Contact element for electrically interconnecting an electrical conductor and a connection part of an electrical system, and method for producing said element

Abstract

The invention relates to a contact element (2) for electrically contacting an electrical conductor (4) to a connection part (40) of an electrical system (42), in particular an electrical system of a motor vehicle, with the electrical conductor (4), which is sheathed with a conductor insulation (6), and with a cable lug (10, 10′, 10″, 10′″), which is connected in an electrically conductive manner to the electrical conductor (4) and comprises a contact part (11), wherein the cable lug (10, 10′, 10″, 10′″) and a section (14) of the electrical conductor (4) attached thereto are overmoulded with an electrically insulating housing (16) in such manner that a part (17) of the contact part (11) is exposed, wherein the housing (16) has a channel (20, 26), which runs from an opening (22, 28) of the housing (16) to the exposed part (17) of the contact part (11), and wherein a sealing element (30) is injection-moulded onto the housing (16) to seal a closure (44, 34), in particular a cover (34), which can be used to close the opening (22, 28). The invention further relates to a method for producing such a contact element.

Claims

1. Contact element for electrically contacting an electrical conductor, which is sheathed with a conductor insulation, to a connection part of an electrical system of a motor vehicle, the contact element comprising: a cable lug, which is connected in an electrically conductive manner to the electrical conductor and comprises a contact part; an electrically insulating housing made of a thermoplastic elastomer overmoulded upon the cable lug and a section of the electrical conductor attached thereto in such manner that a part of the contact part is exposed and wherein the housing has a first channel, which runs from a first opening of the housing to the exposed part of the contact part; a cover with which the first opening is closable, wherein the cover is formed at least partially of a harder material than the housing; and a sealing element injection-moulded onto the housing to seal the cover, wherein the sealing element and the cover are adapted to one another in such manner that the sealing element and the cover seal the first opening.

2. Contact element according to claim 1, wherein the conductor insulation consists of a thermoplastic elastomer, in particular thermoplastic polyurethane, and the housing consists of a thermoplastic elastomer, in particular thermoplastic polyurethane.

3. Contact element according to claim 1, wherein the cover is connected by a holding element to the housing so as to be undetachable.

4. Contact element according to claim 1, wherein the cover and the housing have complementary securing means for the frictional and/or positive fixing of the cover on the housing.

5. Contact element according to claim 1, wherein the electrical conductor and the cable lug are welded to one another, in particular ultrasonically welded.

6. Contact element according to claim 1, wherein the cable lug is crimped with the electrical conductor, preferably only in the non-insulated part of the electrical conductor.

7. Contact element according to claim 1, wherein the contact part of the cable lug has one or a plurality of openings through which the housing and/or the sealing element are injected.

8. Contact element according to claim 1, wherein the housing has a second channel which runs from a second opening of the housing to the exposed part of the contact part and wherein the sealing element is injection-moulded onto the housing at the first and/or second channel.

9. Contact element according to claim 8, wherein the sealing element injection-moulded onto the housing extends from the first channel through an opening of the contact part to the second channel.

10. Method for producing a contact element comprising: providing an electrical conductor, which is sheathed with a conductor insulation, and a cable lug, which is connected in a conductive manner to the electrical conductor and comprises a contact part; overmoulding the cable lug and a section of the electrical conductor attached thereto with a thermoplastic elastomer to produce an electrically insulating housing in such manner that a part of the contact part is exposed, wherein the overmoulding is carried out such that a channel is formed which runs from an opening of the housing to the exposed part of the contact part; injection moulding a sealing element onto the housing to seal a cover, which can be used to close the opening; and connecting the cover to the housing by a holding element, wherein the cover is formed at least partially of a harder material than the housing.

11. Method according to claim 10, wherein multi-component injection moulding is carried out, wherein in the overmoulding is a first injection moulding act in which the housing is produced and the injection moulding of the sealing element is a second injection moulding act.

12. Method according to claim 11, wherein the contact part of the cable lug has one or a plurality of openings which are filled with the material of the housing during the first injection moulding act.

13. Method according to claim 11, wherein the contact part of the cable lug has one or a plurality of openings which remain open during the first injection moulding act and are filled with the material of the sealing element during the second injection moulding act.

14. Contact element for electrically contacting an electrical conductor, which is sheathed with a conductor insulation, to a connection part of an electrical system of a motor vehicle, the contact element comprising: a cable lug, which is connected in an electrically conductive manner to the electrical conductor and comprises a contact part; an electrically insulating housing overmoulded upon the cable lug and a section of the electrical conductor attached thereto in such manner that a part of the contact part is exposed and wherein the housing has a first channel, which runs from a first opening of the housing to the exposed part of the contact part; a cover with which the first opening is closable; and a sealing element injection-moulded onto the housing to seal the cover, wherein the sealing element and the cover are adapted to one another in such manner that the sealing element and the cover seal the first opening; wherein the contact part of the cable lug has one or a plurality of openings through which the housing and/or the sealing element are injected.

15. Contact element according to claim 14, wherein the housing has a second channel which runs from a second opening of the housing to the exposed part of the contact part and wherein the sealing element is injection-moulded onto the housing at the first and/or second channel, wherein the sealing element injection-moulded onto the housing extends from the first channel through one of the opening(s) of the contact part to the second channel.

16. Method for producing a contact element comprising: providing an electrical conductor, which is sheathed with a conductor insulation, and a cable lug, which is connected in a conductive manner to the electrical conductor and comprises a contact part; overmoulding the cable lug and a section of the electrical conductor attached thereto with an electrically insulating housing in such manner that a part of the contact part is exposed, wherein the overmoulding is carried out such that a channel is formed which runs from an opening of the housing to the exposed part of the contact part; and injection moulding a sealing element onto the housing to seal a cover, which can be used to close the opening; wherein the overmoulding is a first injection moulding act in which the housing is produced from a material and the injection moulding of the sealing element is a second injection moulding act, wherein the contact part of the cable lug has one or a plurality of openings which are filled with the material of the housing during the first injection moulding act.

17. Method for producing a contact element comprising: providing an electrical conductor, which is sheathed with a conductor insulation, and a cable lug, which is connected in a conductive manner to the electrical conductor and comprises a contact part; overmoulding the cable lug and a section of the electrical conductor attached thereto with an electrically insulating housing in such manner that a part of the contact part is exposed, wherein the overmoulding is carried out such that a channel is formed which runs from an opening of the housing to the exposed part of the contact part; and injection moulding a sealing element onto the housing to seal a cover, which can be used to close the opening; wherein the overmoulding is a first injection moulding act in which the housing is produced and the injection moulding of the sealing element is a second injection moulding act in which the sealing element is produced from a material, wherein the contact part of the cable lug has one or a plurality of openings which remain open during the first injection moulding act and are filled with the material of the sealing element during the second injection moulding act.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the drawing

(2) FIG. 1a-b show an exemplary embodiment of the contact element,

(3) FIG. 2a-b show the contact element from FIG. 1a-b after establishing an electrical contacting with a connection part of an electrical system,

(4) FIG. 3a-b show an exemplary embodiment of the method for producing the contact element from FIG. 1a-b and

(5) FIG. 4a-d show cable lugs for different exemplary embodiments of the contact element.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

(6) FIGS. 1a-b show an exemplary embodiment of the contact element in an isometric view (FIG. 1a) and sectional view (FIG. 1b).

(7) The contact element 2 comprises an electric conductor 4, which is sheathed with a conductor insulation 6 made of quite soft polyurethane with the Shore hardness A80. One end 8 of the conductor 4 is stripped and connected by means of ultrasonic welding (in FIG. 1b illustrated schematically by two black bars) in an electrically conductive manner to a connection region 9 of a cable lug 10. The cable lug 10 has a flat circular contact part 11 with a central drill hole 12 and a plurality of smaller openings 13 arranged around it.

(8) The cable lug 10 and a section 14 of the electrical conductor 4 attached thereto is overmoulded with an electrically insulating housing 16 made of polyurethane, with a part 17 of the contact part 11 with the drill hole 12 being exposed.

(9) The housing 16 forms a first socket 18 with a first channel 20, which runs from a first opening 22 of the housing to the exposed part 17 of the contact part 11, and a second socket 24 with a second channel 26, which runs from a second opening 28 of the housing 16 to the exposed part 17 of the contact part 11.

(10) A sealing element 30 with circular sealing lips 31 is injection-moulded onto the housing 16 in the first and second channel 20, 26 which consists of a softer plastic than the housing 16, for example of thermoplastic polyethylene.

(11) A cover 34 is connected to the housing so as to be undetachable via a thread-shaped holding element 32. The cover 34 consists of a harder material than the housing, for example of polyamide and is latched via a positive connection with the end of the thread-shaped holding element 32.

(12) The shape of the cover 34 is adapted to the shape of the first support 18 such that the cover 34 can be placed on the first support 18 in order to close the opening 22.

(13) FIG. 2a-b show the contact element 2 from FIG. 1a after connecting to a connection part 40 of an electrical system 42 of a motor vehicle, namely in an isometric view (FIG. 2a) and in a sectional view (FIG. 2b). The connection part 40 has a slightly conical and electrically insulating base 44 with an electrically conductive threaded bolt 46 made of metal. When being connected, the contact element 2 with the second channel 26 is put over the base 44 such that the threaded bolt 46 is guided through the drill hole 12 of the contact part 11 of the cable lug 10. The threaded bolt can be secured with a nut 48 through the first channel 20.

(14) The sealing element 30 presses with the sealing lips 31 in the second channel on the outer side of the base 44 and, as a result, seals the contact element 2 from the second opening 28. The sealing from the first opening 22 takes place by placing the cover 34 on the first support 18, with the sealing element 30 pressing with the sealing lips 31 on the outer side of an inner contour 50 of the cover 34 and, as a result, causes a water-tight sealing.

(15) To securely fix the cover 34 on the housing 16, the cover 34 and the housing 16 have complementary securing means in the form of catch lugs 52 on the first support 18 and tabs 54 on the cover 34, and the catch lugs 52 can be snapped into the tabs 54 by rotating the cover 34 that is in place. As further complementary securing means, a locking element 56 is provided on the cover 34 and a corresponding undercut 58 is provided on the housing 16 which engage under one another when rotating the cover 34 and prevent accidental falling of the cover 34 from the housing 16.

(16) The contact element 2 enables a secure and tight contacting of the electrical conductor 4 with the connection part 40 of the electrical system 42. In particular, the overmoulded housing made of thermoplastic polyurethane leads to a tight connection with the conductor insulation 6. The material of the sealing element 30 that is softer compared to the housing 16 leads to good sealing of the exposed part 17 of the contact part 11 from both sides, and namely in particular in combination with the material of the cover 34 and of the base 44, which material is harder compared to the housing 16. The material of the housing 16 is, in contrast, hard enough to ensure a dimensionally stable housing and in particular to cause the positive securing of the cover 34 on the housing 16 by the catch lugs 52 and the undercut 56.

(17) It has been found that the contact part 2 has a higher degree of water-tightness (e.g. with respect to water and steam jet). The assembly of the contact part 2 and the connection part 40 attached thereto can even be submerged without water entering. Therefore, the contact part 2 is suitable in particular for applications in motor vehicles, in which it may be exposed to moisture and spraying water.

(18) A contact part connected to a connection part even allows this assembly to be submerged.

(19) FIGS. 3a-b illustrate an exemplary embodiment of the method for producing the contact element 2 from FIG. 1a in a schematic sectional representation.

(20) In a first step of the method, the conductor 4 sheathed with the conductor insulation 6 and attached to the cable lug 10 by ultrasonic welding is provided and is arranged in a first injection mould 80 as shown in FIG. 3a. A first injection-moulding step takes place in the injection mould 80, in which the cable lug 10 and the section 14 of the electrical conductor 4 attached thereto are overmoulded with the housing 16 made of thermoplastic polyurethane and namely in such manner that the part 17 of the contact part 11 with the drill hole 12 of the cable lug 10 remains exposed, the first and second base 18, 24 with the channels 20, 26 are produced and one or a plurality of openings 12 remain open.

(21) The structural part 82 produced in this way is then arranged in a second injection mould 84 as shown in FIG. 3b, in which a second injection moulding step is then carried out, where the sealing element 30 is moulded onto the housing 16.

(22) Through the previously open openings 13, the material injection moulded in the second injection moulding step can reach both sides of the contact part 11 without two-sided injection moulding being required. In this way, the production method is simplified.

(23) After the second injection moulding step, the separately produced cover 34 is connected to the holding element 32 to complete the contact element represented in FIG. 1a.

(24) FIGS. 4a-d show cable lugs for different exemplary embodiments of the contact elements in an isometric view.

(25) FIG. 4a shows the cable lug 10 of the contact element 2 from FIG. 1a. The cable lug has a flat connection region 9, in which the conductor 4 is welded on, and a flat contact part 11 with the central drill hole 12 for the threaded bolt 46 and the openings 13 arranged around it to inject through the sealing element 30. When producing the contact element 2, some of the openings 13 can also be injected in the first injection moulding step with the material of the housing 16 and thus filled with the material of the housing 16. In this way, an improved anchoring of the contact part 11 in the housing 16 can be achieved. Furthermore, some of the openings, as described in connection with FIG. 3a-b, can remain open during the first injection moulding step and can be injected in the second injection moulding step with the material of the sealing element 30, whereby the production of the contact element 2 can be simplified.

(26) FIG. 4b shows an alternative cable lug 10′, which differs from the cable lug 10 only by a different shape of the openings 13′ which are formed elongated in FIG. 4b, while the openings 13′ are formed round.

(27) FIG. 4c shows a further alternative cable lug 10″, which differs from the cable lug 10 only by a contact layer 90 applied on the connection part 9″, which improves the weld connection to the conductor 4. The contact layer 90 can for example be applied by friction coating.

(28) FIG. 4d shows a further alternative cable lug 10′″, which differs from the cable lug 10 only in that the connection region 9′″ is formed for a crimp connection. For this purpose, lateral crimp wings 92 are provided in the connection region 9′″ which are crimped around the strands of the conductor 4.

(29) The cable lug 10′″ is crimped with the electrical conductor 4 only in the stripped part of the electrical conductor 4. The insulation crimping normally used for the crimp connection is not required for a contact element produced with the cable lug 10′″ since sufficient stabilising of the crimping is achieved by the overmolded housing.