METHOD FOR ASSEMBLING A BATTERY PACK AND ITS JUNCTION BOX

Abstract

The invention relates to an assembly method for assembling a battery pack intended to equip an electric traction vehicle, the battery pack comprising a plurality of electrochemical cell modules, the battery pack comprising a junction box, the method comprising: a- assembling the modules one after the other in a housing, b- assembling a connector (3) on a rear riser wall, c- assembling the junction box onto the connector by moving it from top to bottom (F3) relative to the connector assembly, causing, by means of at least one centering ramp, a realignment of the junction box along the transverse axis (Y), d- screwing in a first screw (V1) and a second screw (V2) to tighten respectively the first and second terminals (51, 52) of the junction box onto the first and second pins (11, 12) of the connector. Figure 2

Description

Title of the invention: METHOD FOR ASSEMBLING A BATTERY PACK AND ITS JUNCTION BOX

[0001] The invention relates to a method for assembling a battery pack intended to equip an electric vehicle. Herein, an electric vehicle is understood to be a vehicle equipped with an electric powertrain capable of moving the vehicle in zero-emission mode.

[0002] Such a battery pack comprises one or more electrochemical cell modules, which makes it possible to ensure a substantial capacity electrical energy storage function.

[0003] Such a battery pack includes at least one power connector which allows a positive pole of the battery pack to be electrically coupled with a positive line of a high-voltage network of the vehicle and a negative pole of the battery pack to be electrically coupled with a negative line of the high-voltage network of the vehicle.

[0004] Such a battery pack includes a junction box which includes isolation contactors allowing the electrical distribution circuit which connects the battery pack to the high voltage network to be opened.

[0005] In practice, there may be two connectors, one at the front of the battery pack and another at the rear of the battery pack. In other configurations, there is only one power connector for the electrical interface.

[0006] The connector passes in a sealed manner through the casing that contains the electrochemical cell modules. The junction box is also housed inside the aforementioned casing.

[0007] The junction box is equipped with two power terminals, i.e., a positive terminal and a negative terminal. Once the battery pack is assembled, the positive terminal of the junction box is electrically connected to the pin of the connector intended to carry the positive voltage from the high-voltage network, and the negative terminal of the junction box is electrically connected to the pin of the connector intended to carry the negative voltage from the high-voltage network.

[0008] The various elements which are contained in the casing of the battery pack are fixed to a lower part of the casing called here 'tray', with a positioning tolerance of a few millimeters.

[0009] Furthermore, the electrical power connections in the battery pack are made by means of busbars which are relatively rigid parts, with little flexibility, which is also the case for the pins of the power connector.

[0010] The present invention is particularly concerned with taking into account the positioning dispersion of the junction box relative to the power connector.

[0011] To accommodate a positioning tolerance along one direction, it is common to use an oblong hole. To accommodate a positioning tolerance along two orthogonal directions, a larger diameter hole than necessary must be used, which reduces the contact area of ​​the screw connection linking one busbar to another, and is detrimental to the quality of the electrical contact.

[0012] The inventors therefore sought to propose an improved solution to take into account positioning dispersions in particular between the junction box and the power connector at the output of the battery pack, with the aim of having a good mutual contact surface between the busbars to be coupled.

[0013] To this end, the present invention proposes an assembly method for assembling a battery pack intended to equip an electric traction vehicle, the battery pack being delimited by a casing enclosing at least one tray, the tray comprising a bottom wall and side walls, the battery pack comprising a plurality of electrochemical cell modules, the battery pack comprising a junction box comprising at least isolation contacts, the battery pack being referenced in space with respect to an orthonormal coordinate system comprising a vertical axis, a longitudinal axis corresponding to a front-to-rear axis of the vehicle, and a transverse axis perpendicular to the vertical and longitudinal axes and corresponding to a left-to-right axis of the vehicle, the method comprising: a- assembling the modules one after the other in the tray, b- assembling, on a rear side wall,a connector assembly comprising a connector support and a connector body; c- assemble the junction box onto the connector assembly, moving it from top to bottom relative to the connector assembly, causing, by means of at least one centering ramp, a realignment of the junction box along the transverse axis relative to the connector assembly; d- screw in a first screw to tighten a first terminal of the junction box onto a first pin of the connector body and screw in a second screw to tighten a second terminal of the junction box onto a second pin of the connector body.

[0014] Thanks to the provisions described above, a dispersion of a few millimeters (up to about ten mm) can be reduced to a positioning within a tolerance of less than 1 millimeter. This allows the size of the hole in the busbars to be limited; their shape can be simply oblong for managing dispersion along the X direction, and reduced to the smallest possible size for the transverse Y direction.

[0015] This ensures good electrical coupling of the junction box with the pins of the connector, with, for each terminal, a substantial contact surface under clamping pressure, for example of at least 1 cm2.

[0016] It is noted that the expression "the tray" covers the case of a single-piece lower shell or the case of a multi-piece tray.

[0017] The junction box may contain, in addition to isolation contactors (for example in the form of relays), fuses, circuits or protective components, without excluding other electrical connection parts.

[0018] It is noted that the junction box is called in the jargon "BDU" from the Anglo-Saxon term "Battery Disconnect Unit" because of one of its functions which is to disconnect the battery from the external voltage network to the battery pack.

[0019] According to one embodiment, the method may further comprise: e- mount busbars connecting the electrochemical cell modules and the junction box, f- to fit a lid onto the container.

[0020] Thanks to these additional steps, the complete assembly of the battery pack is finished.

[0021] According to one embodiment, the centering ramp(s) is / are arranged on the connector assembly. In practice, the centering ramps in question can be provided, according to the most relevant mechanical configuration, on the connector body or on the connector support.

[0022] The connector support, for example, has a shape that flares outwards downwards. The connector support or the connector body may have a conical or pyramidal shape.

[0023] According to one embodiment, the centering ramp(s) is / are arranged on a portion of the junction box facing downwards.

[0024] The junction box can thus include an inverted funnel shape which comes to center itself very naturally on elements of the connector body or the connector support.

[0025] It should be noted that the centering ramps may be present on both the connector assembly side and the junction box side.

[0026] According to a particular example, four centering ramps are provided.

[0027] Depending on whether the offset to be corrected is a movement to the right or a movement to the left, as will be seen later, only half of the centering ramps will be used for recentering.

[0028] According to one embodiment, the first pin of the connector body is longer than the second pin of the connector body, with a length difference of at least 20 mm.

[0029] As a result, although the second spindle is located above the first spindle, access to the screwing area of ​​the first spindle is maintained. The difference in length allows the passage of screwdriver sockets. Furthermore, the screw can be tightened simultaneously on the first and second screws.

[0030] As a specific example, the distance between the screw axes is at least 25 mm, which provides a sufficiently wide passage for the screwdriver sockets

[0031] A person skilled in the art will notice that the connector pins are positioned one above the other along Z, which allows for a flat wiring exit along the transverse direction Y, thanks to the right-angle bend in the power connector. This promotes good integration of the battery pack and its wiring into the vehicle architecture.

[0032] According to one embodiment, the inner end area of ​​the first pin of the connector body includes a first orifice equipped with a first crimped nut, and the inner end area of ​​the second pin of the connector body includes a second orifice equipped with a second crimped nut.

[0033] During tightening, the screw engages with the internal threads of the nut, preventing it from rotating. The crimped nut system allows for very easy assembly by simply inserting and tightening the screw, without requiring access from below.

[0034] According to one embodiment, the first and second orifices are round. This is very simple to manufacture.

[0035] According to one embodiment, an oblong hole is provided in each of the first and second terminals of the junction box to accommodate the dispersion in the longitudinal direction.

[0036] Thanks to these oblong-shaped holes, it is possible to take into account the dispersion present along the longitudinal direction X.

[0037] According to one embodiment, the connector support is made of metal and the connector body is made of plastic.

[0038] According to one embodiment, the connector support is made of aluminum alloy. According to another embodiment, by way of example and not limitation, the connector body is made of polypropylene or polyethylene.

[0039] The invention further relates to a battery pack intended to equip an electric traction vehicle, characterized in that it has been assembled using an assembly process as described above.

[0040] The invention further relates to a vehicle comprising at least one battery pack assembled using an assembly method as described above.

[0041] The invention will be further detailed by describing non-limiting embodiments, and based on the accompanying figures illustrating variants of the invention, in which: [Fig.l] schematically illustrates, in top view, a battery pack intended to equip an electric vehicle; [Fig.2] schematically illustrates, in longitudinal vertical section, the principle of electrical coupling between the terminals of the junction box and the pins of the connector according to an example of an embodiment of the present invention; [Fig.3] schematically illustrates in perspective view the junction box just before its assembly on the connector assembly according to an example of an embodiment of the present invention; [Fig.4] schematically illustrates, in view of vertical cross-section, the principle of Y-alignment provided by the presence of the centering ramps, according to the IV-IV section line indicated in [Fig.2]; [Fig.5] schematically illustrates, in view of vertical cross-section, the principle of Y-alignment provided by the presence of the centering ramps, according to the VV cutting line indicated in [Fig.2] in the final state; [Fig.6] shows, in schematic elevation view, an electric vehicle with the battery pack located in the lower part of the chassis; [Fig.7] schematically illustrates, in top view, the coupling area between the terminals of the junction box and the pins of the connector; [Fig.8] schematically illustrates the assembly movement of the junction box in an XZ plane section.

[0042] In the various figures, the same reference numerals designate identical or similar elements. For the sake of clarity, some elements are not necessarily shown to scale.

[0043] Figure 1 illustrates a PB battery pack, intended to equip an electric vehicle VH shown in Figure 6.

[0044] The vehicle and VH and the battery pack PB are referenced in space with respect to an orthonormal frame comprising a vertical axis Z, a longitudinal axis X corresponding to a front-rear axis of the vehicle, and a transverse axis Y perpendicular to the vertical axis and to the longitudinal axis and corresponding to a left-right axis of the vehicle.

[0045] The power connector and junction box, which will be discussed in more detail below, are located in the rear area of ​​the battery pack. However, it should be noted that the aforementioned elements could just as easily be located in the front area of ​​the battery pack.

[0046] The PB battery pack comprises a plurality of 4 modules, each module comprising a plurality of electrochemical cells.

[0047] The PB battery pack includes an outer casing 10 forming a mechanical protection and delimiting a confined internal space.

[0048] As illustrated in [Fig. 6], the PB battery pack is located in the lower part of the vehicle chassis. In one particular embodiment, the PB battery pack is located under the structural floor of the vehicle VH. It occupies a large portion of the floor area. The battery pack must be protected from the mechanical, physical, and chemical environment, and is therefore encapsulated in the housing, referred to herein as the casing 10. Any ingress of foreign matter that could cause a short circuit must be prevented.

[0049] The battery pack must be replaceable and therefore must be able to be disassembled from the lower chassis structure of the vehicle. The battery is attached to the chassis by means of fastenings which are not shown in the figures in this document.

[0050] According to a particular embodiment, the casing envelope 10 includes a tray 8 and a lid 9.

[0051] The container 8 comprises a bottom wall 7 and upturned edges 6. The container 8 may be a one-piece bottom shell, e.g., a stamped sheet metal piece. Alternatively, the container may be a multi-piece type, e.g., with a bottom and a side rim assembled together. Stiffeners may be provided to support the weight of the modules 4.

[0052] According to an alternative embodiment, the rising walls 6 can be separate pieces assembled on the bottom wall 7.

[0053] The casing 10 is preferably made of metallic material. It forms a hermetic enclosure. The internal volume is configured to receive the plurality of electrochemical cell modules as well as a component of particular interest, namely a junction box 5 with an auxiliary battery management computer, otherwise known in practice as a BMS (Battery Monitoring System).

[0054] The junction box 5 includes two isolation contactors, namely one isolation contactor for interrupting the positive voltage supply line and another isolation contactor for interrupting the negative voltage supply line. In practice, these isolation contactors may take the form of relays. Isolation devices are known in the trade and are therefore not described in detail here.

[0055] The junction box 5 includes an outer casing noted 50 and fixing means 51 for screwing the outer casing onto the bottom wall 7 of the housing envelope 10.

[0056] The junction box may further include one or more fuses and electrical protection circuits. Moreover, the structure and functions of the battery management system (BMS) are known in the trade and are not described here in detail. The battery management system (BMS) controls the opening and closing of the isolation contacts.

[0057] An electrical interface is provided between the PB battery pack and the rest of the vehicle by means of one or two power connectors.

[0058] In the illustrated example, a first power connector is provided in the front area of ​​the battery pack to supply power to the inverter of the electric motor in the front electro-motor unit. Furthermore, a second power connector is provided in the rear area of ​​the battery pack to connect the battery pack to the on-board charger and to manage the charging of the vehicle from a charging station supplying alternating current or direct current in the case of fast charging.

[0059] In the configuration of interest, the junction box 5 is electrically and mechanically coupled directly to a connector assembly noted 3 arranged on the rear portion of the battery pack.

[0060] The connector assembly 3 includes a connector support 2 and a connector body 1.

[0061] The connector support 2 is made of metal, for example aluminum alloy. The connector support is fixed to the tray 8 of the housing 10 by means of fixing screws, only one of which is visible in the figures and is marked 24.

[0062] More precisely, in the illustrated example, the connector support is fixed to the rear riser wall 6 of the housing. It should be noted that the rear riser wall is inclined relative to the vertical. The shape of the connector support 2 compensates for this inclination so that the connector pins are substantially horizontal.

[0063] The connector body 1 is made of plastic, in particular non-conductive plastic. For example, the connector body may be made of polypropylene or polyethylene, but is not limited to these materials. The connector body 1 includes electrical pins.

[0064] In practice, the connector body includes a first power electrical pin 11 and a second power electrical pin 12, and each of them carries the positive or negative voltage of the battery pack.

[0065] The connector passes in a sealed manner through the rising wall 6, i.e. passes through the casing; a portion of the connector is inside the casing and another portion is outside the casing to receive a wiring plug 82.

[0066] The free outer end of the first pin 11 is designated 61 as illustrated in [Fig. 3]. Here it is in the form of a pin with a cylindrical cross-section, but it could have another shape. Similarly, the free outer end of the second pin 12 is designated 62.

[0067] As illustrated in figures 1 and 2, the power connector 1 is configured to receive by coupling a power plug 82 containing two conductors and two clips adapted to each plug onto the outer end 61, 62 of the power connector 1. The electrical conductors form a 90° bend in the power plug 82.

[0068] It should be noted that the power wiring harness 83 connected to the power connector 82 has a path at the rear of the battery pack that is generally parallel to the Y direction. This facilitates the integration of the battery pack PB and its associated wiring into the vehicle architecture. This also explains the arrangement of the pins of connector 11, 12 one above the other.

[0069] Turning to [Fig.2], we notice that the first pin 11 of the connector body is longer than the second pin 12 of the connector body, with a difference in length noted DI.

[0070] In practice, a value of at least 20 mm is chosen for the distance DI.

[0071] This offset allows access, from above, i.e. along the Z direction, the end area of ​​the first pin on the inside, despite the presence of the second pin which is located above the first pin, but set back.

[0072] A screwdriver can thus be passed to screw or unscrew the screw marked V1 which allows the first pin 11 to be mechanically coupled with the first terminal 51 of the junction box 5.

[0073] A screwdriver socket can also be used to screw or unscrew the screw VL

[0074] The screw marked V2 allows the second pin 12 to be mechanically coupled with the second terminal 52 of the junction box 5.

[0075] The first pin is spaced from the second pin along the vertical Z direction by a second distance denoted D2, determined by the standard for the two-way power connector. D2 can typically range from 15 mm to 30 mm, without these values ​​being limiting.

[0076] As can be seen from Figures 2 and 7, the first pin 11 includes an orifice marked TL. Preferably, this is a round orifice. Similarly, the second pin 12 includes an orifice marked T2. Preferably, this is a round orifice.

[0077] In the illustrated example, the first and second pins are formed as a flat bar. Other shapes, including a round section, are also possible, provided that the end area where holes T1 and T2 are drilled is crushed and flattened.

[0078] The first orifice T1 has an axis Al and the second orifice T2 has an axis A2. The axes Al and A2 are substantially parallel to the vertical axis Z, they are spaced by the aforementioned distance DI.

[0079] The junction box 5 includes a first terminal 51 intended to be electrically coupled to the first pin 11 of the connector and includes a second terminal 52 intended to be coupled to the second pin 12 of the connector 1.

[0080] The first terminal 51 covers the first pin 11 and the second terminal 51 covers the second pin 12.

[0081] The junction box 5 includes an access well 59 which allows a tool to reach the screw head VI, both for initial tightening and for possible subsequent disassembly. Depending on the geometric configuration, there may also be a shallower well for accessing the second screw V2.

[0082] In the coupling zone, the first terminal 51 includes an oblong hole T3, visible in particular in [Fig. 7], the second terminal 52 includes an oblong hole T4. The long dimension of these oblong holes is parallel to X.

[0083] The oblong shape of these holes allows for a dispersion of positioning of the junction box 5 relative to the connector along the longitudinal direction X.

[0084] Advantageously, according to the present invention, the possible dispersion of positioning of the junction box along the transverse axis Y is canceled by the effect of the centering ramps 26.

[0085] Indeed, when the junction box 5 is assembled on the connector assembly, by moving it from top to bottom F3, this causes, thanks to the centering ramps, a realignment / recentering of the junction box along the transverse axis Y with respect to the connector assembly.

[0086] In the illustrated example, the centering ramp(s) 26 are symmetrical and are arranged on the connector assembly.

[0087] In the illustrated example, the centering ramps 26 are part of walls 22. Two walls 22 are provided on either side of the connector pins.

[0088] On either side of the pins. Expressed in other words, the pins of the connector are interposed along Y between the two walls 22, which are symmetrical in the illustrated example.

[0089] As can be seen in the figures, the section of the wall decreases as it goes up, the wall acts as a corner.

[0090] In the illustrated example, there are also centering ramps 56 on a portion of the junction box's mounting. Here too, they are symmetrical with respect to the axis of the screwing to be carried out.

[0091] The centering ramps 56 are attached to an external wall 57, these shapes being obtained from plastic molding.

[0092] The centering ramps 56 of the junction box are arranged in an interior area of ​​a portion of the mouth denoted 58. The centering ramps 56 form an inverted V, open downwards as seen in figures 3, 4 and 5.

[0093] According to one embodiment, the centering means could be offset to one side, away from the pin area. There could be a pyramid on the connector side and an inverted V or funnel shape on the junction box side.

[0094] According to other configurations, the centering ramps could only be present on the connector part or only on the junction box part.

[0095] It is noted that it is not excluded to have a single centering ramp, starting from a position always off-center on the same side.

[0096] The inner end area of ​​the first pin 11 of the connector body includes a first orifice T1 equipped with a first crimped nut 91, and the inner end area of ​​the second pin 12 of the connector body includes a second orifice T2 equipped with a second crimped nut 92.

[0097] The nuts 91 92 may include a sleeve extension to present enough internal threads and support screwing with substantial torque.

[0098] The crimped nut system allows for very easy assembly by bringing the screw in and screwing it in, without needing access from below.

[0099] It should be noted here that the screws can be pre-positioned in an elastomer skirt (not shown in the figures). The initial assembly and subsequent maintenance operations are thus made simpler and more reliable.

[0100] To reformulate the entire assembly process, the following actions are planned to be carried out.

[0101] a- assemble the modules 4 one after the other in the tray 8, along X and fixed on the bottom 7.

[0102] b- assemble, on the rear rising wall 6, the connector assembly 3 comprising the connector support 2 and the connector body 1.

[0103] It is noted that steps a- and - can be carried out in any order.

[0104] The process continues as follows: c- assemble the junction box 5 onto the connector assembly, moving it from top to bottom F3 relative to the connector assembly, causing, thanks to the centering ramps (26,56), a realignment of the junction box along the transverse axis Y relative to the connector assembly,

[0105] d- screw the first screw V1 to tighten a first terminal 51 of the junction box onto the first pin 11 and screw the second screw V2 to tighten the second terminal 52 of the junction box onto a second pin 12.

[0106] e- mounting busbars 43 connecting modules 4 and junction box 5, which causes junction box 5 to become electrically energized,

[0107] f- mount the lid 9 onto the tray and fix them together using fasteners 98.

[0108] Considering [Fig.5], we see that the angle of inclination [31 of the ramp 26 on the wall 22 can be between 15° and 30°.

[0109] Similarly, we see that the angle of inclination [32 of the ramp 56 on the mouth of the junction box can be between 15° and 30°.

Claims

Demands

1. Assembly method for assembling a battery pack (PB) intended to equip an electric traction vehicle, the battery pack being delimited by a casing (10) with at least one tray (8), the tray comprising a bottom wall (7) and side walls (6), the battery pack comprising a plurality of electrochemical cell modules (4), the battery pack comprising a junction box (5) comprising at least isolation contacts, the battery pack being referenced in space with respect to an orthonormal coordinate system comprising a vertical axis (Z), a longitudinal axis (X) corresponding to a front-to-rear axis of the vehicle, and a transverse axis (Y) perpendicular to the vertical and longitudinal axes and corresponding to a left-to-right axis of the vehicle, the method comprising: a- assembling the modules one after the other in the tray, b- assembling, on a rear side wall,a connector assembly (3) comprising a connector support (2) and a connector body (1), c- assemble the junction box onto the connector assembly, moving it from top to bottom (F3) relative to the connector assembly, causing, by means of at least one centering ramp (26,56), a realignment of the junction box along the transverse axis (Y) relative to the connector assembly, d- screw in a first screw (VI) to tighten a first terminal (51) of the junction box onto a first pin (11) of the connector body and screw in a second screw (V2) to tighten a second terminal (52) of the junction box onto a second pin (12) of the connector body.

2. Assembly method according to claim 1, further comprising: e- mounting bus bars connecting the electrochemical cell modules (4) and the junction box, f- mounting a cover (9) on the tray (8).

3. Assembly method according to claim 1, characterized in that the centering ramp(s) is / are arranged on the connector assembly (3).

4. Assembly method according to claim 1, characterized in that the centering ramp(s) is / are arranged on a portion of the junction box facing downwards.

5. Assembly method according to any one of claims 1 to 4, characterized in that the first pin (11) of the connector body is longer than the second pin (12) of the connector body, with a difference in length (Dl) of at least 20 mm.

6. Assembly method according to any one of claims 1 to 5, characterized in that an inner end zone of the first pin (11) of the connector body comprises a first orifice (T1) equipped with a first crimped nut (91), and an inner end zone of the second pin (12) of the connector body comprises a second orifice (T2) equipped with a second crimped nut (92).

7. A method according to any one of claims 1 to 6, characterized in that an oblong hole (T3,T4) is provided in each of the first and second terminals (51,52) of the junction box to accommodate the dispersion along the longitudinal direction (X).

8. A method according to any one of claims 1 to 7, characterized in that the connector support (2) is made of metal and the connector body (1) is made of plastic.

9. Battery pack (PB) intended to equip an electric traction vehicle, characterized in that it has been assembled using an assembly process according to any one of claims 1 to 8.

10. Motor vehicle (MV) comprising a battery pack assembled using an assembly method according to any one of claims 1 to 8.

Images