US2771590A - Interlocking electrical plug assembly - Google Patents

Description

Nov. 20, 1956 B. F. NAUSLAR INTERLOCKING ELECTRICAL PLUG ASSEMBLY Filed May 15, 1953 INVENTOR. BENJAMIN F. NAUSLAR mamm AGENT$ FOR APPLICANT INTERLOCKING ELECTRHiAL PLUG ASSEMBLY Benjamin F. Nauslar, San Diego, Calif.

Application May 15, 1953, Serial No. 355,299

1 Claim. (Cl. 339--168) This application is a continuation-in-part of my copending application Serial No. 85,075, filed April 2, 1949, now Patent No. 2,643,364 and relates particularly to an interlocking electrical plug assembly.

The primary object of this invention is to provide an interlocking electrical plug assembly, the male and fe' male portions of which are interchangeably useable with conventional plug of the same size.

Another object of this invention is to provide an electrical plug assembly in which the electrical contacts are integral with the plug locking means, thus simplifying and decreasing the cost of construction of these elements.

Another object of this invention is to provide an interlocking electrical plug assembly, the structure of which may be applied to conventional plugs with the. minimum of modification.

Another object of this invention is to provide an interlocking electrical plug assembly which is adapted for fabrication from many different materials, so that the choice of material can be according to the dictates of availability and price considerations, the exact sizes and proportions being matters easily determined to suit particular conditions and needs.

Another object of this invention is to provide an interlocking electrical plug assembly which is inexpensive and practicable to manufacture.

Finally, it is an object to provide an interlocking electrical plug assembly of the aforementioned character which is simple, safe and convenient to operate, and which will give generally efficient and durable service.

With these and other objects definitely in view, this invention consists in the novel construction, combination and arrangement of elements and portions, as will be hereinafter fully described in the specification, particularly pointed out in the claim, and illustrated in the drawing which forms a material part of this disclosure and wherein similar characters of reference indicate similar or identical elements and portions throughout the specification and throughout the views of the drawing, and in which:

Fig. l is a perspective view, partially cut away, of the interlocked male and female plug portions.

Fig. 2 is a side elevation view of the female plug portion.

Fig. 3 is a sectional view taken on the line 33 of Fig. 2.

Fig. 4 is a sectional view taken on the line 4-4 of Fig. 3.

Fig. 5 is a perspective view of the male plug portion.

Fig. 6 is a fragmentary sectional view of a wall type electrical outlet showing the female plug portion as adapted for use in a wall type outlet.

Fig. 7 is a perspective view of the male plug portion used with the wall type outlet of Fig. 6.

Referring now to the drawing, the device comprises, briefly, a male plug portion 10 having a pair of contact prongs 12 and 14, and a female plug portion 16 having therein a pair of resilient contacts 18 and 20.

nited States atent 2 a The male plug 10 comprises a frame 21 of conventional construction, but the prongs 12 and 14 are provided at their free ends with projections or lips 22 and 24 respectively, the lip 22 being vertically opposed to the lip 24 as shown in Fig. 5. The prongs 12 and14 are, of course,

electrically connected to a two-wire conductor cable 26..

The female plug 16 comprises a frame 28 of substantially conventional construction having a pair of slotted. openings 3i) through which the prongs of the maleplug are inserted. Within the frame 28 and formed integrally therewith are a pair of ledges 32 disposed laterally of.

the slotted openings 30. r

The contacts 18 and 20 are inserted in the arcuate cavities 34 between the ledges 32 and the inner wall of the frame 28, being retained therein and substantially supported by means of insulation plates 36 and. 38 respectively.

The contact 18 is positioned toward. one side of the of substantially conventional design, wlhich enablesvtheplug to be screwed into a standard electrical socket. The

contact 20 is folded over the end of the insulation plate.

3%, as indicated at 48, and is in electricalcontact with the screwed cap 46 when the female plug is assembled. r

The contact 18 is extended outwardly throughthe end of the screwed cap 46 and through the insulating disc 50.

attached thereto, a suitable aperture being. provided in the screwed cap to prevent an electrical connection with said contact. The protruding end of the contact18 is bent as indicated at 52 to rest on the insulating disc 50, and isfastened by means of a screw 54 which isscrewed into the central pillar 42. This screw 54 holds the insulating disc 50 and the cap 4-6 to the'framejand conr pletes the assembly of the female plug. 1 i

It will be seen that when the male plug 10 is inserted into the female plug 16, the prongs 12 and 14 will strike the contacts 18 and 20. As the prongs are advanced into the female plug, the lips 22 and 24 on said prongs will pass the ends of the ledges 32. At this point, the opposed resilient loops 4t) and 44 pressing against the opposite sides of said prongs will bias the male plug to rotate a few degrees relative to the female plug, about an axis common to both plugs, so that the lips 22 and 24 will be forced over the ledges 32. In this position, the male plug cannot be removed by a direct axial pull, but must be rotated slightly against the pressure of the resilient loops 49 and 44, in order to disengage the lips 22 and 24 from the ledges 32.

The loops 4i) and 44 also being the electrical contacts of the female plug 16, a good electrical connection is made with the male plug 10 while the prongs are locked in position.

It should be noted that the male plug 10 as shown in Fig. 1 has the lips 22 and 24 disposed so that the plug must be rotated in a clockwise direction in order to unlock the prongs. This clockwise rotation ensures that the female plug 16 will not be unscrewed from its socket during removal :of the male plug, most such femal plugs having conventional clockwise threads.

A slightly modified form of the invention is shown in Fig. 6 in which the structure is applied to a wall type electrical outlet. These outlets normally comprise a pair of female plugs, one of which has been illustrated. The female plug 56 comprises a frame 58 having a pair of slotted openings 60 through which the prongs of the male plug are inserted. The frame 58 is fastened to a mounting plate 62 which is attached to a conventional outlet box 64.

Within the frame 58 are a pair of ledges 66 similar in character and arrangement to the ledges 32 previously described. The contacts 68 are located behind the ledges 66 and are provided with terminals 70 protruding through the frame 58, to enable the electrical connections to be made. The contacts 68 have resilient loops 72 and are arranged in opposed positions in alignment with the slotted openings 60 in a manner similar to that previously described.

The male plug 74 comprises a frame 17 in which are fitted a pair of prongs 76 and 78, electrically connected to a two-wire conductor cable 26. The prongs 76 and 78 are provided at their free ends with projections or lips 80 and 82 respectively, the lip 80 being opposed to the lip 82, or extending in the opposite direction, as shown in Fig. 7. It should be noted that the prongs 76 and 78 are arranged so that counter-clockwise rotation is necessary in order to remove the male plug 74 from the female plug 56, this being the opposite to the rotation required to unlock the female plug 16. This counter-clockwise rotation is more suited for use with wall type outlets wherein no provision against unscrewing is required, in contradistiction to the case of the screwed type female plug shown in Figs. 1 to 4. The counter-clockwise rotation is consistent with the natural tendency when unscrewing or removing a plug or similar article and is therefore preferable when no provision against loosening is required.

The instant invention offers distinct advantages over conventional plugs by preventing accidental removal of the male plug due to a pull on the conductor 26. As an example, when. using an electric iron, the electrical cord is often extended to its full length, with the result that the male plug may be disconnected. The plug described herein prevents such an occurrence by locking the male plug firmly in place until removed intentionally.

The operation of this invention will be clearly comprehended from a consideration of the foregoing description of the mechanical details thereof, taken in connection with the drawing and the above recited objects.

It will be obvious that all said objects are amply achieved by this invention.

Further description would appear to be unnecessary.

It is understood that minor variation from the form of the invention disclosed herein may be made without departure from the spirit and scope of the invention, and that the specification and drawing are to be considered as merely illustrative rather than limiting.

I claim:

An interlocking electrical plug assembly including a female plug and a male plug having a common axis, said female plug comprising a frame having a central pillar, a pair of slotted openings in said frame spaced on opposite sides of said pillar, ledges within said frame disposed laterally of said openings and defining arcuate cavities with the walls of said frame, a pair of looped spring contacts disposed on opposite sides of said pillar and positioned in said cavities, the loops thereof being opposed to each other and aligned with said openings, insulated plates supporting said spring contacts and holding them in said cavities, a screwed electrically conductive cap secured to said frame and having a central. terminal insulated from the cap, one of said spring contacts being connected to said cap and the other of said spring contacts being connected to said terminal, said male plug comprising a frame having a pair of prongs spaced to align with said openings, said prongs each having a projecting lip, said lips being on opposite sides of said prongs, said spring contacts engaging said prongs on opposite sides thereof and urging said prongs together with said male plug frame to rotate slightly in one direction about said axis relative to said female plug and said lips engaging said ledges when said male plug is rotated slightly in said direction after insertion into the female plug.

References Cited in the file of this patent UNITED STATES PATENTS 1,376,068 Benjamin Apr. 26, 1921 1,753,064 Nonneman Apr. 1, 1930 2,026,755 Stem Jan. 7, 1936 2,149,550 Richards et a1. Mar. 7, 1939 2,220,810 Bright Nov. 5, 1940 2,643,364 Nauslar June 23, 1953

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