US3328748A - Dead-front connector cap or cord connector with integrally molded cord grip - Google Patents

Description

P.'H. WINTER 3,

DEADFRONT CONNECTOR CAP OR CORD CONNECTOR WITH INTEGRALLY MOLDED CORDGRIP n v 4 Sheets-Sheet 1 June 27, 1967 Filed July 20, 1964 iNVENTOR PAUL I-I. WINTER R 7 1 WW ATTORNEYS June 27, 1967 P. H. WINTER 3,328,748

DEAD-FRONT CONNECTOR CAP OR CORD CONNECTOR WITH INTEGRALL-Y MOLDED CORD GRIP Filed July 20, 1964 4 Sheets-Sheet 2 INVENTOR PAUL H, WINTER ATTORNEYS 5Y5. E fg 221 m z June 27, 1967 P. H. WINTER 3,328,748

, DEAD-FRONT CONNECTOR CAP OR CORD CONNECTOR WITH INTEGRALLY MOLDED com) GRIP Filed July 20, 1964 4 Sheets-Sheet 4 FIG. 15

I II VI 11 5 F/IQ 9,

uw/vrofi PAUL H. WINTER MW Arr RNEYS United States Patent GRIP Paul H. Winter, Syracuse, N.Y., assignor to Pass & Seymour, Inc., Syracuse, N.Y., a corporation of New York Filed July 20, 1964, Ser. No. 383,617 2 Claims. (Cl. 339107) This invention relates to connector caps of the types called attachment plugs or cord connectors, and more particularly to such caps having a dead front to protect and insulate the cord terminals and eliminate the chances of short circuits and shocks. The invention features a cord or cable grip molded integrally with the insulating material of the cap back plate.

It is a general object of the present invention to provide a novel connector cap having a dead front derived from a two-piece body having a contact and prongcarrying bottom body, and a cover or back plate providing an integral cord or cable grip.

More particularly, it is an object of the present inven tion to provide a connector cap having a two-part body of molded insulation, the bottom being cup-like and supporting either housed cord connector contacts or attachment prongs which extend through holes in the bottom of the cup, each contact or prong having a terminal plate seated in the cup to receive a conductor of a cord, the top body which is the cover or back plate at least partially nesting in the bottom, being attached thereto and having formed integrally therewith a cord or cable grip arranged to clamp the conductors extending through the back plate to relieve strain on the terminals, etc.

Another object of the invention consists in providing the cover or back plate which is perforated for conductor cord passage, with an integral cord-grip device comprising a pair of arcuate clamp members each having lateral wings through which screws are passed 'to pull the clamp members tightly together against a cord extending through the passage, each clamp member and its wings being spaced above the outer surface of the cover and integrated therewith by flexible connecting members.

Still another object of the invention consists in forming the combined back plate and cord grip by molding from a plastic having both rigidity and limited flexibility whereby changes in thickness of sections will provide the various requirements for proper strength and mobility. In one embodiment of the invention each terminal plate has an upstanding strut positioned to be engaged by the cover or back plate to hold the prong terminal plate securely in the body of the cap.

'Other and further objects and features of the invention will be-more apparent to those skilled in the art upon a consideration of the following specification and ofthe accompanying drawings wherein are disclosed several exemplaryembodiments of the invention, with the understanding that such changes and modifications may be made therein as fall within the scope of the appended claims without departing from the spirit of the invention.

In said drawings:

FIGURE 1 is a side elevation of a dead-front connector ca with integrally molded cord grip constructed in accordance with one embodiment of the present invention and illustrating a conductor cord secured to a grounding-prong type of cap; I I V 7 FIGURE 2 is a view similar to FIGURE 1 but displaced by anangle of 90 degrees from that showing;

FIGURE 3 is a top plan viewthereof in the absence of a cord; 7 i H v FIGURE 4 is a partial central vertical section on an "ice enlarged scale taken on line 44 of FIGURE 3 showing one of the main blades and its terminal plate in elevation;

FIGURE 5 is a perspective view of one of the main blade units;

FIGURE 6 is a fragmentary sectional view similar to FIGURE 4 but taken at right angles thereto and of a second embodiment;

FIGURE 7 is a perspective view, similar to FIGURE 5, of a contact and terminal unit for the cord connector of FIGURE 6;

FIGURE 8 is a similar perspective view of an attachment plug contact blade and terminal unit which may be substituted for the corresponding unit shown in FIGURE 4 without requiring position maintaining by the cover or back plate;

FIGURE 9 is a side elevation of a slightly modified dead-front connector cap with integrally molded cord FIGURE 10 is a view similar to FIGURE 9 but displaced by an angle of degrees from that showing;

FIGURE 11 is a top plan view of the device of FIG- URE 9;

FIGURE 12 is a bottom plan view of the top body portion of the device of FIGURE 9;

FIGURE 13 is a cross-sectional view of the top body portion taken along line 1313 of FIGURE 11;

FIGURE 14 is a top plan view of the bottom body portion with the cover disc in place and partly broken away;

FIGURE 15 is a cross-sectional view taken along line 1515 of FIGURE 14;

FIGURE 16 is an isometric view of a contact and terminal unit for use in the embodiment of FIGURE 9;

FIGURE 17 is a contact and terminal unit for use in the female embodiment of FIGURE 9;

FIGURE 18 is a vertical cross-sectional view illustrating the bottom body adapted to be provided with the contact of FIGURE 17;

FIGURE 19 is a cross-sectional view of the device of FIGURE 9 illustrating the manner in which the contact of FIGURE 16 is mounted therein and the top and bottom bodies are secured together; and

FIGURE 20is a cross-sectional view similar to FIG- URE 19 illustrating the mounting of the contact of FIG- URE 17 in the bottom body and the manner in which the top and bottom bodies are secured together.

Connector caps, often referred to as attachment plugs, and cOrd connectors, have been manufactured in many styles, shapes and materials, but those designed for relatively heavy-duty in combination with substantial-sized conductor cords or cables (rather than the more or less inferior integral parts of small portable electrical appliance cords provided with toasters, household equipment and the like) are normally fitted with substantial terminals for the attachment of the conductors of an electric cord or cable. In most instances these terminals constitute screws or the like, and are more or less exposed on the forward face of the cap which is customarily made of one piece of insulation hollow on the forward face, from which the blades project, and there house the terminals. These terminals and the bared sections of conductors are sometimes covered with a sheet of vulcanized fiber, but since the attachment is only by a friction fit of slots therein over the prongs of blades of the plug it is readily lost, and as a matter of fact, is oftentimes not reassembled by the person who wires the cap. Caps wired with stranded conductors, in particular, are subject to short circuiting after some usage because all of the strands do not necessarily remain firmly beneath the clamping screws. In any event, the conductors may become disarranged and short circuits occur, which are dangerous from a fire standpoint. Moreover, it is sometimes difficult to provide a rigid attachment for blade-s and prongs in this type of cap at a reasonable cost. The present invention, therefore, proposes to make the caps and connectors in two pieces, secured together by appropriate fastening means, one comprising a forward or bottom body section through slots in which the blades and prongs extend with a frictional fit. These blades have integral terminal plates, receiving attaching screws which are housed in a cup-like hollow in the rear of the bottom body and are then covered by a back or cover plate which has an alignment portion nesting in the cup of the body. This back plate can be made of a material having sufiicient rigidity and yet flexibility so that there may be formed integrally with it an insulating cable clamp which serves to take the strain from the conductors and their attachment to the plug blades when strain is put on the cable for one reason or another. Among these reasons is the fact that so often careless persons withdraw a plug from the receptacle or the like by a yank on the cord, which, in the absence of a cable clamp or grip transfers the stress to the conductors and the terminal screws.

By making the cable clamp or insulating parts, additional danger of possible short circuiting is obviated. The usual cable clamps are made of metal and the sections thereof tightly drawn together by screws so that eventually the cover of the cable can be chafed and the conductors short-circuited by the metal clamp elements. All of this is obviated by the present arrangement, and in addition, no loose parts which can be lost are used.

Referring now to the drawings for a better understanding of the invention, and first to FIGURES 1 to 5, inclusive, there is shown at 9 a dead-front connector cap with cable grip in accordance with the first embodiment of the present invention. It includes at 10 the bottom body portion of suitable insulation and which is preferably of circular or disc-like configuration, having a fiat bottom 11 and a circular side wall 12. This may be molded as shown and has adequate mechanical strength as well as insulating characteristics for its intended use.

The plug shown, by way of illustration, is of conventional style having a pair of parallel blades 14 and a longer grounding prong 15 of generally U-shaped crosssection, as is now conventional, but the arrangement and number of the blades and prongs can be varied to suit conditions and their style and number form no part of the present invention.

One of the plug blades 14 is shown in its complete form in FIGURE 5 where it will be seen that in addition to the elongated straight, flat, blade portion it has at right angles thereto a flat terminal section 17 which is perforated at 18 and threaded to receive a terminal screw 19 as seen in FIGURE 4. Such a blade unit is mounted in the bottom body 10 by passing the elongated blade 14 through an axially disposed slot 20 in the "bottom wall thereof and permitting the terminal plate 17 to rest on the bottom 22 of an individual close-fitting recess in the floor of the main depression in the rear of body 10. An extension 24 of each such individual recess is provided to give adequate clearance for the shank of each terminal screw 19, beneath the head 25 of which the conductors are twisted and clamped in the usual manner.

Referring to FIGURE 5 it will be seen that a lug or strut 26 is turned upwardly at right angles to the terminal plate and parallel to the axis of the blade 14 and closely adjacent thereto.

To cover, mechanically protect and electrically insulate the terminals and the bare portions of the conductors where the insulation has been removed for making connections by clamping beneath the screw heads, a back plate or cover 28 is provided preferably of the same diameter or other outer configuration as the portion 10, but substantially thinner axially, as seen in FIGURES l and 2. For reasons which will appear later this portion is preferably molded from nylon plastic, has a projection, with a flat forward face 29 reduced slightly in diameter to enter a short distance into the recess in the bottom body. A peripheral rabbet provides an area 30 which rests on the top narrow edge of the bottom body 10 as clearly seen in FIGURE 4. This arrangement holds the two parts against lateral movement and secures proper alignment for the fastening screws 32, FIGURES 1 and 3, the heads of which are countersunk in the part 28 as seen in dotted lines in FIGURE 1 and the shanks of which pass through close-fitting openings in the bottom body and are received in countersunk metal insets 34 which are noncircular and internally threaded to receive the threads of the screws to hold the parts rigidly assembled.

Each of the terminal plates for the several blades and prongs may be fitted with one of the struts 26 which is of such a height that it is tightly engaged by the underface 29 on the back plate, as clearly seen in FIG- URE 4, to press the terminal plate against the base 22 of its recess in the bottom body and thereby hold it rigidly in position. The blades and prongs are pressed into close-fitting openings through the bottom body as earlier mentioned, but to insure against their sliding inwardly when inserted into a receptacle, engagement with the back plate, just discussed, is relied on and assures a tight rigid mounting at all times even after major strenuous use.

To provide a cable clamp for holding the conductor cord or the like, rigidly and to relieve the terminals and individual conductors of strain, it is preferred to form it integral with the back plate 28, and this is done by molding. Nylon is ideal for the purpose because of its limited flexibility in relatively thin sections. FIGURE 4 shows the cord central opening 35, adjacent which are molded .the integral, flexible, extensions 36 projecting upwardly as continuations of the walls of opening 35, which, however, are of less than degrees in extent. A substantial distance above the top surface of cover 28, these extensions have relatively flat upper ends or tops 37. Each is substantially thickened in a radial direction a distance downwardly from the top to provide added rigidity over the flexibility afforded by the thinness at 36. There are thus provided two wings or curved clamp members 40 which can be drawn toward each other to engage the insulating cover of the cable or conductor cord and clamp the same as is clearly illustrated in FIGURE 3 as well as in FIGURES 1 and 2.

To provide clamping facilities, each of the clamp members 40' is fitted with -a pair of wings 41, each extending laterally from one of its side edges, as seen on the right in FIGURE 3, and at 42 on the left. These are so arranged that corresponding wings 41 and 42 are parallel to and confront each other to receive a clamping or tightening screw 43 which passes through an aperture in wing 41 closely receiving the shank thereof. Each screw has a hemispherical head 44 thereon engaging the outer face of wing 41. The wings 42, however, are treated dif ferently for their apertures are arranged to accommodate hollow tubes 46 internally threaded to be engaged by the threads on the screws. Each of these tubes is integral with a square head 47, best seen in FIGURE 2, which is received in a countersunk opening of the same configuration in the outer face of wing 42 to hold it against rotation. The opposite end of the relatively thin threaded sleeve is spun over as seen at 50 in FIGURES 1 and 3 to hold this combination tube and nut in position and insure against its being lost. Since the screws are sufiiciently long to permit the parts 40 to be spaced at least as wide as the walls of the bore 35, the ends of the screws can be upset to prevent them from being withdrawn and lost.

The relative thickness of the parts 40 and their lateral wings 41 and 42 is such as to give them sufiicient rigidity in spite of the limited flexible nature of the nylon plastic, which permits bending so that the parts 40 may be drawn toward each other to accommodate a cable or smaller diameter than the aperture in the cap. If it is considered necessary, circumferential ridges or grooves,

not shown, may be formed on the inner faces of the parts 40 to insure better grip on the cable sheath but in most cases will not be necessary since such sheaths are of rubber or plastic and the parts 40 will be suitably embedded therein when the screws are tightened.

This integral cable clamp is simple to manufacture, requires no assembly and is equally as effective as a multipart metal one without the short circuiting possibilities of the latter.

In the second embodiment of the invention, illustrated in FIGURES 6 to 8, the contact units are secured in the bottom body part independently of any engagement by or assistance from the back plate. This construction makes it feasible to form the back plate, and its integral cord grip, of a more universal type suitable for attachment plugs and cord connectors having various numbers and arrangements of blades, contacts and/0r grounding prongs.

Referring now to FIGURES 6 and 7 the assembly of body insulating parts includes the main or bottom part 60 corresponding generally to the cup of the first embodiment and a cover and cord grip unit 28 identical to that bearing the same number in FIGURE 4 and similarly interfitted and secured together as seen at 30.

Since FIGURE 6 depicts a cord connector, the main body is somewhat deeper to house and insulate the full lengths of the blade-receiving twin contacts 73, 74, seen in FIGURE 7, depending from the plate 70 formed integral with terminal plate 71, perforated and threaded at 72 to receive the terminal or clamping screw having the head 25.

The upper or rear portion of bottom body 60 is recessed similar to body 10, has the flat bottom wall 62 to support the contact- terminal units 70, 71, and clearance holes 64 for the screw shanks. Either one (as shown) or both contact springs 73, 74 of a unit has the edges of its upper, straight portion serrated or toothed as shown at 75. The teeth are sloped toward the plate 70 and sized and spaced apart as seen in FIGURE 6 to at least partially bury themselves in the walls of the plastic material of the passage 66, through the bottom body 60, when pressed therein preferably before the plastic material has entirely cooled after being molded. This arrangement provides adequately for securing the contact-terminal units in the insulating material of the bottom body 60 so that struts such as shown at 26 in FIGURES 4 and 5 are unnecessary.

The absence of such struts permits a greater universality for the cover 28 since it is not required to have specific areas for engagement with struts. The latter may be variously disposed in the main section of insulation, depending upon the number of terminals required as well as certain specific positioning thereof.

The cover or top body 28 shown in FIGURE 6 has a cable clamp identical to that shown in FIGURES 1 to 4 inclusive, and the same reference characters are applied thereto.

FIGURE 8 illustrates the changes necessary in an attachment-plug blade to eliminate the need for positioning it by means of a strut and the cover plate. The parts whose reference characters are primed are identical to those of the same unprimed numbers on FIGURE 5, but two sets of teeth, on opposite edges of the blade are shown at 14", and obviously the slots 20 seen in FIG- URE 4 must be adjusted in width to accommodate the teeth, which function the same as those shown and described in connection with FIGURE 7. They may be relied upon to provide firm anchorage for the bladeterminal plate units.

It will be appreciated that if a single-piece insulating body is preferred to the two-part one shown, that the cable grip described above can readily be molded integrally therewith just as it is with the cover 28.

Referring to FIGURES 916 and 19 there is illustrated 6 another embodiment of this invention comprising a top body and a bottom body 102. The bottom body has a fiat bottom 104 and a circular side wall 106. As in the other embodiments, it may 'be molded provided proper mechanical strength and insulating qualities are obtained thereby.

The plug, as in the other embodiment illustrated in FIGURES 15, is conventional having a pair of parallel blades 108 and a somewhat longer grounding prong 110 One of the plug blades 108 is shown in its complete form in FIGURE 16 where it will be noted that in addition to the elongated straight flat blade portion 112, it has at right angles thereto a flat portion 114 terminating in a vertically extending bifurcated screw-carrying portion 116 forming a U-shaped slot 118 between the bifurcations 120120 with the open portion upward. It will be noted that the bifurcations 120-120 each extend out beyond the vertical blade portion 112. The lower horizontal face 122 of each bifurcationacts .as a bearing surface when the plug blade is positioned in the bottom body 106.

Plug blade 108 is mounted in bottom body 106 by passing the elongated blade portion 112 down through cavity 124 and out small aperture 126 in the bottom portion of the bottom body. The blade 108 is held in this position as illustrated in FIGURE 19 by means of slots 128 and 130 (FIGURE 14), having shoulders which support the lower faces 122-122 of bifurcations 120120.

Referring to FIGURE 19, the cavity 124 is somewhat enlarged at its top portion to accommodate and form a support for the threaded end 134 of screw 136 which is horizontally disposed in the slot 118 of plug blade 108 with its head portion outward of the bifurcations and the threaded portion extending across cavity 124. A wire-grip:- ping nut 138 is threadedly carried on the screw 136 and is adapted to grip a conductor passed downwardly through aligned aperture 140 in body cover disk 142. Access to screw 136 is provided by an opening 144 in the side wall 106 of the bottom body 102. There such plug blade arrangements are provided in the bottom body 102, two of the blade type 108 and one of the grounding blade type 110.

It will be noted that the cover disk 142 as shown, first in FIGURE 15 and then in FIGURE 19, is held down in position by expanding the top portion of integral plug 146 down over the peripheral edge portion of the aperture disk 142. In this particular embodiment the bottom body is made of nylon and can be readily so deformed. It is the cover disk 142 which engages the upper end portion of the "bifurcations 120 that serves together with the shoulders in the bottom of slots 128 and 130 to maintain the plug blades in position.

The bottom body 102 is also provided with three threaded holes 148 adapted to receive screws 150 to retain the top body 100 in assembled position with respect to the bottom body 102.

To cover, mechanically protect and electrically insulate the terminals a top body 100 is provided, having the same general configuration as the lower body 102. As shown in FIGURE 9 the vertical outer surface 152 of the top body is serrated by means of longitudinally extending vertical grooves. The top body in this embodiment is rziiade from nylon although other materials could be use A cable-clamp assembly for holding the conductor cord or the like, rigidly and to releive the terminal and individual conductors of strain is integrally formed with the top body. As illustrated in FIGURES 9, 1'0, 11 and 19, on opposite sides of the cord opening in the top portion of the top body there are integrally provided flexible extensions 162 projecting upwardly as continuations of the wall of opening 160, said extensions generally being of less than 90 degrees in extent with respect to the periphery of the opening 160. A substantial distance above the top surface of the top body 100 these extensions have rela- 7 tively fiat upper ends 164. Each of the extensions 162 is substantially thickened in a radial direction a substantial distance downwardly from the top 164. This thickened area is found with a concave inner face 166 to somewhat conform to the cord which is to be gripped between these confronting concave faces 166 of clamping members 168.

To provide clamping means, each of the clamp members 168 is provided with a pair of laterally extending wings 170. Each wing has an aperture 172 aligning with a respective aperture in the wing confronting it. The confronting wings are parallel to each other and are adapted to clamp the cord between the clamping members in the manner illustrated in FIGURES 1 and 2 and described previously.

As best illustrated in FIGURES 1113, the top body 100 includes a vertical cylindrical side wall 176 with a top portion 178. This top portion has three screw-carrying countersunk holes 180 found in therein and extending downwardly into enlarged portion 182 of the side wall 176. This enlarged portion 182 is offset from the lower edge of the side wall 176 as shown in FIGURE 13.

Referring to FIGURE 19, the bottom body 102 is sized to fit within the top body 100, in the manner indicated. The three portions of the bottom body having threaded holes 148 adapted to register with holes 180 in the top body are offset with respect to the top surface of the bottom body so that when the top and bottom bodies are brought together, the respective offset portions of the two bodies engage each other to limit inward movement of the bottom body. With the two bodies 50 arranged, screws 150 are introduced and the assembly is complete.

This particular embodiment is also adapted for use with a female contact arrangement as illustrated in FIGURES 17, 18 and 20. The female contact assembly 190 as shown in FIGURE 17 comprises a pair of contact springs 192, 194 mounted on a U-shaped bracket 196 so that they are in parallel spaced-apart position. The U-shaped bracket 196 includes a base portion 198 with upstanding parallel bifurcated portions 200 and 202. The height of bifurcated portion 202 is less than that of 200. The bifurcated portions form slots 204 and 206 respectively, aligned to receive a screw 208 supported by the base of both slots as shown in FIGURE 20.

The bottom body 210 of this embodiment is cylindrical in shape and is adapted to be assembled to a top body like that assembled with the male contact unit. The bottom body 210 has an enlarged vertical hole 212 extending from the top thereof and terminating in a small hole 214 providing access for the male plug blade. As in the hottom body of the embodiment of FIGURES 9-15 and 19, the body 210 is provided with threaded holes 216 to receive screws to retain the top and bottom bodies in assembled position. Those holes are formed in an offset portion for the same assembly purpose as the previous embodiment of FIGURES 9-15 and 19. The body 210 is also provided with a top cover disk 220 having wire holes 222 and adapted to be riveted onto the body as shown in FIGURE 20 by heading the upstanding plug portion 224 of FIGURE 18 so that it bears down on the cover disk 220 to hold in on the bottom body.

Referring to FIGURE 20, there is illustrated the assemblage embodying the female contact unit. The female contact assembly is assembled in the bottom body 210 in the same general manner as the plug blade 108 in the embodiment shown in FIGURE 19. The screw 208 is positioned in the U-shaped bracket 196 and threadedly carries a wire-engaging nut 230. The top body 232 fits down over the bottom body 210 and is secured thereto by means of screws 234. A plug blade 238 is shown inserted in the spring contact unit 190.

I claim:

1. In an electrical connector cap, in combination, a disc of a semi-rigid type plastic having a central cord hole therein, a pair of arcuate cable clamps having lateral wings and connecting means arranged and sized to clamp an electric cord passing through said hole, a thin relatively flexible portion connecting each clamp to but spaced from the disc with its inner face substantially aligned with the wall of said bore, said disc, clamps, wings and flexible portions being all integrally molded.

2. The invention as set forth in claim 1 and wherein the disc of a semi-rigid type plastic having a central cord hole therein comprises a two-part body, the first body part housing terminal plates and connector screws, said first body part having cont-act elements extending from each terminal plate, and the second body part covering said terminal plates and screws and having a central cord hole therethrough.

References Cited UNITED STATES PATENTS 963,733 7/1910 Kliegl 339107 2,259,328 10/1941 Sinninger 339l 2,393,481 1/1946 Smith 339--277 X 2,927,297 3/1960 Hubbell 339--196 MARVIN A. CHAMPION, Primary Examiner.

EDWARD C. ALLEN, ALFRED S. TRASK, RICHARD E. MOORE, Examiners.

Claims (1)

1. IN AN ELECTRICAL CONNECTOR CAP, IN COMBINATION, A DISC OF A SEMI-RIGID TYPE PLASTIC HAVING A CENTRAL CORD HOLE THEREIN, A PAIR OF ARCUATE CABLE CLAMPS HAVING LATERAL WINGS AND CONNECTING MEANS ARRANGED AND SIZED TO CLAMP AN ELECTRIC CORD PASSING THROUGH SAID HOLE, A THIN RELATIVELY FLEXIBLE PORTION CONNECTING EACH CLAMP TO BUT SPACED FROM THE DISC WITH ITS INNER FACE SUSTANTIALLY ALIGNED WITH THE WALL OF SAID BORE, SAID DISC, CLAMPS, WINGS AND FLEXIBLE PORTIONS BEING ALL INTEGRALLY MOLDED.

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