EP2115815A1

EP2115815A1 - Process for manufacturing a cable for connecting the poles of a battery, an installation for implementing said process, and the cable obtained

Info

Publication number: EP2115815A1
Application number: EP08762022A
Authority: EP
Inventors: Lucien Weis; Eric Mandel
Original assignee: Powerconn; Pulsar Ltd
Current assignee: Powerconn; Pulsar Ltd
Priority date: 2007-01-31
Filing date: 2008-01-31
Publication date: 2009-11-11
Also published as: FR2912000A1; WO2008104668A1

Abstract

The present invention relates to a process for manufacturing a cable for connecting the poles of a battery, intended to join the galvanic cells thereof, which cable comprises a bundle consisting of a plurality of electrical conductor wires having a cross section between 16 mm<SUP>2</SUP> and 150 mm<SUP>2</SUP>, the two ends of said wires being fastened with a connector. According to the invention, this process consists: in preparing a cable bundle surrounded by an insulating material, with stripped ends; in preparing a connector having a tubular first part for being fastened to one of the ends of the bundle and a planar second part provided with an orifice; in inserting one of the stripped ends of the cable bundle into the tubular part of said connector; in applying an annular electromagnetic field around said tubular part, the energy level of said field being between 6 and 8 kJ, at a voltage of 5 to 7.5 kV, applied for between 8 and 100 µs, so as to create magnetic forces causing the diameter of at least a portion of the length of said tubular part to shrink very rapidly, by plastic deformation, in order to obtain the desired assembly; in carrying out the same assembly operation at the other stripped end of the bundle, using another connector; and then in encapsulating the two connectors and the possible uninsulated portions of said cable bundle with an insulating material.

Description

METHOD FOR MANUFACTURING A CABLE FOR CONNECTING BATTERY POLES, THE INSTALLATION FOR IMPLEMENTATION AND THE CABLE OBTAINED

The present invention relates to battery pole connecting cables which are intended to interconnect galvanic cells. Such connection cables, also called "cables" are intended to conduct relatively large currents (of the order of 300 Ah to 1800 Ah) and must have a low electrical resistance.

These cables comprise a bundle consisting of a plurality of electrical conductors son whose two ends are secured to a connector provided with an orifice, allowing the connection with one of the poles of the battery, the assembly being completely surrounded by a insulation material. In general, these connection cables have a distance between 75 and 300 mm (distance between the axis of the orifices of the two end connectors); for terminal equipment, these lengths can be between 800 mm and 1500 mm. On the other hand, the section of the bundle of conductive wires is relatively large, between 16 mm ² and 150 mm ² . In particular, for stationary batteries, this section is generally between 70 and 120 mm ² ; for traction batteries, for example forklift batteries, this section is generally between 16 and 70 mm ² .

These battery pole connecting cables are special cables for the conduction of high currents. For security reasons, they need to be completely covered with an insulating material. On the other hand, the connection between the end connectors and the ends of the cable harness must be as perfect as possible in order to limit the electrical resistance and ensure good mechanical strength.

US-4,049,335 discloses a conventional technique for making such a battery pole connecting cable.

In this document, the connection cable comprises a beam composed of a multiplicity of fine wires equipped at both ends with a connector provided with an orifice. For the manufacture of the cable, each connector here consists of a tubular copper sheath into which is introduced a portion of the previously partially stripped beam. Then, the copper sheath is compressed and flattened with the beam so as to assemble the two elements.

An orifice is then formed in the flattened zone of the copper sheath. Finally, the periphery of the orifice receives a brazing material in order to improve the assembly of the elements and the electrical conductivity. The ends of the connection cable thus produced are then covered with an insulating material by a molding-injection technique.

The hole in the connector allows the latter to be positioned on a screw formed in the battery pole and to be pressed by means of a clamping nut.

However, the assembly between the reported connector and the fine wire bundle is not optimal. In addition, the flattened portion of the cable consists of two outer material layers sandwiching the wire bundle and this non-homogeneous structure can cause loosening of the nut, particularly on non-stationary accumulators arranged in vehicles. , subjected to repetitive shaking. The end of the cable is then no longer effectively connected to the accumulator pole which leads to electrical conduction defects, and to heating sometimes up to the formation of sparks.

To overcome these drawbacks, document EP-1 101 255 proposes a connection cable whose connectors are in the form of plates assembled by ultrasonic welding with the ends of the bundle son. Conventionally, the stripped ends of the fine wire bundle are then wrapped with an insulating material.

This technology provides different advantages over the previous one described above, in particular in terms of reduction of material, strength, electrical conductivity quality, mechanical strength over time and speed of manufacture.

However, the weld type bond, by an energy supply action in the form of heat, causes the liquefaction of the two materials to be assembled, at their joint plane; and during cooling, the molten materials mix and assemble by molecular bonding.

However, this recrystallization operation inevitably generates, after cooling, a molecular and metallographic structure different from that of origin of the two components to be assembled.

In practice, this modified area is called ZAT (Zone Affectée Thermiquement). The perverse effect of this ZAT is, through the modification of the metallography of the materials in this zone, to create in particular microcracks, pollution and a third type of material, resulting in: - a lowering of the mechanical characteristics the connection to the characteristics of the base material, to no longer allow any durability of these mechanical characteristics over time, by the presence of microcracks which, under the action of the stresses of the assembled components, will develop in time until they break,

to lower in the connection zone the electrical and dielectric characteristics of the base materials, and

- to create chemical destructions by stack effect between the third material and the base material in the environment of use.

In addition, it is very difficult to weld together two different materials, so that in a very general manner, the connection cables currently on the market include a bundle of thin copper wires, associated with end connectors also in copper, because of the good electrical conductivity of this material, but what makes these connection cables relatively expensive, because of the price of copper on the market.

In the general field of cables with end connector (s), it is also known, from documents WO-97/22426 or WO-98/23400, the possibility of introducing one of the stripped ends of the cable into a tubular housing of the connector and to use a magnetoforming technique "puise magnetic forming - PMF" to achieve the desired assembly.

However, the conditions of implementation of this technique, if they are well suited to the connection of end connectors with electrical cables of small section, do not provide an assembly of sufficient quality for battery cables.

It persists in fact microscopic air pockets between the connector and the peripheral fine wires of the cable and / or between the thin wires of the cable between them, which degrade the mechanical and electrical performance of the assembly and which are a source of corrosion. possible in time.

The document WO-2005/055371 describes a technical solution derived from the two aforementioned documents WO-97/22426 and WO-98/23400, applied in particular to battery cables, consisting in coating the end of the cable with a "fuse" material. conductor of electricity, before inserting this end "coated" in the cylindrical housing of the connector and implement the electromagnetic assembly technique.

The fuse material used eliminates the presence of air pockets and optimizes the electrical conductivity of the connection. However, this coating consists of an additional technical operation that is costly (in terms of material cost and in terms of implementation time) that is difficult to comply with industrial requirements.

The applicants have developed a new method of manufacturing such battery pole connecting cables intended to overcome these disadvantages.

According to the present invention, the method in question is characterized in that it consists of:

to prepare a bundle surrounded by an insulating material with stripped ends which have a nominal diameter (a),

preparing a connector which comprises a first tube-shaped portion of constant internal and external cross-section for securing it to one of said beam ends, and a second flat portion provided with an orifice adapted to be secured to the battery pole, the nominal internal diameter (d) of said tubular portion being between 1, 10 and 1, 20 times the nominal diameter (a) of said end of the wire bundle, and the nominal external diameter (β) of said tubular portion being between 1.45 and 1.65 times the nominal diameter (a) of said end,

inserting one of the stripped ends of the bundle into said first tube-shaped portion of said connector,

- To implement around said tubular portion an annular electromagnetic field whose energy level is between 6 and 8 kJ, at a voltage of 5 to 7.5 kV, applied between 8 and 100 μs, so as to create magnetic forces causing the high velocity shrinkage of the diameter of at least a portion of the length of said tubular portion, by plastic deformation, to obtain the desired assembly,

- to perform the same assembly operation at the other bare end of the beam with another connector, then

- To cover with an insulating material, the two connectors and any parts of said beam uninsulated.

The implementation of such an assembly technique called "Magnetic Puise Welding (MPW)" provides a very efficient connection both mechanically and electrically, very suitable for battery cables. At the level of the assembly, a nearly one-piece metal mass is obtained which no longer makes it possible to individualize the multiple wires of the bundle or the tubular portion of the connector. The magnetic field implemented around the parts to be assembled is specially defined and constructed for the present specific application. This field causes the creation of forces that will ensure the percussion parts to assemble at very high speed; the impact caused by this encounter leads, by its power, the atomic decohesion of the atoms of the molecules of the contact surfaces. The electrons of each nucleus are torn from their orbit and reposition themselves in orbits different from those of origin. After recombination, the equilibrium and stability of the material are assured again.

This results in a high quality assembly between the end of the conductive wire bundle and end connectors, totally different nature of conventional assemblies. The assembly in question is in particular devoid of ZAT; it greatly limits or even eliminates the presence of internal air pockets. It causes little or no microcracks or pollution; it also makes it possible to obtain excellent conductivity and excellent behavior results when the current passes, as well as excellent results in terms of mechanical strength. The corresponding assembly can also be realized very quickly, which allows to obtain very high production rates.

Preferably, the application time of the electromagnetic field is of the order of 80 μs.

According to another feature, the method consists in implementing an electromagnetic field by means of an installation comprising capacitors, a transformer and a solid block generating said electromagnetic field in which is formed an insertion opening of the tube of said connector; said capacitors are charged by a current of between 500 and 600 kA, to generate a current whose frequency is between 10 and 15 kH, discharged into said solid block via the transformer.

Still preferably, the electromagnetic field is generated in the opening of a solid Beryllium Copper block, its electromagnetic field application aperture having a length of between 8 and 20 mm and a circular shape with a diameter of a few tenths of a millimeter larger than the nominal outside diameter (β) of the tubular connector portion.

The invention also relates to the installation for implementing the method defined above, this installation comprising capacitors, a transformer and a solid electromagnetic field generating block, which solid block comprises a circular opening whose length is between 8 and 20 mm and which presents a circular shape whose diameter is a few tenths of a mm greater than the nominal external diameter (Ë) of said tubular connector portion.

According to a particular embodiment, the installation comprises means for discharging into the solid Beryllium Copper block, via the transformer, a frequency current of between 10 and 15 kH and generating in said massive block an electromagnetic field whose energy level is between 6 and 8 kJ under a voltage of 5 to 7.5 Kv.

The invention further relates to the battery pole connecting cable for connecting galvanic cells, obtained by the method defined above. This cable comprises a bundle consisting of a plurality of electrical conductors son whose two ends are each secured to a connector for connection with one of the poles of the battery, which connector, also made of conductive material, comprises a first part for its attachment to the corresponding end of said beam, and a second portion, flat, provided with a hole adapted for its attachment to said battery pole, said beam and said connectors being completely surrounded by an insulating material. Said first connector portion is in the general shape of a tube delimiting a cylindrical orifice in which said beam end is housed, the nominal internal diameter (d), before assembly, of the tubular part of the connector being between 1, 10 and 1 , 20 times the nominal diameter (a) of the end of the bundle of wires, the nominal external diameter (β) of said tubular portion being between 1.45 and 1.65 times the nominal diameter (a) of said end of beam, the wall thickness (b) of said tubular portion being of the order of 1.8 mm, and said tube being secured to said beam end by an electromagnetic assembly technique of "Magnetic Puise Welding" type - MPW.

This specific technique of electromagnetic assembly also very advantageously makes it possible to bond between them materials different from copper, traditionally used in the present application, and also materials of different nature.

In particular, according to a first possible embodiment, the battery cable according to the invention comprises a bundle consisting of aluminum wires, associated with end connectors also made of aluminum.

In a second interesting embodiment, the beam is made of copper wires, and the end connectors are made of aluminum. The invention will be further illustrated, without being limited in any way, by the following description in conjunction with the accompanying drawings in which:

- Figure 1 is a general perspective view of a plurality of batteries connected to each other in parallel by means of connecting cables according to the invention;

- Figure 2 is a perspective view of one end of a connecting cable according to the invention, during manufacture, before assembling the end connector with the stripped end of the son of conductor bundle;

- Figure 3 is a sectional view along 3-3 of Figure 2;

FIG. 4 is a schematic view illustrating the application of the electromagnetic field to assemble the connector and the end of the bundle of conductive wires;

FIG. 5 is a perspective view of the end of the connection cable shown in FIG. 2, after implementation of the electromagnetic field and assembly of the connector with the end of the bundle of conductive wires;

- Figure 6 is a sectional view along 6-6 of Figure 5;

FIG. 7 is a perspective view of the connection cable consisting of the bundle of conductive wires at the stripped ends of which the two connectors are fixed, before coating of the latter with an insulating material;

- Figure 8 is a perspective view of the connecting cable of Figure 7, after embedding the end connectors by the insulating material.

FIG. 1 shows a plurality of batteries 1 connected in parallel by connection cables 2 (or cables) according to the present invention, each consisting of a bundle of conducting wires 3 at both ends of which connector members 4 are fixed.

The connector members 4 are provided with an orifice 5 enabling them to be connected to the poles in the form of threaded holes in the batteries 1, by means of screws 7.

The manufacture of the connection cables 2 according to the invention is described below in conjunction with FIGS. 2 to 8. To make such a cable 2, the two ends 8 of a bundle of conductive wires 3 coated with an insulating material 9 (for example a plastic PVC or rubber); as illustrated in FIGS. 2 and 3, each of these stripped ends 8 is introduced into the tubular portion 10 of a previously prepared end connector 4; the bundle end 8 / tubular connector 10 4 is then subjected to the action of a annular electromagnetic field adapted to assemble them (FIGS. 4, 5 and 6); and finally the ends of cables thus obtained are coated with an insulating material (Figures 7 and 8).

The insulated beam 3 comprises a multiplicity of fine wires of conductive material, for example copper or aluminum.

In particular, the beam 3 may consist of a multiplicity of purposes son each having a diameter of between 20/100 and 60/100 ^th of ^th mm. For example, for wires having a diameter of 20/100 ^th of mm, approximately:

- 780 threads to produce a bundle 3 having a section of 25 mm ² ,

- 1 100 threads to make a bundle 3 having a section of 35 mm ² , - 1550 threads to produce a bundle 3 having a section of 50 mm ² ,

- 2200 wires to make a beam 3 having a section of 70 mm ² ,

- 2950 son to make a beam 3 having a section of 95 mm ² .

Each connector 4 is also made of conductive material, for example copper or aluminum. This connector 4 comprises a first tubular portion 10 delimiting a cylindrical orifice 1 1, for its attachment to one of the stripped ends of the bundle 3, and a second flat portion 12, integrally formed with the first part 1 1, provided with the orifice 5 for its attachment to the pole of the battery 1.

To obtain an optimal assembly:

- The nominal internal diameter d of the tubular portion 10 of the connector 4, before assembly with the stripped end 8 of the bundle of conductive wires 3 is between 1, 10 and 1, 20 times the nominal diameter a of the denuded end 8 said bundle of wires 3 (FIG. 3);

the nominal external diameter p of said tubular connector portion 4 is between 1.45 and 1.65 times the nominal diameter a of said beam 3, and

- The thickness of the tubular portion 10 of the connector 4 is of the order of 1.8 mm, regardless of the section of said bundle of conductive wires 3.

The stripped end 8 of the bundle 3 is driven as far as possible into the cylindrical orifice 1 1 of the tubular portion 10 of the connector 4, the length of which is between 5 and 20 mm (advantageously of the order of 8 to 10 mm). , and the electromagnetic assembly field is applied annularly over all or substantially the entire length of the tubular portion 10 of the connector 4 (Figure 4). The assembly technique by "Magnetic Puise Welding - MPW" uses a solid block pierced, producing a very powerful and very short electromagnetic field to generate mechanical forces capable of causing a cold deformation of a metallic material

As illustrated diagrammatically in FIG. 4, an "MPW" machine essentially comprises a generator 13 associated with a set of capacitors 14, a transformer (not shown) and a solid block 15 in which an opening for insertion is provided. of the tubular piece 10 to be deformed.

By discharging the capacitances 14 through the solid block 15 in a few microseconds, a brief intense magnetic pulse is generated which induces currents in the piece placed in the coil. The induced current circulating on the surface of the part 10, and that of the solid block 15, generate radial repulsion forces which cause the deformation of the metal at a very high speed.

The charging current of the capacitors 14 may be 540 kA; the inductance measurement of these capacitances 14 may be 120 nH.

These capacitors 14 are capable of generating a specific current whose frequency is between 10 and 15 kH which is discharged into the solid block 15 to create a specific magnetic field whose energy level is between 6 and 8 kJ under a voltage from 5 to 7.5 kV (depending on the diameter of the wire harness 3).

The electromagnetic field is applied for a time of 8 to 100 microseconds (preferably close to 80 μs) to achieve the assembly. For example, it is possible to implement an energy of the order of 7 kJ for a 25 mm ² cable, and 7.5 kJ for a 70 mm ² cable.

The solid block 15 is advantageously made of Beryllium Copper with a cylindrical insertion opening. The circular section of this opening is a few tenths of a millimeter larger than the external nominal diameter (p_) of the tube 10; its length can be of the order of 10 to 15 mm, depending on the maximum assembly length that is desired.

For this purpose, it is possible to use a magnetization machine of the MPW30 type proposed by the company PULSAR WELDING LTD.

A connection cable is obtained after assembly, one of the ends of which is illustrated in FIGS. 5 and 6. Following this assembly, the external diameter ç of the tubular portion 10 of the connector 4 is substantially reduced with respect to its nominal diameter. before assembly. Similarly, because of the compression realized, the diameter of the end 8 of the beam 3 is also reduced relative to the nominal diameter a.

Such an assembly is very efficient and shows on examination a lack of ZAT at the connection zone between the wire bundle 3 and the tubular portion 10 connector. The mechanical strength and conductivity tests performed are very positive.

In addition, this type of fastening technique allows the assembly of difficult or non-weldable materials, such as aluminum / aluminum or copper / aluminum.

It is therefore possible to envisage making connection cables comprising a bundle of copper conductor wires 3, associated with aluminum end connectors 4, or else a bundle of aluminum conductive wires associated with aluminum end connectors 4. .

After assembly, the ends of the connecting cable are placed in an injection mold to receive a coating 16 of insulating material like PVC or rubber for example.

The fully insulated connecting cable 2 illustrated in FIG. 8 is obtained and suitable for use in connecting battery poles as shown in FIG. 1.

Claims

- CLAIMS -

1. A method for manufacturing a battery pole connecting cable comprising a bundle (3) consisting of a plurality of electrical conductor wires whose cross section is between 16 mm ² and 150 mm ² , and whose two ends (8) are secured with a connector (4), also made of conductive material, for connection to one of the poles of the battery (1), said beam (3) and said connectors (4) being completely surrounded by a insulation material (9, 16), characterized in that it consists of:

preparing a bundle (3) surrounded by an insulating material (9) with stripped ends which have a nominal diameter (a),

- preparing a connector (4) which comprises a first portion (10) in the form of a tube, of constant internal and external section, for its attachment to one of said beam ends (8) (3), and a second part plane (12) provided with an orifice (5) adapted to be secured to said battery pole, the nominal internal diameter (d) of said tubular portion (10) being between 1, 10 and 1, 20 times the nominal diameter (a) of said end (8) of the wire bundle (3), and the nominal outside diameter (Q) of said tubular portion (10) being between 1.45 and 1.65 times the nominal diameter (a) of said end (8),

inserting one of the stripped ends (8) of the bundle (3) into said first tube-shaped part (10) of said connector (4),

- To implement around said tubular portion (10) an annular electromagnetic field whose energy level is between 6 and 8 kJ, at a voltage of 5 to 7.5 kV, applied between 8 and 100 μs, in order to create magnetic forces causing the high velocity shrinkage of the diameter of at least a portion of the length of said tubular portion (10), by plastic deformation, to obtain the desired assembly,

to perform the same assembly operation at the other stripped end of the bundle (3) with another connector (4), then

- To cover with an insulating material (16), the two connectors (4) and any parts of said beam (3) uninsulated.

2. A method according to claim 1, characterized in that the application time of the electromagnetic field is of the order of 80 microseconds.

3. A method according to any one of claims 1 or 2, characterized in that it consists in implementing an electromagnetic field by means of an installation comprising capacitors (14), a transformer and a solid block (15). ) generator of said electromagnetic field in which is formed an insertion opening of the tube (10) of said connector (4), said capacitors (14) being charged by a current of between 500 and 600 kA, to generate a current whose frequency is included between 10 and 15 kH, discharged into said solid block (15) via the transformer.

4. A method according to claim 3, characterized in that the electromagnetic field is generated in the opening of a solid block (15) of Beryllium Copper, said opening having a length of between 8 and 20 mm and a circular shape whose diameter is a few tenths of a mm greater than the nominal external diameter (β) of said tubular portion (10) of connector (4).

5. Installation for the implementation of the method according to any one of claims 1 to 4, characterized in that it comprises capacitors (14), a transformer and a solid block (15) electromagnetic field generator, which solid block (15) has a circular opening whose length is between 8 and 20 mm and which has a circular shape whose diameter is a few tenths of a mm greater than the nominal external diameter (β) of said tubular portion (10) of connector (4).

6.- Installation according to claim 5, characterized in that it comprises means for discharging into the solid block of Beryllium Copper (15), through the transformer, a frequency current between 10 and 15 kH and generating in said solid block (15) an electromagnetic field whose energy level is between 6 and 8 kJ under a voltage of 5 to 7.5 kV.

7.- battery pole connecting cable for connecting galvanic cells, obtained by the method according to any one of claims 1 to 4, which cable (2) comprises a beam (3) consisting of a plurality of son electrical conductors whose two ends (8) are each secured to a connector (4) for connection with one of the poles of the battery (1), which connector (4), also made of conductive material, comprises a first part (10) for its attachment to the corresponding end (8) of said beam (3), and a second portion (12), flat, provided with an orifice (5) adapted for its attachment to said battery pole, said beam (3) and said connectors (4) being completely surrounded by an insulating material (9, 16), said first connector part (10) being in the general shape of a tube delimiting a cylindrical orifice (1 1) at within which is housed said extr mite (8) beam (3), the nominal inside diameter (d), before assembly, the tubular portion (10) of the connector (4) being between 1, 10 and 1, 20 times nominal diameter (a) of the end (8) of the wire bundle (3), the nominal external diameter (β) of said tubular portion (10) being between 1.45 and 1.65 times the nominal diameter (a) ) of said end (8) of beam (3), the wall thickness (b) of said tubular portion (10) being of the order of 1.8 mm, and said tube (10) being secured to said end (8) beam (3) by an electromagnetic assembly technique of the type "Magnetic Puise Welding" - MPW.

8.- Battery cable according to claim 7, characterized in that it comprises a beam (3) consisting of aluminum son associated with connectors (4) also aluminum.

9.- battery cable according to claim 7, characterized in that it comprises a beam (3) consisting of copper son associated with connectors (4) aluminum.