Busbar for storage battery, mechatronic connection box, storage battery pack and motor vehicle including such a busbar

Abstract

The invention relates to a busbar (37) adapted to provide an electrical connection between at least two electrical components of a battery. According to the invention, the busbar comprises a stack of at least three electrically conductive, elongated strips (370), each strip being in contact with at least one other strip along a first portion (372) of its length and separated from said strip along a second portion (373) of its length. Figure for the abstract: Fig. 3

Description

Title of the invention: Busbar for battery pack, mechatronic connection box, battery pack and motor vehicle comprising such a busbar. Technical field of the invention

[0001] The present invention relates generally to the cooling of electrical devices.

[0002] It relates more particularly to a mechatronic connection box for a battery of accumulators, a battery of accumulators equipped with such a box and a motor vehicle equipped with such a battery of accumulators. State of the art

[0003] Electric or hybrid motor vehicles are equipped with a battery pack comprising a casing which houses several electrochemical cells connected together and providing a high voltage at the battery terminals, typically a voltage of several hundred volts.

[0004] It is then necessary to equip the battery with a mechatronic connection box including, in particular, electrical safety components (relays, fuses) in order to regulate and cut off the current as needed. These electrical components are connected to each other by metallic and electrically conductive busbars, through which the current flowing into or out of the battery circulates.

[0005] In certain situations, the battery receives or supplies a high electrical power. This is the case, for example, during so-called fast charging of the vehicle's battery, or when the vehicle must exert significant traction. In these situations, the flow of a high-intensity current, which can exceed 500A, generates a sharp increase in the battery's temperature, particularly within the mechatronic connection box.

[0006] Certain areas of the housing are specifically prone to experiencing particularly high temperature increases compared to surrounding areas; these areas are conventionally referred to as "hot spots," and are located, for example, at the contacts between the safety electrical components and the busbar. Thus, components located at hot spots are at an increased risk of degradation due to temperature.

[0007] To protect these components, localized cooling solutions exist, specifically targeting potential hot spots. For example, a hollow busbar housing a plurality of conduits was proposed in document EP0407167A2. A refrigerant circulates within these conduits and contributes to cooling the busbar.

[0008] However, since the maximum permissible current flowing through a busbar depends on its cross-sectional area, it is important to maximize this area in mechatronic junction boxes that may be subjected to high currents. In the specific context of components for electric or hybrid vehicles, it is also necessary to minimize the volume occupied by the busbar due to the limited space available in these boxes. Therefore, the solution proposed here is not optimal with respect to this constraint on the ratio between the volume and the cross-sectional area of ​​the busbar. Presentation of the invention

[0009] In order to remedy the aforementioned drawback of the prior art, the present invention proposes to locally cool the housing at the hot spots, while optimizing the maximum permissible current in the housing as well as the volume of the latter.

[0010] More specifically, the invention proposes a busbar adapted to provide an electrical connection between at least two electrical components equipping a battery of accumulators as defined in the introduction, wherein a stack of at least three electrically conductive and elongated strips is provided. Each strip is in contact with at least one other strip along a first part of its length and separated from said at least one other strip along a second part of its length.

[0011] Thus, thanks to the invention, with the same conductive cross-section and therefore the same maximum permissible current as a busbar of identical length, but where the strips are in contact with each other along their entire length, the available heat exchange surface, which corresponds to the sum of the surfaces in contact with the ambient space, is multiplied in the second part. This multiplication of the available surface area promotes heat exchange with the ambient space and contributes to cooling the hot spots in contact with the busbar.

[0012] In addition, the use of the omnibus bar according to the present invention as a cooling element makes it possible to advantageously limit the weight and size of the mechatronic connection box.

[0013] Other advantageous and non-limiting features of the omnibus bar according to the invention, taken individually or in all technically possible combinations, are as follows: - The second parts of the slats, designed to promote heat exchange, are all located on the same portion of the length of the omnibus bar. - Two means of fixing the omnibus bar to the two electrical components are provided; these fixing means are located on the first parts of the lengths of the slats. - The second parts are located between the two means of attachment. - The second parts each consist of two distinct sections, located on either side of the fastening means. - The fastening means include holes passing through the stack of slats.

[0014] The invention also proposes a mechatronic connection box for the battery pack comprising: - A support plate with an upper surface that supports electrical components and, - at least one busbar as described in the invention, which provides the electrical connection between at least two of said electrical components.

[0015] This mechatronic connection box can also be advantageously adapted for use with busbars as described in the invention, by allowing their cooling on their second sections by forced convection. For this purpose, the support plate of the mechatronic connection box defines a passageway for a heat transfer fluid which opens to the outside through at least one outlet located at the second sections of the lengths of the busbar's slats, and a means is provided to force the heat transfer fluid through the passageway to said outlet.

[0016] The invention also proposes a battery of accumulators for motor vehicles comprising electrochemical cells and at least one mechatronic connection box according to the invention.

[0017] Finally, the invention also proposes a motor vehicle comprising a battery of accumulators according to the invention.

[0018] Preferably, a computer is provided located at a distance from the battery of accumulators and the forcing means is electrically controlled by said computer.

[0019] Of course, the different features, variants and embodiments of the invention can be combined with each other in various ways insofar as they are not incompatible or mutually exclusive. Detailed description of the invention

[0020] The following description with regard to the attached drawings, given by way of non-limiting examples, will make it clear what the invention consists of and how it can be carried out.

[0021] On the attached drawings:

[0022] [Fig-1] is a schematic view of a motor vehicle according to the invention, equipped of a battery of accumulators equipped with a mechatronic connection box;

[0023] [Fig.2] represents a schematic view of part of the mechatronic connection box of the [Fig.1];

[0024] [Fig.3] schematically represents an exploded view and an assembled view of an omnibus bar of the mechatronic connection box of the [Fig.1];

[0025] [Fig.4] are schematic views of four variant embodiments of the omnibus bar of [Fig.3];

[0026] [Fig.5] is a schematic view of another variant embodiment of the omnibus bar of [Fig.3];

[0027] [Fig.6] is a schematic cross-sectional view of a support plate for the mechatronic connection box of [Fig.2].

[0028] Figure 1 schematically represents an electric or hybrid motor vehicle 1. This vehicle has a traction system 2, at least partially powered by a battery 3, and a charging system 4 for said battery 3.

[0029] The latter comprises a plurality of accumulator cells connected together to deliver at its terminals a required voltage that can vary between ten and several hundred volts, in particular 400V, or even 800V. It further comprises at least one mechatronic connection box 30, the function of which is to regulate or even cut off the flow of electric current between its terminals if necessary.

[0030] As illustrated in [Fig.2], the mechatronic connection box 30 is a system which includes: - a support plate 33, - electrical components 34, 35, 36 fixed on the support plate 33, and - several bus bars 37 which provide an electrical connection in series from an input terminal 31 to an output terminal 32, via the electrical components 34, 35, 36 and which allow the localized cooling of the hot spots located at the point of contact with the bus bars and the aforementioned electrical components.

[0031] The support plate 33 is generally parallelepiped-shaped, with two main faces, namely an upper face 331 and a lower face 332. For simplicity, this support plate 33 will be considered to be installed horizontally within the vehicle, so that its upper face 331 extends horizontally. In the remainder of this description, the mechatronic connection box 30 will be described in this particular orientation.

[0032] Here, the support plate 33 is, for example, made of a polymer material, such as acrylonitrile butadiene styrene (ABS). The support plate 33 can, in particular, be obtained by a molding process (typically by extrusion).

[0033] The electrical components 34, 35, 36, as well as the bus bars 37 which provide the electrical connection between these components, are arranged on the upper face 331 of the support plate 33.

[0034] Here, the electrical components 34, 35, 36 and the bus bars 37 linking them electrically are placed side by side along a horizontal axis H1.

[0035] The electrical components 34, 35, 36 are configured to interrupt the flow of electrical current within the mechatronic connection box 30 when necessary. For example, the electrical components include a switch 34, an electromechanical relay 35, and a fuse 36.

[0036] The switch 34 is here a pyrotechnic safety switch (“pyroswitch”, according to the Anglo-Saxon designation) and is configured to quickly cut off the electrical flow in the event of an accident of the motor vehicle 1. It is for example activated by a sensor of the motor vehicle 1, for example an impact sensor.

[0037] The electromechanical relay 35 is configured to, during normal use of the vehicle, reversibly cut off the flow of electric current between the terminals of the mechatronic connection box 30. It is, for example, controlled by a driver of the motor vehicle 1, to stop or operate the traction system 2 of the vehicle.

[0038] Fuse 36 is configured to cut off the flow of electric current when it is too high, which is the case for example in the event of a short circuit.

[0039] The electrical connection between these electrical components is ensured by the bus bars 37, as is the mechanical connection.

[0040] The electrical components 34, 35, 36 can be fixed to the support plate 33 in various ways.

[0041] Typically, the electrical components 34, 35, 36 are screwed onto the upper face 331 of the support plate 33.

[0042] For example, the electromechanical relay 35 has two mounting fins at its base, positioned in contact with the upper face 331 of the support plate 33. Each Each of the two mounting fins has a hole drilled through it, through which a screw can be inserted. Two threaded bores corresponding to the pitch and dimension of the screw are drilled in the upper face 331 of the support plate 33, in order to allow the electromechanical relay 35 to be fixed.

[0043] The switch 34 and the fuse 36 are fixed by means of two metal tabs, located on either side of the switch and the fuse, along the horizontal axis H1. Each of these metal tabs has an opening through which a fixing screw 38 is inserted.

[0044] In this example, mounting brackets 333 are raised to protrude from the upper face 331 of the support plate 33, in order to accommodate the switch 34 and the fuse 36. These mounting brackets 333 are each drilled with a tapped bore into which one of the fixing screws 38 is screwed.

[0045] The support plate 33 then carries two mounting supports 333 on each side of the terminals of the switch 34 and the fuse 36. It also has two more at each of its ends, at the input terminal 31 and the output terminal 32.

[0046] One of the busbars 37 extends from one of the mounting brackets 333 located at the input terminal 31 to another of the mounting brackets 333 located at the first terminal of the fuse 36. A second busbar 37 extends from the second mounting bracket 333 bordering the second terminal of the fuse 36 to one of the terminals of the electromechanical relay 35. A third busbar then extends from the second terminal of the electromechanical relay 35 to one of the mounting brackets associated with the switch 34. Finally, a last busbar extends from the second mounting bracket associated with the switch 34 to the mounting bracket 333 of the output terminal 32.

[0047] These omnibus bars 37 preferably have substantially identical shapes.

[0048] They are configured to be traversed by high-intensity electric currents, which can in particular reach up to 500A or even 1000A during a fast charging phase of the accumulator battery 3 by the charging system 4, or during the traction of the vehicle by the traction system 2.

[0049] These high electric current values ​​cause an increase in temperature on the bus bars 37, and can cause hot spots, typically located at the contact between the electrical components 34, 35, 36 and said bus bars 37. It is then necessary to cool these hot spots, otherwise the electrical components 34, 35, 36 will be damaged.

[0050] The configuration of each busbar 37 is illustrated in [Fig. 3]. According to the invention, the busbar advantageously allows the heat generated within it to be dissipated, and consequently reduces the temperature of the hot spots at its proximity, while optimizing the ratio between the conductive section and the volume of each bus bar 37.

[0051] To this end, each omnibus bar 37 has a stack of at least three thin strips 370.

[0052] Each slat 370 is in the form of an elongated metal plate, having two main faces.

[0053] Here, since the electrical components 34, 35, 36 are placed along the length of the support plate 33, in the direction of the horizontal axis Hl, the slats 370 are elongated along this same horizontal axis Hl.

[0054] Each slat 370 is then oriented so that its main faces follow a vertical axis, perpendicular to the upper face 331 of the support plate 33.

[0055] Finally, each slat 370 of the stack, or at least a part of them, is folded or curved in the horizontal plane materialized by the horizontal axis H1 and a horizontal x-axis also perpendicular to H1. The "length" of a slat 370 will therefore be defined curvilinearly, in this horizontal plane.

[0056] The slats 370 are obtained by bending or stamping sheets from copper coils, for example, in order to obtain the desired geometry for the omnibus bar 37.

[0057] The slats 370 are stacked one on top of the other by their principal faces, along the horizontal x-axis.

[0058] The number of slats 370 in the stack can be chosen according to the cooling requirements generated by the hot spots.

[0059] Their thickness along the x-axis and the number of slats in the stack can be selected according to the conductive section required for current conduction.

[0060] According to one possible embodiment, an omnibus bar 37 can be made up of four slats 370 of 0.5mm thickness each.

[0061] The slats 370 are electrically conductive and made of metal, such as copper or aluminum for example.

[0062] In practice, the slats 370 of the same omnibus bar 37 are folded or bent in the horizontal plane with different amplitudes or in different sections along their lengths.

[0063] Thus, once stacked, they are in contact with each other over only a portion of their lengths. This first portion will be designated by the numerical reference 372.

[0064] The slats 370, however, separate from each other over a second part of their length. This second part will be designated by the numerical reference 373.

[0065] In other words, the slats 370 are curved or folded in such a way that an empty space remains between them once these slats are stacked.

[0066] Here we can define the notion of "available surface" of an omnibus bar as the sum of the surfaces of the slats 370 which are in direct contact with the ambient air.

[0067] In the first part 372 of their lengths, where the different lamellae 370 of the stack are in contact with each other, only two of the main surfaces of the lamellae contribute to the available surface. One of these main surfaces belongs to the lamella 370 located at the beginning of the stack, the second main surface belongs to the lamella 370 located at the end of the stack.

[0068] On the second part 373 of their lengths however, since an empty space remains between each of the slats 370 forming the omnibus bar, the two main surfaces included on this second part 373 of each of the slats 370 contribute to the available surface.

[0069] Increasing the available surface area on this second part 373 of the busbars 37 allows for increased heat exchange between them and a heat transfer fluid suitable for dissipating heat by convection, preferably towards the outside of the connection box. Here, this heat transfer fluid is air.

[0070] According to one possible embodiment of the present invention, heat exchange can be done with the ambient air of the mechatronic connection box 30.

[0071] According to another embodiment described later, heat exchange can be done with air forced into circulation in the mechatronic connection box 30, by a fan or a compressor.

[0072] In order to secure the bus bars 37 and the electrical connection between the input terminal 31 and the output terminal 32 via the electrical components 34, 35, 36, two fastening means 374 are provided on each of the bus bars 37. These fastening means 374 are placed on the first part 372 of the length of the slats 370, where these are in contact with each other.

[0073] Here, each fastening means 374 takes the form of a hole passing through the stack of slats 370, through which the corresponding fastening screw 38 can pass. Thus, the fastening screws 38 not only allow some of the electrical components 34, 36 to be fixed to the support plate 33 via the mounting brackets 333, but also allow the bus bars 37 to be connected to these electrical components 34 and 36.

[0074] In this example, the electromechanical relay 35 includes two tapped holes into which the fixing screws 38 are screwed, to allow the electrical connection between the electromechanical relay 35 and the bus bars 37 as well as its mechanical fixing to them.

[0075] Here, each fastening means 374 allows both the busbar 37 and the various electrical components 34, 35, 36 to be electrically connected, but also to keep the different slats 370 of the stack in contact in the first part 372 of their lengths.

[0076] Alternatively, the different strips 370 could be fixed together, for example by gluing or welding at the level of their first parts 372.

[0077] Clamping collars can also be provided around the first parts 372 of the slats 370, in order to keep them in contact, and thus facilitate their assembly.

[0078] An infinite number of geometric variations are possible for the busbars 37; these are not limited to the embodiments shown in the figures. The choice of geometry used can be made according to the arrangement of the electrical components 34, 35, 36 on the support plate 33 of the mechatronic connection box 30.

[0079] In a first, more compact embodiment, the slats 370 are in contact with each other at their ends and are separated from each other in their central part. In other words, the first parts 372 of the slats 370 of the busbar 37 each comprise two portions 372A and 372B located at the ends of the busbar 37, at which the fastening means 374, here holes, are located.

[0080] According to this first embodiment illustrated in [Fig.3], the omnibus bar has an S shape. Each of the slats 370 has successively along its length a first flat section, followed by a section curved in a quarter circle in one direction, followed by a section curved in a quarter circle in the opposite direction and a second flat section.

[0081] The lamellae 370 are in contact with each other at the level of their flat sections, which therefore constitute the first parts 372.

[0082] These flat sections have lengths that vary from one slat 370 to another, so that these slats 370 move apart from each other at their curved sections. Heat exchange therefore occurs at the curved sections; these are thus the second parts 373.

[0083] Possible geometry variants for this first embodiment of the omnibus bars are illustrated in [Fig.4].

[0084] In [Fig. 4] (a), the lamellae 370 are not progressively curved along arcs of circles as shown in [Fig. 3]. On the contrary, in this variant, each lamella 370 has two right-angled bends. These bends are not located in the same place from one lamella to the next, so that the sections of the lamellae 370 located between these bends are separated in pairs, thus maintaining a gap between the lamellae 370 for heat exchange.

[0085] A second variant is illustrated in [Fig. 4] (b). According to this variant, the omnibus bar has a top hat shape. One of the slats is thus perfectly flat, while the others each have a first flat section, followed by a rectangular notch and a second flat section located in the extension of the first. Each rectangular notch has three intermediate flat sections folded into a U shape. The height of the notch varies from one slat to another, in order to leave a gap between the different slats 370 at the notched section, while the slats 370 remain in contact with each other at the first flat section, as well as at the second flat section.

[0086] A third variant is illustrated in [Fig. 4] (c). According to this embodiment, the busbar 37 describes a U-shape. The stacking slats 370 comprise a first flat section, followed by a semicircular curved section, and a second flat section parallel to the first. The length of the sections is adjusted to leave a gap between each slat 370 at the arc of the circle to form the second part 373.

[0087] A fourth variant is illustrated in [Fig. 4] (d). This variant is similar to the U-shaped variant described previously. However, the curved section is replaced by a flat intermediate section connected to the first and second sections by two right-angled folds. Here again, the length of the sections is adjusted to space the slats 370 from each other so as to form the second part 373.

[0088] A second embodiment of the omnibus bar is illustrated in [Fig. 5]. In this second embodiment, the omnibus bar 37 consists, for example, of a stack of five slats 370.

[0089] This second mode differs from the first in that the lamellae are in contact with each other by their central parts, and they move apart from each other at the level of at least one of their ends (here at the level of their two ends).

[0090] In other words, the second parts 373 of the slats 370 of the omnibus bar 37 comprise two end portions 373A and 373B, located on either side of the screw receiving holes which constitute the fixing means 374.

[0091] According to this embodiment, the busbar 37 comprises a perfectly flat slat 370. The other slats 370 in the stack have a first flat section, followed by a rectangular notch, followed by a second flat section extending from the first. Each rectangular notch comprises three intermediate sections, folded into a U-shape. The slats 370 are brought into contact with each other on the central section of the rectangular notch. The height of the notches varies between each slat 370, so that the slats 370 are separated from each other at the first and second flat sections.

[0092] In other words, the bus bars 37 thus obtained have cooling fins located at their ends, while allowing two electrical components 34, 35, 36 to be connected on its central part.

[0093] These examples of embodiments and variants illustrate the multiple forms that the geometry of the omnibus bar can take according to the invention described, but are by no means intended to be exhaustive and are in no way limiting.

[0094] Fig. 6 illustrates a possible embodiment for a support plate 33 advantageously adapted to the use of omnibus bars 37 according to the present invention, by promoting heat exchange by forced convection.

[0095] In the cross-sectional view of [Fig.6], the support plate 33 is hollow so that it delimits a passage channel 334.

[0096] Within this passage duct 334, the heat transfer fluid can circulate.

[0097] For this purpose, the passage duct 334 opens to the outside through at least one inlet and at least one outlet 335.

[0098] It is thus provided at least one outlet 335 opening onto the upper face 331 of the support plate 33 and allowing the heat transfer fluid to circulate at the level of the second part 373 of the omnibus bars 37, in order to promote the cooling of the latter by forced convection.

[0099] In practice, an exit 335 is provided under each omnibus bar 37.

[0100] Here, the outlet openings 335 are rectangular cutouts. For example, the outlet openings 335 may have been molded with the rest of the support plate 33.

[0101] The outlet mouths 335 have dimensions adapted to those of the second part 373 of the omnibus bars 37, in order to benefit from an optimized exchange surface.

[0102] The inlet opening also has a rectangular cut-out shape made in the support plate 33.

[0103] A forcing means 336 adapted to circulate the heat transfer fluid through the passage duct 334 to the outlet vents 335 can also be integrated.

[0104] Here, for example, the forcing means 336 can be an air blower, or an air compressor placed on the inlet. Air can thus flow from the forcing means 336 to one of the outlets 335 via the passage duct 334.

[0105] The battery of accumulators 3 includes an integrated computer, generally designated by the English acronym BMS (for "battery management system").

[0106] The motor vehicle 1, which carries this battery of accumulators 3 (and therefore the mechatronic connection box 30), also includes an on-board computer 5, located remotely from the battery (see [Fig. 1]). This on-board computer can electrically control various elements of the motor vehicle, in response to sensors.

[0107] Preferably, it will be the on-board computer 5 that will be able to activate, as needed, the means for forcing the heat transfer fluid of the connection box mechatronics 30, for example when the charging system 4 is active, or when a sensor detects an excessively high temperature inside the housing.

[0108] The present invention is in no way limited to the embodiments described and represented, but a person skilled in the art will be able to make any variation in accordance with the invention.

[0109] Typically, it could be foreseen that the slats are in contact with each other only at the level of their screw receiving holes, but that they move apart from each other not only between these holes but also on either side of these holes (on the side of their ends).

[0110] According to another variant, it could be provided that in the same omnibus bar, two slats move apart from each other in the central part and that two other slats move apart from each other at one of their ends.

Claims

Demands

1. Mechatronic connection housing (30) for a battery pack (3), comprising: - a support plate (33) having an upper face (331) which supports electrical components (34, 35, 36), and - at least one bus bar (37) adapted to provide an electrical connection between at least two electrical components (34, 35, 36) equipping a battery pack (3), said at least one bus bar (37) comprising a stack of at least three electrically conductive and elongated strips (370), each strip (370) being in contact with at least one other strip (370) over a first part (372) of its length and separated from said at least one other strip (370) over a second part (373) of its length,said mechatronic connection box (30) being characterized in that said support plate (33) delimits a passage conduit (334) for a heat transfer fluid which opens to the outside through at least one outlet (335) located at the level of the second parts (373) of the lengths of the slats of said busbar (37), and in which a forcing means (336) adapted to circulate a heat transfer fluid in the passage conduit (334) to said outlet (335) is provided....,

2. Mechatronic connection box (30) according to claim 1, wherein the second parts (373) of the slats (370) of said at least one bus bar (37) are all located on the same portion of the length of the bus bar.

3. Mechatronic connection box (30) according to claim 1 or 2, wherein two means are provided for fixing the bus bar (37) to the two electrical components (34, 35, 36) respectively, which are located on the first parts (372) of the lengths of the slats (370).

4. Mechatronic connection housing (30) according to claim 3, wherein the second parts (373) are located between the two fastening means (374).

5. Mechatronic connection housing (30) according to claim 3, wherein the second parts (373) each comprise two distinct sections located on either side of the two fastening means (374).

6. Mechatronic connection housing (30) according to any one of claims 3 to 5, wherein the fastening means (374) have holes through the stack of slats (370).

7. Battery of accumulators (3) for motor vehicle (1) comprising electrochemical cells and at least one mechatronic connection box (30) according to any one of claims 1 to 6.

8. Motor vehicle (1) comprising at least one battery of accumulators (3) according to claim 7.

9. Motor vehicle (1) according to claim 8, wherein a computer (5) is provided located at a distance from the battery of accumulators (3) and wherein the forcing means (336) is electrically controlled by said computer (5).

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