US3694790A

US3694790A - Duplex locking receptacle

Info

Publication number: US3694790A
Application number: US118955A
Authority: US
Inventors: Robert L Martin
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1971-02-25
Filing date: 1971-02-25
Publication date: 1972-09-26
Anticipated expiration: 1989-09-26

Abstract

A duplex grounded convenience outlet is provided adapted to receive power blades in twist lock relationship. Simplicity of connector construction and disposition is achieved through use of symmetrical connector strips and feed through mounting bracket with mounting of grounding contacts thereon.

Description

[ 51 Sept. 26, 1972 United States Patent Martin l-lubbell.......................339/33 .339/14 [54] DUPLEX LOCKING RECEPTACLE [72] lnventor:

Drapkin.......................174/53 .339/14 Robert L. Martin, Cranston, RI.

General Electric Company Feb. 25, 1971 5/1962 Howells......................

Assignee:

[22] Filed:

Primary ExaminerMarvin A. Champion Assistant Examiner-Robert A. l-lafer Attorney-Paul E. Rochford [21] Appl. No.: 118,955

Related US. Application Data [63] Continuation of Ser. No. 771,829, Oct. 30,

[57] ABSTRACT A duplex grounded convenience outlet is provided 1968, abandoned.

[52] US. adapted to receive power blades in twist lock relation- .339/14 R, 339/156 R, 339/191 M Int. Cl. p- Simplicity Of Connector Construction and disposition is achieved through use of symmetrical connector strips and feed through mounting bracket with mounting of grounding contacts thereon.

[58] Field of Search........339/14, 123, 125, 132, 133, 339/156,163,164, 31, 33,166,191

[56] References Cited UNITED STATES PATENTS 7 Claims, 8 Drawing Figures 2,032,980 3/1936 Fitzgerald..................173/330 PATENTED I97? 3.694.790

SHEET 1 BF 2 i 'IIIIIHHHII" lhve htow obert L. Martin,

b5 f fl five M Attorne DUPLEX LOCKING RECEPTACLE This application is a continuation of Ser. No. 77 l ,829, filed Oct. 30, I968, now abandoned.

The construction of duplex convenience outlets to accept locking blades of the twist-lock type presents a number of problems because of the relative size of the blades which must be used in order to obtain a locking action and also because of the movement which must occur after the blades have been inserted into the outlet to effect the locking interconnection of the blades with the connectors in the device. Efforts to construct duplex locking outlets have led to structures which have a comparatively high number of specialized parts, which are expensive to form, and which present complex assembly problems and add to the cost of the final product. The difficulties of forming parts which accept the locking blades in each of the two outlets of a duplex structure is increased when it is also sought to adapt the duplex outlet to split circuit wiring. Such split circuit wiring involves the effective electrical separation of the wire connectors and associated contacts of each of the outlets of the duplex outlet structure.

It is accordingly one object of the present invention to provide a locking device duplex receptacle susceptible to split circuit wiring.

Another object of the present invention is to provide a grounded locking device duplex receptacle having a bracket supported within an insulated housing.

Still another object of the present invention is to provide a grounded duplex locking device which employs a single metal part as wire contact strip in both left-hand and right-hand contact of the device and simultaneously facilitates split circuit wiring.

Still another object of the present invention is to provide a locking device duplex receptacle, the wiring terminals of which are placed non-symmetrically with respect to the insulating housing.

A further object of the present invention is to provide for split circuit wiring with a breakoff tab held within the confines of the outline of the device.

Other objects and advantages of the invention will be in part apparent and in part pointed out in the description which follows.

In one of its broader aspects the objects of the invention may be achieved by providing a duplex receptacle adapted to split circuit wiring comprising an insulating housing having a base and a cover a plurality of cavities in the base adapted to receive two sets of contacts for twist-lock blades,

a pair of contact strips, each strip having break-off tabs in the middle thereof, wire terminal connectors adjacent the break-off tab, and power blade engaging fingers at each end of said strip,

said strips being disposed in said cavities to expose one break-off tab and adjoining wire terminal connectors along each side of said insulating housing base,

an insulating spacer extending the width of said insulating housing and disposed over the wire connecting portions of said cavities,

a mounting strap, said strap having perforated end sections for mounting in wall box, and said strap having extending between the end sections solid portions conforming to the side walls of said base and being sandwiched between the base and cover of said device.

The invention and the manner by which it is carried into effect will be made clearer from the description which follows.'The description is given with reference to the accompanying drawings in which:

FIG. 1 is an exploded perspective view of the device of the present invention showing the juxtaposition of the component parts thereof.

FIG. 2 is a top plan view of the device with the cover in place.

FIG. 3 is a top plan view similar to FIG. 2 but with the cover removed.

FIG. 4 is a view similar to that of FIG. 3 but with the bracket and insulating spacer removed.

FIG. 5 is a vertical sectional view taken along the lines 5-5 of FIG. 2.

FIG. 6 is a vertical sectional view taken along the lines 6-6 of FIG. 2.

FIG. 7 is an external elevation view of the side of the assembled device.

FIG. 8 is an exploded view of a contact strip and associated parts.

Referring first to FIG. 1, there is shown in an exploded view the parts employed by the duplex convenience outlets of the present invention superimposed in an alignment in which they would be placed prior to being joined in the assembled device.

The cover 10 is shown to have two sets of prong receiving

arcuate slot openings

12 and 14 and to have a screw receiving hole 16 at the mid-portion to permit a cover plate to be mounted over the cover of the outlet. Side recesses 18 are seen to have the same general configuration as the side recesses 28 in an insulating spacer 30.

A mounting strap 20 has screw slots 22 at end sections thereof, said screw slots being located to permit the mounting screw to attach the mounting strap and the devices attached to it into a receiving wall box. The end sections of the strap are also seen to have detachable plaster ears such as 23. Between the two end sections, the strap consists of longitudinally extending side strips 24 having a cross strip 26 at a middle region therebetween and having two large openings 29 and 32. A grounding tab 34 is formed from metal punched out of opening 32 and the tab has a threaded center hole adapted to receive a ground wire screw 35.

The mounting strap also has two side indentations 36 proximate the cross strip 26 and located in registry with the side indentation 18 of the cover 10. Two grounding contacts 38 are attached to the strap, one being attached at the cross piece 26 and the other being attached at the end section 21.

Beneath the strap 20 is shown, also in registry with the other piecesof the exploded view of FIG. 1, an insulating spacer 30 having two recesses or indentations 28 conforming generally to those 18 of cover 10. The upper surface of the indented side portion of insulator 30 provides an insulating ridge 42 which conforms to and rests within the side indentation 36 of the strap 20 when the device is assembled. The insulating ridge 42 provides in essence an outer wall for the surface of the strap presented at the edge which defines recess 36. A further function of the insulating separator 30 is performed by the inverted pocket shown in phantom at 44. This pocket receives the boss 45 of the contact 40 and retains the contact in place in the insulating housing when the break-off tab 46 is removed.

A bridge 47 between the two side portions of the separator nests in the channel 48 in the insulating base 60 to restrain the separator 30 against longitudinal motion along the lengths of the outlet device after the separator is installed in place in the insulating base 50.

Referring now to the contact strips 40, it will be seen in FIGS. 1 and 8 that the strips are made up of an angled piece of metal 52 which is symmetrical about a transverse line extending through break-off tabs 46.

Contacts

53 and 54 are formed separately and mounted on the angled iron 52 at tabbed end portions thereof 50 by a rivet or other suitable attachment means. Further, it will be seen that the

contact

53 and 54 are disposed generally parallel to each other in the sense that a plane passing between the faces of contact fingers 53a and 53b of the contact 53 will be found to be parallel to a plane passing between the faces of

contact fingers

54a and 54b.

Screws 55 are also shown to be mounted at the screw terminal portions 56 of the contact strip 52 and to engage the wire clamp 67 seen best at the left hand side of FIG. 1 and in FIG. 8. The clamps move responsive to the turning of screws 55. Referring now to the insulating housing 60 at the lowermost part of FIG. 1, it is seen that housing is provided which has a plurality of compartments adapted to receive and retain the wire connection and blade contact portions of the contact strips 40. It will be realized that firm retention of these parts in base 60 is important in that the break-oi? tab 46 may be removed prior to the wiring operation. In such case it is important that the parts of the contact strip and the contacts themselves be held firmly in their respective positions within the insulating housing in order to avoid electrical fireworks.

Referring now to FIG. 4, the position of the current carrying contacts 53 and 54in the cavities may be seen to be a disposition which places the contacts around the two centers 62 and 65. These centers are the axis of screw holes extending through the base to provide access of attachment screws 62a and 650 from the under side or back of the insulating housing to extend through the base to be threaded into the underside of the cover 10 at the centers. The attachment screws are best seen in their relation to the base and cover in FIG. 5.

Referring again to FIG. 4, the

contacts

53 and 54 are seen to be nested within the

cavities

63 and 64. Grounding contact 38 is not shown nested within cavity 68 because the mounting strap is not shown in place in FIG. 4, but its relationship to the cavity is seen in FIG. 3 and FIG. 5. Similarly, the second grounding contact 38 attached to the cross piece 26 is disposed within the cavity 69 when the strap 20 is in position on the base 60 as seen in FIG. 5.

Referring back again to FIG. 1, it will be seen that four legs 49, integral with and depending from the insulating separator or barrier 30, serve to provide a separating wall between the portions of the

cavities

63 and 64 in which the interlocking blade is inserted and the portion in which wire is attached to the wire terminal means. This wire terminal means includes the wire contact 57, the wire terminal portion 56, and the screw 55. These walls 49 prevent movement of a wire inserted into one of the wire entry ports from inadvertently being placed in a position to interfere with the movement of the interlocking contacts as for example an interlocking blade entering the cavity 63 and interlocking with the contact 53.

The screw terminals 56 are positioned in the side openings 61 located along the sides of the insulating housing 60. The cavity 68 for the grounding contact is interconnected with a side opening 68a into which is positioned the downwardly extending grounding tab 34. Tab 34 serves as a ground wire terminal.

It will be apparent from a consideration of the location of the wire terminals 56 and the screw members 55 in FIG. 7 that the two screws and two wire terminals, as well as the break-off link 46, are not located at the longitudinal center of the outlet structure shown in FIG. 7 7. Thus it is apparent that while the cover 10 is symmetrically formed and symmetrically located with respect to the strap 20, that the screw terminals 56 are not centrally located along the length of the device and that accordingly the contacts mounted on the terminal strip are not symmetrically located along the length of the outlet structure. It is important to appreciate that the feasibility pursuant to this invention of forming a contact strip which can be symmetrically disposed about a transverse center through the break-off tab depends on the location of this contact strip off center with respect to the longitudinal symmetry of the duplex outlet structure as shown in FIG. 7. Accordingly what is submitted to be novel in the structure of the present invention is the provision of a contact strip which is symmetrically formed about a longitudinal center point but which is located off center with respect to the duplex outlet structure in which the contact strip provides the blade contact and wire terminal for electric supply through the outlet.

The form of the contact strip with the screws 55, the wire clamps 57 and the

contacts

53 and 54 removed is seen best in FIG. 8 where the simple symmetry of its construction is evident. The wire terminals 56 are provided with the upward extending tabs 45 which, as explained above, lock into the recesses 44 in the insulating spacer 30. The relation of the screw 55 and wire clamp 57 to the screw terminal 56 is evident in FIG. 8. Also, the contact mounting tabs 50 at the ends of the contact strips 52 are shown in their relation to the

power blade contacts

54 and 53.

It will be evident from a consideration of the contact strip shown in FIG. 8 that it has a generaly symmetry about a lateral line extending through the break-off tab 46 and further that, when positioned in the insulating base 60, although the contact strips are not centrally positioned in the outlet base 60 in a longitudinal direction, they are symmetrically positioned on each side of a central mid-line through the base. Accordingly, the contacts have a longitudinal symmetry as well as a side-by-side symmetry so that a single contact strip, as shown in FIG. 8, can be used in each half of the duplex structure. The use of a single form of contact strip in both halves of the outletpermits a great economy in manufacture of the outlet while adding to the structure the features pointed out of split circuit wiring as well as great facility in wiring.

The

contacts

53 and 54 are positioned as indicated above generally parallel to each other on each of the contact strips that is at each end of a single contact strip. Actually all four of the contacts in the duplex outlet are of the same form and may be used interchangeably at any tab 50 simply'by giving them the proper orientation relative to the strip before attaching them to the tab. This adds further to-the economy of the overall construction. The contact 53 once properly oriented is joined to the tab 50 of the strip'52 by a rivet such as 51 shown in FIG. 8.

It is apparent that while the foregoing description is given with reference to a specific structure, the device is adapted to be formed in a number of modifications which permit its use with a wide variety of

arcuate slots

12 and 14 which accommodate interlocking'blades of configurations which are shaped to conform to-the voltage and current levels for which the device is to be used. Thus, while the grounding contact 38 is shown mounted in a particular location on the crosspieces of the strap and generally at the lateral center of the strap, it is apparent that a grounding contact can be at tached to the cross strip 26 and the end strip 21 at other locations which permit other configurations of grounding contact to be employed. Generally it is the grounding contact configuration which provides the key to the voltage and current level for which a device is used. Because the grounding contact can be mounted at a variety of locations within the

grounding cavities

68 and 69 and can be mounted at a variety of locations on the cross strips 26 and 21, the device of the present invention can be employed in supplying power of a corresponding variety of voltage and amperage combinations. Also, because the mounting of the grounding contacts is internally of the outlet structure, the insulating base is reduced in its volume and the outlet structure will fit into a smaller space than that resulting from other arrangements. This is important in the use of the device in mounting boxes of a variety of shapes and sizes in permitting its use in almost all construction of wall boxes and other receptacles for such outlets.

It is also apparent from the structure shown in the Figures that the backwiring using the wiring clamps 57 is possible but that a wire may also be wrapped around the screw 55 where it is exposed with the wire terminals 56 at the side of the device. This alternative in wiringis provided by the structure of the present invention. In use of the wire clamp, the depending leg 49 of the insulating spacer effectively prevent the inadvertent entry of a wire inserted through the wire entry port 67 into the cavity in which the contacts must move as part of the interlocking action.

Further, when the external wiring is employed by wrapping the wire around the screw 55, the insulating ledge 42 presents contact of the wire with the surface of the strap within the recess 36 in the side of the strap. 3 Reference should be made to application Ser. No. 771,731 of the same inventor filed concurrently herewith, now US. Pat. No. 3,566,337, for teaching of a distinct invention relating to a locking duplex outlet structure of the same general appearance as the structure illustrated herein.

What is claimed is:

l. A contact strip for a duplex locking receptacle said strip having a center break off tab,

wire connector means proximate said break off tab,

and power blade contacting end sections,

said strip having a base portion which is symmetrical longitudinally about a lateral mid-line passing through said break off tab and said strip having separable blade contacts mounted asymmetricallyonsaid blade contacting end sections said contacts having opposed'finger contacts and the center plane'between the fingers of each contact mounted on said strip being parallel and being set at an acute angle to the length of said strip to dispose said finger contacts asymmetrically with reference to said strip.

2. A grounding bracket for a duplex convenience receptacle adapted to receive locking power blades,

which comprises an elongated strip of metalhaving twoend sections,

screw slots in said end sections for mounting screws,

side strips extending'longitudinallybetween said end sections, and being separated by a distance greater than the width of a-plurality of locking blades,

said side strips being joined at mid-portions thereof by a cross-strip defining openings on either side of said cross-strip large enough to admit a plurality of locking blades,

and grounding contacts attached at said cross-strip and one end section of said bracket and extending into the openings of said bracket.

3. A grounding bracket for a duplex convenience receptacle adapted to receive locking power blades, which comprises,

a metal strip having anopening fora mounting screw in each end section thereof,

two openings large enough to admit a plurality of locking blades in said strip and a cross piece between said two openings,

grounding contacts attached at said cross piece and one end section of said bracket and extending into the openings of said bracket,

and a metal tab formed to depend from one side of said bracket, said metal tab being formed integrally with said bracket and depending from an inside edge of said opening from metal bent out of the plane of the strip in forming on of said blade admitting openings.

4. A duplex receptacle adapted to split circuit wiring which comprises an insulating housing having a base and a cover, a

plurality of cavities in said base adapted to receive and retain two sets of contacts for twist lock blades,

a pair of contact strips, each strip having a break off tab at the middle thereof,

wire terminal connectors proximate the middle of said strip, and power blade engaging fingers at each end of said strip,

said strips being disposed in said cavities to dispose the wire connectors in connector portions of said cavities and to expose one break off tab and adjoining wire terminal connectors along each exterior side of said insulating housing base,

an insulating spacer extending the width of the insulating base and disposed over the wire connector portions of said cavities,

said spacer having depending legs, said legs providing separating barriers between the contact portions and the wire connector portions of said cavities,

6. The structure of claim S'wherein edges of said spider are exposed at the sides of the device and provide an insulating spacer between the break off tab and the strap.

7. The structure of claim 5 wherein the strap is laterally narrowed in the region proximate the break off tab.

Claims

1. A contact strip for a duplex locking receptacle said strip having a center break off tab, wire connector means proximate said break off tab, and power blade contacting end sections, said strip having a base portion which is symmetrical longitudinally about a lateral mid-line passing through said break off tab and said strip having separable blade contacts mounted asymmetrically on said blade contacting end sections said contacts having opposed finger contacts and the center plane between the fingers of each contact mounted on said strip being parallel and being set at an acute angle to the length of said strip to dispose said finger contacts asymmetrically with reference to said strip.

2. A grounding bracket for a duplex convenience receptacle adapted to receive locking power blades, which comprises an elongated strip of metal having two end sections, screw slots in said end sections for mounting screws, side strips extending longitudinally between said end sections, and being separated by a distance greater than the width of a plurality of locking blades, said side strips being joined at mid-portions thereof by a cross-strip defining openings on either side of said cross-strip large enough to admit a plurality of locking blades, and grounding contacts attached at said cross-strip and one end section of said bracket and extending into the openings of said bracket.

3. A grounding bracket for a duplex convenience receptacle adapted to receive locking power blades, which comprises, a metal strip having an opening for a mounting screw in each end section thereof, two openings large enough to admit a plurality of locking blades in said strip and a cross piece between said two openings, grounding contacts attached at said cross piece and one end section of said bracket and extending into the openings of said bracket, and a metal tab formed to depend from one side of said bracket, said metal tab being formed integrally with said bracket and depending from an inside edge of said opening from metal bent out of the plane of the strip in forming on of said blade admitting openings.

4. A duplex receptacle adapted to split circuit wiring which comprises an insulating housing having a base and a cover, a plurality of cavities in said base adapted to receive and retain two sets of contacts for twist lock blades, a pair of contact strips, each strip having a break off tab at the middle thereof, wire terminal connectors proximate the middle of said strip, and power blAde engaging fingers at each end of said strip, said strips being disposed in said cavities to dispose the wire connectors in connector portions of said cavities and to expose one break off tab and adjoining wire terminal connectors along each exterior side of said insulating housing base, an insulating spacer extending the width of the insulating base and disposed over the wire connector portions of said cavities, said spacer having depending legs, said legs providing separating barriers between the contact portions and the wire connector portions of said cavities, a mounting strap, said strap extending along the perimeter of said insulating base and being sandwiched between said base and an insulating cover.

5. The device of claim 4 wherein said strap has a transverse mid-portion over said spider and said strap has mounted at said transverse mid-portion and at an end thereof grounding locking contacts, said contacts depending from said strap into grounding cavities in said base.

6. The structure of claim 5 wherein edges of said spider are exposed at the sides of the device and provide an insulating spacer between the break off tab and the strap.