JP2728359B2 - thermocouple - 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 in which a linear internal electrode is disposed inside a shell-shaped external electrode.

[0002]

2. Description of the Related Art As a thermocouple having a structure excellent in response and durability, a lead pipe forming one lead, a shell-shaped external electrode brazed to the end of the lead pipe, and a A thermocouple comprising an internal electrode welded to the inner wall of the tip is manufactured, and is used for detecting a misfire of a gas appliance such as a gas stove. Conventionally, a thermocouple having this structure is known in which a portion having a large inner diameter is formed at the tip of a lead pipe, a rear end of a conical shell-shaped external electrode is inserted into the large inner diameter, and a fitting portion is brazed. It is.
(Japanese Patent Publication No. 3-69029)

[0003]

It is desirable that the shell-shaped external electrode and the lead pipe can be easily and accurately assembled, and that the brazing solder flows smoothly and quickly on the fitting surface. An object of the present invention is to provide a thermocouple in which a fitting portion between a shell-shaped external electrode and a lead pipe is brazed.
An object of the present invention is to provide a thermocouple that can easily and accurately assemble the two and that can perform brazing surely and quickly.

[0004]

According to the present invention, there is provided a lead pipe forming one lead, and an external electrode formed of a shell-like thermocouple material and fixed to a tip of the lead pipe. And an inner electrode formed of the other thermocouple material and welded to the inner wall at the tip of the outer electrode, and the rear end of the outer electrode is fitted around the outer periphery of the tip of the lead pipe. In a thermocouple brazed with a mating surface, a stepped diameter small portion is formed at the tip of the lead pipe, and a plurality of axial cutouts or protrusions are formed on the rear end surface of the external electrode over the circumferential direction, The rear end of the external electrode is externally fitted to the small stepped diameter portion and the fitting surface is brazed.

[0005]

[0006]

According to the present invention, a plurality of notches or projections are formed on the rear end face of the external electrode in the circumferential direction, and a stepped small portion is formed at the front end of the lead pipe to which the rear end of the external electrode is fitted. Is formed, the two can be easily and accurately assembled, and the brazing material can be quickly and smoothly penetrated into the fitting surface. Therefore, the brazing operation can be performed smoothly and reliably.

[0007]

[0008]

1 shows a misfire sensor 100 for a gas stove. The misfire sensor 100 includes a thermocouple 1 according to the present invention, an outlet 2 for connection to a control device, and a conducting wire 3 connecting the thermocouple 1 and the outlet 2. As shown in the enlarged view of FIG. 2, the thermocouple 1 has a lead pipe 4 forming one lead, and a pipe-shaped tip welded to the tip of the lead pipe 4 and formed by narrowing the tip to a small diameter. An external electrode 5 having a conical shell shape and made of Inconel 600, which is one thermocouple material. At the center of the inner wall surface at the tip of the outer electrode 5, an inner electrode 6 having a linear shape and formed of constantan, which is the other thermocouple material, is welded.

The conducting wire 3 includes an external conducting wire 31 made of an electric soft copper wire welded to the outer periphery of the rear end of the lead pipe 4 and a fluororesin copper ply wire with a varnish glass tube 32 welded to the rear end of the internal electrode 6. And an internal conductor 33 composed of The rear end of the external conductor 31 is the outlet 2
The internal conductor 33 is inserted through the lead pipe 4 and guided backward, and the rear end is connected to the terminal 22 of the outlet 2. For the outer conductor 31 and the inner conductor 33, a clad material in which the outer periphery of an iron core is covered with a body is used. In addition, the inner conductor 33 may be formed by coating a soft copper wire for electricity.

The lead pipe 4 has a small diameter portion 41 with a step 40 formed on the outer periphery of the leading end. The rear end of the external electrode 5 is fitted to the small diameter portion 41 and the rear end face 51 is in contact with the step 40. And a brazing 7 is applied to the fitting surface. External electrode 5
At the rear end face 51, two or more axial notches 52 (see FIGS. 2 and 3) are formed in the circumferential direction, so that the brazing material melted during the brazing operation has a gap between the step 40 and the notches 52. From above, it is possible to smoothly enter the fitting surface. Instead of the notch 52, a configuration having a plurality of axial projections 53 as shown in FIG. The internal electrode 6 is welded to the tip of the internal conductor 33 at a position intermediate between the external electrodes to form the cold junction 11.

As shown in FIG. 1, the misfire sensor 100 is installed and used so that an external electrode 5 of a thermocouple 1 contacts a flame F of a gas stove. The amount of Inconel 600 used as the material of the external electrode 5 can be reduced. When the external electrodes 5 are mass-produced by drawing, the processing of the external electrodes 5 can be facilitated by reducing the axial dimension of the external electrodes 5.

FIGS. 3 and 4 show a method of manufacturing the thermocouple 1. FIG.
It will be explained together. As shown in FIG. 3A, a brass lead pipe 4 having a small-diameter portion 41 provided on the outer periphery of the tip is arranged upright. The pipe made of Inconel 600 is cut into a predetermined length or drawn from a plate material to form a small-diameter pipe-like portion 54 at the end and to form a conical shell shape (substantially shell shape) to form the external electrode 5. It is manufactured, and a plurality of notches 52 or projections 53 are provided on a rear end (lower end in the figure) surface 51 in the circumferential direction. Next, as shown in FIG. 3B, the rear end of the external electrode 5 is externally fitted to the small diameter portion 41, and the fitting surface is brazed with silver solder.

Next, as shown in FIG. 4D, a welded body obtained by welding the internal electrode 6 having a small diameter at the distal end to the distal end of the internal conductor 33 is inserted into the distal end of the internal conductor 33 from below. Are set to be slightly retracted from the tip of the pipe-shaped portion 54. In this state, the tip of the pipe-shaped portion 54 and the tip of the internal electrode 6 are TIG- welded as shown in FIG.
Further, the outer conductor 31 is welded to the outer periphery of the rear end of the lead pipe 4, and the outlet 2 is connected to the rear ends of the outer conductor 31 and the inner conductor 33.

In this thermocouple, the outer electrode 5 and the inner electrode 6 are made of Inconel 600 and inexpensive constantan, which are excellent in heat resistance and corrosion resistance at high temperatures, but other thermocouple materials can be used. It is. The welding between the tip of the external electrode 5 and the pipe-shaped tip of the internal electrode 6 can be plasma welding or laser welding other than TIG welding.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a thermocouple.

FIG. 2 is a sectional view of a misfire sensor.

FIG. 3 is a perspective view for explaining a manufacturing process of the thermocouple.

FIG. 4 is a perspective view for explaining a manufacturing process of the thermocouple.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermocouple 2 Outlet 3 Conductor 4 Lead pipe 5 External electrode 6 Internal electrode 7 Brazing 31 External conductor 33 Internal conductor 41 Small diameter part 52 Notch 53 Projection 54 Pipe part 100 Misfire sensor

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Haruyuki Morii 2-26 Fukuzumi-cho, Nakagawa-ku, Nagoya-shi Inside Linnai Co., Ltd. (72) Inventor Yoshitaka Tamada 665-1, Shimomohata, Honjo, Komaki City, Aichi Prefecture Rinnai Seiki Co., Ltd. (72) Inventor Kenichi Inagaki Komaki City, Aichi Prefecture, Honjo, Shimomohata 665-1 Rinnai Seiki Co., Ltd. (56) References JP-A-53-112241 (JP, A) 51-151961 (JP, U) Fully open 1975-71882 (JP, U) Fully open 1974-135586 (JP, U)

Claims (1)

(57) [Claims] 1. A lead pipe forming one lead, an external electrode formed of a shell-like thermocouple material and fixed to a tip of the lead pipe,
An inner electrode formed of the other thermocouple material and welded to the inner wall at the tip of the external electrode, and the rear end of the external electrode is fitted around the outer periphery of the tip of the lead pipe. In a thermocouple whose surface is brazed, a small stepped diameter portion is formed at the tip of the lead pipe, and an axial cutout or protrusion is formed in a rear end surface of the external electrode in a circumferential direction.
And the external electrode is formed on the small stepped portion.
Thermocouple with the rear end fitted externally and the fitting surface brazed.