GB2271223A - Electrical accessory shutter etc - Google Patents

Abstract

There is disclosed an electrical socket and plug combination in which the socket 11 has a pair of electrical contacts 13L accessed by plug pin entries (33L) and the plug has a pair of pins 51L insertable into said entries and the socket has a shutter 40 which normally precludes access to the contacts 13L but which is displaceable to permit access for the pins to positions from which to access the contacts by relative movement of plug and socket transversely of the direction of pin insertion into the entries. The shutter is contained in a well 25 and includes end portions (48L, 48N, figure 1, not shown) which cover the socket entries but are cammed by the pins to move the shutter laterally against spring bias. Preferably the shutter is provided with lower pivots (44A, 44B) such that entry of only a single pin rocks the shutter and causes the end portions (48L, 48N) to lock in well projections 25X, Y to prevent lateral movement of the shutter. Earth pin 51E is of T shaped cross-section and engages a keyhole entry. Non conductive plug projection 51X engages a similar keyhole entry. <IMAGE>

Description

TITLE: ELECTRICAL ACCESSORY SHUTTER ETC.

DESCRIPTION This invention relates to electrical accessories applicable to mains electrical systems, particularly, but not necessarily exclusively, where earth as well as live and neutral plug-in connections are required, and there is safety shielding provided for live and neutral entries to a socket accessory.

Safety shielding of socket entries by a member displaceable by plug pins is commonplace for three-pin/ entry systems, i.e. where an earth connection is provided; and for two-pin/entry systems, i.e. where only live and neutral connections are provided. For three-pin/entry systems, in the United Kingdom, the most common type of safety shield for socket entries that directly register with socket contacts is a shutter member moved from a position above the socket contacts but below and blocking live and neutral socket entries when engaged by a longer earth plug pin entrant the earth socket entry before and so that live and neutral plug pins can then enter the live and neutral socket entries.For two-pin/entry systems, as common in continental European countries, one known type of safety shield for two-entry socket accessories that also have direct registration of socket entries and socket contacts) is a shutter member also positioned below and blocking socket entries, which shutter member requires first to be rocked or tilted by both of plug pins out of latching engagement with one socket entry so as only then to be slidable by the plug pins to open both socket entries together.

Our specific interest, from which this invention arises, is a three-pin/entry system, but one that is compact and does not require either a longer earth pin or direct registration of socket entries and socket contacts, in fact actually specifically permits and requires sliding of a plug over a socket in order to make electrical connections between plug pins and socket contacts after first entry of plug pins into socket entries, particularly as first disclosed in principle in our UK and European Patent Nos GB 2 139 433 and EP 0 125 861.Neither of the aforementioned approaches to safety systems is directly applicable to such a system, whether because adoption of a three-pin/entry system shutter member operated by the earth pin would occupy space militating against desired compactness and introducing complexity (including the earth pin not being longer), or because adoption of a rocking and sliding two-pin/entry shutter member within the sliding paths of plug pins in the socket (of the system that is our specific starting point) again introduces undue complexity, over-long live and neutral pins, and generally seems likely also to militate against compactness.

It is an object of this invention to find a different and practical approach that avoids undue complexity and does not militate against compactness.

According to one aspect of this invention, provision is made for moving a shutter member out of a live and neutral connection blocking position by location and plug pin engagement of the shutter member in a socket accessory at a position or positions misaligned and spaced from all of actual electrical contacts of the socket accessory, preferably a position located between an earth entry and live and neutral socket entries thereof in a threepin/entry system.

According to another aspect of the invention, an electrical plug and socket combination is provided in which the socket has electrical contacts accessed by plug pin entries and the plug has pins insertable into said entries and the socket has a shutter which normally precludes access to the contacts but which is displace able to permit access for the pins to positions from which to access the contacts by relative movement of plug and socket transversely of the direction of pin insertion into the entries.

The shutter may be resiliently biased to its normal position.

The displacement of the shutter may be by a camming action on insertion of the pins into the entries.

The presence of at least two plug pins in their respective entries may be required for shutter displacement. It may be arranged that if only one of said two pins is present the shutter tilts to be locked against displacement.

Current-carrying pins of the plug may be "Ii" -shaped and inserted into respective pin entries of the socket by downward movement of the "L" to displace the shutter and moved to engage their socket contacts by forward movement of the "L".

At least one plug pin may be of stem and head section whereby to engage for said relative transverse movement in a correspondingly sectioned slideway. Said stem and head plug pin may be an earth pin, or may not be an electrical pin.

Said relative transverse movement may involve sliding of mating faces of socket and plug when the pins are inserted into the socket entries.

The plug and socket may, when the plug pins and socket contacts are engaged, be locked against separation in the direction of pin entry into the socket entries.

Such provision could be practical for a system of either three-pin/entry or two-pin/entry types, even if with directly registering socket entries and contacts, but that has initially engaging parts additional to plug pins and direct socket connection entries, which additional parts cooperate for movement of the shutter member, and may include formations of the shutter member and integrally moulded non-conducting formation(s) of the plug, say a further projection or projections therefrom in the same direction as its pins.

However, for a preferred system without registration of socket entries and socket contacts, and requiring sliding of its plugs over its sockets after first entry of plug pins into socket entries (say in order to make electrical connections that can already be at least partially directly shielded by tops of its sockets), the plug pins can be used to displace the shutter member.

Indeed, it is feasible, then, for the shutter member to have a rocking and sliding action not dissimilar to that discussed above as known for two-pin systems, but now not located directly above socket contacts. At least in such implementation, socket assembly and/or shutter member access can be vastly eased and improved by accommodating the shutter member and related parts in a recess in the top of a socket body part, advantageously extending directly between the first pin entry positions (before sliding to make actual electrical connections) with the socket connection contacts beyond the recess and further shielded by a side of the recess.Access to such top-recessaccommodated shutter provisions, as well as assembly, is readily and substantially aided by a cover (also having plug-pin entries) applied over the top of the top-recessed socket body part, at least if that cover is removable, say a snap fit, as can be particularly convenient for exposing clamp screws for making of mains wiring connections to the socket accessory.

Specific implementation for this invention and its various aspects will now be specifically described, by way of example, with reference to the accompanying drawings, in which: Figures lA,B,C are top and bottom plan and sectional views showing details of a shutter member having a rocking and sliding action; Figures 2A,B,C are section and plan views of a socket accessory with eye shutter-member in its upper body part, and a plan view of the socket accessory with a cover part fitted over the shutter member; Figures 3A,B,C,D are plan and sections (B-B, C-C, D-D) of a lower body part of the socket accessory of Figure 2; Figure 4 is another section through the socket accessory of Figures 2 and 3, with a corresponding plug; and Figures 5A,B are perspective views of the plug.

In the drawings, a socket accessory 10 has a lower body part 11 with open-topped compartments 12L,N,E for live, neutral and earth connections to plug coupling contacts 13L,N,E and end entries 14L,N,E for mains wiring.

The contacts 13L,N,E are of spring-clench types and extend from mains connection blocks 15L,N,E of conventional type with through apertures (at 16L,N,E in registration with end entries 14L,N,E) and threaded cross-bores (17L only shown) for clamp screws 18L,N,E. An upper body part 21 closes off the compartments 12L,N,E save for access at (22L only shown) to the clamp screws 18L,N,E and capturing entries 23E,X for earth pin and anchor provisions further referred to below; and, in combination with a cover part 31, presents plug pin entries 33L,N spaced from the blocks 15L,N and contacts 13L,N below and thus to some extent shielded by the top of the upper body part 21.The live and neutral entries 33L,N in the cover part 31 are shown as of narrow slit form in the cover part 31 for taking plug pins (51L,N) of L-shaped blade configuration. The earth plug pin entry 23E is shown as of keyhole form for taking a plug pin (51E) of T-shape with rectangular entry 33E thereto in the cover part 31. The live and neutral entries 33L,N are spaced across the socket body parts 11 and 21, shown generally elongate rectangular in plan, and the earth entry 23E,33E provision is spaced from the live and neutral entries 23L,N along the body parts 11,21.

The cover part 31 having entries 33L,N,E shields the mains wiring clamp screws 18L,N,E. The cover part 31 has snap-fit formations (not shown) that cooperate with upper body part formations (not shown) for easy attachment and removal of the cover part 31, at least using a tool such as a knife or screwdriver blade. It would be equally acceptable for the cover part 31 to be removably secured by other means, such as one or more screws going into the upper or lower body parts 11 and 21.

The socket upper body part 21 is further shown with a top recess or well 25 extending transversely through the positions of live and neutral plug pin entries 33L,N. The recess 25 houses a shutter member 40 and related spring 41.

The recess 25 has an upstanding abutment 25A for one end of the spring 41 located at end wall pip 42 within aperturing 43 of the shutter member 40 that also fits over abutment 25A, and can rock on bottom projections 44A,B of sidewalls 45A,B. It is preferred for the shutter member to snap-fit into the well 25, see lip formations 25L in Figure 2A, hence also providing upper rocking projections 44C,D of its sidewalls 45A,B.

Apertures or indentations (not shown) in the bottom of the recess 25 could serve for latching engagement by bottom pad formations (not shown) of the shutter member 40 when the latter is acted upon only by the spring 41 . An alternative would be to use upper side extensions 46X,Y of ends 46A,B of the shutter member 40 to make alternative latching engagements with upstanding abutments (see 25X,Y in Figure 4) of the well 25, which could be as slottings (see Figure 2B). Such operation would require over-centre action by the spring 41 on the shutter member 40 relative to said latching engagements, i.e. normally to secure one or other of such latching engagements so that the shutter member 40 could slide only when held rocked out of either of such latching engagements.Only when in that state could the shutter member 40 slide in the recess 25 to clear entry of live and neutral plug pins into the socket unit.

However, and as actually shown, it is feasible, and very much in the interests of achieving maximally compact provisions (at least as to height in terms of thickness of the shutter member 40), for the spring 41 to hold the shutter member 40 normally out of any latching engagement, but for anything other than substantially simultaneous presentation of live and neutral plug pins to cause one or other of latching engagements.

The shutter member 40 has upstands 47L,N from its end walls 46A,B that obstruct the live and neutral socket entries 33L,N when the shutter member 40 is acted upon only by the spring 41 and/or is in either of its latching engagements. That could (with the above-mentioned overcentre spring action) be until the shutter member is rocked out of both (in fact, whichever one it is in) latching engagements and slid along the recess 25 against bias from the spring 41. Such rocking out of latching and sliding could be effected by simultaneous engagement of sloped cam surfaces 48L,N by plug pins 51L,N as plug 50 is entered into the socket 10.

However, and as actually shown, the spring 41 holds upper side extensions 46X,Y of ends 46A,B of the shutter member 40 out of latching engagement with upstanding formations 25X,Y of the well 25 unless either of its sloped cam surfaces 48L,N is subjected to attempted entry of object. Only if both of those sloped cam surfaces 48L,N are contacted together (by plug pins) will the shutter member 40 remain free to slide in the well 40 (against bias applied by the spring 41).

It will be appreciated that either of the above indicated over-centre or the illustrated arrangements will secure that the shutter upstands 47L,N are effective to block entries 23L,N even if either has anything poked into it. Effectively, that completes safety shielding of the socket additional to coverage of socket connections and contacts by the upper body part 21 and cover 31, including side walling 25S of its top recess 25.

It is further to be appreciated that a socket accessory having its electrical contacts below and registering with its socket entries could be serviced by a shutter member operated from a spaced position, say by extensions of a plug additional to its contact pins. For example, it would be effective for a shutter member to have extensions going below its socket entries and movable with the shutter to allow access therethrough.

Turning to the plug 50, its L-shaped live and neutral contact pins 51L,N and its T-shaped earth pin 51E have been referred to and are clearly illustrated. Those pins 51L,N,E extend through a base 52 and are firmly secured relative thereto. Also, there are shielded conductive connections between each of the neutral and earth pins 51N,E and connector blocks referenced by their apertures 53N,E and shown in preferred line with live connector block referenced by its aperture 53L across the base 52, as is especially advantageous in making flex, cord or cable connections without cutting component wires to different lengths. There is also shielded conductive connection between the live pin 51L and a spring clip 54X for one end of a fuse 55 whose other end is held in a similar spring clip 54Y secured to the live connector block 53L. A conventional cable clamp 56 is shown at end entry for flex, cord or cable to be connected to the plug. The plug 50 further has a top or cover part 57 that is hinged at 57H to the base 52 and securable by a screw 58 in base hole 52X and a threaded top or cover boss 58S. Snap-fit formations are provided at 59 internally of the top or cover for a spare fuse 55S. A further T-shaped anchor projection is shown at 52X to cooperate with keyhole slot 23X for secure location of the plug 50 in the socket accessory 10.

The actual socket accessory 10 shown, and its plug 50, are of our well-known KLIK type, and the socket accessory 10 is specifically adapted for mounting to spaced flanges 61A,B by way of spaced locating bottom ribs 62A,B broken medially for passage of latching members (only 63A shown) in slots 64A,B. Preferred latching members 63 have inventive merit as they operate in slots 64A,B for pivoting of ears 65 at 65P shown beyond hump 66 in upper cam track 67 and stable location in engaged and disengaged positions by ears 68 on a lower cam track to either side of hump 69 between abutments 71X,Y. Spaced bent limbs 72A,B of each latching member 63 enable stretching and recovery of bent limbs of the latching members at installation and in going over hump 69 between stable engaged and disengaged positions. Release provisions of the latching members include blade-engageable and operable outward extension 74 going opposite to its flange engager 75.

Claims (12)

1. An electrical socket and plug combination in which the socket has electrical contacts accessed by plug pin entries and the plug has pins insertable into said entries and the socket has a shutter which normally precludes access to the contacts but which is displaceable to permit access for the pins to positions from which to access the contacts by relative movement of plug and socket transversely of the direction of pin insertion into the entries.

2. A combination according to claim 1, in which the shutter is resiliently biased to its normal position.

3. A combination according to claim 1 or claim 2, in which the displacement of the shutter is by a camming action on insertion of the pins into the entries.

4. A combination according to any one of claims 1 to 3, in which the presence of at least two plug pins in their respective entries is required for shutter displacement.

5. A combination according to claim 4, in which if only one of said two pins is present the shutter tilts to be locked against displacement.

6. A combination according to any one of claims 1 to 5, in which current-carrying pins of the plug are "L"-shaped and inserted into respective pin entries of the socket by downward movement of the "L" to displace the shutter and moved to engage their socket contacts by forward movement of the "L".

7. A combination according to any one of claims 1 to 6, in which at least one plug pin is of stem and head section whereby to engage for said relative transverse movement in a correspondingly sectioned slideway.

8. A combination according to claim 7, in which the stem and head section is a T-section.

9. A combination according to claim 7 or claim 8, in which said or a stem and head plug pin is an earth pin.

10. A combination according to claim 7, claim 8 or claim 9, in which said or a stem and head plug pin is not an electrical pin.

11. A combination according to any one of claims 1 to 10, in which said relative transverse movement involves relative sliding of mating faces of socket and plug when the pins are inserted into the socket entries.

12. A combination according to any one of claims 1 to 11, in which the plug and socket are, when the plug pins and socket contacts are engaged, locked against separation in the direction of pin entry into the socket entries.