Connector plug for power distribution track

[57] ABSTRACT

The present invention relates to a connector plug attachment for use with a power distribution track of the type having an open channel housing insulated conductive conduits. The connector is characterized by the ability to be electrically and mechanically coupled to the track by a single operation, notably a rotation of elements of the connector plug relative to the track. The plug includes a pair of wings or flanges for rotation into mechanically locked engagement with portions of the track and a pair of contact portions rotatable into electrically coupled relation with the conduits of the track, a lost motion coupling being interposed between the flanges and contacts whereby, upon rotation of a single drive or locking element on the plug, the contacts and flanges are appropriately positioned to secure the desired mechanical and electrical coupling.

Claims, 7 Drawing Figures

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PATENTED JUL 15 1975

3,894,781

SHEET

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PATENTEOJUL 1 5 1975 SHEET

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PATENTED JUL 15 1975

3,894,781

SHEET

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3,894,781

CONNECTOR PLUG FOR POWER DISTRIBUTION TRACK

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is directed to a plug member, and more particularly to a plug member adapted to be connected to a power distribution track. More particularly, the invention is in the field of plug members for use in power distribution tracks of the types illustrated, for example, in U.S. Pat. Nos. 2,346,074 and 3,286,052, such tracks comprising generally an elongated aluminum or like metallic extrusion in the form of a channel having a slot or opening, the channel containing recessed electric conduits.

The plug is intended to be mechanically and electrically coupled at virtually any point along the length of the track, it being understood that the plug may support a lighting fixture or may be used to provide an outlet for a tool or other electrical appliance.

2. The Prior Art

The concept of providing elongated power distribution tracks and plugs connectible at any desired position therealong is known, for example, in the above noted patents. Typically, tracks of the sort referred to are secured along the ceiling structure of a room, although, of course, they may be otherwise located.

As will be evident, where the power distribution track is positioned in a relatively inaccessible location, such as a ceiling, a user desirous of effecting connection to the track, must of necessity climb a ladder, chair, or like support to gain access to the track. In accordance with the two above noted patents, plug apparatuses are described which are structurally and functionally efficient for their intended purpose in that excellent mechanical and electrical connections to the track may be effected.

The plug fixtures of both of the noted patents, however, require substantial amounts of manipulation for actually completing the coupling between the plug and track, such manipulation including, for example, the carrying out of sequential operations and/or operations requiring two hands for their satisfactory performance.

SUMMARY

The present invention may be summarized as directed to an improved plug adapted for mechanical and electrical connection to a power distribution track by simplified, one-hand operation facilitating the task of a user who is required to climb a ladder, stand on a chair or otherwise be perched in an unstable position to gain access to the track.

The plug apparatus comprises a housing including a stop portion or plate adapted to engage against the flanges leading to the interior of the power distribution channel. The housing includes a barrel member which may be rotated after appropriate positioning of the housing to drive a pair of locking wings or flanges through a predetermined angular arc, to effect mechanical engagement of the locking flanges and the track flanges.

An insulated plug member carrying contact portions is rotatably mounted within the barrel and is directly connected to the barrel or drive means, such that rotation of the barrel is likewise communicated to the plug.

A lost motion coupling is interposed between the barrel and the locking flanges, whereby the plug carrying the contacts may be rotated a greater arcuate distance than the locking flanges. It will thus be perceived that both operations, viz. mechanical coupling of the housing to the track and electrical coupling of the contacts carried by the plug to the conduits within the track are accomplished by a single rotary movement applied to the barrel or drive means.

With the foregoing in mind, it is an object of the invention to provide an improved plug assembly for attachment to a power distribution track, the plug assembly being characterized by the fact that both electrical and mechanical couplings are accomplished responsive to a simple rotary movement of a single part of the plug.

A further object of the invention is the provision of an improved plug assembly of the type described including a barrel rotatably mounted on the housing of the plug, rotation of the barrel being effective simultaneously to engage mechanical locking flanges of the plug with flanges of the track, securely to connect the parts, and electrically connect contact portions of the plug and the conduits in the track.

According to the invention, these objects are accomplished by the arrangement and combination of elements hereinafter described and particularly recited in the claims.

In the drawings, in which are shown one or more of the various possible embodiments of the several features of the invention:

FIG. 1 is a fragmentary perspective view of a track section and portions of the plug assembly;

FIG. 2 is a plan view taken in the direction of the arrows 2—2 of FIG. 1;

FIG. 3 is a side elevational view of a lighting fixture supported on a track section;

FIG. 4 is a magnified horizontal section taken on the line 4—4 of FIG. 3;

FIG. 5 is a vertical section taken on the line 5—5 of FIG 4;

FIG. 6 is a vertical section taken on the line 6—6 of FIG. 4;

FIG. 7 is a horizontal section taken on the line 7—7 of FIG. 5.

Referring now to FIG. 1, there is shown at 10 a track section of a type known per se, and consisting essentially of an elongated aluminum extrusion including side walls 11, 12, and a horizontal web 13. An opposed pair of inturned flanges 14,15 terminate in spaced relation defining therebetween a downwardly open slot S.

The web 13, side walls 11 and 12, and flanges 14, 15 define a generally C-shaped, downwardly open channel within which is mounted an appropriately configurated vinyl or like insulating member 16 carrying conduits 17 and 18 connected to the electrical mains.

The plug assembly 19 consists essentially of a housing including a stop plate or portion 20 adapted to lie against the flanges 14, 15, and a barrel or drive portion 21, in torque transmitting connection with locking flanges 22 for mechanically coupling the plug to the flanges 14, 15 of the track assembly, and contact ears 23, 23 for effecting electrical coupling to the conduits 17, 18. The plate 20, which preferably has a cork or like insulating cushioning layer 24 on its track-adjacent face, is provided with a keying flange 25 adapted to ride within the slot S between flangers 14, 15, to prevent relative rotation of the plate and the track.

3,894,781 movement of the sleeve 30 is experienced until the barrel has been rotated through about 70°, at which point the lead end of the screw 36 will engage against the terminal or trailing end of the slot 42, at which point the screw picks up the sleeve and imparts rotary movement thereto (see FIG. 7).

An understanding of the locking action is best appreciated by a comparison of FIGS. 2 and 4.

In FIG. 2, the contact ears 23 and locking flanges 22 are disclosed in an aligned position, permitting the same to be inserted into the interior of the track through the slot S. After insertion, attachment is effected by rotating the barrel 21, which rotation may be facilitated by the use of the drive lever 40, such rotation causing an initial anti-clockwise movement of the contact ears 23, bringing the same progressively closer to the conduits 17, 18.

The sleeve 30 carrying the locking flanges 22, as noted, remains essentially stationary during the initial 20 stages of rotation of the barrel. After about 70° of rotation, the screw 36 reaches the terminal end of the slot 42 and imparts rotary movement to the sleeve 30, driving the wings or locking flanges 22 into a tight frictional engagement over the flanges 14, 15 of the track 10, the 25 parts now being in the position shown in FIGS. 4 and 7. As a result of the use of a cork or like resilient and compressible surface 24, a tight frictional engagement, free of rattles, is obtained between the plug assembly 19 and the track 10.

Optionally and preferably, the lead edges 22α of the locking flanges 22 may be beveled or chamfered in an appropriate direction to facilitate the passing of the flanges 22 of the plug over the flanges 14, 15 of the track with an appropriate wedging action.

It will be understood that prior to assembling of the plug onto the track, appropriate electrical connections are made to the conductors 35 extending from the contacts 23.

It will be further appreciated that a lighting fixture L ⁴⁰ may be connected to the plug assembly prior to attachment of the plug assembly to the track, whereby mounting of a lighting fixture to the track is accomplished by merely mounting the plug assembly in the manner above set forth.

As a manner of effecting mounting of the fixture L, the cylindrical boss 29 may include at its lower end an externally threaded portion 43. A mounting cap 44, having an internally threaded portion 45, may be threadedly connected to the portion 43. Preferably a clutch spring 46 is compressed between the opposed shoulders 47 of the boss and 48 of the cap 44 to provide frictional resistance to turning between the parts, wearresistant thrust washers W being preferably interposed between the spring ends and the shoulders 47, 48 to prevent wear.

The yoke Y of the lighting fixture L is attached to the cap 44, as by a pair of machine screws 49, 49', extending upwardly through holes in the yoke into complementally tapped holes 50, 50'.

The outer surface 51 of the boss 29 may include a vertically extending rib 52, of sufficient length to lie in the path of one of the lamp supporting screws, e.g., the screw 49 (see FIG. 6) whereby it will be observed that as a result of the interaction of the screw and rib, the angular extent through which the cap 44 may be rotated relative to the remaining assembly is limited. Such arrangement prevents accidental or inadvertent

Preferably the stop plate 20 may include a longitudinally extending, polarizing groove 26 adapted to receive a complemental polarizing rib 27 formed on the flange 14, whereby the plug may be received within the channel of the track only in a desired and properly po- : larized orientation.

The plug may include a grounding spring 28, adapted to be received within the channel to ground the plug to the track 10, which is itself at ground potential.

As best seen from FIGS. 5 and 6, the barrel or drive I portion 21, which is essentially cylindrical, is rotatably mounted on a vertical cylindrical boss 29 extending downwardly from the plate 20, the plate and boss being preferably of integral die cast construction.

The locking flanges 22 extend radially outwardly : from the upper end of a sleeve member 30, the main body of which is cylindrical in horizontal section, the sleeve member riding within the boss 29 forming part of the housing.

A generally cylindrical insulating plug or stem 31 is ' rotatably mounted within the sleeve 30, the stem preferably including an insulating plastic shield member 32, the upper end of which shield is frictionally received on depending skirt 33 at the lower end of the plug 31. The stem or plug 31 is provided with a pair of vertically extending slots 34, 34, within which slots are received Lshaped conductor members 35, 35, the uppermost end portions of which are bent outwardly and define the contact ears 23.

It will be appreciated that as thus far described, the drive or barrel member 21 may be rotated about the boss 29, sleeve 30 carrying locking flanges 22 is free to rotate within the boss, and the contact supporting stem 31 is likewise free to rotate relative to the sleeve 30, boss 29 and barrel 21. Driving connection between the barrel 21, sleeve 30 and stem 31 is provided by a transversely directed drive screw 36.

The inner end 37 of the screw 36 is received in a complementally threaded aperture 38 formed in the stem 31. The head of the screw 36 lies within a circular aperture 39 formed in the barrel. It will thus be seen that when the barrel 21 is rotated, as by manipulation of the driver lever 40 projecting from the barrel, the rotary movement is communicated through the screw 36 to the stem 31.

The boss 29 is provided with an arcuate slot 41, of an angular extent of just over about 90°. Since the screw 36 passes through such slot, it will be observed that the total rotary movement which may be imparted to the barrel and hence to the plug is limited to about 90°. The screw 36 passes through a further arcuate slot 42 in the sleeve 30. The angular extent of the arcuate slot 42 is substantially less than 90°, being in the order of about 70°.

When the plug assembly 19 is in position for insertion (FIGS. 1 and 2), the contact ears 23 and locking flanges 22 are substantially in alignment, as are the trailing edges of the arcuate slot 41 in the boss 29 and 42 of the sleeve 30. Since the angular extent of the arcuate slot 42 is, as noted, about 20° less than that of the slot 41, it will be apparent that initial rotation of the barrel 21 in an anti-clockwise direction (when viewed in the orientation of FIGS. 1 and 2) will be accompanied by a concomitant anti-clockwise rotation of the contacts 23 carried by the stem 31 since the screw 36 directly couples the stem and barrel. Since the screw 36 passes freely through the slot 42 in the sleeve 30, no

3,894,781 unthreading of the lamp L from plug assembly 19, while still permitting a substantial amount of relative rotation between the parts.

From the foregoing it will be appreciated that there is provided a novel plug assembly which may be securely electrically and mechanically attached to a power distribution track by one-hand operation. A simple rotation of the barrel 21, which is connected directly to the contact carrying stem 31 and through a lost motion coupling provided by slot 41 to sleeve 30, completes all of the operations necessary to effect a connection.

Preferably the arcuate slot 41 in the boss 29 is of sufficiently great extent that the blocking of rotation of the barrel results from a bottoming or abutment of the locking flanges 22 against the walls 11, 12 of the channel rather than impingement of the screw 36 against the terminal end of the slot 41.

It will be further appreciated that, due to the resilient nature of the material of which the electrical conductors 34, 34 are fabricated, a secure electrical connection between the contact ears 23, 23 and the conduits 17 and 18 is assured, not-withstanding the rotated position of the conduits relative to the track may vary by a few degrees.

As will be apparent to those skilled in the art, variations may be made in the specific constructions of the illustrated embodiment without departing from the spirit of the invention and, accordingly, the invention is to be broadly construed within the scope of the appended claims.