Low Voltage Electrical Distribution System

This invention relates to a low voltage electrical distribution system. By "low voltage" is meant 50 volts or less.

It is an object of the invention to provide a low voltage electrical distribution system in which power can be tapped at any desired place over a considerable distance or surface area, for use for example in shop window display illumination.

According to the invention there is provided a low voltage electrical distribution system comprising a distribution bus and a jack plug, the distribution bus comprising two electrodes supplied or adapted to be supplied with low voltage electricity therebetween, at least one of the electrodes being in the form of a sheet providing a substantial number of alternate positions over one surface of the sheet for the jack plug to be plugged into the distribution bus at any selected one of said positions to make electrical contact with both electrodes.

FIG. 1 illustrates a low voltage electrical distribution system embodying the invention, showing a distribution bus and a jack plug, the sheets of the distribution bus being shown exploded;

FIG. 2 is a greatly enlarged perspective view of the jack plug of FIG. 1;

FIG. 3 is a sectional view illustrating the jack plug engaged with the distribution bus;

FIG. 4 is a partial view corresponding to FIG. 3 but showing the jack plug unclipped from the distribution bus;

FIG. 5 is an exploded perspective view of the jack plug;

FIGS. 6, 7, 8 and 9 illustrate modified distribution buses.

Referring to FIGS. 1 to 5 of the drawings, there is illustrated a low voltage electrical distribution system 10 which comprises a distribution bus 12 and a jack plug 14.

The distribution bus 12 is formed by a lamination of a front sheet electrode 16 and rear sheet electrode 18 of electrically conductive material (for example, copper or aluminium) separated by a sheet 20 of electrically insulating material (for example foamed plastic or foamed glass) and supplied or adapted to be supplied (by means not shown) with low voltage electricity, that is, 50 volts or less.

The jack plug 14 comprises an insulating holder 22 (in two halves 22/1 and 22/2) an electrical contact assembly 24, a generally disc-like member 26 and a rotatable thumb-wheel 28.

The insulating holder 22 comprises a generally cylindrical hub 30 (formed by hub halves 30/1 and 30/2) at the front end of which is a disc-like flange 32 formed by flange halves 32/1, 32/2. A hub 34, formed by hub halves 34/1, 34/2, projects forwardly of flange 32 and has a forwardly tapering frusto-conical portion 36 (parts 36/1, 36/2) behind which is a reduced diameter neck 38 (38/1, 38/2).

About two thirds along the hub 30 from the flange 32 is an external flange 40 (40/1, 40/2) and, just forwardly of that, internal flange portions 42.

The electrical contact assembly 24 comprises an electrical contact pin 44 and an electrical contact sleeve 46 which may be of brass. The pin 44 is slidingly received in the sleeve 46 and is electrically insulateld therefrom by an insulating sleeve 48. The pin 44 is cranked at 44a and its rearward end portion 44b carries a compression spring 50 and washer 52, acting between the cranked pin portion 44a and the internal hub flange portion 42 of the insulating holder 22, to bias the pin 44 forwardly of the holder 22, so that it makes good contact with the rear conductor sheet 18 (FIG. 3).

A crimped ferrule 54 electrically connects an insulation sheathed wire 56 in well known manner to pin portion 44b. A crimped ferrule 58 similarly connects another insulation sheathed wire 60 to a metal post or tab 62 which is integral with the contact sleeve 46. The contact sleeve 46 is longitudinally slit so as to be resilient for purposes of making good electrical contact with the front conductor sheet 16 (FIG. 3).

In order to make the jack plug 14 self-securing, it is adapted to clip itself to the distribution bus 12 by means of four clips 62 which clip into holes 64 in the front conductor sheet 16. These clips 62 are integral parts of the disc-like member 26, which is seated on the flange 32 of holder 22 and is keyed non-rotatably with holder 22 by conventional means not shown. The clips 62 are upstanding integral extensions of four spring arms 66 which extend around the periphery of disc-like member 26 and are themselves also integral parts thereof.

The rotatable member 28 is rotatably mounted on the front end of the insulating holder 22. More particularly, rotatable member 28 has a ring of inwardly bent spring clips 68 which engage the hub 34 behind the frusto-conical portion 36, their springiness enabling them to be pushed over the portion 36 on assembly.

The rotatable member 28 has four arcuate camming slots 70, through which the clips 62 extend. Each slot 70 has one, enlarged end 72 nearer to the central axis of rotation than the other end 74, which is angularly spaced from the first slot end 72 relative to the rotational axis. The natural (i.e. unstressed) positions of clips 62 and arms 66 is as shown in FIG. 5 (and also in FIG. 4), such that the clips 62 can be readily poked through the enlarged inner ends 72 of the slots 70 on assembly. When member 28 is rotated so that the clips 62 relatively slide in slots 70 to the outer ends 72, the clips 62 are cammed radially outwardly to the positions shown in FIG. 3. In these positions, being radially outwardly bent, as shown, the clips 62 engage the rear side of the front conductor sheet 16 as shown. The member 28 has a knurled rim 76.

In use, after the required position for the jack plug 14 on the distribution bus 12 has been chosen, the contact pin 44 is pushed through the appropriate hole 64 in the front conductor sheet 16 and through the insulating sheet 20 to make contact with the rear conductor sheet 18.

Simultaneously, the contact sleeve 46 enters the same hole 64 to make contact with the front conductor sheet 16. Also, the four clips 62 (in their inward positions, see FIGS. 4 and 5) enter four other holes 64.

Then the rotatable member 28 is rotated to cam the clips 62 outwardly to their FIG. 3 positions, to clip the jack plug 14 to the distribution bus 12.

The member 28 can be rotated the other way to unclip the jack plug 14 from the distribution bus 12, so that it can be withdrawn therefrom (possibly for repositioning).

The sleeve 46 is preferably chamfered at its front end to facilitate its insertion into the selected hole 64 in the front conductor sheet 16.

Referring to FIG. 6, a modified distribution bus 12a comprises a front sheet electrode 16a and rear sheet electrode 18a which are spaced apart over most of their surface areas but with no insulating material in the space, but only air. Sheet electrode 16a is stepped along one edge 80a and is provided with a lip 82a secured to sheet 18a via insulating material 84a. Away from the edge 80a the two sheets 16a and 18a are spaced apart by posts 86a, only one of which is shown. The sheet 18a is imperforate, like sheet 18 of distribution bus 12 (FIGS. 1, 3 and 4).

The modified distribution bus 12b of FIG. 7 is like the distribution bus 12a of FIG. 6, except that the second sheet electrode 18b, as well as the first sheet electrode 16b, is perforated with holes so that the jack plug (FIGS. 1-5) can be inserted into either sheet 16b or sheet 18b, that is to say, either side of the distribution bus 12b. The holes in sheet 16b are out of register with the holes in sheet 18b, in order that insertion of the jack plug into either of the two sheets will bring the central contact pin into contact with the metal of the other sheet.

Referring to FIG. 8, the modified distribution bus 12c is like distribution bus 12a except that the two sheets 16c and 18c are joined together along opposite side edges 80c1 and 80c2, with the result that the spacing of the sheets 16c and 18c does not require posts corresponding to posts 86a of FIG. 6.

Referring to FIG. 9, the sheet electrode 16d of distribution bus 12d is cylindrical and surrounds the second electrode, which is in the form of an elongate coaxial rod 18d, with means (not shown) supporting the electrode 18d coaxially within and electrically insulated from the electrode 16d.

In each of the distribution buses 12a to 12d of FIGS. 6-9, the two electrodes 16a-d and 18a-d are spaced apart across an air gap, rather than with insulation material in the gap, apart from wherein the electrodes 16a-c and 18a-c are joined together along one or both edges 80a-c. This reduces the cost of each distribution bus 12a-d as compared with the distribution bus 12 of FIG. 1, 3 and 4.