GB2056189A

GB2056189A - Improvements in or relating to electrical plug devices

Info

Publication number: GB2056189A
Application number: GB7927747A
Authority: GB
Original assignee: MARBOURN Ltd
Current assignee: MARBOURN Ltd
Priority date: 1979-08-09
Filing date: 1979-08-09
Publication date: 1981-03-11
Also published as: GB2056189B

Abstract

In an electrical plug, with a multiplicity of pins, at least two of the pins (e.g. 14, 15) have regions of reduced cross-section around which are located insulating sleeve members (20, 21), each sleeve member being fixed by joining together abutting edges extending along the pins. <IMAGE>

Description

SPECIFICATION Improvements in or relating to electrical plug devices The invention relates to an electrical plug device. In this specification an electrical plug device comprises a plug-in coupling device for use in providing an electrical supply, such as an electrical plug or a piug-in adapter.

The invention is particularly applicable to electrical plug devices for use in domestic and other wiring systems. The term "plug devices" is applicable to multi-pin plugs as well as single-way or multi-way adapters.

It is an object of the invention to improve the safety of a person inserting an electrical plug device into, or withdrawing it from, a socket by providing an improved insulating protective covering to part of at least some of the pins of the plug device.

The present invention provides an electrical plug device comprising an insulating body member, a plurality of projecting pins for conducting electrical current, at least two of the pins having a region of reduced cross section spaced from the free end of the pins and insulating sleeve members secured around the pins in said regions of reduced cross section, each sleeve member being fixed in position by joining together abutting edges extending along the pins.

Preferably each sleeve member is formed in two or more parts, the parts being joined together when located in position around the regions of reduced cross section. The parts may be joined by welding, ultrasonic techniques, fusion, cold welding or bonding using an adhesive or other suitable chemical.

Alternatively each sleeve member may be formed in one piece. In such a case the sleeve member may be formed with one joint along the length of the sleeve member, the edges of the joint being secured together by any one of the techniques described above.

Commonly the pins have a rectangular cross section. In some alternative cases the pins may have a round cross section. Preferably each sleeve member is made in two parts joined together along edges extending parallel to the length of the pins. Normally pins of rectangular cross section have a short size and a long side. The join in each insulating member may be located on a short side of a rectangular pin or alternatively on a long side.

Alternatively the or each join in a sleeve member may be located along a corner joining two sides of a rectangular pin.

One embodiment of the invention will now be described by way of example and with reference to the accompanying drawings in which: Figure 1 shows a perspective view of an electrical plug device, Figure 2 is an exploded view of one electrically conducting pin of the plug device together with two halves of an insulating sleeve member, and Figure 3 is a perspective view of the arrangement shown in Figure 1 with the sleeve member joined together in position on the pin.

The particular example shown in Figure 1 comprises a 1 3 amp electrical plug intended for use in a domestic electrical supply circuit. The plug comprises an electrically insulating base 11 together with electrically insulating cover 12.

Three rectangular pins 13, 14 and 1 5 project from the base and are arranged for insertion into a socket device. The pin 13 comprises an earth pin.

The pins 14 and 1 5 are intended for connection to line and neutral. Each of the pins is of flat rectangular form having a long side and a short side. As the pin 13 is intended for earthing purposes there is no need to provide special insulation on the pin. However, as the pins 14 and 1 5 are to be connected into the supply circuit, each is provided with an insulating sleeve in accordance with the present invention. Figure 2 shows the arrangement used for the pin 14 and it is to be understood that pin 1 5 is similarly constructed. As is shown in Figure 2, the pin, which is made of electrically conducting material, has a tapered free end 1 6 of suitable dimensions to enter the mating electrical socket.The other end 1 7 is formed with an enlarged head for mounting within the body of the plug device so that the pin projects through an aperture in the base 11 while the head of the pin is retained in position within the plug. A region 1 8 of the pin which is spaced from the free end 16, is formed of reduced cross section and normally lies adjacent the base 11 of the plug and projecting outwardly therefrom. The insulating sleeve member is formed in two halves 20 and 21 as shown in Figure 2. Each part of the sleeve member is of rectangular channel form and is arranged to fit around the region 18 of reduced cross section on the pin 14.The edges 22 on each part of the sleeve member are arranged to abut the corresponding edges of the other part of the sleeve member and thereby form a line contact extending parallel to the length of the pin 14 and in the particular case shown in Figure 2 the join line extends midway along the short side of each pin. The dimensions of the two parts of the insulating sleeve are such that they fit exactly into the region 1 8 completely insulating the pin over the length of the region 1 8 and they fill the recessed region so that the external surface of the insulating sleeve then lies flush with the remainder of the pin 14. Once the two halves of the insulating member have been located in position, they are joined together by welding, or by ultrasonic techniques, or by fusion, cold welding or bonding using an adhesive or other suitable chemical.Once joined together they occupy the position shown in Figure 3. It can be seen that the portion of the current carrying pins nearest the plug body is thereby insulated so that when a person inserts the plug into a socket the finger of the operator cannot come into contact with a metallic part of the pin once the pin touches the electrical contacts in the socket and before the pin is pushed fully into position in the socket.

Although the above example has shown a domestic 13 amp plug, it will be appreciated that the invention is applicable to other plugs as well as multi-way or single-way adapters provided they have current carrying pins for location in a socket member. In particular the invention may be applied to two or three pin plug devices and they may have round pins or rectangular pins. Although in Figures 2 and 3 the join in the insulating member extends along the length of the pin midway across the short side of each pin, the joins may be located on the long side of the rectangular pins or alternatively along the corners at the junction of the long and short sides.

Claims

1. An electrical plug device comprising an insulating body member, a plurality of projecting pins for conducting electrical current, at least two of the pins having a region of reduced crosssection spaced from the free end of the pins and insulating sleeve members secured around the pins in said regions of reduced cross-section, each sleeve member being fixed in position by joining together abutting edges extending along the pins.

2. An electrical plug device according to claim 1 in which each sleeve member is formed in two or more parts, the parts being joined together when located in position around the regions of reduced cross-section.

3. An electrical plug device according to claim 1 in which each sleeve member is formed in one piece.

4. An electrical plug device according to claim 1 or claim 2 in which the pins have a rectangular cross-section and each sleeve member is made in two parts joined together along edges extending parallel to the length of the pins.

5. An electrical plug device according to claim 4 in which each pin of rectangular cross-section has a short side and a long side, the joins in each sleeve member being located on a short side of the rectangular pin.

6. An electrical plug device according to claim 4 in which each join in a sleeve member is located along a corner joining two sides of a rectangular pin.

7. An electrical plug device according to any one of the preceding claims in which the join between abutting edges is effected by welding.

8. An electrical plug device according to any one of the preceding claims in which the join between abutting edges is formed by ultrasonic techniques.

9. An electrical plug device according to any one of the preceding claims in which the join between abutting edges is formed by bonding using an adhesive.

10. An electrical plug device substantially as hereinbefore described with reference-to and shown in the accompanying drawings.