US2844672A - Electric outlet socket and plug - Google Patents

Description

y 22, 1958. M. SAMBONET ELECTRIC OUTLET SOCKET AND PLUG 2 Sheets-Sheet 1 Filed July 6, 1954 INVENTOR.

July 22, 1958 M; SAMBONET ELECTRIC OUTLET SOCKET AND PLUG Filed July 6, 1954 2 Sheets-Sheet 2 INVENTOR. 4 Q44, {w

Abba-0L f M United State atent O P ELECTRIC OUTLET SQCKET AND PLUG 5 Mario Sambonet, Milan, Italy, assiguor to Italb-Rizzieri, Milan, Italy ApplicationiJuly 6, 1954, Serial'No. 441,455 Claiins priority, applicationltaly July 3, 1953 8 Claims; (Cl. 200-51419) This inventionrelatestoan electric outlet socket and plug, and more particularly itrelatesto a new' and im} proved electricservice' device comprising an outlet and a companion plug of the type in which the above two members ofthe device are designed for mechanical inter engagementan'd for completing a circuit by'acombination of axial and of rotational movements impartedto the plugin respect to and inside the socket member of the device":

It: is an object of'this invention' to provide'a newan'd useft'll electricoutlet of the above type; having means for instantaneous closing and interruption of the current to: prevent any sparkingbetween the contacting me'mher's thereof and therefore any inconvenience I and damage caused'thereby; as-wellf. known bythose skilledin" the 811.

A nother object-of this invention isthe provision of" a" plug; and of a. socket member" of new and improved coir-" struction and designed; to cooperate with said plug for inter-engagement such: aszto'prevent accidental separating oft'thevparts by pulling on. the service cord or from other causes; even; if"; the electric" circuit is interrupted, and therefore: the i provision of w new -and improved socket andizplugz device: which :mayabef usefully; used' asa=-p1ain switch device for turnin'gfontandlsotf current with'out sep: arationrandipreventing.accidental-separating of thepa'rts 40 thereof;

Anstillrfurther; object: of. this inventioniis ito provide a newgandtimproved electric: serviceoutlet of ithe chatacter referred to.above;:whichzdoes not tleave-exposerl ahy tefl" minalsswhich :might-be contacted :by; a user; :by:chi"ld'ren':- andother; carelessroneslandl thus :causezshock, injury, andd ma e Another. object \of: this :invention: .is IOPI'OVld an; electr tric, service outlet oftthe: type described with-a socket of such construction that as plugr-member partially; inserted thereinto, may be turned ifrom-r a: first: position ini whichsaid membenmay beinserted inrand removed from said socket-to a secondposition; in which said socket and plugzi membersare-mechanically inter-engaged for preventing accidental, separating, of. said; parts, while. the :circuit' is stilhinterrupted, that may be-further.turned from said last-named position to a third position. in which 3' certain contacting members provided thereinto cause the circ'ui't to be completed,..that maybe turned back from-vsaidthird PQSition to saidwsecond positionv for having-the said" circuitbroken, and thatcomprisesmeans for preventing-Vt accidental tturning backv of.- then-plug to. said-first- -position-== (in-gwhich the said plug,is subject to possible removal-)1 wh'enltheinterruption. only of the circuitis .desired.

Afurthervobjectofnthis inventionis to provide ail- '65 electric service outlet of the above-character in which auxiliary contacting 5 devices and. members are'comprised forv having auxiliary ,Wires connected thereto, particularly 1 butnot exclusively forhavingthe metallicbodyfofthe servicediapparatus -:.(lamp-,, -radio or 'televisi0n fset,'- electric razor, ,electr'ictrypewriten and soon) ..conne cted to the ground for safer and better operation thereof.

, 2,844,672 Patented July 2 2, 1958 A still further object of this invention is to provide a device of the above character wherein an alternative embodiment of the plug member according to the inventioIi-m'aybe used as'a removable wall'la'mp', for example, i. e. forr'erriovably supporting and operating an electric lamp at the position at which the cooperating socket member is mounted, in a; wall of a'buildin'g, for'e'xample.

After all, it is an object of this invention to provide a new and improved electric service o'utlet and plug'de vice, the 'parts'of which are of simple construction, readily assembled and which can readily be coupled and uncoupled.

With the foregoing and other objects" in View which will appear as the description proceeds, the" invention consists: of certain novel details of construction and combination of parts and members hereinaftermorefully described and pointed out in' the claims, it' being understoodthat'changes andvariou's modifications and alternations rrr'ay' be made in the construction and in the ar range'ment' of parts without departing from the spirit of the invention 'as defined in the appended claims.-

In generahl attain the above principal objectsof this invention'by providing a novel construction comprisinga receptacle having a shaped opening, a plug' ha'vin'g radial contact arms and designed to passth'r'oughsaid shaped opening and intosaid receptacle when in one of'deter min'edfiist' angular" positions in' respectto said receptacle, resilient contact surfaces inside said receptacle and arranged therein" for being contactedbysaid contact arms as said plug hasbeenturned'inside said receptacle from one of "said-first positionsto one'of'detei'niined third angular 'positionsfa'n'gula'rly Well spaced from said first-positions; and-foi'bein'g well' de't'ached from at least one of said" contact arms as said plug" is kept at one i of determined second positions intermediate to' said first and third positions, means for preventing' said plu g to be turnedb'ackfronrsaid seco'n'dposition to said first position except upon' exerting onsaid' plug a v'oltintary determined'action, and a resiliently"supporfednon-conducti've'm'emb'er arranged on at least one of'said-resilient contact surfacesand arranged 'in respectto" said surface and to the plugscontact' arm designed to cooperate therewith-for having said-surfaceinstantaneously detached and spaced-from said contact arm and to"beinstantaneously inserted between said contact members; v

These a'nd other advantageous objects and features" of this in'vent'ion will be fully understood by" a consideration-of the following detailed description of a preferred form ofern'bo'diment thereof when taken in conjunction with the accompanying drawings, forming an essential component 'ofthis specification and wherein like numerals are'empl'oyed' to designate like parts throughout the sev-- eral figu'r"es; and in which:

Figured a perspective explodedview of the'plugmember and'the receptacle member'of an electric service" outlet according to'one embodiment of the invention,--inwhich the plug 'member'is brought near to the receptacle m'e'nibe'r'in' said first angular position for engagemene thereinto.

Figure2' is a partially sectioned exploded side view of lug-member and receptacle member," the section being-- takeii 'on'line 2- 2 of Fig. 4.

Figure 3 is a partial side view of a modified form of embo'dinient'of'aplug member produced according to the invention and'designedto support and to electrically "con ncta'lamp'j p Figure "4'is a cross-sectionalview of members of Fig'. 2, in which the said-plugmember appears as beinginsert'ed' into butnotmechanically and electrically connected to the said=receptacle'-member;' the said cross-sectional view he ingjtaken on line 4= 4'of Fig. 2;

Figures 5, 6 and 7 illustrate in a rather diagrammatical manner the operative parts of members illustrated in Fig. 4, in several various respective positions during the turning-on and respectively in the said third position and during turning-off of current; and

Fig. 8 is a sectional view of the embodiment shown in Fig. l, the section being taken on line 8-8 of Fig. 4.

In general, and referring first to Figs. 1 and 2, an electric service outlet device according to this invention comprises a plug member (Fig. 1) having a handle portion 11, preferably of non-conductive material, a cylindrical plug portion 12 of non-conductive material and radial contact arms 13 and 14 of conductive material, chromeplated brass for example, or other suitable metal or metallic alloy known in the art, radially extended from the force end of said plug portion 12, and a receptacle member (Fig. 2) formed by a casing Ill preferably of nonconductive material, having a shaped front opening comprising a central circular portion 15 designed to allow passage of said cylindrical plug portion 12 and radial slots 16 and 17 likewise designed to allow passage of said contact arms 13 and 14 respectively of same plug.

Preferably, the said contact arms 13 and 14 and the said slot portions 16 and 17 are symmetrically shaped, so that the said plug may be inserted in said receptacle in any of two first angular positions at 180 one to the other, in which the said arms 13 and 14 are aligned with said slots 16 and 17 or 17 and 16, respectively. In the forms of embodiment shown, the electric outlet device according to this invention is designed for connecting circuits comprising two conductors only, and it is therefore provided with two contact arms only. A three-phase circuit however may be connected.

In view of the described shaped opening of receptacle member and of the cross-sectional shape of the plug member comprising the said contacting arms, the said plug member 12 may be passed through said opening and inserted in said receptacle by an axially directed movement as indicated by straight arrows A upon positioning said plug in said first angular position in respect to said receptacle.

According to the gist of this invention, engaging and contacting members and parts are provided in said receptacle member for having said plug and receptacle members mechanically connected upon completion of a combined axial and rotational movement indicated by U-shaped arrows B. Said movement comprises firstly a further axial forwarding of the plug 12 inside said receptacle, overcoming a slight axial elastic opposition, then a small clockwise rotational movement and then a small axial backward movement due to said elastic opposition, i. e. the mechanical connection of said plug and receptacle member may be actuated by imparting to said plug a socalled bayonet action. As said plug has completed said movement B, the electric circuit is still interrupted, i. e. at least one and preferably all contact arms are still kept well spaced from the contact surfaces arranged inside said receptacle member, and which will be fully described below. For having the circuit closed, a further angular clockwise movement C must be done. By simply turning clockwise and counterclockwise said handle portion 11 of plug member the described device according to the invention may therefore be advantageously used as a plain switch, as desired for example for having the current on or off respectively without mechanical and material separation of the plug member from the co-operating socket memher.

In Fig. 2 and partially in Fig. 4 a preferred construction of the plug member is shown. Referring now to said Figs. 2 and 4, the said cylindrical plug portion 12 is actuated by a tubular member of non-conductive material, of a type currently used in production of electrical devices of the kind, having an out-turned flange portion 20 made integral to the rear end thereof and designed to be removably connected to and to close the front open end of the said handle portion 11 of the member, said handle portion being preferably constructed in the form of a hollow cup-shaped piece of non-conductive material.

Inside said tubular plug portion 12 two metallic parts 21 are symmetrically constructed and arranged, in Fig. 2 only one of said parts 21 being shown. Any one of said parts 21 is provided with a fore radial extension forming the said radial contact arm 13 (or 14), with a rear radial extension 22 bearing a screw 23 for connection to a conductor at the terminal of the service.

cord leading to the serviced electric supplied apparatus. The said parts 21 are kept in the described arrangement and electrically insulated by co-axial core members 24 and 25 of non-conductive material, provided with longitudinal recesses for said parts 21 and with head outturned flange forming portions 26 and 27, respectively, on which the end portions 22 and 13, respectively, of said parts 21 abut. Said core members 24 and 25 are firmly connected head-to-head in their abutting relationship with said parts 21 by an axially arranged metallic rod 28 having an enlarged head portion 29 positioned outside of and abutting on the external flanged end 27 of the core member 25 and having a screw-threaded portion at its other end, on which a nut 31 may be tightly screwed.

As shown particularly in Fig. 2, the said portions and parts 22, 23 and 31 are arranged and protected inside the hollow cup-shaped handle forming portion 11 of the plug member of the device. The said portion 11 is further provided with a central hole 30 designed for passage of the end portion of a conventional service cord the wire conductors of which may be firmly mechanically and electrically connected to the parts 21 by means of said screws 23. A third wire conductor comprised in said cord, if any, may be connected to said rod 28 by means of the said nut 31, for grounding the metallic frame or body of the serviced electrical apparatus. The terminals of said apparatus may therefore be electrically connected to the one and respectively to the other of said contact arms 13 and 14 and the frame structure or body thereof may be electrically connected to the externally arranged head 29 of said rod 28.

According to the alternative form of embodiment of said plug member, shown in Fig. 3, in lieu of said cupshaped handle forming member 11 a tubular member 61 of non-conductive material is provided and connected to an out-turned flange portion 63 of a tubular plug portion 12 having contact arms as above described in referring to Fig. 2. By means of extensions 62 of said flange portion 63 a threaded socket 70 may be firmly supported inside said tubular member 61, said socket being designed for having a conventional electric bulb or glow lamp (not shown) screwed in, according to the present day equipment. Said screw-threaded socket 70 is electrically connected to one of said contact arms 13 or 14 of the plug portion and the other one of said contact arms is electrically connected to a member 64 of conductive metal or metallic alloy arranged inside and at the bottom of said socket 70 and designed for axial abutment and electrical contacting relationship with the centre terminal of the glow lamp.

Plug members produced according to the invention and constructed as shown in Figs. 2 and 3, respectively, may be alternatively connected for operation to a receptacle member of the type which will'be now described in detail and which is shown in Figs. 2 and 4 to 8, in which the parts appertaining to the plug member cooperating therewith may be indiscriminately referred to either of said alternative forms of embodiment.

According to Figs. 2 and 4, the said receptacle member 10 is formed by a cup-shaped piece of non-conductive material, having a front face forming portion 40 at the centre of which the said opening 15-17 is provided.

Said opening is surrounded by an externally screwthreaded collar 41 the axial dimension of which is less than the spacing betweenthe radially extended-1 contact arms 13 and 1 4 of the plug members designed, to, cooperate therewith and; the flange, portion 2,0 or 63' of said plug (see Fig; 2 or- 3 respectively). About said collar 41 an annular member 42 aybe screwed on, if desired; for-having a glass or other-inaterial-made 6 tional' covering plate 43; secured upon said front face portion 40 of the receptacle body.

The various contact surfaces and; other operative devices which are arranged inside said receptacle body are preferably supported by a circular plate 44 ofnon con ductive; material removably positioned inside said receptaclebody and firmly connected thereto by means or two or three screws for example, in abutting relationship with an internal step, 45jprovided in the side walls of said body. Said circular plate .44 aetnates a partition dividing the interior ofsaidbody in a forechambelf (b tween said plate and the face forming portion 40 of said body 10) in Whichall contacting and circuit breaking devices are housed, and in arear open chamber inwhich the several means for connection to electric current sup; ply conductors and to the optional1grounding conduetor are arranged;

In the form of embodirnent shown and as it may be clearly understood by a particular consideration of Figs. 2 and 4, the, inner operative devices comprise a first resilient contact member 461electrical1y connected to a first-binding -screw 47, an oppositely arrangedlsec; ond resilient contact member 48 electrically connected to a secondbinding-screw 49 andan auxiliary axially arranged third resilient contacting member 50 electrically connected to a third auxiliary binding-serew 51 (Fig, 2 While t a contacting m mbe s. ..and48; a d e, binding-screws 47 and 49v respectively connected thereto are arranged; respectively i insidev and. outsire said f A o mi mb r. 4.4fm. av a mp1e. an: s'trnction of the device the said auxiliary contacting member'SO may be supported outside said partit on;

as: shown in Fig. 2; the saidpartition forming member 44 beingprovided'with a central openingthrough which the end" portion ofysaid' contactingmember 50 is exposedinside said member 44' facing the,opening of therecep tacle. I

Said contacting member 50 is made in the form of abent strip of resilient conductive metal and it is arranged andshaped, as shown in Fig. 2, to be contacted} by-theenlarged headportion 29 ofsaid metallic rod 28' of the plug member'as the latter is axially inserted in direction-A (Fig; 1) through the sa-idopeningg15--17';

The-contact between-said parts 50and29-occurs before the; contact arms 13 and 14' are fullypassed through the slots- 16 and 17, so that during theendportionof theforward motion in direction A of theplug: 12 a'resilient opposition by said member 50 occurs. Further; as the: said plug is nearly fully inserted inthe receptacleand upon connection of rod 28ato the-frame or body ofthe serviced apparatus and of binding-screwSl' to ground;

the: said apparatus body onframe is properlygrounded. About the said opening Hand on the inner face-of collar 41E small projections-w65 'made integral with said collar are provided: near the sidesof said slots 16'and' 17 (Fig; 2) For having-the said plug'12-'-1'4:free to rotate. inside the receptacle, it is therefore necessary to prosecutetheaxial forwarding-motionof saidplug in direction A, overcoming the opposition-ofresilient contactingsmember 50; until the rear ed-gesof said contact arms 13 and 14 may pass over the said projections 65; As saidconditionissatisfied, saidplug may be-rotatedand 'assaid-contact arms 1'3 and-14 pass-over said projections,- the said plug may: beslightly moved outwardly direction opposed to'A by-thespring action of saidcontactingmember SO: Attthispoint the said second-positionis attained, 'asthe two plug vand receptaele=members become--mechani-eally inter-engaged; and- 'the--saidp u flim y e. r ate n di ec on C"(.t t e id-third po t o ppo ed to kt s condp sitionlin the angular space defined by the abutment of contact arms on said projections65; which act as stop members preventing said plug from reaching the said first posii tion in which the mechanieal inter-engagementi's,normore made sure and from which said plug maybe drawn, the socket. Whenit is desired' to have the 19 .1 remoyed from the receptacle, 'by a slight rotational forcing on the external handle portion 11' of the plug member, the a act. s 13 and am na-be pa sed ha kion. the projections .65; which are, preferably round shaped; as shown in Fig; 2. It a more positiye prevention ofacci} dental turning'back ofthe plug member untiij' the filrst position is desired, saidprojections 65 may be shaped'to have sharp step forming flanks or saw-tooth shaped' se that; a positive pushing action on the plug handle must be exertedfor having t e Saidcontact arms frlee tobe rotated oyer'said projections.

Preferably, one of the contacting members designed to co-operate with the contact arms of the 'plugismade for havingthe-saidplug resiliently kept in the said sec: ond and third positionsg and the other one is associated with the said device provided for havingthe circuit in; stantaneously closed and-1 broken. As shown in Figs. 4 m7; the contacting. member 46 is; actuated 'by astrip-of resilient conductive metal and it is provided-with a recess portion52 designed tocomprise the outer'edge of'a contact-arm 14' (or 13) as said plug is rotated to from-the firstposition- (Fig-p6), the 'said recess 52 hav{ ing rounded flanks allowing the comprised contact arm to beeasilymoved by impartinga little rotational force to theplug. Furthen the said-contacting; member is shaped at both its side portions Gin-respect torecess-52 to abut-onthe contacnarm 14-1 Figst-i and 7") as soon; as thesaid plug is rotatedfrom itsfirst position to' its second position, and to resiliently urge the said armin the second position, i; e. in the abutting relationship with the .inner rflankof oneprojection 651- I The second contacting member 48 is alsoactuated by a; bent. strip of. resilient conductive metal, and isar ranged in opposition-to the; said first contacting member 46; The contacting surfaceof saidfmember-48 is-partially; covered by a fiat member 53 made of nonwonduetive material and provided with; an. opening. 54 positionedto: allow: the passage, of the contacti arm. 13; (or 14:) and to. havelhe, outer. edge thereof in contacting-relationshipwith saidmontacting surface astheother contactrl'4 (or-"- 13) reaches therecess: 52'of otherv contactingmmem'ber 46;,v i. e as .the saidplugis utinitssaid-third position; The said nonsconductiveg member: 53.; is resiliently; urged; against. theta'xis' of the .devicen'by. two symmetrically-ar fing dwcompressionworking coil;springsSS and 56-, or; by: otherpequivalentz spring-:means,-.- and the ends of; same. non-conductive. memhen. 5.3 -slidably. .abut' on inclinedsurfaces 59 and 60 of non-conductive portions 57 and-5'8 respectively; made, integral with the structure-of: the receptacle, preferablywiththe said member-44, the said portions157 and: 58.. acting furtheras stop mem-hers for" confining- .the' movement of'sa-id' non-conductive member 53:; urged towards-the devicesaxis by said spring means" freely removed from the receptacle by plain pullirigQa-ctionjj exerted'on'thehandleportion thereof 'in a direction op o.- site to A;( Fig.' l). As above descrijl'iedg he condit on ofmechanical inter enga'gementoccurs in the said .s'ec,-

'-ond='pos'ition;*in -whieh saidcontact arms have been passed beyond the projections 55 (Fig. 2). In such position the plug is not subject to accidental separation from the receptacle, by pulling on the service cord, for example, or from other causes. Further, in such position the auxiliary grounding circuit is yet closed by the contacting relationship of enlarged head 29 of rod 28 of plug with the said contacting member 50 (Fig. 2) while the power circuit is still interrupted because at least the contacting member 48 does not contact any of contact arms 13 or 14 of the plug.

Supposing now that the plug is: further rotated for example in direction D (Fig. the contact arm 14 of the plugs contacts one of the side portions of the contacting member 46 while the other contact arm 13 presses on the surface of the said non-conductive member 53 urging it against the said contacting member 48. As soon as the edge of said contact arm 13 faces the opening 54 of said non-conductive member 53, the said third position is now attained and the latter member may be instantaneously brought back towards the axis of the device, and the outer edge of said contact arm 13 is therefore instantaneously brought in full contacting relationship with the contacting member 48 (Fig. 6) and the power circuit is instantaneously completed, as desired. The seating of opposite contact arm 14 in recess 52 of opposite contacting member 46 co-operates to maintain the plug in its said third position and prevents lateral thrusts on the said non-conductive member 53.

Supposing now that turning-01f of the switch actuated by the device constructed according to the invention is desired, and that the plug is caused by the user to rotate in direction E (Fig. 7) towards its second position, the circular motion of the outer edge of contact arm 13 urges the said non conductive member 53 to tangentially move leftwards (in relation to the embodiment shown in Fig. 7) sliding with its left end along the inclined surface 59, and pressing the coil spring 55 while the said outer edge of contact arm still contacts the surface of contacting member 48 through the said opening 54 i. e. while the power circuit is still closed. At a certain point of such movements of parts and members, and nearly at the position shown in Fig. 7, by the progressive lowering of said non-conductive member 53 (due to the sliding thereof on surface 59) and by the increasing inclination of outer edge of contact arm 13 (due to the rotation thereof) the action of the compressed coil spring 55 may insert the said non-conductive member 53 between said contact arm 13 and said contacting member 48, in a position substantially as shown in Fig. 5, positively spacing said contacting means and materially positioning a non-conductive solid material therebetween. Said movement of said non-conductive member 53 is accomplished in a substantially instantaneous manner, and the most desirable instantaneous breaking of the circuit and cutting of any spark or are are therefore advantageously attained.

Preferably, as shown in the described figures, the above parts are symmetrically arranged in the device and the third position is made at 90 to the first position. In view of such features the electric service implement described may be operated either as a connecting means and as a simple switch by rotating the plug in the one or in the other direction, without prejudice of its operation and of its durability. Of course, while in the described figures the said contact arms 13 and 14 cooperate with the contacting members 48 and 46.1espectively, said cooperation may be immaterially accomplished with contacting members 46 and 48 respectively.

While I have described and illustrated but one form of embodiment of this invention and but one modified embodiment of the plug member thereof, it will be readily understood that others can, by applying current knowledge in the art, make several alterations and changes in the construction of the device according to the invention and of the members, parts and details thereof, without omitting features that fairly constitute essential characteristics of this invention as set forth and defined in the appended claims.

Further, an electric service socket and plug produced according to this invention might be readily further improved by adding other servicing devices and/or safety means. For example, the receptacle body may be provided with two or more sockets designed to co-operate with two or more plugs, as described. One or more fuses or other safety devices might be connected in the power and/or grounding circuits and arranged in the receptacle and/or in the plug member or members. By applying current knowledge in the art, a plug member may be devised in which a plug portion, designed to cooperate with a socket member according to the invention and preferably comprising the described parts 12, 13 and 14, may be structurally .and electrically associated at its outer portion (in lieu of portion 11) to a socket for conventional plugs, to adapt the invention to the present day equipment.

Such variations, alterations and additions should and are therefore comprehended within the meaning and range of equivalents of this invention, and what I claim as new and desire to have protected by Letters Patent is:

1. An electric outlet of the type described, comprising a plug member having a cylindrical plug of non-conductive material, conductive contact arms radially extended from the end portion of said cylindrical plug, a conductive head axially arranged at the end of said plug, and binding means to connect said contact arms and said conductive head to power conductor connected to the serviced apparatus, and respectively to a conductor grounded to the body of the serviced apparatus; and a socket member comprising a receptacle body of nonconductive material having an opening comprising a circular centre portion and radial slots extended thereabout for passage of said cylindrical plug and of said contact arms when in one of determined first angular positions in respect to said socket member, a resilient first conductive contacting member connected to ground positioned at the center of said receptacle body to abut on and to resiliently exert an axial opposition to the said plug on the conductive head thereof as said plug is axially inserted into said receptacle body through said opening, power resilient contacting members connected to power wires positioned inside said receptacle body about the position of said plug as inserted thereinto and to be contacted by said contact arms as said inserted plug is rotated to a third position angularly spaced from said first position, stop means co-operating with said resilient first contacting member for removably keeping said inserted plug in a second angular position intermediate between said first and said third angular position and in which at least one of said contact arms does not contact any power contacting member, a non-conductive member movably supported inside said receptacle body and positioned between one of said power contacting members and the position of said plug as inserted in said receptacle body, an opening in said non-conductive member designed for passage of one of said contact arms as the said plug is angularly positioned in its said third position and spring means for having said non-conductive member instantaneously inserted between said power contacting member and the contact arm contacting thereon as said plug is caused to rotate from said third position towards said second position, and when said contact arm is still in contacting relationship with said power contacting member.

2. An electrical outlet device, comprising, in combination, a socket member; a plug member insertable into said socket member in a predetermined first position and turn able therein in inserted position about an axis from said first position to second and third positions; locking means provided on said plug member and on said socket member for mechanically interlocking said plug member with said in transverse direction from'said axisandmoving in a circular path wh'ensaid-plug member is tur-ned about said axisaandi-second contact means fixed to said'soeket-m'emi berand beingspaced 'from1='saidaxis in' transverse direcration? substantially' thesame distance as said first-coi1tact imeans a-nd being located in -s'aid path 'of said' first contact t imeansgisaid second contact ineans beingspaced'from said rconta'ct-iimeans' in =fsaid first and second positions 1 of said zuplug memberi and being in "Contact with 'saidfirs't" Contact ameans 'in said third position ofsaidplug-rriember-te establish an=electrical contact -withsaid first contact means.

i 3. An 1 electrical outlet device comprising, in com-binati'on; ahollow socket member ha'ving-a'front plate formed -with an opening I therethrough and with at least one slot extending: through said plate in transverse direction-from i-said opening; E said front plate having arear-"-iace';-a plug wmem'ber having a front portion insert-able through- -said rope'ning into said' socket member-in a predetermined first vmosition and turn'able thereinininserted position about an.- axis'from -said first position to second and thir'd posi- :ctionsydocking means fixed 'to said frontpor'tion of said;

.iplugzmember and :proje'cting-in trar1sverse '-dir'ectioi'1*' from saidfirst'positiongsaid locking means having in adirection -inormal-torsaid axis 'anoutline matching said s'lot in=said :fr0nt-. plate a" so .--that said locking means are insertable ithrouglr. said slot in" said first 1 positionof said =plug' mem-f z bemsaid locking means havingan abutting-"face subs'tanrtiallyi normal to said axis abuttingagainst said inner face 'of said::frontplate in said second and third positions of ="saidft plug member-' to interlock -said plug-1 member with r saidzfsocket-i imember; -first contact means 1 fixed to "said iront portion of plug member being spaced in transverse dire'ctionrfrom saidaxis and' 'moving'in a 'circiilarpath :wh'em saidiplug member is turned'in saidstationary socket amemberiabout said I axis; and second contact means'fixed rfixed-to said 'socketrriernber and being 'spaced from said -axis in transverse direction substantially the same distance taszsaid first contact means andbei'ng located -in'said' path F ofssaidl'first contact means and spaced from said tfontact smeansiiin i said" first and second positions 'of -said pl'ug member and 'beingiin contact with-saidfirst'contac-t means I in: said" third position of i said -plug member to establish an; electrical contact with said first contactmeans.

4. F An electricalv outlet device comprising, in cornbi-nantion; ahollow socket member having a front plate formed with-an openingtherethrough and with af-le'ast one-slot aextendingrthrough said plate intransverse directionfrom z=.s'aid';opening-;i said front plate having a -rear *-face; a'pliag member *having a front" portion insertable through-said 'topening into said s'ocketm'ember in a 'predetermi'ned first Z position'. and turnable' therein in inserted position about -=aniaxis='-fromr said firstpo'sition to second "and -third 'pe i- 1'tions;::first contact means fixed to said' plugmefnb'e'rand comprising a lockingand: contact portion projecting' r-in transverse direction to said axis from said front portion of said 'plug member,isaid locking andcontact portion" having in a direction normal to saidaxisanioutline matching said slot in said front plate'so'tha't said locking and l contact portion are insertable through said slot in said i first portion of-said-plug membergsaid locking and' c'ontact portion having an-abutting -face sirbstantially 'h'oi'mal said axis abuttingagainstsaid inner *face of'said front '"plate insaid second and third positions of 1 said- "plug m'einber to":interlock-said plug memberwith said socket .zx'nemben' said -locking-- and= contact portion moving in a circular path when said plug member is turned in said stationary socket member about said axis; second contact means fixed to said socket member and being spaced from said axis in transverse direction substantially the same distance as said locking and contact portion of said first contact means and being located in said path of said lock- 10 ing' and contact'po'rtionand spaced from: said 'locliingf'a'nd jcontact-p'oftion 'in aid' first and secondpositionsr of stiid plug-member an c'onta ct'i'p ortion -in said' third position of said pl g-mem- "16 "about an axis from saidfi'rst'position to' second'a'nd'third positions; first contact-me'an'sfixed' to saidplug'menibcr and 'comprisinga locking and "contact portionprojecting in transverse direction to "said axis from "saidtr'ont 'p'or- 'tion' of said plugfirmber, "said" locking airdmontact 20 'fp'ortion having inadirectiofi normal tosaid axisian outline matchingsaid'slot"in said front plate so thatsaiddocking 5 Rand contact-portion are insertablethrouglr said slot insaid *first'po sition ofsaid plug member, saidlo'cki'ng' and contacflportion having an abutting face substantially normal to said axis abutting against 'saidfinnerface' of said front *plate' in said second and'third'positions'of-said plugm'emher to interlock said plug member With said socket member, saidlockin'g and-contactportion movingin a' circular "path'when said-plug member is 7 turned in said stationary socket member about "saidaxis; second "contact m'cans fixed to said socket member and beingspaced' ir'om said 'axis'in transverse direction substantially thesamedistan'ce "as saidlockingand-contact'portion of said'first contact meansandb'eing locatedinsaid path: offsaidloeking and contact portion and spaced froml'said locking and contact por'tionin said firstand second positions"ofsaid"plug member and bein in contact witlrsaid locking and contact porti'onin said third-position of s'aid"plug' member to 40' first retaining means extending from" said rearface of said fr'ont pl-ate and cooperating with'said abutting face'f or retaining said 1 plug member in" saidsecond position;" and second'- =retaining means on one of said contact means and cooperating with theother of'saidcontact"nieans"forfre- 'taining -said'plug member 'in said'thi'rd position.

' '6. -An electrical outlet device comprising; in combina- *tion, ahollow socket-member 'having a front plate 'form'ed With an "opening therethrough and with at leastio'nef slot extendingthrough said' plate in"transv'erse direction from saidopening, saidfront:plate"having a rear face; a,pl'i1g r'ner'nbefhaving 'a front" portion 'inse'rtable througlifsaid "openinginto said-socket member'in a predetermined Zfi'r'st position- 1 and "turnable thereinin' inserted position about arrarns" from said first position to second and third posi- 'tions';' 2 first contact 'means' fixed toksaid plugj memberjaiid -"comprising a 'locki'ng and contact portionjprojectingin transverse dir'ection to said axisfrom saidtfrontcpor'tion of said-plug member, said locking, and contaetportion having in;'adirectiorr normal itosaid axist'an outlinematchfi fing said slot i in said front "plate so that saidclocking-iand fcontactfpo'rtion are ins'ertable through said 1 slot in? said first; position of said plug member, said locking i and contact fportioril'iaving an. abuttingt face substantiallynormal ljto'said axis abutting.againstsaidinner face of-said' front fplatelin said secondand third :positions ;of' said-plug member to interlock saidiplug member with. said-socket memf'ber,'said'l'dcking"and contact portion moving-in a-circuiar patir"wheni said plug-member is :turned in said ;stationary""socket member about said axis; second contact means fixed to said socket member and being spaced from said axis in transverse direction substantially the same distance as said locking and contact portion of said first contact means and being located in said path of said locking and contact portion and spaced from said locking and contact portion in said first and eing in contact with said locking and 1 1 second positions of said locking and contactportion in said third positiontof said plug member to establish an 1 electrical contact with said first contact means; and an interrupter plate made of insulating material and being mounted in said socket member opposite said second contact means and extending in a direction tangential to said circular path, said interrupter plate being formed with an opening therethrough and being movable in said tangential direction between a first position where said opening is between said first and second contact means so said contact means may contact each other and a second position where said interrupter plate is located between said contact means to shield said contact means from each other said interrupter plate having engaging faces cooperating with said locking and contact portion of said first contact means during said turning of said plug member from said third to said second position thereof to move said contact plate in said tangential direction and in the same sense as said plug member; spring means engaging said interrupter plate from opposite sides and tending to keep said interrupter plate in said first position, one of said spring means being deformed during tion to said second position so as to move said interrupter plate to said second position thereof at the moment of contact disengagement during the turning movement of the plug member.

7. An electrical outlet device comprising, in combination, a hollow socket member having a front plate formed with an opening therethrough and with at least one slot extending through said plate in transverse direction from said opening, said front plate having a rear face; a plug member having a front portion insertable through said opening into said socket member in a predetermined first position and turnable therein in inserted position about an axis from said first position to second and third positions; firstcontact means fixed to said plug member and comprising a locking and contact portion projecting in transverse direction to said axis from said front portion of said plug member, said locking and contact portion having in a direction normal to said axis an outline matching said slot in said front plate so that said locking and contact .portion are insertable through said slot in said first path when said plug member is turned in said stationary socket member about said axis; second contact means fixed to said socket member and being spaced from said axis in transverse direction substantially the same distance as said locking and contact portion of said first contact means and being located in said path of said locking and contact portion and spaced from said locking and contact portion in said first and second positions of said plug member and being in contact with said locking and contact portion in said third position of said. plug member to establish an electrical contact with said first contact means; first retaining means extending from said rear face of said front plate and cooperating with said abutting face for retaining said plug member in said second position; second retaining means on one of said contact means and cooperating with the other of said contact means for retaining said plug member in said third position; and spring means mounted in said socket member, spaced from said front plate and opposite said opening through said front plate, said spring means ention, a hollow socket member having a front plate formed with an opening therethrough and with at least one slot extending through said plate in transverse direction from said opening, said front plate having a rear face; a plug member having a front portion insertable through said opening into said socket member in a predetermined first position and turnable therein in inserted position about an axis from said first position to second and third positions; first contact means fixed to said plug member and comprising a locking and contact portion projecting in transverse direction to said axis from said front portion of said plug member, said locking and contact portion having in a direction normal to said axis an outline matching said slot in said front plate so that said locking and contact portion are insertable through said slot in said first position of said plug member, said locking and contact portion having an abutting face substantially normal to said axis abutting against said inner face of said front plate in said second and third positions of said plug member to interlock said plug member with said socket member, said locking and contact portion moving in a circular path when said plug member is turned in said stationary socket member about said axis; second contact means fixed to said socket member and being spaced from said axis in transverse direction substantially the same distance as said locking and contact portion of said first contact means and being located in said path of said locking and contact portion and spaced from said locking and contact portion in said first and second positions of said plug member and being in contact with said locking and contact portion in said third position of said plug member to establish an electrical contact with said first contact means; first retaining means extending from said rear face of said front plate and cooperating with said abutting face for retaining said plug member in said second position; second retaining means on one of said contact means and cooperating with the other ofsaid contact means for retaining said plug member in said third position; third contact means centrally located in saidplug member, extending therethrough and being insulated from said first contact means; spring means mounted in said socket member, spaced from said front plate and opposite said opening through said front plate, said spring means made from conductive material and forming fourth contacting means and engaging said third contact means on said plug member in inserted position of'the latter to urge said abutting-face of said locking and contact portion against said rear face of said front plate of said socket member when said plug member is in said second, and third positions and to establish a contact between'said third and fourth contact means; and means for grounding said fourth contact'means.

References Cited in the file of this patent UNITED STATES PATENTS 978,841 Buckton Dec. 20, 1910 1,593,985 Nielsen July 27, 1926 1,615,726 Row Ian. 25, 1927 1,700,437 Hubbell Jan. 29, 1929 2,321,508 Olley et al. June 8, 1943 2,454,221 Seals Nov. 16, 1948 2,646,475 Goodrich et al. July 21, 1953

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