DE102012025004A1 - Joint connection between pole terminal of electrical storage cell and pole connector, useful in memory cell pack, where terminal and connector are cohesively connected with each other by laser using laser source with double-focus technique - Google Patents

Abstract

The joint connection between a pole terminal of an electrical storage cell and a pole connector (7), is claimed. The pole terminal and the pole connector are cohesively connected with each other by laser using a laser source having multi-focus technique such as a double-focus technique. The double-focus technique is present in a direction of parallel or tandem focal points of the laser beams. The connection between the pole terminal and pole connector is formed as a linear I-weld seam (16), which has a depth corresponding to 91% of a thickness of the pole terminal and pole connector. The joint connection between a pole terminal of an electrical storage cell and a pole connector (7), is claimed. The pole terminal and the pole connector are cohesively connected with each other by laser using a laser source having multi-focus technique such as a double-focus technique. The double-focus technique is present in a direction of parallel or tandem focal points of the laser beams. The connection between the pole terminal and pole connector is formed as a linear I-weld seam (16), which has a depth corresponding to 91% of a thickness of the pole terminal and pole connector. The weld seam has a connection area of 5-20 mm 2> per 100 Å to achieve the connection. The pole terminal and the pole connector have a plate-shape. Independent claims are included for: (1) a memory cell pack; and (2) a method for forming a joint connection.

Description

The invention relates to a joint connection between a pole terminal of an electrical storage cell and a pole connector according to the combination of features of claim 1 of the invention. Furthermore, the invention according to claim 8 relates to a memory cell pack with a plurality of such memory cells and according to claim 10, a method for producing said joint connection.

Electrical conductors, also referred to as pole connectors or busbars, have long been known in the prior art in order to connect or interconnect a plurality of memory cells with one another to form a memory cell pack. Said storage cells, which may be batteries or accumulators, are connected in parallel and / or in series or in series, in order to achieve a specific capacity, a higher current carrying capacity and / or a higher total voltage for a particular application. So is out of the DE 198 47 190 A1 a connection plate for a battery holder for connecting a plurality of batteries in series, the connection plate comprising a synthetic resin plate into which bus bars are integrally molded by injection molding. Each bus bar is formed as a rectangular section plate member through which a large current can flow. The busbar has two ends each a hole for fastening the busbar by means of a fastening screw to a terminal pole or pole terminal of a battery to be connected, wherein said fastening screw is screwed into a threaded bore of the terminal pole. The WO 2011/038908 A1 describes a cell connector in the form of single connectors for connecting battery cells arranged in series to a battery pack. The present particular multi-bow-shaped cell connectors are made of a sheet material with sufficient spring and power line properties, such as sheet steel, copper, a copper alloy, aluminum or an aluminum alloy and are fixed to a mounting plate made of electrically insulating material. Holes are formed in the vertex areas of the brackets of a cell connector whose center distance corresponds approximately to the center distance of the cell poles connected together by means of the cell connector. The hole geometry is smaller than the end face of the cell pole pressing against the hole in the apex region. Approximately coaxial with each hole, the mounting plate through openings, through which and the hole through the end face of the cell pole with the edge of the hole permanently electrically conductive, namely materially connected by laser welding in particular, whereby a low-resistance connection between the joining partners is effected. Essentially, a fillet weld is produced in this case. Finally it is off the DE 10 2010 039 893 A1 Known to add a first with a second joining partner, namely a terminal pole of a battery with a cell connector so by lap joint by means of a laser welding process that the weld at least partially oscillates back and forth between the joining partners, whereby the heat input into the joint partners mitigated and thermal damage the same should be prevented. It is to be noted, so to speak, an oscillating weld depth. The said welding depth profile is generated by a variation of the laser power via a relative advancing movement of the laser relative to the joining partners.

On this basis, it is an object of the invention to further optimize a joint connection between a pole terminal of an electrical storage cell and a pole connector. According to a further aspect of the invention, it is the object of the same to provide a memory cell pack with a plurality of such memory cells and to provide a method for producing said joint connection.

The object is achieved first with a joint connection between a pole terminal of an electrical storage cell and a pole connector, wherein the pole terminal and the pole connector, forming a lap joint, are connected to one another by laser welding with the aid of at least one laser source with Mehrfokustechnik cohesively.

As a result of said Mehrfokustechnik is compared to a conventional single focus an extremely stable laser welding process feasible, which in turn is associated with a high-quality weld and high welding speeds advantageous.

The subclaims describe preferred developments or refinements of the invention.

According to a preferred embodiment of the invention, said Mehrfokustechnik is formed by a double FOT technology with seen in the feed direction of the focal points of the laser beams parallel or tandem arrangement of said focus points, whereby depending on the weld to be realized, in particular their weld depth and seam width, the mechanical complexity in relation to the welding performance particularly optimal. In contrast, a focus matrix technique with three or more focus points is also covered by the invention, whereby the mechanical engineering effort is increased, but the welding performance is even further improved. To the punctiform heat input and thus to minimize the thermal load, in particular the memory cell during the welding process, an I-weld, preferably a straight I-weld is provided for cohesive connection of the joining partner Polterminal and pole connector. A sufficiently strong joining compound with a low electrical contact resistance between the joining partners Polterminal and pole connector can be achieved if a weld is formed whose depth "t" corresponds to about 85% to about 95%, preferably about 91% of the total material thickness "s" of the two joining partners ,

Preferably, the direct connection surface "A" realized by the weld seam should be at least 10 mm ² , preferably approximately 15 to approximately 20 mm ² per 100 A to be ensured current carrying capacity in the joining region of the joining partner Polterminal and Polverbinder. This has a further advantageous effect with regard to a solid joining composite to be achieved with a low electrical contact resistance. According to a simple and inexpensive embodiment of the invention, the pole terminal and the pole connector are plate-shaped, whereby on the one hand the completion of the memory cell (s) with pole connectors and, on the other hand, the joining process per se are simplified. As the material for the pole terminal and the pole connector is preferably selected aluminum or an aluminum alloy, which is inexpensive and combines a good current conductivity with a good weldability with respect to laser beam welding.

• – weniger Bauraumbedarf
• – geringere Toleranzempfindlichkeit
• – geringerer Montageaufwand
• – geringeres Gewicht
• – keine mechanische Belastung der Batteriezellen.

From the application of a laser welding process in battery production, the following further advantages generally result:

• - less space required
• - lower tolerance sensitivity
• - Lower installation costs
• - lower weight
• - no mechanical stress on the battery cells.

The invention also relates to a memory cell pack having a plurality of arranged in a housing and interconnected by means of pole connector in parallel and / or series electrical memory cells, wherein the memory cells Polterminals having a / the pole connector, forming a lap joint, with the aid of at least one Laser source with Mehrfokustechnik interconnected materially connected by laser welding. Advantageously, the pole connectors are supported on a mounting plate by form, force and / or material connection that the same by means of the mounting plate with its one side can be placed simultaneously on the Polterminals concerned and from the other side by laser welding to the respective Polterminals , By this measure, the completion of the memory cells of the memory cell pack is simplified with said pole connectors.

The method for producing a joint connection between a pole terminal of an electrical storage cell and a pole connector is characterized in that the pole terminal and the pole connector, forming a lap joint, are connected to one another in a material-locking manner by laser welding with the aid of at least one laser source with multi-focal technology.

The invention is explained below with reference to the embodiment schematically illustrated in the drawings. Show it:

1 1 is a perspective view of a first embodiment of a memory cell pack having a plurality of electrical memory cells arranged in a housing and interconnected by means of a pole connector, according to the prior art;

2 1 is a perspective view of a second embodiment of a memory cell pack according to the prior art with a mounting plate, by means of which a plurality of pole connectors are integrally combined,

3 a perspective view of a memory cell pack with a mounting plate and held by the same pole connectors, immediately before joining the pole terminals of the memory cells with the pole connectors according to the invention,

4 an individual perspective view of a memory cell of the memory cell pack after 3 .

5 an individual perspective view of a mounting plate of the memory cell pack after 3 for holding the pole connector (detail "Z" after 3 )

6 a perspective view of an inventively designed memory cell pack in the final assembly state with memory cells, the Polterminals are joined with pole connectors (detail "Y" after 3 )

7a Very schematically a first embodiment (single-focus technique) and a second embodiment (dual-field technique) of a laser welding arrangement for materially joining a pole terminal of a memory cell with a pole connector,

8a -D with respect to the double-focus technique very schematically exemplifying four embodiments of the laser optics,

9a -B with respect to the double-focus technique exemplifying two arrangements of the realized by the laser optics focus points, and

10 very schematically a perspective sectional view of a joint connection between a pole terminal of a memory cell and a pole connector, realized according to the invention with a laser source with dual-fold technology.

1 first shows a memory cell pack 1 according to the prior art, which by a plurality in a housing 2 arranged electrical memory cells 3 is formed and in particular the supply of electric vehicles with electrical energy is used. The said memory cells 3 are predominantly formed by lithium ion accumulators. Each of the present prismatic memory cells 3 has two pole terminals 4 (Plus and minus pole) on. The pole terminals 4 are each by a base plate 5 and a bolt connected thereto in the form of a threaded bolt 6 , in particular a welding stud formed. To the said memory cells 3 can connect together in parallel and / or series connection, so-called pole connector 7 provided, which in turn are plate-shaped and according to the number of memory cells to be interconnected 3 mounting holes 8th exhibit. The pole connectors 7 are thus on the relevant threaded bolt 6 threadable and are on the base plates 5 stored. By means of said threaded bolts 6 screwed nut 9 becomes each pole connector 7 non-positively with the relevant Polterminals 4 the memory cells 3 positively connected.

2 shows a development of the memory cell pack 1 in the prior art in that said pole connector 7 from a mounting plate 10 are held in a positive, force and / or material fit. It is a module created which a fast and therefore inexpensive assembly of the memory cells 3 with pole connectors 7 allowed. Preferably, the mounting plate 10 of an electrically insulating material, in particular a plastic. In the present case are the pole connectors 7 with the mounting plate 10 by means of clip connection 11 (see esp. 6 ) positively connected. In contrast, the pole connector 7 also in the production of the mounting plate 10 for example, after a plastic injection molding process already injected into the same (not shown in the drawing).

To the joint connection between a pole terminal 4 an electrical storage cell 3 and a pole connector 7 to optimize further, the invention provides that the pole terminal 4 and the pole connector 7 , forming a lap joint, with the aid of at least one laser source 12 With Mehrfokustechnik interconnected material by laser welding are connected (see. 7b to 8d ).

These are in accordance with the 3 and 4 in the case 2 of the memory cell pack 1 a plurality of memory cells to be interconnected in parallel and / or series connection 3 arranged, their pole terminals 4 exclusively flat, ie formed plate-shaped. Equipped such plate-shaped pole terminals 4 with plate-shaped pole connectors 7 that plan on said pole terminals 4 be hung up. To the assembly of the Polterminals 4 with such pole connectors 7 To simplify, are based on the above-described prior art, the pole connector 7 also an integral part of a mounting plate 10 of an electrically insulating material, in particular a plastic, and by form, force and / or material connection to the mounting plate 10 held (cf. 3 . 5 and 6 ).

Are the plate-shaped pole connector 7 now simultaneously, ie in a single assembly step, by means of the mounting plate 10 with her one side on the relevant plate-shaped pole terminals 4 attached, they can from the other side after the above-mentioned laser welding process with the aid of at least one laser source 12 with Mehrfokustechnik with said Polterminals 4 be connected cohesively in the lap joint. Preferably, the pole terminals exist 4 and pole connectors 7 from a low-cost aluminum or an aluminum alloy. With aluminum or an aluminum alloy, a material is selected which combines a good current conductivity with a good weldability with respect to said laser beam welding.

The multi-technology according to the 7b . 8a -D is used in comparison to the conventional single-frame technology according to 7a (a focal point 13 ) essentially the process stabilization in the laser welding of aluminum or aluminum alloys by means of laser beam 14 ; 14a . 14b in particular for stabilizing the vapor capillary forming during welding 15 , By using multiple focus points at the same time 13a . 13b ( 7b ) succeeds in comparison to the single-focus technique ( 7a ), the diameter of said vapor capillary 15 To increase, in this way an adverse constriction of the vapor capillary 15 to prevent and finally the unhindered outflow of the during welding To ensure educating metal vapor. The outflow of metal vapor is the basic prerequisite for a stable laser welding process. The laser-specific weld seam defects, in particular in the case of aluminum, in the form of process pores and molten bath ejections can be greatly reduced or even avoided. The result is a high quality weld 16 to record ( 6 and 10 ).

The 8a -D represent without any claim to completeness very schematically four preferred embodiments of the laser optics / s 17 from laser sources 12 with preferred double-fold technique. So shows 8a two separate processing respectively laser optics 17a . 17b which each have a laser source 12a . 12b assigned. Here is a so-called addition of laser beams 14a . 14b to record at which the focus points 13a . 13b during the laser welding process with a specific focus diameter d _F "and at a specific focal distance" a "in longitudinal or tandem arrangement ( 9a ) or in parallel arrangement ( 9b ) in the feed direction 18 relative to the joining partners Polterminal 4 and pole connectors 7 be guided. According to 8b In contrast, a so-called double fiber is used. The double fiber becomes the laser beams 14a . 14b from two laser sources 12a . 12b in a fiber optic cable 19 with two cores 20a . 20b coupled and then on the same laser optics 17 focused. Furthermore, it is also possible with a correspondingly high laser power, for example, by means of optical wedge plate 21 ( 8c ) or a split mirror 22 ( 8d ) a laser beam 14 to share and thus two focus points 13a . 13b to create.

The above-described embodiments of the laser optics 17 ; 17a . 17b refer to said double-fold technique with the result two focus points 13a . 13b , However, a so-called focus matrix with three or more focus points is also covered by the invention 13a . 13b . 13c , ... in various arrangements (not shown graphically).

According to the 6 and 10 is presently the material connection of the joining partners Polterminal 4 and pole connectors 7 in the lap joint an I-weld 16 , preferably a straight I-weld 16 formed, whereby a predominantly punctual heat input into said joint partner Polterminal 4 and pole connectors 7 avoided and any thermal overload, in particular the memory cell 3 avoided during the welding process. Furthermore, in an I-weld 16 , which is considered in hindsight to be out of order, easier a second I-weld 16 be applied than in a preferred by the prior art fillet weld.

As already stated above, it has been found in extensive experiments relating to the subject matter of the invention that a sufficiently strong joining compound with low electrical contact resistance between the joining partners Polterminal 4 and pole connectors 7 achievable when the weld 16 a depth "t" of about 85% to about 95%, preferably about 91% of the total material thickness "s" of the two joining partner Polterminal 4 and pole connectors 7 having ( 10 ). Preferably, that is through the weld 16 realized immediate connection surface "A" at least 10 mm ² , preferably about 15 to about 20 mm ² per 100 A to be ensured current carrying capacity in the joint area of the joint partner Polterminal 4 and pole connectors 7 , This has a further advantageous effect with regard to a solid joining composite with low electrical contact resistance to be achieved.

According to a preferred laser welding arrangement, high welding depths "t" of .about.3 m / min are desirable with respect to a double focus optics at a focal distance "a" of about 0.6 mm, a parallel focus arrangement, a laser power of 4,200 to 4,300 W and a feed speed of the laser ≥ 3.5 mm achievable. At a material thickness "s ₁ " of the pole terminal 4 made of aluminum of 1.8 mm and a material thickness "s _2" of said pole 7 made of aluminum of 2.5 mm was found in the test specifically a weld depth "t" of 3.9 mm. The width "b" of the attachment surface "A" was 2 mm.

LIST OF REFERENCE NUMBERS

1

Memory cell pack

2

casing

3

memory cell

4

Polterminal

5

baseplate

6

threaded bolt

7

pole connector

8th

location hole

9

threaded nut

10

mounting plate

11

clip connection

12

laser source

12a, b

laser sources

13

focus point

13a, b

focal points

14

laser beam

14a, b

laser beams

15

vapor capillary

16

Weld

17

laser optics

17a, b

laser optics

18

feed direction

19

optical cable

20a, b

Cores (fiber optic cable 19 )

21

optical wedge plate

22

split mirror

" _F "

Focus diameter

"A"

focus distance

"T"

welding depth

"S"

Total material thickness of the joint partner Polterminal 4 and pole connectors 7

"S ₁ "

Material thickness Polterminal 4

"S ₂ "

Material thickness of the pole connector 7

"A"

through the weld 16 realized connection surface between the joining partners Polterminal 4 and pole connectors 7 (Adhesive bond)

"B"

Width of the connection surface "A"

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19847190 A1 [0002]
• WO 2011/038908 A1 [0002]
• DE 102010039893 A1 [0002]

Claims (10)

Joint connection between a pole terminal ( 4 ) an electrical storage cell ( 3 ) and a pole connector ( 7 ), whereby the pole terminal ( 4 ) and the pole connector ( 7 ), forming a lap joint, with the aid of at least one laser source ( 12 ; 12a . 12b ) are connected to each other by means of laser welding material-locking with multi-technology. Joint connection according to claim 1, characterized in that said Mehrfokustechnik a - double-fold technology with in the feed direction ( 18 ) of the focus points ( 13a . 13b ) of the laser beams ( 14a . 14b ) parallel or tandem arrangement of said focus points ( 13a . 13b ) or one - focus matrix technique with three or more focus points ( 13a . 13b . 13c , ...) is. Joining connection according to claim 1 or 2, characterized in that for the cohesive connection of pole terminal ( 4 ) and pole connectors ( 7 ) an I-weld ( 16 ), preferably a rectilinear I-weld ( 16 ) is trained. Joining connection according to one of claims 1 to 3, characterized in that for the cohesive connection of Polterminal ( 4 ) and pole connectors ( 7 ) a weld ( 16 ) is formed, the depth "t" corresponds to about 85% to about 95%, preferably about 91% of the total material thickness "s" of the two joining partners. Joining connection according to one of claims 1 to 4, characterized in that the weld ( 16 ) is formed such that through the weld ( 16 ) realized immediate connection surface "A" at least 10 mm ² , preferably about 15 to about 20 mm ² per 100 A to be ensured current carrying capacity in the joining area of Polterminal ( 4 ) and pole connectors ( 7 ) is. Joining connection according to one of claims 1 to 5, characterized in that the pole terminal ( 4 ) and the pole connector ( 7 ) are plate-shaped. Joining connection according to one of claims 1 to 6, characterized in that the pole terminal ( 4 ) and the pole connector ( 7 ) consist of aluminum or an aluminum alloy. Memory cell pack ( 1 ) with a plurality in a housing ( 2 ) arranged and by means of pole connector ( 7 ) in parallel and / or series connection of interconnected electrical memory cells ( 3 ), wherein the memory cells ( 3 ) Polterminals ( 4 ) with a / the pole connector ( 7 ), forming a lap joint, with the aid of at least one laser source ( 12 ; 12a . 12b ) are connected to each other by means of laser welding material-locking with multi-technology. Memory cell pack ( 1 ) according to claim 7, characterized in that the pole connectors ( 7 ) on a mounting plate ( 10 ) are held by form, force and / or material connection such that the same by means of the mounting plate ( 10 ) with its one side at the same time on the Polterminals concerned ( 4 ) and from the other side by laser welding to the respective pole terminals ( 4 ) are connectable. Method for producing a joint connection between a pole terminal ( 4 ) an electrical storage cell ( 3 ) and a pole connector ( 7 ), whereby the pole terminal ( 4 ) and the pole connector ( 7 ), forming a lap joint, with the aid of at least one laser source ( 12 ; 12a . 12b ) with Mehrfokustechnik interconnected by laser welding.

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