GB2160031A

GB2160031A - Shutter of plug socket

Info

Publication number: GB2160031A
Application number: GB08414648A
Authority: GB
Inventors: Arthur Bates
Original assignee: BSR
Current assignee: BSR
Priority date: 1984-06-08
Filing date: 1984-06-08
Publication date: 1985-12-11
Also published as: GB2160031B; GB8414648D0

Abstract

A plug socket includes a face plate 10 to the rear surface of which is secured a housing 13 accommodating a shutter mechanism disposed between pin apertures in the face plate and electrical contact elements. The shutter mechanism comprises a pair of transversely slidable members 16 biased to an operative position to prevent access to the contact elements by a pair of springs 26. The members can tilt to disengage abutment surfaces 27, 29 on each member to allow movement of the members to the inoperative position only if both members are tilted at the same time. If one member only is tilted, the abutment surface 29 on the one member will remain engaged with the abutment surface 27 on the other member to prevent movement of the members to the inoperative position. <IMAGE>

Description

SPECIFICATION Plug socket This invention relates to plug sockets of the kind comprising a face plate in which is formed a pair of spaced apertures through which the pins of an electrical plug can be passed in use to effect electrical connection between the pins and contact elements respectively forming part of the socket.

It is known to provide a shutter mechanism which is located between the base plate and the contact elements and which acts to prevent a screw driver or the like being inserted through an aperture and making contact with a contact element. Sometimes the shutter mechanism is designed so that the insertion of an earth pin of the plug through a further aperture in the face plate moves the shutter mechanism to an inoperative position to allow insertion of the remaining pins of the plug into the pair of apertures. In other forms of shutter mechanism it is the simultaneous insertion of a pair of pins through the holes respectively which allows the shutter mechanism to move to the inoperative position to allow complete insertion of the pins through the apertures.The present invention is concerned with a plug socket having the second form of shutter mechanism and has for its object to provide such a socket in a simple and convenient form.

According to the invention a plug socket comprises a face plate having a pair of apertures formed therein, contact elements mounted relative to the face plate, said contact elements in use being engaged by the pins of a plug engaged with the socket, a shutter mechanism located between the contact elements and the apertures said shutter mechanism comprising a pair of members slidable transversely relative to the axes of the apertures in opposite directions from operative positions in which access to the contact element through the apertures is prevented, to inoperative positions in which access to the contact elements is allowed, inclined surfaces on the members respectively, said inclined surfaces being positioned in the operative positions of the members, beneath the apertures respectively, and interengaging means on the members whereby in the operative positions of the members, the members are prevented from moving laterally away from each other, said interengaging means being released to allow movement of the members to the inoperative positions only upon engagement of said inclined surfaces of the pins of a plug respectively.

An example of a plug socket in accordance with the invention will now be described with reference to the accompanying drawings in which: Figure 1 is a perspective view of a portion of the rear surface of the face plate of the socket with parts removed for the sake of clarity, Figure 2 is a perspective view of parts of the shutter mechanism, Figure 3 shows in part sectional side elevation the parts of the shutter mechanism in the operative position, and Figure 4 is a view similar to Figure 3 showing the shutter mechanism acting to prevent the insertion of one pin only.

Referring to the drawings the plug socket comprises a face plate 10 having a rear surface 11. A pair of apertures 12 extend through the face plate to provide access to the interior of a housing 13, for a pair of pins 14 respectively of a plug shown diagrammatically at 15. The portion of the housing 13 which is illustrated is closed by a cover not shown which mounts a pair of electrical contact elements for engagement by the pins 14 respectively.

The portion of the housing 13 accommodates a shutter mechanism and this comprises a pair of identical members generally indicated at 16 which are located within the housing portion 13. Centrally disposed within the housing portion is a block 17 which is apertured to receive a retaining member such for example as a screw, serving to secure the cover portion of the housing in position.

The members 16 are formed from electrically insulating material and each comprises a longitudinal element 18 which is integrally formed with a lateral element 19. The longitudinal element 18 and the lateral element 19 have a flat undersurface 20 which as will be seen from Figure 1, is the surface of the member 16 which is furthest from the apertures. The upper surface 21 of the longitudinal element 18 is inclined slightly to the surface 20 so that the longitudinal element 18 is of increased height at its end remote from the lateral element 19. The lateral element 19 has a small surface portion 22 which is continuous with the surface 21 but the main portion of the upper surface of the lateral element inclines downwardly towards the surface 20 to provide an inclined surface 23 which when the members 16 are in their operative positions, are disposed behind the apertures 12 respectively.

The end of the longitudinal element 18 remote from the lateral element, is cut away to define a pivot edge 24 which forms an extension of the undersurface 20 and at the opposite end of the longitudinal element there is mounted a peg 25 which acts as a location for one end of a coiled compression spring 26. The centre of the peg 25 is offset from the pivot edge 24 for a reason to be explained.

A portion of the side face of the lateral element 19 removed from the longitudinal element 18, is cut away to define an abutment block 26 which defines an abutment surface 27. Moreover, the side wall of the longitudinal element is cut away to define a recess 28 which accommodates the abutment block of the other member 16. In cutting away the side wall to form the recess, a further abutment surface 29 is formed, this surface extending generally normal to the surface 21 and being engageable, as will be described, by the abutment surface 27 of the other member.

The two members 16 are assembled into the housing with the longitudinal elements 18 being disposed on opposite sides of the block 17 and with the surfaces 21, 22 engaging the adjacent surface of the face plate 11. The interior of the hous ing is shaped so as to define recesses for the springs 26 and support surfaces 30 for the pivot edges 24. When assembled the abutment blocks 27 lie within the recesses 28 and by virtue of the fact that the centres of the pegs 25 are offset from the pivot edges 24, the members are biased about the pivot edges 24 so that the surfaces 21 and 22 are urged into contact with the surface of the face plate 11. In this position, the abutment surface 27 of one of the members faces the abutment surface 29 of the other member.

If the pins 14 of a plug are passed through the apertures 12 respectively they will engage the inclined surfaces 23 and both members will be pivoted about their respective pivot edges. This movement results in the abutment surfaces 27 and 29 of the two members being moved to a clearance position and the reaction of the pins with the inclined surfaces 23 causes lateral movement of the members away from each other against the action of the respective springs thereby allowing the pins to be engaged with the contact elements of the plug. If on the other hand a pin, screw driver or the like is inserted through one of the apertures as shown in Figure 4, only one of the members 16 will pivot and while the abutment surface 27 of that member will move to a position such that it is clear of the abutment surface 29 of the other member, the abutment surface 27 of the other member will not move to a position to clear the abutment surface 29 of the one member. Hence although a lateral force will be applied to the one member by the pin the two members remain locked together so that neither member can move laterally to permit further inward movement of the pin. Access to the contact elements is thereby prevented.

Claims

1. A plug socket comprising a face plate having a pair of apertures formed therein, contact elements mounted relative to the face plate, said contact elements in use being engaged by the pins of a plug engaged with the socket, a shutter mechanism located between the contact elements and the apertures said shutter mechanism comprising a pair of member slidable transversely relative to the axes of the apertures in opposite directions from operative positions in which access to the contact element through the apertures is prevented, to inoperative positions in which access to the contact elements is allowed, inclined surfaces on the members respectively, said inclined surfaces being positioned in the operative positions of the members, beneath the apertures respectively, and interengaging means on the members whereby in the operative positions of the members, the members are prevented from moving laterally away from each other, said interengaging means being released to allow movement of the members to the inoperative positions only upon engagement of said inclined surfaces by the pins of a plug respectively.

2. A plug socket according to Claim 1 including resilient means biasing said members respectively to said operative positions.

3. A plug socket according to Claim 2 in which each of said members defines a pivot edge said pivot edges when the members are in their operative positions engaging under the action of said resilient means, respective support surfaces defined by a housing secured to said face plate, said resilient means also acting to bias the members about said pivot edges so that said inclined surfaces lie adjacent said aperture, whereby a pin or pins engaging the inclined surface or surfaces will initially cause pivotal movement of one or both members about the respective pivot edge.

4. A plug socket according to Claim 3 in which each member defines first and second abutment surfaces positioned adjacent and remote from said pivot edge, the first abutment surface of one member engaging with the second abutment surface of the other member to prevent in the operative position of the members, relative lateral movement of the members, the arrangement being such that if a pin or the like is engaged with the inclined surface of one of the members, the second abutment sur face of the other member will disengage from the first abutment surface of the other member but the first abutment surface of the one member will remain in engagement with the second abutment surface of the other member to prevent lateral movement of the members from their operative positions.

5. A plug socket according to Claim 4 in which said resilient means comprises a pair of coiled compression springs associated with the members respectrively each spring having one end located against a wall of the housing and its other end located on a peg formed integrally with the respective member, said pegs having their centres offset from the pivot edges of the respective members, whereby the members are biased about the pivot edges.

6. A plug socket according to any one of the preceding claims in which each member comprises a longitudinal element and a lateral element formed integrally with the longitudinal element from electrically insulating material, said inclined surface being formed on the lateral element, the two elements having a flat surface remote from the aperture and the longitudinal element having inclined opposite surface whereby the end of the longitudinal element remote from the lateral element has an increased height.

7. A plug socket comprising the combination and arrangement of parts substantially as hereinbefore described with reference to the accompanying drawings.