US2553371A - Electric plug - Google Patents

Description

May15,1951 w. HUPPERT 2,553,371

ELECTRIC PLUG Filed Jan. 2, 1948 Tl :iig ,i (//7/// l /0 f @j /f/z/A/I/ Qa/amar I I mm Patented May 15, 1951 ELECTRIC PLUG William Huppert, New York, N. Y.; Ruth E. W.

Huppert executrix of said William Huppert, de,-

ceased Application January 2, 1948, Serial No. 205

1 Claim. i

This invention relates to an electric plug, particularly of the type known as a quick detachable plug for making electrical contact with an outlet, base, receptacle and the like.

The approved practice in detaching such a plug is to graspl the body instead of the wires. However, in many, if not in most, instances it is customary to detach the plug by pulling on the wires leading from the plug. Repeated detachment in'this manner tends to break the wires, usually at the points where they are connected to the blades, or otherwise to weaken, and ultimately destroy, the electrical contactl of the wires and the blades.

One of the objects of the present invention is to provide a plug construction that will overcome that objection, and will permit of repeatedly detaching the plug by pulling on the wires without resulting in loosening or breaking their contact with the blades.

' Another object of the invention is to provide plug construction having a strain relief so that the harder the wires are pulled the tighter their insulation covering will be gripped.

A further object of the invention is to provide a plug construction that permits of quick and easy assembly of the blades and body.

A still further object of the invention is to provide a plug construction that is simple and economical to manufacture.

Other objects and advantages of the invention will appear from the following specication, reference being had to the accompanying drawings forming a part thereof, in which:

Fig. l is a side View of the plug; v

Fig. 2 is a vertical longitudinal medial section of the plug, the wires being shown in full lines;

Fig. 3 is a vertical transverse section on the line 3 3 of Fig. 2 with the blade partly broken away;

Fig. 4 is a similar section with the blade and Wires removed;

Fig. 5 is a vertical transverse section on the line 5--5 of Fig. 2;

Fig. 6 is a bottom plan view of the plug;

Fig. 7 is a fragmentary horizontal section on the line 'I-'I of Fig. 2;

Fig. 8 is a perspective view of one of the blades before attachment to the plug;

Fig. 9 is a sectional view similar to Fig. '7 but with the blade and wires omitted; and,

Fig. 10 is a section on the line Iii- IIJ of Fig. 2, also with the blade and wires omitted.

In general the plug comprises a hollow onepiece molded body It of insulating plastic maat a right angle to the first.

terial or other suitable substance; a pair of blades II-I I each' having anchoring means at one end consisting of two prongs I2-I2 that diverge in V-form and that have relatively sharp curved tips I3, which blades are anchored to the body in'substantially the manner described in my copending application Serial No. 595,451 which matured into Patent No. 2,495,104 on January 17, 1950; and, two insulation covered wires MLM that are preferably joined together and the ends I5 of which are bared of insulation to make electrical contact with the blades.

The interior cavity of the hollow body Iii is substantially rectangular in shape, formed with integral vertical bosses" I6 at its four corners and with other integral vertical bosses Il spaced from ther former. The spaces between the boss pairs IG--I'I provide sockets in which the blades Il are received. The length and breadth of the sockets, measured horizontally, are a little larger than the corresponding width and thicknessof a blade to provide a slight clearance between the blade and socket so that in assembling the parts the blades may be freely inserted into the sockets.

Walls or webs I8-I are formed integral with and connect each pair of bosses Il along their inner surface, said webs being thinner than the bosses, as seen in Figs. 7 and 9. Each web has a vertical slot I9 open at the bottom, as best seen in Fig. 4, which slot is Wider at its open bottom than at its upper portion. The opening into the slot is slightly greater in width than the diameter of an insulated Wire I4 so that the wire may be easily inserted into the slot. However, since the width of the upper portion of the slot is less than the diameter of the wire, the insulation covering of the wire will be constricted by the slot as the wire is pulled up into it, and the edges 20 of the narrow portion of the slot will tightly grip the insulation, thus providing a strain relief for the wire. To assist in gripping the insulation the edges of the slot are preferably bevelled. A hole 2| extends vertically through the central axis of the body Iii for passage of the wires into the interior cavity of the plug.

On reference to Fig. 7 it will be seen that the spacing between the opposed faces of blade II and wall I8 is slightly less than the normal thickness of a covered wire Id. Accordingly, the insulation covered portion of the wire that is conned in that space will be distorted from its normal shape, that is to say, it will be compressed in one direction and elongated in the direction The distortion of the insulation wedges the wire tightly in this space and aiTords an additional strain relief.

It will be apparent that the strain reliefs afforded by this construction will eiectually prevent breaking of electrical contact between the blades and the wires on detaching the plug by pulling on the wires instead of gripping the body.

The bared ends i5 of the wires are bent about the anchored ends of the blades Il and are tightly gripped between said ends andthe op-rl posed portions 22 of the body cavity, as seen in Fig. 2.

In assembly, the blades are inserted in contact with the wires into the 4blade-receiving sockets. The prongs I2, which normally form a' V with each other, as shown in Fig. 8, are then spread to assume the substantially horizontalY position shown in Fig. 5. spreading is eiected only after free insertion of the blades into their sockets. In the spreading movement, the relatively slender curved tips I3 of the prongs will bite intok the material 'of the body and on meeting the resistance thereof will bend or curl in the direction of their curvature without exerting any undue pressure'v on the material and will thus form recesses 23 in which the spread prongs of the blades are held or an'- chored.` TheV provision of prongs that operate in this manner constitutes anl improvement of the anchoring devices of my copending application, hereinbefore referred to, in that th-e easily bendable curved tips of the prongs limit the pressure that the prongs exert on the material on being spread, and thereby practically eliminate any danger of breakage of the body in securing the blades thereto.

Various modifications in they details of the construction herein described and illustratedY in the accompanying drawings may be made within the spirit and scope of the invention.

I claim:

An electric plug comprising a hollow body hav- As hereinbefore noted, the' lsage to afford a strain relief, the ends of the wires passing into said sockets beyond said passagesA being bared of their insulation covering, anda blade having an end portion in each socket, each blade' having a pair of prongs diverging outwardly from said one end to an extent greater than the wid-thor the blade with the tips of said prongs engaged in the side walls of the socket, the-bared end of each wire being bent about said lower end of the blade to make electrical contact therewith, the portion of said bared end that passes under the prongs being 'tightly' wedged between said prongs and the closed end of the socket in which the blade is secured.

WILLIAM I-IUPPEPJ11V 1 REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS ,y

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