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 equipping 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: Bus bar for storage battery, mechatronic connection box, storage battery block and motor vehicle comprising such a bus bar 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 storage battery, a storage battery equipped with such a box and a motor vehicle equipped with such a storage battery. State of the art

[0003] Electric or hybrid motor vehicles are equipped with a storage battery comprising a housing which houses several electrochemical cells connected together and providing a high voltage to the terminals of the battery, 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 (relay, fuse) in order to regulate and cut off the current as needed. These electrical components are connected to each other by metallic and electrically conductive bus bars, in which the current entering or leaving the battery circulates.

[0005] In certain situations, the battery receives or supplies high electrical power. This is the case, for example, during so-called rapid recharges of the vehicle battery, or when the vehicle must provide significant tractive effort. In these situations, the circulation of a high intensity current, which may exceed 500A, generates a significant increase in the temperature of the battery, particularly within the mechatronic connection box.

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

[0007] In order to preserve these components, there are local cooling solutions- calibrated, specifically targeting potential hot spots. For example, in document EP0407167A2, a hollow busbar model housing a plurality of conduits has been proposed. A refrigerant fluid circulates within these conduits and contributes to the cooling of the busbar.

[0008] However, since the maximum permissible current that can flow in a bus bar depends on its conductive section, it is important to maximize this in mechatronic connection boxes likely to be faced with high currents. In the particular context of components dedicated to an electric or hybrid motor vehicle, it is also necessary to minimize the volume occupied by the bus bar, due to the limited space available in these boxes. The solution proposed here is therefore not optimal in the face of this constraint on the ratio between volume and conductive section of the bus bar. Presentation of the invention

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

[0010] More particularly, the invention proposes a bus bar adapted to provide an electrical connection between at least two electrical components equipping a storage battery as defined in the introduction, in which a stack of at least three electrically conductive strips of elongated shape is provided. Each strip is in contact with at least one other strip over a first part of its length and spaced from said at least one other strip over a second part of its length.

[0011] Thus, thanks to the invention, with a conductive section and therefore with an equal maximum admissible current compared to a bus bar of identical length, but where the strips would be in contact with each other over their entire lengths, the available heat exchange surface, which corresponds to the sum of the surfaces in contact with the ambient space, is multiplied at the level of the second parts. This multiplication of the available surface makes it possible to promote heat exchanges with the ambient space and contributes to cooling the hot points in contact with the bus bar.

[0012] Furthermore, the use of the bus 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 characteristics of the bus bar according to the invention, taken individually or in any technical combinations- only possible, are as follows: - The second parts of the slats, intended to promote thermal exchanges, are all located on the same portion of the length of the bus bar. - Two means of fixing the bus bar to the two electrical components are provided, these fixing means are located on the first parts of the lengths of the strips. - The second parts are located between the two fixing means. - The second parts each comprise two separate sections, located on either side of the fixing means. - The fixing means comprise holes passing through the stack of slats.

[0014] The invention also provides a mechatronic connection box for the accumulator battery pack comprising: - A support plate having an upper face which supports electrical components and, - at least one bus bar 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 to the use of bus bars as described in the invention, by allowing cooling of these on their second parts by forced convection. For this, the support plate of the mechatronic connection box delimits a passage conduit for a heat transfer fluid which opens outwards via at least one outlet located at the level of the second parts of the lengths of the strips of said bus bar, and a forcing means is provided adapted to circulate a heat transfer fluid in the passage conduit to said outlet.

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

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

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

[0019] Of course, the various features, variants and embodiments of the invention may be combined with each other in various combinations to the extent that they are not incompatible or mutually exclusive. Detailed description of the invention

[0020] The description which follows with reference to the attached drawings, given as examples non-limiting, will make it clear what the invention consists of and how it can be implemented.

[0021] In the attached drawings:

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

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

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

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

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

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

[0028] In [Fig.l], an electric or hybrid motor vehicle 1 is schematically represented. This has a traction system 2, at least partially powered by a storage battery 3 and a charging system 4 for said storage battery 3.

[0029] The latter comprises a plurality of accumulator cells connected together to deliver to its terminals a required voltage which 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 comprises: - a support plate 33, - electrical components 34, 35, 36 fixed on the support plate 33, and - several bus bars 37 which provide a series electrical connection from an input terminal 31 to an output terminal 32, passing through the electrical components 34, 35, 36 and which allow localized cooling of the hot spots located at the level of contact with the bus bars and the aforementioned electrical components.

[0031] The support plate 33 here has a general parallelepiped shape, with two main faces, namely an upper face 331 and a lower face 332. For simplification, it will be considered that this support plate 33 is installed horizontally within the vehicle, so that its upper face 331 itself extends to horizontal. In the remainder of this presentation, it is in this particular orientation that the mechatronic connection box 30 will be described.

[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 electrically connecting them are placed next to each other along a horizontal axis H1.

[0035] The electrical components 34, 35, 36 are configured to cut off the flow of electric 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 English term) and is configured to quickly cut off the electrical flow in the event of an accident to the motor vehicle 1. It is for example actuated 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 activate the traction system 2 of the vehicle.

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

[0039] The electrical connection between these electrical components is provided 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 fixing fins at its base, placed in contact with the upper face 331 of the support plate 33. Each of the two fixing fins is pierced with a hole, through which a screw can be engaged. Two tapped bores corresponding to the pitch and the dimension of the screw are drilled in the upper face 331 of the support plate 33, in order to allow the fixing of the electromechanical relay 35.

[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. These metal tabs are each pierced with an opening, through which a fixing screw 38 is engaged.

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

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

[0046] One of the bus bars 37 thus extends from one of these fixing supports 333 located at the input terminal 31 to another of the fixing supports 333 located at the first terminal of the fuse 36. A second bus bar 37 extends from the second fixing support 333 bordering the second terminal of the fuse 36 to one of the terminals of the electromechanical relay 35. A third bus bar then extends from the second terminal of the electromechanical relay 35 to one of the fixing supports associated with the switch 34. Finally, a last bus bar extends from the second fixing support associated with the switch 34 to the fixing support 333 of the output terminal 32.

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

[0048] They are configured to be crossed by electric currents of significant intensity, which can in particular go up to 500A or even 1000A during a rapid 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 values ​​of electric current cause an increase in the temperature on the bus bars 37, and can be the cause of 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 bus bar 37 is illustrated in [Fig. 3]. According to the invention, the bus bar advantageously allows the evacuation of the heat generated therein, and consequently the reduction of the temperature of the hot spots in its vicinity, while optimizing the ratio between the conductive section and the volume of each bus bar 37.

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

[0052] Each strip 370 is in the form of an elongated metal plate, provided with 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 H1, the strips 370 are elongated along this same horizontal axis H1.

[0054] Each strip 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 strip 370 of the stack, or at least a portion of them, is folded or curved in the horizontal plane materialized by the horizontal axis H1 and an axis x also horizontal, and perpendicular to H1. The “length” of a strip 370 will therefore be defined in a curvilinear manner, in this horizontal plane.

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

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

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

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

[0060] According to a possible embodiment, a bus bar 37 may consist of four strips 370 each 0.5 mm thick.

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

[0062] In practice, the strips 370 of the same bus bar 37 are folded or curved 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 part of their lengths. This first part will be designated by the numerical reference 372.

[0064] The slats 370, on the other hand, move away from each other over a second part of their lengths. 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 a bus bar as the sum of the surfaces of the strips 370 which are in direct contact with the ambient air.

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

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

[0069] The increase in the surface area available on this second part 373 of the bus bars 37 makes it possible to increase the heat exchanges between them and a heat transfer fluid adapted to evacuate the heat by convection, preferably towards the outside of the connection box. Here, this heat transfer fluid is air.

[0070] According to a possible embodiment of the present invention, the heat exchanges can be made with the ambient air of the mechatronic connection box 30.

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

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

[0073] Here, each fixing means 374 takes the form of a hole passing through the stack of slats 370, into which the corresponding fixing screw 38 can pass. Thus, the fixing screws 38 not only make it possible to fix certain of the electrical components 34, 36 to the support plate 33 via the fixing supports 333, but also to connect the bus bars 37 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 fixing means 374 makes it possible both to bring the bus bar 37 and the various electrical components 34, 35, 36 into electrical contact, but also to maintain the various strips 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 their first parts 372.

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

[0078] An infinite number of geometric variants are possible for the bus bars 37, these are not limited to the embodiments shown in the figures. The choice of the 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, most compact embodiment, the strips 370 are in contact with each other at their ends, and move apart from each other in their central part. In other words, the first parts 372 of the strips 370 of the bus bar 37 each comprise two portions 372A and 372B located at the ends of the bus bar 37, at the level of which the fixing means 374 are located, here holes.

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

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

[0082] These flat sections have lengths which vary from one strip 370 to another, so that these strips 370 move apart from each other at their curved sections. The heat exchanges therefore take place at the curved sections, these are therefore the second parts 373.

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

[0084] In [Fig.4] (a), the slats 370 are not progressively curved in arcs of circles as shown in [Fig.3]. On the contrary, in this variant, each slat 370 has two right-angled bends. These bends are not located in the same place from one slat to the other, so that the sections of the slats 370 located between these bends are spaced apart two by two, so as to maintain an empty space between the slats 370 for heat exchange.

[0085] A second variant is illustrated in [Fig.4] (b). According to this variant, the bus bar has a top hat shape. One of the strips 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. The height of the notch is variable from one strip to another, in order to leave an empty space between the different strips 370 at the level of the section in notch, while the slats 370 remain in contact with each other at the level of the first flat section, as well as at the level of the second flat section.

[0086] A third variant is illustrated in [Fig.4] (c). According to this variant of the embodiment, the bus bar 37 describes a U shape. The strips 370 of the stack comprise a first flat section, followed by a section curved in a semicircle, and a second flat section parallel to the first. The length of the sections is adjusted so as to leave an empty space between each strip 370 at the level of 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 bends. Here again, the length of the sections is adjusted to space the slats 370 apart from each other so as to form the second part 373.

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

[0089] This second mode is distinguished from the first in that the slats are in contact with each other by their central parts, and they move away from each other at at least one of their ends (here at both ends).

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

[0091] According to this embodiment, the bus bar 37 comprises a strip 370 left perfectly flat. The other strips 370 of the stack have a first flat section, followed by a rectangular notch followed by a second flat section in the extension of the first. Each rectangular notch has three intermediate sections, folded into a U. The strips 370 are brought into contact with each other on the central section of the rectangular notch. The height of the notches varies between each strip 370, so that the strips 370 move apart from each other at the level of the first and second flat sections.

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

[0093] These examples of embodiments and variants make it possible to account for the multiple forms that the geometry of the bus bar according to the invention described can take, but are in no way 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 the bus bars 37 according to the present invention, in promoting heat exchange by forced convection.

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

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

[0097] For this, the passage conduit 334 opens outwards via at least one inlet opening and at least one outlet opening 335.

[0098] At least one outlet 335 is thus provided 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 bus bars 37, in order to promote the cooling of the latter by forced convection.

[0099] In practice, an outlet 335 is provided under each bus bar 37.

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

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

[0102] The inlet mouth also has a rectangular cutout shape made in the support plate 33.

[0103] A forcing means 336 adapted to circulate the heat transfer fluid through the passage conduit 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 mouth. The air can thus circulate from the forcing means 336, to one of the outlet mouths 335 via the passage duct 334.

[0105] The accumulator battery 3 comprises an integrated computer, generally designated by the English acronym BMS (for “battery management System”).

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

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

[0108] The present invention is in no way limited to the embodiments described and shown, but those skilled in the art will be able to provide any variant in accordance with the invention.

[0109] Typically, it could be provided that the slats are in contact with each other only at 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 bus bar, two strips move away from each other in the central part and that two other strips move away from each other at one of their ends.

Claims

Claims

1. Bus bar (37) adapted to provide an electrical connection between at least two electrical components (34, 35, 36) equipping a storage battery (3), characterized in that it comprises a stack of at least three electrically conductive strips (370) of elongated shape, each strip (370) being in contact with at least one other strip (370) over a first part (372) of its length and spaced from said at least one other strip (370) over a second part (373) of its length.

2. The bus bar (37) of claim 1, wherein the second portions (373) of the strips (370) are all located on a same portion of the length of the bus bar.

3. Bus bar (37) according to claim 1 or 2, wherein there are provided two means (374) for fixing the bus bar (37) to the respective two electrical components (34, 35, 36), which are located on the first parts (372) of the lengths of the strips (370).

4. A bus bar (37) according to claim 3, wherein the second portions (373) are located between the two fixing means (374).

5. Bus bar (37) according to claim 3, in which the second parts (373) each comprise two separate sections located on either side of the two fixing means (374).

6. Bus bar (37) according to one of claims 3 to 5, in which the fixing means (374) comprise holes passing through the stack of strips (370).

7. Mechatronic connection box (30) for an accumulator 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) according to one of claims 1 to 6, which provides the electrical connection between at least two of said electrical components.

8. Mechatronic connection box (30) according to claim 7, in which the support plate (33) delimits a passage conduit (334) for a heat transfer fluid which opens outwards through at least one outlet opening (335) located at the level of the second parts (373) of the lengths of the strips of said bus bar (37), and in which there is provided a forcing means (336) adapted to circulate a heat transfer fluid carrier in the passage conduit (334) to said outlet mouth (335).

9. Accumulator battery (3) for a motor vehicle (1) comprising electrochemical cells and at least one mechatronic connection box (30) according to one of claims 7 or 8.

10. Motor vehicle (1) comprising at least one accumulator battery (3) according to claim 9.

11. Motor vehicle (1) according to claim 10, the mechatronic connection box (30) of which is in accordance with claim 8, in which a computer (5) is provided, located at a distance from the accumulator battery (3) and in which the forcing means (336) is electrically controlled by said computer (5).

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