GB2344467A

GB2344467A - Preventing sparking of electrical connectors

Info

Publication number: GB2344467A
Application number: GB9821344A
Authority: GB
Inventors: Norman Reed
Original assignee: TEC Electrical Components Ltd
Current assignee: TEC Electrical Components Ltd
Priority date: 1998-10-02
Filing date: 1998-10-02
Publication date: 2000-06-07
Also published as: GB9821344D0

Abstract

Pins 20 are brought into electrical contact with sockets 18 by a thread 54 of a connector housing 26 rotating on a thread 56 on a socket housing. A rearwardly and outwardly diverging surface 60 on the socket housing is first aligned with the O ring 42 and then engages with an O ring 44 to seal therewith and compress that ring. Subsequent to the O rings being so engaged, further axial advancement causes the pins to make electrical contact with the sockets. The region that the pins and sockets have in common is sealed from the ambient surroundings by the interiors of the pin housing 24 and the socket housing 52 and by the O ring seals 38 and 44 and also by the interior of the ring housing 32. The resilience of the O ring seal will enable any explosion in that region to be contained with the resilience of the O ring seals assisting in absorbing the initial expansion on ignition.

Description

PARKING OF ELECTRICAL CONNECTORS The present invention relates to an electrical connector and also to a method of operating an electrical connector.

In known connectors that are used where there is a risk that explosive gases may be present, extreme care has to be taken when connecting or disconnecting the terminals. If there is a risk that the terminals may be live when they contact each other and if explosive gas is present then ignition can occur. Thus the connector can fail and other parts may also be damaged by the explosion or fire. Clearly this is-not desirable, particularly where the connectors are being used in missile systems in aircraft.

One prior method of ensuring that the connector is not live when the terminals are connected and disconnected has been to instal a relay. This relay is linked to the connector and it automatically ensures that the current is turned off when terminals are moving into or out of contact with each other. The provision of the additional relay is bulky. As space and weight are at a premium in aircraft then, quite apart from the expense of such a relay and the possibility that the relay could fail, such relays have significant disadvantages.

Another method used to try and tackle this problem has been to incorporate a detection system for any current that may be flowing just prior to disconnection. A dowsing system is then used to minimise or prevent any spark that may otherwise be created on disconnection.

This system is again bulky, unreliable and is not cost effective. In such critical applications it is also deemed essential that the above systems are backed up or duplicated by a mechanical system ensuring safe connection and disconnection.

According to one aspect of the present invention an electrical connector comprises first and second connector portions including first and second electrical contacts respectively, the connector portions being movable relative to each other to make and to break electrical connection between the first and second electrical contacts, the first and second connector portions being arranged to define a sealed region between them when electrical connection is made between the first and second electrical contacts characterised in that the first and second connector portions are arranged to effect the sealed region between them prior to electrical connection being made between the first and second electrical contacts.

The sealed region may be arranged to be maintained between the first and second portions after electrical connection between the first and second electrical contacts has been broken.

The sealed region may comprise a space. That space may remain even after the first and second connector portions are fully connected. The space may be arranged to be reduced when the first and second portions are moved towards each other.

The seal may be arranged to be maintained after initial contact of the first and second electrical contacts whilst the first and second electrical contacts continue relative movement in the direction of the connector portions that brought them into their initial contact.

The first and second connector portions may include at least one pair of cooperating key and keyways arranged to control the relative angular orientation of the connector portions during their relative movement.

The key and keyways may be arranged to cause linear movement of the first and second electrical contacts during relative movement.

The key and key way may be arranged to cooperate to control the relative angular orientation prior to said sealed region being defined when said first and second portions are moved in a relative direction towards each other.

The connector may include mechanical connection means arranged to resist relative movement of the connector portions away from each other or towards each other or both.

The mechanical connection means may be arranged to be engaged before the sealed region is defined upon relative movement of the connector portions to make the electrical connection. The mechanical connection means may be arranged to continue to be engaged as relative movement of the first and second connector portions occurs to bring the first and second electrical contacts into electrical connection with each other.

The mechanical connection means may be arranged to cause movement of the first and second connector portions towards each other or away from each other or both.

The mechanical connection means may comprise cooperating thread portions respectively mounted on the first and second connector portions whereby relative rotation of the threaded portions is arranged to cause relative translational movement of the electrical contacts.

The mechanical connection means may be arranged to be connected to each other after the key and key way have been engaged.

The seal may comprise a resilient seal. The seal may be arranged to be engaged when relative linear movement of the first and second connector portions occurs towards each other. The seal may be arranged to be compressed when the first and second connector portions are moved towards each other. The seal may be located in a groove of one of the first and second connector portions such that when the other of the connector portions engages and seals therewith the area defined by the groove and the surface of the other connector portion that engages with the seal is greater than the area defined by the compressed seal.

A seal may be arranged to be replaced after electrical contact has been made and whilst electrical contact continues to be made between the first and second electrical contacts. The seal may be arranged to be replaced by causing axial movement of the seal relative to the first and second electrical contacts. Releasable locking means may be arranged to control whether relative axial movement of the seal and the first and second electrical contacts is able to occur.

A seal may be mounted in a groove on a seal housing.

The seal housing may include two axially spaced seals, one of which is arranged to seal between both the first and second connector portions and the other one of which is arranged to seal with parts of one of the first and second portions that are arranged to rotate relative to each other.

The connector portions may include an abutment seal that is arranged to be engaged substantially when the first and second electrical contacts are fully mated with each other.

The first electrical contacts may comprise pins. The second electrical contacts may comprise sockets.

The present invention also includes a method of operating an electrical connector comprising moving first and second connector portions towards each other whereby first and second electrical contacts on each portion are brought into electrical contact with each other, the method comprising causing the first and second connector portions to seal with each other prior to electrical contact being made.

The method may comprise causing the seal to be maintained after the electrical contact has been broken.

The method may comprise maintaining the seal after initial connection of the first and second electrical contacts and during subsequent movement of the contacts towards each other.

The method may comprise maintaining a space defined between sealed portions of the connector when the electrical contacts are fully engaged with each other.

The method may comprise guiding the relative movement of the connector portions towards and away from each other. The method may comprise guiding that movement in a linear direction. The method may comprise guiding the movement of the first and second portions before the seal between the connector portions is effected.

The method may comprise mechanically connecting the first and second connector portions and the method may comprise so mechanically connecting the portions prior to the seal between the portions being effected. The method may comprise maintaining the mechanical connection whilst the connector portions are being moved towards each other, or away from each other, or both, to make or break the electrical connection and the method may comprise maintaining the mechanical connection when the connection between the first and second electrical contacts has been made.

Relative movement of the mechanical connection means between the first and second connector portions may be arranged to cause the movement of the connector portions towards each other, or away from each other, or both.

The mechanical connection means may be connected between the first and second connector portions after the means to effect linear movement between the first and second connector portions has been imposed.

The method may comprise effecting the seal between the first and second connector portions by causing relative translational movement between those portions.

The method may comprise compressing a seal when effecting the seal between the first and second connector portions. The method may comprise permitting the seal to expand to increase the size of the sealed region should there be a sudden increase in volume in the sealed region.

The method may comprise the seal moving to increase the area defined by the sealed region should there be a sudden increase in volume in the sealed region.

The method may comprise replacing a seal after electrical contact has been made, whilst maintaining electrical contact.

The present invention includes any combination of the herein referred to features or limitations.

The present invention can be carried into practice in various ways but one embodiment will now be described, by way of example, and with reference to the accompanying drawings in which: Figure 1 is a side sectional view through a receptacle 10 of a connector; Figure 2 is an end view on arrow B of Figure 1; Figure 3 is a side cross-sectional view of a plug 12 of a connector; Figure 4 is an end view of Figure 3 taken on arrow A, and Figure 5 is a side sectional view of the plug and receptacle in their connected position.

The receptacle 10 is arranged to be secured to a part of an aircraft with bolts, for instance, that pass through holes 14 in an end plate 16, as seen in Figure 2.

All parts of the receptacle are fixed in both a rotational and a translational sense. The forward end of the receptacle provides six sockets 18 into which pins 20 from the plug enter in order to make electrical contact.

The plug incorporates an inner hollow housing 22 to the inside of which a mounting 24 for the pins 20 is secured. The housing 22, pins 20 and mounting 24 are constrained to move together.

The outside of the housing 22 has a cylindrical connection assembly 26 attached thereto. A spirolox retention ring 28 is located in an inwardly facing groove of the assembly 26 to hold a back up ring 30 in place.

That ring 30 abuts an axially facing flange on the outer surface of the housing 22 to restrict translational movement in the relative direction. The back up ring can be replaced without breaking the electrical connection.

Furthermore, with the back up ring removed, the connector housing 26 can be slid axially, along and with and then away from the O ring housing 32 to allow both O rings to be changed without breaking the electrical contacts.

An'O'ring housing 32 is located on the inner surface of the housing 22 and is constrained to move axially with the housing 26 by bearing against a flange 36 at one end and with the ring 30 at the other end. The housing 32 includes two spaced inwardly extending annular grooves 38 and 40 in which are located flexible resilient 0 rings 42 and 44. In the relaxed position shown in Figure 3, the ring 44 projects further inwards than the inner walls of the grooves 40.

The O ring 42 seals the space between the 0 ring housing 32 and the pin housing 22.

An inwardly extending annular flange 46 of the housing abuts with an axially extending face of the housing 22 to restrict axial movement in one direction.

The connecting assembly 26 is thus able to move rotationally with respect to-the O ring housing 32 and the pin housing 22. All parts though are constrained to move translationally together.

The connection of the plug to the receptacle will now be described.

The plug is advanced axially until axially extending flanges or keys 48 extend outwardly from the forward end of the plug housing 22 are located in corresponding axially extending slots or keyways 50 of the receptacle.

The keyways 50 are formed on the inner cylindrical surface of a socket housing 52. Once the keys 48 and located in the keyways 52, the pins 20 are correctly axially aligned with the sockets 18.

After the keys are located further axial advancement of the plug brings an inwardly facing thread 54 at the front of the connector housing 26 into cooperation with the thread 56 located on the outer surface of the socket housing. Rotation of the connector housing by gripping and turning a knurled portion 58 thereof causes further axial advancement of the plug.

During advancement upon cooperation of the threads 54 and 56 a rearwardly and outwardly diverging surface 60 at the socket housing is first aligned with the O ring housing by being guided by a forwardly and outwardly diverging surface 61 of that housing and then engages the 0 ring 44 to seal therewith and compress that ring before the ring 44 comes into sealing engagement with the outer cylindrical surface 62 of the socket housing 52.

Still further axial advancement causes the pins to contact and be pushed into-the sockets in the position shown in Figure 5. In this position a seal 64 located in the socket housing 52 is abutted by the forward end of pin housing 22 to seal those parts at that location.

An operator is aware that the contacts are fully engaged when an orange mark 65 on the socket housing is concealed by the connector housing 26.

Disconnection is a reversal of the above described sequence.

Each pin and socket connection may carry milli-amps in part of a missile control system. It is important to ensure that any spark that may occur on the making or breaking of electrical contact is not able to ignite or explode the ambient gases that surround the connector.

Although the connector will normally be non-live during such making or breaking of the pins and sockets, nevertheless it is possible that the pins and sockets could in error, be live, and it is for this eventuality that the present invention is provided.

Accordingly, assuming that the pin and socket connections are being made whilst the ambient gases are combustible, and assuming that power is supplied to the contacts such that sparking is likely to occur, consideration will now be given to the effect of such a spark.

Just prior to electrical contact the plug and receptacle are axially aligned by the cooperating keys 48 and keyways 50. The plug and receptacle are also constrained together in the axial direction by the cooperating threads 54 and 56. Furthermore, the region that the pins and sockets have in common is sealed from the ambient surroundings by,-first of all, the interiors of the pin housing 22 and the socket housing 52, and then by the O ring seals 38 and 44 and also by the interior of the ring housing 32.

Thus, should a spark occur and should the gas within the sealed space of the connector ignite or explode, that reaction will be contained within the sealed space and will not set off any reaction outside of that space.

Furthermore, the resilience of the O ring seals assists in absorbing the initial expansion on ignition by being compressed by the force of the ignition. In addition, it can be seen that the annular grooves 38 and 40 that accommodate the O rings are larger in axial dimension than those rings, even after the rings are in a sealing condition. Accordingly the 0 rings may be pushed in an axial direction by the ignition force or compressed in that direction by that force or a combination of both pushing and compression.

Similarly any ignition will be contained within the connector should there be ignition on separation of the electrical contacts.

It will be seen that the space that is sealed when the pins are fully in the sockets is also sealed prior to the electrical contact being made. Accordingly, on drawing the parts together, there will be compression of that space. That compression is able to be absorbed because of the relatively significant volume of compressible air or gas within the connector. That space is defined, in the closed position, between the majority of the extent of the socket housing 52 where the keyways are located and the inner-spaced portion of the pin housing 22 that surrounds the projecting pins. The space is also defined between the inner portion if the seal housing 32 and the other coextensive portion of the keyway portion of the socket housing.

It will be appreciated that the pins and sockets could be located in either of the housings and that the housing 22 could be the one that is fixed in position with the other housing 52 being the one that is advanced and retracted to make or break the connections.

The rader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment (s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

CLAIMS 1. An electrical connector comprising first and second connector portions including first and second electrical contacts respectively, the connector portions being movable relative to each other to make and to break electrical connection between the first and second electrical contacts, the first and second connector portions being arranged to define a sealed region between them when electrical connection is made between the first and second electrical contacts characterised in that the first and second connector portions are arranged to effect the sealed region between them prior to electrical connection being made between the first and second electrical contacts.
2. A connector as claimed in Claim 1 in which the sealed region is arranged to be maintained between the first and second portions after electrical connection between the first and second electrical contacts has been broken.
3. A connector as claimed in Claim 1 or 2 in which the sealed region comprises a space.
4. A connector as claimed in Claim 3 in which the space remains even after the first and second connector portions are fully connected.
5. A connector as claimed in Claim 3 or 4 in which the space is arranged to be reduced when the first and second portions are moved towards each other.
6. A connector as claimed in any preceding claim in which the seal is arranged to be maintained after the initial contact of the first and second electrical contacts whilst the first and second electrical contacts continue relative movement in the direction of the connector portions that brought them into their initial contact.
7. A connector as claimed in any preceding claim in which the first and second connector portions include at least one pair of cooperating key and keyways arranged to control the relative angular orientation of the connector portions during the relative movement.
8. A connector as claimed in Claim 7 in which the key and keyways are arranged to cause linear movement of the first and second electrical contacts during relative movement.
9. A connector as claimed in Claim 7 or 8 in which the key and keyways are arranged to cooperate to control the relative angular orientation prior to said sealed region being defined when said first and second portions are moved in a relative direction towards each other.
10. A connector as claimed in any preceding claim including mechanical connection means arranged to resist relative movement of the connector portions away from each other.
11. A connector as claimed in any preceding claim including mechanical connection means arranged to resist relative movement of the connector portions towards each other.
12. A connector as claimed in Claim 10 or 11 in which mechanical connection means are arranged to be engaged before the sealed region is defined upon relative movement of the connector portions to make electrical connection.
13. A connector as claimed in Claim 12 in which the mechanical connection means are arranged to continue to be engaged as relative movement of the first and second connector portions occurs to bring the first and second electrical contacts into electrical connection with each other.
14. A connector as claimed in any of Claims 10 to 13 in which the mechanical connection means are arranged to cause movement of the first and second connector portions towards each other.
15. A connector as claimed in any of Claims 10 to 14 in which the mechanical connection means are arranged to cause movement of the first and second connector portions away from each other.
16. A connector as claimed in any of Claims 10 to 15 comprising cooperating thread portions respectively mounted on the first and second connector portions whereby relative rotation of the threaded portions is arranged to cause relative translational movement of the electrical contact.
17. A connector as claimed in any of Claims 10 to 16 when dependent upon any of Claims 7 to 9 in which the mechanical connection means are arranged to be connected to each other after the key and keyways have been engaged.
18. A connector as claimed in any preceding claim in which the seal comprises a resilient seal.
19. A connector as claimed in Claim 18 in which the seal is arranged to be engaged when relative linear movement of the first and second connector portions occurs towards each other.
20. A connector as claimed in Claim 18 or 19 in which the seal is arranged to be compressed when the first and second connector portions are moved towards each other.
21. A connector as claimed in any of Claims 18 to 20 in which the seal is located in a groove of one of the first and second connector portions such that when the other of the connector portions engages and seals therewith the area defined by the groove and the surface of the other connector portion that engages with the seal is greater than the area defined by the compressed seal.
22. A connector as claimed in any of Claims 18 to 21 in which the seal is arranged to be replaced after electrical contact has been made and whilst electrical contact continues to be made between the first and second electrical contacts.
23. A connector as claimed in Claim 22 in which the seal is arranged to be replaced by causing axial movement of the seal relative to the first and second electrical contacts.
24. A connector as claimed in Claim 22 or 23 in which releasable locking means are arranged to control where the relative axial movement of the seal and the first and second electrical contacts is able to occur.
25. A connector as claimed in any preceding claim including a seal mounted in a groove on a seal housing.
26. A connector as claimed in Claim 25 in which the sealed housing includes two axially spaced seals, one of which is arranged to seal between both the first and second connector portions and the other one of which is arranged to seal with parts of one of the first and second portions that are arranged to rotate relative to each other.
27. An arrangement as claimed in any preceding claim in which the connector portions include an abutment seal that is arranged to be engaged substantially when the first and second electrical contacts are fully mated with each other.
28. An arrangement as claimed in any preceding claim in which the electrical contacts comprise pins.
29. An arrangement as claimed in any preceding claim in which the second electrical contacts comprise sockets.
30. An electrical connector substantially as herein described with reference to, and as shown in any of Figures 1 to 5.
31. A method of operating an electrical connector comprising moving first and second connector portions towards each other whereby first and second electrical contacts on each portion are brought into electrical contact with each other, the method comprising causing the first and second connector portions to seal with each other prior to electrical contact being made.
32. A method as claimed in Claim 30 comprising causing the seal to be maintained after the electrical contact has been broken.
33. A method as claimed in Claim 31 or 32 comprising maintaining the seal after initial connection of the first and second electrical contacts and during subsequent movement of the contacts towards each other.
34. A method as claimed in any of Claims 31 to 33 comprising maintaining a space defined between the sealed portions of the connector when the electrical contacts are fully engaged with each other.
35. A method as claimed in any of Claims 31 to 34 comprising guiding the relative movement of the connector portions towards and away from each other.
36. A method as claimed in Claim 35 comprising guiding that movement in a linear direction.
37. A method as claimed in Claim 35 or 36 comprising guiding the movement of the first and second portions before the seal between the connector portions is effected.
38. A method as claimed in any of Claims 31 to 37 comprising mechanically connecting the first and second connector portions.
39. A method as claimed in Claim 38 comprising mechanically connecting the first and second portions prior to the seal between the portions being effected.
40. A method as claimed in Claim 38 or 39 comprising maintaining the mechanical connection whilst the connector portions are being moved towards each other.
41. A method as claimed in any of Claims 38 to 40 comprising maintaining the mechanical connection whilst the connector portions are being moved away from each other.
42. A method as claimed in any of Claims 38 to 41 comprising maintaining the mechanical connection when the connection between the first and second electrical contacts has been made.
43. A method as claimed in any of Claims 38 to 42 comprising relative movement of the mechanical connection means between the first and second connection portions causing the movement of the connector portions towards each other.
44. A method as claimed in any of Claims 38 to 43 comprising the relative movement of the mechanical connection means between the first and second connector portions causing the movement of the connector portions away from each other.
45. A method as claimed in any of Claims 38 to 44 comprising the mechanical connection means being connected between the first and second connector portions after the means to effect linear movement between the first and second connector portions has been imposed.
46. A method as claimed in any of Claims 31 to 45 comprising effecting the seal between the first and second connector portions by causing relative translational movement between those portions.
47. A method as claimed in any of Claims 31 to 46 comprising compressing a seal when effecting the seal between the first and second connector portions.
48. A method as claimed in Claim 47 comprising permitting the seal to expand to increase the size of the sealed region should there be a sudden increase in volume in the sealed region.
49. A method as claimed in Claim 48 comprising the seal moving to increase the area defined by the sealed region should there be a sudden increase in volume in the sealed region.
50. A method as claimed in any of Claims 31 to 49 comprising replacing a seal after electrical contact has been made whilst maintaining electrical contact.
51. A method of operating an electrical connector substantially as herein described with reference to, and as shown in any of the accompanying drawings.