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Publication numberUS2975392 A
Publication typeGrant
Publication dateMar 14, 1961
Filing dateJan 26, 1959
Priority dateJan 26, 1959
Publication numberUS 2975392 A, US 2975392A, US-A-2975392, US2975392 A, US2975392A
InventorsLudwig Louis
Original AssigneeLudwig Louis
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Electrical connectors
US 2975392 A
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Description  (OCR text may contain errors)

March 14, 1961 LUDWIG ELECTRICAL CONNECTORS 2 Sheets-Sheet 1 Filed Jan. 26, 1959 INVENTOR. tours C uoms A FOR/V675 United States Patent ELECTRICAL CONNECTORS Louis Ludwig, New York, N.Y. Eagle Electric Mauuiacturing Co., 23-10 Bridge Plaza 5., Long Island City, N.Y.)

Filed Jan. 26, 1959, Ser. No. 789,172

2 Claims. (Cl. 339-99) This invention relates to electrical equipment and more particularly to a novel electrical connector of the piercing contact type.

It is an object of the present invention to provide a connector of the character described which is extremely simple in construction and yet absolutely reliable in use.

it is another object of the present invention to pro vide a connector of the character described having relatively few parts and wherein a small fraction of a turn of one such part relative to another is all that is required to effect an electrical connection between an unstripped, i.e., insulated, electric wire and the connector.

It is another object of the invention to provide a connector of the character described which is easy and inexpensive to manufacture and simple, sturdy and durable in use.

It is an ancillary object of the present invention to provide a piercing contact type socket having all of the foregoing attributes.

It is another object of the present invention to provide a socket of the character described having a novel arrangement for hanging from a wire, line or other obicct.

Other objects of the invention in part will be obvious and in part will be pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements and arrangements of parts which will be exemplified in the connector hereinafter described and of which the scope of application will be indicated in the appended claims.

in the accompanying drawings in which there are shown various possible embodiments of the invention,

Fig. l is a perspective view of a socket embodying the present invention. the same being shown in open position and in association with two unstripped electrical wires to which it is to be connected;

Fig. 2 is a view similar to Fig. l, but showing the socket connected to the wires;

Figs. 3 and 4 are enlarged sectional views taken substantially along the lines 3-3 and 4-4 of Fig. 1;

Fig. 5 is an enlarged sectional view taken substantially along the line 5-5 of Fig. 2;

Figs. 6, 7 and 8 are sectional views taken substantially along the lines 6-6, 7-7 and 8-8, respectively, of Fig. 5; and

Fig. 9 is a perspective view of a detail of the construction.

The present invention is shown and will be described with respect to a piercing contact type socket adapted to be hung from a wire, line or other object, such for example, as the branch of a tree. It will be understood, however, that the invention is not to be taken as limited to the specific type connector shown and edscribed herein since the invention is adaptable for use in various other applications and the present drawings and description are merely illustrative of the invention and not limitative of its scope.

2,975,392 Patented Mar. 14, 1961 Referring now in detail to the drawings, the reference numeral 10 denotes a socket constructed in accordance with the instant invention. The socket includes a hollow husk l2 and an elongated ram 14. The rim of the husk is flared outwardly slightly and the top of the ram has a longitudinal slot, the two parts generally being related to one another in contour and shape so as to resemble a bell. The husk and ram are fabricated from a light, strong thermosetting plastic such as a phenolformaldehyde resin, for example, Bakelite."

The inner surface 16 of the husk is provided with molded threads 18 for receiving the base of a light bulb. At the top 20 of the husk two spaced diametrically opposed, segmentally circular concentric wells 22 of equal radius are provided, each communicating with the interior of the husk through a passageway 24 (see Figs. 3 and 5). A fiat, electric, resilient side contact 26 on the innere wall of the husk extends through and protrudes from the passageway 24 of one well terminating at its tip in a prong 28 that projects into the well a considerable distance (see Fig. 6). The threads 18 are gapped under the contact 26, said contact being secured to the wall in any conventional manner as by frictionally embedding the outer end thereof in a cavity 30 in the wall and at the top thereof bending over side flanges 32 at the base of the prong against the bottom surface of the well with which the side contact is associated (see Figs. 3 and 7).

A flat, electric, resilient central contact 34 is also provided in the husk, said contact having its outer end secured in the other well 22. The securement of the central contact is entirely conventional and in the embodiment shown constitutes both the bent over flanges 36 near the upper end of the contact, these being in en gagement with the bottom surface of the associated well, and an arm 37 which engages the underside of the top 20 of the husk. An integral prong 38 projects from said upper end of the central contact 34 a considerable distance into said associated well. Said contact extends downwardly from the passageway 24 of said well and has its lower end 40 projecting downwardly and transversely centrally of the husk (see Figs. 3 and 5).

The wells 22 are located between a central annular wall 42 at the top of the husk and two diametrically oppositely disposed side posts 44 spaced from the wall 42 and extending upwardly at the periphery of the husk at each side thereof.

The ram includes a pair of spaced, segmentally circular, concentric diametrically opposed shoes 46 on the bottom surface 48 thereof, the shoes having their ends tapered into the bottom surface 48. Each shoe includes an elongated concentric guide channel 50 (see Fig. 8).

Pursuant to the instant invention, the ram is mounted for independent oscillatory and axial movements with respect to the husk, the ram being bodily translatable parallel to the axis of rotation thereof. It is a feature of the instant invention that the ram mounting is such that axial movement of the ram can be performed with or without oscillatory motion thereof or vice versa. Each shoe 46 is adapted to cooperate with a different prong to press down an unstripped wire lying on each prong whereby the latter will pierce the insulation of the wire and contact the core thereof. Accordingly, each shoe is spaced the same distance from the axis of rotation of the ram as its associated well, the channel of each said shoe being so located as to be disposed directly over the prong in its associated well when the shoe. is disposed over the same. In the embodiment shown, both pairs of associated shoes and wells are located the same distance from the axis of rotation of the ram, this being convenient rather than necessary.

A centrally located depending circular boss 52 is formed on the bottom surface of the ram, said boss being rotatable in a cylindrical depression 54 formed in the top surface of the husk by the wall 42. An annular seat 56 constituting the top of said wall surrounds the depression. Said seat is provided with a pair of radial keyways 58 extending across the seat perpendicular to the wells. The seat also includes a second pair of radial keyways 60 extending parallel to said wells. The keyways are 90 apart.

Each side post 44 of the husk has a vertical upwardly extending stop 62 at its trailing edge (assuming clockwise rotation in a top view as shown in Fig. 7). A double wedge cam 64 runs from the leading edge of each post to a depressed dwell 65 that separates the cam and stop.

The bottom surface of the ram includes at each end thereof a wedge-shaped arcuate cam follower 66 located radially outwardly of the adjacent shoe 46. On one side of each cam 66 a shoulder 68 and notch 70 are provided (see Fig. 8), the shoulders and notches being reversely located on opposite ends of the ram. The shoulders are "so positioned that when the ram is rotated in the direction of the arrow A to closed position of the ram in a manner to be described hereinafter, each stop 62 will be abutted by a different shoulder and be received in a different notch.

Two radial diametrically opposite keys 72 on the bottom of the ram extend outwardly from the periphery of the boss, said keys being perpendicular to the length of the ram. The sides of the keys are chamfered. Said keys are dimensioned for nice reception in the keyways 58, 60.

An elongated, central, vertical through opening 74 is provided in the ram extending from the top surface there- 'of through the boss 52. Said opening is in the shape of a slot 76 having a central cylindrical section 78 with a diameter greater than the width of the slot. The slot is coincident with the longitudinal axis of the ram. The top 20 of the husk includes an elongated centrally disposed through opening 80 in the depression 54, said opening being in the shape of a slot 82 of approximately the same dimensions as the slot 76. Said opening also includes a central section 84 having diametrically opposed overlapping quadrantal notches 86. The combined width of the notches is greater than the width of the slot 82 and is approximately equal to the diameter of the cylindrical section 78 of the opening 74. The notches have shoulders 88 which are spaced from one another axially of the length of the slot 82. The shoulders 88 face in a direction opposite to the direction of rotation of the ram as it moves toward the closed position of the socket, as indicated by the arrow A.

An elongated locking element 90 is provided for permanently captively securing the ram to the husk with the same mounted for independent oscillatory and axial movement with respect to the husk. Said element comprises an elongated flat metal strip including an elongated shank 92 terminating in a T-headed lower end 94 which includes two lateral extensions 96 the upper edges of which are perpendicular to the length of the shank. Near the upper end of the shank a pair of outwardly extending wings 98 is provided, the lower edges thereof being perpendicular to the length of the shank. The distance between the facing edges of the extensions and wings 96, 98 is of importance, as will be explained and described hereinafter.

The thickness of the shank 92 is less than the widths of the slots 76 and 82 of openings 74 and 80. The width of the shank is less than the lengths of said slots and small enough for the shank to be rotatable in the cylindrical section 78 of the opening 74 and in the notches of the central section 84 of opening 80. The aforesaid width of the shanks, however, is greater than the width of the slot 82. Accordingly, the shank is fully rotatable in the cylindrical section of the opening 76 but only rotatable a quarter turn in the -opening 80.

The lower end 94 of the locking element has the same thickness as the shank 92, and its width at the extensions 96 is less than the lengths of the aforesaid slots 76, 82 but greater than the combined widths of the notches in the opening 80. As a result, said end can be inserted into and withdrawn from opening 80 only when said end is aligned with the length of the slot of said opening. A central circular bore 100 is formed in the interior of the husk below and in communication with the opening 80. Said bore has a diameter greater than the width of the lower end 94 of the locking element. The roof of said bore is provided with a pair of seats 102 constituting shallow slots in said roof and each having an edge thereof in registry with a different shoulder 88. Moreover, adjacent each said seat the roof of the bore is fashioned in the shape of a ramp 104, said ramp abruptly terminating at the associated seat.

A corrugated annular leaf spring 106 is located on the top surface of the ram over opening 74 and a metal washer 108 is disposed over the spring. The central opening of the washer is in the form of a slot 110 of a length sufficient to pass the lower end and shank of the locking element 90 and of a thickness such that said shank is not rotatable therein. Slot 110 has a shorter length than the width of the shank at the wings 98 which, therefore, cannot pass through the same. The spring 106 has a large central opening 112 through which the lower end of the locking element can be passed and in which the shank is rotatable (see Figs. 3, 4 and 5).

A cardboard disc 114 is disposed between the bottom surface of the boss 52 of the ram and the bottom of the depression 54 of the husk, said disk having a side-opening slot 116 of a width sufiicient to receive the shank (see Fig. 9).

The slot 82 of opening 80 is so positioned in the husk that when the ram is in a position wherein its keys 72 are located in the keyways 60, the slot of opening 74 is aligned longitudinally with the slot 82 of opening 80. Also, the distance between the facing edges of the extensions and wings 96, 98 of the locking element is slightly less than the distance from the top surface of the washer 108 to the seats 102 with the spring 106 in uncompressed condition.

The socket is assembled as follows: the ram is placed on the husk with the boss 52 received in the depression 54 and the keys 72 seated in the keyways 60. At the same time the shoulders 68 of the earns 66 abut their associated stops 62 on the posts 44, and the slots of openings 74 and 80 will be aligned. Before placing the ram on the husk, the locking element is assembled to the ram by sliding its lower end through the slot 110 in washer 108, opening 112 in leaf spring 106 and the opening 74 of the ram. Also, the disc 114 is fitted onto the shank of the locking element below the boss 52. As the ram is placed on the husk as set forth above, the lower end of the locking element is slipped through the slot 82 of opening 80 of the husk and when said element is in serted as far as it will go, i.e., when the wings 98 abut the too surface of Washer 108. the upper edges of extensions 96 of the lower end will be disposed in said slot 82 slightly above the roof of the bore 100. The shank is then pushed downwardly against the resistance of the leaf spring until the extensions 96 are brought slightly below the roof of the bore whereupon the locking element is rotated in the direction of the arrow A until the broad faces of the shank abut the shoulders 88 of the notches 86. It is to be noted that rotation of the shank is only possible in this one direction from its inserted position because movement thereof in the opening 80 is limited by the notches. As the shank is rotated, the upper surfaces of extensions 96 ride upon the ramps 104 in the bore against the pressure of the leaf spring which is further compressed as the shoulders 96 move along the ramps until the shoulders 96 snap into the seats 102. The seats have a depth such that the spring is still under compression after the shoulders 96 have snapped into place. Next, the bore is filled with hot pitch 118 which on cooling seals the shank of the locking element in position, i.e., prevents it from turning with its lower end eaptively held in the bore by abutment of the upper edges of the extensions 96 thereof against the roof of the cup. The disc 114 prevents the hot pitch from getting into the depression 54 of the husk and thus interfering with operation of the connector.

As is apparent from the foregoing, construction and assembly of the present device are quite simple. Moreover, after assembly the ram and husk cannot be separated from one another accidentally or deliberately.

The snap-in arrangement of the shoulders 96 in the seats 102 though not necessary is desirable because it holds the shank in position during assembly and until the pitching operation is completed.

The depth of the wells and the extent of projection of the prongs 28 and 38 thereinto will be governed by the sizes of wire with which the socket is to be used. It is necessary that when the ram is in closed position as shown in Fig. 2 the shoes thereof have forced the wires onto the prongs sufficiently for the latter to have pierced the insulation of the wires and reach the core thereof (see Fig. 6).

As is well known, it is a requirement of insurance underwriters that hanging electrical fixtures or connectors not be supported by the electric wires extending therefrom. Accordingly, where connectors and sockets of the general type described hereinbefore are desired to be hung, conventionally an extra wire or element for hanging purposes is secured to the socket. This has the drawbacks of being expensive because an extra element and securement are required, these being liable to loosening. Pursuant to an ancillary feature of the present invention, the socket described hereinbefore is adapted to be hung by a simple, inexpensive, rigid structure which complies with the requirement of the insurance underwriters. To accomplish this an integral hook 120 is provided at the top end of the locking element. As is readily apparent, forming the hook with and as part of the locking element is a relatively simple and inexpensive manufacturing operation. Also, the hook will be rigid and not liable to loosening, so that all of the drawbacks of conventional hanging sockets are avoided while at the same time the underwriters requirements are met.

The socket described hereinabove has an open or inoperative position (see Figs. 1, 3 and 4) and a closed or operative position (see Figs. 2 and 5). It is in the closed position at the time manufacturing assembly is completed. As already mentioned, in this position of the socket the keys 72 of the ram are seated in the keyways 60 of the husk. Movement of the keys into and out of these keyways is facilitated by the chamfers on the sides of the keys. Also in the closed position, the cams 66 of the ram are disposed with their shoulders 68 abutting the stops 62 of the associated side posts of the husk, the stops themselves being received in the notches 70 adjacent the shoulders 68. The earns 66 and 64 co-act as the keys ride out of the keyways 60 to permit oscillatory movement of the ram with respect to the husk.

The open position of the ram is defined by seating of the keys 72 in the keyways 58, movement of the keys into and out of these keyways being smoothly permitted by the aforementioned chamfers at the sides of the keys. The open position is maintained by the bias of the spring 106, the springs pro-compression serving to prevent the ram from accidentally moving with respect to the husk in the open and closed positions of the socket.

Since the adjacent keyways 58 and 60 are 90 apart, only a quarter turn of the ram is necessary to go from the open to closed position of the socket and vice versa. It is to be noted that the ram can be turned beyond its open position; however, abutment of the sides of the ram against the backs of the stops 62 of the side posts of the husk prevents further movement of the ram in a direction away from its closed position.

As is apparent from the foregoing description, movement of the ram into and out of its closed position and into and out of its open position causes axial translation thereof with respect to the husk because of the interaction of the keys and keyways and the cams 66 and 64. Between the open and closed positions the ram only has oscillatory movement.

The socket operates as follows: the ram is turned to open position and an electrical wire 122 is laid on the prong in each well. At this time a portion of each wire will extend above the well in which it is disposed (see Fig. 3) and will lie in the path of movement of the shoes of the ram which extend into the wells in the closed position of the socket (see Fig. 5). The ram is then twisted to closed position and as the shoes led by the tapered ends thereof pass over the wires they press the wires into the wells so that they are pierced by the prongs sufliciently to allow the latter to contact the core of the wires (see Fig. 6). The dorsal surfaces of the wires fit into the channels 50 of the shoes. Moreover, it will be observed that at the last moment of closing of the ram the earns 64, 66 lift the ram away from the wire and then allow it to rather suddenly press the wire against the prongs. The slight free axial movement of the ram under the influence of the leaf spring creates an impulse that assures eflicient penetration of the insulation, particularly when light wire is used. Moreover, the high spot at the center of the double wedge cam 64 prevents the ram from, accidentally turning in an opening direction when any size wire within the range that can be handled by the socket is located in the wells and the ram is in its closed position. The socket can he opened by deliberately turning the ram to open position and pulling the wires off the prongs.

It is apparent from the foregoing that a novel and extremely useful connector is provided pursuant to the instant invention. Connectors embodying the same can be readily and simply electrically secured to insulated wires without full revolutions of one part with respect to the other. Indeed, the whole connecting operation is accomplished by a mere quarter turn of the ram and the contact is both instantaneous and sure. Moreover, the connection cannot become loose due to vibration of the connector or rough usage. Additionally, the elements of the device cannot be lost prior to use.

Still further, the present device is simple and inexpensive to manufacture, easy for even a layman to use, and rugged and long-lasting. Also, the socket shown and described herein can be hooked onto a line or wire by an inexpensive sturdy structure complying with insurance requirements.

It thus will be seen that there has been provided an electrical connector which carries out the various'objects of the invention and is well adapted to meet the conditions of practical use.

As various possible embodiments might be made of the above invention and as various changes might be made in the embodiments above set forth, it is to be understood that all matter herein described or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, I claim as new and desire to secure by Letters Patent:

1. An electrical connector comprising a first electrically non-conductive part, a second electrically nonconductive part, said first part having a projection on a surface thereof, said second part having a well in a surface thereof, the first part including a non-circular through opening, the second part including a non-circular through opening, means mounting the first part adjacent the second part for oscillation with respect to the sec- 0nd part with said openings adjacent one another between an operative position in which the projection extends into the well and an inoperative position in which the projection is disposed out of and is angularly displaced from the well, an electrically conductive prong extending into the well in a direction substantially toward the projection when the parts are in operative position, said prong being connected to an electrical contact, both through openings being disposed on the axis of oscillation of the parts, said mounting means constituting an elongated locking element having a shank extending through said openings and including a shoulder disposed adjacent one side of said adjacent openings and an abutment disposed on the other side of said openings, the shoulder being receivable in less than all transverse dimensions of the non-circular opening of the part to which it is adjacent, the elongated locking element being permanently secured to the second part, the first part being slidable along and longitudinally of said locking element, spring means disposed between the abutment and the part to which it is adjacent, said spring means biasing the first part against the second part, the first part being oscillatable about the shank between operative and inoperative positions of the connector, and cam means integral with said parts for axially moving said parts away from one another against the action of the spring means as said parts are oscillated to approach operative position, said cam means being constructed and positioned thereafter to allow the parts to be moved together by the spring means just as the projection swings into registry with the well, whereby in said operative position the projection is forced into the well by the spring means.

2. An electric connector as set forth in claim 1 wherein one of the parts is provided with a key and wherein the other of the parts is provided with angularly spaced key ways, said key being received in a key way in operative position of the electrical connector and said key being received in a different key way in inoperative position of the connector, said key and key ways being independent of the mounting means.

References Cited in the file of this patent UNITED STATES PATENTS 1,307,240 Christopher June 17, 1919 1,709,357 Ludwig Apr. 16, 1929 1,909,412 Ludwig May 16, 1933 2,620,376 Benander Dec. 2, 1952 2,869,101 Benandcr Jan. 13, 1959

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1307240 *Jan 15, 1919Jun 17, 1919 Topher
US1709357 *Jun 9, 1927Apr 16, 1929Louis LudwigElectric wire tap
US1909412 *Aug 20, 1929May 16, 1933Louis LudwigElectric outlet with wire tap
US2620376 *Jul 3, 1950Dec 2, 1952Gen ElectricLamp socket
US2869101 *Mar 29, 1956Jan 13, 1959Gen ElectricPin-type lampholder
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3500294 *Feb 16, 1968Mar 10, 1970Lyall ElectricIntegral rubber lampholder
US3597725 *May 15, 1969Aug 3, 1971Beck Henry TElectrical socket
US4257664 *Mar 8, 1979Mar 24, 1981Eagle Electric Mfg. Co., Inc.Screw socket for an electric lamp
US4653829 *Jan 27, 1986Mar 31, 1987Lamont Romanus MQuick connect lamp socket
US4778409 *Dec 24, 1986Oct 18, 1988Noma Inc.Screw in lamp holder
US4841420 *Jun 20, 1988Jun 20, 1989Woodhead Industries, Inc.String lights for construction sites
US5190469 *Jun 3, 1992Mar 2, 1993Mui Cheuk YElectrical cord end connector
US5453023 *Mar 18, 1994Sep 26, 1995The Whitaker CorporationTerminal block for interconnecting an uninsulated conductive lead portion to another conductor
US7806718 *Oct 23, 2007Oct 5, 2010Blazing Products Inc.Electrical connectors and methods of connecting
WO1993024972A1 *May 18, 1993Dec 9, 1993Cheuk Yu MuiElectrical cord end connector
U.S. Classification439/409
International ClassificationF21V21/002, H01R4/24, F21V19/00
Cooperative ClassificationH01R4/2404, F21V19/00, F21V21/002
European ClassificationF21V19/00, F21V21/002, H01R4/24A