GB2233509A

GB2233509A - Shuttered electrical socket

Info

Publication number: GB2233509A
Application number: GB8911309A
Authority: GB
Inventors: Yung-Chia Chen; Yung-Chung Chen; Wah Yuk Li
Original assignee: TAIWAN NPC Ltd
Current assignee: TAIWAN NPC Ltd
Priority date: 1989-05-17
Filing date: 1989-05-17
Publication date: 1991-01-09
Anticipated expiration: 2009-05-17
Also published as: GB2233509B; GB8911309D0

Abstract

At present the possibility of an electric shock arises through the easy access of the electrical contacts in an electrical socket. Thus, an electrical socket having two electrical contacts 2, a housing base 4, a shutter base 6, two interlocking shutters 8 and a housing top 10 is disclosed. The shutters 8 interlock (see figure 2) such that simultaneous insertion of a pair of pins of an electrical plug is required to enable the shutters 8 to slide aligning holes 36 to reveal the respective electrical contacts 2. Insertion of a single pin slides one shutter (8) via a chamfer (34) to reveal and engage the pin with only a blind groove (38) in the other shutter and to thus block sliding of the other shutter by a later inserted second pin. The shutters are spring-returned by arms (40). The electrical socket also includes a pair of resilient ribs 20 disposed adjacent each electrical contact 2 for improving the contact force and to reduce metal fatigue. <IMAGE>

Description

Electrical Socket The present invention relates to an electrical socket and particularly to an electrical socket having safety features.

At present. electricity is supplied to industrial, commercial or domestic buildings by way of electrical sockets. An electrical socket has at least two electrical contacts disposed therein and provides access via a hole in the socket for each respective contact.

When the electrical socket is not in use, the electrical contacts may be easily accessed. If, a person inserts an electrical conductor into one of the holes and makes contact with one of the electrical contacts, then the person may receive an electrical shock.

Another main disadvantage with current electrical sockets is due to the deterioration and metal fatigue of the electrical contacts. If, an electrical socket is subjected to a plug being inserted and extracted many times, then the deterioration on the electrical contacts increases. This may result in poor electrical contact, increased consumption of electricity and the possibility of a short circuit leading to electrical shock.

An aim of the present invention is to provide an electrical socket having safety features.

According to the present invention there is provided an electrical socket having two or more electrical contacts disposed therein, a housing having at least two holes for providing access to a respective electrical contact and means for masking a hole whereby at least two means inter lock for enabling the respective electrical contacts only to be accessed simultaneously.

Also according to the present invention there is provided an electrical socket having two or more electrical contacts disposed therein. a housing having at least two holes, each hole for providing access to a respective electrical contact. and means for masking a hole whereby at least two means interlock for enabling the respective electrical contacts only to be accessed simultaneously and in which each electrical contact comprises a first portion extending in a direction parallel to the direction of insertion and extraction of a pin of a plug and the electrical socket further comprises a pair of resilient ribs disposed adjacent to each said first portion for improving the contact force of each first portion with a respective pin.

Thus, the present invention provides an electrical socket which reduces the possibility of an electric socket.

An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, of which: Fig 1 is an exploded diagram of an electrical socket according to a preferred embodiment; Fig 2 is a perspective view of two interlocking shutters according to the preferred embodiment; and Fig 3 is a partial view of the housing base of an electrical socket.

The preferred embodiment of the present invention comprises two electrical contacts 2, a housing base 4, a shutter base 6, two interlocking shutters 8, and a housing top 10. Preferably, the electrical contacts 2 are fabricated from a conductive material such as brass and the remaining parts of the electrical socket are fabricated from a resilient material or plastic. The electrical contacts 2 incorporate punch and tap threads for enabling a metallic screw 12 to couple the socket to the electricity source via a wire (not shown) and to fix the wire. The current carrying wires are disposed in a U-shaped channel 14 provided in the housing base 4.

Thus, the wires and screws may be secured and channelled so as to avoid any contact with a wire connection box (not shown).

The electrical contacts 2 are each provided with four protrusions 16 which are disposed at each corner of the electrical contact 2. After, the electrical contact 2 has been inserted sideways into the housing base 4, each protrusion 16 rests in a respective groove 18, as shown in figure 3. The protrusions coupled with a respective groove 18 enables the electrical socket to withstand a greater number of insertions and extractions of a plug then known hitherto.

The housing base 4, is also provided with a pair of ribs 20 for each electrical contact 2. The ribs 20 are disposed contiguous with a respective electrical contact 2 and not only facilitate the electrical contact 2 to regain its' original position but also improves the contact force of the electrical contact 2 with a respective pin of an electrical plug. Thus, the problems of metal fatigue, increased consumption of electricity and the possibility of short circuit developing are reduced by introducing this safety feature.

The housing base 4 is also provided with a number of supporting ribs 22. There are four triangular ribs disposed at each corner and two rectangular ribs disposed on opposite walls of the base 4. These ribs 4 provide support for the shutter base 6 so that the shutter base will not contact the electrical contacts 2, thereby ensuring that the electrical contacts 2 function efficiently.

The shutter base 6 is provided with a hole 24 for each electrical contact 2. These holes 24 are always situated directly above the electrical contacts 2 and enable the pins of a electrical plug to pass therethrough. The shutter base 6 is also provided with four pillars for each electrical contact, so that when the shutter base 6 is disposed within the housing base 4, each of the pillars 26 rests on a respective protrusion 16 of the electrical contact 2. This enables the electrical contacts 2 to maintain an upright position and to not move up and down on the insertion and extraction of a respective pin of an electrical plug. The shutter base 6 is furthermore provided with a pair of guiding ribs 28 for enabling the shutters 8 to be correctly positioned, especially when the shutters 8 are sliding to and fro.

Each shutter 8 corresponds to a respective electrical contact 2 and preferably a shutter is provided for the live and neutral electrical contacts. The two shutters 8 interlock so as to only allow access to the electrical contacts simultaneously thereby creating a second safety feature.

Each shutter 8 comprises a front end 30 and a rear end 32. When the shutters 8 interlock, as shown in figure 2, the front end 30 of each shutter 8 overlies the rear end 32 of the other shutter. Thus two layers of shutters are presented to each pin. For each shutter 8.

the front end 30 comprises an inclined portion 34 whilst the rear end 32 comprises a rectangular hole 36, a groove 38 and resilient means 40. In this embodiment, the resilient means 40 comprises a "v" shaped rib which is formed by injection moulding to become an integral part of the shutter 8. The inclined portion 34 receives pressure from the pin of a respective plug and slides the shutter in a direction perpendicular to the direction of the pressure from the pin. The resilient means 40 enables the shutter to slide back to return to it's original position when the pressure from the pin has been removed.

The interlocking shutters 8 are disposed within the guiding ribs 28 on the shutter base 6. The housing top 10 couples with the housing base 4 to complete the electrical socket. A hook 42 is disposed on each side of the housing top 10 to couple with a slot 44 provided in the housing base 4. Naturally, the housing top 10 is provided with a hole 46 for providing access to a respective electrical contact via the shutters 8. The socket top 10 is also provided with a pair of flanges 48 for enabling the electrical socket to be assembled to an outer cover or case (not shown).

When the electrical socket has been assembled and is not in use, a housing top hole 46, an inclined portion 34, a groove 38, a hole 24 of the shutter base 6, and a respective electrical contact 2 are all directly aligned. When a pair of pins of an electrical plug are inserted simultaneously, the pressure exerted on the inclined faces 34, forces each of the shutters 8 to slide until their respective holes 36 lie directly above the holes 24 of the shutter base 6 and the electrical contacts 2. The pins can then proceed to contact the electrical contacts 2.

If, however, a single pin is inserted into one of the holes 46 of the socket 10, it will first contact the inclined portion 34 of one of the shutters 8A. The pressure on the inclined portion 34 will force the shutter BA to slide but since the inclined portion 34 of the other shutter 8B receives no force or pressure, then this shutter 8B remains stationary and thus only reveals its groove 38. The groove 38 of this other shutter 8B blocks the entry of the pin to the electrical contact, thereby obviating the risk of an electrical shock. If another pin is inserted into the other hole 46 of the socket top 10 the pin will contact the inclined face 34 of this shutter 8B but will be unable to move the shutter by applying pressure to the inclined face 34.

This is because the first pin has contacted the groove 38 of the shutter 8B and prevents this shutter from moving. Consequently, either a single pin or two pins presented successively cannot penetrate the shutters to contact the electrical contacts. Thus, two pins are needed to be inserted simultaneously into the electrical socket. Thus. the preferred embodiment enables the risk of an electrical shock to be greatly reduced.

The fore going description has been given by way of example only and it will be appreciated by a person skilled in the art that modifications may be made without departing from the scope of the present invention. For example, the preferred embodiment of the present invention only includes a two pin electrical socket. However, the present invention is equally applicable to a three pin electrical socket whereby the shutters 8 are disposed above the live and neutral contacts and the earth contact is permanently accessible or is masked by a shutter interlocking with the other two shutters.

Claims

1. An electrical socket having two or more electrical contacts disposed therein, a housing having at least two holes, each hole for providing access to a respective electrical contact1 and means for masking a hole whereby at least two means interlock for enabling the respective electrical contacts only to be accessed simultaneously.

2. An electrical socket as claimed in claim 1, in which said means comprises a planar member at one end and an inclined member at the other end, such that the inclined member overlies the planar member when said two means interlock.

3. An electrical socket as claimed in claim 2, in which the planar member includes a hole for enabling the pin of an electrical plug to pass therethrough.

4. An electrical socket as claimed in claim 2 or claim 3, in which the planar member includes a groove.

5. An electrical socket as claimed in claim 4. in which the groove is arranged parallel to the hole and the hole is disposed between the groove and the inclined member.

6. An electrical socket as claimed in any one of claims 2 to 5, in which said means includes a resilient means at one end.

7. An electrical socket as claimed in any one of claims 1 to 6, in which the electrical contacts comprise a first portion extending in a direction parallel to the direction of insertion and extraction of a pin of a plug and a plurality of further portions extending in a plane perpendicular to the direction.

8. An electrical socket as claimed in claim 7, further comprising means for applying a retaining force in said direction on the further portions.

9. An electrical socket as claimed in claim 1, in which each electrical contact comprises a first portion extending in a direction parallel to the direction of insertion and extraction of a pin of a plug and further comprises a pair of resilient ribs disposed adjacent to each said first portion for improving the contact force of each first portion with a respective pin.

10. An electrical socket substantially as herein before described with reference to any one of the accompanying drawings.