GB2234865A

GB2234865A - Shutter arrangement for an electrical socket outlet

Info

Publication number: GB2234865A
Application number: GB8915324A
Authority: GB
Inventors: Hugh Alexander Connell
Original assignee: TRAVEL ACCESSORIES
Current assignee: TRAVEL ACCESSORIES
Priority date: 1989-07-04
Filing date: 1989-07-04
Publication date: 1991-02-13
Also published as: GB8915324D0

Abstract

A wall 2 of a socket outlet contains a pair of apertures 5, 6 for receiving pins of an electrical plug, and a T-shaped shutter 25 is mounted behind the wall 2. Guide walls 15, 16 guide the stern 28 of the shutter for sliding movement perpendicular to the pins of a plug inserted into the apertures 5, 6. The shutter 25 has inclined faces 32, 33 for engagement by the pins so that the shutter is moved in the operating direction upon simultaneous insertion of the pins. Should an object be inserted into one only of the apertures 5, 6 the shutter undergoes tilting movement relative to the operating direction whereupon the stem 28 moves into engagement with abutment faces 21, 22 of the guide walls 15, 16 to prevent sliding movement in the operating direction. Noses 17, 18 form the pivot points for shutter tilting. <IMAGE>

Description

ELECTRICAL SOCKETS TECHNICAL FIELD OF THE INVENTION This invention relates to electrical sockets of the kind which comprise a number of apertures (almost invariably two or three) for receiving the pins of an electrical plug, and more particularly to the shuttering of such apertures to prevent an article from being inserted therein with a risk of electric shock.

BACKGROUND ART Various proposals exist for preventing an article other than the correct plug from being inserted into the live or neutral aperture of an electrical socket. Often there is a shutter closing the apertures which can only be opened by an earth pin of the plug, but such an arrangement is unsuitable for sockets intended for two pin plugs or for receiving both two and three pin plugs.

SUMMARY OF THE INVENTION An aim of this invention is to provide a shutter mechanism which is suitable for use with two or three pin plugs and which is also smooth and reliable in operation.

The present invention proposes an electrical socket comprising a wall containing a pair of apertures for receiving pins of an electrical plug, a shutter mounted behind the said wall for sliding movement in an operating direction which is substantially perpendicular to a plane which includes the said pins when such a plug is inserted therein, bias means acting on the shutter to urge it into a position in which it closes or substantially closes the said apertures, the said shutter having an inclined face or faces for engagement by the leading ends of the pins so as to move the shutter in the operating direction on insertion of the said pins, and the shutter further being mounted for tilting movement relative to the said operating direction into engagement with abutment means fixed with the said wall to prevent sliding movement in the operating direction.

Thus, should an attempt be made to insert a single pin or other article into one of the apertures the shutter will tilt and lock up to prevent insertion of the article.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is exemplified in the accompanying drawings, in which: Figure 1 is an internal view of an electrical socket of the invention showing the shutter in its normal closed position, Figure 2 is section II-II through the shutter of the socket of Fig. 1, Fugure 3 is a similar view to Fig. 1 but showing the shutter in its open position, and Figure 4 is a similar view to Fig. 1 but showing the shutter in a locked position.

DETAILED DESCRIPTION OF THE DRAWINGS The socket will be described in its normal position of installation as shown, although it will be appreciated that the socket may be installed in any orientation.

The socket comprises a housing 1, which may be of any convenient shape, having a front wall 2 which is surrounded by a side wall 3. The front wall 2 contains three apertures 4, 5 and 6 (best shopwn in Fig. 3) for receiving the earth, neutral and live pins respectively of an electical plug. It will be noted that the apertures 5 and 6 are configured for receiving socalled square pin plugs (the pins of which are actually of rectangular section) and round pin plugs, but this is not relevant to the present invention.

The earth pin aperture 4 is surrounded by a rectangular rearwardly projecting wall 8, the opposite sides of which are extended downwardly at 8a and 8b towards the apertures 5 and 6. Immediately below each of the apertures 5 and 6 there is a respective support wall 12 and 13 which are spaced apart to leave a central gap 14. It will be noted that each wall is shaped to substantially conform to the lower edge of the respective aperture and that the support walls slope downwardly in an outward direction away from the gap 14, as shown. On either side of the gap 14 a pair of guide walls 15 and 16 depend from the inner ends of the respective support walls 12 and 13.The inner surfaces of these guide walls are substantially parallel and vertical except at their upper ends which converge inwardly to form angular pivot noses 17 and 18 at their junctions with the upper surfaces of the support walls 12 and 13. Towards their lower ends the guide walls 15 and 16 are stepped outwardly at 19 and 20 to form thickened and strengthened lower end portions which terminate in end faces 21 and 22 extending perpendicular to the inner faces of the respective guide walls.

The housing contains a T-shaped shutter 25 which is arranged with its cross-arms 26 and 27 superimposed over the apertures 5 and 6 and its central leg 28 disposed between the guide walls 15 and 16. The top face of the shutter has a central pin 29 which projects co-axially with the leg 28, and the lower edges of the arms 26 and 27 are again shaped to conform to the lower edges of the respective apertures 5 and 6. The front face of each arm has an inclined surface 32, 33 respectively, which registers with the respective aperture 5 and 6 and slopes away from the front wall 2 in a downward direction, as best shown in Fig. 2. The side faces of the leg 28 are substantially parallel and are slightly less than the size of the gap 14 between the pivot noses 17 and 18.Towards the lower end of the leg 28, two outwardly stepped shoulders 35 and 36 increase the width of the lower end portion 37 to just less than the spacing between the parallel side faces of the guide walls 15 and 16.

A spring 40 is received about the pin 29 and is located between the extended wall portions 8a, 8b so as to urge the shutter 25 in a downward direction into a position in which the lower faces of its arms 26 and 27 rest upon the pivot noses 17 and 18 and the shoulders 35 and 36 lie just below the end walls 21 and 22 of the guide walls 15 and 16, as shown in Fig. 1.

When the pins L, N and E (Fig. 3) of an electrical plug are inserted into the apertures 4-6 the leading ends of the pins L and N firstly engage the sloping faces 32 and 33 and urge the shutter to slide in a vertically upward direction against the action of the spring 40. The head 37 of the shutter thus slides between the guide walls 15 and 16 and thence guides the shutter to slide smoothly and vertically until the pins can fully enter the apertures 5 and 6 and the condition of Fig. 3 is attained. When operated thus the shutter offers very little resistance to insertion of the plug.

On the other hand, if an attempt is made to insert a single pin or other article into one of the apertures 5 or 6 (say apeture 5 as in Fig. 4) only one of the arms 26 and 27 will be lifted and the shutter will pivot about one of the noses 17 or 18 and tilt relative to a vertical axis. Thus, a respective shoulder 35 or 36 of the head portion 37 will engage beneath the adjacent end face 21 or 22 of the guide walls 15 and 16 to prevent the shutter from lifting further. The pin is thus unable to fully enter the appropriate aperture 5 or 6. In addition, the lower face of the opposite arm 26 or 27 engages the appropriate support wall 12 or 13 to provide firm and positive resistance to further rotational movement of the shutter.

Various possible modifications are envisaged. For example, the single balanced spring 40 could be replaced by two or more springs of substantially equal strength acting on the respective arms 26 and 27. The earth pin could of course be located below the shutter, or it could be omitted altogether in sockets intended exclusively for two pin plugs. The sloping faces 32 and 33 could of course be joined instead of being separate as shown.

Claims

1. An electrical socket comprising a wall containing a pair of apertures for receiving pins of an electrical plug, a shutter mounted behind the said wall for sliding movement in an operating direction which is substantially perpendicular to a plane which includes the said pins when such a plug is inserted therein, bias means acting on the shutter to urge it into a position in which it closes or substantially closes the said apertures, the said shutter having an inclined face or faces for engagement by the leading ends of the pins so that the shutter is moved in the operating direction on insertion of the said pins, and the shutter further being mounted for tilting movement relative to the said operating direction into engagement with abutment means fixed with the said wall to prevent sliding movement in the operating direction upon insertion of an object into one only of the said apertures.

2. An electrical socket according to Claim 1, in which the shutter comprises a trailing stem portion which extends opposite to the operating direction between a pair of guide walls, the stem portion including a pair of projections disposed on opposite sides thereof, and the abutment means comprises abutment faces of the said guide walls, the arrangement being such that upon movement of the shutter in the operating direction the projections pass unimpeded between the said guide walls but upon said tilting movement of the shutter one of the projections moves into engagement with a respective one of the said abutment faces.

3. An electrical socket according to Claim 2, in which the ends of the said guide walls disposed in the operating direction are provided with inwardly directed pivot noses about which the shutter pivots during said tilting movement.

4. An electrical socket according to Claim 2 or 3, in which support walls are provided adjacent to the ends of the said guide walls disposed in the operating direction, to limit tilting of the shutter upon said tilting movement.

5. An electrical socket according to any of Claims 2 to 4, in which the bias means comprises compression spring means disposed on the opposite side of said shutter to said stem portion and acting between an abutment fixed with the wall which contains said apertures and said shutter.

6. An electrical socket according to any preceding claim, in which the shutter is substantially T-shaped.

7. An electrical socket substantially as described with reference to the drawings.