JP2000131150A - Thermocouple - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid the deterioration of a metal wire to improve durability by filling alumina powder in the gap between the inner surface of a protective inner pipe and an insulation pipe and through-holes of the insulation pipe to suppress a hot gas from entering the protective inner pipe. SOLUTION: Metal wires 15 are inserted in through-holes, and each end 15a exposed about 5 mm long from an insulation pipe 12 is welded to one end 16a of a thermocouple metal wire 16 of 0.5 mm (large diameter). The through-holes of the insulation pipe 12 and the gaps among the metallic wires 15, an inner surface 11a of an inner pipe 11 and the insulation pipe 12 are filled with alumina powder 18. A filler 19 of epoxy resin, etc., is filled from the opening 11b of the inner pipe 11 so as to seal the opening 11b, including the connections of the metal wires 15, 16 and the other ends of the metal wires 16 exposed from the opening 11b of a reduced thermocouple 10 are connected to the output terminals of a terminal box. An opening end of a protective outer pipe for covering and sealing the outside of the thermocouple 10 is inserted in a mounting hole of a stem of the terminal box to fix the outer pipe.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermocouple for measuring a temperature using a thermoelectromotive force.

[0002]

2. Description of the Related Art As shown in FIG. 4, a conventional general thermocouple has a pair of through-holes formed through an insulating tube a and has a pair of through holes formed of "platinum and platinum rhodium" for a thermocouple metal wire. b, and the other end b ′ of the thermocouple metal wire b having a constant thickness (usually 0.5 mm in diameter) at the cold junction side is connected to the output terminal e of the terminal box c.
And a protective tube f that covers the insulating tube a so as to hermetically seal the insulating tube a is fixed to a base d of the terminal box c.

[0003]

In the above-described conventional thermocouple, since the gap between the inner surface of the protective tube f and the inner insulating tube a is not filled, for example, a ceramic furnace, a melting furnace, etc. Atmosphere gas during the temperature measurement of
It easily penetrates into the inside, and the atmospheric gas causes deterioration of the thermocouple metal wire b. When the thermocouple is installed and used in the vertical direction, the weight load of the insulating tube a always acts on the high-temperature end of the thermocouple metal wire b, and the thermocouple is easily damaged. This was a factor that hindered the durability of the device. Further, since the thermocouple metal wire b is made of a material such as "platinum and platinum rhodium" having a large diameter of 0.5 mm and a large diameter, the manufacturing cost is high.

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermocouple in which the deterioration of a metal wire for a thermocouple due to an atmospheric gas during temperature measurement is prevented as much as possible to improve the durability and reduce the manufacturing cost. It is in.

[0005]

In order to achieve the above object, according to the first aspect of the present invention, an insulating tube in which small-diameter thermocouple metal wires are inserted into a pair of through holes, respectively, is hermetically sealed. Alumina powder is inserted into the protective inner tube to fill the through hole with the metal wire for the thermocouple, and the gap between the inner surface of the protective inner tube and the insulating tube, and the metal for the thermocouple having a small diameter exposed from the insulating tube. One end of a large-diameter thermocouple metal wire is connected to each end of the wire, and a rejuice thermocouple body in which the opening of the protective inner tube is sealed with a filler is provided. The other end of the exposed large-diameter thermocouple metal wire was connected to the output terminal of the terminal box, respectively, and the protective outer tube that covered the resin juice thermocouple so as to hermetically sealed was fixed to the base of the terminal box. It is characterized by.

In order to achieve the same object, the invention described in claim 2 is to insert an insulating tube having a small-diameter thermocouple metal wire inserted into a pair of through holes into a protective tube having a closed end. Alumina powder is filled into the through hole, the thermocouple metal wire, and the gap between the inner surface of the protective tube and the insulating tube, and a large diameter is provided at each end of the small-diameter thermocouple metal wire exposed from the insulating tube. One end of each of the diameter metal wires for thermocouples is connected to each other, and a rejuice thermocouple body in which an opening of the protective tube is sealed with a filler is provided, and a large-diameter thermocouple exposed from the opening is provided. The other ends of the metal wires are connected to output terminals of a terminal box, respectively, and the resin juice thermocouple is fixed to a base of the terminal box.

[0007]

Since the gap between the inner surface of the protective inner tube (or the protective tube) and the insulating tube and the through-hole of the insulating tube into which the thermocouple metal wire is inserted are filled with alumina powder, At the time of temperature measurement, high-temperature atmospheric gas is suppressed from entering the protective inner tube. Therefore, deterioration of the thermocouple metal wire due to the atmospheric gas is prevented as much as possible.
Further, when the thermocouple of the first aspect is installed and used in the vertical direction, the weight load of the rejuice thermocouple acts on the other end of the thermocouple metal wire on the cold junction side. Since the strength of the other end does not decrease due to the heating of the atmospheric gas, the durability of the thermocouple metal wire is improved.

In the case where the thermocouple of the second aspect is installed and used in a vertical direction, the thermocouple body is fixed to the base of the terminal box, so that the thermocouple is attached to the other end of the metal wire for the thermocouple. Body weight load does not work. Since this thermocouple is configured to be small in size without the protective outer tube of claim 1, it is suitable for use in a small measuring place.

[0009] In any of the above-mentioned thermocouples, a small diameter dimension (diameter 0.
(3 mm) thermocouple metal wire, which is connected by welding to a large-diameter (0.5 mm diameter) thermocouple metal wire near the opening of the thermocouple body. Compared with a conventional thermocouple using a size, the material cost of an expensive metal wire such as “platinum and platinum rhodium” is reduced by about 3%.
It can be reduced by about 0%.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal side view of a thermocouple,
FIG. 2 is a cutaway side view of the Rejuice thermocouple, and FIG. 3 is a longitudinal side view of the Rejuice thermocouple.

A protective outer tube 20 is fixed to the base 2 of the terminal box 1 of the thermocouple T shown in FIG. The alumina protective inner tube 1 in which the tip of the rejuice thermocouple body 10 is sealed
As shown in FIG. 2 and FIG.
3 and an alumina insulating tube 12 provided with a slit groove 14 in the longitudinal direction of the tip is inserted.

Reference numeral 15 denotes a thermocouple metal wire having a diameter of 0.3 mm (small diameter) made of a material such as "platinum and platinum rhodium". The metal wires 15 are inserted into the through holes 13 respectively. A diameter of 0.5 mm (large diameter dimension) is provided at each end 15a exposed by a length of about 5 mm from the insulating tube 12.
One end 16a of each of the thermocouple metal wires 16 is connected by welding. Then, alumina powder 18 is filled into the through hole 13 of the insulating tube 12 and the metal wire 15 for the thermocouple, and the gap between the inner surface 11 a of the protection inner tube 11 and the insulating tube 12. Further, by filling a filler 19 such as an epoxy resin from the opening 11b of the protective inner tube 11, the opening 11b is sealed including the connecting portions of the metal wires 15 and 16 for the thermocouple (FIG. 2, FIG. 3). Thus, the rejuice thermocouple body 10 is configured.

The opening 11 of the above-mentioned rejuice thermocouple body 10
b, the other ends 16b, 16 of the thermocouple metal wires 16 exposed from
b is connected to the output terminals 5 and 6 of the terminal box 1, respectively. The opening end 20a of the protective outer tube 20 for covering the rejuice thermocouple body 10 from the outside is inserted into the mounting hole 3 of the base 2 of the terminal box 1, and the protective outer tube 20 is fixed. I do. As described above, the thermocouple T of the present invention is configured.

For a small thermocouple suitable for use in a small measuring place, a component corresponding to the protective outer tube 20 of the thermocouple T is omitted, and a similar Rejuice thermocouple is used in the terminal box. It is constituted by fixing directly to the base.

According to the above-described thermocouple of the present invention, the deterioration of the thermocouple metal wire due to the high-temperature atmosphere gas during temperature measurement is prevented as much as possible, and the strength of the supporting portion of the thermocouple metal wire is prevented. Since no decrease occurs, the durability can be significantly improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal side view of a thermocouple.

FIG. 2 is a cutaway side view of a rejuice thermocouple body.

FIG. 3 is a longitudinal sectional side view of a rejuice thermocouple body.

FIG. 4 is a longitudinal side view of a conventional thermocouple.

[Explanation of symbols]

T → thermocouple 1 → terminal box 2 → base 5,6 → output terminal 10 → rejuice thermocouple body 11 → protective inner tube 11a → inner surface 11b → opening 12
→ Insulation tube 13 → Hole 15 → Metal wire for small diameter thermocouple 16 → Metal wire for large diameter thermocouple 16a → One end 16
b → the other end 18 → alumina powder 19 → filler 20 → protection outer tube

Claims (2)

[Claims] An insulating tube in which small-diameter metal wires for thermocouples are inserted into a pair of through holes is inserted into a protective inner tube having a sealed end, and the through holes, the metal wires for thermocouples, and the protection tubes are inserted. A gap between the inner surface of the inner tube and the insulating tube is filled with alumina powder, and one end of the large-diameter thermocouple metal wire is connected to each end of the small-diameter thermocouple metal wire exposed from the insulating tube. And a rejuice thermocouple body having an opening of the inner protective tube sealed with a filler, and the other end of the large-diameter thermocouple metal wire exposed from the opening is connected to an output terminal of a terminal box. And a protective outer tube which is connected to the terminal box and covers the Rejuice thermocouple so as to hermetically seal the thermocouple. 2. An insulating tube in which small-diameter thermocouple metal wires are inserted into a pair of through holes, respectively, is inserted into a protective tube having a closed end, and the through hole, the thermocouple metal wire, and the protective tube are inserted. Filling the gap between the inner surface of the insulating tube and the insulating tube with alumina powder, connecting one end of the large-diameter thermocouple metal wire to each end of the small-diameter thermocouple metal wire exposed from the insulating tube, Providing a rejuice thermocouple body in which the opening of the protective tube is sealed with a filler, and connecting the other ends of the large-diameter thermocouple metal wires exposed from the opening to the output terminals of the terminal box, respectively. A thermocouple, wherein the thermocouple body is fixed to a base of the terminal box.