This invention relates to a socket connector for connecting with the pins of an electrical plug.

The invention relates in particular, though not exclusively, to a socket connector for a socket and plug assembly in which at least one of the socket and plug is at the end of a flexible type conductor which inadvertently might impose a force on the assembly and result on disconnection of the socket and plug.

To provide secure connection between the connector and plug, and thus resist inadvertent separation, it is well known to provide a locking mechanism that resists separation until a release means is operated to permit separation of the socket and plug.

Examples of known electrical socket connectors with a locking mechanism operable to allow separation of a socket and plug are described in EP

1459412A and US 7484986B.

For electrical sockets that comply with the standard NEMA 1 -15P the locking mechanism of US 748986 is particularly suitable. That locking mechanism takes advantage of the feature of the pins of a plug in accordance with the NEMA standard that the pins are each provided with apertures. US 7484986 describes an arrangement in which locking bolts are movable to enter the pin apertures but may be withdrawn to allow release of the plug pins from the socket.

The arrangement of US 7484986 however has the disadvantage of not being convenient in use, especially when seeking to release the locking mechanism. Each of the pair of apertured pins is locked by a bolt under the control of an associated release button. Thus to effect release of the locking mechanism it is necessary simultaneously to press the two button concurrently with a user applying a force to separate the socket and plug. Particularly for sockets located at a position of restricted access, such as at the rear of a bank of electrical devices, that simultaneous depression of the two buttons concurrent with separation of the socket and plug often is difficult.

A further disadvantage of a socket such as that of US 7484986 is that of the cost of the component parts.

The present invention seeks to provide an improved electrical socket connector which is particularly suitable for retention of plug pins of a type provided with retention apertures.

In accordance with one aspect of the present invention there is provided a socket connector comprising a housing having at a first end an end face which defines at least two end face apertures through each of which the pins of a plug may be inserted, the housing having a second end at which an electrical conductor may extend to a chamber within the housing, said chamber having positioned therein at least two electrical terminals, each electrical terminal being located to receive a plug pin inserted through a respective one of the end face apertures and each terminal comprising a pair of arms, a first arm and a second arm, which at least in part are spaced apart at that end of the terminal closest to said end face of the housing for receiving an inserted pin, said arms being secured to one another at the other end of the terminal for electrical contact with a conductor extending through the second end of the connector housing at least a first arm being a flexible arm able to deflect in a direction substantially perpendicular to the direction of pin insertion and to bear resiliency against an inserted pin, the first arm of at least one of the electrical terminals comprising a locking projection which is operable to engage with the aperture of an inserted pin and thereby resist removal of the plug when the plug is engaged with said connector, the two terminals being spaced apart and having positioned therebetween a control member which is slidable in a direction between said first end and said second end of the housing, said control member comprising an actuation surface and at least one of the electrical terminals comprising a deflector which extends between the actuation surface of the control member and the first arm whereby, in use, movement of the actuation surface forces the first arm to deflect away from the second arm, and the socket comprising biasing means provided within the housing to bias the control member to a first position at which the deflector does not deflect the first arm, whereby the locking projection is able to reside in the pin aperture, and a second position at which the deflector moves the first arm to a position away from the second arm whereby the locking projection is withdrawn from the pin aperture.

The actuation surface may be a cam surface. The deflector may be arranged to slide over the cam surface. The actuation surface may bear against a deflector orientated to cause the first arm to deflect away from the second arm of a terminal without any relative sliding of the actuation surface and the deflector. The actuation surface may be in contact with the deflector at all positions of the control member or only when the control member is moved from a position at which the locking projection is positioned to engage in a pin aperture.

The first arm of at least one of the electrical terminals may be positioned closer to an internal wall of the housing than the second arm, the two second arms of the two electrical terminals may be spaced apart to provide space, therebetween for the control member which is slidable in a direction between said first end and the second end of the housing.

In the aforementioned configuration, referred to hereinafter as Configuration A, a control member is movable against the bias force to urge the first arm of the terminal in a direction further towards the wall of the housing and thus away from the second arm of the terminal.

Alternatively, however, the second arm may be closer to the wall of the housing than the first arm of the terminal. In that configuration, referred to hereinafter as Configuration B, a control member is arranged to be movable against the bias force to urge the first arm of the terminal to a position further away from said wall of the housing and thus away from the second arm of the terminal.

In the Configuration A the deflector extending from the first arm of a terminal may extend alongside one or each of the longitudinal edges of the second arm of the terminal for engagement with a cam or other actuation surface. Alternatively the second arm may be provided with a deflector aperture through which the deflector may extend for engagement with the cam or other actuation surface.

Movement of the control member against the bias means may be by means of a slider connected to or integral with the control member. The slider may extend through the housing wall at a position between the first and second ends of the housing. The housing may comprise an elongate slot extending longitudinally between said ends of the housing and through which the slider extends to be slidable in said longitudinal direction. The slider may be integral with or secured to a handle formation that extends externally of the housing. The handle may extend at least partially around the periphery of the housing. Thus for a housing of substantially square or rectangular shape the handle may extend over three side regions or may extend wholly over all four sides.

The biasing means may be a metal spring, for example a coil spring.

Preferably the coil spring is arranged to be compressed in length when the slider and control member move to deflect the first arm of the or each terminal to a release position.

Within the housing the terminals may be provided with tabs or screw

connectors for receiving the ends of electrical conductors, such as conductors within a flexible cable.

The socket may be of a type having only two pin receiving apertures.

Alternatively it may have one or more additional pin receiving apertures, for example one for receiving an earth pin, and an electrical terminal may be associated with each additional aperture. Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:-

Figure 1 is a perspective view of a socket connector in accordance with the present invention;

Figure 2 is an assembly of the socket of Figure 1 with a plug secured thereto;

Figure 3 is a sectional view of the socket of Figure 1 with an upper part of the housing removed;

Figure 4 corresponds substantially with Figure 3 but with the cam and control member removed;

Figure 5 is a detailed perspective view of and electrical terminal of the socket of Figures 1 to 4;

Figure 6 is a perspective view of the assembly of Figure 2 with an upper part of the socket housing removed;

Figure 7 is a sectional view, perpendicular to the plane of Figure 3, and on the line A-A of Figure 3, of the assembly of Figure 2;

Figure 8 is a diagrammatic view of a control member of Configuration B and in accordance with a second embodiment of the present invention, and

Figures 9a and 9b show a variation of Configuration B of Figure 8 respectively in locked and unlocked position.

An electrical socket 10 in accordance with the standard NEMA 1 -15P (2PIN) comprises a two part housing 11 comprising a base section 12 and an upper section 13 which are bonded or screwed together subsequent to assembly of components in a chamber 14 defined within the housing.

A first end 15 of the housing comprises an end face 16 which defines two pin receiving apertures 17. The other end 18 comprises a cable entry 19 and associated cable guide 20.

The socket housing is of a substantially rectangular cross sectional shape and three sides of the housing provide in part guidance for a handle 25 which is slidable longitudinally in a direction between the first and second ends of the housing.

The chamber 14 within the housing provides support, in known manner, for two terminals 26. Each terminal comprises two arms 27, 28 which define, at an outer end 29 of the terminal, a pin receiving region 30 aligned with a pin receiving aperture 17 of the end face.

The arms are connected together at the inner end 31 of the terminal, in electrical contact with a tab section 32 to which a cable conductor may be secured in a conventional manner.

One of the arms, a first arm 27 of each terminal 26 is provided with a locking bolt 36 that projects towards the other arm 28 and is positioned along the length of the terminal such that , in use, it engages in conventional manner with an aperture 40 of an inserted pin 41 , thereby inhibiting separation of the assembled plug and socket. The first arm 27 is deflectable in a direction perpendicular to the length of the arm and is positioned in the aforementioned Configuration A.

Release of a plug is facilitated by means of the external handle 25 which is in engagement with the head portion of a spring biased cam 45 positioned within the housing, between the two terminals 26. The cam comprises two cam surfaces 46 each inclined relative to the length direction of the terminals and is biased to a first position as shown in Figure 3 by means of a helical compression spring 47. The cam comprises a head portion 48 which is secured to an aperture 49 in the handle 25 whereby the cam surface is movable in the longitudinal direction under the action of the slidable handle.

Each terminal first arm 27 comprises a deflector element 50 that extends, through an aperture in the second arm 28 towards the cam surface 46. The length of the deflector is such that when the cam is in the first position (see Figure 3) the distal end of the deflector bears only slightly on the cam surface. However as the handle is slid against the biasing action of the compression spring the deflectors and thus the terminal arms 27 are moved outwards under the cam action, each arm 27 thus being deflected away from the associated second arm 28. In consequence the locking bolt 36 is moved away from the second arm and in particular is withdrawn from the aperture of an inserted pin whereby that pin may be freely removed from the socket.

In a second embodiment of the present invention, see Figure 8, the cam 45 is replaced by a cam 60 having inwardly facing cam surfaces 61. In this construction, of Configuration B, the deflectable first arm 62 lies closer to the cam than the associated second arm 63. The deflector 65 extends over an upper surface of the cam to engage at end region 66 with the inclined cam surface 61 and thus, as in respect of the first embodiment of the invention, sliding of the cam under the action of the external handle effects separation of the arms of each terminal and withdrawal of the locking projection 64 from an inserted pin.

In a variation shown in Figures 9a and 9b of the Configuration B of Figure 8 the actuation surfaces 61” and confronting end regions 66” of the deflectors are arranged such that movement of the terminals to an open position is primarily by a small longitudinal movement of the end regions 66” with only a small sliding movement, if any, over the cam surfaces. Figures 9a and 9b show the terminals respectively in a locked, closed position and an unlocked, open position. The actuation surface 61” of the control member 60” is at an angle of at least 60 degrees to the longitudinal direction of movement of the cam and that surface causes deflection of the deflector when engaged and moved longitudinally over a short distance by the cam surface 61”. When the terminals are in a locked position the actuation surface and deflector end regions are spaced apart but they come into engagement as the control member is moved against the biasing force of the bias means.

In contrast to the prior art constructions of a socket connector in accordance with the standard NEMA 1-15P the present invention provides a socket which is more convenient in use. Furthermore the need to provide two springs and two external buttons is avoided.