EP2362491B1 - Method for connecting an electrical conduit with an electrical connection element - Google Patents

Description

The invention relates to a method for connecting an electrical line to an electrical connection element.

Electrical lines, in particular those used in vehicles for power supply or for the transmission of electrical control signals, are conventionally formed of copper material and connected to electrical connection elements made of copper material, which facilitate the connection of the electrical lines to vehicle components.

Because of the higher weight electrical conductivity of aluminum compared to copper, it is desirable to use an aluminum electrical conduit instead of a copper conduit.

However, in the use of such an aluminum electrical wire, there is a problem that, with conventional joining methods, no connection between the electric wire and an electric terminal can be made of a metal material other than the electric wire material, such as copper, which is durable both mechanically stable and sufficiently electrically conductive.

This problem is due to the fact that aluminum forms on its surface an electrically relatively well insulating oxide layer, when exposed to the ambient air. Such an oxide layer increases the electrical resistance between the electrical line and the electrical connection element. On the other hand, aluminum has a significantly higher coefficient of thermal expansion than, for example, copper, and therefore, after repeated heating and cooling, a loosening of the connection between the electrical line and the connection element can occur, as a result of which both the mechanical stability and the electrical conductivity of the connection with time decreases. In addition, aluminum is in principle softer than, for example, copper, which is why it is difficult to produce a compound which has sufficient tensile strength. In particular, aluminum may deform by flow when subjected to tensile loading, thereby contributing to impairing the stability of the joint.

DE 199 02 405 A1 discloses a method having the features of the preamble of claim 1.

DE 198 21 630 C1 discloses a connector for an electrical conductor which is frictionally connected thereto by compression or crimping, wherein the connector and the conductor have different metal materials and the connector is provided on its inside with slots or beads.

JP 2009 259532 A discloses a crimp termination for an aluminum conductor which has a notch and slots on its inside facing the aluminum conductor.

The invention has for its object to provide a method with which a permanently mechanically stable and electrically conductive connection between an electrical line with at least one aluminum wire and a terminal made of a metal material other than the material of the aluminum wire.

To solve this problem, a method having the features of claim 1 is provided.

The method of claim 1 is for connecting an electrical line to an electrical connection element, wherein the electrical line has at least one aluminum wire and the connection element is formed from a different metal material from the material of the aluminum wire. The method comprises crimping a crimping section of the connecting element with the at least one aluminum wire, and additionally welding it to the at least one
an aluminum wire crimped crimping portion of the connecting element with the at least one aluminum wire by means of resistance welding.

The inventive method thus combines two connection processes, namely the crimping of the crimping section with the at least one aluminum wire on the one hand and the subsequent resistance welding on the other hand. This combination ensures a permanently mechanically stable and electrically conductive connection between the electrical line and the connecting element.

By squeezing the at least one aluminum wire and the crimping portion against each other during crimping, a mechanical connection is first made between the at least one aluminum wire and the crimping portion, which has preliminarily sufficient mechanical stability and electrical conductivity. In this case, an existing on the at least one aluminum conductor oxide layer is already at least partially broken and reaches a certain electrical conductivity between the aluminum line and the connection element by crimping.

If the electrical line has a plurality of aluminum wires, not only the individual aluminum wires are crimped with the connection element during crimping, but the aluminum wires are also squeezed together, resulting in an improved conductivity also between the individual aluminum wires.

An optimal mechanical stability and electrical conductivity of the compound is finally achieved according to the invention in that after crimping with the at least one aluminum wire crimped crimping section is additionally welded to the at least one aluminum wire, that is, so a cohesive connection between them is created. In this case, so much electrical energy is supplied to the crimping area that the at least one aluminum wire and the connection element are melted in their contact area and existing oxide layers are at least approximately completely broken, thereby further reducing the contact resistance between the connection element and the at least one aluminum wire.

A particular advantage of the method according to the invention consists in the fact that the crimping force exerted during the crimping on the crimping section and the at least one aluminum wire can be lower due to the additional welding than in the case of conventional crimping connections in which no welding takes place.

In addition, when using an electrical lead with multiple aluminum wires, the oxide layers of the individual wires are broken and the wires are at least partially fused together so that there are also reduced contact resistances and better electrical conductivity between the wires.

In this way, by the combination of crimping and resistance welding according to the invention, a permanently electrically conductive and mechanically stable connection can be produced between an aluminum line and a connection element, which is formed from a metal material that differs from the material of the aluminum line. Different materials can also be different aluminum alloys.

Advantageous embodiments of the method according to the invention are described in the subclaims, the description and the drawings.

According to one embodiment, at least two electrodes are brought into contact with the connection element during resistance welding, and a current flow is generated between the electrodes via the connection element and the at least one aluminum wire. In this case, it is preferable not to bring the electrodes directly into contact with the at least one aluminum wire during resistance welding. In this way, undesirable interactions between the at least one aluminum wire and the electrodes can be prevented. Suitable electrodes may, for example, comprise a tungsten material.

During resistance welding, the connection element can be clamped between the electrodes. As a result, a good mechanical stability of the overall arrangement is achieved during the resistance welding.

During resistance welding, a clamping force can also be exerted on the connection element by the electrodes, which is of the same order of magnitude as a force exerted on the connection element during crimping. In this way, during the resistance welding an additional compression of the connection element with the at least one aluminum wire, which leads to an even better connection between the two.

In order to keep the connecting element and the at least one aluminum wire during the resistance welding even safer, the Connection element are additionally clamped during resistance welding between two electrically insulating retaining elements. Because the holding elements are designed to be electrically insulating, a short circuit between the electrodes via the holding elements is avoided. Particularly suitable are holding elements which comprise a ceramic material, since they have a particularly high mechanical stability with a high electrical insulation effect.

Preferably, crimping forms an F-crimp connection or a hexagonal crimp connection.

In the production of an F-crimp connection, the crimping section has two free crimping tabs, which form a receptacle into which the at least one aluminum wire is inserted, wherein the crimping tabs are crimped onto the aluminum wire during crimping, which is usually in and for both crimping tabs the same pressing process takes place. The two Crimpflügel can thereby be connected by a base portion of the crimping portion and be formed so that the crimping portion assumes a substantially U- or V-shaped cross section before crimping. During crimping, the crimped blades can be bent so that the free ends of the crimping blades point in the direction of the at least one aluminum wire and are pressed against the aluminum wire.

In the manufacture of a hexagonal crimp, also called hex crimp, an end portion of the at least one aluminum wire is inserted into a closed crimp barrel of the crimp portion and the crimp barrel is at least partially compressed so that it assumes a substantially hexagonal cross-section. As a result, a particularly robust crimp connection is achieved. A hexagonal Crimped connection can be produced, for example, using a crimping tool with hexagonal internal cross section.

The use of a crimp section with a closed crimp barrel also proves to be advantageous because it ensures in a simple manner during subsequent resistance welding that the electrodes placed on the crimp section do not come into direct contact with the at least one aluminum wire.

In addition, the crimp sleeve of a hexagonal crimp connection has two substantially parallel and flat outer surfaces on which the electrodes used for the resistance welding step can be applied in a particularly simple and large-area manner.

According to the invention, the crimping section of the connecting element is provided with indentations on its inner side facing the electrical line and, when crimped, material of the at least one aluminum wire is forced into the recesses. As a result, the mechanical strength and electrical conductivity of the compound produced are further improved and thus ultimately increases the reliability and life of the compound even further.

Preferably, the recesses are formed so that they are only partially filled during crimping by the material of the at least one aluminum wire.

The depressions are similar to a greater extent of the at least one aluminum wire due to the different thermal expansion coefficients of aluminum and copper compared to The connection element when heated and can therefore be referred to as compensation wells. The material of the aluminum wire, when heated, may expand into the areas of the recesses left free after crimping, without the copper material being forced outward by the expanding aluminum. Conversely, a sufficient mechanical and electrical contact with the connection element is ensured even with a cooling of the aluminum and a corresponding contraction, since the aluminum is always at least partially in contact with the lying between adjacent recesses protrusions of the connection element.

As a result, the depressions thus contribute to avoiding a loosening of the connection due to temperature fluctuations, in particular due to repeated heating and cooling of the connection element and the electrical line, and to ensure a permanently reliable mechanical and electrical connection.

According to an advantageous development, the depressions in the crimping section are formed by a cutting, milling, pressing or knurling process. In other words, the recesses are created by having material of the crimping section, i. Material of the connection element itself, is removed or displaced. Protrusions lying between adjacent recesses may, for example, have a substantially pyramidal or truncated pyramidal shape.

In order to prevent an aluminum wire from being completely received in a depression, the maximum widths of the depressions are chosen smaller than the diameter of an aluminum wire.

According to another embodiment, the crimping portion of the terminal member comprises a plating of a metal-containing material having at least one metal other than aluminum and copper. It is also conceivable that the cladding contains neither aluminum nor copper. The cladding is advantageously arranged so that when the connection is made, the metal-containing material of the cladding abuts against the at least one aluminum wire, so that in the region of the transition between the connection element and the aluminum line, the metal-containing cladding material directly adjoins the at least one aluminum wire borders. By a suitable choice of the metal-containing material, the properties of the compound can be optimized. The plating may, for example, comprise a tin material, since tin is suitable for achieving particularly low contact resistances to aluminum.

According to yet another embodiment, after crimping, the crimping portion of the terminal member is provided with a seal sealing the crimping portion. The seal may be designed such that it seals the crimp section airtight and / or watertight against the surroundings of the crimp section. Such a seal prevents corrosion of the boundary between the terminal and the electric wire, thus contributing to the long-term reliability of the manufactured joint.

The seal may be formed of a plastic-containing material and include, for example, a urethane-based thermoplastic elastomer, a polyamide, a polyvinyl chloride, a polyurethane, or a butyl rubber material. Preferably, the seal encloses both the crimping portion of the terminal member and an end portion of an insulation sheath of the electric wire.

The seal may be applied to the crimping section by an injection molding process, a casting process, or a foaming process. Alternatively, the seal can also be applied by a shrink tube is pushed onto the line and the connection element and shrunk while supplying heat to the connection element and the line. Use in the invention finds an electrical connection element made of metal material, which comprises a crimp section, which is formed for producing a crimp connection with an electrical line with at least one aluminum wire, which is formed of a different material of the aluminum wire material and which at its electrical Conduction-facing inner side is provided with a plurality of recesses, in which material of the at least one aluminum wire can expand during crimping. The connecting element according to the invention enables a permanently reliable connection to an electrical line made of aluminum, so that the advantages explained above can be achieved accordingly.

Fig. 1

eine perspektivische Ansicht eines Crimpabschnitts eines elektrischen Anschlusselements;

Fig. 2

eine Querschnittsansicht des mit einer elektrischen Leitung vercrimpten Crimpabschnitts von Fig. 1 während eines Widerstandsschweißvorgangs;

Fig. 3

eine perspektivische Ansicht des Anschlusselements und der elektrischen Leitung von Fig. 1 nach ihrer Crimp- und Schweißverbindung;

Fig. 4

eine perspektivische Ansicht eines ersten alternativen Anschlusselements und einer elektrischen Leitung nach ihrer Crimp- und Schweißverbindung;

Fig. 5

eine Querschnittsansicht des mit der elektrischen Leitung vercrimpten Anschlusselements von Fig. 4 während eines Widerstandsschweißvorgangs;

Fig. 6a

eine Querschnittsansicht eines Ausschnitts eines Crimpabschnitts eines zweiten alternativen Anschlusselements;

Fig. 6b

die Querschnittsansicht von Fig. 6a nach dem Vercrimpen des Crimpabschnitts mit einer elektrischen Leitung;

Fig. 6c

die Querschnittsansicht von Fig. 6b nach einer Erwärmung von Anschlusselement und elektrischer Leitung; und

Fig. 6d

die Querschnittsansicht von Fig. 6c nach einer auf die Erwärmung folgenden Abkühlung von Anschlusselement und elektrischer Leitung.

Hereinafter, the present invention will be described purely by way of example with reference to an advantageous embodiment with reference to the accompanying drawings. Show it:

Fig. 1

a perspective view of a crimping portion of an electrical connection element;

Fig. 2

a cross-sectional view of crimped with an electrical line crimping of Fig. 1 during a resistance welding process;

Fig. 3

a perspective view of the connection element and the electrical line of Fig. 1 after its crimping and welding connection;

Fig. 4

a perspective view of a first alternative connection element and an electrical line after its crimping and welding connection;

Fig. 5

a cross-sectional view of the crimped with the electrical line connection element of Fig. 4 during a resistance welding process;

Fig. 6a

a cross-sectional view of a section of a crimping portion of a second alternative connection element;

Fig. 6b

the cross-sectional view of Fig. 6a after crimping the crimping portion with an electric wire;

Fig. 6c

the cross-sectional view of Fig. 6b after heating of connection element and electrical line; and

Fig. 6d

the cross-sectional view of Fig. 6c after a subsequent heating to the cooling of the connection element and electrical line.

Fig. 1 shows a perspective view of a crimping section 12 of an electrical connection element 10, which is punched out of a metal sheet - in the present embodiment, a copper sheet. The crimp section 12 serves to connect the connection element 10 to an electrical line 20 (FIG. FIGS. 2 and 3 ) and includes two crimp blades 14 that are bent over in a pre-assembled state so that the crimping portion 12 has a substantially U-shaped cross-section.

In addition to the crimp wings 14, the crimping section 10 comprises two crimping tongues 18, which serve for crimping the connection element 10 with an insulation jacket 24 of the electrical line 20.

On the crimping tongues 18 opposite side of the Crimpflügel 14, a contact portion 21 closes ( Fig. 3 ) of the connecting element 10 to the crimping section 12, which may be formed in a socket or plug-shaped and used to connect the connecting element 10 with a contact element such as an electrical device.

With reference to Fig. 2 and Fig. 3 the connection of the connection element 10 to the electrical line 20 will be explained in more detail below.

The electrical line 20 has a plurality of aluminum wires combined into an aluminum wire bundle 22, wherein the aluminum wires of the bundle 22 are not shown individually for the sake of clarity are. Alternatively, the electrical lead 20 may include only one aluminum wire.

The electrical line 20 is stripped in an end region by removing an insulating jacket 24 surrounding the aluminum wires 22, wherein the length of the stripped region is preferably selected to be slightly longer than the length of the crimping prong 14 seen in the longitudinal direction of the connecting element 10. Subsequently, the electrical line 10 is inserted into the crimp section 12 such that the stripped aluminum wires 22 lie between the crimp wings 14.

In order to provide a strain relief of the connection between line 20 and connection element 10, an end region of the remaining insulation jacket 24 is crimped with the crimping tongues 18 provided for this, as shown in FIG Fig. 3 is shown.

In addition, the crimp blades 14 and the aluminum wires 22 are crimped together by bending the crimps 14 toward each other and pressing them on the aluminum wires 22 exposed between the crimped blades 14. Preferably, the crimping takes place using a suitably adapted crimping tool or a similar tool. After crimping, the aluminum wire bundle 22, viewed in the longitudinal direction, is completely surrounded, at least in sections, by material of the crimping section 12.

After crimping, the aluminum wires 22 and the crimping portion 12 are welded together by resistance welding. In order to prevent an interim loosening of the crimp connection due to temperature fluctuations, the welding is preferably carried out as soon as possible after crimping. To limit unwanted Temperature fluctuations between the crimping and the welding can also be monitored or at least approximately kept constant a temperature of the line 20, the connection element 10 or the ambient air.

Fig. 2 FIG. 12 shows a cross-sectional view of the crimping portion 12 of the terminal 10 crimped with the electric wire 10 during resistance welding.

During resistance welding, two electrodes 26, which may be formed, for example, of a tungsten material, are brought into abutment on an upper or lower side of the crimping section 12. The electrodes 26 each exert a predetermined force on the crimp section 12, which is directed in the direction of the respective other electrode 26, so that the connection element 10 is clamped between the electrodes 26. The clamping forces can be selected so that they cause additional crimping of the crimping section 12 and the aluminum wires 22.

In order to ensure correct positioning of the crimping portion 12 between the electrodes 26 during resistance welding, in addition, two holding members 28 are abutted laterally on the crimping portion 12, pinching the crimping portion 12 and moving the crimping portion 12 in a direction perpendicular to the direction prevent the clamping forces exerted by the electrodes 26. The holding elements may be formed from an electrically insulating ceramic material.

Fig. 3 shows the completed arrangement of connection element 10 and electrical line 20 after crimping and welding.

Fig. 4 shows a perspective view of an arrangement of a first alternative electrical connection element 10 and an electrical line 20 after establishing a connection by crimping and then resistance welding a crimping section 12 of the connection element 10 with aluminum wires of the electrical line 20. Fig. 5 shows the arrangement of Fig. 4 during a resistance welding process.

The electrical line 20 corresponds to the electrical line of Fig. 1 to 3 ,

The electrical connection element 10 differs from the in Fig. 1 to 3 shown connecting element, that its crimp section 12 is formed by a crimp sleeve 30. In the pre-assembly state of the connection element 10, not shown, the crimp sleeve 30 has a substantially round cross-section. To make the connection, the stripped aluminum wires 22 (FIG. Fig. 5 ) of the electric wire 20 is inserted into the crimping barrel 30 and the crimping barrel 30 is crimped by hexagonal crimping with the aluminum wires 22, thereby deforming into a mold having a substantially hexagonal cross section. This results in three pairs of opposing outer surfaces 31 of the crimp sleeve 30, which are substantially planar and substantially parallel and thus particularly well for the application of the electrodes 26 (FIGS. Fig. 5 ) during the subsequent resistance welding of the crimp section 12 to the aluminum wires 22.

Fig. 6a-d show a cross-sectional view of a section of a crimp section 12 of a connection element 10 according to the invention. This connection element 10 may be a connection element 10 of FIG Fig. 1 to 3 or a connection element 10 of 4 and 5 act with the difference that the crimping portion 12 of the connecting element 10 is provided on its the electrical line 20 facing inside 36 with a plurality of recesses 32. The depressions 32 can be produced, for example, by a cutting, milling, pressing or knurling process.

The maximum width d of the recesses 32 is less than the diameter of an aluminum wire 40 (FIG. Fig. 6b-d ) of the electric wire 20.

Between adjacent depressions 32 are projections 34 of the crimping section 12, which have a substantially pyramidal or truncated pyramidal shape.

Fig. 6b shows the section of Fig. 6a After the crimping portion 12 of the terminal 10 has been crimped with the aluminum wire 40. As shown, the material of the aluminum wire 40 is partially forced into the recess 32.

Fig. 6c shows the section of Fig. 6a and Fig. 6b after heating of connection element 10 and aluminum wire 40. By the heating, the aluminum wire 40 expands so that the recess 32 is at least approximately completely filled by the aluminum material of the wire 40. The fact that the aluminum material in this case in the in Fig. 6b shown free area 42 of the recess 32 can expand, pressure on the connecting element 40 and a possible resulting bending and loosening of the crimp connection is prevented.

Fig. 6d shows the section of Fig. 6a-c after cooling following the heating of connection element 10 and aluminum wire 40. The cooling is formed in the recess 32 again a free area 42, in which the aluminum wire 40 can expand at a renewed heating.

As in Fig. 6b-d At the same time, any loosening of the crimp connection due to repeated heating and cooling by the recesses 32 is effectively avoided. In this way, a good mechanical and electrical contact between the connection element 10 and the electrical line 20 is permanently ensured.

LIST OF REFERENCE NUMBERS

10

connecting element

12

crimp

14

Crimpflügel

18

Crimpzunge

20

electrical line

21

Contact section

22

Aluminum wire bundle

24

insulation jacket

26

electrode

28

retaining element

30

crimp barrel

31

outer surface

32

deepening

d

distance

34

head Start

36

inside

40

aluminum wire

42

free area

Claims (9)

1. A method for connecting an electrical line (20) to an electrical connection element (10), wherein the electrical line (20) comprises at least one aluminum wire (22; 40), and the connection element (10) is formed of a metal material different from the material of the aluminum wire, comprising the steps:

   crimping a crimping section (12) of the connection element (10) with the at least one aluminum wire (22; 40); and

   welding the crimping section (12) crimped with the at least one aluminum wire (22; 40) to the at least one aluminum wire (22; 40) using resistance welding, characterized in that

   the at least one aluminum wire (20; 40) consists of aluminum or an aluminum alloy, in that the crimping section (12) of the connection element (10) is provided with recesses (32) on its inner side (36) facing the electrical line (20), and in that during crimping, material of the at least one aluminum wire (22; 40) is pressed into the recesses (32), the maximum width (d) of the recesses (32) being less than the diameter of an aluminum wire (22; 40).
2. Method according to claim 1,
   characterized in that
   at least two electrodes (26) are brought into abutment against the connection element (10) during resistance welding, and a current flow is produced between the electrodes (26) via the connection element (10) and the at least one aluminum wire (22; 40).
3. Method according to claim 2,
   characterized in that
   the electrodes (26) are not brought into direct contact with the at least one aluminum wire (22; 40) during resistance welding.
4. Method according to claim 2 or 3,
   characterized in that
   the connection element (10) is clamped between the electrodes (26) during resistance welding.
5. Method according to at least one of the preceding claims,
   characterized in that
   the connection element (10) is clamped between two electrically insulating holding elements (28) during resistance welding, the holding elements (28) comprising in particular a ceramic material.
6. Method according to at least one of the preceding claims,
   characterized in that
   a F-crimped connection or a hexagonal crimped connection is formed by the crimping.
7. Method according to at least one of the preceding claims,
   characterized in that
   the recesses (32) in the crimping section (12) are formed by removing or displacing material of the crimping section (12) and in particular by cutting, milling, pressing or knurling.
8. Method according to at least one of the preceding claims,
   characterized in that
   the crimping section (12) of the connection element (10) has a plating of a metal-containing material, in particular of a tin-containing material.
9. Method according to at least one of the preceding claims,
   characterized in that
   the crimping section (12) of the connection element (10) is provided, after crimping, with a seal sealing the crimping section (12).

Images