GB2263823A

GB2263823A - Electrical connector with shielding to prevent spark ignition of surrounding atmosphere.

Info

Publication number: GB2263823A
Application number: GB9201645A
Authority: GB
Inventors: William Morris Graham; Joseph William Hulse; Timothy James Spencer
Original assignee: Siemens Plessey Electronic Systems Ltd
Current assignee: BAE Systems Defence Systems Ltd
Priority date: 1992-01-25
Filing date: 1992-01-25
Publication date: 1993-08-04
Anticipated expiration: 2012-01-25
Also published as: GB2263823B; JPH05303986A; EP0553618A1; GB9201645D0; AU3191993A

Description

2263823 ELECTRICAL CONNECTOR This invention relates to electrical

connectors and more especially it relates to electrical. connectors which include integral shielding to contain electric arcs which may be produced when the connector is parted.

Such connectors are known, but known connectors either suffer from the disadvantage, for some applications, that they do not lend themselves to parting with a straight pull, or the disadvantage that arc containment is not sufficiently good for the connector to be suitable for use in the presence of explosive or inflammable gases.

One important object of the present invention therefore is to provide a connector in which the aforementioned disadvantages are obviated.

According to the present invention an electrical cable connector comprises mutually engagable plugs and sockets having terminals for connection to conductors of cables to be mutually connected and two shields disposed one within the other which enshroud the plugs and sockets whilst they are mutually 'engaged thereby to shield them from the surrounding atmosphere and which shields are withdrawn automatically when the connector is parted consequent upon predetermined disengagement of the plugs and sockets whereby any arc thereby produced becomes extinguished whilst shielded and before the plugs and sockets are exposed to the surrounding atmosphere.

The two shields may comprise a first shield disposed co-axially within a second shield.

The first shield may be spaced apart from the plugs and sockets and may be fabricated of conductive material so as electrically to screen them.

The first shield may be adapted and arranged to part and become withdrawn before the second shield when the connector is pulled apart whereby any arc produced as the conductive first shield is parted is contained.

The first shield may comprise a pair of conductive sleeves associated with respective parts of the connector, the sleeves being arranged to fit contiguously one within the other.

The first shield may comprise a tubular male sleeve part which plugs into an annular female sleeve part.

The male and female parts of the said first shield may each be adapted for connection to a screen of the cables to be mutually connected.

The second shield may comprise a flexible bellows, tubular end portions of which are respectively arranged contiguously to embrace respective parts of the connector.

Alternatively the second shield may comprise a tubular sleeve which is arranged to enshroud one connector part and which is secured thereto, into which tubular sleeve the other connector part is arranged contiguously to fit in a gas tight manner.

The second shield may be fabricated of insulating material.

Some embodiments of the invention will now be described by way of example only with reference to the accompanying drawing in which; 1 Figure 1 is a somewhat schematic sectional view of a cable connector showing two alternative outer shield arrangements and in which; Figure 2 is an end view of a part of the connector shown in Figure 1.

Referring now to Figure 1, a cable connector comprises two main parts 1 and 2. The part 1 comprises plug pins 3 and the part 2 comprises connector sockets 4. As shown in Figure 2, which is an end view of a portion of the connector part 1, three plug pins 3 are provided and accordingly three complementary socket connectors 4 (not all shown) are provided in the connector part 2.

The plug pins 3 are enshrouded by an annular sleeve 5 into which a tubular sleeve 6, which enshrouds the connector socket 4, is arranged to fit. The pins 3 are supported in a block of insulating material 7 each pin being arranged to receive a conductor 8. Similarly the connector sockets 4 are supported in a block of insulating material 9 and each connector socket 4 is arranged to receive a conductor 10 secured in a cable clamp 11. The annular sleeve 5 and the tubular sleeve 6 are arranged to fit tightly to the insulator blocks 7 and 9 respectively and to be secured to annular end portions 12 and 13 respectively, only part of which is shown in Figure 1.

The sleeves 5 and 6, which together define a first shield, are arranged to be enshrouded by a second shield. The second shield may simply comprise a tubular sleeve 14 (a part only of which is shown in the drawing) arranged to fit tightly at one end to the tubular sleeve 6 and at the other end to fit over the annular sleeve 5.

The tubular sleeve 14 is arranged to embrace the annular sleeve 5 with a gas tight fit and this is facilitated by means of an annular sealing ring 15.

As an alternative to the simple tubular sleeve 14, a tubular bellows 16 may be provided fabricated of flexible insulating material and arranged to fit tightly at one end around the annular sleeve 5 and at the other end around the tubular sleeve 6.

When the main parts 1 and 2 of the connector are pulled apart it is arranged that the connector pins 3 and connector sockets 4 disengage and part firstly. The tubular sleeve 6 is then withdrawn from the annular sleeve 5 but contact between these two parts is not broken until the space between the pins 3 and connector sockets 4 is at least 20 millimetres i.e. a distance sufficient such that any arc produced becomes extinguished. As the two parts 1 and 2 are pulled further apart, the second screen, as defined by the bellows 16 or the sleeve 14, is pulled apart but not until the sleeves 5 and 6 have become well spaced apart whereby any risk of an arc between these parts is obviated. If a bellows such as the bellows 16 is used as the second screen, one end of the bellows may simply be arranged to be pulled from one of the connector parts 1 or 2. Alternatively the bellows may be made of material which will rupture when the parts of the connector are pulled apart with sufficient force.

Various modifications may be made to the arrangement shown without departing from the scope of the invention, and for example an electrical connector having any number of plugs and socket connectors may be used with or without an outer screen conductor. It will be also be appreciated that alternative double shield configurations are possible wherein shielding provided by two shields is maintained until after the electrical connectors have parted and the risk of arc exposure to the surrounding atmosphere is no longer present.

Claims

1. An electrical cable connector comprising mutually engagable plugs and sockets having terminals for connection to conductors of cables to be mutually connected and two shields disposed one within the other which enshroud the plugs and sockets whilst they are mutually engaged thereby to shield them from the surrounding atmosphere -and which shields are withdrawn automatically when the connector is parted consequent upon predetermined disengagement of the plugs and sockets whereby any arc thereby produced becomes extinguished whilst shielded and before the plugs and sockets are exposed to the slirrounding atmosphere.

2. A connector as claimed in claim 1, wherein the two shields comprise a first shield disposed co-axially within a second shield.

3. A connector as claimed in claim 2, wherein the first shield is spaced apart from the plugs and sockets and is fabricated of conductive material so as electrically to screen them.

4. A connector as claimed in claim 3, wherein the first shield is adapted and arranged to part and become withdrawn before the second shield when the connector is pulled apart whereby any arc produced as the conductive first shield is parted is contained.

5. A connector as claimed in claim 4, wherein the first shield comprises a pair of conductive sleeves associated with respective parts of the connector, the sleeves being arranged to fit contiguously one with the other.

6. A connector as claimed in claim 5, wherein the first shield comprises a tubular male sleeve part which plugs into an annular female sleeve part.

7. A connector as claimed in claim 5, wherein the male and fernal parts of the said first shield are each adapted for connection to a screen of the cables to be mutually connected.

8. A connector as claimed in any preceding claim, wherein the second shield comprises a flexible bellows, tubular end portions of which are respectively arranged contiguously to embrace respective parts of the connector.

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9. A connector as claimed in any of claims 1 to 7, wherein the second shield comprises a tubular sleeve which is arranged to enshroud one connector part and which is secured thereto, into which tubular sleeve the other connector part is arranged contiguously to fit in a gas tight manner.

10. A connector as claimed in claim 8 or claim 9, wherein the second shield is fabricated of insulating material.

11. A connector substantially as hereinbefore described with reference to the accompanying drawings.