Integrated overmolded cable seal and gasket for an electronic module

An electronic module includes a housing with at least two housing parts; a cable including a sheath end and a plurality of conductors extending from the sheath end; and a one-piece, multi-function seal between the cable and the housing. The multi-function seal includes a cable seal overmolded on the cable at the sheath end with the plurality of conductors being exposed from the multi-function seal. The multi-function seal further includes an integral gasket extending from the cable seal and positioned between at least two housing parts.

FIELD OF THE INVENTION

The present invention relates to electronic assemblies for use in work machines, and, more particularly, to electronic modules containing electronic circuit boards for use in such work machines.

BACKGROUND OF THE INVENTION

Work machines such as agricultural tractors, combines, construction and forestry equipment continually rely to a greater extent upon electronics and electronic controls. Work machines may operate in extreme environments compared to other applications. Among other concerns, it is necessary for on-board electronics to be designed from an electronics packaging standpoint with vibration, heat transfer and electromagnetic interference (EMI) in mind. Thus, electronics for work machines must be generally of a robust design.

When designing electronic modules that are to be embedded in an application such as a tractor or construction vehicle, it is critical that the mechanical packaging concept (the enclosure holding the electronic circuit boards) is sealed against possible exposure to the elements and designed to withstand high levels of vibration. For example, an electronic module mounted on the arm of a backhoe or trencher may be completely submersed in water for periods of time as the operator digs into swampy ground. Failure points for electronics modules in these situations include the seam between enclosure halves and any opening in the enclosure, such as the location where a cable exits the enclosure to connect to an external module. These potential trouble spots must be thoroughly sealed against the intrusion of moisture and dust. In addition, when a cable enters the module, it must be connected at some point to the printed circuit board inside the enclosure. This point of connection can be a potential failure point if the module is subjected to high levels of vibration and mechanical shock.

There are industry standard methods for addressing these potential failure points. To seal two halves of an enclosure against the environment, designers may use a pre-formed gasket (of silicone or similar material) sandwiched between the halves to prevent intrusion. Other methods include dispensing a bead of wet sealing material around the lip of one or both of the enclosure halves and pressing them together to form a seal. Although these same gasketing methods can be used around the opening where a cable exits the enclosure, it is more difficult to create a seal between the dislike materials of the enclosure and the cable. A technique called overmolding, in which a plastic or similar material is molded around wires to create a kind of protective shell can be used to create a cable that has a built in seal molded around it. This is a separate and additional process that must be used in addition to the gasket placed between the enclosure halves.

To address the issue of connecting a cable to a printed circuit board, it is often best to insert the incoming wires directly into preformed holes in the circuit board, and solder each independently, rather than try to use a connector that may vibrate the board during use. Unfortunately, this practice often requires hand placement of the individual wires in the holes, which is subject to error, and hand soldering. These manual practices are labor intensive and increase the cost of the module.

What is needed in the art is an electronic module which is easier and faster to assemble, and has less chance for assembly errors.

SUMMARY OF THE INVENTION

The invention in one form is directed to an electronic module, including a housing with at least two housing parts; a cable including a sheath end and a plurality of conductors extending from the sheath end; and a one-piece, multi-function seal between the cable and the housing. The multi-function seal includes a cable seal overmolded on the cable at the sheath end with the plurality of conductors being exposed from the multi-function seal. The multi-function seal further includes an integral gasket extending from the cable seal and positioned between at least two housing parts.

The invention in another form is directed to method of manufacturing an electronic module, including the steps of: overmolding a one-piece, multi-function seal over an end of an electrical cable having a plurality of conductors, the multi-function seal including a cable seal overmolded on the cable end with the plurality of conductors being exposed from the multi-function seal, the multi-function seal further including an integral gasket extending from the cable seal; positioning the multi-function seal on a first housing part such that the gasket overlies an edge of the first housing part; and positioning a second housing part on the gasket such that the gasket overlies an edge of the second housing part.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, and more particularly toFIGS. 1-3, there is shown an embodiment of an electronic module10which may be mounted to a structural member12of a work vehicle, such as an agricultural or industrial tractor, forestry equipment, etc. In the embodiment shown, electronic module10is in the form of a power distribution module which is mounted to structural member12, but could be in the form of a different type of electronic module mounted to structural member12. Structural member12can be any suitable structure for supporting electronic module10, such as a vehicle frame, chassis, body, bulkhead, boom arm, etc.

Electronic module10generally includes a housing14, a cable16and a one-piece, multi-function seal18. Housing14is a multiple piece housing including at least two housing parts14A and14B defining a housing interior20. Housing14may include more than two housing parts, depending upon the application. Housing parts14A and14B each include a mating cut-out22which are complimentary with each other to form an opening for receiving cable16.

Cable16includes a sheath end24and a plurality of conductors26extending from sheath end24(FIGS. 2-4). Conductors26are typically formed with an extruded, insulative covering, usually color coded for each conductor. Conductors26may be configured for carrying electrical power and/or data, depending upon the application.

Multi-function seal18is positioned between cable16and housing14. Multi-function seal18generally includes a cable seal28, gasket30and alignment head32(FIGS. 1-3,5and7). Cable seal28is overmolded on cable16at sheath end24and the plurality of conductors26are exposed from multi-function seal18as shown inFIG. 3(i.e., conductors26extend through cable seal28and are exposed outside multi-function seal18). Cable seal28includes an annular groove at the periphery thereof which seals with cut-outs22of housing14. Gasket30is monolithically integral with and extends from cable seal28. Gasket30is positioned and hermetically seals between at least two housing parts, such as housing parts14A and14B as shown inFIGS. 1 and 3.

Cable seal28also preferably includes an integral strain relief28A, defined by an extended portion extending away from housing14. Strain relief28A is also intimately bonded with sheath end24through overmolding.

Alignment head32is monolithically integral with cable seal28at an interior of housing14(FIGS. 2,3,5and7). Alignment head32is configured for aligning the plurality of conductors26in a predetermined orientation relative to each other. In the embodiment shown, alignment head32is configured for aligning the plurality of conductors26in a linear array of equidistantly spaced conductors extending from alignment head32. To assist in proper orientation of conductors26, a wire presenter34is overmolded (e.g., insert molded) within alignment head32(FIGS. 3,5and6). Wire presenter34includes a plurality of holes36, with each conductor26being positioned within a corresponding hole36. To further assist in proper orientation of conductors26, it is possible to form wire presenter34with color coded holes or labels which correspond to the color coded insulative coverings on conductors26.

Holes36in wire presenter34are positioned to align with respective solder holes38formed in a circuit board40carried within housing14(FIGS. 2 and 3). The ends of conductors26are soldered within corresponding solder holes38using suitable soldering techniques. Solder holes38are in turn coupled with traces and electrical components carried on circuit board40, which can vary depending upon the application.

Gasket30has an overall shape which corresponds to the peripheral adjoining edges of housing parts14A and14B, e.g., a generally rectangular shape in the embodiment shown. Gasket30has a generally H-shaped cross section allowing receipt of and sealing with each peripheral adjoining edge of housing parts14A and14B. Gasket30also optionally includes a plurality of locating features42extending from gasket30for locating circuit board40within housing14. In the embodiment shown, locating features42have a generally L-shaped cross section with the foot of each L used for locating and pressing against circuit board40. Suitable seats may be formed in the interior sidewall of housing part14A, or standoffs or the like may be used on the opposite side of circuit board40, to maintain a proper standoff distance from housing14. Alternatively, locating features42can be formed with a groove or the like for holding an edge of circuit board40. Of course, the size and shape of gasket30, locating features42and/or the peripheral adjoining edges of housing parts14A and14B can vary, depending upon the application.

During manufacture and assembly, the ends of conductors26are placed within respective holes36formed in wire presenter34. Wire presenter34is then inserted into a mold cavity. The mold is closed and a suitable plastic or other material is injected into the mold cavity to form the one-piece, multi-function seal18. The cable16with overmolded multi-function seal18(FIG. 5) is removed from the mold cavity. The ends of conductors26extending from alignment head32are placed in respective solder holes38and soldered in place on circuit board40. Circuit board40is placed within housing part14A and multi-function seal18is arranged such that cable seal28is positioned within cut-outs22and gasket30overlies and seals with the peripheral edge of housing part14A (FIG. 7). Housing part14B is then positioned on housing part14A such that gasket30overlies and seals with the peripheral edge of housing part14B (FIGS. 1 and 3). Housing parts14A and14B may be fastened together using suitable fasteners, snap fittings, etc. It will be appreciated that the particular sequencing of the manufacturing and assembly steps can vary depending upon the application.