Electrical Connection System

The present invention relates to a connection arrangement for an electrical conductor to connect the conductor to electrical apparatus, and more particularly to such a connection arrangement which is water-proof, pressure-resistant, and suitable to connect, for example, electrical cabling or wiring to electronic components and sensors used in automotive applications in locations where the terminal portions of the cables and wires are exposed to moisture, shock, vibration, and varying pressures.

It is known to dispose a shrink tube over end sections, surrounding a cable conductor extending from a plastic bushing or plug; the shrink tube extends up to the bare end, of the conductors. The shrink tube covers the transition between the bare ends of the conductor and the conductor itself, which is surrounded with an insulating sheath and forms one cable element or wire of the line. A plastic bushing or plur, in turn, is extruded around the cable ends and the end section of a plastic jacket surrounding the cables, and is bonded with this jacket. The arrangement has a disadvantage; the ends of the conductors are not sufficiently moisture-proof. In the case of stranded conductors, the moisture can seep between the individual strands. Although this disadvantage can be eliminated by tinning the strands, still a seal relative to the shrink tube is attained only if the tinning produces good roundness of the conductor so that the shrink tube rests against it on all sides. However, embodying the known line connection by round tinning of the strands and sealing off the shrink tube is relatively labor- and cost-intensive.

It is an object to provide a connection arrangement, and electrical cable connectors which are immune to external ambient conditions detrimental to good electrical contacts and connections, and which can make, effectively, sealed electrical connections in the interior of a plastic housing, for example to a sensor element.

Briefly, the electrical wires have insulating material placed thereabout, for example sleeves, insulating enamel or the like.

The terminal end parts of the wires are bare, for connection to the electrical apparatus. An entrance bushing or plug is used to connect the wires into a housing. To seal the wires into the plug, the plug, or plastic bushing, as well as the adhering insulating layers on the wires, are made of materials which join together, for example by melting together during injection molding of the plug or bushing around the wires and their insulating layers, or by chemical interaction of the material of the insulating layers and the material of the plug or bushing. The result will be a bond between the cable, or its outer sheath, which is not only mechanically tight, but which forms what may be termed an internally thermally or chemically welded interconnection or juncture between the insulating material of the wires and the material of the plug or bushing, throughout the extent of engagement of the plug or bushing about the wire.

In accordance with a feature of the invention, and when the cables are stranded cables, solid wire ends are spliced to the stranded cables, the splice surrounded by the insulating layer and the splice, together with the insulating layer, encapsulated with the material of the plug or bushing which joins with the layer of insulating material. This prevents possible seepage of moisture between strands of the stranded wires or cables while securely retaining the outer jacket or sheath of the connecting line, and all the wires or cables within the joined layer of insulating material and the material of the bushing.

The arrangement according to the invention has the advantage that the intrusion of moisture between the electric conductor and the plastic bushing or, between the plastic bushing and the line jacket surrounding both it and the line ends, and between the line jacket and the housing surrounding is prevented. A plastic bushing can be insertion molded directly around the line. The result is a connecting line which is pressure-tight and moisture-proof and suitable for sensors which are located at exposed points in a motor vehicle (intended for example for an antiskid brake system or for digital motor electronics). A further advantage is mechanical strength of the connecting line which is easily attainable.

In accordance with a preferred feature of the invention, a solid end conductor is used, and a layer of a suitable melting thermoplastic or a reactive thermosetting plastic is applied on the insulation adhering to a portion of the cable, this plastic layer tightly bonding by melting or reacting with the thermoplastic or thermosetting plastic of the plastic bushing when the bushing is molded on. The plastic bushing bonds equally well with the line jacket, if a jacket-type line is to be used. It is furthermore possible to insert the line, with the plastic bushing molded around it, into a bore of the housing in which means for effecting sealing from pressure and moisture are provided between the housing and the plastic bushing.

Exemplary embodiments of the invention are shown in the drawing. Shown are:

FIG. 1, a first exemplary embodiment of the end of a connecting line having a pressure- and moisture-proof bushing, together with the electrical appliance connected therewith shown in simplified form and the bushing embedded in the insulation housing of the appliance; and

FIG. 2, a second exemplary embodiment of the connecting line having a pressure- and moisture-proof bushing, which is disposed in a bore of a housing structure.

FIG. 1 illustrates a first exemplary embodiment of the invention in which a connecting line is connected in a pressure- and moisture-proof manner to an electrical apparatus, or appliance, shown as a sensor. The connecting line 1 has two cables 2 and 3, which are surrounded by a common outer plastic jacket or sheath 4. The cables 2 and 3 comprise respective stranded conductors 5 and 6, which are embedded in associated insulating sheaths 7 and 8. The conductors 5 and 6 are blank or bare at one end 5a; 6a, that is the insulating sheaths 7 and 8 are stripped away at these ends. The bare conductor ends 5a and 6a are adjoined by sections 2a and 3a, respectively, of the cables from which the plastic jacket 4 has been removed. Solid conductors 9 and 10, respectively, are secured in an electrically conductive manner to the conductor ends 5a and 6a of the stranded conductors 5 and 6, being soldered or welded in place by way of example. One section of the solid conductor 9; 10 is coated with an adherent insulation 11; 12. The adherent insulation 11; 12 is a lacquer coating, by way of example. The adherent insulation 11; 12 prevents the spread of moisture at the periphery of the solid conductor 9 and 10. The solid conductor ends 9 and 10 serve to connect the line 1 to the electrical apparatus, shown schematically as a sensor 15.

The end of the connecting line 1 is inserted into a housing 13 of the electrical apparatus of insulating material in a pressure- and moisture-proof manner. The end of the connecting line 1 has a bushing 14 of a thermoplastic or thermosetting, i.e. duroplastic insulating material extruded around the end of the line 1. An injection molding form or die is suitably used. The selection of an insulating material is to be governed by also considering the level of heat resistance required, which in the case of such functionally critical appliances as sensors in motor vehicles must also be taken into consideration in addition to providing pressure- and moisture-proofing. The bushing 14 surrounds the end section of the outer plastic jacket or sheath 4, the protruding ends 2a and 3a of the cores 2 and 3 having the bared ends 5a and 6a of the stranded conductors 5 and 6 as well as the colid conductors 9; 10 secured to the stranded conductors 5;6, at least as far as to include a portion of the insulation 11; 12 adhering to them. In the areas where the solid conductors 9; 10 and the ends 5a; 6a of the conductors 5; 6 are joined, the bushing 14 surrounds the individual conductors 5a, 9 and 6a, 10 respectively.

The free ends of the solid conductors 9; 10 are also bared and connected in a manner known per se to a sensor 15 not shown in further detail. The housing 13 of the sensor 15 encloses, surrounds, and sheathes the connection zone between the connecting line 1 and the sensor 15. The housing 13 is also made of a thermoplastic or thermosetting, i.e. duroplastic insulating material.

In accordance with a feature of the invention, the materials of the bushing 14 and of the insulation 11, 12 are selected to intimately bond or to join together by melting together or by chemically reacting. The housing 13, also, preferably joins by melting or reacting with the bushing 14 and with the portion of the adherent insulation 11; 12 of the solid conductors 9; 10 which is not surrounded by the bushing 14. The use of the solid conductors 9, 10 with the adherent insulation 11; 12 as connecting ends of the stranded conductors 5; 6 offers a simple means of leading in a conductor in a pressure- and moisture-proof manner, for the insulation 11; 12 applied in an adherent manner to the solid conductors 9; 10 is, like the housing and the bushing, tightly bound in one portion to the bushing 14 and in the adjoining portion to the housing 13. The solid conductors 9; 10 furthermore assure that the connection ends of the connecting line 1 are sufficiently mechanically stable. Examples of suitable materials for the solid wires 9, 10 are fully annealed, lacquer-insulated magnet wires.

A particularly stable connection is attained if a further layer 11a, 12a, e.g. a melting thermoplastic layer, for instance polyamide, or a reactive thermosetting plastic layer, for instance polyester imide or epoxy, is additionally applied to the adherent insulating layers 11, 12.

FIG. 2 shows a second exemplary embodiment of the connecting line of the invention, which is removable from the apparatus. The line 16 is inserted together with a bushing 23, surrounding line 16 into a bore 25 of a housing 24 of the electrical apparatus in a pressure- and moisture-proof, yet releasable, manner. The connecting line 16 has an outer sheath or jacket 28, within which are two cables 17 and 18 having respective solid conductors 19 and 20, which are provided with individual adherent insulating sheaths 21 and 22, respectively. An enamel, or lacquer coating is suitable for insulation 21, 22. An additional layer of a suitable melting thermoplastic or a reactive thermosetting plastic may be applied to the adherent insulating layers 21, 22.

In accordance with the invention, the cables 17; 18, which are spaced apart from one another, are embedded in a cylindrical bushing 23 which enters into a pressure- and moisture-proof combination with the insulation 21; 22 or the additional plastic layer applied thereto. The housing 24 of the electrical apparatus is formed with a bore 25 having an annular groove 26. The apparatus may be a sensor, for instance for an antiskid brake system or a digital electronic system for an engine. A sealing ring 27 is disposed in the annular groove 26. The bushing 23 is inserted with the connecting ends 19a or 20a of the solid conductors 19 and 20 into the bore 25 and is surrounded, again in a pressure- and moisture-proof manner, by the sealing ring 27. The connecting ends 19a and 20a extending through the bore 25 may be connected in a manner known per se and not known in further detail with the electrical apparatus, not shown in further detail in FIG. 2. The connecting line 16 protrudes from the housing 24. The plastic jacket 28 surrounds and embeds the cables 17 and 18. Jacket 28, and hence cables 17, 18 are secure against pull-out from the bushing 23 by the bonding connection of jacket 28 with the bushing 23 when the bushing 23 is extruded.