IT201900005738A1 - BATTERY PACK ELEMENT WITH AN EMPTY SPACE BETWEEN BATTERY CELLS TO CHANNEL A HALF HEATER - Google Patents

Description

DESCRIPTION

of the patent for industrial invention entitled:

"BATTERY PACK ELEMENT WITH AN EMPTY SPACE BETWEEN BATTERY CELLS TO CHANNEL A HALF HEATER"

TECHNICAL FIELD

The present invention relates to a battery pack element, which is provided with an empty space between battery cells, to channel a heat transfer medium inside a corresponding battery pack, in particular for an electric vehicle propulsion system.

BACKGROUND OF THE INVENTION

In electric vehicles, it is generally known to provide at least one battery or battery pack, which operates at relatively high voltages (for example, 400 or 800 V) and is cooled / heated by a heat transfer medium, in such a way as to maintain it at a temperature range capable of guaranteeing optimal operation of the propulsion system. By way of example, the temperature of the battery pack is controlled in such a way as to be between about 15 and 40 ° C.

In some solutions of the prior art, the heat transfer medium is channeled inside the battery pack in such a way as to flow between the battery cells of the pack, and therefore obtain greater uniformity in the heating / cooling of these battery cells.

It is considered necessary to improve this type of solutions, for example to optimize the cooling / heating of the battery cells, and / or to increase the amount of heat transferred, and / or to decrease the thermal gradient between the battery cells. In practice, these improvements are necessary to install higher power batteries in electric vehicles, to achieve a longer useful life of these batteries, to ensure a continuous power demand and / or to improve the accuracy of estimates relating to so-called "state of charge" ”(SoC, State-of-Charge) and“ State-of-Health ”(SoH) of the battery pack.

An object of the present invention is to satisfy the aforementioned need in a simple and economical way.

SUMMARY OF THE INVENTION

The aforementioned object is achieved by a battery pack element, as defined in claim 1, and a thermal management system, as defined in claim 13.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, for a better understanding of the present invention, a preferred embodiment is described by way of non-limiting example, with reference to the attached drawings, in which:

Figure 1 is a diagram schematically showing a thermal management system with a battery pack which includes a preferred embodiment of the battery pack element provided with a gap between the battery cells, for channeling a heat transfer medium, according to the present invention;

• Figure 2 is a perspective view showing a detail of the battery pack element of the present invention, on an enlarged scale and with parts removed for clarity purposes;

Figure 3 is a schematic side view of the detail in figure 2;

Figures 4 and 6 are similar to figure 2 and show respective variants of the detail in figures 2 and 3;

Figures 5 and 7 are similar to figure 3 and show other variants of the detail in figures 2 and 3; And

• Figures 8 and 9 are front views showing other variants of the detail in Figures 2 and 3. DETAILED DESCRIPTION OF THE INVENTION

Figure 1 schematically shows some parts of an electric propulsion vehicle, indicated as a whole by the reference number 1. The vehicle 1 can be a purely electric propulsion vehicle, or a hybrid propulsion vehicle equipped with at least one electric motor and an engine internal combustion (not shown).

The vehicle 1 comprises a battery pack 2, in particular of the so-called "high voltage" type (for example, 48 V or 400 V or 800 V), which accumulates and supplies electrical energy, such as direct current. The vehicle 1 also comprises an electric heater 7 and an air conditioning system 8 to heat and cool the air in a passenger compartment (not shown). In particular, the system 8 includes a compressor 9, a condenser 10 and an evaporator 11, used to cool the air in the passenger compartment.

The system 8 also includes an exchanger called "cooling device" ("chiller") and indicated by the reference number 12, for the heat exchange between the cooling liquid of the system 8 and a heat transfer medium (for example: water , oil, mixture of water and glycol, etc.), which flows into a thermal management system 14 adapted to regulate the temperature of the battery pack. In particular, the cooling device 12 is arranged parallel to the evaporator 11. By way of example, the condenser 10 is of the air-cooled type, for example it is arranged in a frontal area of the vehicle 1 and is cooled by a flow of ambient air, external to the vehicle 1, possibly by means of forced ventilation, or by operating a fan 13.

On the other hand, the system 14 includes a closed circuit 15 and a pump 17 arranged along the closed circuit 15 to feed the heat carrier medium. The system 14 also comprises the cooling device 12 and the heating device 20 arranged along the closed circuit 15, respectively to cool and heat the heat transfer medium. Preferably, the cooling device 12 and the evaporator 11 are associated with valves equipped with closing systems or electronic regulating systems, respectively, controlled by an electronic control unit (not shown) to regulate the flow of coolant in the two branches of the system 8, which are respectively dedicated to the air conditioning of the passenger compartment and to the cooling of the heat transfer medium in the circuit 15. In particular, the cooling in the cooling device 12 is activated / used when the battery pack 2 has a higher temperature than at a first predetermined threshold (for example, 40 ° C), so that the heat transfer medium in the circuit 15 is cooled and can remove the heat from the battery pack 2.

Preferably, the heating device 20 is controlled by the electronic control unit to heat the heat transfer medium when the temperature of the battery pack 2 is below a second predetermined threshold (for example, 0 ° C). According to a variant (not shown), the heating device 20 is integrated inside the battery pack 2.

The battery pack 2 comprises an external casing 21 provided with at least one inlet mouth 22 and at least one outlet mouth 23 connected to the closed circuit 15, to allow the heat transfer medium to flow in and out.

The battery pack 2 comprises a plurality of battery pack elements, of which only one is schematically and partially shown in Figure 2.

Each battery pack element comprises a plurality of battery cells, arranged in such a way as to form two parallel layers, which are spaced apart along a transverse direction 28. The battery cells of these layers are indicated respectively by the reference numbers 29a and 29b. In particular, the battery pack 2 comprises a greater number of parallel layers of cells, spaced apart, as partially shown in Figure 3.

In particular, each of the aforementioned layers is defined by a single row of battery cells, aligned along a corresponding direction 30 orthogonal to direction 28.

There is an empty space 31 between the battery cells 29a provided in one layer and the battery cells 29b provided in the adjacent and facing layer. The empty space 31 defines a single plane passage, which channels a flow of the heat transfer medium, along a longitudinal direction 32, from an inlet area 33 to an outlet area 34, respectively provided to let the heat transfer medium flow into and outside the empty space 31. The passage defined by the empty space 31 is continuous along a direction transverse to the directions 28 and 32, ie it is not divided into separate channels or separate flows.

The longitudinal direction 32 of the empty space 31 is orthogonal to the direction 28 and, in this embodiment of Figures 2 and 3, also to the direction 30.

Preferably, the inlet area 33 and the outlet area 34 comprise respective manifolds 35 and 36 (shown schematically in Figure 3), which are arranged inside the casing 21 at the opposite longitudinal ends of the battery pack elements and are in communication, respectively, with the mouths 22 and 23 (in a way which is not shown).

Referring to Figure 2, the battery cells 29a, 29b have respective side surfaces or edges 40 which are transverse to the direction 30 and, in each layer, are in contact with each other, preferably in a fluid-tight manner, so that each cell layer is continuous along the direction 30. Furthermore, each cell layer has two heat exchange surfaces 41 (Figure 3), which are opposite along the direction 28 and delimit the respective empty spaces 31. In other words, along the surfaces 41, the heat is exchanged between the battery cells 29a, 29b and the heat transfer medium flowing into the empty spaces 31. In particular, the surfaces 41 are planar and orthogonal to the direction 28. Meanwhile, the empty spaces 31 are laterally delimited by two opposite side walls (only one is shown in Figure 2), which are preferably part of the casing 21, ie without additional lateral structures.

The battery cells 29a, 29b further comprise respective connectors 42, which are not in contact with the heat exchange medium and are electrically coupled to the negative and positive poles of the battery pack 2 in a generally known and not shown way.

According to an aspect of the present invention, for the empty space 31 of each battery pack element, the inlet area 33 comprises a plurality of nozzles 44, separate and spaced apart, for injecting separate flows of the heat transfer medium into the empty space 31. In other words, the manifold 35 is in communication with the empty space 31 through the nozzles 44. The nozzles 44 have respective axes 46 (Figure 2), which are all parallel to the direction 32. Conveniently, for the empty space 31 of each element of the battery pack, the corresponding nozzles 44 are aligned with each other, so as to form a single row, orthogonal to the axes 46.

Conveniently, for the empty space 31 of each battery pack element, the outlet area 33 comprises a plurality of outlet elements 49, which are separated and spaced from each other so as to form a row parallel to that of the corresponding nozzles 44 In other words, the collector 36 is in communication with the empty space 31 through the output elements 49. The output elements 49 have respective axes 50 (Figure 2) which are parallel to the direction 32. The number of the output elements 49 it can be the same or different with respect to the number of nozzles 44. Preferably, the outlet elements 49 are coaxial with respective nozzles 44.

The nozzles 44 and the outlet elements 49 are coupled to the cell layers in a fluid-tight manner.

With reference to Figure 3, the nozzles 44 have a cross section which decreases progressively, going longitudinally towards the empty space 31, at least in correspondence with a portion 51 (for example, in correspondence with an intermediate portion). In particular, the nozzles 44 have respective outlet openings having a smaller dimension, orthogonal to the direction 28, with respect to that of the empty space 31.

Similarly, the outlet elements 49 have a cross section which increases progressively, going longitudinally towards the empty space 31, at least in correspondence with a portion 52. In particular, the outlet elements 49 are defined by respective funnel-shaped elements.

Thanks to the portions 51 and 52, the heat transfer medium is guided into and out of the empty space 31, in particular to avoid or limit turbulence, and at the same time the flow can increase its speed when it enters the empty space. 31.

In the variant of Figure 4, the directions 32 and 30 are parallel, instead of being orthogonal.

The embodiments in Figures 2 to 4 relate to battery cells (29a and 29b) of the prismatic type.

On the other hand, Figure 5 and Figure 6 show variants in which the battery cells are bag cells, indicated by the reference numbers 29c and 29d. The variant in Figure 5 has the same arrangement as Figures 2 and 3 (i.e., directions 30 and 32 are orthogonal), while the variant in Figure 6 has the same arrangement as Figure 4 (i.e., directions 30 and 32 are parallel) .

In these embodiments, a structure 53 (partially shown) is provided to house and / or support the pouch cells, so as to keep said pouch cells compressed or, more generally, to prevent deformation of the outer surfaces 41 of the bag cells 29c, 29d. The structure 53 is made of a thermally conductive material, preferably a light metal or a light alloy (for example, aluminum). Conveniently, the structure 53 comprises openings or holes 54 (Figure 5), at the surfaces 41, to improve the heat exchange between the heat exchange medium in the empty space 31 and the battery cells 29c, 29d. In addition to or as an alternative to the structure 53, spacers (not shown) can be provided in the empty space 31 to prevent deformation of the outer surfaces 41 of the pouch cells 29c, 29d.

Figures 7, 8 and 9 show other variants, in which the battery cells are of the cylindrical type, indicated by the reference numbers 29e and 29f, and having respective axes 56 orthogonal to the directions 30 and 28.

In the variant of Figure 7, the axes 56 extend orthogonally to direction 39. In this case, the empty space 31 between the two adjacent layers defines a single continuous passage which does not have a constant height (along direction 28), due to of the curved outer surfaces of the cells 29e, 29f.

In the variants of Figures 8 and 9, the axes 56 are parallel to the direction 32. In Figure 8, the axes 56 of the cells 29e are arranged symmetrical to the axes 56 of the cells 29f, with respect to a plane of symmetry extending between the two layers adjacent cells. In Figure 9, the cells 29e and 29f are arranged asymmetrically, for example the axes 56 of the cells 29e in one of the layers are offset with respect to the axes 56 of the cells 29f in the adjacent layer. In the latter case, the nozzles 44 are no longer arranged along a row, but are arranged along two parallel rows.

In these two variants of Figures 8 and 9, the two adjacent cell layers can be in contact with each other, so that the empty space 31 between these two layers defines a plurality of passages, which are parallel to the direction 32 and the axes 56 and which are possibly separated from each other. In Figure 8, each of these passages of the empty space 31 is bounded by the curved outer surfaces of the two successive cells 29e (for one of the two adjacent cell layers) and by the curved convex surfaces of two successive cells 29f (for the other of the two adjacent layers of cells). In Figure 9, each of the passages of the empty space 31 is delimited by the curved outer surfaces of three cells (two cells 29e and one cell 29f, or two cells 29f and one cell 29). The solution in Figure 9 is preferable, compared to that in Figure 8, since the parallel passages have a smaller cross-sectional area. Clearly, in Figures 8 and 9, each of the passages of the empty space 31 is provided with at least one nozzle 44 and at least one outlet element 49.

In use, the heat transfer medium is fed by the high pressure pump 17, so that the heat transfer medium is injected from the nozzles 44 at a high speed into the passage or passages defined by the empty space 31 between two adjacent cell layers. . The pressure should be as high as possible, to provide for faster cooling / heating of the cells, but not too high, otherwise the cooling device 12 will not be able to adequately expel the heat. By way of example, the supply pressure at the inlet area of the battery pack element could be between 1 and 15 bar, and in any case it should preferably be chosen after testing or analysis.

The passage or passages defined by the empty space 31 are designed to be as narrow as possible, along the direction 28, in such a way as to decrease the volume or flow rate necessary to regulate the temperature of the battery pack 2, but they must be large enough to provide adequate cooling / heating to all cells in each layer. This size of the empty space 31 is set in the design phase according to all the characteristics and requirements of the system 14. By way of example, this size can be between 0.5 mm and 15 mm.

The injection of the heat transfer medium into the empty space 31 by means of the nozzles 44 allows for more effective cooling, for example with a very low thermal gradient between the cells.

In particular, the battery cells are immersed in the heat transfer medium, and different flows of this medium are injected for the empty space 31 provided between the two adjacent cell layers. In this way, the distribution of the flow is improved, i.e. the flow rate within the empty space 31 is more uniform along the width of the battery pack 2 (i.e., along a transverse direction orthogonal to the directions 28 and 32). In particular, this improved uniformity is present in the embodiments of Figures 2 to 6 even if the empty space 31 between the two adjacent cell layers defines a single passage, instead of dividing this empty space 31 into multiple parallel passages, with a consequent savings in terms of materials and weight and in terms of assembly time and cost.

Furthermore, the use of different nozzles 44 and different outlet elements 49 for the empty space 31 tends to improve the laminar flow of the heat transfer medium, although a high speed can be obtained thanks to the shape of the nozzles 44 and / or the high supply pressure.

At the same time, the outlet elements 49 collect the heat transfer medium and make it recirculate easily in the cooling device 12 and / or to the heating device 20.

Thanks to these improvements to the cooling / heating process on battery cells, higher power modes can be sustained for longer and with less impact on cell life. In other words, the proposed solutions lead to an increased cell life, a continuous power supply (to provide continuous torque to the vehicles), better SoH and SoC estimates and increased safety.

Finally, it is clear that changes may be made to the battery pack element described, which do not extend beyond the scope of protection as defined by the attached claims.

In particular, the number of nozzles 44 and / or of the outlet elements 49 can be varied to optimize performance.

Claims (1)

CLAIMS 1.- Battery pack element comprising: - first battery cells (29a; 29c; 29e) arranged along a first layer; - second battery cells (29b; 29d; 29f), which are arranged along a second layer parallel to and adjacent to said first layer; - an empty space (31) between said first and said second layer, said empty space (31) defining at least one passage suitable for channeling a flow of a heat carrier medium along a longitudinal direction (32); - an inlet area (33) and an outlet area (34), arranged at opposite ends of said empty space (31) along said longitudinal direction (32), respectively to let the heat transfer medium flow into and outside said empty space (31); characterized in that said inlet area (33) comprises a plurality of nozzles (44) for injecting respective flows of heat transfer medium between said first and said second layer. 2.- Battery pack element according to Claim 1, characterized in that said empty space (31) defines a single passage. 3.- Battery pack element according to Claim 1, characterized in that said empty space (31) defines a plurality of passages parallel to the longitudinal direction (32), each passage being provided with at least one of said nozzles (44). 4.- Battery pack element according to Claim 3, characterized in that said nozzles (44) are arranged in such a way as to form at least one row, orthogonal to said longitudinal direction (32). 5.- Battery pack element according to any one of the preceding claims, characterized in that each of said nozzles (44) comprises at least one portion (51) having a cross-section that progressively decreases, moving towards said empty space (31). 6.- Battery pack element according to any one of the preceding claims, characterized in that said inlet area (33) comprises an inlet manifold (35), which is in communication with said empty space (31) through said nozzles (44 ). 7.- Battery pack element according to any one of the preceding claims, characterized in that said outlet area (34) comprises a plurality of outlet elements (49) for channeling said heat-carrying means out of said empty space (31). 8.- Battery pack element according to Claim 7, characterized in that said output elements (49) are coaxial to respective nozzles (44). 9.- Battery pack element according to claim 7 or 8, characterized by the fact that each of said output elements (49) comprises at least one portion (52) having a cross section which increases progressively, moving towards said empty space (31) . 10.- Battery pack element according to any one of claims 7 to 9, characterized in that said output elements (49) are arranged in such a way as to form at least one row orthogonal to said longitudinal direction (32). 11.- Battery pack element according to any one of claims 7 to 10, characterized in that said outlet area (34) comprises an outlet manifold (36), which is in communication with said empty space (31) through said output elements (49). 12.- Battery pack element according to any one of the preceding claims, characterized in that it comprises a casing (21) which houses said first and said second battery cells; said empty space (31) being laterally delimited by two opposite side walls; at least one of said side walls forming part of said casing (21). 13.- Thermal management system (14) comprising: - a closed circuit (15); - a pump (17) arranged along said closed circuit (15) to feed a heat transfer medium; - at least one heat exchanger (12) arranged along said closed circuit (15) to cool / heat said heat carrier means; And - a battery pack (2) having an inlet port (22) and an outlet port (23) connected to said closed circuit (15), to allow the heat transfer medium to flow in and out; characterized in that said battery pack (2) comprises at least one battery pack element according to any one of the preceding claims; said inlet area (33) being in communication with said inlet (22) and said outlet area (34) being in communication with said outlet (23).