WO2019151167A1

WO2019151167A1 - Temperature sensor

Info

Publication number: WO2019151167A1
Application number: PCT/JP2019/002627
Authority: WO
Inventors: 元樹佐藤; 真典辻村
Original assignee: 株式会社デンソー
Priority date: 2018-01-31
Filing date: 2019-01-28
Publication date: 2019-08-08
Also published as: JP2019132726A

Abstract

This temperature sensor (1) is provided with: a pair of thermocouple wires (2); a temperature measurement contact point (3) at which the tips of the pair of thermocouple wires are joined; an outer tube (4) that accommodates the temperature measurement contact point (3) inside a tip part (401); an insulating material (5) that insulates the pair of thermocouple wires (2) and the outer tube (4); and a glass sealing material (6) that is filled in a base end part (402) of the outer tube (4). The temperature measurement contact point (3) is disposed in a gas phase (K) inside the tip part (401) of the outer tube (4). In an axial direction (X) along the center axis line of the outer tube (4), the shortest distance (L) from a base end (301) of the temperature measurement contact point (3) to a tip surface (501) of the insulating material (5) is in the range of 0-0.7 mm.

Description

Temperature sensor

Cross-reference of related applications

This application is based on Japanese Patent Application No. 2018-015628, filed on January 31, 2018, the contents of which are incorporated herein by reference.

The present disclosure relates to a temperature sensor that measures the temperature of a measurement target gas in a measurement environment.

A thermocouple type temperature sensor having a pair of thermocouple wires is used, for example, to measure the temperature of exhaust gas flowing in the exhaust pipe of a vehicle. The pair of thermocouple wires are fixed in the outer tube in an insulated state by an insulating material such as magnesium oxide or aluminum oxide. The thermocouple type temperature sensor includes a grounding type in which the temperature measuring contact is grounded to the tip of the outer tube, and a non-grounded type in which the temperature measuring contact is not grounded to the tip of the outer tube. When responsiveness is mainly required, a grounded type is used, and when noise resistance is mainly required, a non-grounded type is used.

For example, in the sheath thermocouple of Patent Document 1, the tips of the pair of thermocouple wires and the temperature measuring contact are coated with a conductive material having high hardness. And the front-end | tip part and temperature measuring contact of a pair of thermocouple strand covered with coating are embed | buried in the powder of the insulating material in the front-end | tip part of an outer tube | pipe.

JP 2016-2111855 A

In the conventional temperature sensor including the sheathed thermocouple of Patent Document 1, the position where the temperature measuring contact is arranged is not devised when forming a non-grounded thermocouple type temperature sensor. In a non-grounded thermocouple type temperature sensor, since the temperature measuring contact is not in contact with the outer tube, it takes time until the temperature of the temperature measuring contact reaches the temperature of the measurement target gas. The reason for this is that the heat transfer path from the gas to be measured to the temperature measuring contact is formed at a position closer to the tip of the outer tube and is measured via a gas phase such as air at the tip of the outer tube. This is because heat is transferred to the hot junction.

On the other hand, the inventors' diligent research has revealed that the responsiveness of the temperature sensor can be remarkably improved by bringing the proximal end of the temperature measuring contact as close as possible to the distal end surface of the insulating material. The reason for this is that the heat transfer path from the gas to be measured to the temperature measuring contact is formed at the position on the proximal end side of the temperature measuring contact, and does not pass through the gas phase as much as possible, but through a pair of thermocouple wires. It was found that this was because heat was transferred to the temperature measuring junction.

Therefore, in order to improve the responsiveness of a non-grounded thermocouple temperature sensor, it is important to properly set the shortest distance between the base end of the temperature measuring contact and the front end surface of the insulating material. I understood.

This disclosure has been obtained in an attempt to provide a temperature sensor that can improve the responsiveness of a thermocouple type temperature sensor that is an ungrounded type.

One aspect of the present disclosure includes a pair of thermocouple wires made of different metal materials;
A temperature measuring junction in which the tips of the pair of thermocouple wires are combined;
An outer tube made of a metal material and containing the temperature measuring contact in the tip or in the tip cover attached to the tip,
An insulating material that is made of an insulating material, is disposed in the outer tube, insulates the pair of thermocouple wires from the outer tube, and fixes the pair of thermocouple wires to the outer tube; With
The temperature measuring contact is disposed in the gas phase in the tip of the outer tube or in the tip cover,
In the axial direction along the central axis of the outer tube, the shortest distance from the base end of the temperature measuring contact point to the front end surface of the insulating material is in the temperature sensor in the range of 0 to 0.7 mm.

The thermocouple type temperature sensor of the one aspect is a non-grounding type in which the temperature measuring contact is disposed outside the insulating material and in the gas phase in the distal end portion of the outer tube or the distal end cover. In the non-grounded thermocouple type temperature sensor, the shortest distance in the axial direction from the proximal end of the temperature measuring contact to the distal end surface of the insulating material is set within a range of 0 to 0.7 mm. As a result, the temperature measuring contact can be arranged outside the insulating material and at a position as close as possible to the insulating material.

Therefore, a heat transfer path from the measurement target gas to the temperature measuring contact can be formed at the position on the base end side of the temperature measuring contact. Then, heat can be transferred from the measurement target gas to the temperature measuring contact through the outer tube and the pair of thermocouple wires, and can be performed with little through the gas phase. As a result, the responsiveness of the non-grounded thermocouple type temperature sensor can be improved.

When the shortest distance exceeds 0.7 mm, the temperature measuring contact is separated from the insulating material, and it becomes difficult to improve the responsiveness of the temperature sensor.

Therefore, according to the temperature sensor of the one aspect, it is possible to improve the responsiveness of the thermocouple type temperature sensor which is a non-grounded type.

In addition, although the code | symbol of the parenthesis of each component shown in 1 aspect of this indication shows the correspondence with the code | symbol in the figure in embodiment, each component is not limited only to the content of embodiment.

The objectives, features, advantages, and the like of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings. The drawings of the present disclosure are shown below.
FIG. 1 is a cross-sectional view illustrating a main part of a temperature sensor according to an embodiment. FIG. 2 is a cross-sectional view illustrating a temperature sensor according to the embodiment. FIG. 3 is a cross-sectional view showing the periphery of the temperature measuring contact according to the embodiment. 4 is a cross-sectional view taken along the line IV-IV in FIG. 1 according to the embodiment. FIG. 5 is a cross-sectional view illustrating a main part of another temperature sensor according to the embodiment. FIG. 6 is a cross-sectional view showing the periphery of the base end portion of another outer tube according to the embodiment. FIG. 7 is a cross-sectional view showing the periphery of the base end portion of another outer tube according to the embodiment. FIG. 8 is a cross-sectional view showing the periphery of another temperature measuring contact according to the embodiment. FIG. 9 is a cross-sectional view showing a process of forming a temperature measuring contact according to the embodiment. FIG. 10 is a cross-sectional view showing a process of forming another temperature measuring contact according to the embodiment. FIG. 11 is a perspective view showing a tablet for glass sealing material according to the embodiment. FIG. 12 is a flowchart illustrating a manufacturing method of the sheath thermocouple constituting the temperature sensor according to the embodiment. FIG. 13 is an explanatory diagram showing a prepared sheath pin in the manufacturing process of the sheath thermocouple according to the embodiment. FIG. 14 is an explanatory diagram illustrating a state in which the insulating material at the base end portion of the sheath pin is scraped out in the manufacturing process of the sheath thermocouple according to the embodiment. FIG. 15 is an explanatory diagram showing a state in which a temperature measuring contact is formed at the distal ends of a pair of thermocouple wires in the manufacturing process of the sheath thermocouple according to the embodiment. FIG. 16 is an explanatory diagram showing a manufacturing process of the sheath thermocouple according to the embodiment, in which a distal end cover is attached to the distal end portion of the outer tube and a tablet is disposed at the proximal end portion of the outer tube. FIG. 17 is an explanatory diagram illustrating another thermocouple manufacturing process according to the embodiment, in which a pair of thermocouple wires are inserted into the outer tube. FIG. 18 is an explanatory diagram showing a state in which a glass sealing material is filled in the proximal end portion of the outer tube in the manufacturing process of another thermocouple according to the embodiment. FIG. 19 is an explanatory diagram showing a state in which an outer tube is filled with an insulating material in another thermocouple manufacturing process according to the embodiment. FIG. 20 is an explanatory diagram illustrating another thermocouple manufacturing process according to the embodiment in a state in which a temperature measuring contact is formed at the distal ends of a pair of thermocouple wires. FIG. 21 is a cross-sectional view showing the main part of the temperature sensor according to the comparative embodiment. FIG. 22 is a graph showing the relationship between the shortest distance and the 63% response time for the confirmation test.

A preferred embodiment of the above-described temperature sensor will be described with reference to the drawings.
<Embodiment>
As shown in FIGS. 1 and 2, the temperature sensor 1 of this embodiment includes a pair of thermocouple wires 2, a temperature measuring contact 3, an outer tube 4, a tip cover 42, an insulating material 5, and a glass sealing material 6. . Each of the pair of thermocouple wires 2 is composed of different metal materials. The temperature measuring contact 3 is formed by joining the tips of a pair of thermocouple wires 2. The outer tube 4 is made of a metal material, and the temperature measuring contact 3 is accommodated in a tip cover 42 attached to the tip portion 401. The tip cover 42 is attached to the outer periphery of the tip of the outer tube 4 and closes the tip side X1 of the outer tube 4.

The insulating material 5 is made of an insulating material and is disposed in the outer tube 4, and insulates the pair of thermocouple wires 2 from the outer tube 4, thereby connecting the pair of thermocouple wires 2 to the outer tube. 4 is fixed. As shown in FIG. 3, the temperature measuring contact 3 is disposed in the gas phase K in the tip cover 42 at the tip 401 of the outer tube 4. In the axial direction X along the central axis of the outer tube 4, the shortest distance L from the base end 301 of the temperature measuring contact 3 to the front end surface 501 of the insulating material 5 is in the range of 0 to 0.7 mm.

As shown in FIGS. 1 and 2, in the temperature sensor 1 of the present embodiment, the tip end side X <b> 1 is provided with a temperature measuring contact 3 with respect to the outer tube 4 in the axial direction X along the central axis of the outer tube 4. It means the side that was given. The base end side X2 refers to a side opposite to the front end side X1 in the axial direction X.

Hereinafter, the temperature sensor 1 of this embodiment will be described in detail.
(Temperature sensor 1)
As shown in FIG. 2, the temperature sensor 1 is a vehicle-mounted one, and is used to measure the temperature of fluid flowing in an intake pipe or an exhaust pipe of an internal combustion engine (engine) in an automobile. The temperature sensor 1 of the present embodiment is disposed in the exhaust pipe 15 and is used to measure the temperature of exhaust gas as the measurement target gas G in the measurement environment that flows through the exhaust pipe 15. The temperature of the exhaust gas is used when the control device (electronic control unit) 8 performs combustion control of the internal combustion engine. Moreover, the temperature of exhaust gas can be utilized, for example, in order to detect the temperature of the exhaust purification catalyst arranged in the exhaust pipe. Moreover, the temperature sensor 1 can also be arrange | positioned at the intake pipe of the exhaust gas recirculation path | route which recirculates the exhaust gas in an exhaust pipe to an intake pipe, for example.

As shown in FIG. 13, the pair of thermocouple wires 2, the outer tube 4, and the insulating material 5 of the present embodiment are those integrally formed as a sheath pin 12. The main part of the temperature sensor 1 is formed as a sheath thermocouple 11 by a pair of thermocouple wires 2, a temperature measuring contact 3, an outer tube 4, an insulating material 5 and a glass sealing material 6. FIG. 4 shows a cross section orthogonal to the axial direction X of the sheath thermocouple 11 and the sheath pin 12.

As shown in FIG. 2, the temperature sensor 1 includes a first housing 71 and a second housing 72 that hold the sheath thermocouple 11 on the inner peripheral side, a proximal end cover 73 attached to the second housing 72, and a base And a bush 74 held in the end cover 73. The first housing 71 is attached to the outer periphery of the outer tube 4, and the second housing 72 is attached to the outer periphery of the first housing 71. The second housing 72 is attached to an attachment hole provided in the exhaust pipe 15. The bush 74 holds the terminal fitting 75 connected to the pair of thermocouple wires 2.

(Outer tube 4)
The outer tube 4 is also called a sheath tube or a metal sheath, and is made of a metal material such as stainless steel (SUS, NCA) or Ni-base heat-resistant alloy (NCF). As shown in FIG. 13, the outer tube 4 uses the outer tube of a sheath pin 12 having a cylindrical shape. The distal end portion 401 of the outer tube 4 is closed with a metal material. As shown in FIG. 1, the distal end portion 401 of the outer tube 4 of this embodiment is closed by a distal end cover 42 attached to the outer periphery of the distal end portion 401 of the cylindrical portion 41. As shown in FIG. 5, the distal end portion 401 of the outer tube 4 may be closed by a lid portion 42 </ b> A provided continuously from the distal end portion 401 of the cylindrical portion 41. The lid portion 42 </ b> A can be configured by a metal piece welded to the tip of the cylindrical portion 41 of the outer tube 4.

As shown in FIG. 1, the outer tube 4 of the present embodiment includes a cylindrical portion 41 having a cylindrical shape, and a tip cover 42 attached to the outer periphery of the tip of the cylindrical portion 41. The tip cover 42 is joined to the tip outer periphery of the cylindrical portion 41 by welding. The front cover 42 has a cover base end 421 mounted on the outer periphery of the front end of the cylindrical portion 41 and an inner diameter smaller than the inner diameter of the cover base end 421 located on the front end side X1 from the cover base end 421. And a cover tip portion 422 having the same. A curved bottom is formed at the tip of the cover tip 422. The length of the cover front end portion 422 of the front end cover 42 in the axial direction X can be changed as appropriate.

As shown in FIG. 6, a holder 43 for placing the tablet 60 for the glass sealing material 6 can be attached to the base end portion 402 of the outer tube 4. The holder 43 has a funnel shape and has an upper opening 431 having an inner diameter larger than the outer diameter of the outer tube 4. The holder 43 is used to fill the glass material melted by the tablet 60 into the proximal end portion 402 of the outer tube 4. The holder 43 can be press-fitted into the outer periphery of the base end portion 402 of the outer tube 4, and can be caulked and fixed or welded to the outer periphery of the base end portion 402 of the outer tube 4.

The size of the tablet 60 arranged in the holder 43 can be made larger than the case where it is arranged in the proximal end portion 402 of the outer tube 4. And when the tablet 60 arrange | positioned in the holder 43 fuse | melts as a glass material, this glass material can flow in into the base end part 402 of the outer tube | pipe 4 from the holder 43. FIG. Thereby, a lot of glass material can be melted, and sufficient glass material can be supplied into the base end portion 402 of the outer tube 4. Therefore, the inside of the outer tube 4 can be more effectively sealed by the glass sealing material 6.

As shown in FIG. 7, when the holder 43 is used, the glass sealing material 6 can be filled in the holder 43 to seal the base end portion 402 of the outer tube 4. In this case, the inner diameter of the holder 43 can be set larger than the inner diameter of the outer tube 4. And by filling the glass sealing material 6 in the holder 43, it becomes possible to obtain a higher compression effect and to ensure high airtightness in the outer tube 4. In this case, it is also possible to save the trouble of scraping the insulating material 5 from the base end portion of the sheath pin 12 (base end portion 402 of the sheath tube 4). The glass sealing material 6 is more preferably filled up to the maximum diameter portion of the holder 43. In this case, a higher compression effect can be obtained, and the high airtightness of the outer tube 4 can be more effectively ensured.

The inner diameter of the outer tube 4 in this embodiment is in the range of φ1.5 to 10.0 mm. If the inner diameter of the outer tube 4 is smaller than φ1.5 mm, it may be difficult to obtain a compression effect from the base end portion 402 of the outer tube 4 to the glass sealing material 6. The compression effect means that when the heated outer tube 4 and the glass sealing material 6 are cooled, the stress is zero at the glass transition point, and the linear expansion coefficient of the outer tube 4 is that of the glass sealing material 6. By being larger than the linear expansion coefficient, compressive stress is applied from the outer tube 4 to the glass sealing material 6 in a temperature environment below the glass transition point, and the sealing performance (sealing performance) by the glass sealing material 6 is increased. That means. When the inner diameter of the outer tube 4 is larger than φ10.0 mm, the sheath thermocouple 11 is increased in size, which may adversely affect the responsiveness, mountability, etc. of the temperature sensor 1.

Further, when the inner diameter of the outer tube 4 is smaller than φ1.5 mm, the strength of the outer tube 4 is lowered, for example, the temperature sensor 1 is damaged due to vibration caused by the vehicle on which the temperature sensor 1 is mounted, or the thermocouple There is a possibility that the insulation distance between the strands 2 becomes small, and the thermocouple strands 2 break down. However, if these problems can be improved, it is considered that the inner diameter of the outer tube 4 can be reduced to about 1 mm.

(A pair of thermocouple wires 2)
The pair of thermocouple wires 2 are made of different metal materials in order to generate a so-called Seebeck effect. The pair of thermocouple strands 2 in this embodiment constitutes an N type thermocouple (sheath thermocouple 11). With this configuration, it is easy to increase the temperature measurement range by the temperature sensor 1. The temperature sensor 1 of this embodiment can measure the temperature of the high temperature measurement target gas G of 1000 ° C. or higher. The + leg of the thermocouple wire 2 is made of niclosil, which is an alloy mainly composed of Ni (nickel), Cr (chromium), and Si (silicon). The-leg of the thermocouple wire 2 is made of nycil which is an alloy mainly composed of Ni (nickel) and Si (silicon).

The pair of thermocouple wires 2 may constitute various types of thermocouples other than the N type. For example, the pair of thermocouple wires 2 constitutes a K-type thermocouple whose + leg is made of chromel whose main component is Ni and Cr, and whose − leg is made of alumel whose main component is Ni, Al, or Si. It may be a thing.

The diameter of the pair of thermocouple wires 2 is in the range of φ0.01 to 2.0 mm. The diameters of the pair of thermocouple wires 2 in this embodiment are equal to each other. The diameter of the + leg thermocouple element 2 and the diameter of the − leg thermocouple element 2 may be different from each other. It is difficult to make the diameter of the thermocouple wire 2 less than φ0.01 mm from the viewpoint of manufacturing and strength. Moreover, when the diameter of the thermocouple wire 2 exceeds φ2.0 mm, the sheath thermocouple 11 becomes large, which may adversely affect the responsiveness, mountability, and the like of the temperature sensor 1.

As an example, the diameter of the thermocouple wire 2 of this embodiment is φ0.37 mm. The shortest distance L in the axial direction X from the proximal end 301 of the temperature measuring contact 3 to the distal end surface 501 of the insulating material 5 is 0.7 mm or less, which is not more than twice the average diameter of the pair of thermocouple wires 2. Is set.

As shown in FIG. 2, the pair of thermocouple wires 2 are inserted in the outer tube 4 in a state parallel to each other. The pair of thermocouple wires 2 protrudes from the base end portion 402 of the outer tube 4 and is drawn from the outer tube 4 to the base end side X2. The pair of thermocouple wires 2 is connected to an external control device 8 via a terminal fitting 75 and a lead wire 76 provided in the temperature sensor 1. The control device 8 can be a sensor control device (SCU) connected to an engine control device (ECU). The control device 8 can also be constructed in an engine control device.

(Temperature contact 3)
The temperature measuring contact 3 is also called a heat contact and is formed into a ball shape by fusing the metal material constituting the + leg of the pair of thermocouple wires 2 and the metal material constituting the − leg. . The temperature measuring tip 10 of the temperature sensor 1 is formed by the temperature measuring contact 3 and the tip cover 42 positioned around the temperature measuring contact 3. A pair of thermocouple wires 2 of the temperature sensor 1 is connected to an amplifier in the control device 8 via a terminal fitting 75, a lead wire 76, etc., thereby forming a circuit for measuring temperature. A reference contact located on the opposite side to the temperature measuring contact 3 in the pair of thermocouple wires 2 is formed in the control device 8. A temperature difference between the temperature measuring contact 3 and the reference contact generates an electromotive force in the pair of thermocouple wires 2.

As shown in FIG. 1, the temperature measuring contact 3 of this embodiment is arranged in the gas phase K in the tip cover 42 attached to the tip 401 of the outer tube 4. The distal end portion 201 and the temperature measuring contact 3 of the pair of thermocouple wires 2 are disposed at a position protruding from the distal end opening 411 of the cylindrical portion 41 of the outer tube 4 toward the distal end side X1.

In the temperature sensor 1 of this embodiment, the amount by which the pair of thermocouple wires 2 protrude from the distal end portion 401 of the outer tube 4 is made as small as possible, and the temperature measuring contact 3 is positioned as close as possible to the distal end surface 501 of the insulating material 5. Forming. As shown in FIG. 8, the base end 301 of the temperature measuring contact 3 may be disposed at a position in contact with the front end surface 501 of the insulating material 5. With this configuration, the temperature measuring contact 3 can be supported by the insulating material 5, and the vibration resistance of the temperature measuring contact 3 protruding from the tip surface 501 of the insulating material 5 and the tip portion 201 of the pair of thermocouple wires 2 is improved. Can do.

Here, since the temperature measuring contact 3 is formed by fusing the tip portions 201 of the pair of thermocouple wires 2, the base end 301 of the temperature measuring contact 3 is connected to the tip surface 501 of the insulating material 5. It is hard to say that they are always in contact. The “position where the base end 301 of the temperature measuring contact 3 is in contact with the front end surface 501 of the insulating material 5” is not only the case where the base end 301 of the temperature measuring contact 3 is in contact with the front end surface 501 of the insulating material 5. In addition, the case where the base end 301 of the temperature measuring contact 3 is equal to being in contact with the front end surface 501 of the insulating material 5 is also included. When the shortest distance L is in the range of 0 to 0.2 mm, the base end 301 of the temperature measuring contact 3 is included in a position where it contacts the front end surface 501 of the insulating material 5.

The temperature measuring contact 3 is preferably formed in a shape as close to a spherical shape as possible. However, it is difficult to form the temperature measuring contact 3 in a true spherical shape. Further, the temperature measuring contact 3 is preferably formed as small as possible in order to improve the responsiveness of temperature measurement by the temperature sensor 1. On the other hand, since the temperature measuring contact 3 is formed by fusion of the tip portions 201 of the pair of thermocouple wires 2, it is difficult to form the temperature measuring contact 3 less than twice the diameter of the thermocouple wires 2.

The maximum diameter of the temperature measuring junction 3 of this embodiment is not less than 2 times and not more than 3 times the average diameter of the pair of thermocouple wires 2. With this configuration, the temperature measuring contact 3 can be formed as small as possible to ensure the responsiveness of the temperature sensor 1. The “maximum diameter of the temperature measuring contact 3” refers to the length of the longest straight line passing through the temperature measuring contact 3. The temperature measuring contact 3 may have various shapes such as a flat spherical shape, a crushed spherical shape, a long spherical shape, and an ellipsoid in addition to a substantially spherical shape. The temperature measuring contact 3 of this embodiment has an ellipsoid shape that is slightly longer in the direction orthogonal to the axial direction X. The maximum diameter of the temperature measuring contact 3 is measured as the maximum diameter in the direction orthogonal to the axial direction X.

The diameters of the pair of thermocouple wires 2 in this embodiment are equal to each other. The average diameter of the pair of thermocouple wires 2 is the diameter of one of the thermocouple wires 2. On the other hand, when the diameters of the pair of thermocouple strands 2 are different from each other, the average diameter of the pair of thermocouple strands 2 is the diameter of the + legged thermocouple strand 2 and the −legged thermocouple strand. The average value with the diameter of 2.

When the maximum diameter of the temperature measuring contact 3 exceeds three times the average diameter of the pair of thermocouple wires 2, the temperature measuring contact 3 is large, and the heat capacity may affect the response of the temperature sensor 1 to deteriorate. There is.

When forming the temperature measuring contact 3, the tip portions 201 of the pair of thermocouple wires 2 protruding from the tip surface 501 of the insulating material 5 can be deformed so as to approach each other. For example, as shown in FIG. 9, the tip portions 201 of the pair of thermocouple wires 2 protruding from the tip surface 501 of the insulating material 5 approach each other in the axial direction X from a state parallel to the axial direction X. A bent portion 23 that bends in an orthogonal state can be formed. The bent portions 23 may overlap each other. Then, the temperature measuring contact 3 can be formed by melting the bent portions 23 with a laser or the like.

Further, for example, as shown in FIG. 10, the tip portion 201 of the pair of thermocouple wires 2 protruding from the tip surface 501 of the insulating material 5 includes an inclined portion 24 inclined to approach each other, and an inclined portion 24 of the inclined portion 24. A facing portion 25 that faces each other on the distal end side X1 can be formed. Then, the facing portions 25 can be melted with a laser or the like to form the temperature measuring contact 3.

(Insulating material 5)
The insulating material 5 is composed of a metal oxide powder such as magnesium oxide (MgO) or aluminum oxide (Al ₂ O ₃ ). A gap between the inner periphery of the outer tube 4 and the outer periphery of the pair of thermocouple wires 2 is filled with powder of the insulating material 5. A gap is formed between the powders of the insulating material 5. The powder of the insulating material 5 is compressed when molding to reduce the diameter of the sheath pin 12 is performed. The pair of thermocouple wires 2 is held in the outer tube 4 by the powder of the insulating material 5.

The outer tube 4 and the insulating material 5 are formed using a sheath pin 12. Therefore, the distal end surface 501 of the insulating material 5 is not necessarily in the same position as the distal end surface of the cylindrical portion 41 of the outer tube 4 depending on the situation when the sheath pin 12 is cut. As shown in FIG. 3, it is also assumed that the distal end surface 501 of the insulating material 5 is slightly depressed from the distal end opening 411 of the cylindrical portion 41 toward the proximal end X2.

The distal end surface 501 of the insulating material 5 of this embodiment is in the range of 0 to 0.3 mm from the distal end opening 411 of the cylindrical portion 41 to the proximal end side X2. In FIG. 3, the distance from the front end surface 501 of the insulating material 5 to the front end opening 411 of the cylindrical portion 41 is indicated by a symbol M. With this configuration, the temperature measuring contact 3 is prevented from entering the inner peripheral side of the outer tube 4 as much as possible, and the temperature measuring contact 3 can be easily formed. The center surface of the distal end surface 501 of the insulating material 5 may be located on the most proximal side X2. The shortest distance L from the base end 301 of the temperature measuring contact 3 to the front end surface 501 of the insulating material 5 is along the axial direction X from the base end 301 of the temperature measuring contact 3 to the center position of the front end surface 501 of the insulating material 5. It can be calculated as a distance.

(Glass sealing material 6)
As shown in FIG. 1, a glass sealing material 6 for sealing the inside of the outer tube 4 and blocking it from the outside is filled in the base end portion 402 of the outer tube 4. The temperature measuring contact 3, the pair of thermocouple wires 2, and the insulating material 5 in the outer tube 4 are not in contact with an external measurement target gas G or the like. And so on. The glass sealing material 6 is made of Bi glass containing Bi (bismuth) or Pb glass containing Pb (lead). Bi-based glass is mainly composed of Bi ₂ O ₃ (bismuth oxide) and contains other oxides. Other oxides include B ₂ O ₃ , SrO, ZnO, BaO and the like. Pb-based glass contains PbO (lead oxide) as a main component and contains other oxides and the like. Other oxides include B ₂ O ₃ , SrO, ZnO, SiO _{2 and the} like.

The glass encapsulant 6 is formed by using a glass tablet 60 formed in a solid state, and melting and solidifying the tablet 60. As shown in FIG. 11, the tablet 60 has a size that can be inserted into the inner periphery of the base end portion 402 of the outer tube 4 or the inner periphery of the holder 43. The tablet 60 has two insertion holes 601 through which the pair of thermocouple wires 2 can be inserted.

The glass sealing material 6 is formed by using a glass tablet 60 formed in a solid state and solidifying after the tablet 60 is melted. The tablet 60 has a size that can be inserted into the inner periphery of the proximal end portion 402 of the outer tube 4 and has two insertion holes 601 through which the pair of thermocouple wires 2 can be inserted.

(Production method)
Next, a method for manufacturing the sheath thermocouple 11 as the main part of the temperature sensor 1 of the present embodiment will be described with reference to the flowchart of FIG.
First, a sheath pin 12 is prepared in which a pair of thermocouple wires 2 are held by an insulating material 5 in the outer tube 4 (step S1 in FIG. 12). In the sheath pin 12, as shown in FIG. 13, a pair of thermocouple wires 2 protrude from both ends of the distal end side X1 and the proximal end side X2.

Next, as shown in FIG. 14, in a state where the pair of thermocouple wires 2 and the outer tube 4 are maintained, the insulating material 5 at the base end portion of the sheath pin 12 is scraped out (step S2). At this time, the insulating material 5 can be scraped off by performing shot blasting or the like. Further, a space 403 after the insulating material 5 is scraped out is formed in the base end portion 402 of the outer tube 4. Next, as shown in FIG. 15, the tip portions 201 of the pair of thermocouple wires 2 protruding from the tip portions of the sheath pin 12 are faced to each other and melted using a laser or the like, and the tip portions 201 are joined to each other. The temperature measuring contact 3 is formed (step S3).

Next, as shown in FIG. 16, the tip cover 42 is attached to the tip 401 of the outer tube 4 of the sheath pin 12, and the tip cover 42 is caulked and welded to fix it to the tip 401 of the outer tube 4. (Step S4). Note that steps S3 and S4 may be performed before step S2.

In step S4, when the tip cover 42 is fixed to the tip portion 401 of the outer tube 4, an air layer may be formed between the outer tube 4 and the tip cover 42. This air layer is preferably eliminated when caulking, and the absence of the air layer can realize higher responsiveness of the temperature sensor 1. This is because, when the temperature of the measurement target gas G is transmitted to the outer tube 4, if there is an air layer with low thermal conductivity, the heat transfer is blocked by the air layer.

Next, as shown in the figure, the tablet 60 for forming the glass sealing material 6 is disposed in the space 403 of the base end portion 402 of the outer tube 4 (step S5). At this time, the base end portions 202 of the pair of thermocouple wires 2 protruding from the base end portion 402 of the outer tube 4 are inserted into the insertion holes 601 of the tablet 60. Next, the base end portion 402 of the outer tube 4 and the tablet 60 are heated to melt the tablet 60 (step S6).

Next, after the heating of the tablet 60 or the like is completed, the melted tablet 60 is cooled and solidified to become the glass sealing material 6. And the base end part 402 of the outer tube | pipe 4 is sealed with the glass sealing material 6, and the inside of the outer tube | pipe 4 is interrupted | blocked by the glass sealing material 6 with the exterior. Thus, the sheath thermocouple 11 as the main part of the temperature sensor 1 is manufactured.

(Other manufacturing methods)
Further, the thermocouple 11 can be manufactured without using the sheath pin 12 as follows. First, as shown in FIG. 17, a pair of thermocouple wires 2 are inserted into the inner periphery of the outer tube 4. Next, as shown in FIG. 18, the glass sealing material 6 is filled into the base end portion 402 of the outer tube 4 using the tablet 60. Next, as shown in FIG. 19, the direction of the outer tube 4 is changed so that the glass sealing material 6 is positioned on the lower side, and the insulating material 5 is filled above the glass sealing material 6 in the outer tube 4. . Next, as shown in FIG. 20, the tip portions 201 of the pair of thermocouple wires 2 are fused to form the temperature measuring contact 3. After that, the thermocouple 11 can be manufactured by attaching the tip cover 42 to the tip portion 401 of the outer tube 4.

(Function and effect)
The thermocouple type temperature sensor 1 of this embodiment is a non-grounding type in which the temperature measuring contact 3 is disposed outside the insulating material 5 and in the gas phase K in the tip cover 42 at the tip 401 of the outer tube 4. belongs to. In the thermocouple type temperature sensor 1 which is a non-grounding type, the shortest distance L in the axial direction X from the proximal end 301 of the temperature measuring contact 3 to the distal end surface 501 of the insulating material 5 is in the range of 0 to 0.7 mm. Is set in. As a result, the temperature measuring contact 3 can be arranged outside the insulating material 5 and at a position as close as possible to the insulating material 5.

Therefore, as shown in FIG. 1, a heat transfer path H between the measurement target gas G and the temperature measuring contact 3 can be formed at the position of the base end side X <b> 2 of the temperature measuring contact 3. When the temperature of the measurement target gas G is higher than the temperature of the temperature measuring contact 3, the heat transfer from the measurement target gas G to the temperature measurement contact 3 passes through the outer tube 4 and the pair of thermocouple wires 2. Can be carried out with little or no gas phase K. Further, when the temperature of the temperature measuring contact 3 becomes higher than the temperature of the measurement target gas G, the pair of thermocouple wires 2 and the outside are connected from the temperature measuring contact 3 at the position of the base end side X2 of the temperature measuring contact 3. Heat can be released to the outside of the temperature sensor 1 via the tube 4. As a result, the responsiveness of the thermocouple type temperature sensor 1 which is a non-grounding type can be improved.

Further, since the shortest distance L is in the range of 0 to 0.7 mm, in other words, the shortest distance L is not more than twice the average diameter of the pair of thermocouple wires 2, the tip surface of the insulating material 5 The protruding amount of the tip portion 201 of the pair of thermocouple wires 2 and the temperature measuring contact 3 protruding from 501 can be minimized. Thereby, at the time of use of the temperature sensor 1, the vibration resistance of the front-end | tip part 201 of the pair of thermocouple strand 2 which protrudes from the front end surface 501 of the insulating material 5, and the temperature measuring contact 3 can be improved.

When the shortest distance L exceeds 0.7 mm, the temperature measuring contact 3 is separated from the insulating material 5 and it becomes difficult to improve the responsiveness of the temperature sensor 1. In addition, the pair of thermocouple wires 2 and the temperature measuring contact 3 protruding from the distal end surface 501 of the insulating material 5 may easily vibrate.

In the thermocouple type temperature sensor 1 which is a non-grounding type, the temperature measuring contact 3 is not grounded (not in contact) to the tip cover 42 by a filler or the like. As a result, the linear expansion coefficients of the tip cover 42, the filler, the temperature measuring contact 3, etc. are different from each other at the tip 201 of the pair of thermocouple wires 2 protruding from the tip surface 501 of the insulating material 5. Heat stress hardly acts.

However, in the thermocouple type temperature sensor 1 which is a non-grounding type, the temperature measuring contact 3 does not come into contact with the surroundings but floats in the gas phase K in the tip cover 42. The responsiveness is not excellent. The temperature sensor 1 of the present embodiment improves the demerit that is not excellent in responsiveness while taking advantage of the low thermal stress of the non-grounding type temperature sensor 1.

That is, in this embodiment, a temperature sensor 1 with improved responsiveness while suppressing the occurrence of thermal stress is provided. For this purpose, the shortest distance L from the proximal end 301 of the temperature measuring contact 3 to the distal end surface 501 of the insulating material 5 is set within a range of 0 to 0.7 mm. Then, by forming the heat transfer path H between the measurement target gas G and the temperature measuring contact 3 so as to pass through the tip portions 201 of the pair of thermocouple wires 2, the responsiveness of the temperature sensor 1 is improved. Improved.

On the other hand, as shown in FIG. 21, as a comparative form, in the sheath thermocouple 9 of the conventional non-grounding type temperature sensor, the shortest distance Lx from the base end 301 of the temperature measuring contact 3 to the front end surface 501 of the insulating material 5. Was more than 0.7 mm apart. Therefore, the heat transfer path I between the measurement target gas G and the temperature measuring contact 3 is formed via the tip cover 42 and the gas phase K in the tip cover 42. As a result, while the temperature sensor 1 can be protected from thermal stress, the responsiveness of the temperature sensor 1 cannot be improved.

Thus, the temperature sensor 1 of the present embodiment can greatly improve the responsiveness while being a simple device such as disposing the temperature measuring contact 3 as close as possible to the tip surface 501 of the insulating material 5.

(Confirmation test)
In this confirmation test, the temperature measurement responsiveness of the temperature sensor 1 when the temperature of the measurement target gas G contacting the temperature measurement tip 10 of the temperature sensor 1 is changed from room temperature (25 ° C.) to 600 ° C. confirmed. In this test, a plurality of temperature sensor 1 samples were prepared in which the shortest distance L was appropriately changed around 0.7 mm. In this test, as a response of the temperature sensor 1, when the temperature of the measurement target gas G is changed from room temperature (25 ° C.) to 600 ° C., a change in the temperature of the measurement target gas G is measured. The 63% response time as the time required for the measurement was measured. The 63% response time was defined as the time required for the sensor output to change 63% of the amount of temperature change from 25 ° C. as the initial output to 600 ° C. as the final output.

The result of measuring the 63% response time is shown in FIG. As can be seen from the figure, the 63% response time greatly changes around the vicinity where the shortest distance L is 0.7 mm. When the shortest distance L is 0.7 mm or less, the 63% response time is as short as 4 seconds, and when the shortest distance L is over 0.7 mm, the 63% response time is as long as 8 seconds. It was. Therefore, according to the temperature sensor 1 of the present embodiment in which the shortest distance L is set to 0.7 mm or less, it is a demerit while taking advantage of the strong resistance to thermal stress of the thermocouple type temperature sensor 1 which is a non-ground type. Responsiveness can be improved.

The present disclosure is not limited only to the embodiments, and further different embodiments can be configured without departing from the scope of the disclosure. In addition, the present disclosure includes various modifications, modifications within an equivalent range, and the like.

Claims

A pair of thermocouple wires (2) made of different metal materials;
A temperature measuring junction (3) in which the tips of the pair of thermocouple wires are combined;
An outer tube (4) made of a metal material and accommodating the temperature measuring contact in the tip (401) or in a tip cover (42) attached to the tip;
An insulating material (5) which is made of an insulating material and is disposed in the outer tube, insulates the pair of thermocouple wires from the outer tube, and fixes the pair of thermocouple wires to the outer tube. ) And
The temperature measuring contact is disposed in the gas phase (K) in the tip of the outer tube or in the tip cover,
In the axial direction (X) along the central axis of the outer tube, the shortest distance (L) from the base end (301) of the temperature measuring contact to the distal end surface (501) of the insulating material is 0 to 0.7 mm. A temperature sensor (1) in the range of
The temperature sensor according to claim 1, wherein the base end of the temperature measuring contact is disposed at a position in contact with the distal end surface of the insulating material.
The temperature sensor according to claim 1 or 2, wherein a maximum diameter of the temperature measuring junction is three times or less of an average diameter of the pair of thermocouple wires.
The outer tube has a cylindrical portion (41) having a cylindrical shape, and a tip cover (42) attached to a tip outer peripheral portion of the cylindrical portion,
The temperature sensor according to any one of claims 1 to 3, wherein the distal end surface of the insulating material is within a range of 0 to 0.3 mm from a distal end opening (411) of the cylindrical portion toward a proximal end side. .
The temperature sensor according to any one of claims 1 to 4, wherein the shortest distance is not more than twice an average diameter of the pair of thermocouple wires.