US474957A - Rheostat - Google Patents

Description

(No Model.) 2 SheetsSheet 1,

A. B. HERRICK.

RHEOSTAT. No. 474,957. Patented May 17, 1892.

(No Model.) 2 Sheets-Sheet 2 A. B. HERRIGK.

RHEOSTATE No. 474,957. Patented May 17,1892.

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' UNITED STATES PATENT OEEIQE.

ALBERT l5. HERRICK, OF BAYONNE, NEW JERSEY.

RH EOSTAT.

SPECIFICATION forming part of Letters Patent No. 474,957, dated May 17, 1892.

Application filed October 12, 1391. Serial No. 408,418. (No model.)

To all whom it may cmwcrn:

Be it known that I, ALBERT B. IIERRICK,L citizen of the United States, residing at Bayonne, in the county of Hudson and State of New Jersey, have invented a certain new and usefulImprovement in Rheostats or Regulators, of which the following is a specification.

The present invention relates to devices for regulating the resistance in electrical circuits, and especially for regulating dynamos and for cutting in or cutting out the resistance gradually by forming a large number of subdivisions of the resistance-conductor. The rheostat to be described belongs to that class in which a resistance-conductor is insulated for most of its length, but is bare along the path of a switch arm or device, so that said arm or device rubs (lirectlyon the conductor and no special contact-blocks are needed for said arm to travel over.

The objects of the invention are primarily to obtain an economical, simple, and efiicient construction for such rheostats.

In the accompanying drawings, Figure 1 is a plan view of one form of the resistance. Fig. 2 is a cross-section of Fig. 1 on line 00 00. Fig. 3 is a side view of a modified form, the side of the inclosing case being removed. Fig. 4 is a view at right angles to Fig. 3, and Figs. 5 and 6 are detail views for showing the circuit connections.

In the switch to be first described 1 is a cast-iron or other suitable fire-proof inclosing box or frame for the resistance devices. The resistance-00nductor is preferably in two sections, each section being wound on a frame, which is substantiallyrectangular and which consists of two insulating and heat-resisting or fire-proof plates 2, preferably of slate, which are held paralleland at a suitable distance apart by posts 3. These posts, instead of being made continuous, as shown at the right of Fig. 2, may be made shorter and tubular, as indicated at the left of Fig. 2, and may be extended by means of the rods at, spiral springs 5 being placed, as shown, to press the plates apart. The resistanceconduetors 6 are mounted 011 these frames. Before being wound the conductor is insulated throughout its length. The frames, with their conductors, are mounted on each side of the spindle 7 of a switch-arm 8, and the insulating material is removed from the surface of the conductors in arcs corresponding to those over which the two ends of the switch-arm move. These uninsulated portions of the conductor are indicated by the light spaces 9. One wire of the circuit in which the resistance is to be inten posed is connected to the block 10, to which an end of one of the resistance-conduetors is connected, and the other wire is connected to the block 11, to which the opposite end of the other resistance-conductor is connected.

12 13 are idle contacts, on which the switcharm rests when the circuit is open. The first movement of the switch-arm will throw the said arm onto the bared resistance-conductor at the two opposite ends, throwing the whole of both of said conductors into the circuit. As the arm is moved forward the successive turns of the two conductors are thrown out of circuit, thereby very gradually reducing the effective resistance and doing it without sparking, owing to the small difference of potential between adjoining turns of the cond uctors until when the switch reaches the limit of its movement a complete short eircuit through the rheostat is closed.

In the switch illustrated in Figs. 3 and t the frames on which the conductors are wound are of different construction, being composed of side plates 14; 15, held in proper relative position by cross-blocks 16 and having their upper edge in the form of an arc of a circle the center of which is at the pivot 18, which carries the switch-arm 19 and handle 20. A resistanceconductor G is wound on each of the two frames, constructed as described, and said conductors are bared along the upper curved surfaces or edges on which the switch-contacts 21, carried by the spring-arm 22, are moved. The two frames, with their conductors, are mounted in cast-iron or other suitable frames 23, which are secured together by rods 24: and which are provided with ledges 25, around which a wire screen 26 is secured. At one end of the contact-edge of the frames described are idle-contacts 27, on which the switch-contacts 21 rest when the switch is in its open position. Beside these contacts are contacts 28, to which ends of the resistancecondn'ctors are connected. At the opposite ends of the frames are contacts 29, to which the opposite ends of the resistance conductors are connected. The circuit of this resistance device is indicated in Fig. 5, one wire entering at 29 011 one side of the switcharm and the other wire connecting with the opposite contact 20. WVhile the switch-arm rests on the contacts 27 the circuit is open; but when it is moved forward the entire resistance is thrown into the circuit and is then gradually cut out, as already described. I may connect the resistance-conductors end to end, as indicated at 3o, Fig.6. In this case the operation of the rheostat would be slightly different, since the switch-arm would serve merely to short-circuit more or less of the resistance in an obvious manner, and this I find very useful when the rheostat is used-for example, for regulating dynamics-since the field-circuit would not be accidentally opened by a failure of the switch-arm to make connection with the resistance-00nductor, owing to accumulation of dirt or other cause, as would be the case with the circuit connections first described. Evidently this cross connection may be applied to either form of rheostat. It will be seen that the connection described can be made of very cheap material, and very little skill is required in putting the device together, and the wholedevice is practically fire-proof. The wires or resistance-conductors, being wound on the open frames, have the largest possible amount of surface exposed to the cooling influence of the air and any expansion or contraction which occurs, owing to changes in temperature of the conductors, will be compensated for by operation of the springs 5 if such springs are employed. Ordinarily, however, there will be so little expansion and contraction, owing to the shortness of each turn of wire, that it will not be necessary to guard against them.

In Fig. 2 a wedge '10 is shown between the plate 1 at the bottom and the conductor wound on the frame. Said wedge serves to tighten the conductor and also to still further admit air around it.

hat I claim is 1. The combination, in a rheostat, of two stationary insulating-frames or open structures, a resistance-conductor wound on each frame, and aswitch device the opposite ends of which are movable over the resistance-conductors, said conductors being uninsulated in the path of movement of the switch device, substantially as described.

2. The combination, in a rheostat,of a stationary body, a resistance-00nductor wound thereon, and a switch device movable in an are over the resistance-00nd nctor, said conductor being uninsulated in the path of movement of the switch-arm, whereby contact is made directly with the successive turns of the conductor, substantially as described.

3. The combination, in a rheostat, of a stationary body consisting of an insulating-frame or open structure, a resistance conductorwound thereon, whereby the outer surface and a large part of the inner surface of the conductor will be open to the air, and a switch device movable overthe resistance-conductor, said conductor being uninsulated in the path of movement of the switch-arm, whereby contact is made directly with the successive turns of the conductor,substantially as described.

4. The combination, in a rheostat, of a stationary body consisting of an insulating fireproof open structure, a resistance-00nductor wound thereon, and a switch device movable over the resistance-00nductor, said conductor being uninsulatcd in the path of movement of the switch-arm, whereby contact is made directly with the successive turns of the conductor, substantially as described.

5. The combination, in a rheostat, of a stationary fire-proof body, an insulated resistance-conductor thereon, and a switch device movable over the resistance-00ndnctor, said conductor being uninsulatcd in the path of movement of the switch-arm, the supporting body being constructed as an open frame or structure to allow air to circulate around the conductor through a large part of its length, substantially as described.

(3. The combination, in a rheostat, of a resistance in two connected sections and connected or adapted to be connected to a circuit, and a movable-switch device the opposite ends of which make contact with the two sections of resistance-00nductor, whereby as the switch is moved resistance is cut in or out, but the circuit is not opened by accidental failure of contactbetween the switch-arm and conductor, substantially as described.

This specification signed and witnessed this 1st day of October, 1891.

ALBERT B. IIERRICK.

Witnesses:

J OHN MCGLUE, E. A. STEVENSON.

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