US539216A - Rheostat - Google Patents

Description

(No Model.)

A. C. CAREY.

Patented May 14, 1895.

UNITED STATES PATENT OFFICE.

AUGUSTUS U. CAREY, OF LAKE PLEASANT, MASSACHUSETTS.

RH EO STAT.

SPECIFICATION fOImIlg part Of Letters Patent N0. 539,216, dated May 14, 1895.

Application filed February 26, 1895. Serial No. 539,779- (No model.)

To all whom it may concern.:

Be it known that I, AUGUSTUS C. CAREY, a citizen of the United States, residing at Lake Pleasant, in the county of Franklin and State of Massachusetts, have invented a certain new and useful Improvement in Rheostats, of which the following is a full, clear, and exact description.

This invention relates more especially to the construction of the wire-holding spool, and the laying on of the wire and insulating and protecting it. The spool has a body of metal and an insulatingr barrel and heads of mica, or other refractory and insulating material, and the wire is wound thereon in layers, which layers and the various turns of wire thereof areinsulated from each other. The invention comprises these main and other minor features of construction, as hereinafter described and claimed.

In the accompanying drawings, illustrating this invention, in the several gures of which like parts are similarly designated, Figure l is a side elevation; Fig. 2,v a vertical section. Fig. 5 is a diagram illustrating the Winding of the spool. Fig. iis a cross-section on line 4t A, Fig. l, showing the under side of the top head of the rheostat. Fig. 5 is a cross-section on line 5 5, Fig. l, showing the upper side of the lower head; and Fig. 6 is a cross-section on line 6 6, Fig. l.

The lower head ais made with a hub or boss a', the interior of which is made tapering so as to be frictionally fitted to an electrolier or other fixture without the necessity of turning the rheostat, thus avoiding the danger of twisting the conductors. A set screw a2 may be used to fix the rheostat in position. A central tube o is secured in the boss a by a set screw b. The top head c is made with aboss c', which is fitted to the tube b, as by a setscrew c2. The tube b extends beyond the boss c sufficiently far to admit of the lamp or other object being securely fitted thereto in any suitable manner.

d is the return or leading-out conductor. The leading-in conductor e, e is divided so as to include the rheostat, the part c extending from the distributing plant to the rheostat and the part e extending from the rheostat to the lamp or other obil ect to be supplied.

These conductors are arranged within the tube h.

The adjacent faces of the heads a and c are supplied with one or more layers (dat rings) of mica, f, g, or other appropriate refractory and insulating material, which may be riveted or otherwise secured thereto.

The head a has secured to its mica lining the contact spring h, which I prefer to provide with a roller contact h', and this spring is connected by wire h2 with the leading-in Wire c, said wire h2 extending through a hole b2 into the tube b. The head c is provided with a contact plate i applied to the mica lining, and having its ends t" turned down to form stops. This contact plate is connected by wire 2 passed through a slot b3 in the tube b, with the leading-out section e of the divided leadingin wire e, e'.

The spool containing the rheostat or resistance wire is composed of a metallic barrel 7c and heads 7c', k2, arranged to be revolved about the tube l), a knob or handle l being applied to the head 7c for this purpose. The spool may be supported so as to be thus freely revolved, upon a coiled spring m, interposed between it and the lower head aand encircling the tube b.

The barrel of the spool is provided with a tube or jacket a, of mica or other refractory and insulating material, and the adjacent faces of the metallic heads, 7c', le?, are provided with a series, three, more or less, of mica rings o, which may be secured to such heads in any suitable manner. I prefer to use a series of three rings and securely rivet the spool next adjacent to the metallic heads to such heads, leaving the internal ring free. A series of contact pieces p, p,p2,p3, more or less, are secured to an intermediate one of the mica rings o in any suitable manner, and a contact piece q is secured similarly to the mica rings of the upper head of the spool, and the contact pieces p3 and q are connected by a connecting strip or Enger rr, which is secured to each and extends thence above the spool and into wiping contact with the contact platee' of the upper head of the rheostat, the projections t', t', of such contact plate fr' forming stops to limit the movement of the spool by arresting the movement of the finger.

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The spool is wound with wire, s, in insulated layers, and I prefer to wind the spool in the following manner, referring more especially now to diagram Fig. 3: I prefer to use silkcovered German silver wire, and the naked portion thereof is first `secured to the contact piece p, and is ythen wound about the spool from one end to the other and coated with a coating of liquid cementitious matter of 're= fractory and insulating nature, s. I have found an efficient mixture for this purpose to consist of water-glass and. finely powdered chalk of proper consistence to spread easily. This cementis thoroughly applied tothe layer of wire so as to cover it externally and to enter in between its turns; and after so coating the layer, the winding is continued to the starting point, and another layer of cement applied, and then another layer of wire and another layer of cement, and finally, thefourth layer of wire and fourth `layerof cement yandk the wire is then stripped'of its silk covering for a short distance and the ynaked port-ion wound once or more Varound the contact p", the-naked wire having been passed to the'far side of said contact to begin the winding, and

then a second winding of four layers of wire with interposed cement `is placed Iupon the spool and the silk covering again stripped from the wire andthcwire woundabo'ut contact p2, and another turn of vfour layers'of Wirev applied to the spool alternating with l'ayers of cement, and theendof the wire is then finally stripped and wound around vthe contact p3 in such manner as to be in intimate union with the nger'or stript". 1 Care should be taken that the cement be thoroughly-dried, otherwise there is danger of short circuitin'g.

In Fig. 2, for clearness in thedrawingsfl have shown three layersof wire, but it is to be understood that ea'chvof these layers repre'- sents in point of fact four turns of th'ewire, asjust described,and the saineis true of Fig. 6.

The operation is obvious, but it, may `be stated that if kthe contact roller'hbe lbrought into contact with the contact p, the current will pass through the four layers of wire first wound on to the'spool and go thence to contact p', and then through-the ksecond four layers of wire to contact p2, and then through the final four layers of wirelto contact p3, and thence through the strip or iingerr to con-tact plate t', and so on to the lamp, thus putting in the full measure of resistance. l Any less measure of resistance may be included in the circuit by vmovin-g the spool so as to place one or the other of contacts p' or p2, in engagement with the contact roller h. If tlie contact piece p3 be placed in engagement with the contact Iroller h,f'obvi'ously the 'current goes directly therefrom through the linger fr to the lamp; and so, also, obviously,if the spool be turned so as to move-its contactpiece p beyond the contact roller h', (tothe right, Fig. 3,) then 'the current isV shut out from the lamp or other object altogether. Thus the rheostat may be used not only for purposes of resistance, but also to turny on and ed the current fromtheobject to be supplied.

An outer casing t may be applied between the heads a and c, and said casing may be provided with openings t', t', for purposes of ventilation. Y

l. In a rheostat having heads or ends, a central tube upon which they are mounted and through which the main conductors pass, refractory and insulating linings for the adjacent Vfaces of said heads, contact devices ap' plied to such linings and connected with the leading-in conductor, and a rotary spool provided with a series of layers of wire insulated from one anothe'randfrom'the s'pooland pro* vided with contacts-for inclusionin the main circuit, substantially as4 and for the purpose described.

2. In a rheostat having heads or ends, a central'ftub'eupon which they are mounted and through which the main conductors pass, refractory and insulating linings for the adjacent faces of said heads, contact devices applied tosuch linings andconnected with the leading-in conductor, and a rotary spool arrangeduponsuch tube'between the heads and havinga jacket yof refractory and insulating material, aseries lof layers of wire insulated from one another,and contactsfor including such layers of 'wire'lin Ithe mai-n circuit, substantially as described.

3. In a rheostat having r heads or ends7 a central tube upon which they aremounted and through which the main conductorspass, refractory and insulating linings for 'the adjacent faces of said heads, contact devices applied to 'such linings and'connectedwith the leading-tin conductoigand a rotary spool hav- 4ing a'barre'l vand heads lof metal jacketed with a refractory 'and insulating material, such as Y mica, ia series of layers of wire wound about such yjacketed spool and Ainsulated from one f another', and aseries of independent contacts for including 'any number of such layers of wire inthe main circuit, substantially'as described.

` 4. In a rheostat having heads or ends, a

y-central 'tube upon whichtheyare 'mounted and through which the lnain conductors pass, refractory andinsulating linings for the adjacentfa'ces of said heads, contact devices applied to such linings andconnected with the leading-in conductor, anda rotary spool having an vinner jacket of refractory and insulating material, a series of layers of wire arranged upon such jacketed spool andinsulated from one another andrneans to cut into and out of the main circuit any number of such layers of wire, substantially as described.

In testimony whereof I have hereunto set rny h'and vthis 23d'day of February, A. D. 1895.

AUGUSTUS C. CAREY.

' Witnesses:

HATTIE E. HAsKINs WALTER S. ROBINSON.

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