GB2278245A

GB2278245A - Device for shielding an electrical plug

Info

Publication number: GB2278245A
Application number: GB9405717A
Authority: GB
Inventors: Robert Edgar Marzetti; Peter Anthony Baker Prosser; Anthony Kenneth Harwood; George Alexander Jones; Andrew John Chipling
Original assignee: SWITCHGUARD Ltd
Current assignee: SWITCHGUARD Ltd
Priority date: 1993-05-17
Filing date: 1994-03-23
Publication date: 1994-11-23
Also published as: GB9317118D0; GB9405717D0; GB9310147D0

Abstract

A device for shielding an electrical plug which is inserted into an electrical socket comprises a support (1) for locating on the front face of the socket and a removable cover (2) for obstructing access to the plug. The cover (2) is removably attached to the support (1) by interengageable interference fit parts which comprise flexible arms (11) on the cover (2) arranged to engage between projections (4) on the support (1) and an upper shelf (5) on the support (1) arranged to engage with an upper edge of the cover (2). The plug pins may be inserted into the socket through an aperture in the support (1) or a central portion of the support (1) may be removable to enable insertion of the pins. An adhesive or adhesive tape may be used to secure the support (1) to the front face of the socket. <IMAGE>

Description

DEVICE FOR SHIELDING AN ELECTRICAL PLUG The present invention relates to a device for shielding an electrical plug, for example a conventional three-pin plug.

There are many electrically-operated machines for which it is necessary to ensure a continuous supply of power in order to avoid, for example, any loss or damage to the contents of the machine or undesirable consequences for which the machine may be monitoring. Examples of such machines are freezers and fridges in domestic use for food storage, incubators and fridges used for medical and research purposes, medical monitoring equipment, computer systems and burglar alarms. In general, these machines are simply connected to the power supply by a plug and socket arrangement. However, it may be possible to easily remove the plug so that the socket may be used for other purposes, thereby disconnecting a vital power supply to a particular machine.

It is therefore an object of the invention to provide a device for shielding an electrical plug which is simple and yet effective in providing a warning that the plug should not be removed from its socket.

Accordingly, the present invention consists in a device for shielding an electrical plug which is inserted into an electrical socket, said device comprising support means for mounting on the front face of the socket and arranged to support a cover for obstructing access to the plug, the cover being removably attached to the support means by interengageable parts provided on the cover and the support means.

In a preferred embodiment, the interengageable parts are arranged to co-operate with each other in an interference - or snap-fit manner.

In one example, the interengageable parts comprise flexible arms formed on the cover which are arranged to interengage between projections formed on the support means.

The flexible arms and projections may be provided with cooperable tongue and groove means to aid in securing the cover to the support means. The support means may be provided with an upper portion extending generally perpendicular to the main body of the support means and the interengageable parts may include co-operable means formed on the upper portion of the support means and an upper portion of the cover. In one arrangement, the co-operable means comprise a groove formed in the upper portion of the support means into which an upper edge of the cover is adapted to engage.

At least part of the support means may be intended to be located between the front face of the socket and the plug body, and the support means may be provided with at least one aperture through which one or more pins of the plug can pass when the plug is inserted into the socket.

Alternatively, the support means may be provided with means for mounting it to the front face of the surround of the socket and may have a central portion which can be removed to enable the pins of the plug to be inserted into the socket. Preferably, the central portion is shaped and dimensioned such that when it is removed no part of the support means is located between the front face of the socket and the plug body. The device may be provided with means for locating the support means in the correct position on the surround. In one example, the locating means may consist of at least one projection formed on the removable central portion which is arranged to be inserted into at least one inlet of the socket prior to removal of the central portion from the remainder of the support means. In another example, the locating means may comprise at least one aperture formed in the removable central portion through which one or more pins of the plug can pass, thereby enabling the plug to be inserted into the socket without necessarily removing the removable central portion. The central portion may be attached to the remainder of the support means by breakable connecting members.

The cover may be shaped so as to shield an electrical switch on the socket as well as the plug inserted in the socket.

Embodiments of the invention will now be described with reference to the accompanying drawings, in which: Figure 1 shows a perspective view of an electrical plug shielded by a device in accordance with a first embodiment of the invention, Figures 2 and 3 show respectively a front elevation and a side elevation of a support of the device shown in Figure 1, Figure 4 shows a side elevation of a cover of the device shown in Figures 1 to 3, Figure 5 shows a front elevation of a support of a device according to a second embodiment of the invention, Figure 6 shows a partially sectional side view of the support shown in Figure 5, and Figure 7 shows a front elevation of a support for a device according to a third embodiment of the invention.

Referring firstly to Figures 1 to 4, the device basically comprises a support 1 and a removable cover 2.

The support 1 includes a thin flat plate 3 shaped substantially as an inverted T, that is, being of generally rectangular shape with oppositely extending flanges 3a projecting from the lower region of each long side of the rectangular shape. At the ends of the flanges 3a, projections 4 extend forwardly generally perpendicular to the plane of the plate 3. The projections 4 extend around the lower corners of the flanges 3 and slightly along the lower edges thereof. On the inside of each projection 4 adjacent the plane of the plate 3 is formed a latching groove 4a (see Figure 1) which extends from the lower end of the projection 4 to the upper edge of the flanges 3a.

At the top edge of the plate 3, a shelf 5 extends forwardly perpendicular to the plane of the plate 3. The shelf 5 includes strengthening flanges 6, 7 at its side and rear edges. The side flanges 6 taper towards the outer edge of the shelf 5 remote from the plate 3, and the rear flange 7 is a continuation of the plate 3.

A shallow groove 8 runs across the underside of the shelf 5 at the outer edge thereof, the groove 8 having an arc-shaped transverse cross-section.

In the centre of the plate 3 is an aperture 9 of generally triangular shape with truncated corners having a cross-shaped part extending from the apex of the triangular shape.

The cover 2 includes a substantially rectangular plate 10 having two arms 11 which extend substantially at right angles to the plane of the plate from the lower half of the side edges thereof. The upper edges of the arms 11 curve down from the plate 10 and then extend perpendicularly to the plane of the plate, the free ends of the arms 11 having substantially the same width as that of the projections 4 of the support 1. The arms 11 are flexible so that they can move slightly towards and away from each other in a direction generally parallel to the plane of the rectangular plate 10. On the outer side face of each arm 11 at its free end is a narrow latching tongue lla extending along the width of the arm.

An upper edge (not shown) of the rectangular plate 10 is rounded with a similar profile to that of the groove 8.

On either side of this upper edge, lugs 12 extend up from the side edges of the rectangular plate 10 above the upper edge, and are bent substantially through a right angle and extend generally parallel to the arms 11.

To mount the support 1 on the front face of a conventional electrical socket, the thin plate 3 is firstly held adjacent to the front face of the socket with the three socket inlets visible through the aperture 9. A conventional electrical plug is inserted into the socket, with the plug pins engaging in the socket inlets through the aperture 9. In this way the support 1 is securely held between the plug body and the surround of the socket and is located accurately by the alignment of the aperture 9 with the pins of the plug and the socket inlets.

The cover 2 is then interengaged in an interference fit or snap-fit to the support 1 in the following manner.

The cover 2 is held so that the rounded surface of the upper edge of the rectangular plate 10 engages in the shallow groove 8 in the shelf 5. The arms 11 are squeezed towards each other until the latching tongues lla fit inside the projections 4. The lower part of the cover is pushed towards the support 1 until the latching tongues lla engage in the latching grooves 4a in the projections 4. When the arms are released, they move away from each other such that the tongues lla are forced further into the grooves 4a. In this way, the cover is held firmly by the projections 4 which support the arms 11 along their lower edges, thereby ensuring the engagement of the rounded upper edge of the plate 10 in the groove 8.

In this position the cover 2 shields the electrical plug and prevents its inadvertent removal, as the plug may not be removed without first removing the cover 2. This requires a positive action involving squeezing the arms 11 towards each other to disengage the latching tongues lla from the latching grooves 4a and then pulling the cover away from the support thus disengaging it from the support groove 8. Since only the arms 11 need be held by the user, removal of the cover can be achieved easily and rapidly if necessary.

A further advantage of the cover when held by the support is that one of the lugs 12 serves to shield the electrical switch which is generally provided on one side of the surround of the socket. The lug 12 can thus also guard against accidental operation of the switch.

Figures 5 and 6 show an alternative support 1', in which the thin plate is divided into an upper portion 13 which has the shelf 5, a central portion 14, and a lower portion 15 which has the projections 4.

The upper and central portions 13, 14 are divided by a narrow gap extending across the width of the plate, and the central and lower portions 14, 15 are divided by another narrow gap 17 which extends generally parallel to the gap 16 along the central part of its length and turns through two angles of approximately 45" at each end so that its ends are orientated generally perpendicular to the central part thereof. The gaps 16, 17 are each bridged by two thin connecting members 18 so that the support 1' can be initially supplied as a single unit.

The central portion 14 does not have the aperture 9 shown in Figure 2. Instead, on the rear side of the central portion 14 are three locating blocks 19 (only two of which are visible in Figure 6). The blocks 19 have identical cross sections and relative positions as the pins of a conventional three-pin electrical plug. The ends of the blocks 19 are tapered in the same way as conventional plug pins to facilitate partial insertion into the socket inlets.

On the rear side of the upper and lower portions 13, 15 is provided adhesive means such as foam-backed adhesive tape (not shown).

The support 1' is mounted to a conventional electrical socket by pressing it against the surround so that each of the locating blocks 19 is inserted into one of the inlets of the socket. The support 1' is then held in place by the adhesion of the adhesive tape on the upper and lower portions 13, 15 to the surround of the socket.

Next, a suitable tool is used to break the connecting members 18. The central portion 14, which serves only to locate the upper and lower portions 13, 15 on the socket surround by means of the blocks 19, is then removed and discarded. An electric plug is inserted into the socket and the cover 2 is interengaged with the support portions 13, 15 to shield the plug as described hereinabove.

In the embodiment shown in Figures 5 and 6, once the central portion 14 has been removed, the plate of the support 1' does not extend between the socket and the plug body, so that it enables the pins of the plug to be fully inserted into the socket inlets.

Figure 7 shows another embodiment in which like parts are labelled with like reference numerals with respect to the other Figures. In this embodiment, a support 1" has the same removable central portion 14 as in the embodiment of Figures 5 and 6, but instead of locating blocks 19 it is provided with an aperture 9 to locate the upper and lower portions 13, 15 in the correct position on the socket surround. In order to locate correctly the support 1" on the socket surround, the plug pins are inserted through the aperture 9 into the socket and the support 1" is secured in place on the surround. The plug can then be removed from the socket and central portion 14 can also be removed by breaking the connecting members 18 whilst portions 13, 15 remain on the surround. The advantage of this embodiment over that of Figures 5 and 6 is that it is not essential for portion 14 to be removed before the plug can be inserted into the socket.

The device of any of these embodiments is preferably formed from a plastics material, in which case the support and the cover may each be moulded as an integral unit.

Whilst particular embodiments have been described, modifications will be envisaged without departing from the scope of the invention. For example, a message which warns against removal of the plug from the socket may be applied to the front face of the cover.

Additionally or alternatively, the support of the device shown in Figures 1 to 4 may be fixed to the surround of the socket by any suitable means, such as adhesive tape, instead of merely being held against the front face of the socket by the plug body. The aperture in the support means of the first and third embodiments may be any suitable shape to enable insertion of one or more of the pins of plugs of different sizes and shapes. Alternatively, more than one aperture may be provided for insertion of one or more of the plug pins.

Claims

1. A device for shielding an electrical plug which is inserted into an electrical socket, said device comprising support means for mounting on the front face of the socket and arranged to support a cover for obstructing access to the plug, the cover being removably attached to the support means by interengageable parts provided on the cover and the support means.

2. A device as claimed in claim 1, wherein the interengageable parts are arranged to co-operate with each other in an interference - or snap-fit manner.

3. A device as claimed in claim 2, wherein the interengageable parts comprise flexible arms formed on the cover which are arranged to interengage between projections formed on the support means.

4. A device as claimed in claim 3, wherein the flexible arms and projections are provided with co-operable tongue and groove means to aid in securing the cover to the support means.

5. A device as claimed in claim 2, 3 or 4, wherein the support means is provided with an upper portion extending generally perpendicular to the main body of the support means and the interengageable parts include co-operable means formed on the upper portion of the support means and an upper portion of the cover.

6. A device as claimed in claim 5, wherein the co-operable means comprise a groove formed in the upper portion of the support means into which an upper edge of the cover is adapted to engage.

7. A device as claimed in any preceding claim, wherein at least part of the support means is intended to be located between the front face of the socket and the plug body, and the support means is provided with at least one aperture through which one or more pins of the plug can pass when the plug is inserted into the socket.

8. A device as claimed in any one of claims 1 to 6, wherein the support means is provided with means for mounting it to the front face of the surround of the socket and has a central portion which can be removed to enable the pins of the plug to be inserted into the socket.

9. A device as claimed in claim 8, wherein the central portion is shaped and dimensioned such that when it is removed no part of the support means is located between the front face of the socket and the plug body.

10. A device as claimed in claim 8 or 9, including means for locating the support means in the correct position on the surround.

11. A device as claimed in claim 10, wherein the locating means comprises at least one projection formed on the removable central portion which is arranged to be inserted into at least one inlet of the socket prior to removal of the central portion from the remainder of the support means.

12. A device as claimed in claim 10, wherein the locating means comprises at least one aperture formed in the removable central portion through which one or more pins of the plug can pass, thereby enabling the plug to be inserted into the socket without necessarily removing the removable central portion.

13. A device as claimed in any one of claims 8 to 12, wherein the central portion is attached to the remainder of the support means by breakable connecting members.

14. A device as claimed in any preceding claim, wherein the cover is shaped so as to shield an electrical switch on the socket as well as the plug inserted in the socket.

15. A device substantially as herein described with reference to Figures 1 to 4, or 5 and 6, or 7 of the accompanying drawings.

16. An electrical socket for an electrical plug, said socket having a device as claimed in any preceding claim provided on a front face thereof.