US2131590A - Snap switch - Google Patents

Description

sept. 27, r1938. C. JHATARN' 35 lots at a low cost.

Patented sept. 27, 193s 4 V Clarence John llathorn, St. Mayafla.,

to`The StackpolejCarbon'(lornpanyfst.v Marys', y Pa., a corporation of Pennsylvania` `f^ Appueanen Jnuarym, 1937,y sel-MN. 121,529

n "'*fs (0 1. zot-U67) jf My invention relates to the-control of anelec- Y Itis an object ofnmy present invention -toreduce the number of partswhich have heretofore been' used in a snap switch. l It is a further object of my inventionto Lelimi- .nate undue'sparking or the freezingof: th'e stationary terminals Aand the movable bridging member., Y Itis another object oi' vmy invention to have a'combined rolling and Irictional contact "tbetween the fixed contacts and the movable bridging memberv whereby the. main'contact surfaces will always be kept clean. YAnother object of my'invention is to provide a switch wherein the arcing occurs on auxiliary or arcing portions of the contacts, and the main contact is made. between surfacesV other than those wherearcing occurs. e f f Another objectof my invention isto reduce the size of the movable electricalbridging member so that it may be manufactured -in quantity Another object of my invention isto provide a compact snap switch of sturdy construction V which may be utilized in combination with a volume control wherein a single control actuates 40 both the switch and the volume control but .wherein actuation of the switch to closed circuit position is eiected by a relatively smallmovcment of theicontrol in one direction and 'pferxnit` ting a relatively large movement in the samedi- 45 rection without effecting the operation olfV the switch or the switch may be utilized alone.

`With the above'and related objects in view,

' my invention consists in the details of construction and the combination of parts that will hereings, in which:'-"` g Fig. 1 is a plan view of a snap switch kembodying my invention.

luefter be fully described when the description is 'read in conjunction with the accompanying draw- Fig. 31s an exploded partofthe. elements comprising my improved "snap=switch.-4

Fig; 4 is e-pianviewvof-.the msu1etedfbese 5 Fig.- 5 is a'plan Vviewol! my snap switchand its j actuator. A l. g y.; y f yIig. G'isa. lsideviewmffthe device'shown in Fig. 'l is a plan view ofafmodincationzof my l10 invention, theswitch being shown rvin anopencircuitfposition. f v I f .Fig-B is'a plan- .viewcf with a dielectric .shield positioned fbetween the; actuating spring and -thestationary terminal-- l5 Fig.;9 is a sectionalview taken. onf-the line Y.

ofFlg.'8.- v e Figlioris a pianyiewof the.dielectric'yshieldl alone. y, g :Fig-111s arfragmentary enlarged lview of the 20 vswitchfshown infFig. 7;;A f l Fig.. 12 is a vfragmentary view of l the switch partlyfin` closed circuit. position. f

in-closedf-circuit. positiomf Y f -25 Fig. :14 is -a view similarv toFigrllbutywith ,thek e l switch beingiin partial opencircuit positioniV Fig; :15 is a. .view similar 12o-Fig 11 k*but lthe switch is in partial open circuitpositionm Fig.116.is a planyiew ofthe modified electrical 30 bridging member.

Referring now in greater detail-to I 'I in Fig. 1 is vshown afmidget type of. snap `switch wherein .the overall diameter of the switchis, ape proximatelyone` inch, and thecverallthickness 'oithebase is one-quarter inch. e

'I'he switch mechanism hereinafter further described is mounted Within a cl iamberv of an insulated base;generallyfdesignated-as A, which is preferably composed of a molded vphenolic condensation product. f

A bodyportion Ill of." the baseis'tsubstantially n y at, and'iro'm the bases peripheryi whichis substantially perpendicular to 1 the Vflat surface, yextends a.- flange I2 which is-circular o'nitsfputer 45 curvedsurface. Thexflangel .I2 has 9; plurality of recesses or notcheslland I 5 on the innercurved portion. of the iiange,and, therecesses communicate with the central -chamber'of the base. The `central chamber ls'= in communication 50 with a bridging member4 and terminal chamber I6;

The'notch I4 and opening llAreceivearpintle l I 1, and the converging wallsV .18, .I9 partiallydee :lining-.the notch I4 serve as complementary stop members for a switch trigger, generallyqdesig-"B nated as B. The trigger B 'pivotally mounted Aon pintle I1 comprises a flat body portion 20,

which has openings 22,23 located atits respective ends. One opening 22 receives a portion of the pintle l1, and the other opening 23 receives a portion 24 of a torsional spring, generally designated asC. ISpacedparallel ears 25, 26 are integrallyformed fromfthe side edges of the base and extend at right angles to the base of the trigger. Each of the spaced ears 24 or 25 is engaged by an eccentrically mounted stud 21 which oscillates the trigger, hence actuating the switch. 'I'he notch I5 enablesthe coiled portion`28 of the torsional spring Cto freely fmove without engaging any portion of the flangem|2 or the,

base A.

I'he bridging member and terminalrecess I6 receives the contact portions of each of the terminals D and E, and the recess I6 also'receives an electrical bridging memben'disc, or roller, generally designatedas F. The aforementioned elements will 'be `hereinafter further described in considerable detail.

'.The torsional springChas a central coiled or closed portion 28.and from the coiled portion extend diverging legs 24 and 28. 'I'he spring C has a .tendency to expand/as well asto rapidly move the electrical bridging disc F from one-position to another position.r 4 1. 1

` Movement ofthe trigger Bdoes not actuate the bridging-disc F until the medial axis ofrtheclosed Aend of the` spring C `passes slightly beyond dead center as the trigger compresses the spring-arms of the torsional spring` C together. 1 The' energy'` stored in thespring rapidly` moves the contact,

either closing the electrical circuit 4when the terminals Dand E are bridged' or breaking the circuit when the electrical contact ismoved away from the terminals. The tip 36.,of leg v2!! enters `disc'lF. However, the end 34 terminatesshort of the lower surface of the disc F so that it provides no obstacle' to the movementof the roller.,

The leg 24 of spring C has anrofl'set therein so that a portion of the spring'engages an'upper portion `of the flat body 20,)an`d a portion ofthe same leg` engages a lower portionY of the trigger body so that the leg 24 cannot jump fromL-the trigger;

` `It is to be noted that the electricalbridging disc F is pressed downwardly on the base and is moved into engagement or away from'engagement with the electricalterniinals D andE solely by the spring C.'- y *i f l e The rigidlstationary electrical terminal D made of a single piece of electrical conducting metal has an externaleye portion 38 to which an electrical lead wire may be attached. The leye portion merges with a central fiat portion`40 which'interts with a-"complementary opening f 42 in the baseA, and the main contactv surface 44 of the terminal 'is of a 'greateriwidth than the width of the intermediate portion40. The aforementioned structure enables the terminal D to be readily inserted in the opening 42 so that shoulders :.45 and 46 abut against the base, and then the outside ends 41 and 48 on the intermediate portion 40 are expanded into engagement with an outside portion of the base. Hence,-the terminal is held in position. `The main contact portion 44'of the terminal abuts a portion of the. vertically extending side wall so that the force .exerted by the bridging disc F cannot move the terminal.

The flexible stationary electrical terminal E which is made of suitable electrical conducting material is rigidly held in thebase A in a manner similar to that by which .xecl terminal D is held.

.The terminal has an eye in its outside extending portion 50 to which an electrical lead wire may be attached, as by soldering. .The eye-portion 56" `merges with a central fiat portion 52, vthe latter interiits lwith "a complementary opening 54 in the Vbase A. The central portion 52 is integrally connected with a widened portion 56 that provides V f freely move to the right;v From the intermediate.

portion 62 is the contact disc engaging portion 66 which has a4 lower extension isthat abuts the insulating base in the groove 69, and the extension 68 serves toy support the end of the flexible extension 66.1 'Ihe disc'engaging portion -of thefexible terminal 1E is curved to` complej mentarily engage a portionfof the curved-bound-r ing surface of the bridgingdisc c It should be noted lthat in the`position illustrated in Fig. 1, the flexibler arm 66- is spaced from a wa1l10,.and the connecting portion 62 is also spaced .ffromits limiting` wall' 64.` However,

' when the triggerisoscillatedto Aclosed circuit position, the roller bridging disc F rstengages the fixed terminal D beforeit engages the flexible 4terminaLand the arc created when the electrical Acircuit is opened occurson a portion of the contact 66 which is not the final surface engaged because-fthefdisc F pushes the contact 66 against the "wal1f10. In rvotherwords, arcing occurs 'between "auxiliary portions of each terminal which are lnot the flnal or main contact surface. .1

, Repeating the above in other terms, when` the `circuit is to be broken, it is to be'noticed that directcontactwith bridging` disc'F'for a short distance, -and the breaking-arc will take place near the end 45 of the fixed terminal D.

, It is to be particularly observed thatthe lower- Amost flat portion 13 of disc-F adjacent the curved bounding surface'rolls upon va narrow' ledge' 15, thus minimizing the friction Abetween vkthe base and the disc However', the disc F both rolls 'and frictionally engages orwipes thev stationary `rigid -and flexibleterminals D and E. This frictional action smooths or erases any irregularities orf' obstructions due to oxidation,` pitting, or dirt so ,the ,contact resistance is kept low; Oxidation, pitting, or dirt .generally results in high contact resistance between the terminals and the bn'dg.- ing memben y, l

In order to avoid any ashovers between the spring C andtheiiexible terminal E, a thin piece of insulationlmay A be placed between ksuch elenents in a manner not to obstruct the operation of the switch.

g theflexible vterminal contact '66`will follow in When the disc F is .in open' electrical circuit- 'with the contact surface of the fixed terminalD,

and the wallis-turned'at right angles toilirnit the .movement of Vthe disc F in its open circuit Aposif5.1

tion.

, A metal cover 'il-may be placed over the switch and a control shaft 16 may be suitably journaled to the cover. The cover may be groundedror connected toA a point of zeropotential in order -to reduce any stray electrostatic linesofforce f or any stray electromagnetic lines of force. The eccentric 21 which engages .oneY or theother of the spaced or bifurcated members 25, 26 issuitvolume control as shown in my prior `Patent No.

2,057,829where a single vcontrolactuates both the switch andthe volume control but wherein actuation of the swich to closed circuit positionis Veffected by a relatively small movement of "the control in one direction and permittinga relatively-large'movement of the control inthe same y direction without affectingvthevoperationfoffthe lswitch. .r

If it should be desired to have the bridging Vdisc slid into'positlon'instead of rolled, la notch may becut into'the flange ofthe insulating bushing; G so that armv 28 of spring C lies `w'lh"the` notch. This will lock the electrical bridging disc and the leg of the torsional spring'together.'

` Referring now in greater detail to the 'ni'odi-i cation illustrated -in Figs. `7 to 14, I disclose a movable electrical bridging member, generally designated as F1, which has an irregular curved bounding surface. l Y 'Ihe electrical conducting bridging memberhas lan irregular bounding surface, which is arcuate from the points b to c and e to f. The arcuate surface b, c has a radius whichis of equal radius to the arcuate surface e,f. From the point' bis a tangent which extends to the left as Fig. I16

is viewed and which defines a portion of the fiat bounding surfacev a, b. A similar arrangement is made from the point cwhich defines the fiat surface d, c. Tangent surfaces fr om'the ends of the arcuate surface result in thefiat surfaces f, a and e, d. Hence, the bounding surface y and a flat surface f, a which is substantially at` right angles to the surface a, b.

The bridging member F1 functions as follows: When the circuit is partly closed from the initial 'position of Fig. 1l, it will be seen thatfthe bridging member F1 is rotated slightly so that the flat surface c, d engages and wipes the xed contact D, andthe arcuate surface e, f fits into the bowed portion of the flexible terminal E (see Fig. 12). In the closed circuit position, as illustrated in Fig. 13, the curved surface e, f of lfhe bridging member F1 is still yin contact withthe flexible terminal E, and the ifiat surface c, `d has wiped along the fixed contact D.

It is .+o be noted, however, that the roller or bridging member F1 is partly rolled into position, and in Fig. 13 the bridging member slides into position. When the switch is actuatedto.

open the circuit, then the arc is broken so that portions of the bridging member which are not used as the main contact surfaces take the arc. The are will be taken by point c and a portion of the iiat surface e, d as the bridging member reaches the curved wall stop portion of the basev and adjusts itself as rolling into its nest so that it is in a position of Fig. '7 or 11.

In Fig. 10 I show a shield of a conguration t0 nt Abetween the flexible terminator th'efnxed teg." minal, and it'lies within themainsurfaceof the base chamber. The shield has an-"elongated fopening therein .which Aenableslfthe' insulating bushing Gtow'freely slidei'back'and' forth;

E and the metallic spring C. This dielectric shield reduces anyy danger' of a flashover occurring -be- .tween the live terminalsE and the metallic spring,

- Thus, Vit is seen that the above-detailed de-V -fscription particularly applies to theillustration vofrFig.wherethe dielectriczor'insulatlng shield -H-ls disposedbetween theliverflexible terminals particularlysince the distance between the spring and if.V a" iiashovershould occur,' theY -potential difference `between thefcoil portionV oil the :spring and the fixed terminal must `berelativelyY large. 11

and thenexible memberis comparatively small.i f 16A stractureeut1med;in rigs;k '1 toV mythe stamped-- out electrical bridging member is shapedlto pro# duce both a rollingand1 a 'sliding action whereby pitting -or excessive burning'. `The clean contact surfaces "lare" features whichl fmust be present in -the switch so that 'the effective life -of the switch I is long; and the clean1main`- surfaces 'also reduce thecont'act `resistance between'the "stationary terminals and the movable bridging member con- . Although my invention has been descibed finconsiderable" detail,` such.' description I is intended] as"i llust'rative 'E 1 rather than l"lirn`iting,"-` since the invention may? be ,variously embodied, and thev scope offtheinventionis K-toybefdetermined aS- rk i f a stationary, electrical terminal and a flexible, '1

electrical terminal, lan electrical bridging vdisc adapted .to'engage said terminals whereby ythe electrical circuitwill be closed and -to move away from saidv terminals whereby the'electrical circuit will be opened, said disc having an openingtherin, a small cylindrical insulating -bushinginter- -tting with the opening/in said disc, a flange on said insulating bushing adapted to engage the upper surface of said bridging disc, a forked actu-5 ating trigger pivotally mounted, a', torsional spring having one end connected ,to said trigger, and the other end bent at an angle whereby the Abent end 55 extends into the insulatingbushing, a portion `of said spring pressingupon the. insulating bushing,I

flange therebyfpressing said bridging memberinf a direction jtowazjds the base, and said-spring adapted to directly move said bridging disc in one direction or the reverse direction depending upon the movement dead center position.' 1

A2. A snapswitch comprising a base, a, plurality of spaced electrical terminals mounted thereon,

, a rotatable disc-likemetal bridging member free@l 1y movable across said base intoand out of en? gagement withys'aidterminals, said bridging memj ber being provided with an axial opening per- .Y

pendicular to said base, a pivoted 'trigger connect-f ed to said base, and a torsional spring having one fend connected tothe triggerl and the other end bent to project loosely into 'said' opening, said spring being adapted to rapidly roll said bridging member into and out of bridging contactv with said terminals as said trigger `is moved back `and offsaid springbyond its y* avplane substantially parallel lto saidf" base, ,one

forth, said spring being the only means forr hold` ing thev bridging member in position on the base andfor actuating it. e

3. A-snap switch comprising a base, a plurality of spaced electrical terminalsmounted thereon,

a rotatable disc-like metal bridging member freely movable across said base into and out of engagement with said terminals, said bridging member being provided-with an Vaxialopening perpendicular =to said base, an insulatingbushing disposed in said opening and projecting .above the bridging member, said bushing being provided `jwith an axial opening, a pivotedrtrigger/connected ,tol saidbase, and a torsional; spring having one endlconnected. to the triggerand the other Yend bent to project loosely into saidbushing opening,

saidspringbeing adapted to-rapidly roll said bridging memberinto and out of bridgingrcon- `tact with-said terminalsas said trigger is moved `back and forth, said'spring beingtheionly means for holding-the bridging member4 imposition on the base and for actuatingit.v y i Y.

, 4. A snap switch comprising a-baSe, a plurality of spaced velectricalterminals mounted ',the'reon,V n tarotatable disc-likemetal bridging member. freelyv movable across said base into and'out or engagement with said terminals,; said bridging memberbeing'provided with an vaxial.,openingper- 4pendicular to said base, anginsulatingbushing disposed in saidopening and provided.atits .outer end with a flange extendingc radially-v outwardly across the Abridging member.; saidV bushing being provided with an `opening perpendicular Y,to saidy base, a pivoted trigger connected to said base, a substantiallyv VU-shaped torsional, spr'inglying in end of said spring'being plvotally vconnected to .the trigger andthe other end being bent sub-v stantially at right 'angles-,and projecting loosely into said bushingr opening: said spring being adapted to rapidly roll said bridging member e into and outof bridgingcontact with said termivnais as said'trigger is moved back and forth, said f spring being the only means for holding the bridgt ing member in position on the base and for actu- 5. Asnap switch Acomprising a base, a plurality of spaced electrical terminals mounted thereon,

.a rotatabledisclike metal bridging member free-- lymovable across said base into and out oiy en- Y gagement with said terminals, said bridging mem-4 ber being. provided withan axial 'opening perpendicular to'said base, a pivoted trigger conc nectedvto said base,and a torsional spring ,having one end connected to the triggerand the other end bentito project looselyy into said-opening, said spring being adapted to rapidly roll said bridging member intocand out of bridging `con` tact with said terminals as said trigger is moved back and forth, said spring being the onlymeans for holding thefbridging memberlriposition` on thek base andjfor actuating it, andl said base base provided withl arecess, a-"pairof ,spaced lelectrical terminals mounted insaidvbase at', one endofA said recess, a. rotatable disc-like lr1`u eta.l

bridging member disposed in said recess and Ireely-.movable .thereacross into and out of engage- .K ment with said terminals,; said bridging member. being provided withvan axlal'opening perpendicular to said base, a 4trigger pivoted to said base at one side of said recess, and a 4torsional spring :having ,one end. connected `to the triggerl and the land terminals defining a guideway for the bridging i memben Y. l u

6." A snap switch comprising a molded insulated

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