US1945628A - Electrically heated device - Google Patents

Description

Feb. 6, c N ENT ELECTRI SALLY HEATED DEVICE Filed July 23, 1929 llllliill!!! IIIIIIYIH INVENI'OR CARL M CLEMENT Patented Feb. 6, 1934 PATENT OFFICE 1,945,628 ELECTRICALLY HEATED DEVICE 4 Claims.

This invention relates to electrically heated devices, and more partiisularly to a novel means for thermostatically controlling such devices.

Electrically heated devies, including utensils for domestic use and commercial equipment, have commonly been controlled by the mechanical expansion or distortion of thermo-electric couples or similar elements, depending in their action upon the heat generated in the device itself. The controlling device is thus subjected to extremely exacting conditions and cannot be depended upon for long life or for accurate controlling action after being used for any considerable length of time. It is with this general problem that my invention is concerned and its object is to improve the accuracy of thermostatic control, increase the lite and liability of action of the controlling means, and simplify the construction of the electrically heated device as a whole.

To this end I propose to employ a thermo-electric generator of the thermopile type for controlling the heating circuit of electrically heated devices. I have discovered that a thermopile, working in a range of relatively slight temperature difference may be satisfactorily employed to operate a switch for'controlling the resistance of a heating circuit. Consequently, I am enabled to locate the thermopile outside the body of the electrically heated device, where it is subjected to relatively slight temperature differences, which may be controlled by connecting the thermopile to the electrically heated device by heatconductive members of the proper dimensions. In'one aspect, therefore, my invention consists in an electrically-heated device having a heating circuit of adjustable resistance, a thermopile associated with the device and arranged to beheated thereby, and an electrically operated switch in circuit with the thermopile and acting to control the adjustable resistance of the heating circuit.

An important field of use of my invention is in irons for domestic use and in this embodiment of the invention the thermopile may be-convenient- 1y located in the handle of the iron, where it is removed from the direct and intense heat of the bodyof the iron. Preferably the supports for the handle will be used as heat-conductive members. for transmitting to the thermopile an amount of heat adequate to insure its effective operation.

These and other features of the invention will be best understood and appreciated from the following description of a preferred embodiment Carl v. Clement, Beverly, Mass. Application July 23, 1929. Serial No. 380,317

Fig. 1 is a view in horizontal section on the line 1-1 of Fig. 2;

Fig. 2 is a view in vertical section;

Fig. 3 is a view in cross section of the handle on the line 33 of Fig. 2; and

Fig. 4 is a diagrammatic view of the thermopile and the electric circuits of the device.

I have illustrated my invention as embodied in an iron having a solid base portion G, above which is formed an enclosed chamber by a sheet metal shell T held firmly to the baseby four vertical bolts J. A heating coil of resistance wire Q extends about themargin of the base G and is connected at one end to a lead-in terminal P. The upper portion of the shell 'I is thickened to form a supporting plate, to the under side of which is secured an auxiliary resistance coil R connected at its rear end to the resistance coil Q and at its forward end to the second lead-in terminal P. Beneath the auxiliary resistance coil R is secured a leaf spring U, constituting one element of a switch, as will presently-be explained, andacting normally to short circuit the auxiliary resistance coil R by contact with it throughout its'length. The spring or switch member U is secured to the shell by a screw Y, which also assists in holding in place a strip of insulating material which is interposed between the auxiliary coil R and the thickened part of the shell-T.

Secured to the base G of the iron is an electromagnet N, comprising two horizontally disposed coils and an armature M pivotally secured to the core of one coil and having a curved slot for the reception of the core of the other coil, whfi feby it may be swung up or down about its righthand end, as seen in Fig. 2, for purposes of adjustment. The upper portion of the armature lies beneath the free end of the switch member U and in position to deflect this member downwardly and away from the auxiliary resistance coil B. when the electro-magnet N is energized. The position of the-armature M is adjustably controlled by a vertical adjusting screw W which extends freely through the shell T at its upper end, where it is provided with a head by which it may be conveniently turned. At its lower end it threaded into the armature and when turned in a clock wise direction will lift the free end thereof, bringing it closer to the under side of the switch member U so that the latter will be more delicately responsive to the energizing of the electro-magnet N. y

The handle of the iron is connected to the body portion by a metallic strip V bent upwardly at both ends and thus forming two spaced heatw, I ,illoM ,1.

the rods ternately at their handle, as shown in l. bly is contained withinan insulating shell in serted in the handle of the iron. The thermopile is electrically insulated at each end by disks D of suitable material which are engaged by a pair of metallic disks E connected to or formed as a part of the heat-conductive members V.

The thermopile is disposed in circuit with the electro-magnet N in the body of the iron, being connected thereto by insulated wires K and L which pass down the rear heat-conductive member through the shell T and to the-electro-magnet N.

In Fig. 4 I have diagrammatically illustrated the two circuits using the same reference characters as are applied to the device itself.

Referring particularly to Fig. 4, it will be seen that one lead-in terminal P is connected to the principal resistance coil Q and that the circuit extends from the outer end of the coil Q to one end of the auxiliary resistance coil R, and from the other end of the resistance coil it back to the second lead tin terminal. The flexible switch member U is shown as short-circuiting the auxiliary heating coil R. The thermopile 4A B is shown as in circuit with the electromiagnet N, and M represents the armature of the magnet which is lo cated in proximity to theswitch member U.

In operation, the iron is connected to a power circuit at the lead-in terminals 1? and the body of the iron is gradually heated by the heat generated in the principal resistance coil Q. As the hotly of the iron increases in temperature, heat is conducted upwardly through the spaced heat-conductive branches or the member V and the disks E at the outer ends or the thermopile are warmed. This continues until the temperature difference between the ends 01' the thermopile and the center thereof, where the thermo-electric rods are joined, is suflicient to generate a current in the thermopile circuit, thus energizing the electromagnet, N and moving the switch member U downwardly into contact with the armature M and out 0! contact with the auxiliary resistance coil R. When this occurs, the additional resistance of the auxiliary coil R is cut into the main heating circuit. The current is correspondingly cut down and the device as aJWhofle is reduced in temperature. The switch member U, however, is held down as long as current is being generated in the thermopile and heating of the irony con and the e its ini As a tie governing e resistcircuit as above tplained,

temperature or the body of the iron may be .cintained uniform within a few degrees of temperatnre.

"While I have disclosed my invention as embodied in a sad iron, it will be understood that it may be embodied with equal advantage in an electrically heated soldering iron, curling iron, or any other electrically heated utensil for domestic purposes, or in an electrically heated wax pot, shuttle case, or electrically heated commercial equipment of any other type.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. An electrically heated device having a heating circuit of adjustable resistance, a thermcpile mounted outside said device, heat conductive members extending between said device and thermopile, and an electrically controlled switch associated with the thermopile and acting to govern said adjustable resistance.

2. an electrically heated device comprising an operative member having a heating circuit of adjustable resistance for heating the same, an electro-magnet, a switch associated therewith for controlling the heating circuit, a pair of spaced heat conductive members projecting from said operative member, and a thermopile mounted between the outer ends of said heat-conductive members and disposed in circuit with said elecho-magnet.

3. An electrically heated device comprising an operative member having a heating circuit of adjustable resistance for heating the same, an electro magnet having an adjustable armature, a resistance-controlling switch arranged to be 011-- erated by said electro-magnet and governed in its action by the setting of the armature, a heatvconductive member connected to said operative member, and a thermopile carried thereby and disposed in circuit with said electrc-magnet.

4. An electrically heated, thermostaticallycontrolled iron having a heating circuit of adjustable resistance in its body portion and also an electro-magnetically operated switch for governing said heating circuit, and a thermopile located in the handle of the iron, having thermal connection to the hotly thereof and being disposed in circuit with said e1ectro-magnetically operated switch.

CARL Claim/TENT.

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