Thermocouple for pilot burners
United States Patent 2438575

This invention relates to a thermocouple structure, and more particularly to a structure of this character that may be used to generate a controlling electric current by the aid of a burner flame. The generation of electrical energy is effected by joining a pair of dissimilar conductors, and...

Ray, William A.
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US Patent References:
2339809Thermocouple structure1944-01-25
2318822Lead connector1943-05-11
2267742Thermocouple and pilot burner1941-12-30


This invention relates to a thermocouple structure, and more particularly to a structure of this character that may be used to generate a controlling electric current by the aid of a burner flame.

The generation of electrical energy is effected by joining a pair of dissimilar conductors, and heating the joint or junction above that of other ends of the conductors. The power generated is a function of the difference in temperature at the hot junction and at the cold junctions. The hot junction, for the control purposes, is disposed in the burner flame. By appropriate shielding, the cold junction temperatures can be maintained considerably below that of the hot junction.

Thermocouples adapted to this purpose are now well known. As thermoelectric conductors, use is often made of Chromel and Copel, which are joined to form the hot junction. The other ends of the conductors are connected in any appropriate manner to appropriate leads, and these joints are the cold junctions.

It is one of the objects of this invention to improve thermocouple structures of this character.

It is another object of this invention to provide a structure that is simple and inexpensive to manufacture.

In order to shield the cold junctions from the burner flame, it has been proposed to use a sheath surrounding the cold junctions. In this way, the cold junctions can be placed quite close to the hot junction, with an attendant saving in the length of the thermoelectric conductors. It is another object of this invention to make it possible in a simple manner to provide a shield for at least one of the cold junctions, and which serves as well to support the conductors in a simple manner.

Referring to the drawings: Figure 1 is a view, mainly in longitudinal section, of the thermocouple structure incorporating the invention; Fig. 2 is a side elevation thereof; and Figs. 3, 4, 5, and 6 are enlarged sectional views, taken along correspondingly numbered planes of Fig. 1.

Two dissimilar conductors are employed to form a thermoelectric couple.

One of these conductors has a head portion I through which an aperture 2 is formed. Attached to the head portion I is a hollow extension that includes the narrow portion 4. The head I is quite long, providing a long aperture 2.

This conductor, including its extensions 4 and 5, may be formed, for example, of Chromel.

Another thermoelectric conductor 6 (which may be Copel) is provided, one end of which extends into the aperture 2, thus forming a hot junction. In order to ensure intimate electrical contact between the two conductors I and 6, the upper end of conductor I may be originally formed with a beveled projection 1, as indicated in dotted lines. This beveled projection may extend beyond the upper end of the conductor 6 and may be melted down to form a fused joint over the top of conductor 6.

The Copel conductor 6 is adequately supported, due to the fact that the end accommodated in the aperture 2 is quite long. Furthermore, it is shown as provided with an appropriate heat resisting insulation layer 8 formed, for example, of asbestos (see also Figs. 4 and 5). It is joined to a copper lead member 9, as by the aid of a split metallic sleeve 10, which engages the bared ends of the conductor 6 and the lead 9. This band 10 may be brazed, or otherwise firmly joined, to the contiguous ends of the conuductor 6 and lead 9.

The extension 5 is telescoped over a hollow connector II, thereby providing an electrical connection to a lead 12. This electrical connection forms one of the cold junctions; the other cold 0junction is formed between contiguous ends of the conductor 9 and the conductor 6 connected by the band or sleeve 10.

A flexible armor 13, formed of convoluted metal, is preferably disposed over the lower end of the conductor 6, as well as over the leads 9 and 12. This armor may extend upwardly into the lower end of the connector I . This connector I, as shown most clearly in Fig. 2, may be pinched as illustrated at 14 to hold the flexible armor 13 tightly in place within the member 11.

As shown most clearly in Fig. 4, the hollow extension 5 which forms a.skirt portion, as well as the upper end of the hollow connector II, may be crimped to engage the lead 12 quite firmly. In this way, the lead 12 is adequately supported and is in good electrical contact with the interior of the hollow connector II.

In use, the head I is intended to be inserted into a pilot flame; thereby the hot junction is heated. The skirt portion 4, 5 shields the cold junctions from the flame and ensures that a large temperature differential can be maintained between the hot junction and the cold junctions. As clearly shown in Figs. 1 and 6, a sleeve 15 of insulating material surrounds the band 10, insulating the band 10 from the armor 13.

The inventor claims: In a thermocouple structure: a first thermoelectric conductor having an aperture adjacent one end and a hollow extension at the other end; a second thermoelectric conductor disposed in the hollow extension and having an end inserted into the aperture; a hollow connector telescoping into the hollow extension; a lead connected to the interior of said connector; a layer of insulation on said second conductor; and a flexible armor encompassing the said lead and the second conductor; said hollow extension and the hollow connector being formed to hold the said lead firmly in relation to the connector.


REFERENCES CITED The following references are of record in the file of this patent: 'UNITED STATES PATENTS Name Date Mantz --------- Dec. 30, 1941 Wantz ---------- May 11, 1943 Ray ------------- Jan. 25, 1944 I I