US2470864A - Thermoelectric control device - Google Patents

Description

May 2 4, 1949. w. A. RAY

I THERMOELECTRIC CONTROL DEVICE Filed Sept. 18, 1946 3nventor: WILLIAM A. QAY.

attorney;

Patented May 24, 1949 i 'UNlTED STATES PATENT OFFICE THERMOELECTRIC CONTROL DEVICE William A. Ray, North Hollywood, Calif., assignor to General Controls (30., Glendale, Califi, a corporation of California Application September 18, 1946, Serial No. 697,817 4 Claims. (01. 1759-320) My present invention relates to means for controlling the energization of an electric circuit in accordance with temperature changes, and more particularly to such means wherein the thermostatic element is relatively. remote from the switching device, as in a system employing a thermocouple and relay, or thermal bulb and pressure-operated switch. Heretofore it has been necessary in such a system to mount the thermocouple or thermal bulb in its designed location, as in a boiler or adjacent a flame in a furnace, and to extend a cable or capillary tube to the relay. or pressure-switch which is separately mounted in another location; another cable being extended thence to the device to be operated, such as an electric motor or valve. It is an object of this invention to provide,,in lieu of the aforementioned arrangements, a unitary control device which is supportable solely by its thermostatic element and includes a switching device and a cable for connection to the electric valve or-other device to be operated.

For full understanding of the invention, and further appreciation of its features and advantages, reference is to be had to the following detailed description and accompanying drawing, and to the appended claims.

In the drawing:

Figure l is a 'view, with cover l3 cut away, of a control device embodying the invention;

Figures 2 and 3 are sections taken along the lines 2-2 and 33, respectively, of Fig. 1; and

Figure 4 is a view, in perspective, of a detail of the structure shown in the other figures.

In the drawing, the numeral ll generally indicates an enclosed housing consisting of a cupshaped base section [2 and a similar cover section I3 closely fitting the reduced mouth-portion of the base. Within the housing I I is an electromagnetic switching-device or relay which is mounted by means 'of a bracket l4 (shown per se in Fig. 4) on a circular base-plate l5 of insulating material; the bracket being secured to the base-plate by screws I6 threaded in holes through the bracket-portion i! (Fig. 4). The base-plate i5 is held in position against the bottom wall of the housing l by a pair of springs l8 which encircle posts I9 (riveted to the housing bottom-' wall) and are compressed against the base-plate by caps threaded on the posts and fitting in openings through the cover l3; these posts and caps also serving to hold the two sections of the housing together. Inserted below the base-plate I5 is a strip 2| of thin insulating material which ensures against electricalcontact of the screws IS with the housing.

Secured to another portion 22 (Fig. 4) of the bracket I4 is the flattened side-arm 23 of a U- shaped electromagnet core 24. The other sidearm 25 of the core is round and has a polarenlargement 26 conforming in shape to that of the opening 21' (Fig. 4) in bracket-portion 21; an energizing coil 28 encircling the side-arm 25. Fulcrumed on the enlarged beveled extremity 29 of the side-arm 23 is a blade-like armature 30 which is attractable toward the polar-enlargement 26 when the coil 28 is energized, and is biased in an opposite direction by a spring 3| compressed between the armature and a finger 32 (see Fig. 4) bent-up from the bracket [4; longitudinal and transverse movement of the armature being prevented by a thin metallic strip (clamped between the coreside-arm 23 and the bracket-portion 22) having bifurcated ends 33 (Fig. 2) fitting freely in notches formed in opposite edges of the armature. The contact-carrying end of th armature, beyond theelectromagnet, cooperates with contact screws in thebentup ends of a pair of metal strips 34 and 35 insulatingly mounted on a bent extension 36 (see Fig. 4) of the bracket-portion 22; these contact-strips having lugs '31 to which are soldered two of the wires of a three-wire armored cable 38 which extends through an opening in the housing basesection I2; the third wire of the cable being connected to the bracket-portion 22.

Extending from the side of housing II, opposite the cable38, is a thermoelectric generating device or thermocouple 40 comprising a relatively-rigid metallic tube 4| which is secured, as by solder, in an opening through the base-section 12. In the flared outer end of the tube 4|, and welded thereto, is a short tube 42 which is reduced in diameter at its outer end to fit a rod or wire 43; the extremities of th wire and tube being fused together at 44. The wire 43 runs the full length (which is conveniently about ten inches) of the tube 4| (insulated therefrom by a sleeve 45) and terminates within the housing where it is soldered to one lead 46 of the electromagnet coil 28; the other lead of the coil being electrically connected to the housing and tube 4! through a lug 41 on one of the posts l9 below spring I8. The tube 42 may be of the well-known thermoelectric alloy Chromel or, preferably, of a steel alloy having a high chromium content which better withstands high temperatures and oxidation; the wire 43 conveniently being of the alloy Copel which is thermoelectrically highly difierent from Chromel" or high-chrome steel. The approximate compositions of the alloys mentioned above are as follows: Chromel, Ni and Cr 10%; high-chrome steel, Fe 73% and Cr 27%; Copel, Cu 55% and Ni 45%. The tube 4| is preferably of copper, which is thermoelectrically similar to the materials designated for tube 42, and has low electrical resistance,

The whole control device shown (to double scale of physical embodiment) in Fig. 1 is adapted to be supported by its thermostatic element 40; as, for example, on a bracket 48 which, it is to be assumed, is attached to the main gasburner of a furnace; a pilot-burner 49, providing a flame 50 for igniting the main burner, also being supported by the bracket. Another flame 5| of the pilot-burner is arranged to heat the hot junction 52 (between the tube 42 and wire 43) of the thermocouple. When this junction is heated, current is generated by the thermocouple in an amount suflicient to cause the electromagnet to attract the armature 30 and hold it in engagement with the contact strip 36; the closed circuit of cable 38 then being through this strip and the armature (by way of bracket-portion 22 and core-arm 23). If the pilot-burner flame is extinguished, the armature drops-back into engagement with contact strip 35, as shown, breaking the aforementioned circuit and closing another circuit through the cable.

From the foregoing description it is apparent that the thermostatic device of this invention is adapted to control, in accordance with its thermal condition, energization of any suitable electrical apparatus connected to the cable 38; and because of its unitary mounting and lack of disconnected parts, its installation is greatly simplified. The specific device herein shown and described may obviously be modified 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:

1. A unitary thermostatic device for controlling an electric circuit and adapted to be mounted on a burner in thermally-responsive relation to the flame thereof, comprising: an enclosed housing; thermostatic means comprising an elongated tubular member of rigid construction extending from and rigidly secured to said housing, the outer end of said tubular member being adapted to be subjected to said flame; switching means within the housing; means within the housing operated by said thermostatic means for actuating said switching means: a cable, permanently connected to said switching means, extending from said housing so as to form, in part, an electric circuit controllable by the device; and means for supporting the device on said burner, said supporting means consisting entirely of a bracket attached to said tubular member adjacent its outer end.

2. A thermostatic device as defined in claim 1, and wherein said cable extends from said housing at a point opposite said tubular member.

3. A unitary thermostatic device for controlling an electric circuit and adapted to be mounted on a burner in thermally-responsive relation to the flame thereof, comprising: an enclosed housing; a thermoelectric generating device ex-z tending from said housing and comprising an! elongated tubular member of rigid construction rigidly secured to the housing and forming at its outer extremity the hot-junction of the generating device; switching means within the housing; an electrical relay, for actuating said switching means, within said housing and connected to said generating device for operation by the energy produced thereby when said hotjunction is heated by said flame; a cable, permanently connected to said switching means, extending from said housing so as to form, in part, an electrical circuit controllable by the thermostatic device; and means for supporting the thermostatic device on said burner, said supporting means consisting entirely of a bracket attached to said tubular member adjacent its outer end.

4. A thermostatic device as defined in claim 3, and wherein said cable extends from said housing at a point opposite said tubular member.

WILLIAM A. RAY.

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

UNITED STATES PATENTS Number Name Date 2,132,057 Thornbery Oct. 4, 1938 2,165,555 Kronmiller July 11, 1939 2,183,827 Thornbery- Dec. 19, 1939

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