US2278744A - Method of forming thermocouples - Google Patents

Description

April 1941 H. T. SPARROW ET AL 2,278,744

METHOD OF FORMING THERMO-COUPLES Filed May 15, 1940 inventor Hubert T. Sparrow- J 614.14. M. Wi l s on.-

attorney,

Patented Apr. 7, 1942 METHOD OF FORWNG THERMOCOUPLES I Hubert T. Sparrow and John M. Wilson, Minneapolis, Minn, assignors to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn, a corporation of Delaware Application May 13, 1940, Serial No. 334,812

9 Claims.

The present invention is concerned with a new and novel thermo-couple unit and particularly with a novel method of making the same.

A thermo-couple is composed of a pair of metals having dissimilar thermo-electric characteristics, which metals are permanently joined at one end to form a hot junction and are adapted to be electrically joined at the other end to form a cold junction. Where a plurality of thermo-couples are employed, the device is known as a thermopile. Thermo-couples are usually relatively expensive to construct and this is particularly true in the case of thermopiles. The present invention has as its object the provision of a thermo-couple which can be formed with a relatively simple process and is particularly concerned with the process of making the same.

The present invention accomplishes this object by providing a thermo-couple in the form of a flat member which can be formed by a plurality of cutting operations. These cutting operations may if desired be accomplished by stamping. The various units are formed from a long strip composed of a plurality of component strips of dissimilar metals secured together along their longitudinal edges, this strip being cut transversely at spaced points to provide a plurality of relatively short sections. The material along the joints between the component strips of each sec- 111 tion is then cut away for the greater portion of the length of the strips to provide series connected thermo-couple members. The resulting unit may then be rolled, if desired, to provide a more compact arrangement.

For a more complete understanding of the invention, reference is made to the accompanying specification, claims and drawing of which:

Figure l is a perspective view of the strip from which the individual sections are cut;

Figure 2 is a view of one individual section of the strip with dotted lines to indicate where the material is cut away;

Figure 3 is a perspective view of one form of the completed thermo-couple device; and

Figures 4 and 5 are perspective views of modified forms of our device.

The first step in the novel process of the present invention is to form a strip comprising a plurality of pairs of metallic strips, each pair comprising two strips of dissimilar thermo-electric characteristics, said strips all being joined along their longitudinal edges. As previously indicated, this strip is shown in Figure 1. Referring to this figure, the strip itself is designated one desirable method is to roll these members together while hot so as to weld them together in the rolling process. If the members are formed by such a rolling process, it is possible to have the strip Ill in the form of a continuous strip.

At uniformly spaced points designated by the dotted lines l8 and IS, the strip I0 is cut transversely to the length thereof to provide a plurality of short sections. One of these sections I is shown in Figure 2 and is designated by the reference character 20.

The last step in the formation of one form of the thermopile is to remove material adjacent the joints to electrically separate the component strips for the greater portion of their length. The dotted lines 22 and 23 enclose the areas cut away along the joints between strips l2 and i3 and between strips [4 and I5. It will be noted that by cutting away this portion two slots are provided separating the strips l2 and 13 on the one hand and strips M and IS on the other hand for the greater portion of the length of these strips. A dotted line 24 encloses the portion which is cut out adjacent one end of the section and which is cut out between strips II and l2, l3 and M, and i5 and I6. It will be noted that between strips H and l2, l3 and I4, and i5 and IS the dotted lines extend within a short distance of the far end of section 20. The dotted line 24 further encloses a rectangular piece extending from the near end of its strip to the portion 28 of dotted line 24. It will be noted that this rectangular portion includes the near ends of strips l2, l3, I4 and I5 leaving a portion of strips II and I6 projecting outwardly from the remaining portion of section 20. The dotted lines 29 and 30 enclose circular portions to provide apertures through the projecting ends of strips II and IS.

The particular manner in which the portions outlined in dotted lines are removed forms no part of the present invention although it is to be understood that such material can be removed by a single die stamping operation, using dies of relatively simple form.

In Figure 3 one form of the completed product is shown. The slots formed by cutting away the portion enclosed by dotted lines 22 and 23 are designated in this figure by reference numerals 32 and 33. The slots between members I l and l2, l3 and I4, and I5 and it are designated by the reference numerals 35, 86 and 81, respectively. It will be noted that alternate slots extend from opposite ends of the section. The result is that strips H to IE are connected together in series by the remaining uncut portions of the joints between these strips. It is usually desirable, where a plurality of thermo-couples are employed, to connect them in series as is done by extending alternate slots in alternate directions in the manner shown. It is also possible to connect the constituent thermo-couples in parallel by extending the slots in the same direction and providing suitable jumpers to connect the various elements together.

The projecting ends of strips II and [6 are designated in Figure 3 by the reference characters 40 and 4 I the apertures therethrough formed by the removal of the material within dotted lines 29 and 30 being designated by the reference numerals 42 and 44. It will be noted that the projecting ends 40 and 4| have been bent upwardly. These ends are designed to form terminalportions for the'thermopile unit and may if desired also be employed for maintaining the unit. The apertures 42 and 44 may be tapped so as to provide for the receptionof screws therein.

The device of Figure 4 is similar to Figure 3 with the exception that after the portions between the component strips are cut away, the strip is subjected to a rolling operation. It will be noted that in this species, the terminals 50 and 5| corresponding to terminals 40 and ll of Figure 3 are not bent transversely to the strip but merely extend longitudinally therefrom. The

-form of Figure 4 is desirable where the burner is of the conventional type with a flame of substantially circular cross-section.

In Figure 5 there is shown a still further modiflcation of our device. In this form of the device, there are a relatively large number of component strips so as to provide a large number of thermocouple units. The strip itself is of considerably greater width than in the species of Figures 1 to 4 and is preferably of somewhat thinner material. After the strip is subjected to the stamping operation indicated in dotted lines in Figure 2, the strip has a layer of insulating material disposed adjacent it and is rolled spirally to form the compact unit shown in Figure 5. In this figure, the insulating layer is designated by the reference numeral 54. It will be noted that in the form shown, there are twelve thermocouples and in spite of this, the space occupied is not particularly greater than that occupied by the species of Figure 4. The device does have the disadvantage however over that of Figures 3 and 4 in that a somewhat greater time is required for cooling of the hotjunction of the thermocouples due to the fact that they are closer together and hence radiate the heat more slowly. Where the time of response is not of theutmost importance however, the arrangement of Figure 5 is desirable by reason of its relative compactness.

It will be seen that by reason of the present invention, it'is possible to manufacture thermocouples or thermopiles by an extremely simple process. While we have shown a specific embodiment of our invention, it is to be understood that the scope thereof the appended claims.

We claim as our invention:

1. The method of forming thermo-electric devices which comprises the steps of assembling a. plurality of strip members in side by side relation and in which the strips adjoining any one strip have thermo-electric characteristics dis-- similar from the thermo-electric characteristics of said one strip, heating and rolling the said strip members to join them along their longitudinal. side edges to the adjacent strip members to form a sheet of material, cutting said sheet trans versely to provide a plurality of relatively short sections, separating adjacent strips for the greater portion of the length of each section by removing material from along each joint, the separation of the strips along adjacent joints extending from opposite ends of the section and the resulting structure being a continuous strip in which members having dissimilar thermoelectric characteristics are joined in series with alternate joints at one end of said sheet of material.

2. The method of manufacture of'a thermocouple device comprising the steps of forming a strip of material composed of a plurality of monometal strip members joined in edgewise relation, the alternate strip members having predetermined thermo-electric characteristics and adjacent strip members having dissimilar thermoelectric characteristics, heating the said strip members and joining them while so heated in said side by side relation to form said strip of material, separating the strip members along and for the greater portion of the length of each joint by removing material from along each joint, the said separation along adjacent joints extending to opposite ends of said strip of material to form the strip members into a continuous series in which a member is connected to members having dissimilar thermo-electric characteristics with alternate joints located at one end of said strip of material.

3. The method of manufacture of a thermocouple device comprising the steps of forming a is to be limited only by strip ofmaterial composed'of a plurality of monometal strip members joined in edgewise relation, the alternate strip members having predetermined thermo-electric characteristics and adjacent strip members having dissimilar thermoelectric characteristics, heating the said strip members and joining them while so heated in said side by side relation to form said strip of material, separating the strip members along and for the greater portion of the length -of each 4. The method of manufacture of a thermocouple device comprising the steps of forming a strip of material composed of a plurality of monomined thermo-electric characteristics and adjacent strip members having dissimilar thermoelectric characteristics, heating the said strip members and joining them while so heated in said side by side relation to form said strip of material, separating the strip members along and for the greater portion of the length of each joint by removing material from along each joint. the said separation along adjacent joints extending to opposite ends of said strip of material to form the strip members into a continuous series in which a member is connected to members having dissimilar thermo-electric characteristics with alternate joints located at one end of said strip of material, and bending said strip of material about an axis longitudinal of the said strips.

5. The method of manufacturing a composite metal strip employed in the manufacture of thermo-electric devices comprising, the steps of assembling in side by side relation a plurality of mono-metal strip members and in which the members adjacent to any one ofthe members have thermo-electric characteristics dissimilar to those of said one member and with alternate members having similar thermo-electric characteristics, heating the said plurality of strip members, and rolling the said members while hot to weld the strips together along the longitudinal side edges of adjacent strips to form a composite metal strip for use in the manufacture of thermoelectric devices.

6. The method of manufacturing thermo-electric devices from a composite metal strip comprising a plurality of mono-metal strip members joined along their longitudinal side edges, the

7 adjacent members of said strip having dissimilar thermo-electric characteristics and alternate members having similar thermo-electric characteristics, the steps comprising separating said members for the greater portion of the length of each joint by removing metal from along each joint, the metal removed from one joint extending to one end of said strip and the metal removed from the adjacent joints extending to the opposite end of said strip to thus form a single continuous strip in which the component strip members are connected in series with alternate connecting joints extending to one edge of said strip.

'7. The method of manufacturing thermo-electric devices from a composite metal strip comprising a plurality of mono-metal strip members joined along their longitudinal side edges, the adjacent members of said strip having dissimilar thermo-electric characteristics and alternate members having similar thermo-electric characteristics, the steps comprising separating said members for the greater portion of the length of each joint by removing metal from along each joint, the metal removed from one joint extend ing to one end of said strip and the metal removed from the adjacent joints extending to the opposite end of said strip to thus form a single continuous strip in which the component strip members are connected in series with alternate connecting joints extending to one edge of said strip and removing material from between the separated endsrof the outermost strips to provide electrical terminals for said thermo-couple device consisting of the extended and separated ends of said outermost strips.

8. The method of manufacturing thermo-electric devices from a composite metal strip comprising a plurality of mono-metal strip members joined along their longitudinal side edges, the adjacent members of saidwstrip having dissimilar thermo-electric characteristics and alternate members having similar thermo-electric characteristics, the steps comprising separating said members for the greater portion of the length of each joint by removing metal from along each joint, the metal removed from one joint extending to one end of said strip and the metal removed from the adjacent joints extending to the opposite end of said strip to thus form a single continuous strip in which the component strip members are connected in series with alternate connecting joints extending to one edge of said strip and bending said strip of material about an axis longitudinal of the said strips.

9. The method of manufacturing thermo-electrio devices from a composite metal strip comprising a plurality of mono-metal strip members joined along their longitudinal side edges, the adjacent members of said strip having dissimilar thermo-electric characteristics and alternate members having similar thermo-electric characteristics, the steps comprising separating said members for the greater portion of the length of each joint, the separation of one. joint extending to one end of said strip and the separation of the adjacent joints extending to the opposite end of said strip to thus form a single continuous strip in which the component strip members are connected in series with alternate connecting joints extending to one edge of said strip, bending the said strip of material about an axis longitudinal of the said strips to form a roll; and adding insulating material between adjacent layers of the thus formed roll.

HU'BERT T. SPARROW.

JOHN M. WILSON.

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