DE102018202630A1 - Contact arrangement and method for connecting two conductors - Google Patents

Abstract

The invention relates to a contact arrangement (1) and a method for producing an electrical connection between at least two electrical conductors (3, 5) made of different materials, in particular for connecting at least one electrical line (7, 21) to at least one cell connector (11) battery system. In order to obtain an electrically and mechanically stable connection, it is provided according to the invention that the at least two conductors (3, 5) are interconnected in at least one contact region (13) by a diffusion solder joint (15).

Description

The invention relates to a contact arrangement for producing an electrical connection between at least two electrical conductors made of different materials, in particular for connecting at least one electrical line to at least one cell connector of a battery system. The invention also relates to a method for connecting two conductors made of different materials, in particular for connecting at least one line to at least one cell connector of a battery system. The contact arrangement according to the invention is intended in particular for use in a partially or completely battery electric powered vehicle.

Contact arrangements and methods of making an electrical connection of the above type are known in the art. Frequently, two electrical conductors are electrically and mechanically connected by welding, for example by ultrasonic welding. Although this method of producing the electrical connection is practicable, it has disadvantages. During welding, intermetallic phases usually occur in the contact area. These intermetallic phases can lead to an increase of the electrical resistance in a contact region of the two conductors. In addition, the contact area can be brittle, which in turn can lead to failure of the contact arrangement. This can happen in particular when the contact arrangement is stressed mechanically and / or thermally. Mechanical loads can be, for example, vibrations in a vehicle. Thermal stresses may occur by heating the contact assembly by a heat source, such as a motor or a battery. It is also possible that high currents flowing through the contact assembly generate resistance heat in the contact assembly. The vibrations or the heating, in particular in combination, can lead to breakage of the contact arrangement in the contact area and thereby failure of the connection.

It is therefore the object of the invention to provide a contact arrangement and a method of the type described above, by which at least one of the above-mentioned problems is achieved. In particular, it is an object of the invention to provide a contact arrangement and a method of the type mentioned above, are reliably connected by the two electrical conductors electrically and mechanically.

For the abovementioned contact arrangement, this object is achieved in that the at least two conductors in at least one contact region are connected to one another by a diffusion solder connection. For the method mentioned at the outset, the object according to the invention is achieved in that the two conductors are connected to one another by diffusion soldering, at least in at least one contact region.

The diffusionsgelötete connection of the two conductors of different materials creates a material connection between the conductors. This compound usually does not form such intermetallic phases, which can lead to an increase in brittleness and cause premature failure of the compound. At the same time, the diffusion-soldered connection offers sufficiently high mechanical stability and good electrical conductivity.

In addition, an advantage of the invention is that it is possible to dispense with solder by diffusion soldering. The manufacture of the contact arrangement can be simplified thereby. The invention also has the advantage that it is possible to dispense with additional fluids between the two conductors for the preparation of the compound.

To produce a diffusion solder joint, the at least two conductors are brought into contact with one another and then at least one of the conductors is heated, the temperature in the contact region always remaining below the melting temperature of both conductors. The contact area is the area where the two conductors touch.

The solution according to the invention can be further improved by various configurations which are advantageous in each case and can be combined with one another as desired. These embodiments and the advantages associated with them are discussed below. In this case, a contact arrangement according to the invention can be produced by the method according to the invention.

According to a first advantageous embodiment of a contact arrangement according to the invention, at least one conductor may essentially be formed of copper and at least one conductor may be essentially made of aluminum. As a result, the contact arrangement can be adapted to the different needs of the two conductors. A conductor formed essentially of copper may be advantageous, for example, for transporting high currents. For example, a conductor formed essentially of aluminum can advantageously be used as a cell connector for a battery system.

The at least two conductors are preferably positively connected to each other. This can improve the mechanical stability. At the same time, the non-positive connection a Represent security feature for the contact arrangement. Should it happen in the unlikely event of damage to the diffusion solder joint, the frictional connection can continue to maintain an electrically conductive connection between the two conductors.

In particular, it may be advantageous to make the frictional connection, before the two conductors are diffusion soldered. The frictional connection ensures good contact between the surfaces of the two conductors to form the contact area. This can increase the quality of a diffusion solder joint between the two conductors.

The two conductors can be pressed against each other at least in the later contact area. The pressing of the two conductors together after fabrication of the diffusion solder bond can be maintained to provide failover as described above. Alternatively, it may also be possible to remove means used to press the two conductors together after completion of the diffusion solder bond.

In order to provide both a high mechanical stability and a secure diffusion solder connection of the at least two conductors, the at least two conductors are preferably connected to one another by a gap-free press connection or by a press fit. The at least two conductors can thus be pressed into each other at least in sections.

In order to obtain a particularly good connection of the at least two conductors to one another, preferably at least a section of the one conductor is shrunk onto at least one section of the at least one other conductor. This section then has a shrinkage.

Each of the at least two conductors may comprise at least one cylindrical portion, and the cylindrical portions may be coaxially projecting into one another. This allows a good connection between the two conductors, in particular a good press connection can be achieved.

In particular, the strength of a press fit may be increased by having an outer diameter of the inner cylindrical portion, preferably in an unconnected state, at least equal to an inner diameter of the outer cylindrical portion.

At least one of the conductors may be a stamped and bent part at least in a portion which later forms the contact area. Preferably, the cylindrical portions are monolithically molded to the at least one conductor.

Alternatively, at least one conductor may also be connected to a separate cylindrical section. This cylindrical portion is then preferably formed of a substantially same material as the remaining conductor.

Preferably, at least one outer cylindrical portion is formed substantially of copper and at least one inner cylindrical portion is formed substantially of aluminum. For producing the connection or for pressing the two sections into one another, at least the outer, preferably substantially copper, cylindrical section can be heated. This allows it to expand at least in sections, so that its inner diameter is temporarily increased. As a result, the joining of the cylindrical sections can be facilitated. The heat introduced into the conductors consisting essentially of copper can also be used to produce the diffusion solder connection.

At least one of the conductors may be a bus bar or a tap of a ribbon cable. The at least one other conductor may be a cell connector and / or a Stromableitschiene a battery system. This represents an independent aspect of the invention. As already described above, the advantages of the contact arrangement according to the invention in such an embodiment are particularly significant. Battery systems, especially those for battery electric vehicles, are usually exposed to high mechanical and thermal loads. They can therefore profit particularly from the advantages of the contact arrangement according to the invention.

The busbar or the tap of a ribbon cable is preferably formed essentially of copper. The cell connector or the Stromableitschiene is preferably formed substantially of aluminum. "Essentially" refers to alloys which predominantly contain the named material. So this does not exclude that these elements additionally contain other materials.

At least one of the conductors may be heated before and / or during the pressing. The heating prior to pressing, on the one hand, can be helpful, as described above, for pressing the two conductors into one another. On the other hand, the heat introduced before pressing can also already be used for producing the diffusion solder joint. This can be dispensed with a subsequent heating.

Alternatively or in addition to heating at least one of the conductors before and / or after pressing, at least one of the conductors may be heated after pressing to produce or improve the diffusion solder joint. This can be done, for example, if there is no pressing of the conductors into one another.

But even when pressing two conductors into each other, for example, those with cylindrical sections, the subsequent heating can be used alternatively or additionally.

It may also be part of the process that cylindrical sections are formed on the at least two conductors. This is preferably done before a pressing process in which the two sections are pressed into each other.

Alternatively, however, it is also possible that the cylindrical portions are formed after pressing. For example, planar sections of the at least two conductors can be pressed against each other. Subsequently, it is possible to produce the diffusion solder joint. Thereafter, the interconnected planar areas can be shaped, for example by rolling, so that cylindrical sections are made. Preferably, however, the cylindrical sections are formed prior to pressing and prior to making the diffusion solder bond.

When pressing against one another, an outer section of a conductor is preferably heated. This may already be enough to produce the diffusion solder joint. Likewise, the heating of the outer conductor may be sufficient to facilitate the pressing together of the two conductors, in particular by an extension of the outer conductor. Preferably, the heating takes place before and / or during the pressing. Subsequent heating of the outer conductor may be useful to ensure that a sufficiently good diffusion solder joint is produced. "Sufficiently good" means a sufficiently high conductivity for the respective application and a sufficiently high mechanical stability.

If the outer conductor or a portion thereof is heated so that it expands, the contraction of the conductor during cooling can lead to a shrinkage on the inner conductor.

Various methods can be used to generate heat in at least one of the at least two conductors. For example, at least one of the conductors can be arranged at least in sections in a heating device in order to generate the necessary heat. Such a heater may be an oven. Alternatively, a burner, for example a gas burner, a laser or an electric heating element can be used to generate the heat.

Preferably, however, the heat is generated by induction in at least one of the conductors. For this purpose, at least one conductor can be introduced into the vicinity or into the interior of a coil with at least one section, through which a high-frequency alternating current flows. This procedure is quick and easy to perform. In addition, the introduced heat is easily adjustable based on the electrical parameters in the coil, ie voltage, current and frequency.

The invention is explained in more detail below by way of example with reference to advantageous embodiments with reference to the drawings. The feature combination exemplified in the embodiments can be supplemented according to the above statements accordingly for a particular application by further features. Also, also in accordance with the above statements, individual features may be omitted in the described embodiments, if the effect of this feature in a specific application does not matter.

In the drawings, the same reference numerals are always used for elements of the same function and / or same structure.

• 1 eine schematische Seitenansicht einer ersten Ausführungsform einer erfindungsgemäßen Kontaktanordnung; und
• 2 eine schematische Darstellung einer zweiten vorteilhaften Ausführungsform in einer perspektivischen Ansicht (unten) und einer geschnittenen Ansicht (oben).

Show it:

• 1 a schematic side view of a first embodiment of a contact arrangement according to the invention; and
• 2 a schematic representation of a second advantageous embodiment in a perspective view (below) and a sectional view (top).

First, the construction of a first advantageous embodiment of a contact arrangement according to the invention 1 based on 1 described. Subsequently, the preparation of such a contact arrangement 1 , in particular by means of the method according to the invention, received.

The contact arrangement 1 is made of two electrical conductors 3 and 5 educated. These are made of different materials. Preferably, one of the conductors consists essentially of copper and the other conductor consists essentially of aluminum. The leader 3 is merely exemplary as a ribbon cable 7 educated leadership 7 with a tap located on it 9 shown.

The leader 3 may alternatively only as a section of the tap 9 or as a ribbon cable 7 without tap 9 be formed. The tap 9 For example, an end portion of the ribbon cable 7 be in which the cable is compressed. Alternatively, the tap 9 also be a plate with the ribbon cable 7 connected is. The tapping is preferred 9 a sleeve in which an end portion of the ribbon cable 7 is arranged.

The at least one other conductor, in the embodiment of the ladder shown by way of example 5 , is preferably formed essentially of aluminum. The conductor is preferred 5 a cell connector 11 a battery system, in particular for an electric vehicle.

In a contact area 13 who in 1 dashed lines, the two leaders touch each other 3 and 5 , In this contact area 13 are the two leaders 3 and 5 by a diffusion solder joint 15 connected with each other. In particular, the two leaders 3 and 5 through the diffusion solder joint 15 electrically and mechanically interconnected.

The connection of the two conductors 3 and 5 through the diffusion solder joint 15 has the advantage over a welded joint that no such intermetallic phases occur that cause at least one of the conductors 3 or 5 in the contact area 13 or becomes brittle in adjacent areas. This brittleness can lead to failure of the connection, for example, in vibration or thermal stress. Intermetallic phases can arise because of the two conductors 3 and 5 at least in the contact area 13 be heated above their respective melting temperature and the liquid metals flow into each other at least partially.

In a Diffusionslötverbindung although an exchange of material takes place. However, areas where material is exchanged are much smaller. This is due to the fact that the materials are not heated above their melting temperature and therefore a confluence can not take place.

For producing the contact arrangement according to the invention 1 become the leaders 3 and 5 pressed together. The directions in which the two conductors 3 and 5 are pressed together by the arrows 17 and 19 characterized. For pressing, for example, one of the conductors can be fixed on a holder and the other conductor can be pressed by means of a pressing tool against the fixed conductor.

Before and / or after pressing at least one of the two conductors 3 or 5 so far heated that a diffusion process between the conductors 3 and 5 can take place. Both conductors remain below their melting temperature. If only one of the conductors is heated, the heat of this conductor can be transferred to the other conductor by contact transfer. Alternatively, both leaders can 3 and 5 heated at the same time. For heating, common methods and apparatuses for heat generation can be used. Preferably, however, the heat generation is used by induction, since this can be comparatively well steuem.

Below is a second advantageous embodiment of the contact arrangement according to the invention 1 with reference to the 2 described. In this case, the embodiment is in 2 above in a cross section and in 2 shown below in a perspective view.

For the sake of brevity, below is just the differences to those with respect to the 1 described embodiment received.

The leader 3 The second embodiment is preferably part of a busbar 21 which can be a conduit. Alternatively, the leader 3 also be designed for connection to a separate busbar (not shown) or another electrical line.

The conductor is preferred 3 as in the first embodiment, formed essentially of copper. The leader 5 is preferably a section of a cell connector 11 or a Stromableitblechs and formed substantially of aluminum. Both conductors are preferred 3 and 5 formed as stamped and bent parts.

The leader 3 can with an opening 23 be provided. The opening 23 can be used to connect the conductor 3 serve with another electrically conductive element. Likewise, the opening 23 serve the conductor 3 mechanically fix. Overall, the leader 3 essentially in the form of a cable lug. The opening 23 can be provided with an internal thread for a screw connection.

The leader 3 has a cylindrical section 25 on, its interior from an axial end 27 is accessible. The cylindrical section is preferred 25 in a circumferential direction 29 completely closed. The cylindrical section 25 can therefore train a pipe. However, this is not mandatory.

The leader 5 also has a cylindrical section 31 on. The cylindrical section 31 can form a closed tube. That is, the cylindrical section 31 of the leader 5 can also along a circumferential direction 33 be completely closed. Again, this is not mandatory. That is, the cylindrical section 31 may also have interruptions.

The rest of the ladder 5 (indicated only by dashed lines) may have a shape which is of a continuation of in 2 deviates shown cable lug-like shape. The cylindrical section 31 can be to one from the rest of the ladder 5 or from the cell connector 11 be protruding portion formed.

Alternatively, the leader 5 formed in the form of a cable lug and then connected to a separate cell connector. As the leader 5 and the cell connector 11 Having a substantially same material composition, a connection can be easily made by welding or other cohesive connections here.

An outer diameter 35 in the cylindrical section 31 of the leader 5 is, in particular in a non-connected state, preferably at least as large as an inner diameter 37 of the cylindrical section 25 of the leader 3 , The cylindrical section 31 of the leader 5 protrudes into the cylindrical section 25 of the leader 3 into it.

The section is preferred 31 non-positively in the section 25 held. This can be done by the above sizing the diameter 35 and 37 be achieved. To join the ladder 3 and 5 So they have to be pressed together. Preferably, the two conductors 3 and 5 by a gap-free press connection, so a press fit, connected together. The cylindrical sections 25 and 31 coaxially coexist.

To join the sections 25 and 31 can the leader 3 along the direction 17 against the leader 5 and / or the leader 5 along the direction 19 against the leader 3 be pressed.

The contact area 13 between the ladders 3 and 5 is formed where the outside 39 of the cylindrical section 31 on the inside 41 of the cylindrical section 25 is applied. The contact region thus extends along the circumferential directions 29 or. 33 , At the same time, the contact area extends 13 along a common axial direction 43 along the cylindrical sections 25 and 31 are arranged coaxially with each other. The conductors are preferred 3 and 5 along the entire contact area 13 connected by a diffusion solder joint.

For diffusion soldering, various methods can be used. The conductor is preferred 3 , which consists essentially of copper, prior to pressing the cylindrical sections 25 and 31 with each other, warmed up. This allows the diameter in the cylindrical section 25 increase.

During or after heating, the cylindrical sections become 25 and 31 pressed into each other. The heat creates the diffusion solder bond. It should be noted that even after the pressing of the two conductors 3 and 5 at least one of the leaders 3 or 5 can be further heated to the quality of the diffusion solder joint 15 sure.

When cooling the conductor 3 , in particular of the cylindrical portion 25 , its inside diameter can be 37 decrease again, leaving the cylindrical section 25 on the cylindrical section 31 has shrunk. The cylindrical section 25 thus forms a shrinkage 45 on the cylindrical section 31 ,

The heat to increase the diameter 37 of the section 25 and for generating the diffusion solder joint 15 is preferably generated by induction. At least the conductor can do this 3 be brought into the vicinity of a coil or in the interior of a coil. When applying a high-frequency alternating voltage then an induction current in the conductor 3 are generated, which in turn leads to the generation of induction heat.

LIST OF REFERENCE NUMBERS

1

Contact configuration

3

ladder

5

ladder

7

Ribbon cable

9

tap

11

cell connectors

13

contact area

15

diffusion soldering

17

arrow

19

arrow

21

conductor rail

23

opening

25

Cylindrical section of a ladder

27

Axial end

29

Circumferential direction of a conductor

31

Cylindrical section of another ladder

33

Circumferential direction of the other conductor

35

Outer diameter of the inner cylindrical section

37

Inner diameter of the outer cylindrical portion

39

Outside of the inner cylindrical section

41

Inside of the outer cylindrical section

43

Common axial direction

45

shrinking

Claims (15)

Contact arrangement (1) for producing an electrical connection between at least two electrical conductors (3, 5) made of different materials, in particular for connecting at least one electrical line (7, 21) to at least one cell connector (11) of a battery system, characterized in that at least two conductors (3, 5) in at least one contact region (13) by a diffusion solder joint (15) are interconnected. Contact arrangement (1) after Claim 1 , characterized in that at least one conductor (3) consists essentially of copper and at least one conductor (5) is formed substantially of aluminum. Contact arrangement (1) after Claim 1 or 2 , characterized in that the at least two conductors (3, 5) are non-positively connected to each other. Contact arrangement (1) after Claim 3 , characterized in that the at least two conductors (3, 5) are interconnected by a gap-free press connection. Contact arrangement (1) according to one of Claims 1 to 4 , characterized in that each of the at least two conductors (3, 5) has at least one cylindrical portion (25, 31) and the cylindrical portions (25, 31) project coaxially into one another. Contact arrangement (1) after Claim 5 characterized in that at least one outer cylindrical portion (25) substantially of copper and at least one inner cylindrical portion (31) is formed substantially of aluminum. Contact arrangement (1) according to one of Claims 1 to 6 , characterized in that at least one of the conductors (3) is a busbar or a tap (9) of a ribbon cable (7), and at least one conductor (5) is a cell connector (11) and / or a Stromableitschiene a battery system. Method for connecting two conductors (3, 5) made of different materials, in particular for connecting at least one line (7, 21) to at least one cell connector (11) of a battery system, characterized in that the two conductors (3, 5) at least in at least a contact region (13) are joined together by diffusion soldering. Method according to Claim 8 , characterized in that the two conductors (3, 5) are pressed against each other at least in at least one contact region (13) and at least one of the conductors (3, 5) is heated. Method according to Claim 9 , characterized in that at least one of the conductors (3, 5) is heated before and / or during pressing. Method according to one of Claims 8 to 10 , characterized in that the at least two conductors (3, 5) are pressed into each other at least in sections. Method according to one of Claims 8 to 11 , characterized in that on the at least two conductors (3, 4) cylindrical portions (25, 35) are formed. Method according to Claim 12 characterized in that the cylindrical portions (25, 31) are formed such that a cylindrical portion (31) of the at least one conductor (5) has an outer diameter (35) at least an inner diameter (37) of a cylindrical portion (25 ) of the at least one other conductor (3). Method according to one of Claims 11 to 13 , characterized in that a section (25) of a conductor (3) which lies on the outside when being pressed into one another is heated. Method according to one of Claims 8 to 14 , characterized in that at least one of the conductors (3, 5) is inductively heated.

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