WO2013038126A1

WO2013038126A1 - Multi-part multiple pole coaxial electrical connector

Info

Publication number: WO2013038126A1
Application number: PCT/GB2012/000707
Authority: WO
Inventors: Philip Ross NORMAN
Original assignee: Robosynthesis Limited
Priority date: 2011-09-12
Filing date: 2012-09-11
Publication date: 2013-03-21
Also published as: GB2494638A; GB2494638B; GB201115776D0

Abstract

A multi-part multiple pole coaxial electrical connector (10) comprising two interengageable bodies (11a, 11b) of electrically insulating material each provided in a zone of engagement thereof with the other body with a coating of electrically conductive material. A first one (11a) of the bodies is formed in its zone of engagement with a sequence of three radially spaced-apart concentric electrically conductive plugs (13a, 13b, 13c) electrically insulated from one another at insertion ends thereof. The second one (11b) of the bodies is formed in its zone of engagement with a sequence of three radially spaced- apart concentric electrically conductive sockets (15a, 15b, 15c) electrically insulated from one another at entrance ends thereof. The centre plug (13a) is engageable with the wall of the centre socket (15a) to provide an electrical connection therewith forming a centre pole and each radially outer plug (13b, 13c) is engageable with and only with a radially outer wall of the corresponding radially outer socket (15b, 15c) to provide an electrical connection therewith forming a respective radially outer pole separated from the or each adjacent pole by an air gap (16).

Description

MULTI-PART MULTIPLE POLE COAXIAL ELECTRICAL CONNECTOR

The invention relates to a multi-part multiple pole coaxial electrical connector.

Electrical connectors exist in the most diverse forms and include coaxial connectors which are widely used in low voltage and low-amperage applications in such fields as telecommunications, television and computing. Coaxial connectors are usually constructed from metal or, at least, with metal pins and sockets embedded in or carried by a body of insulating material such as plastic. Also known - for example from US 6 375 512, which relates to a strip connector rather than a coaxial connector - are electrical connectors with conductors formed by coatings of electrically conductive material such as metal on an insulating material body. A difficulty inherent with connectors of this kind is that coatings have to be applied selectively, for example with use of masks, in order to confine the electrically conductive material to the specific areas where it is required and thus achieve mutual electrical insulation of conductors associated with different polarities. Masking can be complicated in the case of complex shapes and is inevitably time- consuming in the context of mass-production of low-cost items. This difficulty militates against economic production of multi-pole connectors with conductors formed by surface coatings of conductive material and preference continues to be given to use of separately constructed conductors such as pins and blades.

It is therefore the principal object of the present invention to address the difficulties involved with production of electrical connectors with surface coated conductors and to offer an economic alternative to conventional connector constructions with separately formed metal conductors carried by or embedded in insulating material casings.

Other objects and advantages of the invention will be apparent from the following description.

According to a first aspect of the present invention there is provided a multi-part multiple pole coaxial electrical connector comprising two interengageable bodies of electrically insulating material each provided in a zone of engagement thereof with the respective other body with a coating of electrically conductive material, a first one of the bodies being formed in its zone of engagement with a sequence of at least three radially spaced-apart concentric electrically conductive plugs electrically insulated from one another at insertion ends thereof and the second one of the bodies being formed in its zone of engagement with a sequence of at least three radially spaced-apart concentric electrically conductive sockets electrically insulated from one another at entrance ends thereof, the centre plug in the sequence of plugs being engageable with a radially outer wall of the centre socket in the sequence of sockets to provide an electrical connection therewith forming a centre pole and each radially outer plug in the sequence of plugs being engageable with and only with a radially outer wall of the corresponding radially outer socket in the sequence of sockets to provide an electrical connection therewith forming a respective radially outer pole separated from the or each other adjacent pole by an air gap.

Such a connector utilises the economically advantageous principle of creating electrical conductors by way of a coating of electrically conductive material on a body of electrically insulating material in the context of, in particular, a multi-pole coaxial connector, but without the need for expensive or complicated procedures to isolate regions of the coating specific to individual poles. The male conductors or plugs are electrically insulated from one another and the female conductors or sockets similarly insulated from one another by the expedient of electrically insulating ends, where masking can be carried out without difficulty or, even more simply, where selected areas of the electrically conductive material can be easily removed after application of the coating. The remaining problem of ensuring electrical insulation of each corresponding or mating plug and socket pair from each other such pair is dealt with by way of physical offsets, in particular by interengagement of each corresponding plug and socket at only a selected wall interface so as to achieve insulation by air gaps. It is thus possible to produce the electrically insulating material bodies with relatively complex shapes and to then comprehensively coat the zones of engagement of the bodies with the electrically conductive material without creating downstream difficulties in achieving mutual electrical isolation of the plug and socket pairs.

For preference, at least one of the plugs is engageable with the radially outer wall of the corresponding socket to provide a frictional connection of the bodies. The interengagement of at least one corresponding plug and socket thus assumes the additional function of coupling the bodies together, in particular by way of a frictional connection. This eliminates a need for separate fastening arrangements to maintain the bodies in an interengaged state. The security of an electrical interconnection and particularly also the frictional connection can be enhanced if at least one of the plugs conically tapers towards its insertion end and alternatively or additionally if at least one of the sockets conically widens towards its entrance end. A plug or socket having such a conical form enables a firm interference fit of co-operating surfaces of the plug and socket concerned. In that case it is advantageous if the plug and socket of a corresponding pair respectively conically taper and coaxially widen with substantially the same cone angle. This allows firm interengagement over a relatively large area and thus a secure electrical connection and strong frictional couple. Complementary cone surfaces of this kind also reduce demands on tolerancing and cones are inherently strong geometric structures suited to, for example, repeated engagement and disengagement of plugs and sockets when joining together and separating the two bodies. In the case of plugs and sockets formed or bounded by hollow cones, the cone wall may, through selection of a suitable constituent material, acquire a measure of resilience which can further assist the tightness of the electrical and frictional connections. Appropriately designed conical forms also help with removal from a mould in the case of moulded bodies.

In a preferred form of construction the plugs, apart from the radially outermost plug, are defined by blind recesses fully coated with the electrically conductive material. Similarly, the radially outer sockets can be defined by blind recesses fully coated with that material. In either case, the respective coating of electrically conductive material can thus be applied to an uninterrupted or continuous surface of the recesses including areas where such a coating is not actually needed. The applied electrical conductive material coating then forms a single homogeneous and uninterrupted layer. Exclusion of electrical conductivity in regions of the uninterrupted layer where this function is not needed is left to the insulating effect of the air gaps produced by the intermediate spaces or offsets in the interengagement of the plugs and sockets.

The electrically conductive material is preferably absent from the insertion ends of the plugs thereby to electrically insulate the plugs from one another at those ends. Similarly, the conductive material is preferably absent from the insertion ends of the sockets thereby to electrically insulate the sockets from one another at those ends. This represents the simplest means of electrically isolating the plugs from one another and the sockets from one another. In this connection, apart from constructional simplicity, it can be advantageous if the insertion ends of the plugs are coplanar and/or the entrance ends of the sockets are coplanar. Masking of the ends to prevent application of electrically conductive material or, especially, removal of applied material from those ends can then be carried out more easily.

The plugs and sockets are preferably circular in cross-section, which allows the bodies to be interengaged in any relative rotational orientation. The plugs and sockets can,, however, be of other cross-sectional shapes, such as corresponding polygonal forms, for example square or rectangular; in this regard, concentric in this specification signifies a common centre or axis, but does not imply circularity or rotational symmetry about that centre.

The electrically insulating material is preferably plastics material, especially a durable polymer offering rigidity of shape and good adhesion for an applied surface coating, and economic production of the bodies is favoured if the bodies are injection mouldings of the plastics material. The electrically conductive material is preferably a metallic material, especially a material with a high level of conductivity such as copper.

Current can be transmitted from the plugs and/or sockets by incorporation, in the respective body of insulating material, of an electrical conductor electrically connected with a respective plug or socket, as the case may be. Such a conductor can be, for example, a wire, pin or strip, which in the case of an injection-moulded body can be embedded in the body material at the time of moulding. The conductor can also be formed by a passage coated on the wall thereof with electrically conductive material connected with the electrically conductive material of the respective plug or socket, in which case the conductor can be formed at the same time as and integrated with the coating of the plug or socket concerned. This then removes the need for provision of a separate component such as pin or wire.

According to a second aspect of the present invention there is provided a method of producing a connector according to the first aspect, the method comprising the steps of producing each of the bodies from electrically insulating material, the bodies respectively defining the plugs and sockets in electrically non-conductive form, coating the plugs and sockets with an electrically conductive material so that the plugs and sockets become electrically conductive, and removing the electrically conductive material at the insertion ends of the plugs and the entrance ends of the sockets thereby to electrically insulate the plugs from one another and the sockets from one another.

The plugs and sockets are thus produced as integral shapes of the bodies of electrically insulating material and acquire their electrical conductivity solely by the application of the coating of electrically conductive material. The coating can cover the entire region of interengagement of the bodies and the mutual isolation of the plugs on the one hand and the sockets on the other hand achieved by removal of the coating material at the plug and socket ends. This represents a particularly simple and economic method of producing the connector bodies without resort to integration of separately constructed electrical conductors and without the need for selectively masking plugs and sockets during the coating procedure.

The step of producing preferably comprises moulding each of the bodies from plastics material, which offers the advantages already mentioned, and the step of coating preferably comprises plating the plugs and socket, with metallic material. Suitable electroplating processes are well-known in the field of metallisation of plastics. The step of removing the electrically conductive material from the plug and socket ends can be conveniently carried out by abrading, such as by face grinding.

An embodiment of the present invention will now be more particularly described by way of example with reference to the accompanying drawings, in which:

Fig. 1 is a schematic sectional scrap view of a multi-part coaxial connector embodying the invention, in which the parts of the connector are shown in disengaged or separated state;

Fig. 2 is a view similar to Fig. 1 , but showing the connector parts in interengaged state; and

Figs. 3a and 3b are end views, to reduced scale, of the connector parts again in disengaged state, respectively in the direction of the arrows 'a' and 'b' in Fig. 1.

Referring now to the drawings there is shown a multi-part multiple pole coaxial electrical connector 10 comprising two circular-section interengageable injection-moulded bodies 11a and b of electrically insulating plastics material. The bodies are essentially rigid, but the constituent plastics material may advantageously be such as to impart a limited degree of resilience to thinner-walled regions of either body. The bodies 1a, 11b are shown in separated state in Fig. 1 and interengaged state in Fig. 2.

The bodies 11a, 11b interengage by way of integrally formed interfitting shaped portions, as described further below, in zones of engagement of the bodies with one another and each body is provided in its respective zone of engagement with a coating 12 of electrically conductive material, in this instance copper. The coating 12 applied to each body is shown only in Fig. 1 of each and with exaggerated thickness. The coating can, in desired, continue into areas outside the zone of engagement, for example as shown on the outermost surface of the body 11b.

The body 11a is formed in its zone of engagement with the body 11b with a sequence of three radially spaced-apart concentric plugs 13a, 13b and 13c serving as part of the mentioned interfitting shapes. The centre plug 13a is solid with a cylindrical shank and a free end portion tapering conically inwardly towards the free or insertion end of the plug. The radially outer plugs 3b and 13c each have the form of a hollow cone, that of the plug 13b having a cylindrical bore and that of the plug 13c having a conical bore with a direction of taper opposite to that of the outer wall of the plug. The centre plug 13a and directly adjacent radially outer plug 13b are formed by blind recesses in the body 11a. These recesses, including their bases, are fully covered by the coating 12 of electrically conductive material.

The plugs 13a to 13c are made electrically conductive by the coating 12, but are electrically insulated from one another by absence of the coating at the free or insertion ends of the plugs. This absence is advantageously achieved in simple manner by removal of coating material formerly covering these ends, the removed material being indicated by the dotted line 12a. Removal of the material, for example by face grinding, is facilitated by the illustrated coplanarity of the insertion ends. The plugs could, however, have different axial lengths. Each plug is associated with a respective polarity and further plugs similarly with individual polarities can be added radially outwardly of the outermost plug 13c.

Electrical connections with the individual plugs within the body 11a can be achieved in various ways, including embedded pins, strips and wires, or, as shown by way of arbitrary example in Fig. 1 for the body 11a, formation of a passage 14 which is internally coated on its wall with the electrically conductive material of the coating 12 and which communicates with the base of one of the recesses and thus with one of the plugs, in this case the plug 13a.

Correspondingly, the body 11b is formed in its zone of engagement with the body 11a with a sequence of three radially spaced-apart concentric sockets 15a, 15b and 15c functioning as the remaining part of the mentioned interfitting shapes. The sockets respectively correspond or mate with the plugs 13a, 13b and 13c. The centre socket 15a is initially cylindrical and has, at spacing from the free or entrance end of the socket, a length portion tapering conically inwardly in a direction away from that end. The radially outer sockets 15b and 15c each have the form of a conical cavity and in similar manner to the plugs 13a and 13b are formed by blind recesses in the body 11b. Again, these recesses inclusive of their bases are completely covered by the coating 2 of electrically conductive material.

Like the plugs 13a to 13c, the sockets 5a to 15c are made electrically conductive by the coating 12 applied to the respective body 11 b and are again electrically insulated from one another by absence of the coating at the free or entrance ends of the sockets. This absence is also achieved by removal of coating material, analogously to removal of the material 12a at the body 11a, formerly covering these ends. The removal of the material such as by the mentioned face grinding is similarly assisted by coplanarity of the entrance ends of the sockets. Each socket is again associated with a respective polarity, in particularly that of the corresponding plug of the body 11a, and further sockets with individual polarities can be added in correspondence with any additional plugs.

The body 11 b also includes electrical connections (not shown) with the sockets and these can be in the form of one or other of the possibilities mentioned above for the body 11a.

A significant aspect of the connector is interengagement of the respectively corresponding plugs 13a to 13c and 15a to 15c - thus plug and socket pairs - in regions selected to exclude linking current paths represented by redundant areas of the electrically conductive coating, specifically areas which result from the simple and non-selective application of the coating to the entire zones of engagement of the bodies, but which should not participate in conduction. These paths otherwise have the capability to provide bridges between the individual poles. The exclusion is achieved, as evident from the Fig. 2 illustration of the bodies 11a and 11b in interengaged state, by diametral differences between the radially outer plugs 13b and 13c on the one hand and the radially outer sockets 15b and 5c on the other hand so that the plug 13b is engageable only with the radially outer wall of the socket 15b and the plug 13c is engageable only with the radially outer wall of the socket 15c. An air gap 16 is formed in each case between the radially inner surface, which is coated with electrically conductive material, of the cavity in each plug and a radially inner surface, which is similarly coated, radially inwardly bounding the respective socket. The air gaps ensure that each corresponding and mutually contacting plug and socket pair is electrically insulated from the remaining pairs and the poles thus remain isolated notwithstanding the presence of conductive coating areas not participating in the plug and socket connection. These areas can, however, be used for internal connections within the respective body, as shown in Fig. 1 by the passage 15.

The conicities of the mutually contacting surfaces of the plugs and sockets, including the tapered portions of the centre plug 13a and centre socket 15a, have the same angle so as to provide firm frictional engagement over a large area. This not only ensures a secure electrical connection, but also allows the bodies 11a and 11b to be coupled together solely by frictional couple.

The connector 10 can be manufactured in advantageous manner, as largely evident from the foregoing description, by injection the two bodies 11a and 1 b in final shape, comprehensively coating the zones of engagement of the bodies with electrically conductive material in an uninterrupted or continuous layer on each body, particularly by electroplating a thin layer of metal such as copper, and then abrading away, etching or removal by other mechanical or chemical means of the conductive material present at the insertion ends of the plugs and entrance ends of the sockets. Manufacture can thus be carried out simply and economically and the presence of superfluous areas of coating material potentially linking different polarities remains without influence due to the air gap insulations resulting from the selective contacting of the plugs and sockets.

Claims

1. A multi-part multiple pole coaxial electrical connector comprising two interengageable bodies of electrically insulating material each provided in a zone of engagement thereof with the respective other body with a coating of electrically conductive material, a first one of the bodies being formed in its zone of engagement with a sequence of at least three radially spaced-apart concentric electrically conductive plugs electrically insulated from one another at insertion ends thereof and the second one of the bodies being formed in its zone of engagement with a sequence of at least three radially spaced- apart concentric electrically conductive sockets electrically insulated from one another at entrance ends thereof, the centre plug in the sequence of plugs being engageable with a radially outer wall of the centre socket in the sequence of sockets to provide an electrical connection therewith forming a centre pole and each radially outer plug in the sequence of plugs being engageable with and only with a radially outer wall of the corresponding radially outer socket in the sequence of sockets to provide an electrical connection therewith forming a respective radially outer pole separated from the or each adjacent pole by an air gap.

2. A connector according to claim 1 , wherein at least one of the plugs is engageable with the radially outer wall of the corresponding socket to provide a frictional connection of the bodies.

3. A connector according to claim 1 or claim 2, wherein at least one of the plugs conically tapers towards the insertion end thereof.

4. A connector according to any one of the preceding claims, wherein at least one of the sockets conically widens towards the entrance end thereof.

5. A connector according to claim 4 when appended to claim 3, wherein the at least one plug and the at least one socket correspond and taper and widen, respectively, with substantially the same cone angle.

6. A connector according to any one of the preceding claims, wherein the plugs apart from the radially outermost plug are defined by blind recesses fully coated with the electrically conductive material.

7. A connector according to any one of the preceding claims, wherein the radially outer sockets are defined by blind recesses fully coated with the electrically conductive material.

8. A connector according to any one of the preceding claims, wherein the electrically conductive material is absent from the insertion ends of the plugs thereby to electrically insulate the plugs from one another at those ends.

9. A connector according to any one of the preceding claims, wherein the electrically conductive material is absent from the entrance ends of the sockets thereby to electrically insulate the sockets from one another at those ends.

10. A connector according to any one of the preceding claims, wherein the insertion ends of the plugs are coplanar.

11. A connector according to any one of the preceding claims, wherein the entrance ends of the sockets are coplanar.

12. A connector according to any one of the preceding claims, wherein the plugs and sockets are circular in cross-section.

13. A connector according to any one of claims 1 to 11 , wherein the plugs and sockets are of corresponding polygonal forms in cross-section.

14. A connector according to any one of the preceding claims, wherein the electrically insulating material is plastics material.

15. A connector according to claim 1 , wherein the bodies are injection mouldings of the plastics material.

16. A connector according to any one of the preceding claims, wherein the electrically conductive material is a metallic material.

17. A connector according to any one of the preceding claims, wherein at least one of the bodies incorporates an electrical conductor electrically connected with at least one of the plugs or sockets, as the case may be, of that body.

18. A connector according to claim 16, wherein the or at least one connector is formed by a passage coated on the wall thereof with electrically conductive material connected with the electrically conductive material of the respective plug or socket.

19. A method of producing a connector according to any one of the preceding claims, comprising the steps of producing each of the bodies from electrically insulating material, the bodies respectively defining the plugs and sockets in electrically non-conductive form, coating the plugs and sockets with an electrically conductive material so that the plugs and sockets become electrically conductive, and removing the electrically conductive material at the insertion ends of the plugs and the entrance ends of the sockets thereby to electrically insulate the plugs from one another and the sockets from one another.

20. A method according to claim 19, wherein the step of producing comprises moulding each of the bodies from plastics material.

21. A method according to claim 19 or claim 20, wherein the step of coating comprises plating the plugs and sockets with metallic material.

22. A method according to any one of claims 19 to 21, wherein the step of removing comprises abrading away the electrical conductive material.