GB2238185A

GB2238185A - Electrical plug

Info

Publication number: GB2238185A
Application number: GB9021615A
Authority: GB
Inventors: Haim Hadar
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-10-09
Filing date: 1990-10-04
Publication date: 1991-05-22
Anticipated expiration: 2010-10-04
Also published as: GB2238185B; GB9021615D0; AU6392190A; AU652921B2

Abstract

An electrical plug (10) comprises a main body (12) and a cover (14) which are both generally triangular in plan. The plug pins (16) are secured to the base wall (18) of the main body. Side walls (20) slope upwardly and there are overhanging lips (22) along the two longer edges of the main body. The cover (14) slides into position beneath the lips (22) and has on the underside a protrusion (40) with flanges (42) which fit in grooves (38) of two blocks (24) integral with the wall (18). The outer surfaces of the walls (20) can be gripped to enable the plug pins (16) to be pulled from an electrical socket. This pulling action cannot separate the main body (12) from the cover (14). A cable (C) lies on a ramp (54) on the wall (18) and is gripped by an inclined flexible clamping plate (58) mounted in a groove (56) in the lid. A second groove (56) is provided for the plate (58) to enable it to grip a thinner cable. <IMAGE>

Description

ELECTRICAL PLUG THIS INVENTION relates to electrical plugs.

According to the present invention there is provided an electrical plug comprising a main body, electrically conductive plug pins secured to said main body and protruding therefrom, means for securing bared electrical conductors to said pins, the main body being open on one side so that access can be had to said means, a cover which, when fitted to the main body, closes-off the open side of the main body and conceals said means, and external surfaces by means of which the plug can be gripped for the purpose of pulling said plug pins from an electrical socket without exerting any force on the body and the cover which tends to separate the body and the cover.

In the preferred form said main body is upwardly open with said pins protruding downwardly from the main body through a base wall thereof, and said cover slides transversely of the axes of the plug pins into guides of the main body to close-off the upwardly open main body, said surfaces being on the main body.

The plug can further include a cable clamp comprising a first surface on said main body and a second surface on said cover, said surfaces moving into co-operating relationship to grip an electrical cable between them as the cover is slid to its closed position. Preferably said first surface is in the form of a ramp and said second surface is the edge of an inclined flexible plate, the sloping face of said ramp and the edge of the plate defining a cable receiving gap between them.

The means for connecting the cover and main body preferably includes a flexible catch on the underside of said cover which engages with a locking member of said main body as the cover is slid onto the main body thereby to secure the cover to the body. To able the plug to be opened there can be an opening in the main body through which access can be had to said catch so that the catch can be disengaged from said locking member to permit the cover to be removed.

For a better understanding of the present invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings in which: Figure 1 is a pictorial view of the underside of an electrical plug; Figure 2 is a pictorial view of the top of the plug of Figure 1; Figure 3 illustrates the plug with a cover partly removed; Figure 4 is a transverse section through the plug; Figure 5 illustrates a modification of the plug; Figure 6 illustrates the means for connecting a cover of the plug to the body of the plug; and Figure 7 illustrates a cable clamp.

The electrical plug illustrated is generally designated 10. The plug 10 comprises an injection moulded main body 12 and an injection moulded cover 14.

In the form illustrated the plug has three pins designated 16. The pins 16 are moulded into the main body 12. Thus, in production, the three pins 16 are located so that part of the length of each of them is within the mould. These parts can be serrated or otherwise formed so that there is an interlock between each plug pin and the moulded main body so that the pins cannot be pulled out of the main body. Each pin is of electrically conductive metal and has a transverse bore (not shown) therethrough for receiving the bared end of one of the wires of an electric cable.

A tapped bore (not shown) intersects the bore which receives the bared electrical wire and a grub screw (not shown) in this bore clamps the bared electrical wire to the pin.

The main body 12 incorporates means for clamping the electrical cable so that, if it is pulled, the bared wires do not come out of the bores in the pins. A preferred form of clamp is described hereinafter with reference to Figure 7. However it is also possible for the cable clamp to be of conventional form and comprise a flexible bridge of material and two screws which pass through the ends of the bridge and into the main body 12. When the screws are tightened, the bridge is bowed and clamped onto the cable.

Alternatively, the cable grip can comprise two plates which are arranged in a V-formation with a gap between their adjacent ends. The gap is narrower than the diameter of the cable. The cable is pressed downwardly between the plates and distorts the plates somewhat.

Provided some slack is left in the cable between the portion of the cable which is gripped by the two angled plates and the location at which the bared wires are connected to the plug pins 16, a pull on the cable merely causes the plates to clamp the cable more tightly and prevent taking-up of the slack between the plates and the plug pins. The advantage of the clamp of Figure 7 over the two forms just described is that it is automatically brought into use as the cover 14 is closed.

The electrically conductive pins 16 protrude from the base wall 18 of the body 12. The main body 12 includes a side wall 20 which slopes outwardly from the base wall 18, there being an inwardly protruding lip 22 along two of the edges of the generally triangular main body 12.

The main body 12 further includes two integrally moulded blocks 24 which protrude upwardly from the base wall 18. Each block 24 has a groove 26 therein. The cable C (shown in dotted lines in Figure 2) enters the upwardly open main body through a gap in the rear section of the side wall 20. The gap is bounded by the blocks 24.

The cover 14 includes a generally triangular plate 28 which has ridges 30 moulded thereon to enable the cover 14 readily to be slid, with respect to the body 12, in the direction of the double headed arrow A in Figure 3. The direction of sliding is transverse to the axes of the pins 16.

On the underside of the plate 14 there is a protrusion 32 which is shaped so that it slides in the dovetail which is constituted by the grooves 26.

Protruding downwardly from the rear edge of the plate 28 is a closure element 34 which has therein an arch 36 through which the electrical cable C passes.

When the cover 14 is fitted to the main body, as shown in Figure 2, the element 34 lies in, and closes, the gap in the side wall 20.

In use of the plug, the electrical cable C is connected to the pins 16 whilst the cover 14 is removed. The cable is then clamped by which ever of the above described means has been provided for this purpose. The cable runs out of the main body 12 between the blocks 24 and through the arch 36 as indicated in dotted lines in Figure 2.

The cover 14 is presented to the main body 12 in such manner that the protrusion 32 enters the grooves 26, the cover 14 then being slid forwardly towards the apex of the main body 12. The edges of the plate 28 are, when the cover 14 is in position, beneath the lips 22.

In Figure 5 there is illustrated a plug which is similar to that illustrated in Figure 4 except in that the dovetail grooves 26 are replaced by rectangular grooves 38 and the protrusion 32 is replaced by a protrusion 40 which has flanges 42 along the edges thereof which flanges enter the grooves 38.

Turning now to Figure 6, this illustrates the means which attach the cover 14 to the body 12.

Protruding upwardly from the base wall 18 is a column 44. Adjacent the column 44 there is an opening 46 in the base wall 18 (see also Figure 1). On the underside of the cover 14 there is a flexible catch 48 which has a curved cam face 50. In the lower edge of the catch 48 there is a notch 52.

As the cover 14 is slid into place on the main body 12, the cam face 50 encounters the top of the column 44 and the catch 48 is deflected upwardly. When the top of the column 44 comes into register with the notch 52, the catch 48 returns to its undeflected condition with the top of the column 44 in the notch 52, as illustrated in Figure 6, and the cover 14 cannot then be moved with respect to the body 12. To open the plug an instrument such as a screwdriver must be inserted into the plug through the opening 46 to lift the catch 48, whilst simultaneously the cover 14 must be slid towards the open position.

The cable clamp of Figure 7 comprises, on the top face of the base wall 18 and between the blocks 24, a ramp generally indicated at 54. The ramp slopes upwardly in the direction away from the opening in the rear section of the side wall 20. On the underside of the cover 14 there are two grooves 56 which form mountings for the upper edge of an inclined flexible clamping plate 58 which is slid from the side into the groove. The plate 58, when the cover 14 is in its closed position, defines between itself and the ramp 54, a gap 60 through which the cable C passes. Each plate 58 and each groove 56 tapers so that the plates 58 cannot drop out of the grooves 56.

Once the cable C has been connected to the pins 16 it is pressed down into the gap between the blocks 24 so that it lies on the ramp 54. As the cover 14 is slid to its closed position, the lower edge of the plate 58 bears on the cable C thus gripping it between the ramp 54 and the plate 58. The lower edge of the plate 58, and also the ramp 54, can be serrated to enhance the gripping action.

If a thinner cable than that illustrated is used, then the plate 58 is moved to the other groove 56, the gap 60 between a plate in the front groove 56 and the ramp 54 being smaller.

When the plug are pulled from a socket, it is gripped by means of the outer surfaces of the walls 20.

Thus no pull is exerted which can separate the cover 14 and main body 12 and thereby accidentally uncover the "live" parts of the plug. If desired an external rib 62, see Figure 4, can be provided on the body 12 so as to make it easier to grip the body.

Whilst round section pins 16 have been illustrated, and the body 12 has been shown as generally triangular in plan view, it will be understood that the pins 16 could be of any other cross section, e.g. rectangular, the body 12 could be of other shapes when viewed in plan, and the pins 16 could be arranged other than at the apices of a triangle.

The blocks 24 support the cover 14, which is relatively thin and flexible, and prevent it being bowed inwardly if a downward force is exerted on the top face thereof. This is best seen in Figures 4, 5 and 7.

If desired the means illustrated in Figure 6 can be replaced by a screw which passes upwardly through a hole in the base wall 18 and into a thickened part of the cover 14.

The plug illustrated can be opened, a cable secured thereto, and reclosed rapidly. The only tool needed is a screw driver which is used to lift the catch 48 and then to tighten the screws which attach the bared wires to the pins 16.

Claims

CLAIMS:

1. An electrical plug comprising a main body, electrically conductive plug pins secured to said main body and protruding therefrom, means for securing bared electrical conductors to said pins, the main body being open on one side so that access can be had to said means, a cover which, when fitted to the main body, closes-off the open side of the main body and conceals said means, and external surfaces by means of which the plug can be gripped for the purpose of pulling said plug pins from an electrical socket without exerting any force on the body and the cover which tends to separate the body and the cover.

2. An electrical plug as claimed in claim 1, wherein said main body is upwardly open with said pins protruding downwardly from the main body through a base wall thereof, and said cover slides transversely of the axes of the plug pins into guides of the main body to close-off the upwardly open main body, said surfaces being on the main body.

3. A plug as claimed in claim 2 and including a cable clamp comprising a first surface on said main body and a second surface on said cover, said surfaces moving into co-operating relationship to grip an electrical cable between them as the cover is slid to its closed position.

4. A plug as claimed in claim 3, wherein said first surface is in the form of a ramp and said second surface is the edge of an inclined flexible plate, the sloping face of said ramp and the edge of the plate defining a cable receiving gap between them.

5. A plug as claimed in claim 4, and including first and second mountings for said plate, said gap being smaller when the plate is carried by one mounting than when it is carried by the other.

6. A plug as claimed in claim 2, 3, or 5 and including a flexible catch on the underside of said cover which engages with a locking member of said main body as the cover is slid onto the main body thereby to secure the cover to the body.

7. A plug as claimed in claim 6, wherein there is an opening in the main body through which access can be had to said catch so that the catch can be disengaged from said locking member to permit the cover to be removed.

8. An electrical plug substantially as hereinbefore described with reference to the accompanying drawings.