METHOD FOR MANUFACTURING A BATTERY CELL FOR AN ELECTRIC OR HYBRID VEHICLE

Abstract

A method for manufacturing a traction battery cell (2) for a motor vehicle, comprising on an upper face (4) two electrical contact pads (6), each pad (6) receiving a screw-on device (12) for an internal electrical connection to the battery. For each pad (6), this method comprises a step of fixing the screw-on device (12) to the surface of a support (10), forming a connector comprising a particular position of the screw-on device (12) on this surface corresponding to a type of battery to be produced, followed by a step of fixing the support (10) to the contact pad (6). Figure 3

Description

Title of the invention: METHOD FOR MANUFACTURING AN ELECTRIC OR HYBRID VEHICLE BATTERY CELL

[0001] The present invention relates to a method for manufacturing a traction battery cell for a motor vehicle, as well as a cell produced with such a method, a battery comprising these cells and a motor vehicle equipped with a battery comprising these cells.

[0002] Electric or hybrid motor vehicles comprise an electrical energy storage battery, consisting of modules connected together in series or in parallel, each module being formed by an assembly of cells connected together.

[0003] In this way, basic sub-assemblies are produced consisting of modules, each capable of delivering a voltage and an intensity depending on the series or parallel coupling of its cells in the module.

[0004] Then, depending on the needs of each hybrid or electric vehicle, modules are assembled to form a battery, connecting these modules together in series or in parallel depending on the configuration that we want to give to these vehicles.

[0005] In this way, from identical standard cells, which can be mass-produced economically, different battery configurations adapted to a range of vehicles are produced, each comprising its own voltage, capacity and dimensions.

[0006] Furthermore, a known type of battery, presented in particular by document EP-Al-2958165, comprises a set of flat cells which are stacked next to each other with transverse tightening provided by a spring, to obtain mechanical strength for this set and thermal conductivity allowing cooling.

[0007] Each cell has at the ends of its elongated upper face, symmetrically, an electrical contact pad forming a positive or negative pole, each comprising a fixing device receiving an electrical connection making it possible to connect these cells together. In particular, internal connection bars, called "busbars" in English, are used, forming rigid blades which are screwed onto the fixing devices of the pads to connect the cells together.

[0008] However, the symmetrical position of the contact pads on this type of cell, each receiving a fixing device positioned in the same way, gives cells and modules which can be arranged indifferently in one direction or the other. without changing the position of these fixings, with the same connecting bars that fit in all cases.

[0009] When assembling modules to manufacture different types of batteries suitable for various vehicles, each requiring a specific arrangement of the modules, errors may occur in the assembly of these modules. The battery then does not have the expected characteristics.

[0010] The present invention aims in particular to avoid these drawbacks of the prior art.

[0011] To this end, it proposes a method for manufacturing a traction battery cell for a motor vehicle, comprising on an upper face two electrical contact pads, each pad receiving a screwing device for an internal electrical connection to the battery, this method being remarkable in that for each pad it comprises a step of fixing the screwing device to the surface of a support, forming a connector comprising a particular position of the screwing device on this surface corresponding to a type of battery to be produced, then a step of fixing the support to the contact pad.

[0012] An advantage of this method is that by placing the fixing device in different places on the connection for several cells of the same module, it is thus possible to differentiate the cells in the same module, or to differentiate the modules formed.

[0013] Furthermore, by adapting the geometry of the connection busbar sets according to the type of battery each corresponding to a vehicle model, a control means is produced in a simple and economical manner preventing the assembly of non-corresponding modules on these bars, which avoids assembly errors.

[0014] The method according to the invention, and a cell formed with this method, may further comprise one or more of the following characteristics, which may be combined with each other.

[0015] Advantageously, the screwing device comprises a stud fixed perpendicularly to a plate constituting the support.

[0016] In this case, advantageously the stud is fixed to the plate by welding using an electric discharge.

[0017] Advantageously, the support having a contour corresponding to that of the pad is welded to this contour by laser welding.

[0018] Advantageously, the studs being arranged at the ends of the upper face of the cell which is elongated along a main axis, the screwing devices are, along this main axis, positioned on each stud towards the inside or towards the outside of the cell.

[0019] Advantageously, the studs being arranged at the ends of the upper face of the cell which is elongated along a main axis, for each stud the screwing devices are in the transverse direction positioned on one side or the other of the main axis.

[0020] The invention also relates to a module comprising two cells comprising any one of the preceding characteristics, comprising two pads of the two cells which are connected to each other, remarkable in that the positions of the screwing devices on these two pads are different from each other.

[0021] Advantageously, the screwing devices of the two studs are arranged along a diagonal of a rectangular surface formed by these two studs.

[0022] The invention further relates to a traction battery for an electric or hybrid motor vehicle, comprising modules comprising any one of the preceding characteristics.

[0023] The invention further relates to an electric or hybrid motor vehicle equipped with a traction battery comprising cells comprising any one of the preceding characteristics.

[0024] The invention will be better understood and other characteristics and advantages will appear more clearly on reading the description below given by way of example, with reference to the appended drawings in which:

[0025] [Fig-1] is a top view of a cell according to the prior art;

[0026] [Fig.2] shows successive stages of preparation of a cell according to the invention;

[0027] [Fig.3] is successively a top and side view of two cells according to the invention intended to form a module;

[0028] [Fig.4] is a top view of a battery composed of cells according to the invention;

[0029] [Fig.5] is a partial top view of a battery according to a first variant;

[0030] [Fig.6] is a partial top view of a battery according to a second variant; and

[0031] [Fig.7] is a partial view of a battery according to a third variant.

[0032] [Fig.l] shows a cell 2 comprising a parallelepiped shape, comprising a substantially flat upper face 4, elongated along a main axis A. Subsequently the axial direction corresponds to this main axis A of the cells 2, the transverse direction being perpendicular to this axial direction.

[0033] Each end of the upper face 4 receives, symmetrically with respect to a transverse axis B, an electrical contact pad 6 of rectangular shape, one having a positive pole and the other a negative pole of the cell.

[0034] Each contact pad 6 comprises a threaded vertical stud 12, the base of which is welded to the middle of this pad.

[0035] In this way, a symmetrical cell is obtained which can be placed indifferently in one direction or the other without changing the connection bar of the battery, because of the symmetry of the studs 12 of the positive and negative poles.

[0036] [Fig.2] shows on the first diagram a first step for each plot 6, of preparation of a particular connector constituting a subassembly, comprising a rectangular plate 10 forming a support corresponding to the outline of the pad, receiving by welding a vertical stud 12 fixed at a particular location on this plate.

[0037] Advantageously, the stud 12 is welded with an electric discharge weld, in particular by capacitor discharge, by forming at the lower end of the stud a point resting on the upper surface of the plate 10, then passing a strong electric current over this point which locally melts the metal on the two parts, and by applying vertical pressure on the stud to position it.

[0038] This type of welding makes it possible to position the stud 12 at any location on the plate 10, for example using a numerical positioning control on the welding machine making it possible to automatically carry out the particular positioning.

[0039] The second diagram of [Fig.2] shows the assembly of the connector, the plate 10 fitting onto the contour of the pad 6, with pressure applied to this pad, then a weld 14 of the plate onto this contour in order to achieve both strong mechanical strength and electrical conduction between the two flat surfaces resting on each other.

[0040] Advantageously, the welding of the contour 14 is carried out by laser welding, which has the advantage of not transmitting heat near this weld.

[0041] It will be noted that since the plates 10 are all identical, all the plates are welded to the pads 6 in a standard manner, regardless of the positioning of the stud 12.

[0042] In this way, a cell 2 is obtained comprising a particular positioning of its two screwing devices formed by the two studs 12, suitable for the preparation of a type of module grouping together several cells, corresponding to a battery model to be assembled.

[0043] [Fig. 3] shows a first cell 20 of a module comprising the studs 12 of the connectors arranged along the main axis A, axially towards the outer side of the plate 10 for a first screwing device, and towards the inner side for the second screwing device.

[0044] In practice, the same two connectors can be made, then soldered onto the pads 6 by positioning the two studs 12 towards the same axial side.

[0045] The second cell 22 of the same module comprises the two studs 12 welded to the plate 10 on the same axial side, in the transverse direction these two studs being fixed on either side of the main axis A.

[0046] The preparation of the cells 2 receiving the studs 12 in particular positions can be done directly at the cell manufacturer, or subsequently at a supplier preparing these cells for battery assembly.

[0047] By assembling the two cells 20, 22 against each other to form the module, different positions of the studs 12 at the ends of this module are obtained, which are not symmetrical both in the direction of the main axis A and the transverse axis B.

[0048] From specific connection bars adapted for the battery receiving this module, comprising particular drillings corresponding to the positions of the studs 12, it is not possible to turn a cell 20, 22, or to reverse the two cells between them, without giving a bad positioning of the studs not corresponding to these bars. Any bad assembly is impossible.

[0049] [Fig.4] shows a battery comprising a stack of six modules connected in series, each comprising two cells 2 connected in parallel, forming a rectangle clamped lengthwise by rods 30 framing this battery.

[0050] The rods 30 provide a clamping between a right end plate 32 bearing on the last cell 2, and a left end plate 34 compressing springs 38 which bear on an intermediate plate 36 in contact with the first cell. The springs 38 make it possible to apply a constant clamping force throughout the life of the battery, guaranteeing in particular mechanical maintenance of the assembly and thermal conduction between the cells 2.

[0051] The studs 12 of the cells 2 are on each side of the battery, aligned on the same transverse line arranged towards the axially outer side of each plate 10. On each module in the transverse direction the studs 12 are fixed towards the outside of the module. In this way it is not possible to turn a cell 2 over in a module without modifying the position of its studs 12.

[0052] An electrical circuit formed by flat connection bars 42, 44 cut from conductive sheets, with holes receiving the studs 12 tightened by nuts 46, comprises, starting from one end of this circuit, a short bar 42 connecting the two poles of a first module of the battery.

[0053] We then have on the other side of this first module, a long bar 44 connecting four poles of the two juxtaposed modules. We then continue in the same way with long bars 44, to finish at the end of the circuit with a short bar 42 connecting two poles of the last module.

[0054] [Fig.5] shows one side of a battery comprising six modules connected in series, each comprising two cells 2 connected in parallel.

[0055] On each end of a module, the studs 12 are fixed in the transverse direction to the outside of this module, along a diagonal of the rectangle formed by the two juxtaposed plates 10. The directions of the diagonals are alternated so as to have on the same long plate 44, the diagonals in two different directions, forming an angle between them.

[0056] By differentiating the other end of the modules, a reversal of these modules is prevented which would give a different position of the studs 12.

[0057] In addition, on each pole of the modules, two studs 12 are obtained, arranged along a diagonal of the entire contact surface of the two plates 10, which better distributes the pressure between the bar 42, 44 and these pole plates by promoting electrical conductivity between them.

[0058] [Fig.6] shows on each end of the module the studs 12 fixed along a diagonal, these two studs being arranged in the transverse direction outside the module. For each long bar 44 connecting two modules, the two diagonals are arranged in the same direction. The pressure is distributed equally well between the bar 42, 44 and the plates 10 of the poles.

[0059] [Fig.7] shows on each end of the module the studs 12 fixed along a diagonal, in the transverse direction one stud being arranged towards the outside of the module and the other towards the inside.

[0060] For each long bar 44 connecting two modules, the two diagonals are arranged in the same direction.

[0061] In the same way, other arrangements can be chosen to avoid the inversion of a cell 2 in the same module, or an inversion of modules, from particular bars 42, 44 adapted to a type of battery to be assembled.

Claims

Claims

1. Method for manufacturing a cell (2) of a traction battery of a motor vehicle, comprising on an upper face (4) two electrical contact pads (6), each pad (6) receiving a screwing device (12) of an electrical connection (42, 44) internal to the battery, characterized in that for each pad (6) it comprises: - a step of fixing by welding using an electric discharge, of the screwing device (12) on the surface of a support (10), forming a connector comprising a particular position of the screwing device (12) on this surface corresponding to a type of battery to be produced, - then a step of fixing the support (10) on the contact pad (6), the screwing device (12) comprising a stud fixed perpendicularly on a plate constituting the support (10).

2. Cell obtained with a manufacturing method according to claim 1, characterized in that the support (10) having a contour corresponding to that of the pad (6), is welded onto this contour by laser welding.

3. Cell according to the preceding claim, characterized in that the studs (6) being arranged at the ends of the upper face (4) of the cell (2) which is elongated along a main axis (A), the screwing devices (12) are, along this main axis (A), positioned on each stud (6) towards the inside or towards the outside of the cell (2).

4. Cell according to any one of claims 2 to 3, characterized in that the studs (6) being arranged at the ends of the upper face (4) of the cell (2) which is elongated along a main axis (A), for each stud (6) the screwing devices (12) are in the transverse direction (B) positioned on one side or the other of the main axis (A).

5. Module comprising two cells (2) according to any one of claims 2 to 4, comprising two pads (6) of the two cells (2) which are connected to each other, characterized in that the positions of the screwing devices (12) on these two pads (6) are different between them.

6.

7.

8. Module according to claim 5, characterized in that the screwing devices (12) of the two studs (6) are arranged along a diagonal of a rectangular surface formed by these two studs (6). Traction battery for an electric or hybrid motor vehicle, characterized in that it comprises modules according to claim 5 or 6. Electric or hybrid motor vehicle equipped with a traction battery comprising cells (2), characterized in that these cells are according to any one of claims 2 to 4.

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