GB2170065A - Electrical outlet connection systems - Google Patents

Abstract

An electrical connection system has a plug (10) with pins (12) and a socket outlet (30) with apertures (32) to take the pins (12) and contacts with which the pins make electrical contact only as a result of relative movement of the units after first entry of the pins (12) into the apertures (32), and a switching provision dependent on moving the pins (12) into and out of electrical contact with the contacts (30). The provision may comprise resilient non-conductive arms with detents 50A, 52A for locating in apertures (44) in pins (12) to hold the plug between entry and contact-making positions of the pins (12). <IMAGE>

Description

SPECIFICATION Electrical outlet connection systems Description The invention relates to electrical outlet connection systems particularly in relation to mains electrical wiring systems of a plug and socket type.

Our British patent specification no. 2139433 discloses a plug-and-socket system in which the plug is first entrant into the socket and then has to be moved rectilinearly to complete electrical connection between internal socket contacts and external plug pins. As so disclosed, the socket contacts are safely shielded, being displaced from plug pin entry provisions, such plug pins having end extensions in the direction of rectilinear movement to serve for electrical connection purposes.

It is, of course, further the case that a useful prevention of separation of the plug and socket without electrical disconnection of respective pins and contacts does or can result, such actually being provided via a further plug pin or pins usually an earth pin and a spare pin or projection.

In our development work through models and prototypes towards commercial production products, it has become increasingly evident that there is a useful possibility of using the aforesaid rectilinear movement effectively for switching purposes, and it is in connection with and arising therefrom that we make the further proposals hereof concerning switching provisions.

Basic to such specific proposals is, of course, ensuring that plug pin to socket contact clearances are or become after or during the aforesaid rectilinear movement sufficient to satisfy regulations and requirements applicable to switch contacts of mains wiring systems, and it is specifically proposed for the purposes of this invention that such be assured, i.e. achieved purposely by appropriate detail design.

It is, of course, appreciated that, for the purposes hereof, the relative plug/socket movement could be other than rectilinear between plug entry and achievement of electrical connection, for example rotary.

According to this invention, there is provided an electrical connection system comprising a first unit (plug) with pins and a second unit (socket) with apertures to take the pins and contacts with which the pins make electrical contact only as a result of relative movement of the units after first entry of the pins into the apertures, wherein switching provision is made dependent on moving said pins and out of electrical contact with said contacts.

Moreover, and in a particular aspect of this invention, it is proposed that for the switching provision, the units cooperate to define mutually electrically safe contact-making (ON) and non-contact making (OFF) positions spaced in the direction of said relative movement and to provide opposition to movement between said positions. Such opposition can be from mechanical means whereby movement of the plug pins within the socket and towards the contacts of the latter shall be subject to resistance requiring some degree of force to overcome. Then, movement of the plug to release electrical connection of its pins with the socket contacts and into or past the mechanical resistance means will manifestly require overcoming of the latter in order to re-establish said electrical connection.

It is the case that the mechanical resistance means can be simply embodied via cooperation of a plug pin with a profiled spring lead or a ball catch device or other suitable detent system so that the pin or pins concerned can traverse the same in both directions, and it may be advantageous for the same to require different, perhaps lesser, force than release of actual electrical connection.At least then, such mechanical resistance means can be disposed or at least operative medially of the movement of the pins between physical engagement/disengagement ralative to the socket and electrical connection positions, and it may be preferred to provide a second mechanical resistance between that first mentioned and the engagement/disengagement or otherwise assume a latching or gripping condition between the aforesaid positions so as to have a stable OFF state in which the plug and socket are not readily disengageable, whether by virtue of the relationship of the plug pins to the socket entries or by simply gripping of the plug pins. In the latter case a simple light grip in spring means at plug pin entry to the socket may suffice.

It will be evident that the above references to a plug pin or pins in relation to cooperating with the mechanical resistance means can apply to an earch pin rather than either or both of live and neutral pins, even equally well be achieved via any protrusion from the plug body and any corresponding entry of the socket body.

Thus, for example, the operative protrusion can be an earth pin, perhaps with the live and/or neutral pins employed in click-action latching at electrical connection or vice versa or with the earth pin providing both. Contrariwise, the operative protrusion may be other than any of earth, live and neutral pins and whether or not it or any one or more of the latter provide electrical connection latching as mentioned above for what is shown in the aforesaid specification. In fact, the further protrusion provision is seen as being of particular relevance in relation to the plug-and-socket system shown in that aforementioned specification, which has two spaced side-by-side L-shaped protruding live and neutral pins themselves between two relatively longitudinally spaced T-shaped or loop-type earth and other pins.Nonetheless other shapes of pins and other relative movement directions are plainly readily achieved, for example rotary with such pins at appropriate radial positions.

There is one particular application for this invention that allows taking especial advantage from the modularity also emphasised in our aforesaid British patent specification for inclusion of basic socket and/or plug units within bodies then constituting together particular desired electrical accessories, such as socket plates, ceiling roses, etc. Thus, plu ral sockets hereof may be provided in multi-gang socket plates, and/or adaptors of direct or trailing lead types, and, then, the provisions hereof allow each plug unit for association therewith to act as its own switch by simple bodily movement thereof on such socket plate or adaptor face.

Moreover, for the plugs and sockets of our aforesaid patent specification, where, for downward movement of the plug on a wall mounted socket to get electrical contact, the earth pin is uppermost and the other pin lowermost, the possibility arises of reversing the earth pin and other pin locations.

One specific implementation of this invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 7 is an internal plan view of a socket unit with its cover plate removed; Figure 2 is a plan view of the connection face of that socket unit; Figure 3 is a plan view of the connection face of a plug unit; Figure 4 is an end view of that plug unit; Figure 5 is a section of the centre line of Figure 3; Figure 6 is a combination of sections on lines X X of Figure 1, and on lines Y-Y of Figure 5 for physical connection/disconnection; and Figure 7 shows an application to a trailing lead multi-way adaptor.

In the drawings, a plug unit 10 has two laterally spaced medial L-shaped protruding contact pins 12, 14 for live and neutral. There are two further projections 16, 18 each shown of T-shape and one (16) actually serving as an earth pin, see screw clamp connector 20. There will, of course, be screw clamp connectors also for the pins 12, 14 (not shown). A screw 22 is shown for affixing the basic plug unit to an accessory cover, see dashed outline 24.

The contact pins 12, 14 and protrusions 16, 18 of the plug unit 10 will enter apertures 32, 34 and 36, 38 of a socket unit 30 and then be movable so that the bent-over leaves of the contact pins 12, 14 go under the edges 32A, 34A into live and neutral contacts 40, 42 of the socket and heads of the projections 16, 18 go under reduced width portions 36A, 38A of the apertures 36, 38. In doing so, projection 16 as an earth pin will engage earth contact 43 of the socket unit 30.

Further details of the plug and socket units 20 and 30 may be had from our copending application no. 8411530.

It will be appreciated that live and neutral connections between plug and socket units are made only after entry of plug pins and projections into the socket unit and relative movement of those units. Holes 44 are shown in the bent-over leaves of the live and neutral plug pins 12, 14 for click-action engagement with pips 46, 48 on the socket contacts 32, 34.

One way of implementing this invention utilises those holes 44, see Figure 6, and dashed in Figure 1, showing pairs of resilient insulating leaves 50, 52 (for the cover omitted from Figure 1) with pips 50, 52A to engage said holes 44 at a relative position of the plug and socket units that is prior to first making of live and neutral connections, actually immediately at entry of plug pins into socket apertures, i.e. at first physical engagement of plug and socket and prior to plug unit movement for electrical connection purposes.Manifestly, however the pips 50A, 52A could so engage during such plug movement, see further dashed lines 50A and for modification of the illustrated socket contact retainer, i.e. after the first physical disengagement position of the plug unit and the socket unit, i.e. whilst the heads of the T-shaped projections 16, 18 are still at least partially within the narrowed parts 36A, 38A of the apertures 36, 38 on the socket face, though it might be necessary to alter the size and geometry of the plug pins and/or socket openings to give adequate clearance in the OFF state.

Self-evidently, not only resistance to re-engagement of plug and socket contacts, but also latching is provided at a safe disengagement position so that the plug unit can be used effectively as a switch.

A typical application of this invention is indicated in Figure 7, which shows a trailing lead multi-way adaptor 60 having four in-line sockets 30A-30D all fed from an electrical cord 62 that may well carry a standard three-pin mains plug at its other end.

Only one (64A) of up to four associated plugs is shown, also wired by cord 66A for connection to circuits such as table lamps etc. A neon indicator is also shown at 68. It is foreseen that an alternative to the adaptor 60 would have an additional overall fuse, or simply replace that left-most socket (30A) with a carbridge fuse.

Reverting to the above plug and socket units 10, 30 as such, it should be evident that retention as at or mechanically equivalent to 44, 50 could be made relative to the earth pin 16 or the other projection 18, say via resilient means in the socket unit.

Turning to further alternatives, the switching provision of this invention is equally applicable to plugs and sockets with pins and apertures at radial spacings from relative rotation axes and normally requiring such rotation between a first physical en gagement/entry position and an electrical connection making position.

Claims (19)

1. An electrical connection system comprising a first unit (plug) with pins and a second unit (socket) with apertures to take the pins and contacts with which the pins make electrical contact only as a result of relative movement of the units after first entry of the pins into the apertures, wherein switching provision is made dependent on moving said pins into and out of electrical contact with said contacts.

2. An electrical connection system according to Claim 1, wherein, for the switching provision, the units cooperate to define mutually electrically safe contact-making (ON) and non-contact making (OFF) positions spaced in the direction of said relative movement and to provide opposition to movement between said positions.

3. An electrical connection system according to Claim 2, wherein said non-contact-making position is spaced from said contact-making position towards said first entry.

4. An electrical connection system according to Claim 3, wherein said non-contact-making position is at said first entry.

5. An electrical connection system according to Claim 3, wherein said non-contact-making position is between said contact-making position and said first entry.

6. An electrical connection system according to Claim 5, wherein, at said non-contact-making position, said units cooperate against relative separation.

7. An electrical connection system according to any one of Claims 2 to 6, wherein the opposition provision comprises mechanical means affording resistance to said movement between said positions.

8. An electrical connection system according to Claim 7, wherein the mechanical means opposes movement into said contact-making position.

9. An electrical connection system according to Claim 7, wherein the mechanical means opposes movement out of said contact-making position.

10. An electrical connection system according to Claim 7, 8 or 9, wherein the mechanical means is operative relative to at least one of earth, live and neutral pins.

11. An electrical connection system according to Claim 7, 8 or 9, wherein the mechanical means is operative relative to another projection from the first unit into the second unit.

12. An electrical connection system acording to Claim 10, wherein the mechanical means is operative relative to both live and neutral pins.

13. An electrical connection system according to any one of Claims 7 to 12, wherein the mechanical means is in the second unit.

14. An electrical connection system according to any one of Claims 7 to 13, wherein the mechanical means provides resilient pin or projection engagement.

15. An electrical connection system according to Claims 12 and 14, wherein the pins are of blade form and the resilient engagement is from opposite sides.

16. An electrical connection system according to Claim 14, wherein the resilient engagement involves pips of the mechanical means and an aperture in the pins.

17. An electrical connection system arranged and adapted to operate substantially as herein described with reference to and as shown in Figures 1 to 6 of the accompanying drawings.

18. A multi-way electrical outlet device of or for an electrical connection system as claimed in any preceding claim, comprising a plurality of said second units (sockets) in a common body or housing.

19. A multi-way electrical outlet device substantially as herein described with reference to and as shown in Figure 7 of the accompanying drawings.