"ELECTRIC BATTERY PACK WITH BATTERY CELLS IN DIRECT CONTACT WITH A FLOW OF A TEMPERATURE-REGULATING LIQUID, WITH UNIFORM DISTRIBUTION OF THE TEMPERATURE-REGULATING LIQUID BETWEEN SEVERAL CELL STACKS"

Description

DESCRIPTION of the industrial invention entitled: “Electric battery pack with battery cells in direct contact with a flow of a thermoregulating liquid, with uniform distribution of the thermoregulating liquid between different cell stacks”, by: CRF Consortium Company, Italian nationality, Strada Torino, 50 - 10043 Orbassano TO. Designated Inventors: Raffaele RICCO; Luca VURRO; Eligio LORUSSO; THIRTY-TWO Maurizio Filippo. Filed on: July 8, 2024 **** DESCRIPTION TEXT Field of invention The present invention relates to an electric battery pack, of the type including: - a battery pack container, - a plurality of battery cell stacks arranged within the battery container battery pack and each including an array of battery cells, - in which the cells of each battery cell stack are arranged in relation to each other parallel, along a first horizontal direction, - in which the battery cell stacks are arranged in one or more parallel rows to a second horizontal direction orthogonal to the first horizontal direction, - where all battery cells of all battery cell stacks are in direct contact with a flow of a thermoregulatory liquid that passes through the battery pack container, for keeping the battery pack within a given temperature range. Known technique Electric battery packs having the above characteristics are known and have been used for some time. Figures 1-4 of the attached drawings refer to a single module of battery of known type. Figure 1 is a schematic perspective view of a battery module known, of the type equipped with a thermoregulation system using a liquid Thermoregulator in direct contact with the cells. The battery module in the figure 1, indicated as a whole by the reference number 1, includes a plurality of prismatic cells 2, arranged aligned along an X direction inside a container 4 and immersed in a flow of a thermoregulating liquid that passes through container 4. In this description, and in the attached drawings, the construction details relating to the thermoregulating liquid supply circuit and to the control of the temperature of the thermoregulating liquid are not illustrated, since they can be made in any known way and also as such details, taken by themselves, do not fall within the scope of the present invention. In in general, the thermoregulating liquid supply system can include a pump to activate the circulation of the liquid and one or more heat exchangers heat to keep the thermoregulating liquid at a desired temperature. The thermoregulating liquid (for example a dielectric oil) can perform both a cooling function, when the temperature of the battery module tends to exceed a predetermined maximum threshold value, as to a cooling function, when the temperature of the battery module tends to fall below a predetermined minimum threshold value. The system of The supply of the thermoregulating liquid is preferably controlled electronically based on signals emitted by one or more sensors located in the drum module. Again, all of the above details are not illustrated here, either. as they can be made in any known way, both as they are not are included, taken separately, within the scope of the invention, also because their Elimination from drawings makes them simpler and easier to use comprehension. Figure 2 is an enlarged-scale perspective view of a battery cell. 2 of prismatic type, comprising an upper surface 2A, two surfaces main opposite 2B, which are arranged inside the container 4 orthogonally to the X direction of cell alignment, two side walls 2c and a lower wall 2d. In the example shown in figure 2, on the wall upper 2A protrude the positive pole 3P and the negative pole 3N of the cell battery 2. However, it is also possible that the two poles 3P, 3N, are arranged on a of the lateral faces 2C of cell 2. According to a technique known to itself, all positive poles are 3P and all negative poles are 3P. 3N of the 2 cells are electrically connected to each other and to the two respective poles P and N protruding, in the example illustrated, from an end wall of the container 4 (see figure 1). Figure 3 is a schematic sectional view in the median vertical plane of the battery module of figure 1. With reference to this figure, the container 4 includes a 5A input opening for the thermoregulating liquid, communicating with an entrance collector chamber 5 arranged below the cell array of battery 2. The container 4 also includes a 6A outlet opening for the liquid thermoregulator, communicating with an output collector chamber 6, arranged at the above the battery cell array 2. Still referring to figure 3, the battery cells 2 are arranged spaced apart from each other in such a way as to define a plurality of spaces 7 which place the chamber in hydraulic communication inlet collector 5 with outlet collector chamber 6. In general, this is obtained by interposing spacer frames between the cells. The set of cells of the frames spacers is kept in an assembled condition by application of a compressive force along the longitudinal direction X (figure 1) by means of any known type, for example by tie rods (not illustrated). The size of the spaces 7 between the cells 2 has been exaggerated for clarity of figure 3. In reality, the distance between two adjacent cells can be for example in the order of a few millimetres (for example about 2 mm). Figure 4 is a partially sectioned perspective view of a module of battery of the known type described above, in which one of the cells 2 has been removed for illustrate a portion of a spacer frame, including a strip lower horizontal 8, which extends along the lower edge of a cell 2, for the entire width of cell 2 (i.e. in the Y direction of figure 1). Figure 5 illustrates a further example of a spacer frame 8, configured to be mounted astride each battery cell, including a plurality of 80 vertical strips intended to be placed on the two sides of a cell, to separate the cell from the adjacent cells. Figure 6 of the attached drawings shows a battery pack of a known type, of the type including a plurality of battery modules 1, each with its own container 4 having a respective 5A input for the thermoregulating liquid. Figure 7 instead shows a solution in which within a single container 4 are arranged more stacks 101 of battery cells 2. A similar arrangement is also illustrated in the diagram in figure 8, which shows a battery pack 100 comprising a container 4 intended to be passed through by the flow of thermoregulatory liquid, inside which are arranged several stacks of cells battery 101 each including an array of battery cells 2. In Figure 8, the spaces between stacks 101 and the spaces between stacks 101 and the container have been exaggerated for clarity. The 2 battery cells of each stack 101 are arranged aligned in the X direction. The various stacks 101 are in turn arranged aligned along two rows in the Y direction. In solutions of the known type such as those illustrated in figure 8, typically at the two opposite ends of container 4 there are two additional spaces 9, both for safety reasons and to contain additional components, such as for example a pump 102 to activate the circulation of the thermoregulating liquid through container 4. The arrangement of figure 7 is particularly advantageous, as allows to maximize the volumetric energy density of the battery pack, minimizing the empty spaces within the container 4. Both in the case of figure 7 and in the case of figure 8, the container has a single inlet for the liquid temperature controller (not shown in these figures). The solution in figure 6, with independent modules 1, has a volumetric energy density lower than in the case of figures 7, 8. Figures 9, 10 show the different layouts of the liquid circuit thermoregulator in two battery packs with 1 independent modules (figure 9) and with 101 stacks of cells contained in a common container to which a single one is associated circuit for the thermoregulating liquid (figure 10). In the case of figure 10, among the several cell stacks are arranged in separating walls. Technical problem In a battery pack of the known type illustrated in figures 7 and 8, with multiple stacks of battery cells arranged within a common container which is crossed by the flow of thermoregulating liquid there is the problem of obtaining a correct thermoregulation of all cells of all battery cell stacks promoting a substantially uniform flow rate of the thermoregulating liquid in the different stacks of battery cells and between the different cells of each stack. The Applicant has already proposed several solutions (see the questions of Italian patents IT102023000022704, IT102023000022698, IT102023000022692, still secret at the priority date of this invention), aimed at obtaining a uniform distribution of the liquid flow thermoregulator between the different spaces between the cells of the same battery module, and in order to make the flow of the thermoregulating liquid uniform in each space between two cells, across the width of the cells. However, in a battery pack having the arrangement of figure 8, there is the further problem, for reasons that will be explained in detail here in the subsequently, to make the flow of the thermoregulating liquid uniform between the different stacks of battery cells. A second technical problem is that of “swelling”, that is, swelling of the battery cells, both due to aging and heating: there are always countermeasures that tend to contain this phenomenon. These countermeasures must not conflict with the solutions aimed at ensuring uniform distribution of the liquid flow thermoregulator. Purpose of the invention The purpose of the present invention is to solve the above problems. technicians. In particular, the invention aims to create a package of electric battery of the type indicated at the beginning of this description, in which the cell temperature is maintained within a certain range at any time operating condition, thanks to the high efficiency of the heat exchange with thermoregulating liquid. Even more specifically, the main purpose of the invention is to optimize the heat exchange between the cells and the thermoregulating liquid thanks to a uniform distribution of the thermoregulating liquid between the different modules of the battery pack and between the different spaces between the cells of each module Summary of the invention In order to achieve one or more of the above-mentioned purposes, the invention has for object an electric battery pack having the characteristics indicated in the attached claim 1. Further advantageous features of the invention are set forth in the dependent claims. Detailed description of the invention Further features and advantages of the invention will result from the description that follows with reference to the attached drawings, provided for information purposes only non-limiting example, where: Figure 1 is a perspective view of a battery module according to the known technique, Figure 2 is a perspective view of a prismatic type battery cell, Figure 3 is a schematic cross-sectional view of the battery module of the figure 1, Figure 4 is a schematic perspective view of a cell array of battery in a battery module according to the prior art, Figure 5 is a perspective view of a further example of a frame spacer, used to space battery cells in the same module of drums from each other, Figure 6 is a perspective view of a known type battery pack with a plurality of modules having independent containers each provided with a respective circuit for the thermoregulating liquid, Figure 7 is a perspective view of a battery pack of a type which is applicable the present invention, with a plurality of battery cell stacks arranged within a common container, Figure 8 is a schematic plan view of a battery pack of the type of figure 7, Figures 9, 10 show the different layouts of the liquid circuit temperature controller in the case of a battery pack with independent modules and a battery pack with a plurality of battery cell stacks immersed in a single circuit for the thermoregulating liquid, Figure 11 illustrates the solid parts of the thermoregulating liquid flows through the battery pack of the invention, Figure 12 is a plan view showing the flow of the liquid temperature controller associated with a battery cell stack forming part of a battery pack according to the invention, Figure 13 is a perspective view illustrating a single battery cell of a stack of battery cells, and the non-conductive material ribs used to support battery cells of the same stack, Figure 14 is an enlarged perspective view of a detail of the figure 13, Figure 15 is a schematic and plan view of the support structure at the base of a stack in the battery pack according to the invention, Figure 16 is a schematic plan view of part of the liquid circuit temperature controller, in a battery pack according to the invention, Figure 17 is a schematic perspective view of a battery cell forming part of an embodiment of the invention, and Figure 18 is a perspective view of a battery pack with cells cylindrical, to which the present invention is also applicable. Figures 1-10, already described above, show known arrangements of modules of battery and battery packs with modules having independent circuits for the liquid temperature controller and battery packs of the type to which the present invention relates, that is, with stacks of cells contained in a common container and immersed in a common circuit for the thermoregulating liquid. The battery pack of the invention may be of the same type as illustrated in the figure 7 and schematized in figure 8, with a container 4 within which are arranged two rows of stacks 101, along directions parallel to the Y direction, with the cells 2 of each stack 101 arranged side by side in the X direction. The Figure 8 is purely schematic, so it does not show the spaces between cells 2, nor shows the construction details of the battery pack 100. Furthermore, in figure 8, as already indicated, the spaces between the stacks 101 and the spaces between the stacks 101 and the container 4 have been exaggerated for clarity. In reality, these spaces are kept as small as possible. possible, to increase the volumetric energy density of the battery pack. Of course, the invention is also applicable to different configurations, with a different number of stack 101 files, with a different number of stack lengths each row and with a different number of cells in each stack. Figure 11 of the attached drawings illustrates, as solid parts, the flows of the thermoregulating liquid through the battery pack according to the invention (is Only one half of the battery pack is shown, with the row of 101 stacks being on one side of the median longitudinal axis 11 of the package in figure 8). The battery pack container is configured in such a way that In each stack 101 the thermoregulating liquid flows from a collecting chamber of 13A input extending below the 2 cells of the stack, through the spaces between the cells and up to an outlet collector chamber 13B which extends to the above the stack cells. In figure 11, for simplicity of illustration, for each stack were illustrated as solid parts the liquid flows thermoregulator through only three of the spaces between the cells of the stack: the two spaces at the ends of the stack and the space halfway along the length of the stack The container 4 is also configured to define a conduit 10 of distribution of the thermoregulating liquid entering container 4, extending below the 101 stacks along the Y direction, starting from a input 12, at a first end 4A of the container 4 towards a second end 4B of container 4, and configured to distribute the liquid thermoregulator to the 13A input collector chambers of the different cell stacks battery 101. Container 4 is also configured to define a collector duct of outlet 14 of the thermoregulating liquid, extending above the stacks 101, along the Y direction, from the aforementioned second end 4B of the container 4 towards said first end 4A of the container 4, up to an exit 15. The duct outlet manifold 14 is configured to collect the liquid flow thermoregulator coming from the output collector chambers 13B of the different stack 101, and to bring it to exit 15. Referring again to figure 11, according to a characteristic important of the present invention, the output collector chambers 13B of the several stacks 101 communicate with said output collector duct 14 via respective openings A1, A2, A3, A4 which have different passage areas, progressively smaller as the distance decreases each stack 101 from the output 15 of the container 4. In this way the different openings A1, A2, A3, A4 prevent the flow rate of the thermoregulating liquid from tending to be progressively larger through stacks that are closer together at the 4A end of the battery pack, where input 12 and output 15 are located. In one example, the A1 opening extends substantially across the entire transverse dimension of the respective outlet collector chamber 13B. The A2 aperture has an area equal to 40-60% of the area of ​​A1. The A3 aperture has an area equal to 20-30% of the area of ​​A1 and the A4 opening has an area equal to 15-20% of the area of A1. Another problem is that the thermoregulating liquid that comes from the distribution pipe 10, pushed by the fuel pump 10, tends to have a stagnation zone, with higher pressure and lower velocity, in the input collector chamber 13A of stack 101 closest to end 4B of container 4, that is, stack 101 which is furthest from input 12. For this reason, the thermoregulating liquid may tend to accumulate at the end 4B of the container 4, thus preventing thermoregulation efficient of the aforementioned cell stack and making the distribution of the thermoregulating liquid between the different cell stacks and also making it uneven the flow distribution in the inlet collector chamber 13A of stack 101 adjacent to end 4B of container 4. To solve the above problem, the invention provides the device which is described below. With reference to figure 16, according to the invention, for the purpose of counteract a tendency of the thermoregulatory liquid to increase excessive pressure at the collector chamber input 13A of stack 101 closest to end 4B of container 4, the part terminal of the thermoregulating liquid distribution duct 10 communicates with the input collector chamber 13A of the aforementioned stack 101 via a labyrinth passage defined by a 10A septum that prevents communication direct between the terminal part of the duct 10 and the inlet collector chamber 13A of the aforementioned stack 101. The septum 10A is shaped in such a way that the flow of the thermoregulating liquid reaches a blind end of the duct 10, where increases in pressure, but then returns to a passage 10B from which it returns to flow to the inlet collector chamber 13A below the cells 2 of the aforementioned stack 101. The labyrinth passage can also be foreseen in correspondence with the other stacks, in the part of duct 10 adjacent to the side of each stack furthest away from entrance 12 (figure 11). The labyrinth passage has the function of decouple the main flow flowing in the conduit 10 from the fluid which, bending 90°, it accesses the different stacks. The partition that defines the passage to labyrinth can be of different length depending on the distance of each stack from input 12: at the last stack (i.e. in the tallest stack) away from the entrance 12) can have an axial length of at least 1 / 3 of the stack size in the Y direction (always referring to the figure 11). In the stack immediately upstream the extension of the septum defining the maze passage can be at least a quarter of the stack size in the Y direction. In the stack still upstream the size in the Y direction of the labyrinth passage can be at least a fifth The trick consists in providing one or more labyrinthine passages of the type described above can also be provided, according to the invention, in a battery pack in which, instead of prismatic cell stacks, stacks are used of cylindrical cells. In this case, the battery cell stacks are defined by a single continuous assembly of cylindrical cells 2 arranged with their axes vertical and in contact between them, so that the spaces between the cylindrical cells communicate the entrance collector chamber located under the cells with the collector chamber of exit located above the cells (figure 18), one or more labyrinth passages being associated with groups of cylindrical cells that are further away from the entrance to the thermoregulating liquid in the container. In the battery pack according to the invention, the cells 2 of each stack of battery cells 101 (see figure 13) are supported on a plurality of ribs 300 straight lines of electrically insulating material, parallel and spaced apart, extending in the longitudinal direction X of each battery cell stack 101. The ribs 300 are immersed in the inlet collector chamber 13A of each battery stack, located below the 2 battery cells. In the preferred embodiment of the invention, in order to reduce the as possible a tendency of the thermoregulating liquid to increase in pressure adjacent to the end 4B of the container 4, a series of 400 upper notches, spaced apart, distributed along the entire length of each rib 300, and positioned each where a respective cell 2 rests on rib 300 (see figure 10). In this way, a uniform distribution of the liquid is promoted thermoregulator coming from the distribution duct 10 for the whole width (along the Y direction) of the inlet collector chamber 13A of the stack 101 adjacent to end 4B of container 4. According to a further preferred feature, with reference to figure 15, the support ribs 300 which are closest to said second end 4B of the container 4 have notches 400 of greater length. Preferably, in the stack 101 which is closest to the second end 4B of the container 4 ribs of support 300 have notches 400 of length L progressively greater than the decrease the distance of rib 300 from the second end 4B of the container 4. Furthermore, always preferably, as illustrated in figure 15, the 400 notches are in positions to encourage a circulatory motion in a plane horizontal of the thermoregulating liquid. With reference to figure 17, according to a further feature advantageous of the preferred form of implementation, the cells 2 of each stack 101 are separated from each other, instead of by frames of the type illustrated in figure 5, by panels 30 of porous material. For example, each panel 30 is made up of one or more layers of a 30A network made of wires of a material chosen based on the need to electrically isolate the cells: in case of low risk of short circuit circuit between the cells (perhaps because they are already sufficiently protected), a steel Stainless steel is the best choice, with mesh wire diameters of around 0.2 mm. On the contrary, in the case of cells with reduced protection, an adequate electrical insulation and therefore preferably a steel can be used stainless steel coated with insulating paint or other protective coating or even a superpolymer such as polyetheretherketone (PEEK), resistant to high temperatures temperatures: in this case the shirt could be made using 3D printing or with multi-layer wrapping. Another advantage of the superpolymers is that they would thermally insulate the cells from each other in the event of a leak uncontrolled thermal (thermal runaway), since the temperature of softening of superpolymers exceeds 200°C. The Applicant's studies and experiences have shown that the use of panels of porous material of the type of panel 30 of figure 17 as elements spacers between the cells allow for a flow of the thermoregulatory liquid in the spaces between the cells much more homogeneous and uniform. In order not to compromise the anti-swelling function (which tends to prevent swelling of the cells during use) fulfilled by the spacer frames rigid ones of the type shown in figure 5, the panel 30 of porous material can include a plurality of rigid inserts 40, for example of plastic material. Preferably, the panels 30 are used in combination with the provision of spacer elements 8 for example of the type illustrated in the figure 4, defining one or more narrow passages for the communication of the chamber 13A input collector located under the 2 cells with the spaces between the cells. As already indicated in the solutions previously proposed by the same Applicant, the aforementioned narrow passages are intended to create resistance to the passage enough thermoregulating liquid to discourage a tendency of the liquid thermoregulator to flow more in the spaces between the cells that are closer at the inlet and / or outlet of the thermoregulating liquid into and from the container 4. Naturally, without prejudice to the principle of the invention, the details of construction and forms of implementation may vary widely from as described and illustrated purely by way of example, without thereby departing within the scope of the present invention, as defined in the appended claims.

Claims

1. An electric battery pack, comprising: - a battery pack container (4), - a plurality of battery cell stacks (101) (2) arranged within the battery pack container (4) and each including an array of battery cells (2), - wherein the cells (2) of each battery cell stack (101) are arranged parallel to each other, and aligned along a first horizontal direction (X), - wherein the battery cell stacks (101) are arranged in one or more rows parallel to a second horizontal direction (Y) orthogonal to the first horizontal direction (X), - wherein all the battery cells (2) of all the battery cell stacks (101) are in direct contact with a flow of a thermoregulating liquid passing through the battery pack container (4), for maintaining the battery pack within a given temperature range,- wherein the battery pack container (4) is configured such that in each stack (101) the thermoregulating liquid flows from an inlet collector chamber (13A) extending below the cell stack, through the spaces between the cells (2) and to an outlet collector chamber (13B) extending above the cells (2) of the stack (101), wherein the container (4) is further configured to define: - an inlet distribution duct (10) for distributing the thermoregulating liquid entering the container (4), extending below the battery cell stacks (101) along the aforementioned second direction (Y), starting from a first end (4A) of the container (4) towards a second end (4B) of the container (4), and configured to distribute the thermoregulating liquid to the inlet collector chambers (13A) of the different battery cell stacks (101),and - an outlet collector duct (14) of the thermoregulating liquid, extending above the battery cell stacks (101), along the said second direction (Y), from the said second end (4B) of the container (4) - 14 - towards the said first end (4A) of the container (4), and configured to collect the flow of the thermoregulating liquid coming from the outlet collector chambers (13B) of the different stacks (101) and to convey it towards an outlet (15) of the container, wherein the outlet collector chambers (13B) of the different stacks (101) communicate with the said outlet collector duct (14) via respective openings (A1, A2, A3, A4) which have different passage areas, which are progressively smaller as the distance of each stack from the said outlet (15) of the container (4) decreases.

2. Battery pack according to claim 1, wherein the terminal part of the inlet distribution duct (10) for the thermoregulating liquid communicates with the inlet collector chamber (13A) of the stack (101) which is closest to said second end (4B) of the container (4) via a labyrinth passage defined by a septum (10A) which prevents direct communication between the terminal part of the inlet distribution duct of the thermoregulating liquid (10) and the inlet collector chamber (13A) of the aforementioned stack (101), said septum (10A) being shaped in such a way that the flow of the thermoregulating liquid reaches a dead end of the inlet distribution duct of the thermoregulating liquid (10), where it increases in pressure, but then returns to a passage (10B) from which it flows again towards the inlet collector chamber (13A) below the cells (2) of the aforementioned stack (101).

3. Battery pack according to claim 2, wherein each battery cell stack (101) comprises parallel and spaced prismatic type battery cells, the battery cells (2) of each adjacent battery cell pair (2) having facing main surfaces (2P), between which spacer elements (8, 80) are interposed, so as to define a space between the cells, one or more labyrinth passages being associated respectively with cell stacks that are furthest from the inlet (12) for the thermoregulating liquid in the container (4).

4. A battery pack according to claim 2, characterized in that the battery cell stacks (101 ) are defined by a group of cylindrical cells arranged with their axes vertical and in contact with each other, whereby the spaces between the cylindrical cells communicate the inlet collector chamber located below the stack (101 ) with the outlet collector chamber located above the stack (101 ), one or more labyrinth passages being associated with groups of cylindrical cells that are furthest from the inlet for the thermoregulating liquid into the container.

5. Battery pack according to claim 1, characterised in that: - the cells (2) of each battery cell stack (101) are supported on a plurality of parallel and spaced ribs (300), extending in the aforementioned first direction (X), - each of said support ribs (300) has a plurality of upper notches (400), distributed along the respective rib (300) and each located in a portion of the rib (300) upon which a battery cell (2) is supported, so as to establish communication between different portions of the input collector chamber (13A) beneath the cells (2) of each stack (101).

6. Battery pack according to claim 5, characterized in that the support ribs (300) which are closer to said second end (4B) of the container (4) have notches (300) of greater length.

7. A battery pack according to claim 5, characterised in that in the battery cell stack (101) which is closest to the second end (4B) of the container (4) the support ribs (300) have notches (400) of progressively greater length as the distance of the rib (300) from the second end (4B) of the container (4) decreases, the notches (400) being preferably arranged in positions such as to encourage a circulatory motion in the horizontal plane of the thermoregulating liquid.

8. Battery pack according to claim 1, characterised in that the cells (2) of each stack (101) are separated from each other by panels (30) of porous material.

9. Battery pack according to claim 8, characterised in that the panels (30) of porous material each comprise one or more layers of a mesh (30A).

10. Battery pack according to claim 8, characterised in that the panels (30) of porous material each include a plurality of rigid inserts (40) having the function of tending to prevent swelling of the battery cells (2) during their use.