US895822A - Rheostat. - Google Patents

Description

PATENT-D AUG. l1., i908.

WERT,

RHSTR AWLIGATION FILED JULY 12,1Qo5.

No: 39mm 3SHEETS-SHEET i PATENTED AUGK ll, 1908,

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WIRT.

RH'BOSTA' AFPLIGATIQN FILED JULY 12,1905.

'NETE @TATES PATENT CHRLES WIRT, OF PHILADELPHIA, PENNSYL'YANA, ASSIGNOR TO CHARLES WRT AND COMPANY, C-F NEWARK, NEW JERSEY, A CORPORATION OF NEW JERSEY.

RHEOSTAT.

Specification of Letters Patent.

latented Aug.' l1, 1903.

Application filed July l2, 1905. Serial No. 269,324.

To all whom it may concern:

Be it known that I, CHARLES VVIRT, a c.it izen of the United States, residing at Philadelphia, Pennsylvania, have invented a certain new and useful Improvement in Rheostats, of which the following is a description."

l the characteristics of durability with capaeity to stand a high `rate of work in proportion to size andweight, and also to Withstand a high temperature without injury. o

' ln the accompanying drawings is shown a rheostat which for the salie of clearness omits parts not needed to show the particular construction and method of maintenance, Also for the sake of clearness is shown a very heavy resistance conductor having few turns and connected to but few contact blocks. Commercial rheostats would have more steps or blocks 'in the commutator and a longer, lighter resistance conductor placed or wound into more turns Figure l shows a top View of a rheostat embodying -the invention, the shaft and.

handle broken oil, `Fig. 2 shows a side View of the same; liig. 3 shows a bottom plan View; and Fig. 4 u. iid section through the center line of the central shaft or spindle, Fig. 5 shows one conmiiitator block; a conl necting rod, and an envelop or contact clip. Fig. 6 illustrates ratherv diagraniinatically a rellexed. wire Vhaving uniform pitch7 or loop spaces. ywire in which the pitch or loop spans meas ured in the direction of the completed strip continuously decrease, thus giving the effect of increasing resistance per unit of length while retaining the advantage of using an inexpensive material of uniform section and avoiding joints. Fig. 8 shows a plane spiral and illustrates diagrainmatically the plan of arrangement of the resistance conductor when coiled into a suitable shape for a round plate (disk) rheostat. Fig. 9 is a view of a modified form of resistance. Fig. 10 is a bottom view, and Fig. l1l is a side elevation of `a modified form of envelop.

In all of the several views like parts are designated bj.' lhe same reference el. meters.

Referring io the rheestat illustrated herein the general description is as follow F ig. 7 shows asimilar reflexed.u

The rheostat consists of a resistance con ductor 1 (formed preferably of a wire reflexed or put into zig-Zag shape) wound cireularly upon itself like a roll of tape, the turns being separated electrically by two cords or strips 2, 3. With each turn there is slipped over the resistance conductor a sheet metal envelop or clip 4. so as to straddlo the resistance,l

this envelop preferably having an area as large as permissible and not too stili; to h down on both sides in close electrical contact .y

This extends with the resistance conductor. beyond the fiat face of the completed roll to serve a point of attachment for a eontact with that section of the resistance. lnstead of an envelop straddling the resistance conductor, the clip may be secured to one side, or it may straddle the conductor, but only one end may protrude beyond the'supporting body.

found with the resistance and separating the turns thereof are the two threads or strips of flexible insulating material 2, 3. These serve as an insulation; also as spacing stri s to give the desired external' dimension to t e (i 7) 1 i roll. rllie thickness of tnese strips would he predetermined, as the temperature limit of any rheostat is generally i'ixed, and to keep within such linut for a given duty a certain size will be called for as a minimum. In the construction shown, a very light weight of conductor may be used, keeping down the cost of the most expensive ite-in in the ordinary cost of the material; and having predetermined the desirable size of the structure to fill that space with the resistance material disposed in an extended manner, iilling the interspace with a material 5 having the qualities of insulation, solidity, and, so far as ossible, both heat .capacity and heat oonductivity. This material constitutes a molded supporting body. rilhere are materials of the description of artificial stone, also insulating materials in use which may be molded iii the soft state, pressed into sha e, or even poured in a semi-liquid form, whic i fuhil the requirements.

Having the resistance put into the required form with the Contact envelope located as required and extending atene side, it is only required to place these parts on a` flat surfae or into the bottom 'of a suitable temporary or permanent ease or box, place the cominutator bars 6-the sleeve 7 for spindle--the inclosing metal ring-the feet 8-S, &e., and ll in a liquid or semi-liquid insulating body to embed all these parts in a block which is later to become solid. Any suitable material for this purpose may be used, but preferably a material which does not require a very high temperature either to liqueiy or to harden.. number ol patents on plastic compositions describe a great variety of such materials, some o'l' which haye good insulating qualities. A gig or 'form may be used to locate the respective parts in correct relative position while the iilling is being applied.

Agtter the completion oi" the body of the 5`1`heostat by the soliditieation oll they insulating block the connection ot the resistance sections to the eommutator blocks may be completed by placing the wires .)-.l. As shown, these wires or rods are held at either end by being forced into slots in. the commutator and clips.

The resistance conductor is arranged in the iorm of a [lat spiral as shown in Fig. S and the connections 4 are taken at intervals progressively 'from that conductor. 'l`he result ol' this arrangement is that the conductor and the insulatingl body in which it is embedded are heated pri lessively in rings or annular Zones, instead ol by angular sectors as heretofore in disk rheostats. This re- Suits in a more unii'orm heating and a lower maximum temperature. vWhile the connections 4 are arranged in a spiral the commutator blocks (i are arranged 'in a circle, thus enabling the employment ol' a contact arm pivoted at the center olI the disli, which contact arm can be made short il` the comunitator blocks are. located within the innermost turn ol' the resistance conductor as they prelerably are.

Fig. t) illustrates a i'orm ot' resistance lstrip in which the insulating threads 2,' 3 'form the warp and the resistance wire i the Wett ol a l'abrie which is woven in the ordinary manner like. a tape or ribbon. As in the construction shown the linal supportl and insulation is allorded by a heat resisting body, it is not required that the insulating strips or threads applied to or laid withthe vresistance conductor should be lire proolI or heat resisting. l`he ellectiveness or lit'e, ol' the rheostat would not be reduced by any heat effect that could be inoduced under Commercial conditions on (lor example) cotton threads or strips ill used as shown.

Figs. 1() and 11 show a modification in which the sheet metal envelop 4 is extended to reach and overlap the end ol the commutator block. 'lhe rheostat may be wound With a resistance conductor in the l'orm olI a flat tape or ribbon. 'lhis would sacrilice the binding etl`ect ol the wire loops, which embedded in the insulating` body act to reinl'orce the strength oll the latter' in a way that a smooth Ilat strip could not.

'lhe commutator is preferably formed ol metal segments, each having a hollow' central chamber lt), and a projecting l'oot l1'. rlhe central chamber will become [illed with the molded supporting material, and will thereby become [irmly anchored in place. 'l`he projecting l'oot extends beyond the tilling (indicated by dot-ted line llig. 4) and is provided with a notch 12, within which the connector is l'orced. The parts may thereby be held iu position without the use ol` screws or solder. lhe connectors are outside oi the body, as shown, and may be adjusted or removed, as desired, without demolishing the apparatus.

llaving now described my invention what l claim :ne and desire to secure by lietters Patent is i. ln a rheostat, the combination ol a resistance conductor, contact blocks and a hub or support for the moving element, with a molded body of insulation forming the body ol the rheostat and in which the resistance conductor, contact blocks and hub or support lor the moving element are embedded and mechanically held by the setting or hardening oll the molded insulating body around them, substantially as set forth. l

2. Ina rhcostat, the combination of a resistance conductor, contact blocks and a hub or support for the moving element, with a molded body ol insulation.forming the body of the rheostat and in which the resistance. Iconductor, contact blocks and hub or support lor the. moving` element are embedded and meclumically held by the setting or hardening ol the molded insulating body around them, and a metal ring surrounding the body ot insulation and held thereon by the setting or hardening of such body, substantially as set forth. i

3. A rheostat having a spit-ally wound resistance, and a commutator inside of the resistance, both resistance and conunutator being within a molded supporting body, and radial connections between the conm'lutator and the resistance outside of the body.

4. A rheostat having a spirall wound resistanee, and a commutat'or within the spiral, both being within a molded supporting body, envelops connecting the resistance at inter'- vals within the body and projecting outside oli the body, and radial connectors between the envclops and the commutator.

5. A rheostat having a conunntatorformed otl segments mounted within a. molded su porting body, a resistance Within the body and outside ol' the conunutatm', the said coinmutator having notches in the protruding portion and radial connectors within the notches, the said connectors connecting the resistance.

t'. A rheostat having a coinniutator and a spirally wound resistance within a molded supporting body, envelops connected to the I tator and resistance outside of the body.

S. A resistance conductor` Jfor rheostats7 consisting of a rctlexed wire having its turns in the saine plane and substantially parallel with each other.

9. A spirally Wound resistance formed of a reilexed strip of varying pitch.

10. ln a rheostat, the combination of aspirally Wound resistance formed of a reilexed stri') and envelops straddling the strip at intervals. l

11. ln a rheostat, the combination of a s irally Wound resistance formed of a reexed strip mounted within a molded sugporting body, and envelops straddling t e strip at intervals Within the body, the said envelops projecting outside of the body.

12. ln a rheostat, the `combination of a spirally Wound resistance' formed of a lreilexed strip mounted Within aniolded su porting body, and envelops .straddling It .e

strips at intervals Within the body, uthe said 'envelop having notched extremities which,

project outsideof the body.

13. A resistance for a .rheostat consisting of a conductor reile'xed in the saine plane Lto form a zig-za Wire, the turns being substantially para lel with each other and coiled' ,upon itself to the shape of a llat roll or 'a disk, a body of insulation filling the interspaces Within said resistance and formln a supporting land inclosing body adapte to dissipate the heat generated in said resistance. l Y

14. A resistance for a rheostat consistin of awire or strip relexed orzig-zagged an thepiteh or linear space of the loops varying.

in regular progression in such manner as to cause a progressive change in the lengthof wire included per unit length of the efierred stri 1li. A rheosltat consisting of a continuous length of resistance wire, the turns bein substantially parallel With each other coile into (a lat roll or spiral, taps attached thereto at intervals connecting With a commutatorl and an inclosing and 'supporting body'of insulation iillingthe spaces within the vo1 urne ofv said coil and 'forming therewith a solid body adaptedto dissipate the heat produced, and to provide re uired 4mechanical su ort and electrical insu ation.

is specification signed and' witnessedi thisl30 day of June, 1905.v

CHARLES WRT;

Witnesses:

JOHN L. Lo'TsoH, SNO Roar. TAYLOR.

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