GB2464138A

GB2464138A - Electrical socket with shutters moving apart

Info

Publication number: GB2464138A
Application number: GB0818252A
Authority: GB
Inventors: Raymond Mazzullo; Brian Van Zyl
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-10-06
Filing date: 2008-10-06
Publication date: 2010-04-07
Also published as: GB0818252D0

Abstract

An electrical socket has first and second electrically conductive receptacles for receiving the pins of an electrical plug. Shutters 60 have operative positions in which they conceal said receptacles and prevent said plug pins from entering said receptacles and inoperative positions in which access to the receptacles by said plug pins is possible. A shutter activating element 68 is located between these shutters and is constrained to move rectilinearly between an operative position and an inoperative position, with links between the shutters and the element so that the shutters move with said element as the element moves between said two positions thereof. Guide means cause the shutters, whilst being displaced rectilinearly by said element, to simultaneously move apart from their operative positions to their inoperative positions, cam followers 62, 64 following guides 32, 34. The activating element may be operated by an earth pin or dummy pin (86, Fig 9) on the plug.

Description

SHUTFERED ELECTRICAL SOCKET

FIELD OF THE INVENTION

THIS INVENTION relates to a shuttered electrical socket for receiving the pins of an electrical plug.

BACKGROUND TO THE INVENTION

In the United States the most widely used electrical plug is a two pin plug with flat, spaced apart parallel blades.

Sockets having two parallel rectangular slots for receiving this type of plug are available. To enable the slots to be shuttered, a third dummy pin longer that the blades is provided. This enters an opening in the socket and acts on the shutter mechanism to move the shutters out of alignment with the rectangular slots and allow the flat blades to enter. Simple lateral movement of the shutters is all that is required to open the rectangular slots.

For higher amperages than those for which the above described plug is designed, a second type of plug is employed. This also has two spaced apart flat blades serving as plug pins. In this form, however, one blade is at right angles to the other.

Sockets for receiving these two types of plugs have one T-shaped opening and one rectangular opening. The T-shaped opening can receive either one of the two parallel blades of the low amperage plug (in the cross bar of the T) or the transverse blade of the higher amperage plug (in the upright of the T). The rectangular opening receives the flat blade constituting the other pin of both types of plugs.

Shuttering a socket with a T-shaped slot cannot be achieved by having shutters which lie parallel to one another and are simply moved apart. The movement that can be achieved is such that one of the two shutters will not clear the T-shaped slot and the flat blade that is intended to enter that slot will not be able to do so.

The present invention provides a socket which has a T-shaped slot and which is shuttered.

BRIEF DESCRIPTION OF THE INVENTION

According to the present invention there is provided an electrical socket comprising first and second electrically conductive receptacles for receiving the pins of an electrical plug, shutters having operative positions in which they conceal said receptacles and prevent said plug pins from entering said receptacles and inoperative positions in which access to the receptacles by said plug pins is possible, characterised by a shutter operating mechanism comprising a shutter activating element located between said shutters and which is constrained to move rectilinearly between an operative position and an inoperative position, links between the shutters and said element so that said shutters move with said element as the element moves between said two positions thereof, and guide means for said shutters, the guide means being such that the shutters, whilst being displaced rectilinearly by said element as the element moves from its operative position to its inoperative position, simultaneously move apart from their operative positions to their inoperative positions.

Said guide means can comprise guideways which are skew to the rectilinear path along which said element moves, said shutters including followers which are in the guideways.

Preferably there are two guideways for each shutter, and each shutter has a follower in each guideway, the guideways for each shutter been parallel to one another and spaced apart in the direction in which said element moves.

Said element can include two lugs which are in slots in the shutters, the lugs and shutters being free to move with respect to one another in the direction transverse to said direction in which said element moves.

Said element can further include a crossbar with elongate slots therein, two of said followers being in said slots and in said guideways and, in use, moving along the slots as the shutters move towards and away from one another during movement of said element.

Said socket can include a cover plate having two openings, there being one opening for each of said plug pins, and a third opening for a dummy plug pin, said dummy plug pin displacing said element from its operative position to its inoperative position as it enters said casing through said third opening.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings in which: Figure 1 is a plan view of the front face of a plug socket; Figure 2 is a pictorial view of the plug socket; Figure 3 is a plan view of the socket with a cover plate removed; Figure 4 is a view similar to that of Figure 3 but with parts of the shutter mechanism removed to show the underlying construction; Figure 5 is a pictorial view corresponding to Figure 3; Figure 6 is a pictorial view corresponding to Figure 4; Figure 7 is a side elevation of the socket with the cover plate removed; Figure 8 is a pictorial view of an accessory; and Figure 9 is a pictorial view of the accessory of Figure 8 with a plug inserted into it.

DETAILED DESCRIPTION OF THE DRAWINGS

The socket 10 illustrated in Figures 1 and 2 comprises a cover plate 12 which has in it two slots 14 and 16 and an opening 18 for the pins of a plug (not shown). The slot 14 is of elongate rectangular shape and receives a flat blade constituting one of the pins of the plug. The slot 16 is T-shaped and is adapted to receive a blade constituting the other pin of the plug. This other blade can be parallel to the blade which enters the slot 14 or at right angles to the blade which enters the slot 14. In the first form the blade enters the "crossbar" of the T-shaped slot and in the second form it enters the "upright" of the 1-shaped slot. When the socket is orientated as shown in Figure 1 and 2 the crossbar of the T extends vertically.

The surfaces 20 of the cover plate 12 slope towards the slots 14, 16 and opening 18 and constitute guide surfaces.

The opening 18 receives a dummy plug pin, that is, one that is not part of the electrical system, but is provided for operating the shutter mechanism to be described hereinafter.

The cover plate 12 fits onto a base structure 22 best seen in Figures 3 to 7. The base structure 22 has a peripheral rim 24 into which the cover plate 12 fits, the rim 24 projecting from a transverse bottom wall 26 of the base structure 22. Also upstanding from the bottom wall 26 are four sets of guide walls designated 28 and 30. The two guide walls of each of the four sets are parallel to one another and define guides designated 32 and 34. The guides 32 are not parallel but converge in the direction of the centre point of the structure 22. The guides 34 are spaced more widely from one another than are the guides 32. The guides 34 are substantially parallel to the guides 32 and hence also converge.

Walls designated 36 bound spaces for two electrically conductive receptacles designated 38 and 40. The receptacles 38 and 40 each comprise two brass or copper plates 42 which define between them a gap 44. The receptacles 38 and 40 also comprise a further electrically conductive plate 46 which is at right angles to the plates 42. A blade entering through the slot 14 or through the "upright" of the T-shaped slot 16 enters the gap 44 between the plates 42. A blade entering via the cross bar of the T-shaped slot 16 enters the gap between the plate 46 on the one side and the plates 42 on the other side.

Further walls 48 bound a space 50 which receives the dummy plug pin that passes through the opening 20 of the cover plate 12. A spring 54 seats on an abutment 56 upstanding from the bottom wall 26. The function of the spring is described below.

Turning now to Figures 3 and 5, the shutter mechanism 58 is shown in these Figures. The shutter mechanism 58 comprises two shutters 60 each of which has two followers 62, 64 projecting from it. The followers 62 are in the guides 32 and the followers 64 in the guides 34. Each shutter 60 has a slot 66 in one of its two longer edges.

A shutter operating element 68 lies between the shutters 60. The element 68 has protruding lugs 70 which are in the shutter slots 66. The element 68 also has a cross bar 72. Elongate slots 74 are formed in the protruding parts of the cross bar 72. The followers 62 protrude in both directions from the shutters 60 and are located in the slots 74 as well as in the guides 32. The front face of the element 68 has an inclined section 52 which form a ramp. The tip of the dumm,y pin encounters this ramp as it enters the socket. This pushes the element 68 in the "upward" direction as viewed in Figure 3. The spring 54 bears on an abument (not shown) protruding from the rear face of the element 68 and holds the shutter mechanism, in the absence of a dummy pin, in the position shown in Figures 3 and 5.

Electrical terminals which are connected to the receptacles 38 and 40 are shown at 76 and 78 in Figure 7.

When a dummy plug pin enters the socket it encounters the ramp 52 and pushes the element 68, against the action of the spring 54, towards the centre of the base structure 22. The lugs 70 each bear on one of the edges of each slot 66 and displace the shutters 60 in a straight line. However co-operation between the followers 62 and 64 and the guides 32 and 34 constrain the shutters to move apart as well as moving parallel to one another. This exposes both receptacles 38 and 40.

The followers 62, 64 move along the guides 32, 34 and the followers 62 also move outwardly along the slots 74.

As soon as the dummy plug pin is removed, the spring 54 pushes the shutter mechanism back to the position shown whereby the shutters 60 close-off the receptacles 38 and 40.

It will be understood that the dummy pin is longer than the live and neutral pins so that the shutter mechanism only begins to move once the plug is close to the cover plate 12 and the dummy pin partially engaged.

The accessory 80 of Figure 8 includes slots 82 and 84 for receiving the live and neutral pins of a plug and incorporates a dummy pin 86 for operating the shutter mechanism of the socket described above. Arms 88 with a clamping structure 90 at the free ends of the arms 88 enable the accessory to be fastened to a power cord. The accessory enables a plug P (Figure 9) that does not have a dummy pin to be used with a socket as described and illustrated with reference to Figure 1 to 7. The conductive pins of the plug P are designated 92 and 94 and are shown passing through the slots 82 and 84. The clamp mechanism 90 is fastened to the power cord PC which extends from the plug P. -9..

Claims

CLAIMS: 1. An electrical socket comprising first and second electrically conductive receptacles for receiving the pins of an electrical plug, shutters having operative positions in which they conceal said receptacles and prevent said plug pins from entering said receptacles and inoperative positions in which access to the receptacles by said plug pins is possible, characterised by a shutter operating mechanism comprising a shutter activating element located between said shutters and which is constrained to move rectilinearly between an operative position and an inoperative position, links between the shutters and said element so that said shutters move with said element as the element moves between said two positions thereof, and guide means for said shutters, the guide means being such that the shutters, whilst being displaced rectilinearly by said element as the element moves from its operative position to its inoperative position, simultaneously move apart from their operative positions to their inoperative positions.
2. A socket as claimed in claim 1, wherein said guide means comprises guideways which are skew to the rectilinear path along which said element moves, said shutters including followers which are in the guideways.
3. A socket as claimed in claim 2, wherein there are two guideways for each shutter, and each shutter has a follower in each guideway, the guideways for each shutter been parallel to one another and spaced apart in the direction in which said element moves.
4. A socket as claimed in claim 3, wherein said element further includes a crossbar with elongate slots therein, two of said followers being in said slots and in said guideways and, in use, moving along the slots as the shutters move towards and away from one another during movement of said element.
5. A socket as claimed in any preceding claim, wherein said element includes two lugs which are in slots in the shutters, the lugs and shutters being free to move with respect to one another in the direction transverse to said direction in which said element moves.
6. A socket as claimed in any preceding claim and which includes a cover plate having two openings, there being one opening for each of said plug pins, and a third opening for a dummy plug pin, said dummy plug pin displacing said element from its operative position to its inoperative position as it enters said casing through said third opening.