GB2209887A - Electrical connectors - Google Patents

Abstract

An electrical connector comprises a plug (8) and corresponding socket (2). The plug comprises a pilot pin (31), having annular ring contacts which engage with resilient fingers in the socket (Fig. 3). The fingers are mounted on a movable face plate (24) which is urged into a contacting position by a spring (27). The movable face plate (24) is able to cater for variations in the length of the pilot pins (31) inserted in the socket. Alternatively a splined plug mates with a correspondingly splined socket (Figs. 4, 5), contacts being present between the splines. Both structures cater for tolerances in the length of plugs. <IMAGE>

Description

IMPROVEMENTS IN ELECTRICAL CONNECTORS This invention relates to electrical connectors.

The invention is particularly applicable to plug-andsocket electrical connectors for use in hazardous and/or corrosive environments.

A known pilot pin type plug and socket connector is illustrated in Figure 1 of the drawings. The known plug and socket connector designed for use in hazardous and/or corrosive atmospheres incorporates a single pilot pin. When the plug is withdrawn, this interrupts a protective circuit prior to power pins being withdrawn. A socket 1 is secured within an opening in an insulated moulding 2. Longitudinally extending slots are formed in the entrance to the socket 1. The arms 3 thus formed between the slots are urged radially inwardly by means of a circular spring clip 4. A first piece of cable 5 to be connected is received in the end of the socket part of the connector remote from the socket entrance and is secured by means of grub screws 6 received in threaded holes or other securing means.

The plug part of the connector comprises a pilot pin 7 which is secured within an opening of a further insulated moulding 8. The pin is received in the socket, being retained by the spring clip 4 bearing on the arms 3 and the entrance to the sockets. Again, a second piece of cable 3a, to be electrically connected to the first piece, is received in the opposite end of the plug assembly and similarly secured by grub screws or other securing means.

As mentioned, such plug and socket connectors are particularly suited for use in hazardous and/or corrosive environments. There is, however, an increasing demand for multicontact connectors which can interrupt a number of auxiliary protection circuits prior to breaking the main electrical contact when the plug and socket are disengaged. Design constraints imposed by virtue of the established use of conventional connectors as described above, make it preferable that any multi-contact connector can be fitted in an opening in an insulated mouldina or the like which was originally intended to accommodate conventional connector.

It is an object of the present invention to provide an electrical connector which occupies substantially the same space as equivalent known pilot pin type plug and socket connectors but which provides for the connection of a plurality of auxiliary circuits.

According to the present invention there is provided an electrical connector comprising a pin receivable in a corresponding socket, a plurality of first electrical contacts being located on the pin and a corresponding plurality of second electrical contacts being located in the socket, each first contact being in contact with a corresponding second contact when the pin is fully received in the socket. Each of the first electrical contacts will generally be mutually insulated from one another, and each of the second electrical contacts will generally be mutually insulated from one another.

A connector according to the present invention is designed to take up no more space than a conventional pilot pin type plug and socket connector and can thus replace an existing connector with a minimal amount of modification to the structure on which the connector is mounted. Preferably, the pilot pin is of the tip and ring type.

Preferably, the second contacts are mounted longitudinally within the socket on a transverse end plate. When so mounted it is preferable that the end plate is movable along the axis of the socket. In this case, the end plate can be urged by a spring to an initial working position in which the end plate abuts an annular ledge formed in the socket.

Alternatively, the socket can consist of an internally splined sleeve receivable into which is a pin the form of a complementarily externally splined shaft. In this form of the invention the first and second contacts are located on the surfaces of the radially outward channels and ridges of the socket and shaft respectively. Alternatively, conductors can be located on the radially inward ridges of the socket and the radially inward channels formed in the shaft. In one embodiment the splined sleeve and shaft are both formed from separate blocks of insulating material through which the contacts extend.

It is preferable that each plug and the socket is located securely within the body of a respective insulated moulding or the like through which the connection between the plug and socket is to be made.

The invention can be put into practice in various ways some of which will now be described by way of example with reference to the accompanying drawings in which: Figure 2 is a longitudinal section through a first embodiment of a connector according to the invention; Figure 3 is a longitudinal section through a second embodiment of a connector according to the invention; Figure 4 is a longitudinal section through a third embodiment of a connector according to the invention; Figure 5 is a cross section of a socket part of the connector in Figure 4; and Figure 6 is a cross section of a plug part of the connector in Figure 4.

Referring, firstly, to Figure 2 of the drawings, a first embodiment of a connector according to the invention is designed specifically to use the space in insulating mouldings or the like intended for conventional pilot pin type plug and socket connectors such as, for example, that shown in Figure 1.

A socket part 9 of the connector, located in an opening in an insulating moulding 2, comprises two main sprung contacts 10 and a pair of longitudinally extending auxiliary sprung contacts 11 of dissimilar length. The contacts 10 and 11 are electrically insulated from each other mounted in a face plate 12 of the socket 9. Cables 13 are received in an end of the opening remote from the socket entrance. The cables 13 are soldered, at terminals 14 to the contacts 10 and 11 which protrude through the face plate 12.

A metal sleeve 15 extends into the cable end of the opening and is secured to a threaded portion of the plate 12 extending away from the socket 9. A further metal sleeve 16 defines the aperture of the socket 9 into which a pilot pin 17 of a plug part of the connector is received.

To assemble the socket part of the connector each of the cables is soldered to a terminal 14. The sleeve is then passed over the cables and screwed onto the thread on the plate 12. The assembled socket is then inserted in the opening and held in place by a suitable fixing arrangement.

The pilot pin 17 of the plug part of the connector is mounted on a similar end plate 18 as that described above. However, the end plate 18 is assembled flush with the surface of its associated insulated moulding 8.

The pilot pin 12 is a tip-and-ring plug comprising a tip contact 19 and two ring contacts 20. Each contact 19 or 20 is electrically isolated from the other contact. Cables 21, extending into the opening, are each soldered to a respective terminal 22 thereby connecting it to a contact 10 or 11.

An annularly keyed sleeve 23 also extends into the insulating moulding surrounding the cable and is received on a threaded extension of the end plate 18.

The material of the insulated moulding 8 conforms to the outer shape of the keyed sleeve 23 and retains the plug part of the connector in place.

When the pilot end 17 is fully inserted in the socket 9, it is held in place by projections formed in the resilient metal contacts 10 which register with an annular detent in the pilot pin 17. The auxiliary contacts 11 slide along the length of the pilot pin 17 as it is inserted and makes electrical contact with a corresponding ring at full insertion. Clearly, the length of each auxiliary contact 11 is designed so that it registers with a specific ring on the pilot pin 17.

As it is necessary, in most cases, to break the pilot circuits associated with the auxiliary contacts 11 before the main circuit, usually associated with the tip of the pilot pin 17 and the main contacts 10, the number of rings and corresponding auxiliary contacts 11 is limited to three or possibly four by the predetermined length of the opening which was intended to accommodate the conventional connector.

It is possible to perform sequential disconnection of the auxiliary circuits such that a protective pilot circuit, associated with corresponding contacts 11 and 20 is disconnected both before the main supply control circuit and the remaining auxiliary pilot circuit during the withdrawal plug. In this way the protective pilot circuit removes the main supply from the main supply circuit before remaining axuiliary contacts are disconnected.

A second embodiment of the invention is illustrated in Figure 3. In this second embodiment, which is in many respects similar to the first embodiment, a spring positioning device is used to replace the rigid end face plate 12 in Figure 1.

A face plate 24 is a sliding fit in a sleeve 25 extending through the opening in the insulating moulding 2. However, the face plate 24 is urged to bear against an annular ledge 26 formed in the inner wall of the sleeve 25 under the influence of a spring 27. The spring 27 is braced against a packing washer 28 which is also a sliding fit in the sleeve 25. The washer 28 is retained in the sleeve 25 by means of an externally threaded collar 29 which engages a complementary thread in the internal wall of the sleeve 25 at the end thereof remote from the socket entrance.

The cables 13 pass through holes in the collar 29 and the washer 22 and are soldered to terminals mounted in the faceplate 24 as previously described.

The cavity which consists the socket into which the plug is received has an entrance defined by an insulated bush 30 secured to the internal wall of the sleeve 25 which has an internal diameter corresponding to the external diameter of a pilot pin 31 of a plug part of a connector.

The plug part of the connector comprises a metallic plastic plug body 32 located in an opening in the insulated moulding 8. A neck portion of the body 31 stands proud of the moulding 8. The pilot pin 31, comprising a tip contact and two ring contacts is screwed onto the neck. When the plug and socket are connected the tip and rings engage main and auxiliary contacts as before.

Turning now to Figures 4, 5 and 6, a third embodiment of the invention comprises a socket 33 constituted by an internally splined sleeve 15a. The sleeve is created in one end of a solid piece of insulating material 34. Strip-like conductors 35, which may be silver plated to reduce contact resistance, extend through the insulating material 34.

At the end of the material remote from the socket the conductors are soldered to cables 13. At the socket end of the material 34 the strip conductors are secured in the bottom of channels 36 defined by the radially inwardly projecting splines 37. It is preferable that the conductors are incorporated within the insulated material 34 during the moulding process.

The end of the insulating material 34 is removed or moulded at the end remote from the socket to expose the strip-like conductors 35 so that they may be soldered to the cables 13.

A complementary plug of the connector comprises an externally splined shaft 38 each of the radially outer edges of which are similarly covered with a strip of metallic conductor material 39.

Again, the splined shaft is formed from a single mark of insulating material 40 and the strip contacts 39 extend through the material onto the wall of a similar recess as above where they are soldered to cables 21.

The plug is a push fit into the socket when the electrical connection is made.

In this embodiment the strip contacts 35 and 39 extend up to the entrance of the socket and to the end of the shaft respectively. Consequently, the main and auxiliary contacts will be broken substantially simultaneously when the shaft is removed from the sleeve. In another embodiment, the strip contacts extend to different points along the longitudinal length of the sleeve and/or shaft such that various circuits may be broken in a specified order as the shaft is withdrawn.

Again, the insulating material 34 of the socket and the insulating material 40 of the plug are received in holes in the insulating moulding originally intended for a conventional pilot pin type plug and socket connector, and are retained therein by securing means.

In order to prevent a contact of a ridge of the splined shaft being connected with an incorrect contact in a channel in the splined sleeve, it may be desirable to alter the regular cross section of the plug and socket such that a pair of conductors may only be mated in the correct relative orientation. This could be done by widening or narrowing one or more of the channel/ridge pairs.

Thus, the invention provides a means of incorporating a multicontact pilot plug and socket in a single unit which can be used in spaces intended for known single contact pilot pin type plug and socket connectors without the need to modify the whole or any of the design parameters in a particular application which may be subject to National Standard design specifications.

The invention adheres to safety requirements by disengaging the main supply by pilot control circuit interruption where a plug is withdrawn by maintaining the safe length of pin insertion to ensure pilot circuit disconnection before the associated main plug current connections are disengaged.

According to the first embodiment of the invention up to four pilot cable connections can be made within the said safe length described above with sequential circuit interruption during withdrawal of the plug from the socket.

According to the third embodiment of the invention more than four pilot cable connections are possible within the safe length described above but with simultaneous circuit interruption during withdrawal.

However, sequential interruption is possible if the conductor lengths in the sleeve and/or on the shaft are not varied.

Claims (20)

1. An electrical connector comprising a plug which is receivable in a corresponding socket, a plurality of first electrical contacts, mutually insulated from one another, being located on the plug, and a corresponding plurality of second electrical contacts, also mutually insulated from one another, being located in the socket, each first contact being engageable with a corresponding second contact when the plug is fully received in the socket, wherein the second contacts are mounted on a movable member which is movable within the socket between a first position, in which each of the first contacts is not mutually engageable with its corresponding second contact, and the second position in which each of the first contacts is engageable with its corresponding second contact.

2. A connector as claimed in claim 1, wherein biassing means urge the second contacts to the second position.

3. A connector as claimed in claim 1 or 2, wherein the second contacts are movable along the direction of engagement of the plug the socket.

4. A connector as claimed in claim 1, 2 or 3, wherein the movable member is a movable plate.

5. A connector as claimed in claim 4, wherein the biassing means are a helical spring bearing on the plate.

6. A connector as claimed in claim 4 or 5, wherein each of the second contacts comprises a resilient finger adapted to engage a part of the plug which constitutes at least part of a corresponding first contact.

7. A connector as claimed in claim 6 wherein, the first contacts are in the form of coaxial rings on the plug.

8. A connector as claimed in claim 7, wherein at least one of the first contacts has a coaxial annular recess into which its corresponding second contact is received.

9. A connector as claimed in any of the preceding claims wherein a portion of the plug abuts the movable member when the plug is received in the socket.

10. An electrical connector substantially as specifically described herein with reference to figure 3 of the accompanying drawings.

11. An electrical connector comprising a plug which is receivable in a corresponding socket, a plurality of first electrical contacts; mutually insulated from on another, being located on the plug, and a corresponding plurality of second electrical contacts, also mutually insulated from one another, being located in the socket, each first contact being engageable with a corresponding second contact when the plug is received in the socket, wherein one of the plug and socket is formed with a plurality of ridges which extend generally in the direction of engagement of the plug with the socket and the other of the plug and socket is formed with a corresponding plurality of complementary channels, the first and second electrical contacts being located in and on the ridges and channels respectively.

12. A connector as claimed in claim 11, wherein the grooves and channels are straight.

13. A connector as claimed in claim 11 or 12, wherein the ridges or channels are constituted by internal and external splines.

14. A connector as claimed in claim 11, 12 or 13, wherein the first contacts are located on the ridges of the plug.

15. A connector as claimed in any one of claims 11 to 14, wherein the -contacts on the plug and/or socket are terminated longitudinally at differing points along the ridges and/or channels.

16. A connector as claimed in any one of claims 11 to 15, wherein the plug is formed with an external ledge which abuts the end of the socket when the plug is received in the socket.

17. A connector as claimed in any one of claims 11 to 16, wherein the plug and/or socket are of a onepiece moulded construction.

18. A connector as claimed in claim 17, wherein the contacts extend into the moulded plug and/or socket.

19. A connector as claimed in claim 18, wherein the connectors are incorporated within the material of the plug and/or socket during moulding.

20. An electrical connector substantially as specifically described herein with reference to figures 4, 5 and 6 of the accompanying drawings.