Motor vehicle comprising a device for cooling at least one electric accumulator

Abstract

The invention relates to a motor vehicle comprising at least one electric accumulator and a cooling device (10) for said at least one electric accumulator, said cooling device comprising a transport circuit (12) for a cooling fluid comprising: - a fluid supply duct (18) in fluid communication with the fluid inlet, - a fluid outlet duct (24) formed in the extension of the fluid supply duct and being in fluid communication with the fluid outlet, said supply and outlet ducts extending respectively along a first (22) and a second (28) path parallel to each other, each supply section being in contact with a fluid outlet section, each pair of sections being in contact with at least one other pair of sections so as to allow a heat exchange between at least two pairs of sections. Figure for the abstract: Fig. 3

Description

Title of the invention: Motor vehicle comprising a device for cooling at least one electric accumulator

[0001] The present invention relates to the automotive field, in particular to electrically powered vehicles.

[0002] In particular, the present invention relates to a motor vehicle comprising a device for cooling at least one electric accumulator.

[0003] For optimal operation of an electric accumulator, it is important to maintain the temperature of this electric accumulator within a predetermined temperature range. During operation of an electrically powered motor vehicle, the temperature of the electric accumulators exceeds an optimal temperature range, which requires cooling these electric accumulators.

[0004] It is known to cool electric accumulators by means of a cooling device integrated into the casing of the electric accumulators. These cooling devices comprise a cooling liquid circuit making it possible to carry out a heat exchange between cells or modules located inside the electric accumulators and the cooling liquid in order to reduce the temperature of the electric accumulators.

[0005] The coolant enters an electric accumulator, heats up as it receives heat from the cells or modules, and exits the electric accumulator at another end of the circuit. The temperature difference dT of the coolant between its entry into the electric accumulator and its exit may be, for example, 5 or 10°C. Depending on where the cells or modules are located in relation to the path of the coolant circuit, the cells are therefore cooled by a more or less hot coolant.For example, if the coolant enters the electric accumulator at a temperature of 30°C and dT is 6°C (related to the total heat flow generated by the cells), the cells located at the coolant inlet are cooled with a liquid at 30°C, while those located at the circuit outlet are cooled with liquid at 36°C. The cells located towards the circuit outlet therefore have a higher operating temperature than the cells located towards the circuit inlet, for example 6°C in the previous example.

[0006] The cells of electric accumulators have a maximum operating temperature limit. The electronic management system (called BMS for “Battery Management System” in English) of electric accumulators can limit the performance of electric accumulators to avoid exceeding this maximum operating temperature limit. However, this limitation of performance is generally carried out based on the cell with the highest operating temperature (typically the one cooled by the hottest coolant, towards the outlet). Thus, even if the majority of cells have an operating temperature lower than the maximum operating temperature limit, a restriction of the performance of the accumulators can occur while the majority of cells are at an acceptable operating temperature.

[0007] The difference in operating temperature depending on the position of the cells is also detrimental because it causes cell-to-cell performance differences that must be addressed via the BMS. In particular, cells discharge differently depending on their operating temperature. It is therefore necessary to take this difference into account when recharging them. In addition, cells operating at different temperatures may have durability differences depending on the position of the cell in question. Again, it is the cell that ages the fastest that defines the durability of the entire electric accumulator pack.

[0008] Patent application DE102019201127 describes a cooling device for homogenizing the temperature in a battery, by arranging in the base of its casing a cooling duct with several sections arranged so as to couple incoming sections and outgoing sections of the duct. But this solution is very complex to implement, requiring in particular a large quantity of duct sections independent of each other, as well as a large quantity of hoses of very varied shapes, in order to connect the different duct sections together. Ultimately, this solution is expensive and unreliable.

[0009] There is therefore a need for a motor vehicle having a cooling device allowing more homogeneous operation of the cells of the electric accumulators, in particular in terms of performance, simplicity of management, durability and reliability.

[0010] For this, the invention proposes a motor vehicle comprising at least one electric accumulator and a device for cooling said at least one electric accumulator, said cooling device comprising a circuit for transporting a cooling fluid comprising: - a fluid inlet and an outlet, - a fluid supply conduit in fluid communication with the fluid inlet, the fluid supply conduit being formed by a plurality of fluid supply sections, - a fluid outlet conduit formed in the extension of the fluid supply conduit and being in fluid communication with the fluid outlet so as to form a cooling fluid circulation loop between the fluid inlet and outlet, the fluid outlet conduit being formed by a plurality of fluid outlet sections, said supply and outlet conduits extending respectively along a first and a second path parallel to each other, each supply section being in contact with a fluid outlet section so as to allow a heat exchange between the cooling fluid present in the supply section and the cooling fluid present in the outlet section, the transport circuit defining a plurality of pairs of sections, a pair of sections comprising a supply section and an output section in contact with each other, wherein the transport conduit is shaped such that each pair of sections is in contact with at least one other pair of sections so as to allow heat exchange between at least two pairs of sections.

[0011] The cooling fluid transport circuit is produced with a double heat exchange interface: a first between the supply duct (i.e. "outgoing" duct) and the outlet duct (i.e. "return" duct) and a second between pairs of sections of these supply and outlet ducts. Thus, a double homogenization of the temperature of the cooling fluid occurs. This makes it possible to obtain a quasi-constant temperature at the level of the cells of the electric accumulators regardless of the position of the cells relative to the cooling device.

[0012] It is thus possible to increase the performance of electric accumulators, to simplify their management and finally to increase their durability.

[0013] According to one embodiment of the motor vehicle, the first and second trajectories are shaped so that each pair of sections extends parallel to at least one adjacent pair of sections.

[0014] According to one embodiment of the motor vehicle, each pair of sections comprises at least one wall common with an adjacent pair of sections.

[0015] According to one embodiment of the motor vehicle, the transport circuit forms a coil with adjoining segments, said coil comprising an open end formed by the fluid inlet and outlet and a closed end formed by a junction between the supply and outlet conduits.

[0016] According to one embodiment of the motor vehicle, the transport circuit is shaped so that the heat flow received by the fluid present in the supply duct between the fluid inlet and a junction point between the supply and outlet ducts is equal to the heat flow received by the fluid present in the outlet duct between the junction point between the supply and outlet ducts and the fluid outlet.

[0017] According to one embodiment of the motor vehicle, the cooling device comprises a receiving surface extending above each of the pairs of sections so as to form a receiving floor for said at least one electric accumulator.

[0018] According to one embodiment of the motor vehicle, the supply and outlet pipes are made of a single piece, for example in the form of a serpentine.

[0019] According to one embodiment of the motor vehicle, the supply and outlet pipes are of rectangular section.

[0020] According to one embodiment of the motor vehicle, the latter comprises a plurality of electrical accumulators extending along a first direction and arranged parallel to one another, the pairs of sections of the cooling device extending along a second direction perpendicular to the first direction, each electrical accumulator being in contact with at least two pairs of sections.

[0021] According to one embodiment of the motor vehicle, the latter further comprises a motorization device configured to move the motor vehicle, said at least one accumulator being configured to supply electrical energy to said motorization device. Brief description of the drawings

[0022] The accompanying drawings illustrate the invention:

[0023] [Fig-1] represents a schematic top view of a cooling device of at least one electric accumulator comprising a circuit for transporting a cooling fluid.

[0024] [Fig.2] represents a schematic cross-sectional view of the cooling device of [Fig.l].

[0025] [Fig.3] represents a schematic top view of the cooling device of [Fig.l] with a plurality of electric accumulator cells placed on a transport circuit of said cooling device.

[0026] [Fig.4] represents a schematic view in longitudinal section of the cooling device of [Fig.l] with an electric accumulator cell arranged on said cooling device. Description of embodiment(s)

[0027] The concept of the invention is described more fully below with reference to the accompanying drawings, in which embodiments of the concept of the invention are shown. In the drawings, the size and relative sizes of the elements may be exaggerated for the sake of clarity. Like numbers refer to like elements throughout the drawings. However, this concept of the invention may be put implemented in many different forms and should not be construed as being limited to the embodiments set forth herein. Instead, these embodiments are provided so that this description is complete, and communicates the scope of the inventive concept to those skilled in the art.

[0028] A reference throughout the specification to "an embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrase "in an embodiment" at various locations throughout the specification does not necessarily refer to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. Furthermore, the term "comprising" does not exclude other elements or steps.

[0029] The present invention is illustrated with the aid of figures which show an example of a cooling device for a motor vehicle. This cooling device can be integrated into an electric accumulator housing or else produced in the form of a cooling floor on which one or more electric accumulators can be arranged.

[0030] With reference to [Fig.l], a cooling device 10 for at least one electric accumulator is proposed. This electric accumulator is for example an accumulator configured to supply electrical energy to a motorization device of the motor vehicle. In other words, said at least one electric accumulator is preferably a battery pack powering the electric vehicle, in particular for its movement.

[0031] The cooling device comprises a transport circuit 12 for a cooling fluid. This transport circuit 12 comprises a fluid inlet 14 and an outlet 16. These fluid inlets 14 and outlets 16 are connected to a circuit portion for setting the cooling fluid in motion. The transport circuit 12 forms a half-loop in which the cooling fluid is set in motion to cool an accumulator arranged on said cooling device 10. Thus, the transport circuit extends between a first open end at the fluid inlets 14 and outlets 16 and a second closed end 15 corresponding to a midpoint 0 of the transport circuit 12.

[0032] The cooling fluid may be glycolated water, air or a refrigerant fluid such as an air conditioning fluid.

[0033] The transport circuit 12 comprises a fluid supply conduit 18 forming a “forward” portion of the transport circuit up to the midpoint 0. The supply conduit 18 is in fluid communication with the fluid inlet 14. The conduit supply 18 is formed by a plurality of fluid supply sections 20. Each supply section 20 corresponds to a segment of the supply conduit 20 when the latter has a change of orientation. The supply conduit 20 extends along a first trajectory 22.

[0034] The transport circuit 12 also comprises a fluid outlet conduit 24 forming a “return” portion of the transport circuit 12 from the midpoint 0. The outlet conduit 24 is formed in the extension of the supply conduit 18 and in fluid communication with the fluid outlet 16. Thus, the supply 18 and outlet 24 conduits form a portion of an open loop for circulating cooling fluid between the fluid inlet 14 and outlet 16. This open loop is preferably part of a closed loop in which a means for circulating the fluid is installed. This circulation means is for example a circulation pump. The outlet conduit 24 is formed by a plurality of fluid outlet sections 26. Each outlet section 26 corresponds to a segment of the outlet conduit 24 when the latter has a change of orientation. The outlet conduit 24 extends along a second trajectory 28.

[0035] The first 22 and second 28 trajectories are parallel to each other so as to follow each other from the inlet 14 and outlet 16 to the midpoint 0. The points Me and ms are arranged respectively on a longitudinal axis of the supply 18 and outlet 24 conduits at the level of the inlet 14 and outlet 16. The supply 18 and outlet 24 conduits are shaped so that the distance separating Me and 0 is equal to the distance separating Ms and 0. Thus, the lengths of the supply 18 and outlet 24 conduits are equal.

[0036] Each supply section 20 is in contact with a fluid outlet section 26 so as to allow a heat exchange between the cooling fluid present in the supply section 20 and the cooling fluid present in the outlet section 26. A first temperature homogenization can therefore take place between the supply 18 and outlet 24 conduits.

[0037] The transport circuit 12 defines a plurality of pairs of sections 30. Each pair of sections 30 comprises a supply section 20 and an outlet section 26 in contact with each other. In other words, a pair of sections is formed by two adjacent supply 20 and outlet 26 sections. Each pair of sections 30 corresponds to a segment of the supply 18 and outlet 24 conduits when these have a change of orientation.

[0038] The transport conduit 12 is shaped such that each pair of sections 30 is in contact with at least one other pair of sections. Thus, it is possible to carry out a heat exchange between at least two adjacent pairs of sections. Depending on the pair of sections considered, it may be in contact with two pairs of adjacent sections, i.e. the one preceding it and the one following it. A second temperature homogenization therefore takes place, this time between pairs of adjacent sections 30. This makes it possible to obtain a small temperature difference of the cooling fluid between the fluid inlet 14 and outlet 16. The performance of the electric accumulator cooled by the cooling device can therefore be improved, its management simplified and its durability improved.

[0039] To improve the heat exchange between the supply 18 and outlet 24 conduits, a single conduit wall 25 is preferably arranged between the supply 18 and outlet 24 conduits of the same pair of sections 30. In other words, a single conduit wall 25 separates the supply 18 and outlet 24 conduits.

[0040] Similarly, a single pair wall 27 is preferably disposed between two adjacent pairs of sections 30 to further improve the heat exchange. Thus, each pair of sections 30 has a pair wall 27 in common with an adjacent pair of sections 30. Thus, the transport circuit 12 preferably forms a coil with adjoining segments, the coil comprising the supply 18 and outlet 24 conduits. By coil is meant the fact that the supply 18 and outlet 24 conduits are S-shaped (a single S or a plurality of successive Ss) and that they are nested one inside the other.

[0041] The first 22 and second 28 trajectories may be shaped such that each pair of sections 30 extends parallel to at least one adjacent pair of sections.

[0042] With reference to [Fig.2], a cross-section of the transport circuit 12 along points Pe and Ps is shown. Ps is the projection of Pe in the outlet conduit 24 onto the perpendicular to the direction of flow of the cooling fluid.

[0043] The supply ducts 18 and outlet ducts 24 may be of square or rectangular section.

[0044] The supply 18 and outlet 24 pipes can be made from a single piece.

[0045] The supply 18 and outlet 24 conduits are preferably made of a material having a thermal conductivity greater than or equal to 100 W m-1 Kl, preferably greater than 160 W m-1 KL. This material is for example copper or aluminum.

[0046] To further improve the homogenization of the temperature of the cooling fluid, the transport circuit 12 can be shaped so that the heat flux received by the fluid present in the supply conduit 18 between the fluid inlet 14 and the midpoint 0 is equal to the heat flux received by the fluid present in the outlet conduit 24 between the midpoint 0 and the fluid outlet 16. For this, the distance separating Me and Pe must be equal to the distance separating Ms and Ps. Me, Pe, Ms and Ps are taken on the longitudinal axis along which each of the supply 18 and outlet 24 conduits extend. Furthermore, this equality is obtained by considering the heat flux sent by the cells or modules is homogeneous over the entire surface covered by the transport circuit 12.

[0047] The preferred arrangement of the electric accumulator cells is illustrated in [Fig. 3]. The cells 32 extend along a first direction 34 and are arranged parallel to each other. The pairs of sections 30 of the cooling device 10 extend along a second direction 36 perpendicular to the first direction 34. Each cell 32 is in contact with at least two pairs of sections 30. Preferably, each cell 32 is in contact with all of the pairs of sections 30.

[0048] Reference 32 may represent a cell or an accumulator module comprising a plurality of cells.

[0049] In this arrangement, the average of the temperatures of the cooling fluid at points Pe and Ps is constant throughout the path of the fluid. We therefore have the same value regardless of the position of point Pe and its projection Ps. In other words, (T°Pe+T°Ps) / 2 = constant between the inlet and the outlet of the fluid.

[0050] It is also noted that (T°Pe+T°Ps) / 2 = constant = (T°Me+T°Ms) / 2, with T°Me and T°Ms the temperature of the fluid at points Me and Ms. In other words, the transport circuit 12 is shaped so that the average temperature between points Pe and Ps or between points Me and Ms is almost constant throughout the transport circuit 12.

[0051] In reality, the equality “(T°Pe+T°Ps) / 2 = constant” may not be perfectly fulfilled, given that there may be disparities in the local heat flow, due to the fact that the heat flow from the cells 32 will depend on the local temperature of the fluid. Thus, it will be considered that the difference at any point of the transport circuit 12 is less than or equal to 3°C, preferably less than or equal to 2°C.

[0052] When referring to the temperature of the cells 32, we consider the apparent temperature seen at the base of the cells 32 located closest to the cooling device 10.

[0053] [Fig. 4] shows a longitudinal sectional view (for example along the second direction 36) of the cooling device 10 with a cell 32 of an electric accumulator arranged above the transport circuit 12. The cell 32 is arranged on a lower wall 38 of an accumulator module. Thermal paste 40 may be arranged between the cell 32 and the lower wall 38. The cooling fluid 42 may then be surrounded by casing walls 44. Thermal paste 40 may also be arranged between a wall of the casing 44 and the lower wall 38.

[0054] The juxtaposition of the supply 18 and outlet 24 conduits can locally create a temperature disparity when a pair of sections 30 is not in contact with two pairs of sections 30. However, this disparity is not or is barely perceived at the level of the cells 32 due to the different thicknesses separating the cells 32 from the cooling fluid 42. Indeed, the cells are not in direct contact with the cooling fluid 42. These thicknesses constitute as many transverse thermal resistances attenuating this disparity. These thermal resistances, combined with the thermal conduction of these different thicknesses in the longitudinal direction, make it possible to homogenize the temperatures at the level of the fluid. The cells 32 therefore only see an apparent temperature corresponding on average to (T°Pe+T °Ps) / 2 = constant because the different thermal resistances between the fluid and the foot of the cells create a temperature gradient.

[0055] The cooling device 10 may comprise a plurality of transport circuits 12 mounted next to each other to cover a larger surface area.

Claims

Claims

1. Motor vehicle comprising at least one electric accumulator and a cooling device (10) for said at least one electric accumulator, said cooling device comprising a transport circuit (12) for a cooling fluid comprising: - a fluid inlet (14) and an outlet (16), - a fluid supply conduit (18) in fluid communication with the fluid inlet, the fluid supply conduit being formed by a plurality of fluid supply sections (20), - a fluid outlet conduit (24) formed in the extension of the fluid supply conduit and being in fluid communication with the fluid outlet so as to form a cooling fluid circulation loop between the fluid inlet and the fluid outlet, the fluid outlet conduit being formed by a plurality of fluid outlet sections (26),said supply and outlet conduits extending respectively along a first (22) and a second (28) path parallel to each other, each supply section being in contact with a fluid outlet section so as to allow a heat exchange between the cooling fluid present in the supply section and the cooling fluid present in the outlet section, the transport circuit (12) defining a plurality of pairs of sections (30), a pair of sections comprising a supply section and an outlet section in contact with each other, in which the transport circuit is shaped in such a way that each pair of sections is in contact with at least one other pair of sections so as to allow a heat exchange between at least two pairs of sections, the lengths of the supply (18) and outlet (24) conduits being equal.,

2. A motor vehicle according to claim 1, wherein the first (22) and second (28) trajectories are shaped such that each pair of sections (30) extends parallel to at least one adjacent pair of sections.

3. Motor vehicle according to claim 1 or 2, in which each pair of sections (30) comprises at least one wall (27) common with an adjacent pair of sections.

4. Motor vehicle according to one of claims 1 to 3, in which the transport circuit forms a coil with joined segments, said coil comprising an open end formed by the fluid inlet (14) and outlet (16) and a closed end formed by a junction between the supply and outlet conduits.

5. A motor vehicle according to any one of the preceding claims, wherein the transport circuit (12) is shaped so that the heat flux received by the fluid present in the supply duct between the fluid inlet and a junction point between the supply and outlet ducts is equal to the heat flux received by the fluid present in the outlet duct between the junction point between the supply and outlet ducts and the fluid outlet.

6. Motor vehicle according to any one of the preceding claims, in which the cooling device comprises a receiving surface extending above each of the pairs of sections so as to form a receiving floor for said at least one electric accumulator.

7. Motor vehicle according to any one of the preceding claims, in which the supply (18) and outlet (24) pipes are made from a single piece.

8. A motor vehicle according to any one of the preceding claims, wherein the supply and outlet pipes are of rectangular or square section.

9. A motor vehicle according to any preceding claim, comprising a plurality of electrical accumulators extending along a first direction and arranged parallel to each other, the pairs of sections of the cooling device extending along a second direction perpendicular to the first direction, each electrical accumulator being in contact with at least two pairs of sections.

10. Motor vehicle according to any one of the preceding claims, further comprising a motorization device configured to move the motor vehicle, said at least one accumulator being configured to supply electrical energy to said motorization device.

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