JP2018036188A - Temperature sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a temperature sensor capable of maintaining excellent responsiveness and heat resistance.SOLUTION: A temperature sensor 1 includes: a first element wire 21 and a second element wire 22 which form a thermocouple, and which are made of a dissimilar metal material; a temperature measurement contact 23 at which the first element wire 21 and the second element wire 22 are joined together; an element tube 3 for covering the temperature measurement contact 23; and insulating powder 4 which is arranged in the element tube 3, and which insulates the first element wire 21, the second element wire 22, the temperature measurement contact 23, and the element tube 3. The first element wire 21 is thicker than the second element wire 22.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a temperature sensor including a pair of strands made of different metal materials.

In a temperature sensor that measures the temperature of exhaust gas from an internal combustion engine, in addition to the thermistor type, which utilizes the change in electrical resistance in response to a temperature change, an electromotive force generated in a pair of strands in response to a temperature change A thermocouple type utilizing the fact that the temperature changes is used.
In a thermocouple type temperature sensor, a pair of strands and a temperature measuring contact where the pair of strands are combined are covered with a metal tube, and the pair of strands and the temperature measuring contact are covered with insulating powder. Fixed in the tube. For example, in the metal sheath cable of Patent Document 1, it is described that a pair of thermocouple conductors is fixed in a sheath alloy by a mineral insulating material. Further, for example, in the sample temperature detection device of Patent Document 2, of two types of thermocouple wires having different thicknesses, the thicker strand is inserted into the reinforcement pipe, and the thinner strand is inserted into the reinforcement pipe. It is described that it is arranged outside of.

JP-A-63-293133 Japanese Patent Laid-Open No. 4-62460

  In a temperature sensor using a metal sheath, cable, etc. of Patent Document 1, in order to increase the responsiveness of measuring temperature, a pair of strands are narrowed and a bare tube is narrowed to reduce the heat capacity of the temperature sensor. Can be considered. However, in a temperature sensor that measures the temperature in a high-temperature environment such as exhaust gas, a pair of strands are fixed inside the strand by insulating powder, and each of the pair of strands, the insulating powder, and the strand Thermal stress occurs due to the difference in expansion coefficient.

In particular, when the pair of strands becomes thin, the strength of the pair of strands decreases, and the pair of strands may be broken by thermal stress. Therefore, in order to maintain the responsiveness and heat resistance of the temperature sensor, further ingenuity is required.
In addition, the thermocouple strand in patent document 2 is not being fixed with the insulating powder inside the strand. Therefore, Patent Document 2 does not disclose any device for maintaining the heat resistance of the thermocouple element.

  The present invention has been made in view of such problems, and has been obtained in an attempt to provide a temperature sensor that can maintain good responsiveness and heat resistance.

In one aspect of the present invention, the first strand (21) and the second strand (22) made of different metal materials for forming a thermocouple are combined with the first strand and the second strand. A temperature measuring contact (23), an element tube (3) covering the temperature measuring contact, and the first element wire, the second element wire, the temperature measuring contact, and the element tube disposed in the element tube; And insulating powder (4) for insulating and fixing,
The second strand is in a temperature sensor that is narrower than the first strand.

  In the temperature sensor, the first element wire, the second element wire, and the temperature measuring contact disposed in the element tube are insulated from the element tube by the insulating powder and fixed to the element tube. The second strand is thinner than the first strand. As the second element wire becomes thinner, the element tube can also become thinner. Thereby, the heat capacity of the temperature sensor is reduced, and the responsiveness when the temperature is measured by the temperature sensor can be favorably maintained. Further, among the pair of strands, a strand having a material that is weak against thermal stress is a first strand, and a strand having a material that is resistant to thermal stress is a second strand. The heat resistance (heat stress resistance) can be maintained well.

  Therefore, according to the temperature sensor, it is possible to maintain good responsiveness and heat resistance.

  Further, when the temperature sensor is assembled, the first strand and the second strand can be identified by checking the difference in thickness between the first strand and the second strand. As a result, the polarities of the first and second strands can be identified without using special marks or marks. Therefore, the assembling property of the temperature sensor using the thermocouple can be improved.

  Note that the reference numerals in parentheses of the constituent elements shown in one embodiment of the present invention indicate the correspondence with the reference numerals in the drawings in the embodiment, but the constituent elements are not limited only to the contents of the embodiments.

FIG. 3 is an explanatory diagram illustrating a main part of a temperature sensor according to the first embodiment. The II-II sectional view taken on the line of FIG. 1 which shows the principal part of the temperature sensor concerning Embodiment 1. FIG. BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which shows the whole temperature sensor concerning Embodiment 1. FIG. Explanatory drawing which shows the principal part of the other temperature sensor concerning Embodiment 1. FIG. Explanatory drawing which shows the state which removed the outer tube | pipe and insulator in the front-end | tip part of MI cable concerning Embodiment 1. FIG. Explanatory drawing which shows the state which joined the front-end | tip of a pair of strand in the MI cable concerning Embodiment 1. FIG. BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which shows the state which arrange | positions a temperature measuring contact and a pair of element wire in the insulating powder paste arrange | positioned at the elementary tube concerning Embodiment 1. Explanatory drawing which shows the principal part of the temperature sensor concerning Embodiment 2. FIG. The IX-IX sectional view taken on the line of FIG. 8 which shows the principal part of the temperature sensor concerning Embodiment 2. FIG. FIG. 9 is a cross-sectional view corresponding to the line IX-IX in FIG. 8, showing a main part of another temperature sensor according to Embodiment 2. Explanatory drawing which shows the state which has arrange | positioned an insulator tube to a pair of strand in the MI cable concerning Embodiment 2, and joined the front-end | tip of a pair of strand. Explanatory drawing which shows the state which arrange | positions a temperature measuring contact, a pair of strand, and an insulator tube in the insulating powder paste arrange | positioned at the elementary tube concerning Embodiment 2. FIG.

A preferred embodiment of the above-described temperature sensor will be described with reference to the drawings.
(Embodiment 1)
As shown in FIGS. 1 and 2, the temperature sensor 1 of the present embodiment includes a first strand 21 and a second strand 22 made of different metal materials for forming a thermocouple, and a first strand 21 and a second strand. A temperature measuring contact 23 in which two element wires 22 are combined, an element tube 3 that covers the temperature measuring contact 23, and a first element wire 21, a second element wire 22, and a temperature measuring contact 23 Insulating powder 4 that insulates the tube 3 is provided. The first strand 21 is thicker than the second strand 22.

Hereinafter, the temperature sensor 1 of this embodiment will be described in detail.
As shown in FIG. 1, the raw tube 3 is made of metal and has a bottomed cylindrical shape, and is attached to the tip of a metal outer tube 5. The first strand 21 and the second strand 22 are inserted into the outer tube 5 in a state of being parallel to each other, and in the outer tube 5, insulation for fixing the strands 21 and 22 in an insulated state. The object 51 is filled. The insulator 51 may be a ceramic insulating powder or a ceramic solid insulating tube. The insulator 51 may be a combination of ceramic insulating powder and a solid insulating tube. The ceramic constituting the insulator 51 is made of MgO (magnesia).
In the temperature sensor 1 of this embodiment, the side inserted into the exhaust pipe 7 is referred to as the front end side, and the opposite side is referred to as the rear end side.

  As shown in FIG. 3, the temperature sensor 1 of the present embodiment is disposed in the exhaust pipe 7 of the vehicle and measures the temperature of the exhaust gas G flowing through the exhaust pipe 7. At the rear end portion of the outer tube 5, a latching member 52 that is latched in an insertion hole 71 provided in the exhaust pipe 7 is provided. The temperature sensor 1 is attached to the exhaust pipe 7 by tightening the nipple 53 disposed on the outer periphery of the outer pipe 5 in the insertion hole 71 in a state where the hooking member 52 is hooked on the insertion hole 71.

  The retaining member 52 is provided with a mounting outer tube 54 extending from the retaining member 52 to the rear end side. In the attachment outer tube 54, lead wires 55 to which a pair of strands 21 and 22 drawn from the insulator 51 to the rear end side are respectively connected are arranged. Each lead wire 55 is connected to a control device. Each lead wire 55 is held in the mounting outer tube 54 by a rubber bush 56.

  As shown in FIG. 1, the first strand 21 and the second strand 22 are made of different types of metals. One end of the first strand 21 and the second strand 22 is connected as a temperature measuring contact (temperature contact) 23 in the element tube 3. The other ends of the first strand 21 and the second strand 22 are connected as cold junctions via the lead wires 55 and the like. And the temperature sensor 1 measures temperature using the Seebeck effect which an electromotive force produces by the temperature difference between the temperature measuring contact 23 and the cold junction.

The insulating powder 4 in the raw tube 3 is composed of ceramic particles. The linear expansion coefficient of the first strand 21 and the linear expansion coefficient of the second strand 22 are larger than the linear expansion coefficient of the insulating powder 4. Further, the linear expansion coefficient of the second strand 22 that is thinner than the first strand 21 is smaller than the linear expansion coefficient of the first strand 21. In other words, one of the pair of strands 21 and 22 that has the larger linear expansion coefficient is the first strand 21 and the pair of strands 21 and 22 that has the smaller linear expansion coefficient. The line is a second strand 22. The ceramic constituting the insulating powder 4 is made of Al ₂ O ₃ (alumina).

  The difference between the linear expansion coefficient of the second strand 22 and the linear expansion coefficient of the insulating powder 4 is smaller than the difference between the linear expansion coefficient of the first strand 21 and the linear expansion coefficient of the insulating powder 4. When the temperature sensor 1 is exposed to the exhaust gas G and has a high temperature, the thermal stress generated between the second strand 22 and the insulating powder 4 that is thinner than the first strand 21 is the first strand 21 and the insulating powder. 4 and smaller than the thermal stress generated between the two.

  As shown in FIG. 1, in the temperature sensor 1 of the present embodiment, the temperature measuring contact 23 and the whole of the first strand 21 and the second strand 22 are embedded in the insulating powder 4. The insulating powder 4 includes aggregate particles such as ceramic powder, a glass component, and the like. The temperature measuring contact 23 is formed in a substantially spherical shape by melting and integrating the tip of the first strand 21 and the tip of the second strand 22. The first strand 21 can have a wire diameter (outer diameter) of 0.3 to 1.2 mm, and the second strand 22 can have a wire diameter (outer diameter) of 0.1 to 1.0 mm.

  The distance between the first strand 21 and the second strand 22 is constant in the outer tube 5 and is closest to the temperature measuring contact 23. The raw tube 3 is formed with a diameter reduced stepwise from the proximal end side which is the outer tube 5 side toward the distal end side which is the temperature measuring contact 23 side. The base tube 3 includes a proximal end side tube portion 31 attached to the outer periphery of the outer tube 5, an intermediate tube portion 32 connected to the distal end side of the proximal end side tube portion 31 and having a diameter smaller than that of the proximal end side tube portion 31. And a distal end side tube portion 33 which is connected to the distal end side of the intermediate tube portion 32 and has a diameter smaller than that of the intermediate tube portion 32. The distal end of the distal end side tube portion 33 is closed by a hemispherical distal end bottom portion 331. The proximal end side pipe portion 31 is fixed to the outer periphery of the outer tube 5 by caulking 311 and joining.

  As shown in FIG. 4, a cavity K not filled with the insulating powder 4 may be formed in a portion of the raw tube 3 adjacent to the tip of the outer tube 5. Also in this case, the temperature measuring contact 23 and the tip side portions of the strands 21 and 22 connected to the temperature measuring contact 23 are embedded in the insulating powder 4. In the case where the cavity K is formed, it is difficult for heat shrinkage from the distal end portion of the temperature sensor 1 provided with the temperature measuring contact 23 to the proximal end side of the temperature sensor 1, and the responsiveness of the temperature sensor 1 is improved. The decrease can be suppressed.

  The first strand 21 and the second strand 22 of this embodiment are round wires and have a circular cross section. The first strand 21 and the second strand 22 do not necessarily have a circular cross section, and may have a cross section such as an elliptical shape or a flat shape. In any case, when comparing the thicknesses of the first strand 21 and the second strand 22, the strand having the larger cross-sectional area is set as the first strand 21, and the cross-sectional area is smaller. The strand can be the second strand 22.

The temperature sensor 1 of this embodiment can be manufactured as follows.
The temperature sensor 1 is manufactured using an MI cable (inorganic insulating cable) in which a pair of strands 21 and 22 are inserted through an insulator 51 in an outer tube (sheath) 5. The wire diameters of the pair of strands 21 and 22 in the MI cable are made different from each other so that the strand having the larger linear expansion coefficient becomes thicker.

  First, as shown in FIG. 5, the outer tube 5 and the insulator 51 at the tip of the MI cable are removed, and the pair of strands 21 and 22 are exposed. Next, as shown in FIG. 6, the tips of the pair of strands 21 and 22 exposed at the tip of the MI cable are brought close to each other, the tips of the pair of strands 21 and 22 are joined by laser welding, and the temperature measuring contact 23 Form.

Next, as shown in FIG. 7, an insulating powder paste 40 containing ceramic powder, a glass component, and a solvent is disposed inside the bottomed cylindrical element tube 3. Then, the outer tube 5 of the MI cable is inserted into the element tube 3, and the temperature measuring contact 23 and the pair of element wires 21 and 22 are disposed in the insulating powder paste 40 disposed in the element tube 3, and the temperature sensor 1 intermediate is formed. Next, after heating the intermediate and volatilizing the solvent in the insulating powder paste 40, as shown in FIG. 1, caulking 311 and welding are performed on the base tube 3, and the base tube 3 is connected to the outer tube 5 of the MI cable. Secure to.
Thus, the insulating powder paste 40 becomes the insulating powder 4, and the temperature sensor 1 in which the temperature measuring contact 23 and the pair of strands 21 and 22 are insulated and fixed in the element tube 3 by the insulating powder 4 is formed.

  In the temperature sensor 1 of this embodiment, the second strand 22 having a smaller linear expansion coefficient than the first strand 21 is made thinner than the first strand 21. As the second wire 22 is made thinner than the first wire 21, the tube 3 can also be made thin, and the amount of the insulating powder 4 in the tube 3 can be reduced. Thereby, the heat capacity of the temperature measuring tip of the temperature sensor 1 is reduced, and the responsiveness when measuring the temperature by the temperature sensor 1 can be maintained well.

  Further, when the tip of the temperature sensor 1 is heated and cooled in response to the temperature change of the exhaust gas G, the linear expansion coefficient of each of the strands 21 and 22 is larger than the linear expansion coefficient of the insulating powder 4. Tensile stress as thermal stress acts on the wires 21 and 22 in the direction in which the strands 21 and 22 extend, and the wires may be broken in some cases. Therefore, in the temperature sensor 1 of the present embodiment, of the pair of strands 21 and 22, the strand whose linear expansion coefficient is further away from the linear expansion coefficient of the insulating powder 4 is thickened as the first strand 21. Of the pair of strands 21 and 22, the strand having a linear expansion coefficient closer to the linear expansion coefficient of the insulating powder 4 is thinned as the second strand 22.

  By making the linear expansion coefficient of the second strand 22 thin and easy to break compared to the first strand 21 close to the linear expansion coefficient of the insulating powder 4, the tensile stress acting on the second strand 22 from the insulating powder 4 is increased. The tensile stress acting on the first strand 21 from the insulating powder 4 can be made smaller. Thereby, the 2nd strand 22 with a small wire diameter can be effectively protected from the thermal stress which arises when the temperature sensor 1 is used. Therefore, the heat resistance of the temperature sensor 1 can be maintained well.

  Therefore, according to the temperature sensor 1 of the present embodiment, the responsiveness and heat resistance can be maintained well.

  When the temperature sensor 1 is assembled, the first strand 21 and the second strand 22 are identified by checking the difference in thickness between the first strand 21 and the second strand 22. be able to. Thereby, the polarities of the first strand 21 and the second strand 22 can be identified without using a special mark or mark. Therefore, the assembly property of the temperature sensor 1 using a thermocouple can be improved.

(Embodiment 2)
As shown in FIGS. 8 and 9, the temperature sensor 1 of the present embodiment is configured by inserting a pair of strands 21 and 22 in the elementary tube 3 into the insulator tube 6.
The insulator tube 6 is formed with a first insertion hole 61 through which the first strand 21 is inserted and a second insertion hole 62 through which the second strand 22 is inserted. The insulator tube 6 is formed of a ceramic tube member having an outer diameter smaller than that of the outer tube 5. The insulator tube 6 is disposed in the intermediate tube portion 32 and the distal end side tube portion 33 of the base tube 3. The first insertion hole 61 and the second insertion hole 62 in the insulator tube 6 are configured so that the first strand 21 and the second strand 22 arranged in parallel with each other in the outer tube 5 are maintained in a mutually parallel state. It is formed at the position to be inserted.

As shown in FIG. 9, the second insertion hole 62 in the insulator tube 6 of this embodiment is formed in accordance with the size of the first insertion hole 61. The inner diameter of the first insertion hole 61 and the inner diameter of the second insertion hole 62 are the same. Compared to the gap S1 between the first insertion hole 61 and the first strand 21, the second insertion hole 62 and the second insertion hole 62 are the same. The gap S2 with the strand 22 is large. The insulating powder 4 disposed in the raw tube 3 is also filled in the gap S1 between the first insertion hole 61 and the first strand 21 and the gap S2 between the second insertion hole 62 and the second strand 22. . The insulating powder 4 is also filled in the gap S3 between the base tube 3 and the insulator tube 6.
As shown in FIG. 10, the second insertion hole 62 is formed smaller than the first insertion hole 61, and the size of the gap S <b> 1 between the first insertion hole 61 and the first strand 21 is the second insertion hole 61. The size of the gap S2 between the hole 62 and the second strand 22 may be the same.

The temperature sensor 1 of this embodiment can be basically manufactured in the same manner as the temperature sensor 1 shown in the first embodiment.
In the manufacturing method of this embodiment, as shown in FIG. 11, the insulator tube 6 is disposed on the pair of strands 21 and 22 exposed at the tip of the MI cable. At this time, the first strand 21 is inserted into the first insertion hole 61 of the insulator tube 6, and the second strand 22 is inserted into the second insertion hole 62 of the insulator tube 6. And the temperature measuring contact 23 is formed in the front-end | tip of a pair of strands 21 and 22. FIG. As shown in FIG. 12, when inserting the outer tube 5 of the MI cable into the elementary tube 3, the temperature measuring contact 23, the pair of strands 21, 22 and the insulator tube 6 are arranged. Thereafter, in the same manner as the manufacturing method shown in the first embodiment, the temperature sensor 1 in which the temperature measuring contact 23 and the pair of strands 21 and 22 are insulated and fixed in the elementary tube 3 by the insulating powder 4 and the insulator tube 6 is obtained. Form.

In this embodiment, by using the insulator tube 6, it is possible to more reliably insulate between the pair of strands 21 and 22 and the elementary tube 3. In addition, since the gaps S1 and S2 are also filled with the insulating powder 4, the strands 21 and 22 and the insulator tube 6 can be fixed.
Also in the temperature sensor 1 of the present embodiment, the other configurations are the same as in the case of the first embodiment. In addition, components and the like indicated by the same reference numerals as those in the first embodiment are the same as those in the first embodiment. Also in this embodiment, the same effect as that of the first embodiment can be obtained.

(Embodiment 3)
In the present embodiment, the first strand 21 and the second strand 22 in the temperature sensor 1 are shown as different from the first and second embodiments.
As one aspect, the tensile strength of the second strand 22 that is thinner than the first strand 21 can be greater than the tensile strength of the first strand 21. In this case, the strand having the smaller tensile strength of the pair of strands 21 and 22 is defined as the first strand 21 and the strand having the greater tensile strength of the pair of strands 21 and 22 is defined. The second strand 22 is assumed.

  By making the tensile strength of the second strand 22 thinner and easier to break than the first strand 21 to be larger than the tensile strength of the first strand 21, the first strand 21 and the second strand from the insulating powder 4. When the wire 22 receives thermal stress, the second strand 22 can be made difficult to break. Thereby, the 2nd strand 22 in which the wire diameter became small can be effectively protected from the thermal stress produced at the time of use of the temperature sensor 1.

As another aspect, the first strand 21 and the second strand 22 can be determined by the strength-stress ratio defined below.
Specifically, for the first strand 21, the longitudinal elastic modulus is E1, the linear expansion coefficient is α1, the tensile strength is σ1, and for the second strand 22, the longitudinal elastic modulus is E2, the linear expansion coefficient is α2, When the tensile strength is σ2, the strength-stress ratio E2 / α2 / σ2 of the second strand 22 that is thinner than the first strand 21 is smaller than the strength-stress ratio E1 / α1 / σ1 of the first strand 21. To do.

  The thermal stress K1 generated in the first strand 21 is expressed by K1 = E1 · α1 · ΔT, where ΔT is a temperature change amount defined as a constant value. Further, the thermal stress K2 generated in the second strand 22 is expressed by K2 = E2 · α2 · ΔT. The temperature change amount ΔT can be a value obtained by subtracting the temperature before rising from the temperature after rising in the temperature change of the exhaust gas G whose temperature is measured by the temperature sensor 1. The temperature change amount ΔT when calculating the thermal stress K1 generated in the first strand 21 and the temperature change amount ΔT when calculating the thermal stress coefficient K2 generated in the second strand 22 are the same. Therefore, instead of comparing K1 / σ1 and K2 / σ2, E1 · α1 / σ1 and E2 / α2 / σ2 are compared so that E1 · α1 / σ1> E2 · α2 / σ2 is satisfied. be able to.

  The strength-stress ratio is a value indicating the magnitude of thermal stress that can occur in each of the strands 21 and 22 with respect to the magnitude of the tensile strength inherent in each of the strands 21 and 22. It shows that the larger the value of the strength-stress ratio, the weaker the wire becomes and the easier it is to break. By reducing the strength stress ratio E2 / α2 / σ2 of the second strand 22 that is thinner than the first strand 21, compared to the strength-stress ratio E1 / α1 / σ1 of the first strand 21, the insulating powder 4 When the first strand 21 and the second strand 22 are subjected to thermal stress, the second strand 22 can be made difficult to break. Thereby, the 2nd strand 22 in which the wire diameter became small can be effectively protected from the thermal stress produced at the time of use of the temperature sensor 1.

In this example, an example is shown in which a plurality of types of thermocouples having different materials used for the first strand 21 and the second strand 22 are formed.
Table 1 shows a combination of metals used for the first strand 21 and the second strand 22 according to a first embodiment using a K type thermocouple, a second embodiment using an N type thermocouple, and a second embodiment using an R type thermocouple. 3, the value of the linear expansion coefficient α (/ ° C.) of the first strand 21 and the second strand 22 is shown. Here, the insulating powder 4 is made of alumina, and the linear expansion coefficient of alumina is 8.6 × 10 ⁻⁶ (/ ° C.).

Example 1
In the K type thermocouple, the first strand 21 thicker than the second strand 22 can be formed by chromel, and the second strand 22 can be formed by alumel. In this case, the linear expansion coefficient α2 of the second strand 22 is slightly smaller than the linear expansion coefficient α1 of the first strand 21.

(Example 2)
In the N type thermocouple, the first strand 21 thicker than the second strand 22 is formed of a Ni—Cr—Si alloy (nickel-chromium-silicon alloy), and the second strand 22 is formed of a Ni—Si alloy. (Nickel-silicon alloy). In this case, the linear expansion coefficient α2 of the second strand 22 is slightly smaller than the linear expansion coefficient α1 of the first strand 21.

(Example 3)
The R type thermocouple is configured using Pt (platinum) and a Pt—Rh alloy (platinum-rhodium alloy). The linear expansion coefficients of Pt and Pt—Rh alloy are the same, and any of the first strand 21 and the second strand 22 may be formed of Pt. In this example, the case where the first strand 21 is formed of Pt and the second strand 22 is formed of a Pt—Rh alloy is shown.

In addition, the 1st strand 21 and the 2nd strand 22 can also be formed with materials other than each material shown to this example.
The present invention is not limited to each embodiment, and can be applied to further different embodiments without departing from the scope of the invention.

DESCRIPTION OF SYMBOLS 1 Temperature sensor 21 1st strand 22 2nd strand 23 Temperature measuring contact 3 Base tube 4 Insulating powder 6 Insulator tube

Claims (4)

A first strand (21) and a second strand (22) made of different metal materials for forming a thermocouple; and a temperature measuring contact (23) in which the first strand and the second strand are combined. An element tube (3) covering the temperature measuring contact, and an insulation which is disposed in the element tube and insulates and fixes the first element wire, the second element wire and the temperature measuring contact and the element tube. Powder (4),
The second strand is a temperature sensor that is thinner than the first strand. The linear expansion coefficient of the first strand and the linear expansion coefficient of the second strand are larger than the linear expansion coefficient of the insulating powder,
The temperature sensor according to claim 1, wherein a linear expansion coefficient of the second strand is smaller than a linear expansion coefficient of the first strand.   The temperature sensor according to claim 1, wherein a tensile strength of the second strand is larger than a tensile strength of the first strand. An insulator pipe (6) in which a first insertion hole (61) for inserting the first element wire and a second insertion hole (62) for inserting the second element wire are disposed in the element pipe. Has been
The insulating powder is also filled in a gap (S1) between the first insertion hole and the first strand and a gap (S2) between the second insertion hole and the second strand. The temperature sensor of any one of -3.

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