is increased in order at a constant rate. ing. The amount of hydrogen contained in the component can be measured, for example, by connecting an atmospheric pressure ionization mass spectrometer (API-MS) as a detector to a temperature programmed desorption apparatus (TPD).

  As shown in FIGS. 3 and 4, hydrogen desorption begins to occur from a temperature around 200 ° C. in both the metal tube and the sheath member. The cumulative integral value of desorbed hydrogen when the temperature rises to 900 ° C. is about 10.4 ppm for the metal tube and about 10.7 ppm for the sheath member. Note that the results of FIGS. 3 and 4 show representative values among the analysis results of a plurality of samples.

  FIG. 11 shows the relationship between the ambient temperature and the amount of hydrogen generated per unit time dH / dt [ppm / min] for a plurality of (four samples) metal tubes 3 subjected to the first and second heat treatments. It is a graph to show. Here, the ambient temperature was increased in order at a constant rate. A sample indicated by a bold solid line (a sample having the highest amount of hydrogen per unit time at 600 ° C.) is the same as the sample shown in FIG.

  FIG. 12 is a graph showing the relationship between the ambient temperature and the accumulated value [ppm] of desorbed hydrogen for a plurality of (four samples) metal tubes 3 subjected to the first and second heat treatments. The accumulated value of desorbed hydrogen is calculated based on the amount of hydrogen per unit time in FIG. According to this, it can be seen that the cumulative value of desorbed hydrogen when the temperature rises to 900 ° C. is at least 9.3 ppm. A sample in which the cumulative value of desorbed hydrogen is about 10.4 ppm is the same as the sample shown in FIG.

  FIG. 13 shows the relationship between the ambient temperature and the amount of hydrogen generated per unit time dH / dt [ppm / min] for a plurality of sheath members 8 (four samples) subjected to the first and second heat treatments. It is a graph to show. Here, the ambient temperature was increased in order at a constant rate. According to this, it can be seen that any sheath member 8 begins to desorb hydrogen from around 200 ° C. A sample indicated by a bold solid line (a sample having the highest hydrogen content at about 450 ° C.) is the same as the sample shown in FIG.

  FIG. 14 is a graph showing the relationship between the ambient temperature and the accumulated value [ppm] of desorbed hydrogen for a plurality of sheath members 8 (three samples) subjected to the first and second heat treatments. The accumulated value of desorbed hydrogen is calculated based on the amount of hydrogen per unit time in FIG. According to this, it can be seen that the cumulative value of desorbed hydrogen when the temperature rises to 900 ° C. is at least about 10.2 ppm or more. Note that the sample in which the cumulative value of desorbed hydrogen is about 10.7 ppm is the same as the sample shown in FIG.

  From the above, it is considered that when the temperature sensor using these members is used at a high temperature, the hydrogen desorbed from the metal tube 3 and the sheath member 8 causes the characteristics of the thermistor element 2 to change.

  Therefore, in order to prevent the characteristic change of the thermistor element 2 due to the hydrogen desorbed from the metal tube 3 or the sheath member 8, hydrogen contained in the metal tube 3 or the sheath member 8 is desorbed in advance. It is preferable to perform a baking process by a third heat treatment step.

  FIG. 5 is a graph showing the result of analyzing the relationship between the ambient temperature and desorbed hydrogen for a metal tube that has been baked. Similarly, FIG. 6 is a graph showing the results of analyzing the relationship between the ambient temperature and the desorbed hydrogen for the sheath member subjected to the baking treatment. 5 and 6 also show the amount of hydrogen dH / dt [ppm / min] generated per unit time when the ambient temperature is increased in order at a constant rate, as in FIGS. The cumulative integral value [ppm] is shown.

  As shown in FIG. 5, in the metal tube 3 that has been subjected to the baking treatment, the cumulative integral value of desorbed hydrogen when the atmospheric temperature is raised to 900 ° C. is about 4.3 ppm, and the metal tube that is not subjected to the baking treatment It can be seen that the cumulative integrated value in the case of 3 is about 10.4 ppm (see FIG. 3), but is reduced to ½ or less. Further, as shown in FIG. 6, in the sheath member 8 that has been subjected to the baking process, the cumulative integral value of desorbed hydrogen when the ambient temperature is raised to 900 ° C. is about 7.4 ppm, and the baking process is not performed. It can be seen that the cumulative integral value in the case of the sheath member 8 is 10.7 ppm (see FIG. 4), but is reduced to 3/4 or less. Note that the results of FIGS. 5 and 6 show representative values among the analysis results of a plurality of samples.

  FIG. 15 is a graph showing the relationship between the atmospheric temperature and the amount of hydrogen generated per unit time dH / dt [ppm / min] for a plurality (12 samples) of the metal tube 3 subjected to the baking treatment. The ambient temperature was increased at a constant rate. According to this, in the metal tube 3 where the baking process is not performed, the maximum amount of hydrogen per unit time was recorded in the range of about 500 ° C. to about 650 ° C. (see FIG. 11), but the baking process was performed. It can be seen that in the metal tube 3, the maximum value of the hydrogen amount per unit time tends to shift to a higher temperature side (for example, 700 ° C. or higher).

  FIG. 16 is a graph showing the relationship between the ambient temperature and the accumulated value [ppm] of desorbed hydrogen for a plurality (12 samples) of the metal tubes 3 subjected to the baking treatment. The accumulated value of desorbed hydrogen is calculated based on the amount of hydrogen per unit time in FIG. According to this, the cumulative value of desorbed hydrogen of the metal tube 3 when the atmospheric temperature is raised to 900 ° C. is 5.4 ppm at the maximum. Therefore, since the cumulative value of desorbed hydrogen in the metal tube 3 that is not subjected to the baking treatment is at least 9.3 ppm or more (see FIG. 12), the hydrogen content of the metal tube 3 is reduced to 3 / by performing the baking treatment. It turns out that it can reduce to 5 or less. In addition, the sample in which the cumulative value is 4.3 ppm is the same as the sample in FIG.

  FIG. 17 is a graph showing the relationship between the ambient temperature and the hydrogen amount dH / dt [ppm / min] generated per unit time for a plurality of sheath members 8 (11 samples) subjected to the baking process. FIG. 18 is a graph showing the relationship between the ambient temperature and the cumulative value [ppm] of desorbed hydrogen for a plurality (11 samples) of the sheath members 8 that have been baked. Note that the cumulative value of desorbed hydrogen is calculated based on the amount of hydrogen per unit time in FIG.

  According to FIGS. 17 and 18, the cumulative value of desorbed hydrogen of the sheath member 8 when the ambient temperature is raised to 900 ° C. is 7.4 ppm at the maximum. Therefore, since the cumulative value of desorbed hydrogen of the sheath member 8 that is not subjected to the baking process is at least 10.2 ppm or more (see FIG. 14), the hydrogen content of the sheath member 3 is reduced to 3 / by performing the baking process. It turns out that it can reduce to 4 or less.

  FIG. 7 is a graph showing a variation in resistance value of a temperature sensor manufactured using a metal tube, a flange, and a sheath member that have been baked. FIG. 8 is a graph showing variations in resistance values of a temperature sensor manufactured using a metal tube, a flange, and a sheath member that are not subjected to baking as a comparative example. In both cases, the number of samples is 150.

  As can be seen from a comparison between FIG. 7 and FIG. 8, the temperature sensor using the parts not subjected to baking is σ = 0.0181, whereas the temperature sensor using the parts subjected to baking is Σ = 0.014, it can be seen that the variation in resistance value is greatly improved.

  Therefore, by baking the metal tube and the sheath member, it is possible to suppress the change in the characteristics of the thermistor element and to reduce the variation in the resistance value. Thus, it is possible to provide a temperature sensor that can suppress the decrease in detection accuracy by suppressing the above.

  The upper limit of the hydrogen content of the metal tube 3 and the sheath member 8 after the baking treatment is 6 ppm or less in consideration of the results of FIGS. 5 and 6 and further the results of FIGS. The sheath member 8 can be set to 8 ppm or less, more preferably 7.5 ppm or less, and even more preferably 6.0 ppm or less.

A4. Effect of the fifth heat treatment step on the cylindrical member 6:
The cylindrical member 6 generally includes a fourth heat treatment step called “annealing” in order to relieve stress during processing in the manufacturing process. This fourth heat treatment step is generally performed in a non-oxygen-containing atmosphere, for example, a hydrogen atmosphere in order to prevent oxidation. In the case of this example, the fourth heat treatment step (annealing treatment) is performed in a hydrogen atmosphere at a treatment temperature of 1100 ° C. and a treatment time of 2 hours. Therefore, in the fourth heat treatment step, the cylindrical member 6 contains hydrogen by adsorption, solid solution, etc., and the hydrogen content increases.

  Here, as shown in FIG. 1, a temperature sensor having a configuration in which a tubular member (joint) 6 for surrounding the rear end side of the sheath member 8 is fixed to an attachment member 4 surrounding the surrounding member 3. 1, when the contained hydrogen is desorbed from the cylindrical member 6 when the temperature sensor 1 is used, the desorbed hydrogen reaches the thermistor element 2 through the space between the surrounding member 3 and the sheath member 8. As a result, the thermistor element 2 may be reduced, resulting in a change in the characteristics of the thermistor element 2.

  FIG. 19 shows the relationship between the ambient temperature and the amount of hydrogen generated per unit time dH / dt [ppm / min] for a plurality (three samples) of cylindrical members 6 subjected to the fourth heat treatment step. It is a graph. The ambient temperature was increased in order at a constant rate. According to this, it can be understood that any cylindrical member 6 begins to desorb hydrogen from around 200 ° C.

  FIG. 20 is a graph showing the relationship between the ambient temperature and the cumulative value [ppm] of desorbed hydrogen for a plurality of (three samples) cylindrical members 6 that have undergone the fourth heat treatment step. The accumulated value of desorbed hydrogen is calculated based on the amount of hydrogen per unit time in FIG. According to this, it can be seen that the cumulative value of desorbed hydrogen when the temperature rises to 900 ° C. is at least 5.4 ppm or more.

  From the above, when the temperature sensor 1 using the cylindrical member 6 on which the fourth heat treatment step has been performed is used at a high temperature (for example, 600 ° C. or higher), hydrogen desorbed from the cylindrical member 6 is removed from the thermistor element. It is considered that the second characteristic change is caused.

  Therefore, in order to prevent a change in the characteristics of the thermistor element 2 due to hydrogen desorbed from the cylindrical member 6, it is preferable to desorb hydrogen contained in the cylindrical member 6 in advance. Therefore, the fifth heat treatment step is performed.

  FIG. 21 is a graph showing the relationship between the atmospheric temperature and the hydrogen content dH / dt [ppm / min] generated per unit time for the cylindrical member 6 on which the fifth heat treatment step has been performed. FIG. 22 is a graph showing the relationship between the ambient temperature of the cylindrical member 6 that has undergone the fifth heat treatment step and the cumulative value [ppm] of desorbed hydrogen. Here, the cumulative value of desorbed hydrogen is calculated based on the amount of hydrogen per unit time in FIG. Moreover, the cylindrical member 6 which respectively performed the 5th heat processing process on the process conditions shown in FIG.22 (b) was used for the measurement.

  As shown in FIG. 22 (a), in the cylindrical member 6 subjected to the fifth heat treatment step, the cumulative value of desorbed hydrogen when the ambient temperature is raised to 900 ° C. is 3.0 ppm at the maximum. . Therefore, since the cumulative value of desorbed hydrogen of the cylindrical member 6 that does not perform the fifth heat treatment step is at least 5.4 ppm or more (see FIG. 20), the cylindrical member can be obtained by performing the fifth heat treatment step. It can be seen that the hydrogen content of 6 can be reduced to 3/5 or less. Moreover, it turns out that the hydrogen content of the cylindrical member 6 can be 2/5 or less depending on the fifth heat treatment condition. For example, in the cylindrical member 6 that has been subjected to the fifth heat treatment step at a treatment temperature of 400 ° C. and a heat treatment time of 40 hours, the accumulated value of desorbed hydrogen is 1.4 ppm, and hydrogen is obtained by performing the fifth heat treatment step. The content can be reduced to 3/10 or less.

  FIG. 23 is a graph showing repeated temperature changes of a temperature sensor 1 (hereinafter, referred to as “pre-treatment temperature sensor 1”) manufactured using a cylindrical member 6 that does not perform the fifth heat treatment step. As a test method, the temperature sensor 1 is heated to 100 ° C. to 900 ° C., and the resistance value is measured for each temperature (first test). Next, the temperature sensor 1 is cooled to 100 ° C., the same temperature sensor 1 is heated again to 100 ° C. to 900 ° C., and the resistance value for each temperature is measured (second test). The resistance value obtained in the first test is 0, and the resistance value obtained in the second test is compared with the resistance value obtained in the first test. The deviation was converted into temperature and plotted. The number of samples is 50, and any of the temperature sensors 1 is baked on the metal tube 3, the flange 4 and the sheath member 8.

  FIG. 24 is a graph showing repeated temperature changes of the temperature sensor 1 (hereinafter referred to as “post-treatment temperature sensor 1”) manufactured using the cylindrical member 6 that has been subjected to the fifth heat treatment step (baking treatment). . The test method and the number of samples are the same as in the test of FIG. In any of the temperature sensors 1, the metal tube 3, the flange 4 and the sheath member 8 are baked.

  Comparing FIG. 23 and FIG. 24, it can be seen that the variation in resistance value of the post-treatment temperature sensor 1 is significantly improved as compared to the pre-treatment temperature sensor 1. In other words, the post-treatment temperature sensor 1 desorbs the hydrogen contained in the cylindrical member 6 in advance by the fifth heat treatment step. Therefore, the amount of hydrogen desorbed from the cylindrical member 6 of the post-treatment temperature sensor 1 during the first test is lower than the amount of hydrogen desorbed from the cylindrical member 6 of the pre-treatment temperature sensor 1. Therefore, the characteristic change of the thermistor element 2 can be prevented, and the fluctuation of the resistance value can be greatly improved.

  Further, the upper limit value of the hydrogen content of the cylindrical member 6 subjected to the fifth heat treatment step is 4 ppm or less, preferably 3 ppm or less, more preferably 2.5 ppm or less in consideration of the results of FIGS. 21 and 22. Can be set.

  The cylindrical member 6 is located farther from the thermistor element 2 than the surrounding member 3 and the sheath member 8, but the upper limit value of the hydrogen content of the cylindrical member 6 is the hydrogen content of the surrounding member 3 and the sheath member 8. It is preferable to set the amount lower than the upper limit value. This is because the cylindrical member 6 is generally heavier than the surrounding member 3 and the sheath member 8, so that if the hydrogen content [ppm] is high, the amount of hydrogen generated from the entire cylindrical member 6 is This is because even if the position is higher than that of the sheath member 8 and away from the thermistor element 2, there is a possibility of affecting the characteristic change.

B. Second embodiment:
FIG. 9 is a partially broken sectional view showing the structure of a temperature sensor as a second embodiment of the present invention. Compared with the temperature sensor 1 of the first embodiment, the temperature sensor 100 is mainly different in a member for housing the thermistor element 2 and a member to be laser-welded to the sheath portion of the flange. The part is almost the same. Accordingly, the description will focus on the parts different from the first embodiment, and the description of the same parts will be omitted or simplified.

  In the temperature sensor 1 of the first embodiment, the thermistor element 2 is accommodated inside the metal tube 3, and the metal tube 3 is fixed to the flange 4 by laser welding (see FIG. 1). On the other hand, in the temperature sensor 100 of the present embodiment shown in FIG. 9, the thermistor element 2 is accommodated in a metal cap 14 as a metal surrounding member, and this metal cap 14 is welded to the sheath member 8 (specifically, , Laser welding), the sheath member 8 is fixed to the flange 4 by laser welding.

  The metal cap 14 extending in the axial direction has a cylindrical shape with the distal end 131 side closed, and the thermistor element 2 is accommodated inside the distal end 131. The metal cap 14 is made of a SUS310S stainless alloy. The thermistor element 2 is connected to the metal core wire 7 protruding from the tip of the outer cylinder 21 of the sheath member 8 through its own electrode wire (Pt / Rh alloy wire) 9. The rear end 132 side of the metal cap 14 is open, and laser welding is performed in the circumferential direction with the inner peripheral surface of the rear end 132 overlapping the outer peripheral surface of the outer cylinder 21 of the sheath member 8. Yes. Thereby, the metal cap 14 is fixed to the sheath member 8 in an airtight state.

  As described above, the flange 4 includes the sheath portion 42 that extends in the axial direction, and the protruding portion 41 that is located on the distal end side of the sheath portion 42 and projects outward in the radial direction. The sheath portion 42 has a two-stage shape including a front end side step portion 44 located on the front end side and a rear end step portion 43 having an outer diameter smaller than that of the front end side step portion 44.

  The sheath member 8 is fixed to the flange 4 by being crimped radially inward at a predetermined position on the outer peripheral surface of the sheath portion 42 in a state where the rear end side of the sheath member 8 is inserted into the flange 4. . Further, the overlapping portion of the outer peripheral surface of the outer cylinder 21 of the sheath member 8 and the inner peripheral surface of the rear end side step portion 43 of the sheath portion 42 is laser welded in the circumferential direction. As a result of this laser welding, as shown in FIG. 9, a welded portion L3 straddling the rear end side step portion 43 of the sheath portion 42 and the sheath member 8 (specifically, the outer cylinder 21 of the sheath member 8) is formed. The sheath member 8 is fixed to the flange 4.

  Thus, the welding strength between the flange 4 and the sheath member 8 is increased by performing laser welding on the rear end side step portion 43 of the sheath portion 42 while the sheath member 8 is crimped and fixed to the sheath portion 42 of the flange 4. While being excellent, it can be set as the temperature sensor 100 which is excellent in the adhesive strength of the flange 4 and the sheath member 8. FIG. Therefore, even if the temperature sensor 100 is subjected to strong vibration in an environment where vibration is intense such as an automobile, the sheath member 8 is difficult to shake, and breakage of the sheath member 8 can be suppressed.

  In the temperature sensor 100 configured as described above, the thermistor element 2 is accommodated in a sealed space formed by the sheath member 8 and the metal cap 14. Since the sheath member 8 and the metal cap 14 are exposed to a high temperature environment as high as 1000 ° C., the sheath member 8 and the metal cap 14 have sufficient heat resistance and need to prevent characteristic changes. Therefore, the sheath member 8 and the metal cap 14 are formed of SUS310S. The sheath member 8 and the metal cap 14 are also subjected to heat treatment (oxidation treatment) for forming an oxide film by the first heat treatment step and the second heat treatment step in the same manner as in the first embodiment. A heat treatment (baking treatment) for desorption of hydrogen contained in the heat treatment step is performed. The metal cap 14 on which the oxide film is formed is welded to the sheath member 8, and the other parts 2, 6, 7, 11 to 13 are assembled to each other, thereby completing the manufacture of the temperature sensor 100 shown in FIG.

  In this temperature sensor 100, since the surfaces of the sheath member 8 and the metal cap 14 which are metal surrounding members are covered with an oxide film having a continuous and sufficient film thickness, even if the sheath is exposed to a high temperature of 1000 ° C. or longer for a long time. The progress of oxidation on the surfaces of the member 8 and the metal cap 14 can be suppressed. Moreover, since the hydrogen content of the sheath member 8 and the metal cap 14 is reduced to a specific value or less by the baking process, the amount of hydrogen desorbed from the sheath member 8 and the metal cap 14 can be reduced. Therefore, the temperature characteristic of the thermistor element 2 used in the temperature sensor 100 can be changed and variations can be suppressed, and a change in the characteristic of the thermistor element 2 can be suppressed to prevent a decrease in detection accuracy. A temperature sensor can be provided.

C. Variations:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the scope of the invention.

  For example, in the oxidation treatment in the air atmosphere in the first heat treatment step of the above embodiment, the treatment temperature is 1000 ° C. and the treatment time is 10 hours. In the oxidation treatment in a wet hydrogen atmosphere in the second heat treatment step, wet hydrogen: dry hydrogen = 1: 2.2, treatment temperature is 1150 ° C., and treatment time is 1 hour. However, these conditions are examples, and can be implemented under various conditions described in, for example, Japanese Patent Application Laid-Open No. 2004-301679, which is one of the prior art documents.

  Moreover, in the baking process by the 3rd heat processing process of the said Example, process temperature is 700 degreeC and process time is 30 minutes. However, this condition is only an example, and the treatment temperature is 400 ° C. to 900 ° C., the treatment time is 30 hours to 10 minutes (400 ° C .: 30 hours, 900 ° C .: 10 minutes), and the oxidation does not proceed. It can be carried out under various conditions capable of desorbing hydrogen.

  In the fourth heat treatment step (annealing treatment) of the above embodiment, the treatment temperature is 1100 ° C. and the heat treatment time is 2 hours in a hydrogen atmosphere. However, these conditions are only examples, and can be implemented under various conditions as long as stress can be relaxed during processing.

  Further, in the fifth heat treatment step (baking treatment, hydrogen desorption treatment) in the above embodiment, the treatment conditions are set as No. in FIG. 1-No. Up to 8. However, this condition is merely an example, and the heat treatment step may be performed by appropriately combining the treatment temperature of 200 ° C. to 400 ° C. and the heat treatment time of 10 hours to 40 hours. Further, it can be carried out under various conditions capable of desorbing the contained hydrogen.

  Furthermore, the heat resistant alloy used for each of the metal surrounding members 3, 4, 8 is not limited to SUS310S, and SUS309S, Inconel 601 or the like may be used. Various heat-resistant alloys can be used as long as they are heat-resistant alloys containing 18% by weight or more of chromium. For example, SUS304, SUS304L, or SUS304N1 can be used as the heat-resistant alloy containing at least 18% by weight of chromium element.

  In the above embodiment, the case where the heat treatment (baking) treatment by the third heat treatment step is performed after the heat treatment (oxidation treatment) by the first heat treatment step and the second heat treatment step is shown as an example. However, it is possible to omit either the first heat treatment step or the second heat treatment step.

  The temperature sensor of the present invention can be applied not only to an exhaust temperature sensor but also to a temperature sensor attached to a flow passage through which a liquid such as water or oil flows as a fluid to be measured.

It is a fragmentary sectional view which shows the structure of the temperature sensor as 1st Example of this invention. It is process drawing which shows the process part of the heat processing in the manufacturing process of a temperature sensor. It is a graph which shows the result of having analyzed the relationship between atmospheric temperature and desorption hydrogen about the metal tube which implemented the 1st and 2nd heat processing. Similarly, it is a graph which shows the result of having analyzed the relationship between atmospheric temperature and desorption hydrogen about the sheath member which implemented the 1st and 2nd heat processing. It is a graph which shows the result of having analyzed the relationship between atmospheric temperature and desorption hydrogen about the metal tube which implemented the baking process. It is a graph which shows the result of having analyzed the relationship between atmospheric temperature and desorption hydrogen about the sheath member which implemented the baking process similarly. It is a graph which shows the variation in resistance value of the temperature sensor produced using the metal tube which performed the baking process, a flange, and a sheath member. It is a graph which shows the dispersion | variation in the resistance value of the temperature sensor produced using the metal tube which does not implement a baking process as a comparative example, a flange, and a sheath member. It is a fragmentary sectional view which shows the structure of the temperature sensor as 2nd Example of this invention. It is process drawing which shows the process part of the heat processing of a cylindrical member. It is a graph which shows the relationship between the atmospheric temperature about the some metal tube which implemented the 1st and 2nd heat processing, and the amount of hydrogen generated per unit time. It is a graph which shows the relationship between the atmospheric temperature about the some metal tube which implemented 1st and 2nd heat processing, and the cumulative value of desorption hydrogen. It is a graph which shows the relationship between the atmospheric temperature about the some sheath member which implemented the 1st and 2nd heat processing, and the amount of hydrogen generated per unit time. It is a graph which shows the relationship between the atmospheric temperature about the some sheath member which implemented 1st and 2nd heat processing, and the cumulative value of desorption hydrogen. It is a graph which shows the relationship between the atmospheric temperature about the some metal tube which implemented the baking process, and the amount of hydrogen generated per unit time. It is a graph which shows the relationship between the atmospheric temperature about the some metal tube 3 which implemented the baking process, and the cumulative value of desorption hydrogen. It is a graph which shows the relationship between the atmospheric temperature about the some sheath member which implemented the baking process, and the amount of hydrogen generated per unit time. It is a graph which shows the relationship between the atmospheric temperature about the some sheath member which implemented the baking process, and the cumulative value of desorption hydrogen. It is a graph which shows the relationship between the atmospheric temperature about the some cylindrical member which implemented the 4th heat treatment process, and the amount of hydrogen generated per unit time. It is a graph which shows the relationship between the atmospheric temperature about the some cylindrical member which implemented the 4th heat treatment process, and the cumulative value of desorption hydrogen. It is a graph which shows the relationship between the atmospheric temperature about the cylindrical member which implemented the 5th heat processing process, and the hydrogen content which generate | occur | produced per unit time. It is a graph which shows the relationship between the atmospheric temperature of the cylindrical member which implemented the 5th heat processing process, and the cumulative value of desorption hydrogen. It is a graph which shows the result of the repeated temperature measurement implemented using the temperature sensor produced using the cylindrical member which does not implement a 5th heat processing process. It is a graph which shows the result of the repeated temperature measurement implemented using the temperature sensor produced using the cylindrical member which implemented the 5th heat processing process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Temperature sensor 2 ... Thermistor element 3 ... Metal tube (enclosure member)
4. Flange (mounting member)
6 ... Fitting (tubular member)
8 ... Sheath member 14 ... Metal cap (enclosure member)
100 ... temperature sensor

Claims (11)

The thermistor element is connected to the metal core wire protruding from the tip of the outer cylinder in the sheath member formed by insulatingly holding the metal core wire inside the metal outer cylinder, one end is closed and the other end is opened In the temperature sensor in which the space from the thermistor element to the region of the sheath member including at least the tip of the outer cylinder is accommodated in the internal space of the metal surrounding member,
An oxide film is formed on the surfaces of the surrounding member and the sheath member, the hydrogen content of the sheath member is 8 ppm or less, and the hydrogen content of the surrounding member is higher than the hydrogen content of the sheath member. A temperature sensor characterized by being small. The temperature sensor according to claim 1, wherein
The temperature sensor characterized by the hydrogen content of the surrounding member being 6 ppm or less. The temperature sensor according to claim 1, wherein
The temperature sensor characterized by the hydrogen content of the surrounding member being 5 ppm or less. The temperature sensor according to any one of claims 1 to 3,
A surrounding member that surrounds the outer peripheral surface of the surrounding member, and a mounting member for mounting the temperature sensor on a mounting target body;
A tubular member that surrounds the rear end side of the sheath member protruding from the other end of the surrounding member, and is fixed to the attachment member;
The temperature sensor characterized by the hydrogen content of the said cylindrical member being 4 ppm or less. The thermistor element is connected to the metal core wire protruding from the tip of the outer cylinder in the sheath member formed by insulatingly holding the metal core wire inside the metal outer cylinder, one end is closed and the other end is opened In the manufacturing method of the temperature sensor in which the space from the thermistor element to the region of the sheath member including at least the distal end portion of the outer cylinder is accommodated in the internal space of the metal surrounding member that is,
A wet hydrogen atmosphere oxidation treatment step of performing heat treatment on the surrounding member and the sheath member in a wet hydrogen atmosphere to oxidize the metal surfaces of the surrounding member and the sheath member;
The enclosure member and the sheath member that have undergone the oxidation treatment step in the wet hydrogen atmosphere are subjected to heat treatment in an atmosphere that does not contain hydrogen to desorb hydrogen contained in the enclosure member and the sheath member. A hydrogen desorption treatment step,
A method for manufacturing a temperature sensor, comprising: The method of manufacturing a temperature sensor according to claim 5, further comprising:
Prior to the oxidizing treatment step in the wet hydrogen atmosphere, the surrounding member and the sheath member are heat-treated in an air atmosphere to oxidize the metal surfaces of the surrounding member and the sheath member. A method of manufacturing a temperature sensor, comprising a step. In the manufacturing method of the temperature sensor of Claim 5 or Claim 6,
In the hydrogen desorption treatment step, the hydrogen content of the sheath member is desorbed to 8 ppm or less, and the hydrogen content of the surrounding member is desorbed so as to be smaller than the hydrogen content of the sheath member. A method for manufacturing a temperature sensor. In the manufacturing method of the temperature sensor of Claim 7, The said content hydrogen desorption process process desorbs | hangs the hydrogen content of the said surrounding member to 6 ppm or less, The manufacturing method of the temperature sensor characterized by the above-mentioned. In the manufacturing method of the temperature sensor of Claim 7,
In the said hydrogen desorption process, the hydrogen content of the said surrounding member is desorbed to 5 ppm or less, The manufacturing method of the temperature sensor characterized by the above-mentioned. In the manufacturing method of the temperature sensor in any one of Claims 5 thru | or 9,
A surrounding member that surrounds the outer peripheral surface of the surrounding member, and a mounting member for mounting the temperature sensor on a mounting target body;
A tubular member that surrounds the rear end side of the sheath member protruding from the other end of the surrounding member, and is fixed to the attachment member;
A hydrogen desorption step of desorbing hydrogen contained in the cylindrical member by performing a heat treatment in an atmosphere not containing hydrogen on the cylindrical member;
A method for manufacturing a temperature sensor, further comprising: In the manufacturing method of the temperature sensor of Claim 10,
In the hydrogen desorption process, hydrogen is desorbed so that the hydrogen content of the cylindrical member is 4 ppm or less.

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