US733610A - Rheostat. - Google Patents

Description

NO MODEL.

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William UNITED STATES i rtented .fury 14, 190s. PATENT OFFICE.

WILLIAM C. YATES, OF SCHENECTADY, NEW YORI{,'ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

RHEOFSTAT.'

srEcIFrcATIoN forming part' ef Letters :Patent No. 733,610, elated` .my 14, 190e'. Application led October 3,1902. Serial No. 125,799. (No model.)

To all whom t may concern:

Be it known that I, WILLIAu C. YATEs,a citizen of the United-States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Rheostats, of which the followingis a specification.

This invention relates to a device for regulating the flow of current in any electric cir- Io cuit in which it may be introduced by gradually cutting in and out a resistance-coil which consists of numerous turns of wire partially embedded in insulating material, but exposed along the path of a switch-arm. By having the switch-arm move directly over the coils of the resistance-wire I do away with contactblocks connected to the wire at intervals, and this enables me to increase or diminish the resist-ance by very small steps. In fact, Inovezo ment of the switch-arm can be made so slight that only one turn of the coil is cut into or out of the circuit, thereby increasing or diminishing the resistance of the circuitI by only the resistance in one convolution of the wire. On

the other hand, the switch can be moved over the whole length of the coil, and thus connect into the circuit the entire length of the resistance-wire. In this way I obtain an effective rheostat, simple and economical in construc- 3o tion.

In carrying out my invention I provide an electrical conductor in the form of a coil and lay it in a groove in a block of slate or other lireproof insulator, so that a side of the coil extends slightly above the face of the insulating-block. Then I fill the grooves and'thus partially embed the coil by pouring in such insulation as cement or any other insulating material which can be introduced in a fluid 4o or plastic condition and which will harden and become solid either naturally or by the application of heat. I prefer to use Portland cement, or a mixture containing the same, for this purpose, not only because it can be used 4 5 in a plastic state and afterward hardened,

but also because it is capable of withstanding a considerable degree of heat; but I do not limit myself to any particular material, it being necessary only that the material used 5o should be an insulator and be capable of being molded into form around the resistancecoil. Thus the embedding substance insulates the portion of each turn ofthe resistancewire below its surface from the next-turn and `holds the exposed portions rigidly and a suiii- 5 5 cient distance apart to prevent accidental Vcross connection, and, further, it absorbs much of the heat from the surface of the electrical conductor, thereby enabling it to carry a much greater current than it would be ca- 6c pable of Were itnot so embedded. I prefer to undercut the sides of the groove in the insulating-block,so as to make the cement more secure in the groove. A switch-arm is mounted to move over the exposed portion of the coil and make electrical contact therewith.

In'order to increase the range of the rheostat, I Iind it convenient to provide two parallel or concentric coils of wire, each embedded in insulating material, and aswitch carrying a 7o bridging contact making contact with the eX- posed portions of the two coils. Thus any movement of the switch increases or diminishes the length of that portion of each of the two coils that is connected in the circuit, thereby giving the rheostat double the range it would have if only one coil were used. In this form of my device I make the two arms of the switch separate, so that an irregularity in one coil raising the switch-arm bearing on 8o that coil would not raise the other switch-arm oif the other coil.

In the accompanying drawings I have shown an embodiment of my invention having two coils and a two-armed switch making contact therewith.

Figure l is a top plan view; Fig. 2, a side elevation 3 and Fig. 3, a cross-section along the line :I: or., showing the partially-embedded coils. 9o

A is a base-block, preferably of slate or other insulating and heat absorbing substance, having two circular concentric grooves B B cut in its upper surface. These grooves are preferably undercut, as indicated. On the under side of the base are mounted terminals M and N, extending through the plate to corresponding points in the grooves B B, respectively. In each of these grooves is placed lengthwise a continuous helical coil Ioo of wire C C of predetermined resistance, one side of each coil extending slightly above the surface of the `block A. The coils C C' are connected at one end to the upper ends of the terminals M and N, respectively, and from these terminals they extend almost around the grooves B B, being connected at their extremities to the upper ends of metallic studs M N, respectively. These studs are mounted on the under side of the block A and extend through the grooves B B. They are connected on the under side of the base by the wire h, so that the circuit will not be broken if one of the switch-arms is raised oit' the coil. The grooves 'B B are iilled with a suitable insulating-cement or other insulating heat-absorbing material, so that the coils C G are embedded in insulation except for the side which extends above the face of the base A.

D D are spring switch-arms adapted to bear down on the exposed sides of the coils C C. They are mounted one directly over the other and electrically connected at the handle E, which is pivoted at the center of the circular grooves. Contact between the coils might be made by a simple bridging-brush mounted on the end of an arm lixed to the handle; but I prefer the construction shown, since it admits of independent pressure on each helix, and thus prevents poor contact if the wear should be uneven or if one or more turns in either helix should be bent or otherwise damaged.

F is a stud set in the base A between the spaces between the ends of the coils and the pivot of the handle to prevent the switcharm from passing from one end of the coils to the other without moving over their entire length.

The rheostat is connected in the circuit at M and N. In the position shown in Fig. l the current enters at M and goes to the coil C, along the switch D, back over the switcharm D and the coil C to the contact N. In this position the resistance is nil. As the switch is moved over the coils it cuts into the circuit successive convolutions of the coils over which it passes, vfor then the current has to pass along the coil C from M to the arm D and along the coil C from arm D to N. IVhen the switch-arms have been turned completely around to the extreme position resting against the stud F, the entire length of each coil is in the circuit, and the current passes from one coil to the other through the switch-arms or over the wire 7L.

IVhat I claim as new, and desire to secure by Letters Patent of the United States, is-

l. A rheostat having a coil or coils of`wire embedded lengthwise in insulation so that the convolutions are exposed along one side ol the coil or coils, and a switch-arm makin g contact with the exposed portion.

2. A helical coil of wire, the convolutions of which are surrounded with insulating material, except on an exposed side and a switcharm adapted to move over and make contact with the exposed portions of said convolutions.

3. In a rheostat,in combination with a base, a coil or coils of wire sunk lengthwise in insulation so that a portion of each convolution extends above the insulation and is exposed, and a switch adapted to move over and make contact with the exposed part of said coil or coils.

4. A rheostat having resistance-wire coiled in the form of a helix and sunk in an insulating substance so as to leave one side of the coil exposed, and a switch-arm adapted to move over and make -contact with said exposed portion.

5. A rheostat having two resistance-wires coiled and embedded lengthwise in insulating material so that a portion of the coils extends above the insulating material and is exposed, and a two-armed switch adapted to move over and make contact with the exposed portion of said coils.

i5. A rheostat having two resistance-wires coiled and embedded lengthwise in insulating` material so that a portion of the coils extends above the insulating material and is exposed, and a bridging device adapted to move over and make contact with the exposed portion of said coils.

7. In a rheostat, two wire helices laid in concentric grooves and partially embedded in linsulating material, and means for making contact with the exposed portion of said helices.

S. A plurality of wire helices supported in insulating material and surrounded thereby except along an exposed side of each helix, and contact-bril shes making contact with said exposed sides to vary the resistance in circuit.

A plurality of wire helices supported in insulating material and surrounded thereby except along an exposed side of each helix, and a contact device making contact with said exposed sides to vary the resistance in circuit.

10. In a rheostat, two wire hel ices connected IfO IIO

at one end, an insulating substance inclosing said wire except along an exposed side of each helix, and a contact device making contact with the exposed sides to vary the resistance in circuit.

In witness whereof I have hereunto set my hand this 2d day of October, 1902.

IVILLIAM C. YATES. Iitnessesz BENJAMIN B. HULL, HELEN ALFonD.

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