ELECTRICAL CONNECTION BETWEEN AN ELECTRICAL CONDUCTOR AND A CONTACT ELEMENT

Abstract

A method for producing an electrical connection between an electrical conductor, which includes a plurality of individual wires, and a contact element. The electrical conductor is arranged in a contact portion of the contact element, and the contact portion and the electrical conductor are subsequently pressed together so that the contact portion surrounds the electrical conductor. A a plurality of mutually spaced elongate welded connections between the contact portion and the electrical conductor are produced by laser irradiation of the contact portion, or by laser irradiation of the electrical conductor through an opening in the contact portion. The elongate welded connections extend in an irradiation direction from an irradiated region of the contact portion, or from an irradiated region of the electrical conductor, through an entire cross-section of the pressed electrical conductor to a region of the contact portion opposite to the irradiated region, such that the electrical conductor is connected to this area of the contact portion; and the irradiated regions are arranged in the form of a grid.

Claims

1. A method for producing an electrical connection between an electrical conductor comprising a plurality of individual wires and a contact element, wherein the electrical conductor is arranged in a contact portion of the contact element, and the contact portion and the electrical conductor are subsequently pressed together so that the contact portion surrounds the electrical conductor, wherein by laser irradiation of the contact portion, or by laser irradiation of the electrical conductor through an opening in the contact portion, a plurality of elongate welded connections spaced apart from one another are produced between the contact portion and the electrical conductor wherein the elongate welded connections each extend in an irradiation direction from an irradiated region of the contact portion, or from an irradiated region of the electrical conductor, through an entire cross-section of the pressed electrical conductor to an area of the contact portion opposite to the irradiated region so that the electrical conductor is connected to this area of the contact portion, wherein the irradiated regions are arranged in a grid.

2. The method according to claim 1, wherein the elongate welded connections are spaced apart from each other for a majority of their length normal to the direction of irradiation.

3. The method according to claim 1, wherein a plurality of elongate welded connections are produced simultaneously, in particular by the same source of laser irradiation.

4. The method according to claim 1, wherein at least one irradiated region is offset with respect to another irradiated region normal to the longitudinal direction of the individual wires, so that the projection of all elongate welded connections onto a cross-sectional area of the electrical conductor located in the region of the elongate welded connections results in a continuous welded region in the transverse direction of the electrical conductor.

5. The method according to claim 1, wherein the degree of pressing of the individual wires is lower in a longitudinal region of the contact element where no irradiated regions are located than in a longitudinal region of the contact element where irradiated regions are located.

6. The method according to claim 5, wherein the different degree of pressing is produced by a pressing tool having a stepped contact surface.

7. The method according to claim 5, wherein the different degree of pressing is produced by a contact portion with cable lug claws of different lengths in the transverse direction.

8. The method according to claim 1, wherein the degree of pressing of the individual wires in a longitudinal region of the contact element where irradiated regions are located is greater than 70%.

9. The method according to claim 1, wherein the laser irradiation takes place in that tool in which the pressing takes place.

10. The method according to claim 9, wherein the position of the pressed electrical conductor is not changed between pressing and laser irradiation.

11. The method according to claim 1, wherein the production of an elongate welded connection takes less than 100 ms, in particular less than 80 ms, for example by 60 ms.

12. The method according to claim 1, wherein the diameter of an irradiated region is between 0.4 and 0.8 mm, in particular between 0.5 and 0.7 mm, preferably 0.6 mm.

13. The method according to claim 1, wherein the grid constant of the irradiated regions is between 0.8 and 1.2 mm, in particular between 0.9 and 1.1 mm, preferably 1 mm.

14. The method according to claim 1, wherein the largest diameter of an elongate welded connection is 0.7 to 0.9 mm, in particular by 0.8 mm.

15. A device for producing an electrical connection between an electrical conductor comprising a plurality of individual wires and a contact element, the device comprising a pressing tool with which the electrical conductor arranged in a contact portion of the contact element can be pressed with the contact element so that the contact portion surrounds the electrical conductor, wherein a device for laser irradiation is provided, which is designed to produce a plurality of elongate welded connections spaced apart from one another between the contact portion and the electrical conductor, wherein the elongate welded connections each extend in an irradiation direction from an irradiated region of the contact portion, or from an irradiated region of the electrical conductor in an opening in the contact portion, to a region of the contact portion opposite the irradiated region, so that the electrical conductor is connected to this region of the contact portion, wherein the irradiated regions arc arranged in a grid pattern.

16. A unit with an electrical conductor comprising a plurality of individual wires and a contact element, wherein the electrical conductor is arranged in a contact portion of the contact element and the contact portion and the electrical conductor are pressed together so that the contact portion surrounds the electrical conductor and an electrical connection exists between the electrical conductor and the contact element, wherein a plurality of mutually spaced elongate welded connections are present between the contact portion and the electrical conductor, wherein the elongate welded connections each extend in an irradiation direction from an irradiated region of the contact portion, or from an irradiated region of the electrical conductor in an opening in the contact portion, to a region of the contact portion which is opposite the irradiated region, so that the electrical conductor is connected to this region of the contact portion wherein the irradiated regions are arranged in a grid pattern.

17. The unit according to claim 16, wherein the elongate welded connections are spaced apart from each other for a majority of their length normal to the direction of irradiation.

18. The unit according to claim 16, wherein at least one irradiated region is offset from another irradiated region normal to the longitudinal direction of the individual wires, so that the projection of all elongate welded connections onto a cross-sectional area of the electrical conductor located in the region of the elongate welded connections results in a continuous welded region in the transverse direction of the electrical conductor.

19. The unit according to claim 16, wherein the diameter of an irradiated region is between 0.4 and 0.8 mm, in particular between 0.5 and 0.7 mm, preferably 0.6 mm.

20. The unit according to claim 16, wherein the grid constant of the irradiated regions is between 0.8 and 1.2 mm, in particular between 0.9 and 1.1 mm, preferably 1 mm.

21. The unit according to claim 16, wherein the largest diameter of an elongate welded connection is 0.7 to 0.9 mm, in particular around 0.8 mm.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0055] The invention will now be explained in more detail with reference to exemplary embodiments. The drawings are exemplary and are intended to illustrate the idea of the invention, but in no way to restrict it or even to reproduce it conclusively.

[0056] The figures show as follows:

[0057] FIGS. 1a-d show a first embodiment variant of a device for pressing and laser welding (FIGS. 1a-c), fora contact, element (FIG. 1d) having contact portions with cable lug claws of different lengths in the transverse direction,

[0058] FIG. 2. shows a perspective view of the device of FIGS. 1a-c,

[0059] FIGS. 3a-b show the device from FIGS. 1a-c in sectional view during laser welding,

[0060] FIG. 4 shows an enlargement from FIG. 3b,

[0061] FIG. 5 shows a top view of the contact element after laser welding,

[0062] FIG. 6 shows the contact element, after laser welding in a device according to FIGS. 1a-c,

[0063] FIGS. 7a-e show a second embodiment variant of a device for pressing and laser welding, wherein the pressing tool has a stepped contact surface,

[0064] FIG. 8 shows a contact element in the initial state, for a device for pressing and laser welding in a third embodiment variant,

[0065] FIG. 9 shows the contact element of FIG. 8, bent to receive the electrical conductor,

[0066] FIG. 10 shows the contact, element of FIG. 9 with electrical conductor,

[0067] FIG. 11 shows the contact element of FIG. 10, inserted in a device for pressing and laser welding in a third embodiment variant, viewed obliquely from below,

[0068] FIG. 12 shows the contact element, end the device of FIG. 11, seen from above at an angle,

[0069] FIG. 13 shows the device from FIG. 11 in the dosed state,

[0070] FIG. 14 shows the contact element of FIG. 10 crimped around the electrical conductor,

[0071] FIG. 15 shows the crimped contact element from FIG. 14 with laser irradiation,

[0072] FIG. 16 shows a possible arrangement of irradiated regions.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0073] FIGS. 1a-d show a first embodiment variant of a device for pressing and laser welding, wherein this device is designed for contact elements having contact portions with cable lug claws of different lengths in the transverse direction.

[0074] FIG. 1a shows a longitudinal section through the opened device. A contact element 2 (cable lug) is inserted into a lower part 1 of the pressing tool. By lowering the upper part 3 of the pressing tool, the contact portion 4 of the contact element 2, which contact portion 4 surrounds the electrical conductor 5, is pressed downwards, wherein the ends of the cable lug claws 6, 7 are pressed inwards into the conductor 5. In this way, the press or crimp connection is made in the form of a B-crimp.

[0075] In FIG. 1d the contact element 2 is shown in the state before crimping. Seen in its longitudinal direction, the contact element 2 here has a connection portion 8 with a round lug for further electrical connection and a contact portion 4 for pressing with the electrical conductor 5. The contact portion 4 is divided into two longitudinal sections with cable lug claws 6, 7 of different lengths in the transverse direction. The shorter cable lug claw 6 then surrounds an area of the conductor 5 which is closer to the connection portion 8 and which is additionally laser welded. Within the cable lug claw 6, therefore, a higher degree of compression results, for example higher than 70%, in particular higher than 80% or higher than 90%. Here, therefore, an open rope structure of the individual wires 9 of the conductor 5 is to be ensured. This can be seen in FIG. 1b, which shows a cross-section along line B-B in FIG. 1a. The individual wires 9 of the conductor 5 are shown below at this point, which still have a circular cross-section.

[0076] The longer cable lug claw 7 surrounds an area of the conductor 5 which is further away from the connection portion 8 and which is not laser welded. Within the cable lug claw 7, therefore, a lower degree or pressing is obtained, for example less than 80%. Here there are fewer intermediate spaces between the individual wires 9. This can be seen in FIG. 1c, which shows a cross-section along line C-C in FIG. 1a. Below, it can be seen that the individual wires 9 are pressed together to such an extent that they already have a rather hexagonal cross-section.

[0077] The contact surface 10 (see FIG. 1a) of the lower part 1 is straight here and therefore of the same design for both cable lug claws 6, 7. A laser part 11 is recessed in the upper part 3 so that it can be lowered.

[0078] FIG. 2 shows a perspective view of the device of FIGS. 1a-c, with the conductor 5 pressed but not yet welded.

[0079] FIGS. 3a-b show the device of FIGS. 1a-c in sectional view during laser welding, corresponding to the illustrations in FIGS. 1a and b. The laser part 11 includes or is connected to a laser as a source of radiation. By means of optics including lenses, mirrors, etc., the laser part can emit a laser beam in the direction of irradiation, in this case the vertical, and shift this laser beam horizontally along a grid while maintaining the vertical orientation of the laser beam. In this way, the laser beam can be directed successively in time to different, approximately point-shaped, irradiated regions. The laser beams 12 are shown here as thin lines. Alternatively, an optical system may be used to split the laser beam into a plurality of laser beams 12 which impinge simultaneously on the irradiated regions.

[0080] In FIG. 3a, two laser beams 12 are shown, each of which impinges on an irradiated region and there forms an elongate welded connection 14 in each case downwards into the conductor 5 and up to the cable lug claw 6 on the opposite side. In FIG. 3b, six laser beams 12 are shown accordingly, each of which impinges in an irradiated region and forms an elongate welded connection 14 there in each case downwardly into the conductor 5 and as far as the cable lug claw 6 on the opposite side. The elongate welded connections 14 extend substantially in the direction of irradiation, that is to say here vertically. They do not overlap or touch each other.

[0081] FIG. 4 shows an enlargement from FIG. 3b, where the elongate welded connections 14 are shown schematically and can be seen more clearly.

[0082] FIG. 5 shows a top view of the contact element 2 after laser welding, where the entry points of the laser beam 12 are each recognizable as an irradiated region 13. The irradiated regions 13 are regularly spaced from one another and form here a grid with rows of alternately six and five irradiated regions 13 extending in the transverse direction of the contact element 2, i.e. normal to the longitudinal direction of the individual wires 9 of the electrical conductor 5. Rows following successively in the longitudinal direction of the individual wires 9 or in the longitudinal direction of the contact element 2 are offset relative to one another in the transverse direction by half a grid constant.

[0083] FIG. 6 shows the contact element 2 after laser welding in the lower part 1 of the pressing tool, wherein the irradiated regions 13 on the surface of the contact, element 2 are visible here.

[0084] FIGS. 7a-e show a second embodiment variant of a device for pressing and laser welding, wherein the pressing tool has a stepped contact surface. FIG. 7a largely corresponds to FIG. 1a except for the fact that the contact surface 10 of the lower part 1 for the contact portion 4 here has a different height corresponding to the two longitudinal regions of the contact portion 4, thus forming two steps 15, 16. The cable lug claws 6, 7 may, but need not, be of the same length.

[0085] FIGS. 7d and 7e show the contact element 2 in the pressed state.

[0086] FIG. 7b corresponds to FIG. 1b and has the same degree of pressing, FIG. 7c corresponds to FIG. 1c and has the same degree of pressing.

[0087] The cable lug claw 6 surrounds an area of the conductor 5 which is closer to the connection portion 8 and which is additionally welded with the laser. Within the cable lug claw 6, a higher degree of pressing results, for example higher than 70%, in particular higher than 80% or higher than 90%, due to the step 15 being located further down. Here again an open rope structure of the individual wires 9 of the conductor 5 is ensured, the individual wires 9 still have a circular cross-section as in FIG. 1b.

[0088] The cable lug claw 7 again surrounds an area of the conductor 5 which is further away from the connection portion 8 and which is not welded with the laser. Within the cable lug claw 7, therefore, a lower degree of pressing results, for example less than 80%. Here there are fewer intermediate spaces between the individual wires 9, the same as in FIG. 1c below, where the individual wires 9 are pressed together to such an extent that they already have a rather hexagonal cross-section.

[0089] Following the pressing, laser welding takes place in the device according to FIGS. 7a-c as in FIGS. 3a-b and 4, with the same result as in FIGS. 5 and 6.

[0090] FIGS. 8-15 show a third embodiment variant of the invention, wherein the pressing tool here does not have a stepped contact surface. The two cable lug claws 6, 7 of the contact element 2 are here of equal length.

[0091] The contact element 2 in FIG. 8 again has a contact portion 4 and a connection portion 8. The contact portion 4 comprises on both sides two cable lug claws 6, 7, here of equal length, which are separated from each other by a slot which, in the pressed state of the contact element, forms an opening 17 through which the surface of the pressed electrical conductor 5 remains accessible. A corrugation between the two cable lug claws 7, which are further away from the end of the electrical conductor 5 than the cable lug claws 6, serves to secure the electrical conductor 5 against being pulled out of the contact element 2 in the longitudinal direction of the electrical conductor 5. The cable lug claws 6, 7 could also be of different lengths according to the embodiment variants in FIGS. 1 to 7.

[0092] In FIG. 9, the cable lug claws 6, 7 are already bent towards each other so that an electrical conductor 5 can be inserted between them, as shown in FIG. 10. The insulation of the electrical conductor 5 is removed in the area of the cable lug claws 6, 7. Unlike the embodiment variants of FIGS. 1-7, here the cable lug claws 6, 7 are bent upwardly relative to the connection portion 8. The ends of the cable lug claws 6, 7 are then pressed into the electrical conductor 5 from above during crimping, see FIGS. 11-13. In embodiment variants 1-7, the cable lug claws 6, 7 are pressed into the electrical conductor 5 from below.

[0093] In FIGS. 11 and 12, electrical conductor 5 and contact element 2 are inserted into the lower part 1 of a pressing tool. By lowering the upper part 3 of the pressing tool, see FIG. 13, the contact portion 4 of the contact element 2, more precisely its cable lug claws 6, 1, is pressed inwards and then downwards, wherein the ends of the cable lug claws 6, 7 are pressed inwards into the conductor 5. In this way, the press or crimp connection is made in the form of a B-crimp.

[0094] The upper part 3 has a recess 18 extending transversely to the longitudinal direction of the electrical conductor 5, which recess is aligned with the slot which later forms the opening 17 of the contact portion 4, so that laser beams 12 can be sent onto the surface of the electrical conductor 5 from above through this recess 18 and the opening 17. In this embodiment variant of the invention, the laser beams 12 thus strike the contact element 2 from the side with the ends of the cable lug claws 6, 7, whereas in the embodiment variants according to FIGS. 1-7 the laser beams 12 strike the opposite side of the contact element 2.

[0095] In FIG. 13, the pressed electrical conductor 5 is shown in the closed pressing tool comprising the upper part 3 and the lower part 1.

[0096] FIG. 14 shows the pressed electrical conductor 5 with pressed contact element 2 without pressing tool. With respect to the contact portion 4, seen in the longitudinal direction of the individual wires 9, the opening 17 is closer to the connection portion 8 than to the end of the contact portion 4 facing away from the connection portion 8. The opening 17 extends in the transverse direction of the contact element 4, i.e. normal to the longitudinal direction of the individual wires 9, over the entire width of the pressed electrical conductor 5. This ensures that each individual wire 9 is covered by an elongate welded connection 14.

[0097] FIG. 15 shows the process of laser irradiation on the crimped electrical conductor 5 of FIG. 14. This process takes place in the pressing tool 1, 3, following the pressing of the electrical conductor 5, the position of which does not change. The laser beams 12 are arranged in a grid pattern and impinge normally on the surface of the individual wires 9 exposed in the opening 17. The grid-shaped arrangement of the laser beams 12 here comprises three parallel rows which extend normally to the longitudinal direction of the individual wires 9, wherein the middle row is offset from the two outer rows by half a grid constant. The outer rows here comprise, for example, eight laser beams, and the middle row comprises seven laser beams.

[0098] Accordingly, three rows of eight or seven irradiated regions 13 are formed in the opening 17 on the surface of the individual wires 9.

[0099] FIG. 16 shows a possible arrangement of irradiated regions 13 In a larger schematic representation. The irradiated regions 13 are arranged here in two rows of nine irradiated regions 13 each, which rows together cover a length L corresponding to the width of the pressed electrical conductor 5. The rows extend normally to the longitudinal direction of the individual wires 9. Within a row, the irradiated regions 13 have a spacing from one another which corresponds to the grid constant R. Between adjacent rows, the distance is half the grid constant R. Due to the diameter D of an irradiated region 13 which is greater than half the grid constant R, there is thus an overlap of the irradiated regions 13 of adjacent rows, i.e. an overlap in the longitudinal direction of the individual wires 9.

[0100] It is essential, however, that the projection of all the elongate welded connections 14 extending downwardly into the drawing plane from the irradiated regions 13 in FIG. 16 onto a plane extending normally to the drawing plane and parallel to the rows of irradiated regions 13 covers the entire cross-section of the pressed electrical conductor 5. This ensures that ail individual wires 9 are covered by on elongate welded connection 14.

[0101] The irradiated regions 13 here have a diameter D of 0.6 mm, and the grid constant R is 1 mm.

LIST OF REFERENCE SIGNS

[0102] 1 Lower part of the pressing tool

[0103] 2 Contact element (cable lug)

[0104] 3 Upper part of the pressing tool

[0105] 4 Contact portion

[0106] 5 Electrical conductor

[0107] 6 Cable lug claw

[0108] 7 Cable lug claw

[0109] 8 Connection portion

[0110] 9 Individual wire

[0111] 10 Contact surface

[0112] 11 Laser part (source of laser irradiation, device for laser irradiation)

[0113] 12 Laser beam

[0114] 13 Irradiated region

[0115] 14 Elongate welded connection

[0116] 15 Step

[0117] 16 Step

[0118] 17 Opening in contact element 2

[0119] 18 Recess In the upper part 3

[0120] D Diameter

[0121] L Length

[0122] R Grid constant