US 2720633 A
Description (OCR text may contain errors)
Oct. 11, 1955 o. E. WESTBERG 2,720,633
CLAMP FOR ELECTRICAL CONNECTORS Filed June 12, 1953 j I II I United States Patent CLAMP FOR ELECTRICAL CONNECTORS Oscar E. Westberg, Williston, N. Dak.
Application June 12, 1953, Serial No. 361,299
3 Claims. (Cl. 339-75) This invention relates to clamps for holding electrical plug-and-socket type connectors in assembled and electrically connective relationship.
Electrical extension cords are widely used in connecting lamps, appliances, shop equipment and other movable electrical equipment to electrical outlets. Connections between cords, as well as between cord and equipment, are commonly made by means of separable plug and socket members attached to the respective cord ends. The plug member provides a pair of electrically conductive prongs which slide into corresponding slots in the socket member, where they are frictionally held in place by, and make electrical contact with, springy conductive inserts therein. The two conductors of each of the two respective cords are attached respectively to the two prongs of the plug member and the two inserts of the socket member at points within insulating coverings forming the body portions of each of said plug and socket members.
It frequently happens that extension cords must be suspended from overhead appliances or outlets, moved about, pulled over and around obstructions, and generally subjected to stress during use. The frictional forces holding plug and socket connectors of such cords in connected relationship are insufficient to withstand any but the lightest of such stresses, with the result that the connection is easily broken. The plug and socket may be taped or wired together, but must then be laboriously untaped or cut apart before they can be separated. Various mechanical devices have been suggested for the purpose, but these have been of complicated structure involving multiple parts; or they have been unduly expensive, or difi'icult to apply or remove; or they have proven impractical for other reasons.
It is therefore an object of the present invention to provide a simple and economical but highly efiective clamp member which can be easily and quickly applied to and removed from a plug-and-socket connector; and which when applied thereto will remain firmly attached and will maintain the elements of the connector in operable relationship under all usual operating stresses.
The invention will now be described by reference to the accompanying drawing, in which Figures 1 and 2 illustrate in perspective two specific modifications of the invention as applied to plug-and-socket type connectors, and Figures 3 and 4 are plan views of the two clamps of Figures 1 and 2 respectviely.
The clamp of Figure 1 consists of the C-shaped spring member, the ends of the 0 being bifurcated, the two flattened fingers 11 of each of the bifurcated portions being open forwardly of the clamp and in the form of a generally U-shaped segment of a substantially spherical surface, so that they fit closely over the rounded ends 12, 13 of the socket member 14 and plug member 15 of the connector and around the central tubular extrusions 16, 17 through which the cords or cables 18, 19 are passed. The spherical configuration of the finger members results in a firm grip being maintained by the or punching from a wide bar or sheet.
clamp 10 on the rounded ends of the connector, under the tension of the expanded C-shaped spring member. The spring member may be made of any desired thickness and width of stock and of any desired material, spring steel or spring bronze being highly acceptable. The fingers 11 in particular, or the entire clamp if desired, may be coated with a protective and decorative finish which may also be chosen to provide electrical insulating qualities.
Alternatively, the U-shaped end sections and the C- shaped spring section may be made separately and of the same or different materials. For example, a metal spring member may be fitted with plastic or other non-metallic finger-forming end members, held in place by rivets or other suitable means.
The modification illustrated in Figure 2 is designed to be applied to the cords or cables rather than directly to the plug and socket. The fingers 21 formed at the bifurcated ends of the C-shaped spring of clamp 20 form a claw member at each end of the C-shape springs, said claws fitting around the wires 28, 29 attached respectively to the socket member 24 and the plug member 25, and pressing firmly against the tubular extensions 26 and 27 thereof to hold the plug and socket members together in electrically connective relationship.
Clamps having rounded fingers 11 as shown in Figures 1 and 3 at one end of the C-shaped spring member and claw-shaped fingers 21 as shown in Figures 2 and 4 at the other end are applicable to certain types of connectors, and various other modifications of the invention will occur to those skilled in the art upon consideration of the disclosures here provided.
One advantage of the form of clamp illustrated in Figure 2 is that it is adapted to a wide variety of connectors, including those having end portions of irregular shape, since the finger members 21 attach to the electrical cord rather than to the connector itself; whereas the finger members 11 of clamp 10 of Figure 1 are designed specifically for use with connectors having rounded end areas. The clamp of Figure 2 may be formed from a segment of straight bar stock of uniform width, whereas that of Figure 1 is more easily produced by cutting However the clamp of Figure 1 is somewhat more readily formed than that of Figure 2 by simple punch-press methods; it may be made of a uniform width strip of stock by merely expanding the C-shaped clamp portion to the same width as the area covered by the fingers 11 or by folding a wider strip to form the narrower C-shaped spring section shown; and since most electrical extension cords are presently fitted with plug and socket members having uniformly shaped rounded ends, it is capable of adequately wide-spread application.
Having now described and illustrated specific embodiments of the invention, but without limiting the invention thereto, what is claimed is as follows:
1. A clamp for maintaining plug and socket members of an electrical connector in electrically connective relationship as herein described, said clamp comprising a single elongated fiat strip of spring metal permanently formed into a C-shaped clamp having each of the ends of the C bifurcated to form fingers lying on opposite sides of the central axis of an inserted connector and said fingers being shaped to remain firmly in place on said connector and to fit against the respective ends of said connector under the spring tension afiorded by the expanded C-shaped spring member.
2. A clamp for maintaining plug and socket members of an electrical connector in electrically connective relationship as herein described, said clamp comprising a single elongated spring member permanently formed into a C-shaped clamp having each of the ends of the C bi- 3 g furcated to form fingers lying on opposite sides of the central axis of an inserted connector and said'fingersbeing shaped to remain firmly-in place on said connector and to fit against the respective ends of said connector under the spring tension afforded by the expanded C- shaped spring member, the fingers of 'at least one bi-' furcated end of said C-shaped spring member being in the form of a U-shaped segment of a substantially spherical surface.
'3. A clamp for maintaining plug and socket members of an electrical connector in electrically connective relationship as herein described, said clamp comprising a onepiece C-shaped spring member having each of the ends of the C bifurcated to form fingers lying on opposite sides of the central axis of an inserted connector and said fingers being shaped to remain firmly in place on said connector and to fit against the respective ends of said connector under the spring tension afforded by the expanded C-shaped spring member, the fingers of at least one bifurcated end of the C-shaped spring member being in the form of an open-ended rounded claw capable of fitting tightly 0n the electrical cord attached to the plug and socket members of the inserted connector.
' References Cited in the file of this patent UNITED STATES PATENTS 1,717,877 DOlier a June 18 ,1929 1,989,823 Raabe Feb. 5, 1935 2,461,427 Kneebone Feb. 8, 1949