GB2443452A

GB2443452A - Electric switch assemblies

Info

Publication number: GB2443452A
Application number: GB0621964A
Authority: GB
Inventors: Lin Lih Goh
Original assignee: Novar ED&S Ltd
Current assignee: Novar ED&S Ltd
Priority date: 2006-11-03
Filing date: 2006-11-03
Publication date: 2008-05-07
Also published as: GB0621964D0

Abstract

An electric switch assembly including a rocker switch member 3 which is accessible at a front face 21 of the assembly and is movable to cause activation of the switch assembly, and a blocking arrangement 5 having a first condition for physically blocking movement of the switch member 3 to prevent actuation of the switch and a second condition for allowing movement of the switch member 3 to cause activation of the switch assembly. The blocking arrangement 5 is generally disposed to the rear of the front face 21 of the assembly but includes a part 6 accessible through an opening in the front face of the assembly and comprising a socket of non-circular cross-section engageable by a key for routine the accessible part to move the blocking arrangement 5 between the first and second conditions.

Description

Electric Switch Assemblies This invention relates to electric switch

assemblies.

It is sometimes desirable to be able to prevent inadvertent operation of an electric switch, for example to prevent it being switched on accidentally. The present invention seeks to provide such an arrangement in a manner that enables a relatively high level of security to be achieved without unduly affecting the appearance or functionality of the switch.

According to the invention there is provided an electric switch assembly including an actuator mechanism which is accessible at a front face of the assembly and is movable to cause activation of the switch assembly, arid a blocking arrangement having a first condition for physically blocking movement of the actuator mechanism to prevent actuation of the switch and a second condition for allowing movement of the actuator mechanism to cause activation of the switch assembly, the blocking arrangement being generally disposed to the rear of the front face of the assembly but including a part accessible through an opening in the front face of the assembly and comprising a socket of non-circular interior cross-section engageable by a key for rotating the accessible part to move the blocking arrangement between the first and second conditions.

The accessible part of the blocking arrangement is preferably the only part of the blocking arrangement visible from the front of the switch. The socket is preferably of small size and may for example have an interior cross-sectional area of less than 50mm2 Whilst it is within the scope of the invention for the socket of the accessible part to be recessed behind the opening in the front face of the assembly or to project forwardly of the front face, it is preferred that the front of the socket is substantially flush with the front face of the switch assembly. That again enables the visual impact of the blocking arrangement to be reduced.

The socket is preferably of generally polygonal interior cross-section. The corners of the polygonal interior are preferably curved and more preferably the sides of the polygonal interior are also curved. The curvature of the corners may be substantially sharper than the curvature of the sides. A socket of generally triangular cross-section has proved especially advantageous in enabling good torque to be applied by a suitable key inserted into the socket whilst allowing the socket to remain small, thereby enabling its visual impact to be reduced.

The assembly may further include a key for rotating the accessible part to move the blocking arrangement between the first and second conditions. The key preferably is of elongate shape and has an end portion of non-circular cross-section matched to the interior cross-section of the socket for insertion therein. Thus the cross-section of the end portion may have curved corners and curved sides matching the preferred form of the recess in the accessible part of the blocking arrangement. The key is preferably a close fit in the recess.

Whilst it is within the scope of the invention for the actuator mechanism to comprise a plurality of parts and for the blocking arrangement to interact with one of the parts that is not itself directly contacted by a user, it is preferred that the actuator mechanism comprises a switch member, preferably a rocker switch member and that the blocking arrangement directly blocks movement of the rocker switch member in the first condition of the blocking arrangement. The first and second conditions of the blocking arrangement may simply correspond to first and second positions of the blocking member. Preferably the blocking member is rotatable between the first and second positions. The rotation of the blocking member is preferably restricted such that it can rotate between the first and second positions but not substantially beyond those positions. For example, the first and second positions may be spaced apart by about a quarter turn of the blocking member and rotation of the blocking member beyond that range may be prevented, for example, by a radially extending arm on the blocking member engaging a fixed part of the switch assembly.

The blocking member preferably includes an opening which, in the unbiocking position of the blocking member, accommodates a part of the actuator mechanism to allow actuation of the mechanism.

Preferably the blocking member is movable from the second unbiocking position into the first blocking position only when the actuator mechanism is in a deactivated position (so the switch is off') . Such an arrangement ensures that the switch cannot be locked in the on' state.

The assembly is preferably an electric wall switch assembly. In an embodiment of the invention described below the assembly comprises a single switch but it is within the scope of the invention for more than one switch to be provided on the assembly; in that case a single blocking arrangement may be arranged to block all the switches or a separate blocking arrangement may be provided for each switch.

By way of example an embodiment of the invention will now be described with reference to the accompany drawings, of which: Fig.1A is an isometric view of an electric switch assembly, Fig.1B is a front view of the switch assembly of Fig. 1A, Fig.1C is side view of the switch assembly of Fig. 1A, Fig.2A is an isometric view of a blocking member incorporated in the switch assembly of Figs. 1A to 1C, Fig.23 is a front view of the blocking member of Fig. 2A, Fig.3 is an isometric view of a key for rotating the blocking member of Figs. 2A and 2B.

Figs.4A and 4B show in respective, cut-away, side views a rocker member of the switch assembly in a switched off position (F'ig.4A) and a switched on position (Fig.4B), with the blocking member of Figs.2A and 2B in an unbiocking position, Figs.5A and 56 show in schematic views from behind, the rocker member of the switch assembly in the switched off position (Fig.5A) and the switched on position (Fig.5B), with the blocking member of Figs.2A and 2B in an unbiocking position, and Fig.6 shows in a schematic view from behind, the rocker member of the switch assembly in the switched off ph position, with the blocking member of Figs.2A and 2B in a blocking position.

Referring first to Figs.1A to 1C, there is shown an electric wall switch assembly which in most respects is of a conventional kind. The assembly includes a central front plate 1 around which a flush fitting border member 2 is provided. A rocker switch member 3 is mounted in a rectangular opening in the front plate 1 and, in this example, can be pressed inwardly at the top to rock the switch member 3 to an on' position or pressed inwardly at the bottom (as shown in Figs.1A to 10) to rock the switch member 3 to an off' position. The front plate 1 and the border member 2 together define a front face 21 of the switch assembly.

A terminal block 4 is mounted on the rear of the front plate and includes terminals for receiving the ends of cables and a switch mechanism that is operated by the rocker switch member 3. The terminals and switch mechanism are of conventional design. In the particular example illustrated, the switch is a 3 pole fan isolator switch.

In a standard rocker switch assembly the rocker switch member is always free to be moved between its on' and off' positions, but in the switch assembly embodying the invention a facility is provided for blocking movement of the rocker switch member 3 so that it cannot be moved into the on' position, as will now be described.

Referring also to Figs.2A and 2B, the switch assembly embodying the invention includes a blocking member having a front part 6 of circular external cross-section and a rear part 7. The front plate 1 is formed with a circular aperture which in this example is located below the switch member 3 and to one side of the centre of the member 3, and which receives the front part 6 of the blocking member 5, so that the front face of the blocking member 5 is approximately flush with the front face of the plate 1. The depth of the front part 6 of the blocking member 5 is approximately the same as the depth of the front plate 1 and shoulders 8, 9 on the rear part 7 of the blocking member engage the rear face of the plate 1 to prevent the blocking member passing through the aperture in the front plate. The rear part 7 is received in a recess in the terminal block 4 which in turn prevents rearward movement of the blocking member.

The rear part 7 of the blocking member 5 is formed with a radially projecting arm 10 which includes a forward projection 11 that can be accommodated in recesses (not visible in the drawings) in the rear face of the front plate 1 at the two end positions of the blocking member.

The recess is of limited extent such that the rotation of the blocking member 5 relative to the front plate 1 is limited to about 90 degrees in an anti-clockwise direction from the position shown in Fig.2B.

The front part 6 of the blocking member 5 is in the form of a socket and is provided with a recess 12 of constant, generally triangular shape. In the example shown each corner of the recess is radiused with a first radius of curvature and each side of the recess is radiused with a second radius of curvature much larger than the first. In a particular example the first radius of curvature is 1.5mm and the second radius of curvature is 6.5mm. In that example, the external diameter of the front part 6 is 8.1mm and the cross-sectional area of the recess 12 is less than 50mm2.

The front face of the front part 6 is generally flat apart from a raised portion 13 in the shape of an arrowhead, enabling a user to identify the rotational position of the blocking member 5. The front face 21 of the switch assembly may be provided with markings (not shown in the drawings) such as "locked" and "unlocked" positioned in relation to the arrowhead to indicate the positions of the blocking member 5.

The rear part 7 of the blocking member 5 is of generally annular shape defining a recess 19, open at its rear and open in one lateral direction (that direction being the upward direction when the blocking member is in the position shown in Fig..2B.

A key 14, shown in Fig.3, is provided with the switch assembly to allow a user to rotate the blocking member 5.

The key 14 has an end portion 15 of a generally curved triangular shape matched to the recess 12 in the blocking member 5 so that it is a close fit in the recess. A main body part 16 of the key is of larger cross-section than the end portion 15 and is of hexagonal shape, enabling a user to grip the body part 16 and rotate it. An end portion 17 of the key includes an opening 18 by which the key can, if desired, be attached to a key ring.

Operation of the blocking member 5 will now be described with reference to E'igs.4A, 4B, 5A, 5B and 6.

As can be seen especially well in Figs.5A and 5B the rocker switch member 3 differs from a standard member in that it has a projecting lug 20 on its bottom edge of a size that can comfortably be accommodated with the recess 19. When the rocker switch member 3 is in the off' position shown in Figs.1A to lC the lug 20 is to the rear of the blocking member 5 and the blocking member 5 has no effect. That position of the parts is shown in Figs.4A and 5A with the blocking member 5 shown in the position also shown in Fig.2B, namely the unbiocking position. In this position of the blocking member 5, the recess 19 is aligned with the lug 20 and the rocker switch member 3 can be rocked to the on' position. That rocking action causes the lug 20 on the bottom of the rocker switch member 3 to -10 -move forwards into the recess 19 and to take up the position shown in Figs.4B and 5B. Of course, the rocker switch member 3 can then be rocked back to the off' position when desired.

With the rocker switch member 3 in the off' position, the blocking member 5 can be rotated about 90 degrees anti-clockwise as viewed from the front, into the position shown in Fig.6. That is done by a user inserting the end portion of the key into the recess 12 in the front part 6 of the blocking member and then turning the key. In the new position the lateral opening to the recess 19 is no longer aligned with the lug 20 of the blocking member 5. The contact of the lug 20 with the blocking member 5 therefore prevents the rocker switch member 3 being moved into the on' position.

Claims

-11 -Claims: 1. An electric switch assembly including an actuator

mechanism which is accessible at a front face of the assembly and is movable to cause activation of the switch assembly, and a blocking arrangement having a first condition for physically blocking movement of the actuator mechanism to prevent actuation of the switch and a second condition for allowing movement of the actuation mechanism to cause activation of the switch assembly, the blocking arrangement being generally disposed to the rear of the front face of the assembly but including a part accessible through an opening in the front face of the assembly and comprising a socket of non-circular cross-section engageable by a key for rotating the accessible part to move the blocking arrangement between the first and second conditions.
2. An assembly according to claim 1, in which the socket has an interior cross-section of less than 50mm2.
3. An assembly according to claim 1 or 2, in which the front of the socket is substantially flush with the front face of the switch assembly.

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4. An assembly according to claim 2 or 3, in which the socket is of generally polygonal interior cross-section.
5. An assembly according to any of claims 2 to 4, in which the socket is of generally curved polygonal interior cross-section.
6. An assembly according to claim 4 or 5, in which the socket is of generally triangular interior cross-section.
7. An assembly according to any preceding claim, further including a key for rotating the accessible part to move the blocking arrangement between the first and second conditions.
8. An assembly according to claim 7, when dependent upon claim 2, in which the key is of elongate shape and has an end portion of non-circular cross-section matched to the interior cross-section of the socket for insertion therein.
9. An assembly according to any preceding claim, in which the actuator mechanism comprises a rocker switch member.
10. An assembly according to claim 9, in which the blocking arrangement directly blocks movement of the rocker -13 -switch member in the first condition of the blocking arrangement.
11. An assembly according to any preceding claim, in which the blocking arrangement comprises a blocking member movable between a first blocking position and a second unbiocking position.
12. An assembly according to claim 11, in which the blocking member is rotatable between the first blocking position and the second unbiocking position.
13. An assembly according to claim 11 or 12, in which the blocking member includes an opening which, in the unbiocking position of the blocking member accommodates a part of the actuator mechanism to allow actuation of the mechanism.
14. An assembly according to any preceding claim, in which the blocking member is movable from the second unbiocking position into the first blocking position only when the actuator medium is in a deactivated position.
15. An assembly according to any preceding claim, comprising an electric wall switch assembly.

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16. An electric switch assembly substantially as herein described with reference to the accompany drawings.