JP3350190B2 - Thermocouple device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermocouple device provided with a sheath-type thermocouple inside a protective outer tube.

[0002]

2. Description of the Related Art For example, a thermocouple device used for measuring an exhaust gas temperature in an aircraft engine is required to withstand severe vibrations and shocks. Therefore, a thermocouple and an insulating powder are placed inside a protective tube made of metal. In some cases, a type in which a sheath-type thermocouple provided with is provided inside a metal protective outer tube is used.

Conventionally, as a thermocouple device of this type, FIG.
And FIG. The structure shown in FIG. 4 is configured as described below. That is, in the drawing, reference numeral 1 denotes a protective outer tube made of metal, and these are closed at the tip. Reference numeral 2 denotes a sheath-type thermocouple, which is provided inside a metal protective tube 3.
The thermocouple element wire 4 and the insulating powder 5 are provided and integrally formed under pressure, and the distal end (detection end side end) of the protective tube 3 is formed to have a small diameter as a tapered portion. The sheath-type thermocouple 2 is inserted into the protective outer tube 1 and
It is directly fitted to.

A plurality of windows 6 are formed at the end of the protective outer tube 1 facing the detection end of the sheath type thermocouple 2, and gas passes through these windows 6 to pass through the inside of the protective outer tube 1. The detection end of the sheath type thermocouple 2 is touched.

FIG. 5 is configured as follows. That is, reference numeral 11 in the drawing denotes a metal protective outer tube, which is closed at the tip. Reference numeral 12 denotes a sheath-type thermocouple, which is formed by providing two thermocouple wires 14 and insulating powder 15 inside a metal protective tube 13 and press-molding the same. Are thinner than the diameter of the protective outer tube 11. The sheath type thermocouple 12 is disposed so as to pass through the inside of the protective outer tube 11 and is supported by a metal support member 16. The support member 16 is supported on the protective outer tube 11 and the protective tube 13 of the sheath-type thermocouple 12 by brazing or the like. A space is provided between the protective outer tube 11 and the sheath-type thermocouple 12.

A plurality of windows 17 are formed at the end of the protective outer tube 11 facing the detection end of the sheath type thermocouple 12, and gas passes through the inside of the protective outer tube 11 through these windows 17. The detection end of the sheath-type thermocouple 12 is touched.

[0007]

However, such a conventional thermocouple device has the following problems. In the thermocouple device having the former configuration, the protective tube 3 of the sheath-type thermocouple 2 is used.
Is directly fitted to the protective outer tube 1, so that the protection tube 3 is filled with the electrical insulation of the protective outer tube 1 and the thermocouple wires 4 of the sheath-type thermocouple 2 from the outside of the protective outer tube 1. Since it is based on the single layer of the insulating powder 5, it is determined by the distance between the thermocouple wire 4 inside the tapered portion of the protective tube 3 and high electrical insulation cannot be secured.

In the thermocouple device having the latter configuration, the space between the sheath-type thermocouple 12 and the protective outer tube 11 is a space and there is no insulating powder, so that the protective outer tube 11 and the sheath-type thermocouple are not present. The electrical insulation of the 12 thermocouple wires from the outside of the protective outer tube 11 cannot be as high as the former.

In the thermocouple device having the latter configuration, the protective tube 13 of the sheath type thermocouple 12 is supported by the support member 14. However, when the thermocouple device is used for measuring the temperature of exhaust gas of a jet engine, for example, it is frequently used. The protective outer tube 11 and the protective tube 13 of the sheath type thermocouple 12 are displaced in the axial direction by thermal expansion due to the temperature of the exhaust gas of the jet engine which changes. In this case, the displacement occurs due to the time difference of the applied temperature and the difference of the coefficient of thermal expansion of the material.
The brazing portion may be repeatedly loaded and may be damaged. As a result, the support of the sheath-type thermocouple 12 becomes unstable, and the thermocouple device breaks down in a short time due to vibration. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a thermocouple device having sufficient electrical insulation and durability, and having excellent reliability.

[0010]

In order to achieve the above object, a thermocouple device according to the present invention comprises a metal protective outer tube, and a thermocouple element wire and an insulating powder provided inside the metal protective tube. A sheath-type thermocouple that is inserted into the inside of the protective outer tube and has a detection end protruding outside from an open end of the protective outer tube;
By providing an insulating powder filled around the sheath-type thermocouple inside the protective outer tube, the durability is improved.
It has been improved .

[0011]

According to the above construction, the insulating powder is provided inside the protective tube of the sheath type thermocouple, and the insulating powder is provided between the protective tube and the protective outer tube. For this reason, the electrical insulation of the sheath type thermocouple to the outside of the protective outer tube in the thermocouple wire is performed by the insulating powder present between the thermocouple wire in the sheath type thermocouple and the protective tube, and furthermore, In addition, it is applied with an insulating powder present between the protective tube and the protective outer tube. That is, electrical insulation of the sheath type thermocouple from the outside of the protective outer tube in the thermocouple wire is provided twice by the insulating powder.

Therefore, the thermocouple device of the present invention has a single insulating powder between a thermocouple wire and a protective outer tube as in a conventional thermocouple device, or a sheath-type thermocouple and a protective outer tube. It has higher electrical insulation than that in which no insulating powder exists.

Further, since the sheath-type thermocouple is supported by the insulating powder filled in the protective outer tube, the protective tube is provided so as to be able to expand, contract, and displace in the axial direction.
Therefore, when the protection tube of the sheath-type thermocouple expands due to external heat, it is possible to expand the protection tube without impairing the support for the protection tube, that is, the support by the insulating powder. Therefore, the support of the sheath-type thermocouple is not unstable due to the expansion of the protection tube, and the durability is excellent.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. In the figure, reference numeral 21 denotes a metal protective outer tube, which forms a cylindrical body whose both ends are open.
Reference numeral 22 denotes a sheath-type thermocouple, which has a diameter smaller than the diameter of the protective outer tube 21, an axial length longer than the axial length of the protective outer tube 21, and has one end (tip) closed. A protective tube 23 made of metal and having a cylindrical shape is provided. Two thermocouple wires 24 are inserted through the inside of the protection tube 23 in the axial direction, and one end (detection end) thereof is joined at the tip of the protection tube 23, and the other end is opened to the protection tube 23. Extending from the opening at the other end. The inside of the protective tube 23 is filled with insulating powder 25 having heat resistance, and the protective tube 23, the thermocouple wire 24 and the insulating powder 25 are pressurized from the outside and integrated.

The protective tube 13 is inserted into the protective outer tube 21 along the axial direction, the distal end extends outward from the distal end opening of the protective outer tube 11, and the base end is the proximal end of the protective outer tube 21. It extends outside from the opening.

Alternatively, as the sheath-type thermocouple 22, a configuration in which only the thermocouple element 24 protrudes outside without opening the tip of the protective tube 13 may be used. Also,
The inside of the protective outer tube 21 is filled with insulating powder 26 having heat resistance. The insulating powder 26 is filled inside the protective outer tube 21 so as to surround the protective tube 23 of the sheath-type thermocouple, and is pressed from the outside together with the protective outer tube 21 to support the protective tube 23.

The base end of the protective outer tube 21 is connected to a flange 27.
, And a terminal box 28 is attached to the flange 27. This terminal box 28 has a pair of terminals 29 to which two thermocouple wires 24 of a sheath-type thermocouple are connected.
Is provided.

Examples of the combination of the materials of the two thermocouple wires 24 in the sheath type thermocouple include platinum-platinum rhodium and aluminum-chromel. Examples of the metal forming the protective tube 23 in the sheath type thermocouple 22 include:
Stainless steel, Inconel, etc.
Examples of the metal forming 1 include stainless steel, Inconel, and Hastelloy.

As the insulating powder 25 filling the inside of the protective tube 23 of the sheath type thermocouple 22, magnesia, alumina or the like can be mentioned. As the insulating powder 26 filling the inside of the protective outer tube 21, magnesia, alumina or the like can be used. Insulating powder 25 filling the inside of these protective tubes 23
The insulating powder 26 filling the inside of the protective outer tube 21 can be freely combined. And a thermocouple wire 24
, The most suitable insulating powder can be selected. For example, when using alumel over chromel as thermocouple element 24 is alumina not preferable when combined with alumel at high temperature, the insulating powder 25 using magnesia, high insulating properties in the insulating powder 26 The use of alumina is considered.

The relationship between the diameter of the protective outer tube 21 and the diameter of the protective tube in the sheath-type thermocouple is as follows, assuming that the diameter of the protective tube is 1. Is 3 to 7. Specifically, the diameter of the protective tube is 1 to 3.
2 mm, and the diameter of the protective outer tube 21 is 4 to 10 mm.

The following method can be used to fabricate this thermocouple device. First, a thermocouple wire and an insulating powder are provided inside the protective tube 23, and the whole is pressurized and integrally formed to manufacture the sheath-type thermocouple 22. The manufactured sheath-type thermocouple 22 is inserted through the inside of the protective outer tube 21 and arranged, and the inside of the protective outer tube 21 is filled with the insulating powder 26.
The protective outer tube 21 and the insulating powder 26 are pressurized to form the whole integrally. Alternatively, the thermocouple wire 24 and the insulating powder 25 are provided inside the protective tube 23, and the protective tube 23 is arranged inside the protective outer tube 21 and filled with the insulating powder 26. Finally, the protective tube 23 and the thermocouple are connected. The wire 24, the insulating powder 26, the protective outer tube 21 and the insulating powder are pressurized to integrally form the whole.

In the thermocouple device configured as described above, the temperature is measured by the gas touching the distal end of the protective tube 23 of the sheath-type thermocouple 22 protruding from the distal end of the protective outer tube 21. For example, since the sheath-type thermocouple 22 is supported by the insulating powder 26 filled in the protective outer tube 21, for example, a thermocouple device used for measuring an exhaust gas temperature in an aircraft engine can withstand severe vibration and impact. Can be. An insulating powder 25 is provided inside the protective tube 23 of the sheath-type thermocouple 22, and an insulating powder 26 is provided between the protective tube 23 and the protective outer tube 21. Therefore, the thermocouple wires 24 of the sheath-type thermocouple 22
Is electrically insulated from the outside of the protective outer tube 21 by the thermocouple wire 24 of the sheath-type thermocouple 22 and the protective tube 23.
And the insulating powder 26 present between the protective tube 23 and the protective outer tube 21. That is, the electrical insulation of the thermocouple wires 24 of the sheath-type thermocouple 22 from the outside of the protective outer tube 21 is provided twice by the insulating powder. Therefore, the thermocouple device of the present invention has a single insulating powder between the thermocouple wire 24 and the protective outer tube 21 like a conventional thermocouple device, or a sheath-type thermocouple 22 and the protective outer tube 2.
1 has a higher electrical insulation property than that in which no insulating powder exists.

The sheath-type thermocouple 22 is connected to the protective outer tube 21.
Is supported by the insulating powder 26 filled therein, so that the protective tube 23 is provided in a state where it can be expanded, contracted and displaced in the axial direction. For this reason, when the protection tube 23 of the sheath-type thermocouple 22 expands due to external heat, the protection tube 23
Can be expanded without impairing the supporting member, that is, the support by the insulating powder 26. Therefore, the support of the sheath-type thermocouple 22 is not unstable due to the expansion of the protective tube 23, and the durability is good.

The present invention is not limited to the embodiments described above, but can be implemented in various modifications. For example, as shown in FIG. 3, in the thermocouple device of the embodiment described above, an end plate 29 formed by melting an insulating material or glass is installed at the end of the proximal end of the protective outer tube 21. The electrical insulation of the strand 24 can be further enhanced.

[0025]

As described above, according to the thermocouple device of the present invention, the electrical insulation of the sheath type thermocouple from the outside of the protective outer tube in the thermocouple wire is made by the thermocouple wire in the sheath type thermocouple. Since the insulating powder existing between the protective tube and the protective tube and the insulating powder existing between the protective tube and the protective outer tube are applied twice, the electrical insulation is very excellent.

The sheath-type thermocouple is supported in a state where it can be expanded, contracted and displaced in the axial direction by insulating powder filled inside the protective outer tube. When the protective tube expands due to external heat, It is very durable because it can be expanded without impairing the support for the protective tube, that is, the support by the insulating powder, and does not destabilize the support of the sheath-type thermocouple. Therefore, according to the present invention, a thermocouple device excellent in reliability can be obtained.

[Brief description of the drawings]

FIG. 1 is an external view showing a thermocouple device according to an embodiment of the present invention.

FIG. 2 is a sectional view showing the thermocouple device of the embodiment.

FIG. 3 is a sectional view showing an example in which the base end of the protective outer tube is closed in the thermocouple device of the embodiment.

FIG. 4 is a sectional view showing an example of a conventional thermocouple device.

FIG. 5 is a cross-sectional view showing another example of a conventional thermocouple device.

[Explanation of symbols]

Reference numeral 21: protective outer tube, 22: sheath type thermocouple, 23: protective tube, 24: thermocouple wire, 25: insulating powder, 26: insulating powder.

Claims (5)

(57) [Claims] 1. A protective outer tube made of metal, and a thermocouple wire and insulating powder are provided inside the protective tube made of metal. The protective tube is inserted into the protective outer tube and has a detection end. A sheath-type thermocouple extending outside from the open end and an insulating powder filled around the sheath-type thermocouple inside the protective outer tube have improved durability. > A thermocouple device characterized by that. 2. The method according to claim 1, wherein the liquid crystal is used for an aircraft engine.
The thermocouple device according to claim 1. 3. A method for measuring exhaust gas temperature.
The thermocouple device according to claim 1 or 2, wherein
Place. 4. The insulating powder is made of magnesia or aluminum.
4. The method according to claim 1, wherein
A thermocouple device according to claim 1. 5. The thermocouple wire inside the protection tube.
The insulating powder provided is magnesia;
Filled around the sheath type thermocouple inside the outer tube.
Wherein the insulating powder is alumina.
5. The thermocouple device according to any one of 1 to 4.