GB2273825A

GB2273825A - Electric mains branching adaptor

Info

Publication number: GB2273825A
Application number: GB9226658A
Authority: GB
Inventors: Cheok Choo Lim
Original assignee: NCE ELECTRICAL
Current assignee: NCE ELECTRICAL
Priority date: 1992-12-22
Filing date: 1992-12-22
Publication date: 1994-06-29
Anticipated expiration: 2012-12-22
Also published as: GB9512758D0; GB2288926A; MY133737A; MY110357A; GB9226658D0; GB2273825B; CN1069788C; CN1158016A; GB2288926B; CN1089400A

Abstract

An electric mains adaptor, for example a three-way adaptor in a box-shaped housing from which projects a set of input pins (not shown) for insertion into a mains socket, preferably has a rearwardly-projecting central portion of the housing, so as to provide a gap between the remainder of the adaptor housing and the mains supply socket into which the adaptor is inserted. Each live and neutral input pin is connected to all corresponding socket contacts by means of a conductive link bar (21), which may be a push fit with the corresponding input terminal (16N, 16L). The output sockets (29N, 29L, 31N, 31L, 34N, 34L) are preferably formed integrally in the link bars (21). An internal support (18), in this example a plastics plate, supports the link bars (21), and may be used as a pre-assembly during manufacture. The earth link (15E) may be supported by the adaptor body separately from the support (21). <IMAGE>

Description

Electric Mains Adaptor This invention relates to an electric mains adaptor, that is to a unit for the selective connection of a number of electric loads to a single electric supply.

The invention is particularly, but not exclusively, useful as a box type adaptor with two or more sockets connected electrically in parallel to a single set of input pins for insertion into a supply socket.

Conventional adaptors are of a relatively complex structure, dictated partly by the need for adequate electrical insulation between for example the live, neutral and earth conductors and their associated conductive paths. In the case of an adaptor for the United Kingdom where the mains supply is 13 amps and 250 volts A.C., the relevant standards which must be met are defined by SS246, MS1199 and BS1363/3. Complexity in the structure leads to high cost both of the components and as a result of the complex manufacturing steps.

Accordingly, the invention firstly provides an electric mains adaptor having an input set of mutually-insulated terminals connected in parallel to each of a plurality of output sets of corresponding mutually-insulated terminals, comprising, for each of at least one of the input terminals, a single conductive internal link bar interconnecting that input terminal with both or all of the corresponding output terminals, the or each link bar being a push fit with the corresponding input terminal.

A method according to the invention of manufacturing such an electric mains adaptor comprises forming as a pre-assembly the input set of terminals in part of a housing of the adaptor, then push-fitting the or each link bar onto the corresponding input terminal or terminals, and then closing the structure with another part of the adaptor housing.

Secondly, the invention provides an electric mains adaptor having an input set of mutually-insulated terminals connected in parallel to each of a plurality of output sets of corresponding mutually-insulated terminals, comprising, for each of at least one of the input terminals, a single conductive internal link bar connected electrically to the input terminal and having integrally-formed terminals constituting both or all of the corresponding output terminals.

Thirdly, the invention provides an electric mains adaptor having an input set of mutually-insulated terminals connected in parallel to each of a plurality of output sets of corresponding mutually-insulated terminals, comprising a housing and an internal, electrically-insulative support structure supporting mutually-insulated conductive link bars which interconnect internally of the housing the corresponding input and output terminals, the support structure being a push fit within the housing during assembly of the adaptor.

A method of manufacturing an electric mains adaptor of the type described immediately above comprises forming as a first pre-assembly the input set of terminals in part of the housing and forming as a second pre-assembly the support structure and the link bars thereon, push-fitting the first and second pre-assemblies together so as electrically to connect the input terminals to their link bars, and then fitting the remaining part of the housing to complete the adaptor.

Irrespective of the internal structure of the electric mains adaptor, it is a further object of the invention to make the overall structure as compact as possible, and moreover to facilitate the removal of the adaptor from a socket into which it is inserted, in use; for example, to facilitate its removal from a mains socket flush with a vertical wall.Accordingly, the invention also provides an electric mains adaptor having a box-shaped housing from the rear face of which projects a set of input pins for insertion into a mains socket, connected electrically in parallel to respective terminals of each of a plurality of output sockets in side and front faces of the housing, the rear face being planar but having a central portion projecting normally of the plane and having a planar base parallel to the plane, the input pins extending normally from the central portion, whereby in use the planar face of the central portion abuts a mains supply socket to provide a clearance between the mains supply socket and the rear edges of the side faces of the housing.

In order that the invention may be better understood, one example will now be described in greater detail, by way of example only, with reference to the accompanying drawings, in which Figure 1 is a perspective view of an electric mains adaptor from the rear and from the left-hand side; Figure 2 is a perspective view of the adaptor of Figure 1, from the front and left-hand side; and Figure 3 is an exploded perspective view from the left-hand side showing part of the interior of the adaptor.

An electric mains adaptor includes a hollow housing consisting of a rear portion 1 and a front portion 2 which mate and are screwed together through a set of four bores 3. The portions 1, 2 are one-piece plastics mouldings of electrically insulative material, resistant to impact, in accordance with the relevant standards required.

The rear of the adaptor consists of a planar face 1R from which projects centrally an extension 8 of the housing, which extension has a parallel planar face 1P, generally square with rounded corners. Pins 4E, 4L and 4N are embedded in the projection 8, constituting the conventional earth, live and neutral pins for insertion into a mains socket complying with United Ringdom standards. Adjacent the earth pin 4E is a plastics-moulded fuse holder 5 including a plate flush with the planar surface 1P of the housing extension 8.

As shown more clearly in Figure 3, a conventional 13 amp fuse F is held within the fuse holder 5; as shown in Figure 2, recesses on either side of the holder 5 allow it to be gripped and removed for replacement of the fuse in use.

As shown in Figures 1 and 2, the adaptor is a three-way adaptor, providing three mains sockets on respective faces of the box housing. On the top side face, openings 6EA, 6LA and 6NA are provided in the housing for guiding the earth, live and neutral pins of a conventional mains plug, to mate with internal electric sockets, described below with reference to Figure 3.

Corresponding sets of openings 6NB, 6EB and 6LB are provided on the front face; and corresponding openings 6EC, 6LC and 6NC are provided on the underside face.

With reference to Figures 2 and 3, a red filter plate of plastics material 7 is push fitted into an opening in the front face of the housing 2. Although not shown in the drawing, a neon lamp is mounted between projections from the inner surface of portion 2 of the housing, so as to transmit light through the filter plate 7 whenever the adaptor is live. This feature is optional: in an alternative example, the neon light and filter plate are omitted. In this example, again not shown in the drawings, the neon lamp is connected by insulated wires, with a series resistor, to coil spring contacts mounted in projecting tubular formations on the inner face of the housing portion 2. The coil spring contacts, when the adaptor is assembled, engage and make electrical contact with upper flat surfaces 30N and 30L of link bars 27N and 27L, to be described below in greater detail.In this way, the lamp is connected electrically in parallel with the live and neutral terminals.

With reference to Figure 3, insulative, spring-biased shutters 10 slide within a socket 14A adjacent the top side of the housing and a corresponding socket 14C adjacent the underside of the housing. These shutters are conventional, and are biased by springs 12 in recesses 13 to a position where the shutters close the openings for the live and neutral pins through the housing wall. The shutters are generally T-shaped, and include a cam portion 11 which obstructs the corresponding opening for the earth pin. In use, as a plug is inserted into the corresponding socket, the earth pin enters the opening 6EA or 6EC, engages the shutter portion L, slides along the cam surface and forces the shutter to slide open against the bias of the spring 12. With continued insertion, the shutter opens completely, to allow entry of the live and neutral pins. Although not shown in the drawings, a corresponding shutter is provided on the inside surface of the front face of the housing, to protect live and neutral openings 6LB and 6NB on that face.

As shown on the left-hand side of Figure 3 which shows the interior of the rear portion of the housing, bars 15N, 15L and 15E are riveted at one point only to the corresponding neutral, live and earth pins 4N, 4L and 4E. In the drawing, the rivets are depicted as double circles. The neutral bar 15N extends in the plane of the rear face 1R, and then is bent through 90 to extend inwardly of the housing, terminating at a bent-back portion 16N which is resiliently-deformable for engaging a correspondingly resiliently-deformable clip portion 33N of the link bar 27N. The live bar 15L extends in the plane of the rear face 1R of the housing to a resilient clip for the fuse F, whose other end is held by a resilient clip of a separate L-shaped bar 16L. The link bar 16L has one limb adjacent the clip and extending parallel to the plane of the rear face 1R of the housing.It is then bent through 90 , to extend into the interior of the housing, to terminate in the same way as the neutral bar, with a resiliently-deformable contact for engaging a corresponding resiliently-deformable clip portion 33L of the live link bar 27L.

The earth bar 15E terminates at the lower end with a clip 16EC which is the earth socket at the underside of the adaptor. At the opposite end, it terminates with earth socket 16EA and, after a transverse extension limb, with earth socket 16EB. The extension of earth bar 15E extends through the interior of the housing, and through an insulated opening 18 in a support plate 17 to be described below so that the earth socket 16EB lies adjacent the opening 6EB through the front face of the adaptor.

Two electrically conductive link bars 27N and 27L provide the internal electrical connections in parallel to each of the three outlets for live and neutral. They are supported on a specially-moulded electrically-insulative support plate 17 which is generally rectangular with its longer edges flush with the inner surface of the housing. The support plate 17 has four rectangular apertures: a pair of apertures 19N and 19L allow the clips 33N and 33L respectively of the link bars to engage with the neutral and live contacts; and a pair of apertures 20N and 20L provide for a deeper seating for neutral and live sockets 31N and 31L adjacent openings 6NB and 6LB respectively in the front face of the adaptor. A notch 18, as mentioned above, allows the earth bar 15E to extend from the rear to the front of the adaptor without contacting the live or neutral conductors.

The support plate 17 is formed with several wall portions projecting towards the front normally, which serve to guide and retain the neutral and live link bars 27L, 27N. These projections consist of walls 21, 22, 23, 24 and 25, all parallel to one another and arranged symmetrically about a central plane parallel to the side walls of the housing. In a transverse plane, projecting walls 26 provide further guidance for the neutral and live sockets 31N, 31L.

The neutral and live link bars 27N, 27L are generally symmetrical about the central plane parallel to the side walls, but not entirely symmetrical, to allow electrical insulation across an air gap at the point where the bars cross over one another. Further, planar portions 30N, 30L, mentioned above, are deliberately given different shapes to enable the different bars to be distinguished visually with greater ease.

The live link bar 27L will now be described, in detail; the neutral link bar corresponds. The bar is formed from plate metal, stamped so as to form a shaped blank, and then bent to form the required configuration. From the lower end, the bar starts with a resiliently deformable, U-shaped socket 29L, lying adjacent the opening 6LC in the underside of the adaptor, for receiving the live pin of an external plug. From this extends transversely and diagonally a crossing limb 28L, connected to a principal wall portion 32L, extending parallel to the side walls of the adaptor housing over a major part of the height of the adaptor. The planar portion 30L for contacting the lamp terminal, and a U-shaped socket 31L, lying adjacent the opening 6LB in the front face of the adaptor, are connected to the principal wall 32L.Above this, the U-shaped clip 33L extends transversely from the principal wall 32L, and, as previously described, makes a push fit with the contact 16L. Above this, at the opposite end of the principal wall 32L, extends transversely a further U-shaped socket terminal 34L, adjacent the opening 6LA in the top surface of the adaptor housing.

The configuration described above makes the adaptor particularly simple to assemble. The rear portion 1 of the housing is formed with the extending pins 4E, 4L and 4N, and is pre-assembled with the fuse F and fuse holder 5; the shutters 10 and corresponding springs 12 are slotted into place in this pre-assembly. In a separate location, the support plate 17 and the two link bars 27N, 27L are formed as a second pre-assembly.

Separately again, the front portion 2 of the housing is formed with the filter 7, if required, and the shutter 10 and corresponding spring 12 (not shown) are located on the inner surface, as a pre-assembly. Where the filter 7 is provided, the lamp and its associated terminals are also inserted with a push fit into this pre-assembly.

The support plate 17 pre-assembly is then pushed over the contacts 16N, 16L with a push fit, whilst guiding the edges of the support plate within the rear portion 1 of the housing. Finally, the adaptor is closed by connecting the front pre-assembly, securing the connection by means of the four screws (not shown).

With the use of the link bars as described, no riveting is required - except for the connection of the pins 4E, 4L, 4N to their respective terminals. This makes the assembly process easier, faster and simpler, and also makes the electrical connections more secure, with greater mechanical support. The assembled adaptor does not rattle. Further, the lack of riveting makes the internal dimensions more accurate, because tolerances can be improved. Further still, the support plate 17 which supports the two link bars simplifies the assembly process and also allows the overall weight of the assembly to be lower than conventional adaptors.

The projection 8 has two important functions. Firstly, it provides for a gap between a mains socket and the rear edges of the side walls, when the adaptor is inserted fully into the socket, to allow it more readily to be pulled from the socket. Secondly, it reduces the volume of the adaptor and its weight, in comparison with an adaptor whose rear wall is entirely flat.

Whilst the invention has been illustrated by means of a three-way box-shaped adaptor, it will be understood that the invention is more widely applicable. In particular, aspects of the invention may be applied to a multi-way adaptor of the type which rests on the floor and is connected via a flexible cable to a supply plug. The principles of providing the internal support plate, and of providing a link bar with a push fit, are widely applicable to electrical adaptors.

Claims

Claims:

1. An electric mains adaptor having an input set of mutually-insulated terminals connected in parallel to each of a plurality of output sets of corresponding mutually-insulated terminals, comprising, for each of at least one of the input terminals, a single conductive internal link bar interconnecting that input terminal with both or all of the corresponding output terminals, the or each link bar being a push fit with the corresponding input terminal.

2. An adaptor according to Claim 1, in which the or each link bar is so shaped as to constitute the output terminal.

3. An adaptor according to Claim 2, in which the output terminals are female, and in which the or each link bar is formed as a single piece of sheet metal folded to define a resiliently-deformable clip for the push fit with the input terminal, and resiliently-deformable sockets for receiving mains plug pins.

4. An electric mains adaptor having an input set of mutually-insulated terminals connected in parallel to each of a plurality of output sets of corresponding mutually-insulated terminals, comprising, for each of at least one of the input terminals, a single conductive internal link bar connected electrically to the input terminal and having integrally-formed terminals constituting both or all of the corresponding output terminals.

5. An adaptor according to Claim 4, in which the output terminals are female sockets for receiving mains plug pins.

6. An adaptor according to Claim 5, in which the or each link bar is formed as a single piece of sheet metal folded to define the sockets which are resiliently deformable.

7. An electric mains adaptor having an input set of mutually-insulated terminals connected in parallel to each of a plurality of output sets of corresponding mutually-insulated terminals, comprising a housing and an internal, electrically-insulative support structure supporting mutually-insulated conductive link bars which interconnect internally of the housing the corresponding input and output terminals, the support structure being a push fit within the housing during assembly of the adaptor.

8. An adaptor according to Claim 7, in which the support structure is generally planar but has integrally-formed projections for retaining the link bars with a push fit and extending generally parallel to its plane.

9. An adaptor according to Claim 8, in which two link bars are disposed on the same face of the support structure generally parallel and adjacent one another except for transverse extensions of the link bars which cross over one another and are spaced, normally of their plane, to ensure mutual electrical insulation at the cross-over.

10. An adaptor according to Claim 9, in which each link bar has three integrally-formed resiliently-deformable sockets constituting the output terminals, one such socket for receiving a mains plug pin normally of the plane of the support structure, and two such sockets at respective ends of the support structure for receiving mains plug pins parallel to the said plane, one of which end sockets is defined by the end of the said extension of the link bar.

11. A method of manufacturing an electric mains adaptor according to Claim 1, comprising forming as a pre-assembly the input set of terminals in part of a housing of the adaptor, then push-fitting the or each link bar onto the corresponding input terminal or terminals, and then closing the structure with another part of the adaptor housing.

12. A method of manufacturing an electric mains adaptor according to Claim 7, comprising forming as a first pre-assembly the input set of terminals in part of the housing and forming as a second pre-assembly the support structure and the link bars thereon, push-fitting the first and second pre-assemblies together so as electrically to connect the input terminals to their link bars, and then fitting the remaining part of the housing to complete the adaptor.

13. An electric mains adaptor having a box-shaped housing from the rear face of which projects a set of input pins for insertion into a mains socket, connected electrically in parallel to respective terminals of each of a plurality of output sockets in side and front faces of the housing, the rear face being planar but having a central portion projecting normally of the plane and having a planar base parallel to the plane, the input pins extending normally from the central portion, whereby in use the planar face of the central portion abuts a mains supply socket to provide a clearance between the mains supply socket and the rear edges of the side faces of the housing.

14. An electric mains adaptor, substantially as described herein with reference to the accompanying drawings.

15. A method of assembling the components of an electric mains adaptor, substantially as described herein with reference to the accompanying drawings.