Connection element, contact arrangement, and method for manufacturing a contact arrangement

Abstract

The invention relates to an electrically conductive connection element (3) for establishing a connection to a first contact part (1). The connection element (3) contains a substantially flat connection portion (6) with a weld surface (7) on which the connection element (3) can be welded to the first contact part (1) by means of ultrasound. At least one welding projection (8) extends from the weld surface (7) such that, at the start of welding, the welding projection (8) first comes into contact with the first contact part (1). The invention also relates to an electric contact arrangement (30). This contains an electrically conductive first contact part (1) and a connection element (3) according to the invention. The weld surface (7) of the connection element (3) is welded to the first contact part (1) by means of ultrasound. The invention also relates to a method for manufacturing such a contact arrangements (30), comprising the steps of: a) bringing the welding projection (8) of the weld surface (7) of the connection element (3) into contact with the first contact part (1), b) introducing ultrasound into the connection element (3) such that the welding projection (8) at least partially penetrates into the first contact part (1) and at least part of the weld surface (7) is welded to the first contact part (1).

Description

[0001] Connecting element, contact arrangement and method for producing a contact arrangement

[0002] The present invention relates to connecting elements, contact arrangements and methods for producing contact arrangements.

[0003] In the field of e-mobility, screw connections are increasingly being used to transmit high currents, for example, to attach contacts to busbars. Such screw connections ensure, among other things, the required resistance values ​​at elevated temperatures. To connect them to busbars, contact parts are often equipped with special designs, such as mechanical clamping elements, which serve to extend the screw range.

[0004] Contacts made of copper or copper alloys are typically used. Busbars, however, are increasingly being made of aluminum for weight and cost reasons. The problem with this approach is the flow behavior of aluminum, which occurs under the forces exerted by the screw connection. This reduces the screw tension and allows ambient media to penetrate into the gaps, which in turn leads to undesirably high electrical resistance at the contact points.

[0005] Against this background, a secure connection with high, reliably achievable mechanical strength values ​​is desirable. The invention is based on the object of achieving these advantages.

[0006] For this purpose, a first aspect of the invention relates to an electrically conductive connecting element for establishing a connection to a first contact part, for example to a busbar. The connecting element contains a substantially flat connecting section with a welding surface, to which the connecting element can be welded to the first contact part by means of ultrasound. The connecting element can be used as an intermediate piece, which can directly or indirectly establish an electrical connection between the first contact part and a second contact part.

[0007] According to the invention, at least one welding projection extends from the welding surface in such a way that the welding projection first comes into contact with the first contact part at the start of the welding process.

[0008] This inventive design requires less ultrasonic power at the beginning of the welding process, since the contact area between the connecting element and the first contact part is smaller than would be the case without the welding projection. Furthermore, the ultrasound can be directed into the contact area in a defined manner at the beginning of the welding process.

[0009] With a suitably selected material pairing of the first and second contact parts (see below), the welding projections penetrate at least partially into the first contact part during the welding process – unlike when welding plastic connecting elements, which melt under the influence of ultrasound. This penetration ensures a more firmly bonded connection, which reduces the electrical resistance and increases the mechanical strength of the connection. Contamination of the contact surfaces of the contact parts also has less of an impact on the quality of the connection.

[0010] Overall, the connecting element according to the invention enables a process-stable connection between the connecting element and the first contact part and thus also a higher process capability of the welding process. This allows low electrical resistances to be reliably achieved. Advantageously, the connecting element contains a metal (for example, it can be a plastic / metal hybrid component) and is preferably made of it. The metal can be, for example, copper, which can optionally be coated with nickel and / or silver.

[0011] The connecting section can have a through-opening extending along a longitudinal direction, and the welding surface can enclose this through-opening in a ring-shaped manner. A mechanical clamping element, such as a screw, can be passed through the through-opening, as explained further below.

[0012] However, embodiments in which the connecting section does not have a through-hole are also included. In these embodiments, the welding surface is also preferably annular. For example, the connecting section can be designed as a screw bolt or contact pin without a through-hole.

[0013] In some embodiments, an annular welding projection may be provided. Alternatively, several welding projections may be present.

[0014] In some embodiments, the connecting element contains two sections, namely a cylindrical section extending in a longitudinal direction from a first end of the connecting element to a second end of the connecting element, said section having a through-opening that is in particular also cylindrical, and a flange-shaped section extending radially outwards from the cylindrical section in the region of the first end, said flange-shaped section forming the connecting section. The outer surface of the cylindrical section can have a circular cross-section or alternatively, for example, a polygonal cross-section. The through-opening defines an inner surface of the cylindrical section, which can also have a circular cross-section or alternatively, for example, a polygonal cross-section.The cylindrical portion can be moved through a through-opening of the first contact part and allow the passage of a mechanical clamping element. In these embodiments with a cylindrical portion, it is further advantageous if the welding projection extends toward the second end.

[0015] In some embodiments, the cylindrical section has at the second end a pressing surface running perpendicular to the longitudinal direction, on which the connecting element can be pressed against a second contact part.

[0016] The welding projection can have a height along the longitudinal direction in the range of 0.1 mm to 0.5 mm, in particular in the range of 0.2 mm to 0.3 mm. In the radial direction—i.e., perpendicular to the longitudinal direction—it can have a width in the range of 1 mm to 3 mm, in particular in the range of 1.5 mm to 2.5 mm. Such dimensions have proven particularly suitable.

[0017] In some embodiments, the profile of the welding projection has a radially inner profile section and a radially outer profile section in a sectional plane, in particular in a sectional plane containing the longitudinal direction. The radially inner profile section and the radially outer profile section can meet at a tip where the welding projection has its maximum height.

[0018] The radially inner profile section of the welding projection can have an inner width in the radial direction, and the radially outer profile section can have an outer width in the radial direction. The ratio between the outer width and inner width is preferably in the range of 1:4 to 1:1, more preferably in the range of 1:1.5 to 1:2.5, in particular 1:2. Ratios in this range have proven particularly favorable.

[0019] It has also been shown to be advantageous if the radially inner profile section is straight and runs at an angle α to the welding surface, which is preferably in the range from 5° to 20°, preferably in the range from 8° to 15°. Alternatively or additionally, the radially outer profile section can be straight and run at an angle β to the welding surface, which is in the range from 10° to 30°, preferably in the range from 15° to 25°.

[0020] A further aspect of the invention is an electrical contact arrangement comprising an electrically conductive first contact part and a connecting element as described above. In the contact arrangement according to the invention, the welding surface of the connecting element is ultrasonically welded to the first contact part. The resulting advantages have already been explained above. Although this is advantageous, the entire welding surface does not necessarily have to be welded to the first contact part.

[0021] The first contact part can be, for example, a busbar, which may contain or consist of aluminum. If the first contact part contains or consists of aluminum, its otherwise disruptive flow behavior has the advantage of facilitating the penetration of the welding projection, thus even improving the bond.

[0022] Alternatively, the first contact part may contain or consist of another metal, such as copper. Also included are first contact parts that contain or consist of a metallized material, for example a metallized plastic known per se. Alternatively, the first contact part may be an electrically conductive, in particular metallic, coated material, such as an electrically conductive coated plastic or an electrically conductive coated ceramic.

[0023] For the reasons already explained, it is advantageous if the welding projection of the connecting element penetrates at least partially into the first contact part. If the first contact part contains or consists of aluminum, this advantage is particularly pronounced due to the flow properties of aluminum.

[0024] The contact arrangement according to the invention, comprising a first contact part and a connecting element, can be provided pre-assembled as a separate unit and connected to an electrically conductive second contact part during the assembly process. Until then, the welded connection also serves as a protection against loss of the connecting element.

[0025] The connection with the second contact part results in an extended contact arrangement which, in addition to the first contact part and the connecting element, contains the second contact part and a mechanical clamping element.

[0026] The connecting element may include a cylindrical portion extending in a longitudinal direction from a first end of the connecting element to a second end of the connecting element. Furthermore, the connecting element may include a flange-shaped portion extending radially outward from the cylindrical portion in the region of the first end, forming the connecting portion.

[0027] The cylindrical section can have at the second end a pressing surface which runs substantially perpendicular to the longitudinal direction and on which the connecting element is pressed against the second contact part. The cylindrical section can completely penetrate the through-opening of the first contact part. Advantageously, the pressing surface is in electrical contact, in particular in direct electrical contact, with the second contact part. In this way, electrical current can flow from the first contact part through the connecting element to the second contact part. This applies even if there is only an inadequate direct electrical connection or no direct connection at all between the first contact part and the second contact part. This is particularly advantageous if the first contact part is made of a material which tends to flow, such as aluminum.

[0028] A through-opening can be formed in the first contact part, and the second contact part can have a fixing opening. Then, the clamping element can penetrate the through-opening of the first contact part and a through-opening of the connecting element, in particular the cylindrical portion of the connecting element, in a longitudinal direction. Furthermore, the clamping element can be engaged with the connecting portion of the connecting element and the fixing opening such that the connecting portion, the first contact part, and the second contact part are clamped together in the longitudinal direction.

[0029] Alternatively, the contact arrangement can comprise a further clamping element having a fixing opening. In this variant, the clamping element can be engaged with the connecting portion of the connecting element and the fixing opening of the further clamping element such that the connecting portion, the first contact part, the second contact part, and the further clamping element are clamped together in the longitudinal direction.

[0030] The clamping element can be, for example, a screw with a head and a shaft with an external thread. The head of the screw can rest on the connecting section, preferably on the side facing away from the welding surface.

[0031] Side of the connecting portion. The shaft can penetrate the through-opening of the first contact part and the through-opening of the connecting element, in particular the sleeve-shaped portion of the connecting element. The external thread can engage with an internal thread present in the second contact part in order to effect the bracing in the longitudinal direction.

[0032] Alternatively, the external thread of the shaft can engage with an internal thread of another clamping element as described above to achieve longitudinal clamping. This eliminates the need for an internal thread in the second contact part, ensuring greater mechanical stability. In this variant, the additional clamping element can be a bushing.

[0033] Alternatively, the clamping element can also be designed as a rivet, for example.

[0034] The ultrasonic vibrations are preferably introduced on the side of the connecting section facing away from the welding surface. Advantageously, the welding surface is welded to the first contact part by means of torsional ultrasound, with the torsional vibrations preferably being directed around the longitudinal direction. Alternatively, longitudinal vibrations are also conceivable and encompassed by the invention.

[0035] The connecting element and / or the second contact part may contain or consist of a material different from the material of the first contact part. In particular, it may contain or consist of copper. However, the invention also encompasses embodiments in which the materials are identical.

[0036] In a third aspect, the invention also relates to a method for producing a contact arrangement according to the invention. This method comprises the steps: a) bringing the welding projection of the welding surface of the connecting element into contact with the first contact part, b) introducing ultrasound into the connecting element such that the welding projection at least partially penetrates the first contact part and at least part of the welding surface is welded to the first contact part.

[0037] Although this is advantageous, it is not necessary to weld the entire welding surface to the first contact part.

[0038] The ultrasound is preferably applied to the side of the connecting section facing away from the welding surface. Welding can be performed, for example, by torsional ultrasonic welding.

[0039] Furthermore, the method can include the following steps: c) passing a mechanical clamping element, in particular a shaft of a screw, in a longitudinal direction through a through opening of the first contact part, d) mechanically connecting the mechanical clamping element to the fixing opening of the second contact part in such a way that the first contact part and the second contact part are clamped together in the longitudinal direction, in particular by screwing an external thread of the shaft into a fixing opening of the second contact part.

[0040] This creates an extended contact arrangement which, in addition to the first contact part and the connecting element, contains the second contact part and the mechanical clamping element

[0041] The invention is explained in more detail below with reference to several exemplary embodiments and drawings.

[0042] Figure 1: a first contact element according to the invention in a lateral sectional view Figure 2: a first contact arrangement according to the invention with the connecting element from Figure 1 and a first contact part in a lateral sectional view;

[0043] Figure 3: the first contact arrangement according to the invention with a second contact part and a screw in a side sectional view;

[0044] Figure 4 : a second contact element according to the invention in a lateral sectional view

[0045] Figure 5: a second contact arrangement according to the invention with the connecting element from Figure 4 and a first contact part in a side sectional view;

[0046] Figure 6: the second contact arrangement according to the invention with a second contact part and a screw in a side sectional view;

[0047] Figure 7 : a third contact element according to the invention in a lateral sectional view

[0048] Figure 8: a third contact arrangement according to the invention with the connecting element from Figure 7 and a first contact part in a side sectional view;

[0049] Figure 9: the third contact arrangement according to the invention with a second contact part and a screw in a side sectional view;

[0050] Figure 10: a detailed view of a connecting element according to the invention in a side sectional view.

[0051] The connecting element 3 shown in Figure 1, which is made of copper, for example, contains a substantially flat connecting section 6 with a through-opening 22 and a welding surface 7 surrounding the latter in an annular manner. At least one welding projection 8, not shown to scale here, extends from the welding surface 7 in a longitudinal direction L. This can be a single annular welding projection 8. Alternatively, a plurality of welding projections 8 can also be provided.

[0052] Figure 2 shows an electrical contact arrangement 30, which includes an electrically conductive first contact part 1 and the connecting element 3 from Figure 1. The first contact part 1 can be a busbar. This can, for example, contain or consist of aluminum or a conductively coated ceramic. The first contact part 1 also has a through-opening 11.

[0053] To produce the contact arrangement 30 shown in Figure 2, in a first step a) the welding projection 8 of the connecting element 3 is brought into contact with the first contact part 1. In a further step b) ultrasound is introduced into the connecting element 3 in such a way that the welding projection 8 penetrates at least partially into the first contact part 1 and part of the welding surface 7 is welded to the first contact part 1. For this purpose, an ultrasonic sonotrode can be placed on the side of the connecting section 6 facing away from the welding surface 7. Advantageously, the sonotrode executes torsional oscillations with respect to the longitudinal direction L.

[0054] The prefabricated contact arrangement 30 according to Figure 2 can be connected to a second contact part 2 by means of a screw 4, so that the extended contact arrangement 30 shown in Figure 3 is created. The second contact part 2 has a fixing opening 12 which is provided with an internal thread (not shown graphically). It can, for example, contain copper or consist of copper. Alternatively, the internal thread can be formed not in the second contact part 2, but in an additional bushing, which then represents a further clamping element. To produce the extended contact arrangement 30 in Figure 3, in a method step c) a shaft 14 of the screw 4 is passed in the longitudinal direction L through the through-opening 11 of the first contact part 1.Subsequently, in a step d), an external thread (not shown graphically) on the shaft 14 is screwed into the fixing opening 12 of the second contact part 2, so that the first contact part 1 and the second contact part 2 are clamped together in the longitudinal direction L. The head 13 of the screw 4 rests on the connecting section 6 on the side facing away from the welding surface 7.

[0055] Due to the direct contact between the first contact part 1 and the second contact part 2, an electric current can flow directly from the first contact part 1 into the second contact part 2.

[0056] The connecting element 3 of the contact arrangement 30 shown in Figure 4 has a cylindrical section 5 extending in a longitudinal direction L from a first end 9 of the connecting element 3 to a second end 10 of the connecting element 3. Furthermore, it contains a flange-shaped section which extends radially outwards from the cylindrical section 5 in the region of the first end 9 and forms a connecting section 6. A welding projection 8, not shown to scale, extends in the direction of the second end 10 in such a way that it first comes into contact with a first contact part 1 at the start of welding (see Figure 5). In contrast to the exemplary embodiment shown in Figure 1, the connecting element 3 according to Figure 4 has a pressing surface 17 which is formed at the second end 10 of the cylindrical section 5 and which runs perpendicular to the longitudinal direction L.

[0057] The prefabricated contact arrangement 30 shown in Figure 5 is created by welding to a first contact part 1. The welding projection 8 has penetrated into the first contact part 1. The prefabricated contact arrangement 30 according to Figure 5 can be connected to a second contact part 2 by means of a screw 4, resulting in the extended contact arrangement 30 shown in Figure 6. For this purpose, the second contact part 2, which can be made of aluminum, for example, has a fixing opening 12 which is provided with an internal thread (not shown graphically). The head 13 of the screw 4 rests on the connecting section 6 on the side facing away from the welding surface 7.The shaft 14 penetrates the through-hole 11 of the first contact part 1 and the through-hole 22 of the cylindrical portion 5 of the connecting element 3, and an external thread (not shown graphically) of the shaft 14 engages the internal thread. Alternatively, the internal thread may be formed not in the second contact part 2, but in an additional bushing, which then represents a further clamping element.

[0058] In this exemplary embodiment, the first contact part 1 and the second contact part 2 are not in direct contact. However, a current flow is possible indirectly through the connecting element 3. The connecting element 3 is pressed against the second contact part 2 at the pressing surface 17.

[0059] Figures 7 to 9 show a further embodiment. Here, the second contact part 2 is in contact with the side of the connecting portion 6 of the connecting element 3 facing away from the welding surface 7.

[0060] Figure 10 shows an enlarged view of the geometry of a possible embodiment of the welding surface 7. Along a longitudinal direction L, the welding projection 8 has a height h which can, for example, be in the range from 0.2 mm to 0.3 mm. In the radial direction, it has a width c which can be in the range from 1.5 mm to 2.5 mm. In the plane of the drawing, the profile of the welding projection 8 has a radially inner profile section 19 and a radially outer profile section 20. The radially inner profile section 19 and the radially outer profile section 20 meet at a tip 21, at which the welding projection 8 has its maximum height h. In the radial direction, the radially inner profile section 19 of the welding projection 8 has an inner width a, and the radially outer profile section 20 has an outer width b in the radial direction.The ratio of outer width b to inner width a can range from 1:1.5 to 1:2.5. The radially inner profile section 19 is rectilinear and extends at an angle α to the welding surface 7, which is in the range of 8° to 15°. The radially outer profile section 20 is also rectilinear but extends at an angle β to the welding surface 7, which is in the range of 15° to 25°.

Claims

Claims 1. Electrically conductive connecting element (3) for establishing a connection to a first contact part (1), comprising a substantially flat connecting section (6) with a welding surface (7) on which the connecting element (3) can be welded to the first contact part (1) by means of ultrasound, characterized in that at least one welding projection (8) extends from the welding surface (7) in such a way that the welding projection (8) first comes into contact with the first contact part (1) at the start of welding.

2. Connecting element (3) according to claim 1, wherein the connecting element (3) contains a metal, in particular copper, and preferably consists thereof.

3. Connecting element (3) according to one of the preceding claims, wherein the connecting section (6) has a through-opening (22) extending along a longitudinal direction (L) and wherein the welding surface (7) encloses the through-opening (22) in a ring shape.

4. Connecting element (3) according to one of the preceding claims, comprising - a cylindrical section (5) extending in a longitudinal direction (L) from a first end (9) of the connecting element (3) to a second end (10) of the connecting element (3) and - a radially outwardly extending portion (5) from the cylindrical section (5) in the region of the first end (9) flange-shaped section which forms the connecting section (6).

5. Connecting element (3) according to claim 4, wherein the welding projection (8) extends in the direction of the second end (10) in such a way that it first comes into contact with the first contact part (1) at the start of welding.

6. Connecting element (3) according to one of claims 4 and 5, wherein the cylindrical portion (5) at the second end (10) has a pressing surface (17) extending substantially perpendicular to the longitudinal direction (L), on which the connecting element (3) can be pressed against a second contact part (2).

7. Connecting element (3) according to one of the preceding claims, wherein the welding projection (8) has a height (h) along the longitudinal direction (L) which is in the range from 0.1 mm to 0.5 mm, in particular in the range from 0.2 mm to 0.3 mm.

8. Connecting element (3) according to one of the preceding claims, wherein the welding projection (8) has a width (c) in the radial direction which is in the range from 1 mm to 3 mm, in particular in the range from 1.5 mm to 2.5 mm.

9. Connecting element (3) according to one of the preceding claims, wherein the profile of the welding projection (8) has in a sectional plane, in particular in a sectional plane containing the longitudinal direction (L), a radially inner profile section (19) and a radially outer profile section (20), wherein the radially inner profile section (19) and the radially outer profile section (20) are located at a tip (21) at which the welding projection (8) has its maximum height (h).

10. Connecting element (3) according to claim 9, wherein the radially inner profile section (19) of the welding projection (8) has an inner width (a) in the radial direction and the radially outer profile section (20) has an outer width (b) in the radial direction, wherein the ratio of outer width (b) / inner width (a) is in the range from 1:4 to 1:1, more preferably between 1:1.5 to 1:2.5, in particular 1:

2.

11. Connecting element (3) according to one of claims 9 and 10, wherein - the radially inner profile section (19) is straight and extends at an angle (a) to the welding surface (7), which is preferably in the range from 5° to 20°, preferably in the range from 8° to 15°, and / or - the radially outer profile section (20) is straight and runs at an angle (ß) to the welding surface (7), which is preferably in the range from 10° to 30°, preferably in the range from 15° to 25°.

12. Electrical contact arrangement (30) containing - an electrically conductive first contact part (1), - a connecting element (3) according to one of the preceding claims, wherein the welding surface (7) of the connecting element (3) is welded to the first contact part (1) by means of ultrasound.

13. Contact arrangement (30) according to claim 12, wherein the welding projection (8) has penetrated at least partially into the first contact part (1).

14. Contact arrangement (30) according to one of claims 12 and 13, wherein the first contact part (1) contains and preferably consists of an electrically conductive metal such as aluminum, a metallized material, in particular a metallized plastic, or an electrically conductive, in particular metallic, coated material, in particular an electrically conductive coated plastic or an electrically conductive coated ceramic.

15. Contact arrangement (30) according to one of claims 12 to 14, further comprising - a through opening (11) formed in the first contact part (1), - an electrically conductive second contact part (2) with a fixing opening (12), - a mechanical clamping element which penetrates the through-opening (11) of the first contact part (1) and a through-opening (22) of the connecting element (3), in particular the cylindrical section (5) of the connecting element (3), in a longitudinal direction (L) and which is in engagement with the connecting section (6) of the connecting element (3) and the fixing opening (12) in such a way that the connecting section (6), the first contact part (1) and the second contact part (2) are clamped together in the longitudinal direction (L).

16. Contact arrangement (30) according to claim 15, wherein the fixing opening (12) has an internal thread (16), the clamping element as a screw (4) with a head (13) and an external thread (15) Shaft (14) is formed, - the head (13) rests on the connecting section (6), - the shaft (14) penetrates the through-opening (11) of the first contact part (1) and the through-opening (22) of the connecting element (3), in particular a cylindrical section (5) of the connecting element (3), - the external thread (15) is in engagement with the internal thread (16).

17. Contact arrangement (30) according to one of claims 12 to 16, wherein - the connecting element (3) includes a cylindrical portion (5) extending in a longitudinal direction (L) from a first end (9) of the connecting element (3) to a second end (10) of the connecting element (3), - the connecting element (3) further comprises a flange-shaped section extending radially outward from the cylindrical section (5) in the region of the first end (9), which forms the connecting section (6), - the cylindrical section (5) has at the second end (10) a pressing surface (17) extending substantially perpendicular to the longitudinal direction (L), on which the connecting element (3) is pressed against the second contact part (2), the cylindrical section (5) completely penetrates the through opening (11) of the first contact part (1) and - the pressing surface (17) is in electrical contact, in particular in direct electrical contact, with the second contact part (2).

18. Contact arrangement (30) according to one of claims 12 to 17, wherein the welding surface (7) is welded to the first contact part (1) by means of torsional ultrasound.

19. Contact arrangement (30) according to one of claims 12 to 18, wherein the connecting element (3) and / or the second contact part (2) contains and preferably consists of a material different from the material of the first contact part (1), in particular copper.

20. A method for producing a contact arrangement (30) according to one of claims 12 to 19, comprising the steps of a) bringing the welding projection (8) of the welding surface (7) of the connecting element (3) into contact with the first contact part (1), b) introducing ultrasound into the connecting element (3) such that the welding projection (8) at least partially penetrates into the first contact part (1) and at least part of the welding surface (7) is welded to the first contact part (1).

21. Method according to claim 21 for producing a contact arrangement (30) according to one of claims 15 to 19, further comprising the steps c) passing a mechanical clamping element, in particular a shaft (14) of a screw (4), into a longitudinal direction (L) through a through-opening (11) of the first contact part (1), d) mechanically connecting the mechanical clamping element to the fixing opening (12) of the second contact part (2) such that the first contact part (1) and the second contact part (2) are clamped together in the longitudinal direction (L), in particular by screwing an external thread (15) of the shaft (14) into the fixing opening (12) of the second contact part (2).

22. Method according to one of claims 20 and 21, wherein the welding is carried out torsional.

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