GB2306799A

GB2306799A - Gasket with peripheral flange for electrical connector

Info

Publication number: GB2306799A
Application number: GB9522052A
Authority: GB
Inventors: Bill Gascoigne
Original assignee: FLEXIBLE LAMPS Ltd
Current assignee: FLEXIBLE LAMPS Ltd
Priority date: 1995-10-27
Filing date: 1995-10-27
Publication date: 1997-05-07
Anticipated expiration: 2015-10-27
Also published as: GB9522052D0; GB2306799B

Abstract

A socket or a plug of an electrical connector comprises a body 12 having a rear opening affording access to the rearward end of the contact elements 30, a closure attachable to the body to close the rear opening, and a gasket 50 cooperable with the closure to seal the rearward ends of the contact elements from a cable entry aperture 66 provided in the closure. To obviate the additional O-ring previously used and to improve sealing performance generally, the gasket has a peripheral integral sealing flange 56 which is compressed between sealing surfaces on the closure and on the body as the closure is attached to the body.

Description

SEALS FOR ELECTRICAL CONNECTORS This invention relates to seals for electrical connectors.

The present invention is particularly, though not exclusively, suitable for connectors of the type used in articulated vehicles to connect the electrical systems of a towing vehicle such as a tractor unit and a towed vehicle such as a trailer. An example of an electrical connector to which the invention may be applied is an ABS connector used for anti-lock braking systems in articulated vehicles. The invention is not, however, limited to ABS connectors, which are referred to herein for illustration only: the invention may be used in other electrical connectors for use on vehicles and in other outdoor applications.

The design of ABS connectors is laid down in International Standard ISO 7638-1985 (E).

EP-A-O 544 630 discloses one of many examples of an ABS connector designed in accordance with that Standard.

Briefly, ABS connectors comprise a socket and a plug, the socket being fitted near the rear of a towing vehicle and the plug being fitted near the front of a towed vehicle. The socket and the plug respectively have generally tubular bodies containing contact elements, the socket containing cylindrical pins and the plug containing corresponding female contacts each capable of receiving an associated pin to form a connected pair of contact elements.

When connected, the bodies are coupled to one another axially with the open front part of the plug body fitting into the front opening of the socket body, this movement connecting aligned pairs of contact elements to one another with the front part of each pin fitting into the front part of a respective female contact. The connected bodies are then latched together.

The coupled bodies seal against each other to keep water, dirt and other contaminants away from the front parts of the contact elements. Sealing is aided by an O-ring positioned either within the socket body to seal against the front edge of the plug body or outside the plug body to seal against the front edge of the socket body. However, when not in use and thus uncoupled, the front openings of the plug body and the socket body must be covered to prevent the ingress of contaminants. In the case of the plug, this is achieved by inserting the plug into a dummy socket whilst, in the case of the socket, this is achieved by a hingeable cover that is biased into a closed position to cover the front opening.

The rear parts of the plug body and the socket body are also open so as to provide access to the rear parts of the contact elements for the attachment of cables or, in the case of EP-A-0 544 630 and similar arrangements, to receive the separate contact units that carry the contact elements. Again, the rear openings of the respective bodies must be closed to exclude contaminants and this is achieved by a screw-on cap which covers the rear end of each body. The cap associated with the plug may also incorporate a cable clamp to prevent the cable being pulled away from the contact elements in the event that the cable is used, incorrectly, to pull the plug out of the socket.

The cap has a hole to admit the end of the cable that is connected to the contact elements. As shown, for example, in Figures 1 and 2 of EP-A-0 544 630 (and referring to the numbering used therein), this hole is sealed from the contact elements by a discshaped elastomeric gasket lia that has a series of holes lib to accommodate electrical leads. The gasket fits within the closing component (cap) 11 and seals against the interior of the cap, a peripheral frusto-conical lip lic being provided around the gasket 11 to improve sealing with the correspondingly-shaped cap.

As shown in Figure 2 of EP-A-0 544 630, the cap 11 is also sealed by an O-ring where it meets the body 3 of the socket 1. The O-ring is presumably retained on the threaded rear shank 5 of the body 3 by a circumferential groove, although this is not shown, and bears against a shoulder defining the start of the shank 5. The O-ring is therefore compressed by the cap 11 against the shoulder when the cap 11 is screwed onto the shank 5.

In the ABS connector disclosed in EP-A-0 544 630, the cap performs another function which is to retain the separate contact unit 12 in position within the body 3. As best shown in Figure 2 thereof, the cap 11 bears upon the edge of the contact unit 12, cooperating with a front inner stop flange 13 to lock the contact unit 12 axially within the body 3.

The sealing arrangement of EP-A-0 544 630 suffers from disadvantages which the present invention seeks to overcome.

Firstly, the external O-ring is exposed to damage or dirt which can reduce its sealing ability, and it can easily be displaced from its correct position or even fall off the body and be lost.

Secondly, the gasket provides a somewhat limited defence against the ingress of contaminants: if it is breached or, more likely, bypassed by failure of the O-ring seal, contaminants are free to attack the rear ends of the contact elements.

Furthermore, the use of two seals - a O-ring and a gasket - is an undesirable complicalion that increases material costs and manufacturing costs.

As it can be costly to re-tool for a major redesign and as such redesign may, in any event, fall foul of any International Standards governing the connector in question, the present invention aims to overcome the disadvantages of the prior art without necessitating a major redesign of the connector.

With these objects in view and from one aspect, this invention may be defined as a socket or a plug of an electrical connector, the socket or plug comprising a plurality of contact elements each having a forward end for conductive contact with a complementary contact element and a rearward end connectable to a cable, a hollow body having a rear opening affording access to the rearward end of the contact elements, a closure attachable to the body to close the rear opening, and a gasket cooperable with the closure to seal the rearward ends of the contact elements from a cable entry aperture provided in the closure, wherein the gasket includes a peripheral integral sealing flange positioned to be compressed between opposed formations on the closure and on the body as the closure is attached to the body.

The invention proposes a single gasket to perform the dual sealing functions that, in the prior art, require a separate O-ring and gasket. There is no longer any need to suffer the unreliability or cost of an O-ring.

Also, quite apart from its functional elegance and its economy of design, in terms of basic sealing ability the invention outperforms the combination of an O-ring and gasket employed by the prior art.

The closure will usually be in the form of a cap that receives a portion of the body, although this is not essential.

To avoid any risk of mechanical damage to the flange in normal use, it is preferred that the flange in shrouded by an external collar associated with the closure or with the body.

In a particularly advantageous development of this concept, the body includes a threaded rear portion cooperable with a threaded front portion of the closure to attach the closure to the body, and one of the threaded portions is carried by the collar. In this way, cooperating threads lie between the flange and the environment and so protect the flange.

Conveniently, the formation on the closure is a substantially forward-facing sealing surface and the formation on the body is a substantially rearward-facing sealing surface.

The sealing surfaces may be defined by at least one shoulder associated with the closure and/or the body.

Complementary formations can be provided on a rearward part of the gasket and the forward part of the closure to locate the gasket with respect to the closure, interengagement of these complementary formations improving the stability of the gasket. The formations can, for example, have a stepped profile.

A forward part of the gasket can also be shaped in various ways, with various benefits.

For example, the forward part could be shaped to encapsulate the rearward ends of the contact elements, to conform with a rearward part of a contact holder that supports the contact elements, or to seal against the rearward part of the contact holder. These proposals improve insulation, protection or strength.

In particularly beneficial arrangements, the rearward part of the contact holder is shaped to define a plurality of recesses, each associated with a respective contact element, and the forward part of the gasket is shaped to define a plurality of protrusions capable of entering the recesses. These arrangements enjoy improved sealing and better location of the gasket and, for optimum protection, the protrusions may be shaped to match the recesses.

The recesses are preferably defined by structures such as partitions that cooperate to define a supporting surface for the gasket; that supporting surface is preferably substantially planar to keep the gasket flat.

The invention also resides in a gasket for a socket or plug comprising a plurality of contact elements each having a forward end for conductive contact with a complementary contact element and a rearward end connectable to a cable, a hollow body having a rear opening affording access to the rearward end of the contact elements, a closure attachable to the body to close the rear opening, and a cable entry aperture provided in the closure, wherein the gasket includes means cooperable in use with the closure to seal the rearward ends of the contact elements from the cable entry aperture, and a peripheral integral sealing flange compressible in use between opposed formations on the closure and on the body.

In order that this invention may be more readily understood, reference will now be made, by way of example, to the accompanying drawings in which: Figure 1 is an exploded schematic perspective view of the major components of the socket part of an ABS connector; Figure 2 is an enlarged schematic sectional side view of the parts show in Figure 1 assembled together to form a socket; and Figure 3 is a schematic sectional perspective view corresponding to Figure 2 and showing electrical leads connected to the pin terminals of the assembly.

Referring initially to Figure 1, a socket 10 comprises a generally tubular circular-section body 12 of moulded plastics material. An external attachment flange 14 lying in a plane perpendicular to the longitudinal axis of the body 12 is moulded integrally with the body 12 and includes holes 16 (only one being visible in this view) for attaching the socket 10 to a vehicle structure.

The rear part of the body 12, to the left as shown in Figure 1, has an externally-threaded portion 18 which is slightly narrower than the non-threaded forward part of the body 12 and so defines a circumferential shoulder 20 at the junction between the rear and forward parts. The shoulder 20 is interrupted by stops 22 which are angularly spaced around body 12 and project rearwardly from the shoulder 20.

A circumferential ridge 24 is situated within the body 12 at a location slightly forward of the shoulder 20. The ridge 24 provides forward axial location for a separate contact holder 26 which is a generally cylindrical one-piece moulding dimensioned to be a close sliding fit within the rear part of the body 12. The contact holder 26 includes a longitudinal slot 28 which, upon assembly, receives a longitudinal ridge (not shown) within the rear part of the body 12 to fix the contact holder 26 in a desired angular orientation with respect to the body 12.

The contact holder 26 carries a plurality of contact elements, in this case pins 30 whose forward ends 30a project freely as shown and whose rearward ends 30b (one of which is visible) lie in a protected position within an annular skirt 32 moulded integrally with the contact holder 26 at its rearward end.

Partitions 34 extend radially inwardly from the skirt 32 and are angularly spaced around the skirt 32. The partitions 34 divide the rearward ends 30b of the pins 30 from one another, placing each end 30b in an individual sector-shaped recess, and extend rearwardly to a plane level with the rearmost edge of the skirt 32. A central tubular projection 36 also terminates in this plane, the projection 36 being the rearward part of a sprung ejector mechanism required by ISO 7638-1985 (E). The ejector mechanism does not form part of this invention and so need not be illustrated or described here.

As best shown in Figure 2 of the drawings, the contact holder 26 defines a plurality of apertures that each receive a pin 30. Each of the apertures is bounded at its rearward end by circumferentially arranged, equi-angularly spaced, resilient fingers 38 with inwardlyfacing teeth 40 which together form a resilient annular collar.

During assembly, the pins 30 are inserted in a forward direction from the rear of the contact holder 26. A frusto-conical shoulder 42 on the pin pushes the fingers 38 apart until, on further insertion, the shoulder 42 bears against a forward stop 44 and the teeth 40 engage behind a second shoulder 46 situated towards the rear of the pin. This positive snap-fit engagement provides adequate retention of the contact elements within the contact holder and has the advantage that both insertion of the contact elements into and axial and radial retention of the contact elements within the contact holder is achieved in a single assembly operation, which simplifies the manufacturing process and reduces costs. There is also less risk of the contact elements dropping out and becoming lost during the assembly process.This in turn leads to fewer defective components and increases production yields.

Pins 30 are suitably attached to electrical leads 48, as shown in Figure 3, by a crimping process and are preferably attached to the leads 48 before the pins 30 are fitted to the contact holder 26.

The next component of the socket assembly 10 is a circular gasket 50 moulded of elastomeric material. The gasket has a series of holes 52 angularly spaced in circular formation to accommodate the electrical leads attached to the pins 30.

A forward portion of the gasket 50 comprises a plurality of angularly-spaced protrusions 54. The protrusions 54 are shaped and dimensioned to cooperate with and fit within the recesses at the rear end of the contact holder 26. The protrusions 54 therefore include pils (not shown) at their forward ends to accommodate the ends 30b of the pins 30.

For optimum sealing, the protrusions 54 are preferably shaped closely to match the shape of the recesses as shown. In this way, when the socket 10 unit is assembled and the protrusions 54 are pushed into the respective recesses of the contact holder 26, the ends 30b of the pins 30 are individually encapsulated by or even embedded in elastomeric material, much to the benefit of insulation and protection from contaminants.

It will be noted that the co-planar termination of the skirt 32, the partitions 34 and the tubular projection 36 effectively defines a planar supporting surface for the gasket 50.

Also, the gasket is prevented from turning with respect to the contact holder 26 by virtue of the engagement of the protrusions 54 with the respective recesses within the skirt 32.

This very positive location and support holds the gasket 50 in an optimum flat sealing position and enhances the mechanical strength of the entire unit.

A flange 56, which may also be described as a rim or lip, extends around the periphery of the gasket 50 and approaches the external width of the threaded portion 18 of the body 12.

When the final part of the socket 10, namely a closure in the form of a cap 58 having an internally-threaded forward collar 60, is screwed onto the threaded portion 18 of the body 12 until the forward edge of the cap 58 bears against the stops 22 associated with the shoulder 20, the flange 56 of the gasket 50 is gently compressed between an internal shoulder 62 within the cap and the rearmost edge 64 of the threaded portion 18.

The flange 56 thereby enables a single gasket 50 to perform the dual sealing functions that, in the prior art, require a separate O-ring and gasket. In other words, the flange 56 prevents contaminants reaching the pins 30 either through the joint between the cap 58 and the body 12, or through the cable entry aperture 66 in the rear end of the cap 58.

Study of the drawings shows how the gasket 50 outperforms the combination of an O- ring and gasket employed by the prior art. For example, note from Figures 2 and 3 that contaminants entering the rearward end of the socket 10 through the cable entry aperture 66 cannot gain access to the pins 30 simply by penetrating around the edge of the gasket 50. Note also that the flange 56 is completely shrouded and protected by the collar 60 of the cap 58 and so cannot suffer from mechanical damage in normal use.

It will be evident, too, that the cooperating threads of the externally-threaded portion 18 of the body 12 and the internally-threaded collar 60 lie between the flange 56 and the environment and so will prevent most contaminants from reaching the flange 56 at all.

Such few contaminants as may make it through the threads will be unlikely to exert such pressure on the flange as to break its seal. Even if contaminants get past the flange 56, they have little chance of reaching the pins 30 in view of the labyrinthine path imposed by the protrusions 54 and their close sealing engagement with the skirt 32, partitions 34 and tubular projection 36 of the contact holder 26.

As best seen in Figure 2, the rearward peripheral part of the gasket 50 immediately behind the flange 56 has a stepped profile 68 shaped to match a complementary stepped profile within the cap 56. Interengagement of these complementary formations further improves the stability of the gasket and the mechanical strength of the entire unit.

It is reiterated that the invention can be applied to connectors other than ABS connectors and, although the invention has been described in relation to a socket, it will be clear to the skilled reader that the invention is equally applicable to a plug. It will also be clear that the contact elements could be female elements rather than pins, and that the contact holder could be integral with the body. Indeed, many variations are possible without departing from the scope of the present invention.

There are, for example, many other ways of attaching the contact elements to the contact holder, not necessarily involving snap-fit connection. In one alternative embodiment, a resilient retaining element is associated with the contact element, which on insertion of the contact element into the contact holder, cooperates with an annular ridge formed in the contact holder to retain the contact element in position.

In another alternative embodiment, the resilient retaining element comprises a spring collar mounted on the contact element. This configuration is advantageous in that no toothed projections are required, thereby simplifying the design of the mould used to manufacture the contact holder. Additionally, this design achieves particularly strong retention of the contact elements within the contact holder.

In yet another alternative embodiment, the resilient retaining element comprises a barb formed integrally with the contact element. This reduces unit costs considerably at some cost in tooling expenditure. The manufacturing process is also simplified, since the contact element and resilient member can be manufactured simultaneously from e.g. a single piece of folded sheet metal. This eliminates the step of mounting the resilient retaining element on the contact element.

In general, the present invention may be embodied in other specific forms without departing from its essential attributes. Accordingly, reference should be made to the appended claims and other general statements herein rather than to the foregoing specification as indicating the scope of the invention.

Claims

1. A socket or a plug of an electrical connector, the socket or plug comprising a plurality of contact elements each having a forward end for conductive contact with a complementary contact element and a rearward end connectable to a cable, a hollow body having a rear opening affording access to the rearward end of the contact elements, a closure attachable to the body to close the rear opening, and a gasket cooperable with the closure to seal the rearward ends of the contact elements from a cable entry aperture provided in the closure, wherein the gasket includes a peripheral integral sealing flange positioned to be compressed between opposed formations on the closure and on the body as the closure is attached to the body.

2. A socket or a plug as defined in claim 1, wherein the flange in shrouded by an external collar associated with the closure or with the body.

3. A socket or a plug as defined in claim 2, wherein the body includes a threaded rear portion cooperable with a threaded front portion of the closure to attach the closure to the body, and wherein one of the threaded portions is carried by the collar.

4. A socket or a plug as defined in any preceding claim, wherein the formation on the closure is a substantially forward-facing sealing surface and wherein the formation on the body is a substantially rearward-facing sealing surface.

5. A socket or a plug as defined in claim 4, wherein the sealing surfaces are defined by at ]east one shoulder associated with the closure and/or the body.

6. A socket or a plug as defined in any preceding claim, wherein a rearward part of the gasket and the closure have complementary formations that locate the gasket with respect to the closure.

7. A socket or a plug as defined in any preceding claim, wherein a forward part of the gasket is shaped to encapsulate the rearward ends of the contact elements.

8. A socket or a plug as defined in any preceding claim, wherein a forward part of the gasket is shaped to conform with a rearward part of a contact holder that supports the contact elements and is integral with or separate from the body.

9. A socket or a plug as defined in claim 8, wherein the forward part of the gasket is shaped to seal against the rearward part of the contact holder.

10. A socket or a plug as defined in claim 8 or claim 9, wherein the rearward part of the contact holder is shaped to define a plurality of recesses, each associated with a respective contact element, and wherein the forward part of the gasket is shaped to define a plurality of protrusions capable of entering the recesses.

11. A socket or a plug as defined in claim 10, wherein the protrusions are shaped to match the recesses.

12. A socket or a plug as defined in claim 11, wherein the recesses are defined by structures that cooperate to define a supporting surface for the gasket.

13. A socket or a plug as defined in claim 12, wherein the structures define a substantially planar supporting surface for the gasket.

14. A socket or a plug as defined in any preceding claim, wherein the closure is a cap that receives a portion of the body.

15. A gasket for a socket or plug comprising a plurality of contact elements each having a forward end for conductive contact with a complementary contact element and a rearward end connectable to a cable, a hollow body having a rear opening affording access to the rearward end of the contact elements, a closure attachable to the body to close the rear opening, and a cable entry aperture provided in the closure, wherein the gasket includes means cooperable in use with the closure to seal the rearward ends of the contact elements from the cable entry aperture, and a peripheral integral sealing flange compressible in use between opposed formations on the closure and on the body.

16. A socket or a plug of an electrical connector, substantially as hereinbefore described with reference to or as illustrated in the accompanying drawings.

17. A gasket, substantially as hereinbefore described with reference to or as illustrated in the accompanying drawings.