US2748363A

US2748363A - Push-in type terminal unit for lamp receptacles

Info

Publication number: US2748363A
Application number: US439280A
Authority: US
Inventors: Victor R Despard
Original assignee: Pass and Seymour Inc
Current assignee: Pass and Seymour Inc
Priority date: 1954-06-25
Filing date: 1954-06-25
Publication date: 1956-05-29
Anticipated expiration: 1973-05-29

Description

United States Patent PUSH-IN TYPE TERMINAL UNIT FOR LAMP RECEPTACLES Victor R. Despard, Syracuse, N. Y., assignor to Pass & Seymour, Inc., Syracuse, N. Y., a corporation of New York Application June 25, 1954, Serial No. 439,280

9 Claims. (Cl. 339-95) This invention relates to electric wiring devices and more particularly to connecting, continuing and terminating apparatus for use therewith.

It is a general object of the present invention to provide novel and improved devices of the type described having unique circuit connecting, continuing and terminating apparatus associated therewith.

More particularly it is an object of the present invention to provide a novel and improved electric fixture or lamp receptacle of the ceramic type'for mounting as a box cover and having littings including automatic wire gripping terminals and lamp base contacting tongues.

An important object of the present invention resides in the unitary construction of each of the duplicate littings whereby it includes as an integral unit a pair of similar wire grippings spring terminals adapted to automatically engage and hold a bared wire end inserted therein, and a tongue adapted to act as a lamp base contact engaging element.

Another important object of the invention consists in .providing on each fitting a wire gripping spring terminal of the short open-ended slot type wherein integral means areprovided to prevent misalignment of the two wings of the wire grip to insure holding under all conditions and also to prevent the possibility of wing collapse or wire end cutting on excessive tension on the wire.

A further object ofthe invention resides in the provision of a unit iitting which combines two laterally spaced, automatic, spring type, wire grippers connected flexibly to each other through a looped strap which carries the socket terminal, whereby each gripper assumes its proper relationship to the supporting and side restraining walls of the insulation base.

A still further object of the invention consists in the provision of a spring type Wire gripper of extreme shortness achieved by connecting the gripping wings together at one end only, restraining the wing side edges in the insulation and providing integral supports on the free ends of the wings to resist collapse on wire withdrawal tension.

Other and further objects and features of the invention will be more apparent to those skilled in the art upon a consideration ofthe accompanying drawing and following specification wherein is disclosed a single exemplary embodiment 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:

Fig. l is a fragmentary rear elevation of a wiring device incorporating the features of the present invention shown with the rear insulation'cover plate and one of the connector-terminal fittings removed to illustrate the contiguration of the insulating base for cooperation therewith;

FigA 2 is a section taken on the plane indicated by line 2`2 of Fig- 1;

Fi'g- 3` is a fragmentary section taken on the plane of line 3-3 in Fig. 1 and illustrating the cooperation of the 2,748,363 Patented May 29, 1956 wire gripper wings with the side wa'll of their receiving slot; and g Fig. 4 is a view of a connector-terminal fitting unit before installation, looking from the inner or open end and illustrating the collapse preventing feet on the wing ends.

In my copending application Serial No. 378,380, for Convenience Outlet with Improved Wire and Plug Blade Gripping Means, tiled September 3,. 1953, there is disclosed terminal means for quickly and automatically connecting conductors to electrical wiring devices of the house and oice building type, where the bared end of each conductor wire is held by spring gripping means, instantly providing both for mechanical and electrical connection between the conductor and the electrical parts of the apparatus to which it is to be connected by the simple operation of inserting the end of the conductor through an opening in the back Wall of a wiring device andpushing it in for a short distance. That particular disclosure involved a dual convenience outlet and permitted the 'elongated construction ofthe wire gripping mechanism with the longitudinally disposed wire engaging slot closed at both ends by metal portions integral with the deilectable wings spaced apart less than the thickness of the wire to be engaged. The closing of both ends of this slot imparted a rigidity to the connector unit which is not possible in a shorter unit such as is required in certain other types of wiring devices. It is therefore the purpose of the present invention to provide a short type of wiring-unit, spring-wing, connector of the open end type and to pro vide thereon means to compensate for the lack of slot closure at one end so that the operation is the full equal to that disclosed in the earlier application.

Referring now to the drawing, it will be seen that the invention is embodied in the conductor and adjacent insulation parts of a wiring device usually referred to as the box cover type, i. e., it is a porcelain or plastic molded lamp holder or receptacle somewhat greater in diameter than the usual 3% or 4 inch wiring box and may be substituted for the common metal cover thereof, thus providing an outlet for a light at the box in addition to what other functions the box may perform in housing the junctions of other conductors in the wiring system.

For the purpose of covering such a box the wiring device is composed of a base 10 having a somewhat greater diameter than the box and having an integral central extension 11 provided with an axial well 12 for the reception of the screw base of a conventional incandescent lamp. In the present construction the circular walls of' the Well 12 are provided with a molded thread 13 for cooperating with the threads of the lamp which screws directly into the well. In the rear face of the base 1li, which is hollow in various places for the sake of lightness, there is a large central hollow 14, generally rectangular in form, as seen in Fig. l, and composed of a plurality of irregular smaller depressions of varying depths. This hollow is adapted to be covered, as seen in Fig. 2, by a closure plate 15 of some rigid, insulating plastic material of vonly sufficient thickness to provide the'necessary strength for retaining the conductor parts in position, as will later appear. This cover plate is arranged to bear on the central platform 16 dividing the hollow into two major areas and itself being only lower than the plane of the border 17 around the hollow by the thickness of the plate 15. This platform and shelves 18 at the ends of the hollow provide for sustaining the cover while to insure proper orientation the

extensions

19 and 20 of the shelves have different widths to accommodate correspondingly sized tongues on the two ends of the cover plate. The cover plate is secured in position in any satisfactory manner, as by screws 21, suitably engaged in the material of the base.

On each side of the central platform 16 is an electrical fitting unit 24, the two being identical, so that only one will be described. One" is shown in position at the right in Fig. 1 while at the left the insulation is exposed to permit consideration of the shapes of the various compenent parts of the depressions in the base.

Each fitting, which may be defined as a duplex wire gripping and lamp base contacting device, is composed of a unitary punching or stamping of spring material of good conductivity such as high grade or Phosphor bronze. It is shaped from a single piece of sheet metal to the form illustrated in the several figures. Thus looking at Fig. l there are two

wire gripper sections

25, 26 of similar construction, each rectangular in plan and joined by a lateral neck 27 near the outer end of its inner edge to one arm 28 of a strap-like loopv or bight which extends toward vthe center of the base until it meets the edge of the platform 16 when it is turned down as parts 29, seen in Figs. 2 and 3. These two parts 29 join each other and merge into the elongated narrow tongue 30, preferably having a stud 31 pressed into the outer end.

The

downturned portion

29, 29 of the loop is accommodated loosely in channel 32 extending in an axial direction into the base toward the front and adjacent the widened center portion of platform 16. It extends into well 12 through the narrower and thinner slot 33 for the tongue and is positioned to cause it to enter against the circular wall of the well. Thus the tongue on each fitting extends for a substantial distance into the receptacle for the lamp base, and the one intended to engage the screw shell of the base is received in a channel or groove 34 through the threads 13 for the purpose. The stud and outer end of this tongue are sprung inwardly so that the stud is insured of contact in the bottom of the threads of the lamp base screw shell as it is inserted in the receptacle. The other tongue, after insertion, is bent ldownwardly sharply over the edge of its slot 33 so as to lie along. and slightly sprung up from the bottom with the stud projecting outwardly to engage the center contact of the lamp base. Thus the two idenical fittings provide for the screw shell and central contacts of the lamp socket and the loops or bights formed of the

parts

2S, 29, 29, 28 and their extensions 27 to the wire grippers 2S provide for a very tiexible resilient connectien between these grippers so that each is permitted to float in its own recess portion and assume the required positions as the result of the use to which it is being put. The connecting parts offer substantially no restraint to this.

The recess portions allocated to the individual wire grippers are seen at 35 in Figs. 1, 2 and 3 and are indented longitudinally into platform 16, have parallel sides 36, rectangular inner ends 37 and a pointed opposite end 38. They are of considerable depth at the size of their tops and then the sides taper to the narrow bottom 39. Each pair of recesses 35 open from the bottom of a larger one 40 which lowers the fitting below the cover 15.

To understand the purpose of the shape of opening 35 consideration must be given to the construction and operation of the wire gripper. Each is composed of two parallel strips or wings 42 attached only by one of their ends to the at part 43 of the tting extending alongy its outer edge. This part 43 is provided with an upturned flange 44 for its full length, as seen in Figs. l, 2 and 4. This part therefore has considerable stiffness. The wings 42 are spaced for the greater part of theirV length and at their outer ends by the slo-t 45 of less width than the thickness of the smallest wire to be used and gripped by the device, but this slot widens out to the opening 46 at the inner ends of the wings, narrowing the width of the wings to give them added resilience in respect to their base portion 43. Each wing is deected or bent to lower the edges of the slot 45 below the general plane of the fitting and as far as possible this is done without changing the wings from plane surfaces except at the areas of intieetion adjacent the portion 46 of the slot. These wings'in their plane form are clearly seen in Fig. 3 and the inflection areas where they merge with the area 43 are also visible in this figure.

The ends of the gripper wings 42 are narrowed as at 47 and bent upwardly 90 to provide the tips or feet 48, seen in elevation in Fig. 4. Their ends are cut off parallel to the general upper surface of the fitting at slightly less height than that of the ange 44.

The depressions 35 have their side walls 36 extending for a short distance at right angles to the plane of the base, as seen in Fig. 3, so that the outer edges of gripper tongues 42 can closely engage them whereby the wings are prevented from spreading when a wire is inserted into the funnel-like entrance section presented by them, as seen in Fig. 3. These same edges of the blades engage the sloping wall 50 merging with walls 36 to support the wings during wire insertion.

The two fittings are held in position by the cover plate 15 which engages against the upper edges of their flanges 44, as seen in Fig. 2, the depressions 40 being sufficiently deep for that purpose as also revealed in that figure. The areas 43 adjacent the anges are seen resting on holsters 51 adjacent the ends of the depressions 35 to further hold the blades in position. The sloping walls of these depressions 35, indicated by the reference characters 50, have considerably greater included angles than between the wings so that these are never prevented from exing to the degree necessary to grip any size wire.

The cover plate 15 has a hole through it at 54 directly above the slot 45 between the wings of each fitting and near the outer end thereof and sized to receive any of the usual conductor wires used in household wiring, i. e. from size 16 to size l2, and the bared end of one of these may be pressed through the hole and pushed between the wings, flexing them to spread the slot. The end of the wire is received in and its movement stopped by the bottom of the tapered circular well 55 just beneath the hole 54.

It will be seen that the action of pressing a wire through the slot between the wings cannot spread them laterally because of their engagement with the walls 38 of the recess in which they are housed, and they must be thereby constrained to rotate in opposite directions about their outer edges as fulcra to open the gap for the insertion of the wire, increasing the flexing where they are joined to the part 43 of the fitting. Any effort to withdraw the wire only tends to close the slot and cause the wing edges to grip more tightly. It is, however, highly important that the inner edges of the wings be maintained in alignment for otherwise the wire might be released by widening of the slot by displacement of one wing in respect to the other. Moreover they should not be permitted to be drawn too tightly together by withdrawal tension on the wire for fear of cutting the latter. The feet 48, referred to heretofore, serve the dual purpose of preventing misalignment and preventing wire cutting, since on the slightest withdrawal tension they are drawn to and engage the inner face of the cover plate 15 and maintain the ends of the wings in alignment. The feet have flat ends, which engagey the cover and. prevent the wings from rotating toward each other to such an extent as to achieve a cutting position.

In the event that it should be desired to release a conductor held by the spring wings of a gripper, a second opening 56 isv provided in the cover plate adjacent the inner end' of each slot 45 into which an appropriate tool may be inserted to force the slot wider and' thus release the conductor. If such a tool is of. steel it will be of sutiicient hardness not to be gripped like the copper conductor and can thus be withdrawn. It is' convenient if this opening 56- is a transverse slot to receivethe tip of a knife blade since the taper of the endl of the bladefacilitates the opening of the slot and the later withdrawal of the tool after the wire is released.

Two grippers are provided on each fitting unit since in many cases it is desired not only to connect the wiring device into the electrical system but to provide for continuing the circuit and the added terminal on each fitting provides for this in an extremely simple manner. In addition it permits a balanced and symmetrical construction of the ttings which are identical and can hence be manufactured from the same die.

I claim:

l. A push-in type wire gripping terminal for electric wiring devices comprising in combination, a base of insulating material having a depression therein, a sheet metal wire gripper comprising wings with spaced parallel adjacent edges and cach having one end attached to a conductor strap, the opposite ends of said wings being free and each having a foot normal thereto, said wings being inclined laterally and oppositely to guide a wire end into the slot between and spacing said wings, the outer edges of said wings being confined against lateral spreading by engaging the walls of said depression below the surface of the said base, and a cover for said base adapted .to hold the said gripper in position thereon, said cover having an opening therein for the entrance of a wire into said slot, said wing feet substantially engaging said cover to prevent misalignment of the wings or wire cutoff on excessive withdrawal tension.

2. Electric wiring apparatus of the type described having in combination, an electrical contact, means for connecting an electrical conductor wire to said contact comprising a strip of resilient metal extending from said contact having outer longitudinal edges and a longitudinal slit midway between them forming spaced flat wings having free and attached ends, the attached ends of the wings being oppositely twisted to incline the wings out of the plane of the strip to guide the end of a bared wire into the slit, means acting adjacent said free ends to hold the edges of the slit in alignment when tension is applied to the wire and rigid means engaging the said outer longitudinal edges to prevent lateral spreading of the wings.

3. Electric wiring apparatus of the type described having in combination, an insulating housing having a body and a back cover, an electric contact in said body, means for connecting an electric conductor wire to said contact comprising a strip of resilient conductor metal end-connected to said Contact, supported by said body and having an open ended longitudinal slot therein bordered by wings inclined oppositely from the strip outer edges and yieldable to accept the bared end of a conductor wire through the slot between the wings to be gripped by the wing edges to resist withdrawal, the cover having a wire opening therein in alignment with the slot to direct the bared end of the wire into the slot, the body having vertical walls engaging said outer edges to prevent the wings spreading laterally and the free ends of the wings having feet normally substantially engaging said cover to maintain slot edge alignment when the inserted wire is tensioned.

4. In a box cover type of lamp receptacle, in combination, a moulded base having a lamp base receiving shell integral with and extending from the front face thereof, moulded lamp engaging threads in said shell having a longitudinal groove therethrough, a large hollow in the back face of the base opposite said shell, diametrically opposite passages through said base from the bottom of the shell to the hollow, one forming an extension of said groove, a separate extension of said hollow adjacent and communicating with each of said passages, duplicate fittings one in each extension and each having integral therewith; a contact tongue extending through its passage and into the receptacle, a pair of laterally spaced wire gripping devices and a flexible strap connecting said grippers together and to said contact tongue; and a cover closing said hollow, secured to said base and engaging and holding said fittings in position.

5. The device in claim 4 in which each wire gripping device comprises a rectangle of sheet metal having an upturned flange at one end and a longitudinal slot normal thereto and bisecting most of the remainder thereof, forming wings, said slot being widened at its inner end and the wings being twisted adjacent said widened portion to form a trough for guiding a conductor wire into said slot.

6. The device of claim 5 in which the said flanges are engaged by said cover to hold the fittings in position.

7. The device of claim 6 in which the free ends of said tongues have feet extending parallel to said llange and toward said cover for engagement therewith when a wire gripped by the wings is pulled in a withdrawal direction.

8. The device of claim 5 in which the said wings are prevented from spreading by lateral engagement with walls of said base and the included angle between said twisted wings is substantially greater than whereby attempted withdrawal of a gripped wire causes the wings to grip it tighter.

9. The device of claim 8 in which said cover has a wire inserting hole above the narrow portion of each slot and an adjacent transverse slot for the insertion of a releasing blade.

References Cited in the file of this patent UNITED STATES PATENTS 2,206,799 Barton July 2, 1940 2,259,740 Del Camp Oct. 21, 1941 2,550,237 Franklin Apr. 24, 1951 FOREIGN PATENTS 564,065 Germany Nov. 23, 1932 659,316 Great Britain Oct. 25, 1951