GB2151416A

GB2151416A - Sealing a moulded submergible electrical connector

Info

Publication number: GB2151416A
Application number: GB08430817A
Authority: GB
Inventors: Gary Lynn Villeneuve; David George Conners
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1983-12-09
Filing date: 1984-12-06
Publication date: 1985-07-17
Also published as: GB8430817D0; GB2151416B; JPS60136185A; DE3440400A1

Abstract

A moulded waterproof electrical connector comprises an elastomer grommet 15 stretched onto an insulated cable 16 adjacent an attached electrical terminal 18, and a body 12 formed by injecting a thermoplastic insulator material into the mould so as to surround and compress the grommet/wire and portions of the terminal. The thermoplastic material shrinks, when cooled from its molten state, so as to provide compression sealing of the interfaces between the wire insulation, grommet and body surfaces to prevent moisture propagation therealong. In addition, the body material is intimately moulded to the contours of the electrical terminal to provide a fixed restraint against its removal. <IMAGE>

Description

SPECIFICATION An insert molded submergible electrical connector BACKGROUND OF THE INVENTION Field of the Invention.

The present invention is directed to the field of electrical connectors and more specifically to the area of electrical connectors suitable for submerged use in a liquid environment.

Description of the Prior Art.

Moisture resistant type electrical connectors are prevalent in the prior art and generally utilize a hard molded plastic body in combination with a resilient material to provide a degree of sealing so as to prevent contaminants from causing corrosion of the electrical connection.

For instance, U.S. Patent 3,594,696 describes an electrical terminal connector assembly which includes a hollow housing and electrical terminals connected to respective insulated wires retained within apertures formed in the housing. The entire hollow housing is filled with a unitary mass of resilient molded material that embeds and retains the terminals therein. The unitary mass of material extends beyond the open end of the housing to form a flexible sealing lip when the connector is in a mating relationship with a like receptacle. The resilient material is also molded to extend beyond the apertured end of the housing so as to provide a limited moisture seal to those portions of the terminals and the wires extending therethrough.

While that prior art connector is useful to prevent air borne moisture and contaminants from reaching the terminal connections, it would not be suitable for use in a submerged environment since the unitary mass formed around the wires would allow moisture migration along the wires if any lateral movement of the wire occurs near the mass.

In another instance, commonly-assigned U.S. Patent 3,937,545 describes a waterproof electrical connector in which wire-connected electrical terminals, are slipped through a small apertured elastomer grommet and then forced into an associated hard shell connector housing until the terminals are located in apertures within the housing to a depth which allows locking detents to secure the terminals in place. The grommet is normally larger in diameter than the inside diameter of the connector housing so that when installed within the housing it is compressed to provide a water-tight seal at the interface between the inner surface of the connector housing and the outer surface of the grommet and also between the inner surface of the aperture of the grommet and the outer surface of the wire insulation.A removable plug is used to lock the detents in place against the terminals and prevent axial removal of the terminals from the connector. While the aforementioned electrical connector is effectively sealed to prevent moisture from entering the plug even when the plug is submerged, the assembly technique requires several operations which add to the cost of such a connector.

SUMMARY OF THE INVENTION The present invention is intended to provide a submergible waterproof electrical connector that is properly sealed against moisture contamination by utilizing a relatively inexpensive method of construction.

According to a first aspect of the invention there is provided a waterproof electrical connector as set forth in Claim 1 of the appended claims.

The invention further provides a method of forming a waterproof electrical connector as set forth in Claim 4 of the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described further, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a cross-sectional plan view, taken along I-I of Fig. 3, of a mated male and female connector set, wherein each connector contains the preferred embodiment of the invention; Figure 2 is an enlarged cross-sectional plan view of the elastomer sealing grommet; and Figure 3 is an enlarged end view of the connectors shown in Fig. 1.

DETAILED DESCRIPTION OF THE PRE FERRED EMBODIMENT The following description is made with reference to Figs. 1, 2 and 3 wherein identical elements are referred to by common character numbers.

The electrical connector of the present invention is illustrated in Fig. 1 embodied in both a female electrical connector 10 and a male electrical connector 40.

The female connector 10 includes a hard shell body 12 injection molded about an electrically conductive male terminal 18, that is permanently crimped or soldered to a corresponding wire 14 and also crimped to its insulated covering 16. The electrical terminal 18 is normally formed from stamped sheet metal that is rolled to define a necked down portion for sealing off the molten body material from the closed male contact portion 20 which extends from the housing 1 2 into an open-ended receptacle area 22. A grommet 15, formed of a resilient elastomeric material, such as silicone, is situated adjacent to the electrical terminal 18 and contains an aperture 1 3 through which the insulation 1 6 of the wire 14 extends.The aperture 1 3 of the grommet 1 5 has a maximum diameter which is less than the diameter of the wire insulation 16, so that during assembly, the grommet aperture 1 3 must be stretched and expanded to accept the insertion of the wire insulation 1 6 therethrough. The grommet 1 5 also contains circumferential ribs 1 7 disposed on its outer surface to increase its outer surface length and to provide added restraint and sealing. The housing 1 2 contains four locking ribs 6 which capture the grommet 15 and thereby to prevent any longitudinal movement with respect to the terminal 18.During the molding of the housing 12, a section of the mold abuts the end surface 11 of the grommet 1 5 to prevent longitudinal movement of the grommet with respect to the terminal 1 8.

That portion of the mold forms end surface 4 and allows molten material to flow around grommet 15 and form the locking ribs 6. The housing 1 2 is also formed to contain a conventional locking ramp 23 at its open end 24 to provide lock latching with a conventional deformable ring 30 on the male connector 40, when the connectors are mated.

The male connector, embodying the present invention, is shown as connector 40, wherein the hard shell housing 42 is shown as having an embedded electrical terminal 48 connected to a wire 44 and its insulator 46. The electrical terminal 48 defines a female electrical contact 1 9 apertured to receive the male contact portion 20 of the female connector 10. As in connector 10, the connector 40 contains an embedded elastomer grommet 1 5 surrounding the insulator portion 46 of the wire 44. The housing 42 is molded to surround the grommet 1 5 as indicated by locking ribs 6 that serve to retain the elastomer grommet 1 5 and prevent its longitudinal movement with respect to the terminal 48.

An O-ring seal 50 is employed in circular groove 47 on the housing 42 to provide a hermetic seal with the internal surface 26 of the connector 10, when the connectors are mated.

In forming each of the respective female and male connectors 10 and 40, unique molds are employed which provide housings 1 2 and 42 that are matable with predictable and acceptable tolerances. However, the molds contain common features whereby each elastomer grommet 1 5 is limited in its movement during the injection molding process, with respect to the electrical terminal (18 or 48), by mold portions that abut the end surface 11 of the grommet 1 5. The mold also allows for the formation of locking ribs 6 adjacent the end surface 11 so as to provide for retainment of the grommet 1 5 after the connector is removed from the mold.

The material employed to injection mold the hard shell body 1 2 is an insulative thermoplastic material that has the property of shrinking when cured by cooling. In this embodiment, nylon was found to be a suitable molding material for the body. The use of such a material having the shrinkage property is important in this invention since such shrinkage in combination with the mold pressure provides part of the compressive forces necessary to insure continuous sealing of the abutting wire/grommet/body surfaces against moisture propagation therealong.

Claims

1. A waterproof electrical connector attached to the end of an insulated wire comprising: means defining an electrically conducting terminal permanently connected to both an electrically conducting portion and an insulated portion of said wire; elastomer means having a central aperture therein of a diameter that is less than that of the insulated portion of said wire being expanded and positioned on said insulated portion of said wire adjacent said terminal means; and main body means formed by an injection molding method about the wire connected portion of said terminal and said elastomer means; wherein said injection molding method utilizes a molten thermoplastic material that shrinks in volume when cooled, to provide compressive forces against said terminal, said elastomer means and said insulation to thereby prevent moisture from entering said connector and reaching said terminal between said wire insulation and said main body means.

2. A waterproof connector as in Claim 1, wherein said main body means is formed to capture and retain said elastomer means.

3. A waterproof connector as in Claim 2, wherein said electrically conducting terminal contains either a male or female end opposite to the connection with said wire; said main body means is formed so as to allow for the mating of male and female ends of oppositely configured electrical connectors; and an elastomer sealing means is provided between the main body means of said mated connectors.

4. A method of forming a waterproof electrical connector including the steps of: providing an insulated wire; providing an electrically conductive terminal configured to be attached to said wire; providing an elastomer material having an aperture formed therein with a diameter that is less than the diameter of said insulated wire; stretching said aperture of said elastomer material and placing it around said insulated wire; attaching said terminal to the end of said insulated wire; providing a hollow body mold configured to surround a portion of said insulated wire, said elastomer material and a portion of said attached terminal, and to limit longitudinal movement of said elastomer material away from said terminal: : placing the portion of said insulated wire with said attached terminal and elastomer material into said hollow body mold; providing a quantity of molten thermoplastic material that cures and shrinks when cooled below its molten temperature; and injecting said quantity of molten thermoplastic material into said hollow body mold under pressure and subsequently curing said material to intimately form a protective body about the portion of said insulated wire with said attached terminal and elastomer material within said mold.

5. A waterproof electrical connector constructed substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.