GB2477313A

GB2477313A - Electrical socket with shutter mechanism

Info

Publication number: GB2477313A
Application number: GB1001464A
Authority: GB
Inventors: Lawrence Murray Lonergan
Original assignee: Electrium Sales Ltd
Current assignee: Electrium Sales Ltd
Priority date: 2010-01-29
Filing date: 2010-01-29
Publication date: 2011-08-03
Anticipated expiration: 2030-01-29
Also published as: CN102754283B; GB201001464D0; CN102754283A; GB2477313B; SA111320143B1; WO2011092494A1

Abstract

An electrical socket includes a shutter mechanism to prevent misuse of the socket, such as insertion of objects to connect to the electrical terminals other than the appropriately configured plug. The shutter mechanism comprises first 11 and second 12 members which are moveable between an initial position covering respective terminals and a retracted position. When the first member 11 is retracted in direction 20, e.g. upon insertion of an earth pin of a plug, the second member 12 slidably engages the first member 11 when the second member 12 is retracted, e.g. upon insertion of other pins (e.g. neutral and live pins) thus exposing the corresponding terminals of the socket permitting connection. When the first member 11 is in its initial position, the second member 12 rocks or pivots upon insertion of the neutral and live pins and the second member 12 engages the first member 11 to prevent relative sliding movement. As a result, the terminals remain covered by the second member 12. Both members 11, 12 may be provided with a ramping surface 18 to provide transverse movement of the members 11, 12 when a connector is mated.

Description

An electrical socket with a shutter mechanism for an electrical connector This invention relates to an electrical socket with a shutter mechanism for an electrical connector.

Electrical sockets in the UK include three terminals into which corresponding pins of a plug may be inserted when the plug is mated to the socket. The pins are to enable the connection to a live, neutral and earth of an electrical supply. A shutter mechanism is provided which aims to prevent misuse by the insertion of objects into the live and neutral terminals before the earth connection is properly made. The mechanism requires insertion of the earth pin of the plug before the neutral and live terminals are exposed.

This prevents the insertion of, for example a screw-driver or other inappropriate object, into the live terminal before an earth connection is made.

It has been found, however, that some existing shutter mechanisms are not completely infallible. Because of play in such existing mechanisms the safety aspect may be circumvented leading to potential injury to the person subjecting the socket to misuse through electrical shock.

The present invention arose to provide an improved shutter mechanism.

According to the invention there is provided an electrical socket comprising a plurality of electrical connectors to which matching connectors are intended in use to be mated, a shutter mechanism for preventing connection to the electrical connectors comprising a first member adjacent a first terminal and moveable, by mating of a connector to the terminal, from an initial position to a retracted position, a second member in a first initial position covering at least a second terminal to prevent connection thereto of a connector which second member slidably engaging the first member when located in the retracted position to permit relative movement therebetween to allow connection to the at least one terminal and being pivotable under the action of a connector being moved to mate with the at least one terminal when the first member is in the initial position such that the member engages the first member to prevent relative sliding movement therebetween to retain the second member in a position covering the at least one terminal.

This type of mechanism is considered to be more secure against tampering than prior art arrangements and is simpler and more convenient to manufacture. Furthermore, insertion of a first pin does not result in the other terminal being opened. This requires a pin to be used at that location as well.

A specific embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings of which: Figure 1 shows a three pin plug and socket in accordance with the invention; and Figure 2 show a shutter mechanism of the socket shown in figure 1 in various operational states.

As is shown in figure 1, a socket 1 is provided in accordance with the invention connected to a mains supply shown in broken outline. Typically the socket will be located in or on a wall surface in a building. The socket 1 has three holes 2 to 4 in a front face plate. The upper hole 2 is aligned with an internal terminal connected to earth of the supply, and holes 3 and 4 are aligned with terminals connected to the live and neutral. To connect an appliance 5 to the power supply, the plug 6, which has three pins 7, 8 and 9, is aligned with the socket and the pins inserted and pushed into the holes.

The act of inserting the pins into the holes operates a shutter mechanism in a manner to be later described.

Figure 2 shows the internal components of the socket 1. In figure 2 a, the socket is shown with the cover plate removed and the internal components at their initial position prior to insertion of the pins of the plug. In order to understand the orientation, labelled arrow 1 0 shows the direction of insertion of the plug into the socket from a position above the socket. The socket shutter mechanism comprises first and second members 11 and 12.

The first member 11 comprises three integrally moulded arms 13, 14 and 15. The outer arms 13 and 15 include latches 16 and 17 at their ends. The inner arm 14 comprises an earth pin ramping surface 18. As the plug is inserted into the socket along the direction 10, the earth pin 7 engages the ramping surface 18 and pushes the first member in the direction of arrow 20 in the plane of the major face of the socket. This action is shown again in more simplified form in the side view of figure 2b. The first member 11 is slideably located in a void of the material to facilitate smooth movement. The void is configured to limit and constrain the movement as required. The movement gradually reveals the earth terminal 21 to allow electrical connection by the earth pin 7 as shown in figure 2c.

In the condition shown in figure 2c, it will be seen that the latches 16 and 17 have moved into a position overlying arms of the second latching member 12. The second member 12 comprises two arms 22 and 23 subtending from a transverse arm 24. It is located within a recess in the cover plate in its initial position such that ramped ends 25 and 26 located at the junction between the arms 22, 23 and the transverse arm 24 cover the neutral and live terminals 27, 28. The second member 12 is mounted in the recess to have two possible modes of movement. A first mode of movement occurs when the mechanism is in the state shown in figure 2c that is to say the earth pin is fully inserted and the first member 11 overlaps the second member. When restrained by this overlap, insertion of the neutral and live pins 8, 9 results in their engagement with the ramping surfaces 25 and 26. Insertion results in sliding movement of the second member in the plane of the socket as indicated by labelled arrow 29 until the neutral and live terminals are fully exposed as shown in figure 2d. Theses phases are the normal mode operation which allow correct insertion of a plug. The mechanism prevents abuse operation in a manner to be described as follows.

Figure 2e shows an abuse situation. In this the other mode of movement of the second member 12 will be apparent. In figure 2e, it will be seen that the earth pin has not been inserted and that the first member is not overlapping the second member 12 (see also side view figure 2f). In this position the member 12 is able to pivot. This results in the arms 22, 23 moving upwards to abut the ends of the 16 and 17 of the first member.

Relative sliding movement is therefore blocked and the neutral and live terminals 27 and 28 remain covered by the ramping surfaces 25 and 26. Accordingly, connection to the neutral or live terminals is prevented in this abuse operation in which no earth pin is inserted. Figure 2g shows a side view corresponding to the figure 2c-the non-abuse configuration. In this position, relative sliding movement is possible to allow the revealing of the neutral and live terminals as shown in figure 2d.

It will be appreciated that resilient biases such as spring members will be provided to return the shutter mechanism to its initial position when the plug is removed. These have been omitted for clarity.

The invention has been described in the context of a domestic three pin power supply. It will be readily appreciated that the invention will also be applicable to other sorts of supply or electrical connections.

Claims

Claims 1. An electrical socket comprising a plurality of electrical connectors to which matching connectors are intended in use to be mated, a shutter mechanism for preventing connection to the electrical connectors comprising a first member adjacent a first terminal and moveable, by mating of a connector to the terminal, from an initial position to a retracted position, a second member in a first initial position covering at least a second terminal to prevent connection thereto of a connector which second member slidably engaging the first member when located in the retracted position to permit relative movement therebetween to allow connection to the at least one terminal and being pivotable under the action of a connector being moved to mate with the at least one terminal when the first member is in the initial position such that the member engages the first member to prevent relative sliding movement therebetween to retain the second member in a position covering the at least one terminal.
2. An electrical socket as claimed in claim 1 wherein the first member is provided with a ramping surface in use abutted by an electrical connector as the connector is mated to the terminal to provide transverse movement of the member from the initial position to the retracted position.
3. An electrical socket as claimed in claim 1 or 2 wherein the second member is provided with a ramping surface against which a connector to be mated with the at least one terminal cooperates to provide the transverse sliding movement of the second member relative to the first when the first member is in the retracted position and the pivoting movement when the first member is in the initial position.
4. An electrical socket substantially as hereinbefore described.