US2761113A - Electric plug-in receptacle having a plurality of outlets for attachment plugs - Google Patents

Description

Aug. 28, 1956 R 1, SPENCER ETAL 2,761,113

LECTRIC PLUG-IN RECEPTACLE HAVING A PLURALITY OF OUTLETS FOR ATTACHMENTS PLUGS Filed March 22, 1955 INVEN TORS: Eaberi' Z Jfiencer @harlas E Jnczi United States Patent ELECTRIC PLUG-1N RECEPTACLE HAVING A PLURAZIJITY OF OUTLETS FOR ATTACH- PLUGS Robert 1. Spencer and :Charles H. Jandt, Los Angeles, Calif.

Application March 22, 1955, Serial No. $95,952

3 Claims. ((31. 339-159) This invention relates generally to electrical connectiondevices and is concerned more particularly with a .tnultiple electric plug-in receptacle by which a plurality of the .electric cords of appliances, lamps, etc., may be :Connected :to a.-source of electricity.

Electric service outlets installed in walls are usually .provided with a pair of doublepronged electric sockets into which "the prongs or contact fingers of appliance cord plugs are insertable to connect the appliances or lamps to the source of electricity. Due to the large number of lamps and appliances commonly found in the home and the fact that several of these electrical products may be used simultaneously, it frequently occurs that the two electricsoekets may be insufiicient to meet the need. For this reason, it is the practice to employ a multiple socket attachment .or auxiliary receptacle which has a pair of main prongsreceivable in the contact openings or sockets p of the wall receptacle, the contact fingers or prongs of the multiple outlets of the receptacle attachment thus receiving electric current from the electric wiring. The .prongs of the appliance cord plugs, being frictionally held in the contact openings .of the auxiliary receptacle, serve to convey the electric-current to the. appliances.

Auxiliary multiple socket plug-in receptacles used for the purpose outlined above are widely used and take many forms. In general, such devices consistof molded plastic blocks -or hollow casings having a pair of main prongs at one side by which the auxiliary plugwin receptacle is electrically connected to the contacts of the wall receptacle. The pairs of contact openings, into which the appliance cord plugs are insertable, are invariably located at the :outer face .of theblock or casingor in slopingfaces .of the same, the plugged-in appliance cords thus projecting .from the plug-in receptacle .in a direction normal, or nearly normal, to the wallet theroom. Such plugging in of the. appliance.cords results ;in an unsightlytcondition .whichimpairs the appearance .oftheroom, theipoints .of connection -of the plugs being spaced "at a tconsiderable {distance from the wall due to the relatively large block like .nature .of the .plug-in receptacle and the appliance icords depending from the receptacle .in loops. As is well .known, the outwardly projecting and looping appliance icords create .a hazardous .cendition, .Lproviding obstacles .ovenwhichapersonmayitrip and fall. ilmaddition, since the appliance cords .project :at right-angles from the plug- ;in receptacle, that is, parallel to the main iprongs, the act ,of ,pulling a 'cord from .the receptacle .frequently results :in inadvertent displacement of the .entire assembly of receptacle and cards .from :the service-outlet .and .in some cases where the room is lighted ,by lamps :connected to .the receptacle, the light may be extinguished. This results in confusion and inconvenience since re-plugging of the receptacle block into the service outlet in the dark is not easily accomplished.

It is an object of ourjinvention to obviate the disadvantages and deficiencies of conventional plug-in receptacles referred to above by providing a multiple soc'ket'plug-in receptacle "in which the contact prong openings extend .in planes :at right-angles to plane .of the main plug-in prongs. By this provision, the appliance cords plugged .into the auxiliary receptacle project therefrom in a plane ,parallel to 'the wall of the room and the occurrence of unsightly and dangerous loops projecting outwardly into the room is effectively avoided. In addition, since the plugged .in appliance cords are removable from the receptacle by pulling them =.in.a plane normal to the main prongs, it follows that any tendency to accidentally dislodge the receptacle from the service outlet in the wall is eliminated. Preferably, the seriesof pronged outlets of the auxiliary receptacle are arranged at the bottom face of the receptacle sothatthe-appliance cords extend downwardly toward the floor, this feature making it possible to arrange the cords along the baseboard without the occurrence of loops or bendszintheicords.

Another object .of1the'inventioniis to provide a plug-in receptacle, of the character referred to, :which takes the form of a flat, rectangular plate of minimum thickness and of a length which is substantially equal to the width of the cover plate .of a service outlet so that when the receptacle is plugged .into the service outlet it appears to be an integral .part thereof. Preferably, the plate-like, plug-in receptacle is .of .a :height such that it covers only one=of the outletsof the .double socket service receptacle so that the other outlet remains accessible for use.

Another object of .the invention is to provide a plug-in receptacle which comprises .a pair of relatively thin, rec tangular plates molded from thermo-setting plastic material and :each having a horizontal, longitudinally extend ing, cored groove ,provided .with vertical branches extending .downwardly therefrom, to the bottom edge of the plate, the mating vertical portions together forming openings or-sockets for receiving the prongs of appliance cord end plugs. Disposed in rthe fork-shaped grooves of the plates are similarly shaped .bus bar having depending legs, vthe lower .ends of which provide contact fingers, .one within each prong socket, for engagement with the prongs of the .end plugs iinserted therein. Ac cording .to the invention, the bus barshave integral strips which project at right-angles thereto and outwardly through the back plate to serveas .the mainprongs of the plug-in receptacle. The ,two plates are joined together in .face-to-iface :relation by any suitable means, such as dowels-or screws,.or by cementing.

A .further :object of .the invention is to provide a plug- .in receptacle, .of theclass referred to, which issimple in construction and adapted for .economical mass production and one which is highly practical and safeto use.

IFurtherpbjects rof our invention will appear from the following description (and from the drawing which is intended for the purpose of illustration only, and in which:

Fig. liis a part+sectional, front elevational view of our improved plug-in electrical receptacle;

Fig. 2 isaplanzyiew of the same;

Figs. 3 and 4 are across-sectional views, taken respectively on lines .3-3 and '44 of Fig. l; and

i Fig. 5 is atrontfface view-of one of the plates forming one-half of'the :receptacle casing.

Referring to the drawingain detail, :the plug-in electrical receptacle includes a rectangular casing 10 which, as shown, -.comprisesa relatively thin, rectangular back plate 11 .and aisimilardrom plate 12. The :plates 11 and 12 are molded from :thermosetting plastic material and preferablykhave a width substantially equal to the width of .a conventional service outlet cover plate such as indi cated at 13. The heigh'bof 'the plates 11 and 12 is substan'tially equal *to one half the height of the cover plate 13. The plates 1-1 and 12 are assembled in face-to-face relation and their combined thickness is preferably equal to one-half inch, or less.

The back plate ill of the receptacle casing is provided in its front face with a cored horizontal groove or recess adjacent its upper edge portion. The plugin receptacle is herein shown, by way of example, as of the triple outlet type and in such a receptacle the back plate 11 is provided with six branch grooves 16 which project downwardly from the horizontal groove 15 in equally spaced relation. The lower ends of the branch grooves 16 provide sockets 17, the lower ends of which are reduced in width to provide narrow openings 13 extending to the lower edge of the plate. The back plate 11 is also provided with a threaded aperture 19 and a pair of rectangular holes 20 and 21.

The front plate 12 of the plugin receptacle casing llll has in its rearward face'a groove 15, 16', 18 similar to the groove 15, 16, 18 of the plate 11, the several grooves mating when the two plates are joined in abutting face-to-face relation.

The plug-in receptacle includes a brass contact element which has a horizontal bus strip or bar 26 adapted to fit snugly within the horizontal groove 15 of the back plate 11. The element 25 also has three legs 27 which are formed integrally with the bus bar 26 and extend downwardly therefrom to be positioned within alternate branch grooves 16. The lower end portions of the legs 27 are located within alternate sockets l7 and are twisted at 28 and formed to provide curved contact fingers 30. The contact element 25 has a flat strip 33 which projects rearwardly through the hole 20 to serve as 2. prong.

The front plate 12 is also provided with a contact element 25 of a shape similar to that of the element 25, having a horizontal bus bar 26, fitting in its groove 15 and depending legs 27' disposed in its branch grooves 16, the legs 27' having curved contact fingers 30' located within alternate sockets 17. The contact element 25 has a rearwardly extending prong 33'.

The rectangular plastic plates 11 and 12, with their contact elements 25 and 25' in place therein, are joined with their respective front and rearward faces in engagement, an insulator strip 35 being interposed therebetween. With the plates joined together, the prong 33 extends rearwardly through the hole 21 so that both prongs 33 and 33 project from the back of the plug-in receptacle. The plates 11 and 12 may be joined in a variety of ways such as by interengaging dowels and sockets, by cementing their engaging faces together, or by a screw 36 passing through a hole in the front plate 12 and screwed into the hole 19 of the back plate 11.

With the plates 11 and 12 thus joined, the contact fingers 38 and 30 of the respective contact elements 25 and 25' are disposed in alternate sockets 17, as clearly shown in Fig. 1. The contact fingers thus are arranged in three separate pairs 30, 30', each pair providing a receptacle or outlet, all having their openings at the bottom edge of the casing 10.

To apply the multiple outlet receptacle to use, it is simply placed against the cover plate 13 of a service outlet and'its prongs 33 and 33' are forced into a pair of prong openings 4%} thereof. In this manner, the plugin receptacle is mounted flat against the cover plate 13 by reason of the frictional engagement of its prongs 33,

'33 in the openings 40. The bus elements 25 and 25' thus are connected to the service outlet in a manner such that electric current passes to the several contact fingers 3t and 36]. When the plug-in receptacle is electrically joined to one of the sockets of the service outlet as shown in Fig. l, the other socket remains exposed and may be utilized in the usual manner, the plug-in receptacle covering only one-half of the cover plate 13. Preferably, the plug-in receptacle is so mounted that its sockets 17 are lowermost, as shown in Fig. 1.

To electrically connect a lamp, radio or appliance to the service outlet, it is only necessary to insert the prongs 45 of the end plug 46 of the double wire cord 47 into a pair of adjacent sockets 17 of the casing 10. By this procedure, the prongs 45 frictionally engage the contact fingers 30, 30' which, as explained above, are connected in parallel with the electrical circuit of the building. Appliance cords thus connected to the plug-in receptacle are adapted to project downwardly therefrom, parallel to the wall, and upon reaching the floor they may be bent to extend along the baseboard or floor in the required directions.

Connection of the appliance cords to the fiat plug-in receptacle provides a very satisfactory solution to the problems encountered when conventional plug-in blocks are employed for the purpose. The manner in which the cords are plugged into the receptacle results in a greatly improved appearance. In addition, the weight of the appliance cords is applied at a point close to the wall so that any tendency for the receptacle to pivot downwardly due to the weight of the cords is effectively minimized. This represents an important improvement over conventional plug-in receptacle blocks wherein the appliance cords are plugged in at outer faces of the block and thus create a cantilever force tending to pivot the block down- Wardly and disengage the prongs of the block from the contacts of the service outlet. It is also important to note that disconnection of an end plug 46 from the receptacle casing 10 is effected by simply pulling the end plug downwardly and that such applied force, at right-angles to the main prongs 33, 33', will not pull the receptacle from the service outlet. This is also an important improvement over conventional plug-in blocks where the cords are removed by pulling them outwardly in a direction parallel to the main prongs, such applied force frequently resulting in displacement of the plug-in block fro-m the service outlet.

In accordance with the provisions of the patent statutes, we have herein described the principle of the invention, together with the structure which We now consider to represent the best embodiment of the invention. We wish to have it understood, however, that various modifications might be made in the plug-in receptacle structure without departing from the spirit or scope of the invention, as defined in the appended claims.

We claim as our invention:

1. An electrical plug-in receptacle, comprising: a flat, rectangular casing of dielectric material having a plurality of plug-in sockets in an edge thereof; and a pair of identical contact elements within the casing, each element having a plurality of integral, coplanar, contact fingers, the fingers of the elements being located in alternate sockets, said contact elements having integral prongs projecting from a fiat face of said casing, normal to the plane of said longitudinal edge, said contact fingers in each pair of sockets having curved extremities extending in planes normal to the fingers and frictionally engageable with the prongs of an appliance cord end plug inserted into said sockets, normal to the plane of said edge.

2. An electrical plug-in receptacle, comprising: a flat, rectangular casing of dielectric material having a plurality of plug-in sockets in a longitudinal edge thereof; and a pair of identical contact elements Within the casing, each element having a plurality of coplanar contact fingers, the fingers of the elements having right-angularly twisted extremities located in alternate sockets, said contact elements having integral prongs projecting from a flat face of said casing, normal to the plane of said longitudinal edge, said contact fingers in each pair of sockets being frictionally engageable with the prongs of an appliance cord end plug inserted into said sockets, normal to the plane of said edge.

3. A plug-in receptacle as defined in claim 2 in which the casing has a groove provided with a first portion extending parallel to said longitudinal edge and a plurality of branch portions extending normal to said edge and providing said sockets, and in which each contact element has a bus bar portion disposed in a said first portion of a said groove, and a plurality of coplanar legs projecting normal to said bus bar portion and disposed References Cited in the file of this patent in alternate branch portions, said legs having right-ang1 1- UNITED STATES PATENTS lat-1y extendlng, curved, flexble contact fingers at them 2 44 367 A H 1 4 free ends disposed within alternate sockets, each pair of g M et "g adjacent sockets and the contact fingers therein consti- 5 z 53 22? Z 2 t l J I utmg a receptacle for a doub epronged electrlc plug 2,637793 Korecki H y 5 1953 2,702,893 Paulson Feb. 22, 1955

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