GB2203603A

GB2203603A - Electric plugs

Info

Publication number: GB2203603A
Application number: GB08807906A
Authority: GB
Inventors: Alun Clive Owen
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-04-04
Filing date: 1988-04-05
Publication date: 1988-10-19
Anticipated expiration: 2008-04-05
Also published as: GB8708105D0; GB8807906D0; GB2203603B

Abstract

The plug 10, which is a three pin electric plug, comprises a base 12, a cap 14, and pins 16, 18, 20 by means of which the plug may be engaged in an electrical socket. The base 12 has disposed therein three separate channels 22, 24, 26, each of which receives one of the three insulated leads 40, 42, 44 to the plug. In each channel are spikes 28 capable of piercing the insulation of the respective lead, the formations in each separate channel being electrically connected to a respective one of the pins. The cap member 14 is engageable with the base member 12 in such a way that the insulated leads are pressed by the cap member into contact with the spikes 28 so as to be pierced thereby. <IMAGE>

Description

Electric Plugs The present invention is concerned with electric plugs, and in particular three-pin electric plugs of the type used for domestic electrical appliances.

Three-pin plugs for such appliances conventionally comprise a pair of casing members secured together by at least one screw; each of the three leads is typically connected to the respective pin by means of a screw and there are often screws to retain the cable in position. Many people find it difficult to manipulate such small screws and it is often irksome for the user to have to find a suitable screwdriver.

Various proposals have been made to simplify the assembly of such three-pin plugs, but often a screwdriver is still required and it is sometimes necessary to crimp conductor portions around the leads, which necessitates use of pliers.

I have now devised an improved three-pin plug in which the way in which the leads are connected is simplified.

According to the present invention, there is provided a three-pin electric plug which comprises a base member, a cap member, and pins by means of which the plug may be engaged in an electrical socket, the base member having disposed therein three separate channels, each of which channels being shaped and dimensioned to receive an individual one of the three insulated leads to the plug and provided with piercing means capable of piercing the insulation of the respective lead, said piercing means in each channel being electrically connected to,a respective one of said pins, the cap member being engageable with the base member in such a way that the insulated leads are pressed into contact with said piercing means to be pierced thereby.

Preferably the cap member is secured to the base member without the use of screws; for example, the cap member may be secured to the base member by clip means which is such that the plug may be assembled completely without the use of a screwdriver. In one embodiment, the cap member and the base member may be pivotally interconnected. Alternatively, the cap member may be secured to the base member by interengaging complementary slide formations on the base member and cap member. In either case, it is preferred that locking means be provided so as to lock said cap member to said base member when the plug is fully assembled and prevent inadvertent detachment of the cap member from the cap member when the plug is installed in an electrical socket.

As with conventional three-pin plugs, at least one fuse holder and corresponding fuse may be provided connected between the channel carrying the 'live' lead and the 'live' pin. Advantageously, the plug is provided with a cord grip and, once again, it is preferred that this should be of the frictional gripping type rather than screw operated.

The conductors are preferably made of copper or brass, the pins of brass, and the body moulded from plastics material; all of these are as for conventional three-pin plugs.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a top plan view of a base member of an exemplary plug according to the invention; Figure 2 is a partial sectional view taken on line II-II of Figure 1; Figure 2a is a similar view to Figure 2 of a slightly modified arrangement; Figure 3 is a partial plan view of a modification of the plug shown in Figure 1; Figure 4 is an underneath plan view of a cap member for cooperation with the base member of Figure 1; Figure 5 is a sectional view taken on lines \ of Figure 4; and Figure 6 is an exploded perspective view of the complete plug corresponding to Figure 1.

Referring to the drawings, and in particular to Figures 1, 2, 4, 5 and 6, a three-pin electrical plug generally designated 10 for connecting domestic appliances to the electric mains supply comprises a base member 12 and a cap member 14. The base member 12 carries electrical connector pins 16, 18, 20 for engaging in an electrical mains outlet socket and connecting to the live, neutral and earth terminals respectively. Within the base member 12 are disposed three separate channels 22, 24, 26 connected respectively to the live, neutral and earth pins 16, 18, 20. The channels 22, 24, 26 contain one or more spikes 28 of a conducting material, for example copper. The spikes 28 in each of the channels are connected by means of copper conductors 30 to their respective pins.In the case of the channel 22, which is for receiving the 'live' lead, the connection to the pin 16 is via a fuse holder 32 carrying a cartridge fuse 34. A cable grip 36 is provided of the frictional engagement type to secure the electrical cable 38. The latter comprises three individual leads 40, 42, 44 for live, neutral and earth, respectively.

Figure 2A illustrates another form of the channels 22, 24, 26 in which the spikes 28 are arranged in pairs with the points directed towards one another.

As can be seen from Figure 4, the cap member is of the same general shape as the base member and is designed to cooperate therewith. The cap member carries three channels 46, 48, 50 complementary to the channels 22, 24, 26 in the base member. Each of the channels 46, 48, 50 is provided with a series of depressions 52 corresponding to the position of the spikes 28 on the base member 12.

In order to secure the base and cap members together, means may be provided such as a projection 54 on the base member and a complementary depression 56 on the cap member whereby the two components may be a 'snap-fit'.

Other means of engagement of the cap member to the base member may be employed. It is preferable to provide means whereby the cap member cannot readily be removed from the base member when the latter is in place in an electrical socket, for example, complementary projections and channels whereby the cap member slides laterally onto and engages with the base member. Other means of penetration of the leads may also be employed, such as one or more blades disposed in each channel and electrically connected to a respective pin.

Figure 3 illustrates a different spatial location of the channels 22, 24, 26 which receive the leads 40, 42,44.

In use, the cable 38 is stripped of external insulation exposing the leads 40, 42, 44. The length of lead exposed should correspond with the length of the channels 22, 24, 26. The insulation does not need to be stripped, and indeed is preferably not stripped, from the leads 40, 42, 44.

lhe latter are placed in their respective channels 22, 24, 26 and the cable gripped by means of the cable grip 36. The cap is then placed in engagement with the base member causing the undersides of the channels 46, 48, 50 to press downwardly on the respective leads 40, 42, 44 and ensuring that the spikes 28 penetrate the insulation of the lead and make a good electrical connection to the conductors within. Disassembly of the device is a simple reversal of the above procedure, in which the cap member is disengaged from the base member after which the leads may be removed from their channels in a very simple manner.

The electrical plug according to the invention can be assembled and taken apart without the need for screwdriver or pliers or indeed any tools apart from a blade if the insulation on the cable 38 needs trimming back.

Claims

CLAIMS:

1. A three pin electric plug, which comprises a base member, a cap member, and pins by means of which the plug may be engaged in an electrical socket, the base member having disposed therein three separate channels, each of which channels being shaped and dimensioned to receive an individual one of the three insulated leads to the plug and provided with piercing means capable of piercing the insulation of the respective lead, said piercing means in each channel being electrically connected to a respective one of said pins, the cap member being engageable with the base member in such a way that the insulated leads are pressed by said cap member into contact with said piercing means to be pierced thereby.

2. A plug according to claim 1, in which said cap member is such that it can be secured to said base member by means not involving the use of screws.

3. A plug according to claim 2, in which said cap member is pivotally connected to said base member.

4. A plug according to claim 2 or 3, in which said cap member is a snap fit on said base member.

5. A plug according to claim 2, in which said cap member and base member are provided with complementary projections and channels whereby the cap member can be slid laterally on tosaid base member for engagement therewith.

6. A plug according to any of claims 1 to 5, in which said piercing means comprises at least one spike in each said channel.

7. A plug according to claim 6, in which at least one depression is provided in said cap member, in complementary location relative to said at least one spike.

8. A plug according to any of claims 1 to 7, in which said cap member incorporates three channels in complementary location relative to said channels provided in said base member.

9. A three pin electric plug substantially as described herein with reference to Figures 1, 2 and 4 to 6 of the accompanying drawings, or with reference to said drawings as modified by either Figure 2a or Figure 3 of the accompanying drawings.