US2416455A

US2416455A - Thermoelectric generating device

Info

Publication number: US2416455A
Application number: US533511A
Authority: US
Inventors: William A Ray
Original assignee: General Controls Co
Current assignee: General Controls Co
Priority date: 1944-05-01
Filing date: 1944-05-01
Publication date: 1947-02-25
Anticipated expiration: 1964-02-25

Description

Feb. 25, 1947. w RAY THERMOELECTRIC GENERATING DEVICE Filed May 1, 1944 hJulaZzTa/z 2 3noentor: WILL/AM A. PA Y,

Psamd Feb. 25, 1941 THERMOELECTRIC GENERATING DEVICE William A. Ray, Los Angeles, Calif., or to General Controls 00., acorporation Application May 1, 1944, Serial No. 533,511

4 Claims.

September 12, 1941; now Patent No. 2,349,306,

granted May 23, 1944.

Devices of the type indicated are commonly employed for the control of gas-buming systems, the device usually being so arranged as to be heated by the flame of a pilot burner provided for the ignition of the main burner of the system, so that the device serves not only as a convenient source oi electrical energy independent of the utility service, but also as safety means which, due to the resultant cessation of generation, acts to render the system inoperative upon accidental extinguishment of the pilot burner flame.

When the device is heated by a gas flame, the dissimilar metals of which its elements are composed are subject not only to oxidation but also to the corrosive action of theburnt or unburnt gases. It has been proposed in the prior art to provide a shield or cap of stainless steel for each of the hot junctions of the device to protect them from the direct action of the flame; however, such means have been found to be inadequate, particularly whenhigh direct and/or ambient temperatures are involved, because of the penetration of the gases beneath the shield. It is therefore an object of my invention to provide means for hermetically sealing the heated portions of the thermocouple elements from the atmosphere and other gases, without materially reducing transfer of heat to the hot junctions.

Another object is to provide a thermoelectric generating device comprising a metallic container for a thermopile, which container provides means for maintaining the hot-junction portions of the thermopile in good heat-transfer relation to a portion of the container adapted to be subjected to a source of heat.

Other objects and advantages of the invention will be. found in the description, the drawing, and the claims; and, for full understanding of the invention, reference may be had to the following detailed description and accompanying drawing, wherein:

Figure 1 is a longitudinal sectional view of a thermoelectric generating device embodying the invention; and

Figure 2 is an enlarged transverse section taken along the line 22 of Fig. 1.

In the drawing, the numeral I l indicates a cylindrical tubular member, or housing, of relatively thin sheet metal. The upper end'of this member is closed and provided in its end wall with a deep central depression I! which forms with the side wall of the member an internal annular recess l3 (Fig. 2) for reception of the twisted hot-junction end portions of a thermopile. This thermopile comprises agenerally circumferentially-arranged group of pairs (six pairs, as shown) of thermocouple elements or wires i5 joined together in electrical series.

As is seen in Fig. 2, the individual wires of the thermopile are threaded through a circular row of holes It in a disk ll, of ceramic material such as porcelain, and are twisted together at opposite sides of the disk to form the upper hot-junction portions [4 and cold-junction portions l8; the junctions themselves being at the points of first contact of the elements, as indicated at M and I8 for the respective hot and cold junctions. It will be understood that the terms hot and "cold are herein employed merely as a convenient way of indicating the opposite junctions of a thermocouple; the hot junction being the one which is to be subjected to heat or cold, while the cold junction is the one subjected to ambient temperature. The materials of the thermocouple elements may be selected from any of the wellknown metals or alloys having highly different ChromeP and Copel.

thermoelectric powers, such as, for example,

To avoid possible confusion, the back pairs of elements are not shown in Fig. 1, nor are the end elements of the thermopile whereby it is connected in an electrical circult; it being believed that the arrangement of the thermopile will be apparent to those skilled in the art. The general structure or the present device is the same as that disclosed in my Patent No. 2,349,306 referred to above.

The active portions of the thermocouple elements between their hot and cold junctions (i. e., between the points of first contact ofthe elements at opposite sides of disk l'|-) are preferably quite short, as shown, so that the electrical resistance of the thermopile will not be excessive when it isconstructed of materials having high resistivity, such as the alloys mentioned. In order to maintain the cold junctions relatively cool despite their proximity to the hot junctions, each of the coldjunctio'n portions i8 is attached to a tube IQ, of metal, such as copper, having high thermal conductivity, which extends through openings in insulating disks.20 and 21 to the lower end of the tubular member II where the temperature is always relatively low since only the extreme upper end portion or tip of the tubular member is intended to be subjected to the flame or other source of heat. This heat-dissipating feature is covered in the copending application of William R. Ray,

Serial No. 265,974, filed April 4, 1939; now Patent No. 2,374,701, granted May 1, 1945.

Sealingly closing the bottom end oi. the tubular member II is a base fitting 22 wherein are provided contact elements or prongs 23 adapted to cooperate with an electrical socket (not shown) of the .type employed for mounting conventional vacuum tubes. Sealing of the contact elements in the base fitting 22 may be accomplished in any convenient manner: for example, if the base is of molded insulating material, the material can be molded around the contact prongs; or it it is of metal, the prongs or the leads can be mounted in glass beads as in metal radio tubes. The innet ends of the prongs 23 are connected to copper tubes 24 which in turn are connected to the end elements (mentioned above) of the thermopile. A rod 25 maintains the disks ll, 20 and 2| in relation to each other and to the tubular memher, and thereby holds the hot-junction portions M of the thermopile within the recess l3. Thin wrappings 26 (shown of exaggerated thickness in the drawing) of mica or other suitable material are employed .to electrically insulate the hotjunction portions from the tubular member, the

recess 13 having a width such as to tightly receive the insulated hot-junction portions. The rod 25 extends from the base 22 through central openings in the disks ll, 20 and 2| and is pinchedout at their opposite sides to provide the required support.

The interior of the device may be evacuated, or, preferably, filled with an inert gas, such as nitrogen, to aid conduction of heat away from the cold-junction portions l8 and their extensions IS.

The embodiment of my invention herein shown and described is obviously susceptible of modiflcatlon without departing from the spirit of the invention, and I intend therefore to be limited only by the scope of the appended claims.

I claim as my invention: v

1. A thermoelectric generating device adapted to be subjected to a source of heat and comprising, in combination: an elongated tubular member closed at one end and formed of relatively thin sheet metal, a thermopile within said tubular member and comprising a plurality of pairs of elongated thermocouple elements arranged in substantially parallel axial relation to each other and to the member and forming at their opposite ends a plurality of hot and of cold junctions, said closed end of the tubular member being centrally depressed to form internally an annular recess for so closely receiving the hot-junction portions of said thermocouple elements that they are maintained in good heat-transfer relation to said end of the member, and means for electrically insulating said hot-junction portions from the member.

2. A thermoelectric generating device adapted tube subjected to a source of heat and comprising, in combination: an elongated tubular member closed at one end and formed of relatively thin sheet metal, a thermopile within said tubular member and comprising a plurality of pairs of elongated thermocouple elements arranged in substantially parallel axial relation to each other and to the member and forming at their opposite ends a plurality of hot and of cold junctions, said one end of the tubular member being centrally depressed to form internally an annular recess for so closely receiving the hot-junction portions of said thermocouple elements that they are maintained in good heat-transfer relation to said one end of the member, means for electrically insulating said hot-junction portions from the member, and a base-fitting closing the opposite end of the tubular member and having contact elements for connecting the thermopile in an external electrical circuit.

3. A thermoelectric generating device adapted to be subjected to a source of heat and comprising, in combination: an elongated tubular. member closed at one end and formed of relatively thin sheetmetal, a thermopile within said tubular member and comprising a plurality of pairs of elongated thermocouple elements arranged in substantially parallel axial relation to each other and to the memberand forming at their opposite ends a plurality of hot'and of cold junctions, heat-conducting means joined to and extending from each of said hot junctions generally axially of the elements, said one end of the member being centrally depressed to form internally a deep annular recess for so closely receiving said heat-conducting means that they are maintained in good heat-transfer relation to said one end of the member, and means for electrically insulating said heat-conducting means from the member.

4. A thermoelectric generating device, as defined in claim 3, including a base-fitting for closing the opposite end of the tubular member and.

having contact elements for connecting the thermopile in an external electrical circuit.

WILLIAM A. RAY.

REFERENCES CITED The following references are of record in the file of this. patent:

UNITED STATES PATENTS OTHER REFERENCES Patton et al., Ind. and Eng. Chem., anal, ed.,

vol. 13, 1941, pages 823, 824. (Copy in Div. 59.)