ELECTRICAL ADAPTOR

Abstract: An electrical adaptor is arranged to receive an electrical plug of one standard type and to be inserted into sockets of other standard types. There are a plurality of pins which may be selectively extended from the adaptor to conform with various standard sockets. The adaptor is provided with external earth contacts, for instance for co-operation with European socket earth contacts, and has a sprung cover which conceals the earth contacts and may be retracted for use.

Description: ELECTRICAL ADAPTOR The present invention relates to electrical adaptors which allow an electrical appliance connected to a conventional plug according to one standard to be connected to an electrical supply outlet of a type according to a different standard. It is known, for instance in GB-B-2097202, now assigned to the present applicant, to provide such an adaptor. However, the adaptor described in that document has a complex arrangement of connectors within the adaptor for providing earth connections. Also, the connections for European style sockets "wiping earth" contacts are provided on the outer surface of the adaptor which gives an unsightly appearance. In general terms the present invention provides an adaptor as described above having a simplified earthing arrangement and in which all of the connections need only be exposed when required for use. In particular, the present invention provides an electrical adaptor comprising a plurality of socket contacts arranged to receive an electrical plug, a plurality of pins adapted to be selectively extended through an end surface of said adaptor in a plurality of configurations, each of said pin configurations being suitable for insertion into and connection with a respective standard electrical socket, and means within the adaptor arranged to make appropriate live and neutral connections between a plug inserted into said socket contacts and the pins when in position for insertion into an electrical socket; the adaptor further comprising external earth contacts on a side surface of the adaptor arranged to make earth contact with an electrical socket, a cover arranged to conceal said earth contacts when in a first position and to expose said earth contacts when in a SUBSTITUTE SHEET second position and resilient biasing means arranged to urge said cover into said first position. In order that the present invention may be better understood a preferred embodiment thereof will be described by way of example, with reference to the accompanying drawings, in which: Figures la and lb show two perspective views of the preferred embodiment; Figure 2 shows the rear end of the adaptor with a selector plate removed; Figure 3 illustrates one of the pins incorporated in the preferred embodiment; Figure 4 is a view corresponding to Figure 2 but with the selector plate in position; Figure 5 shows ' a perspective view corresponding to Figure lb with- a cowling of the adaptor retracted; Figure 6 is a sectional view through the preferred embodiment; and Figure 7 shows the earthing connections in detail. The electrical adaptor according to the preferred embodiment of this invention allows an electrical appliance having a UK standard 13 amp 3-pin .plug to be connected to electrical supply outlets of other standard types, referred to herein as European style sockets and US style sockets. In particular the adaptor causes the earth connection in such sockets, if present, to be connected to the earth pin of the plug, in addition to providing the live and neutral connec¬ tions necessary for the functioning of the appliance. • However, the invention is also applicable to adaptors designed to receive another standard configuration plug and to be connected to other standard configuration sockets. Figures la and lb show two views of the preferred embodiment in its closed position. The adaptor 1 may be described as having a tapered shape with two ends, referred to as the front and rear. At the front of adaptor 1 is a circular front plate 2 having therein three rectangular holes 3 in a configuration corresponding to the pins of UK standard 13 amp 3-pin plug. The adaptor 1 comprises a main body portion 5 immediately behind front plate 2 and a cowling 6. The outer surfaces of main body 5 and cowling 6 are contiguous when the adaptor is in its closed position and define a shape which has both flat portions and curved portions as shown. The rear end of cowling 6 is planar and has a circular hole therein in which is a rotatable selector plate 7 and the end of pin housing 8, which are substantially coplanar with the end of cowling 6. In use, a standard 13 amp plug is inserted into holes 3 in front plate 2 and selected pins are extended from within pin housing 8 through selector plate 7 in either the European standard configuration or that of the US depending on the rotational position of the selector plate. The connections within the adaptor behind front plate 2 are conventional and are not shown or described in detail. In summary a metal clip is provided behind each of holes 3 into which a corresponding one of the pins of the inserted plug fits. There is also provided a terminal plate for each of the live and neutral connections. In the preferred embodiment each clip and respective terminal plate is formed as a one piece unit, although the adaptor may equally be constructed with each clip being mounted on a respective terminal plate. The earth connection will be described later. Figure 2 illustrates the rear end of pin housing 8 with selector plate 7 removed. At the end of pin housing 8 two metal connection plates 9 and 10 are mounted having respective screw holes 11 and 12 therein. A screw passing through the terminal plate on which the neutral connection clip in the front end of the adaptor is mounted passes through the length of the adaptor and into the screw hole 11. This serves both the purpose of physically securing connection plate 9 and the neutral terminal plate and that of providing an electrical connection between these two parts. The terminal plate on which the live connection clip is mounted and connection plate 10 are similarly connected by way of a screw in hole 12. Connection plates 9 and 10 also have therein round threaded holes 13 and 14 respectively. Holes 13 and 14 are of a size to allow round pins (not shown) of appropriate dimensions to fit a standard European style socket to pass through. Such pins are provided in adaptor 1 and each have a threaded end portion. When not in use the pins are positioned in cavities behind holes 13 and 14 within pin housing 8. When required the pins are caused to slide through holes 13 and 14 and the threaded end portions are screwed into the thread around respective holes 13 and 14. This ensures electrical connection between the pins and the connection plates 9 and 10 and hence to the respective connection clips in the front end of adaptor 1. Connection plates 9 and 10 further have therein slot shaped holes 15 and 16. Holes 15 and 16 are of a size to allow flat cross-section pins (not shown in ^ Figure 2) of appropriate dimensions to fit a standard US style socket to pass through. Such pins are provided in adaptor 1 and when not in use are positioned in cavities behind holes 15 and 16 within pin housing " 8. When required the pins are caused to slide through holes 15 and 16. Figure 3 illustrates such a US style pin. The pin comprises the flat cross-section portion 30 which has a narrower end portion 31. Over end portion 31 is positioned movable plate 32 and spring 33 which are retained by fixed plate 34. In order to fix the pin in position, main portion 30 is caused to slide through hole 15 or 16 and movable plate 30 rests against the inside of the connection plate. The pin is then pulled further through the hole, compressing spring 33, and is turned. The biasing of the spring then fixes the pin in position and ensures electrical connection between the pin and the connection plate. The pins in holes 15 and 16 may either be positioned parallel to each other for use with US sockets, or may be angled with respect to each other for use in some southern hemisphere countries. Figure 4 illustrates the rear end of pin housing 8 with selector plate 7 in position. Selector plate 7 is rotatably mounted by way of a center spigot 17 in hole 18. Selector plate 7 has holes 19 and 20 therein and, as will be apparent from a comparison between Figures 2 and 4, by appropriate rotation of selector plate 7, either the European style pins or the US style pins may be withdrawn through holes 19 and 20, but not both types together. Also the plate 7 may prevent the withdrawal of any of the pins, for instance when in the position shown in Figure 4. The foregoing has described how the adaptor according to the preferred embodiment functions with regard to providing the live and neutral connections for the appliance plugged into the front end of the adaptor. The following describes how this adaptor also provides an earth connection for the appliance. In the case of the US configuration, earthing, if provided, is via a round pin in addition to the two flat pins described above. In the preferred embodiment this is provided by a pin provided in hole 21 in the rear end of pin housing 8. The US earthing pin is similar to the European style live and neutral pins in that it is round and has a threaded end portion. When rur SHΞEΓ not in use the US earth pin is positioned in a cavity in pin housing 8 behind hole 21. When required it is caused to slide through hole 21 and there is provided within pin housing 8, as described below, an earth connection.having a threaded portion into which the threaded end portion of the earth pin screws. In the case of the European configuration, earthing may be provided in two ways. Firstly, there may be provided in the supply outlet a round earth pin, " in addition to the two sockets adapted to accept the live and neutral pins. This roun earth pin is accepted by a socket in what is conventionally known as the plug. In the present embodiment such a socket is provided within pin housing 8 behind hole 22. Secondly, in the European configuration earthing may be provided by way of a "wiping earth" connection. The earth contacts are provided on the outer surface of the plug which fits a recessed socket with appropriate connections. In the present " embodiment wiping earth contacts 23 are provided. To allow connection to sockets of the type mentioned above cowling 6 is retracted into main body 5 as shown in Figure 5. This exposes pin housing 8 with wiping earth contacts 23 running longitudinally along its outer surface. Pin housing 8 also has longitudinal ribs 24 to conform to the standard sockets. The exposed portion of pin housing 8 is inserted into such a recessed socket to make the earth connection via the wiping earth contacts 23. Figure 6 is a schematic sectional view through the adaptor according to the preferred embodiment and illustrated in Figure 1, but with some detailed omitted- for clarity. Figure 6 shows main body portion 5 with front plate 2, pin housing 8 with selector plate 7 and cowling 6. Cowling 6 is held in its normal position by way of spring 25 and rib 26 on main body 5 acting on rib 27 on cowling 6. When a force is applied to the left » •» * ■ **,*_, kli t w- tlή fej-L-Ti^iST hand end of cowling 6, as shown in Figure 6, spring 25 compresses and cowling 6 retracts inside main body 5, exposing pin housing 8. When the force is removed cowling 6 returns to its normal position under the action of spring 25. Figure 6 also shows some of the earth connections within the adaptor. Behind one of holes 3 in front plate 2 is positioned earth clip 40 which receives and makes connection with the earth pin of a plug inserted into the adaptor. Clip 40 is connected to earth strap 41. Earth strap 41 is essentially a flat strip of metal bent into a "U" shape as shown. The two arms of earth strap 41 form the wiping earth contacts 23. Figure 7 shows further details of the earth connections within the adaptor. Figure 7 illustrates the earth connections without any details of the adaptor but it is apparent from comparison with the other figures, especially Figure 6, how the earth connections are incorporated into the adaptor. Figure 7a shows earth strap 41 and clip 40 and in addition shows earthing sleeve 42 and earth socket 43. Socket 43 is provided in the same plane as the U-shape of strap 41 and is connected thereto. Socket 43 is arranged to be within pin housing 8 behind hole 22 whereby to receive the earth pin in the first mentioned European earthing arrangement. Earthing sleeve 42 is a hollow metal cylinder and is provided out of the plane of the U-shape of strap 41 and is arranged to be within pin housing 8 behind hole 21. Sleeve 42 is mounted on strap 41 as shown in Figure 7b, which is a view of the earthing arrangement in direction "A" in Figure 7a. The US earthing pin described above is provided within sleeve 42, which has, at its end furthest from clip 40, a threaded portion on its inner surface into which the threaded end of the US earth pin may be screwed when in its withdrawn position. Thus by way of the connections within the adaptor as shown in Figure 7, an earth-connection may be made between the earth pin of a plug inserted into front plate 2 and the sockets of either European or US configuration. Referring to Figures 2 and 4 it is apparent that cut-out portion 28 in selector plate 7 allows access to hole 22 when the European pin configuration is selected and allows the US earthing pin to be withdrawn from hole 21 when the US pin configuration is selected. It will be noted from Figures 1 and 6 that slots 45 are provided in the face of front plate 2. These slots enable projections 46 to be moulded. The projections 46 are received in corresponding grooves in the main body 5 and allow the front plate to be snapped to the main body during assembly.

Claims: CLAIMS : 1. An electrical adaptor comprising a plurality of socket contacts arranged to receive an electrical plug, a plurality of pins adapted to be selectively extended through an end surface of said adaptor in a plurality of configurations, each of said pin configurations being suitable for insertion into and connection with a respective standard electrical socket, and means within the adaptor arranged to make appropriate live and neutral connections between a plug inserted into said socket contacts and the pins when in position for insertion into an electrical socket; the adaptor further comprising external earth contacts on a side surface of the adaptor arranged to make earth contact with an electrical socket, a cover arranged to conceal said earth contacts when in a first position and to expose said earth contacts when in a second position and resilient biasing means arranged to urge said cover into said first position. 2. An electrical adaptor according to claim 1 having first and second substantially parallel, flat end surfaces, said plurality of pins being extendible through said first end surface and said plurality of socket contacts being arranged behind apertures in said second end surface whereby to receive pins of an electrical plug inserted through said apertures. 3. An electrical adaptor according to claim 2 in which said first end surface has a smaller area that said second end surface and the adaptor has a tapered shape when said cover is in said first position. SUBSTITUTESHEET 4. An electrical adaptor according to claim 1, 2 or 3 in which said resilient biasing means is a helical spring. " 5. An electrical adaptor according to any of claims 1-4 in which one of said plurality of pin configurations is arranged to co-operate with a standard European-style socket. 6. An electrical adaptor according to claim 5 in which said external earth contacts are arranged to co¬ operate with earth contacts in a standard European-sytle socket. 7. An electrical adaptor according to any of claim 1-6 in which one of said plurality of pin configurations is arranged to co-operate with a standard North American socket. 8. An electrical adaptor according to any preceding claim arranged to receive a UK standard 13 amp 3 pin plug.

Inventors: WRIGHT PHILIP, WRIGHT, PHILIP
Applicants: ROSS GROUP PLC
Application year: 1992
Main classification: H01R31
IPC codes: H01R31