AU653711B2 - Electrical connector and method of fabrication of an electrical connector - Google Patents

Description

COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952 COMPLETE SPECIFICATION (Original) 657 1 FOR OFFICE USE 711 Class Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: 0 0

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0 0000 Priority: Related Art: 03 9 0 0 00 *3 *0 0* NAME OF APPLICANT: ADDRESS OF APPLICANT: ACTUAL INVENTOR: ADDRESS FOR SERVICE: PACIFIC DUNLOP LIMITED 500 Bourke Street, Melbourne 3000, in the State of Victoria, Commonwealth of Australia John Anthony GASKELL DAVIES COLLISON, Patent Attorneys, 1 Little Collins Street, Melbourne, 3000.

0 0 00 *0 Complete Specification for the invention .entitled: ELECTRICAL CONNECTOR AND METHOD OF FABRICATION OF AN ELECTRICAL CONNECTOR The following statement is a full description of this invention, including the best method of performing it known to us: -1- 901212,vrsd1.004,paIfr,1 2- ELECTRICAL CONNECTOR AND METHOD OF FABRICATION OF AN ELECTRICAL CONNECTOR The present invention relates to an electrical connector and to a method of fabricating an electrical connector. It finds particular application in the fabrication of extension leads for use with mains electricity.

Plugs and sockets are known which are fabricated as a solid moulding of plastics material. The plastics material is moulded around the pins of a plug, or the 10 contacts of a socket, in a die. It is necessary to wait for the moulded plastics material to cool before removing the plug or socket from the die. This is a significant time factor in the fabrication process since a relatively large mass of material is present to S. be cooled.

0* It is known to reduce the cooling time by using an insert, a "pre-moulded slug", which is mounted on the pins of the plug or contacts of the socket prior to moulding. This means that an amount of material sufficient to mould a whole, solid plug no longer has to be cooled in a single cooling step. Instead the pre-moulded slug and a shell of plastics material can be moulded at different times, each 20 comprising significantly less material than the whole plug and therefore each cooling in a significantly shorter time.

However, there are difficulties in using a pre-moulded slug, these occurring .in particular where a socket is to be produced.

A socket and lead may have to be provided as a unitary item, for instance at the end of an extension lead. To provide electrical connection, a commonly used type of socket has three pairs of spring contacts between which the pins of a plug can be inserted to make electrical contact. The spring contacts are connected to the three wires of a mains carrying cable. Thus a plug inserted into such a socket is provided with mains electricity.

901212,vruspc.o.00Zpacf,2 -3- Known pre-moulded slugs comprise a block of plastics material having .three apertures therethrough. During moulding, the spring contacts of a socket are mounted in the three apertures, already connected to the wires of a mains cable. However, to ensure that the spring contacts will be correctly arranged in the finished socket, they are also mounted on mock pins during the moulding process.

Difficulty arises in assembling a pre-moulded slug about the spring contacts, as well as mounting the spring contacts on the mock pins, the spring contacts already being connected at their ends remote from the pins to the wires ,of a c:.ole. It is not 10 possible simply to slide the pre-moulded slug backwards along the cable so that the •spring contacts can be simply mounted on the pins before returning the pre-moulded slug to its final position since the outer covering of a cable necessarily comes very close to the pre-moulded slug, beyond which, or even close to whf:Qh, outer covering the slug cannot be moved.

To solve the problem of mounting a pre-moulded slug about the spring contacts of a socket and subsequently mounting the spring contacts on mock pins, known pre-moulded slugs tend to be shallow in depth so that the mock pins are relatively accessible to an operator mounting the spring contacts onto the pins within the slug.

However, a shallow pre-moulded slug means that the shell or outer layer of the socket must be relatively increased in terms of mass of material, this again tending to increase the cooling time before removal from a die. Further, it remains an awkward task to mount the spring contacts correctly on the mock pins, within the apertures of the slug.

An object of the present invention is to provide a method of fabricating an electrical connecting device in which preparation prior to moulding is relatively simple, and an electrical connection device having a pre-fabricated insert therein which has improved characteristics.

S01212vrnpc~Zpacifl43 -4- According to the present invention there is provided a method of fabricating an electrical connection device, the device comprising a plurality of connection elements connected to respective electrical supply elements, the connection elements being arranged at least partially within a body of insulating material, the method comprising the steps of connecting the connection elements to respective said electrical supply elements, mounting the connection elements on mounting means to hold the connection elements in a predetermined position in relation to each other, subsequently mounting a prefabricated insert in relation to the connection elements, the pre-fabricated insert comprising an insulative body having an aperture running through it, the aperture being shaped in cross section to accommodate at least part of the connection elements and to enable said supply elements to pass therethrough by means of which the insert can be slid along the supply elements to be mounted over said at least part of the connection .elements, such that the connection elements are at least partially enclosed by the prea, f-<s fabricated insert/and moulding an outer layer of the device about said pre-fabricated 15 insert to provide with said insert the body of insulating material.

The method of the present invention is particularly advantageous where the connection device comprises a socket, there being an array of connection elements for instance to receive the pins of a domestic plug. This array of elements will be held in 20 their relative positions by said mounting means during moulding of the outer layer.

e The pre-fabricated insert may at least partially enclose the connection element in the finished device.

A form of pre-fabricated insert which can be utilised to perform the above method comprises an insulative body having an aperture extending therethrough, the aperture being shaped in cross-section to accommodate at least part of said connection elements and supply elements where connected to a respective connection element, the aperture having a central portion to allow passage of said supply elements therethrough, and peripheral recesses about the central portion to accommodate the connection elements.

940",p:opaczmdunnop0m,4 4a Not only does this allow a relatively deep pre-fabricated insert to be used, but the very oepth of the insert can have the additional advantage of protecting a *9 9 9 9 9 .9 9 e *9 99 9 940903,p:\oamdu~apOI.cow4 connection between the connection elements and the supply elements, which latter may comprise wires of an electrical cable. This is a significant advantage over known arrangements where the depth of the pre-fabricated insert has to be minimised and the outer layer of material in the finished connection device which protects the connection between the connection elements and the supply elements tends to be thin. The connection can then be damaged through the material, and may finally be exposed.

A further advantage of pre-fabricated inserts in general is that the insert slug may comprise material known as "regrind". This material would otherwise be 10 disposed of, having unacceptable characteristics of colour or texture for use where it would be visible in a finished item.

0 Embodiments of the present invention will now be described, by way of example only, with reference to the following drawings, in which: #*so Figure 1 shows a perspective view of an extension socket according to a first embodiment of the present invention; *00* C Figure 2 shows a perspective view of a pre-moulded slug for use in the 20 extension socket of Figure 1;

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Figure 3 shows a step in fabrication of the extension socket of Figure 1;

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Figure 4 shows a further step in the fabrication of the extension socket of Figure 1; Figure 5 indicates yet a further step in the fabrication of an extension socket as shown in Figure 1; Figure 6 indicates a final stage in the fabrication of the extension socket of Figure 1; 9121,vr3p.Opa1W -6- Figure 7 shows an end view of a pre-moulded slug for use in the extension socket of Figure 1; Figure 8 shows a cross-section of the pre-moulded slug of Figure 6, taken on the line BB and viewed in the direction indicated by the arrows; Figure 9 shows a cross-section of the pre-moulded slug of Figure 6 taken on the line A and viewed in the direction indicated by the arrow; and 10 Figure 10 shows an end view of the other end of the pre-moulded slug with respect to Figure 6.

Referring to Figure 1, an extension socket 1 for use with mains electricity typically comprises a body portion 2 having a flat face 3 at one end and being electrically connected to a mains cable 4 at the other end. The flat face 3 is provided with receiving holes 5 into which the pins of an electrical plug can be inserted so that mains current delivered by the cable 4 is supplied to an electrical load attached to the

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to* plug (not shown).

*0 0 20 The spring contacts 6 may for instance be of standard type for use with any Australian two or three pin plug, and their location in the socket will then be 4 0 determined by the appropriate SAA standard.

0 It is known to mould the body portion 2 of the extension socket 1 as a solid moulding of plastics material about spring contacts and electrical leads thereto which provide the electrical connection between a plug inserted to the socket 1 and the cable 4.

Referring to Figures 1 and 3, the arrangement inside an extension socket 1 as shown in Figure 1 comprises spring contacts 6 connected to respective wires 7 of the mains cable 4. Each spring contact 6 is arranged in a receiving hole 5 of the 901212,vrupc.OO~ppdrrc6 -7extension socket 1, in. the finished product.

Referring to Figure 2, in order to reduce the cooling time necessary during fabrication by moulding of the socket 1, a pre-moulded slug 8 is mounted about the spring contacts 6 and their connection to the wires 7 before the outer layer of the body portion 2 of the extension socket 1 is moulded in place. This means that the final moulding step of the fabrication process substantially concerns the moulding of just a shell of plastics material about the electrical components and the pre-moulded slug 8, such a shell thkIafore being relatively quick to cool compared with the case 10 where the whole body 2 of the extension socket 1 is manufactured by a single moulding step.

*em Distinctively, in an embodiment of the present invention, the pre-moulded slug S. 8 is provided with an opening 9, wide enough to accommodate the width of the mains cable 4, and extending all the way up the side of the slug 8 in the longitudinal direction thereof. This opening 9 not only allows the socket fabrication process to be carried out more quickly, but also allows the pre-moulded slug 8 to display greater depth, this feature allowing an extension socket 1 of improved robustness to be fabricated.

Referring to Figures 3 to 6, the extension socket 1 is fabricated as follows.

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An array of mock electrical pins 10 is mounted on a flat surface 11 provided as part of a mould. Each of the spring contacts 6 is mounted on a respective one of the mock electrical pins 10. The spring contacts 6 so mounted are shown in Figure 4. Referring to Figure 5, the pre-moulded slug 8 is mounted on an attached mains cable 4, behind the wires 7 exposed at the end of cable 4. It can be so mounted by means of the opening 9. Subsequently, the pre-moulded slug 8 can be moved forward over the spring contacts 6, each contact 6 entering into an internal cavity of the slug 8 to which the opening 9 gives access. The slug 8 is then moved against the flat surface 11 to the extent that an array of small feet 12 on the end face of the slug 8 901212ZpeWOZpdfk7 -8allow. .Thus, the main body of the pre-moulded slug is placed with a slight gap between its end face and the flat surface 11. Once the slug is in position, an outer layer 13 of the extension socket 1 can be moulded in place. This outer layer 13 is moulded by known techniques, using a mould or die (not shown), and must be cooled before remocval of the die. However, since the outer layer 13 is relatively thin compared with the diameter of the cross-section of the body portion 2, it cools relatively quickly.

It can be seen particularly clearly in Figure 6 that the pre-moulded slug 8 10 extends not only over the spring contacts 6 but also over the connections between the spring contacts 6 and the wires 7 of the mains cable 4. Hence these connections are particularly well protected in the finished extension socket 1.

Also advantageously, the material of the pre-moulded slug may comprise any convenient material, and may well comprise "regrind", otherwise commonly disposed of in view of its poor visual characteristics, or texture.

Referring to Figures 7 to 10, the pre-moulded sing 8 is substantially cylindrical, being slightly tapered from end to end, and being provided with the small S. 20 feet 12 referred to above.

Viewed from an end, the slug 8 has an internal cavity throughout its length.

The cross section of this cavity is substantially an inverted as shown. When the slug 8 m noved forward into the position shown in Figure 6, a spring contact 6 is received in each arm 14 of that Y shape, and in the stem of the Y shape provided by the opening 9. The spring contacts 6 are guided by the arms 14 and stem of the cavity which are dimensioned to allow sliding motion of the contacts 6, but no play between the contacts and the various surfaces of said arms 14 and stem.

Referring to Figure 8, each arm 14 is provided with a pair of shoulders about half way along the length of the slug 8. Hence the cross-section of the arm 14 901212,vuspclOZpadfl.8 -9is narrower towards the smaller end of the slug 8. In use, the spring contact 6 which is received in each of the arms 14 seats against the pair of shoulders 15, this providing positive location of the slug 8 with respect to the spring contacts 6. This positive location is important in that it should not be possible for a user to suffer an electric shock because a finger has inadvertently accessed a live contact 6 via the open end of a receiving hole 5 of a socket in use. At least the live contacts 6 must therefore be sufficiently distant from the flat surface 11, for instance at least 2 or 3 mm, to avo,4 such access occurring.

10 Thus it can be seen that the use of the pre-moulded slug having an opening .along its length provides a simple technique by which an extension socket may be .I fabricated, with reduced cooling time. The same principle of fabrication may be applied to other devices, and in particular may be applied where a solid moulded plug o is to be fabricated. In this situation, again, the open sided slug has the advantage that it can be made deep relative to the total length of a plug since the pins of the plug can be inserted in mock sockets before the slug has to be moved into position. There is therefore no necessity for there to be access from one end of the slug to manoeuvre S.g. othe pins of the plug where they project at the other end of the slug.

20 It will be clear that many modifications might be made to connection arrangements and methods for their fabrication with regard to the embodiments described above, without departing from the spirit and scope of the present invention.

For instance, the cross-section of the opening through the length of a pre-moulded I slug may be substantially different from that described above and shown in the Figures without departing from the scope of the invention. This may for instance be appropriate where some number other than 3 of electrical connections or connection devices are to be protected by a moulded body, or where a different type of electrical connection is to be made.

Embodiments of the present invention may find application wherever an electrical device is to be encapsulated in mouldable material, the moulding step being 901212,vrpc 0 2,pdf.,9 completed subsequent to attachment of elements of the electrical device to other elements, such as the wires of a cable.

Although a pre-fabricated insert for use in embodiments of the invention may conveniently comprise a pre-moulded slug of plastics material, it is not essential either that the insert be made by moulding, or that it should comprise plastics material although generally it would be important that the material is electrically insulating.

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Claims (2)

11- THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS: 1. A method of fabricating an electrical connection device, the device comprising a plurality of connection elements connected to respective electrical supply elements, the connection elements being arranged at least partially within a body of insulating material, ihe method comprising the steps of connecting the connection elements to respective said electrical supply elements, mounting the connection elements on mounting means to hold the connection elements in a predetermined position in relation to each other, subsequently mounting a pre-fabricated insert in relation to the connection elements, the pre-fabricated insert comprising an insulative body having an aperture running through it, the aperture being shaped in cross section to accommodate at least part of the connection elements and to enable said supply elements to pass therethrough by means of which the insert can be slid along the supply elements to be mounted over said at least part of the connection elements, such that the connection elements are at least partially 15 enclosed by the pre-fabricated insertk and moulding an outer layer of the device about said pre-fabricated insert to provide with said insert the body of insulating material. 2. A method according to claim 1 wherein said connection elements comprise an array of connection elements in the electrical connction device which are held in their 20 reL,-ve positions during moulding of the outer layer by said mounting means. A pre-fabricated insert when used in the method according to claim 1 or 2, comprising an insulative body having an aperture extending therethrough, the aperture p being shaped in cross-section to accommodate at least part of said connection elements and supply elements where connected to a respective connection element, the aperture having a central portion to allow passage of said supply elements therethrough, and peripheral recesses about the central portion to accommodate the connection elements. 4. A prefabricated insert according to claim 3, wherein the aperture is open-sided in that an access opening to the aperture extends along the pre-fabricated insert by means of which the insert can be mounted over said at least part of the connection elements. 940801_pA-p jcmr.dunIop0I=,II

12- A pre-fabricated insert according to claim 3 wherein the access opening allows the insert to be mounted over the electrical supply elements and subsequently slid into position at or over the connection element prior to moulding of the outer layer of the device. 6. A pre-fabricated insert according to one of claims 3, 4 or 5, comprising regrind material. 7. A domestic electrical supply socket comprising an electrical connection device constructed according to the method of claim 1 or 2. 8. A method substantially as described hereinbefore with reference to any one of the accompanying drawings. 15 9. An electrical socket substantially as described hereinbefore with reference to any one of the accompanying drawings. o o rooo o° agog *0 oooo o o i* r DATED this 3rd day of August, 1994 PACIFIC DUNLOP LIMITED By its Patent Attorneys DAVIES COLLISON CAVE N1) OAi ~J~ 940803,p:\opcajcmdunlopO1.n,12