Battery unit with battery cells in direct contact with a temperature-regulating liquid

Abstract

An electric battery unit (1) comprises an array of battery cells (2) disposed within a container (4) and configured to be in direct contact with a flow of a temperature-regulating liquid passing through the container (4), for maintaining the battery unit (1) within a determined temperature range. The container (4) comprises an inlet collector chamber (5) and an outlet collector chamber (6) for the temperature-regulating liquid, arranged on opposite sides of the array of battery cells and communicating with each other via spaces (7) between the battery cells (2). Each space (7) between the cells (2) communicates with the inlet collector chamber (5) via one or more restricted passages (9) for the temperature-regulating liquid, configured to generate sufficient resistance to the passage of the temperature-regulating liquid to prevent the temperature-regulating liquid from tending to flow to a greater extent into the spaces that are closer to the inlet opening (5A) and / or the outlet opening (6A) of the container (4). A plate (10) separates the inlet collector chamber (5) from the battery cells (2). Each restricted passage (9) communicates with a respective space (7) between the battery cells (2) through an opening (9; 90; 91) that is formed in said plate (10) and that is elongated in a direction (X) orthogonal to the main surfaces of the cells (2) by a length sufficient to ensure communication of the opening with the respective space (7) between the cells, even in the case of variations in the position of the cells (2) with respect to the plate (10) due to manufacturing and / or assembling tolerances.

Description

[0001] Battery unit with battery cells in direct contact with a temperatureregulating liquid

[0002] TEXT OF THE DESCRIPTION

[0003] Field of the invention

[0004] The present invention relates to an electric battery unit of the type comprising an array of battery cells disposed within a container and configured to be in direct contact with a flow of a temperature-regulating liquid passing through the container, for maintaining the battery unit within a determined temperature range,

[0005] - wherein said container includes an inlet opening for the temperature-regulating liquid, communicating with an inlet collector chamber arranged on one side of the array of battery cells and an outlet opening for the temperature-regulating liquid communicating with an outlet collector chamber, arranged on another side of the array of battery cells,

[0006] - wherein the battery cells each have opposite main surfaces orthogonal to the direction of alignment of the cells, the cells being arranged spaced from each other, so that spaces are defined between the cells that hydraulically connect the inlet collector chamber to the outlet collector chamber,

[0007] - wherein each space between the cells communicates with the inlet collector chamber via one or more restricted passages for the temperatureregulating liquid configured to generate sufficient resistance to the passage of the temperature-regulating liquid to prevent the temperature-regulating liquid from tending to flow to a greater extent into the spaces that are closer to the inlet opening and / or the outlet opening of the container.

[0008] Prior art

[0009] Electric battery units having the features indicated above have been known and used for some time. Figures 1 -6 of the appended drawings refer to a battery unit of this known type. The description of such figures is also useful for the understanding of the present invention, since the general features of the battery unit of Figure 1 are the same also in the case of the invention.

[0010] Figure 1 is a schematic perspective view of a known battery unit, of the type provided with a temperature-regulating system using a temperature-regulating liquid in direct contact with the cells. The battery unit of figure 1 , indicated as a whole with the reference number 1 , includes a plurality of prismatic cells 2, arranged aligned along a X direction inside a container 4 and immersed in a flow of a temperature-regulating liquid that passes through the container 4.

[0011] In the present disclosure, and in the annexed drawings, the construction details relating to the temperature-regulating liquid supply circuit and to the temperature control of the temperature-regulating liquid are not illustrated, since they can be made in any known way and also since such details, taken separately, do not fall within the scope of the present invention. In general, the temperature-regulating liquid supply system can include a pump to activate the circulation of the liquid and one or more heat exchangers to maintain the temperature-regulating liquid at a desired temperature. The temperature-regulating liquid (e.g. dielectric oil) can perform both a cooling function, when the temperature of the battery unit tends to exceed a predetermined maximum threshold value, and a refrigeration function, when the temperature of the battery unit tends to fall below a predetermined minimum threshold value. The supply system of the temperature-regulating liquid is preferably electronically controlled on the basis of the signals emitted by one or more sensors arranged in the battery unit. Again, all the above details are not illustrated here, both because they can be made in any known way, both because they do not fall, taken individually, within the scope of the invention, and also because their elimination from the drawings makes the latter simpler and easier to understand.

[0012] Figure 2 is an enlarged perspective view of a prismatic battery cell 2, comprising a top surface 2A, two opposite main surfaces 2B, which inside the container 4 are arranged orthogonally to the X direction of cell alignment, two side walls 2C and a bottom wall 2D. In the example illustrated in figure 2, the positive pole 3P and the negative pole 3N of the battery cell 2 protrude from the top wall 2A.

[0013] According the prior art, all the positive poles 3P and all the negative poles 3N of the cells 2 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 ).

[0014] Figure 3 is a schematic sectional view in the median vertical plane of the battery unit of Figure 1 . With reference to this figure, the container 4 includes an inlet opening 5A for a temperature-regulating liquid, communicating with an inlet collector chamber 5 arranged below the array of battery cells 2. The container 4 also includes an outlet opening 6A for the temperature-regulating liquid, communicating with an outlet collector chamber 6 arranged above the array of battery cells 2. Again with reference to Figure 3, the battery cells 2 are arranged spaced from each other in such a way as to define a plurality of spaces 7 which place the inlet collector chamber 5 in hydraulic communication with the outlet collector chamber 6. In general, this is achieved by interposing spacer frames between the cells. The set of cells of the spacer frames is held in an assembled condition by applying a compressive force along the longitudinal X direction (figure 1 ) by means of any known type, for example by tension rods (not illustrated). The size of the spaces 7 between the cells 2 has been exaggerated for clarity in figure 3. In reality, the distance between two adjacent cells may be, for example, in the order of a few millimeters (e.g. about 3 mm).

[0015] Figure 4 is a partially sectioned perspective view of a battery unit of the known type described above, in which one of the cells 2 has been removed to show a portion of a spacer frame, comprising a lower horizontal strip 8, which extends along the lower edge of a cell 2, across the width of the cell 2 (i.e. in the Y direction of figure 1 ).

[0016] Figures 5, 6 are a perspective view of a pair of battery cells 2 separated by the lower horizontal strip 8 and a sectional view of a transverse plane of the array of battery cells, illustrating a solution according to the prior art. In this prior art solution, the lower horizontal strip 8, interposed between each pair of adjacent battery cells 2, has a plurality of notches formed through the entire thickness of the strip 8, which extend from the upper edge 8A of the strip 8 to a bottom end 9A, which is below the lower wall 2D of the cell 2 and therefore communicates with the inlet collector chamber 5.

[0017] In the aforementioned prior art solution, the notches 9 define an equal number of restricted passages for the temperature-regulating liquid, distributed at a distance from each other along the length of the strip 8 (i.e. in the Y direction of the width of the cell 2). Further passages are defined between the ends of the strip 8 and the walls of the container 4 facing them.

[0018] In the aforementioned known solution, the restricted passages 9 provide a sufficient resistance to the flow of the temperature-regulating liquid to prevent the temperature-regulating liquid from following the shortest path between the inlet 5A and the outlet 6A (see figure 3), preferring the spaces between the cells 2, which are closer to the inlet 5A and / or to the outlet 6A. Due to the flow resistance provided by the restricted passages 9, defined by each strip 8, the flow rate of the temperature-regulating liquid coming from the inlet 5A is uniformly distributed in all the spaces 7 between the cells 2, along the entire length of the battery unit 1 in the X direction, which favors a uniformity of the temperature-regulating effect across the entire battery unit. Furthermore, the provision of several restricted passages 9, distributed along the length of each strip 8, ensures that the temperatureregulating liquid is distributed, within each space 7 between adjacent cells, in a substantially uniform manner along the width of the cells.

[0019] A drawback of known solutions of the type illustrated in figures 5, 6, lies in the risk of liquid leakage between the contact surfaces of the strip 8 and the cells between which the strip 8 is interposed. To avoid such leakage, it is necessary to ensure sufficient contact pressure between the strip and the cells. However, since the contact involves almost all of each face of the strip, the contact surface is relatively large, so that sufficient contact pressure can only be obtained by applying to the cell pack a relatively high compressive force in the longitudinal X direction (figure 1 ) of the unit.

[0020] To overcome this problem, a solution of the type illustrated in figure 7 has also been proposed. In this solution too, each space 7 between the cells 2 communicates with the inlet collector chamber 5 via one or more restricted passages 9. However, in this case, the restricted passages are defined by holes formed in a plate 10 that separates the cells 2 from the inlet collector chamber 5. At each space 7 between the cells 2 and at the spaces between the ends of the cell pack and the end walls of the container, the plate 10 has a plurality of restricted holes 9 (for example circular holes), distributed along the transverse Y direction of the unit.

[0021] The drawback of the known solution of figure 7 lies in the fact that the relative position between the restricted holes 9 of the plate 10 and the spaces 7 between the cells 2 depends on the manufacturing and assembling tolerances of the cells. The sum of the tolerances in a large assembly of cells can lead to several tens of millimeters of relative displacement, so that there is a risk that the restricted holes 9 will be partially or completely blocked by the lower walls of the cells 2, as illustrated by way of example in the two cases of figures 8 and 9 of the attached drawings. In this situation, it is not possible to maintain control over the flow of the temperature-regulating liquid through the various spaces 7 and in particular the possibility of ensuring uniform distribution of the flow in all the spaces between the cells is lost.

[0022] Therefore, there is a need for improvements in this field.

[0023] Object of the invention

[0024] It is therefore an object of the present invention to provide a battery unit of the type indicated at the beginning of this disclosure, which allows the aforementioned technical problem to be solved effectively.

[0025] In particular, an object of the invention is to provide a battery unit of the type specified above in which the uniformity of the flow of the temperature-regulating liquid through the different spaces between the battery cells is ensured without the need to require precise manufacturing and assembling tolerances.

[0026] A further object of the invention is to achieve the above objectives with a simple and low-cost structure.

[0027] Summary of the invention

[0028] In order to achieve one or more of the aforementioned purposes, the invention has as its object an electric battery unit having the features that have been indicated at the beginning of this disclosure and further characterized in that it comprises a plate that separates the input collector chamber from the battery cells and in that each of said restricted passages communicates with a respective space between two battery cells through an opening that is formed in said plate and that is elongated in a direction orthogonal to the main surfaces of the cells, i.e. in the direction of alignment of the cells, by a length sufficient to ensure communication of the opening with the respective space between the cells even in the case of variations in the position of the cells with respect to the plate due to manufacturing and / or assembling tolerances.

[0029] Thanks to the aforementioned feature, variations in the dimensions of the cells and in their positioning, due to manufacturing and assembling tolerances, do not produce a variation in the passage section of the temperature-regulating liquid through each restricted passage and do not cause any drawback with regards to the control of the flow rate of the temperature-regulating liquid through the spaces between the cells.

[0030] In a first embodiment, said opening is elongated in the form of a slit and it constitutes in itself said restricted passage, the width of the slit in the direction orthogonal to the longitudinal direction of the slit being sufficiently small to create the necessary resistance to the flow of the temperatureregulating liquid.

[0031] In a second embodiment, each elongated opening comprises a slot formed in the surface of said plate facing the battery cells and having a bottom wall into which a hole constituting said restricted passage opens.

[0032] In a third embodiment, the plate separating the inlet collector chamber from the battery cells comprises two plate elements superimposed on each other. Each elongated opening is formed in the plate element that faces the cells and communicates with a hole constituting said restricted passage that is formed in the other plate element. In the case of this embodiment, the plate element that faces the cells may be made of elastomeric material, to also fulfil a sealing function between the lower plate element and the cells.

[0033] In all the embodiments described above, spacer frames may be provided between the cells, in the form of peripheral frames, each having an upper horizontal side, a lower horizontal side and two vertical sides. Each frame may have portions of enlarged thickness, which are the only portions of the frame in contact with the cells, only at portions of the frame, for example at four comers of the frame.

[0034] Detailed description of the invention

[0035] Further features and advantages of the invention will be apparent from the following description with reference to the attached drawings, provided purely by way of non-limiting example, in which: figure 1 is a perspective view of an electric battery unit of the type to which the present invention is applicable, figure 2 is a perspective view of a battery cell forming part of the unit of figure 1 , figure 3 is a schematic sectional view in a median vertical plane of the battery unit of figure 1 , figure 4 is a partially sectioned perspective view, with one cell removed, showing a spacer strip used in a prior art battery unit, figure 5 is a perspective view of a pair of cells of the prior art battery unit illustrated in figure 4, figure 6 is a sectional view of the prior art battery unit illustrated in figure 4, in a plane transverse to the longitudinal direction of the battery unit, figure 7 is a partial sectional view of a battery unit according to a further prior art, figures 8, 9 illustrate the same solution as figure 7 in two different assembly conditions, figure 10 is a plan view of a plate used in a first embodiment of the battery unit according to the invention, figure 11 is a partial perspective view of the battery unit according to the first embodiment of the invention, figure 12 is a further perspective view of the battery unit according to the first embodiment of the invention, with most of the cells removed, for clarity of illustration, figure 13 is an enlarged perspective view of a detail of the battery unit of figure 12, figure 14 is a further partial perspective view of the battery unit of figures 12, 13, figure 15 is a further partial sectional view of the battery unit according to the first embodiment of the invention, figures 16, 17 illustrate the same sectional view of figure 15 with reference to two different assembly conditions, figure 18 is a further schematic sectional view of the battery unit according to the first embodiment of the invention, figure 19 is a partial perspective view of the plate interposed between the battery cells and the input collector chamber in a second embodiment of the battery unit according to the invention, figure 20 is an enlarged perspective view of a detail of figure 19, figure 21 is a perspective view of the plate separating the battery cells from the input collector chamber of the battery unit in a third embodiment of the invention, figure 22 is an enlarged perspective view of a detail of figure 21 , figure 23 is an enlarged and partially sectioned view of a detail of figure 22, and figures 24, 25 are sectional views of the battery unit according to the third embodiment of the invention, in two different assembly conditions.

[0036] The battery unit according to the invention has a general configuration of the same type as that described above with reference to Figures 1 -3. Furthermore, the battery unit according to the invention has in common with the solution illustrated in figure 7 the fact that also in it each space 7 between the cells 2, and preferably also the spaces 7 between the ends of the cell pack and the walls of the container, communicates with the inlet collector chamber 5 through one or more restricted passages 9, which have the function of opposing the flow with sufficient resistance to ensure that the temperature-regulating liquid does not tend to flow to a greater extent into the spaces 7, that are closer to the inlet opening 5A and / or the outlet opening 6A.

[0037] Figure 10 is a plan view of the plate 10 that is provided in the battery unit according to the invention between the inlet collector chamber 5 and the battery cells 2. At each space 7, the plate 10 also has a plurality of restricted passages 9, distributed in the transverse Y direction of the unit. However, unlike the known solution illustrated in figure 7, the embodiment of figures 10-18 provides restricted passages 9 in the form of elongated slots in the direction orthogonal to the main faces of the cells 2, i.e. in the X direction of the alignment of the cells 2.

[0038] Each slot 9 has a width p (see figure 13) sufficiently small to produce a desired resistance to the flow of the temperature-regulating liquid. At the same time, the longitudinal length Z (see figure 13) of each slot 9 is sufficiently high to ensure that the slot remains in communication with the space 7 between the cells 2 adjacent to it, whatever the final positioning of the cells 2 with respect to the plate 10, as a result of the manufacturing and assembling tolerances. Figure 15 of the accompanying drawings shows the case of a nominal positioning of the cells 2 with respect to the plate 10, whereby each space 7 between the cells is centered with respect to a respective slot 9. In Figure 15, “L” indicates the dimension of each cell 2 in the X direction of the alignment of the cells, “S” indicates the dimension of the space 7 between the cells in the X direction, “Z” indicates the longitudinal dimension of each slot 9, and “d” indicates the length of the portion of the slot 9 that is covered by a cell 2.

[0039] Figures 16, 17 show two staggered assemblies in opposite directions. In the case of figure 16, the cells have a dimension “L2” in the X direction that is smaller than the dimension L of figure 15, while in the case of figure 17, the dimension “L1” of the cells is larger than the dimension “L” of figure 15. Consequently, in the two cases of figures 16, 17, each space 7 between the cells is displaced to one side or the other with respect to the center of each slot 9. Consequently, the part of each slot that is covered by a cell 2 becomes “d2” in the case of figure 16 and “d1” in the case of figure 17. In both cases, as can be seen, communication between each slot 9 and the respective space 7 is still ensured. With reference again to figures 12 and 14, each spacer frame 11 is in the form of a peripheral frame, with an upper horizontal side, a lower horizontal side and two vertical sides. As can be seen in the detail of figure 14, the lower horizontal side of each frame 11 has a lower edge 110, spaced from the upper surface of the plate 10, so as not to even partially cover each slot 9.

[0040] Still with reference to the spacer frames 11 , in the example illustrated, they have thickened portions 12 which constitute the only portions of each frame that are in contact with the battery cells 2. In the example, these thickened portions are provided at the four corners of each peripheral frame 11 . In this way, the contact surface between each frame and the cells is relatively small, which allows high contact pressures to be obtained even with a relatively small compressive force applied to the entire battery unit in the longitudinal X direction.

[0041] As is evident from the preceding description, each slot 9 has a length much greater than the dimension “S” of the respective space between the cells, which allows the desired passage section to always be maintained, even in the case in which the manufacturing and assembling tolerances involve a relative displacement of the cells 2 with respect to the plate 10. The passage area of the temperature-regulating liquid to reach each space 7 is always the same, so that the flow rate of the temperature-regulating liquid is always uniform and controlled. The frames 11 between the cells 2 have the function of spacing the cells 2 equally, so that the effective passage sections of the temperature-regulating liquid are well determined, which determines a pressure that is always equal in the spaces 7 between the cells. There are therefore no differences in pressure between the spaces 7 between the cells, which prevents a leakage of the temperature-regulating liquid between the plate 10 and the cells. The absence of a tendency of the liquid to leak allows to avoid the application of an excessive compressive force to the array of cells.

[0042] This situation is schematized in figure 18, where “P” indicates the pressure in the inlet collector chamber 5, “p” indicates the pressure of the temperature-regulating liquid in each space 7 between the cells 2. “Q” indicates the total flow rate of the temperature-regulating liquid entering and exiting the array, and “q1”, “q2”, “qn” indicate the flow rates of the temperature-regulating liquid in the different spaces 7, which are generally equal to each other.

[0043] Figure 19 illustrates the plate 10 interposed between the cells 2 and the inlet collector chamber 5 in a second embodiment of the invention. In this case, the restricted passages 9 are constituted by restricted holes 9, for example circular holes, each of which opens onto a bottom wall of a slot 90 formed in the face of the plate 10 facing the cells 2. As illustrated in detail in figure 20, each slot 90 has a flat bottom surface, into which the restricted hole 9 opens, extends by a length Z in the X direction and by a width L in the Y direction. The slot 90 has a depth H.

[0044] In the solution of figures 19, 20, each restricted passage is constituted by the hole 9, but this restricted passage communicates with the respective space 7 between the cells 2 through an elongated opening, leading the upper surface of the plate 10, which therefore ensures a correct communication between the restricted hole 9 and the respective space 7, even in the case of misalignments of the cells 2 with respect to the plate 10, due to manufacturing and / or assembling tolerances.

[0045] Figures 21 -25 show a third embodiment, wherein each plate 10 comprises two superimposed plate elements, an upper plate element 100 and a lower plate element 101. Each restricted passage consists of a restricted hole 9 formed in the lower plate element 101 . Each restricted hole 9 communicates with the respective space 7 between two cells of the battery unit through an elongated opening 91 formed in the upper plate element 100, through its entire thickness. The result, illustrated in Figure 22, is similar to that of figure 20 relating to the second embodiment. Figures 24, 25 show the solution of figures 21 -23 in an assembly condition in which each space 7 is centered with respect to each restricted hole 9 (figure 24) and in a condition in which, due to a different assembly, each restricted hole 9 would be covered by a cell 2 but is still kept correctly in communication with the respective space 7 by the opening 91 associated with it.

[0046] Of course, notwithstanding the principle of the invention, the construction details and the embodiments may vary widely with respect to what is described and illustrated purely by way of example, without thereby departing from the scope of the present invention, as defined in the attached drawings.

Claims

CLAIMS1. An electric battery unit (1 ), comprising an array of battery cells (2) disposed within a container (4) of the battery unit (1 ), and configured to be in direct contact with a flow of a temperature-regulating liquid passing through the container, for maintaining the battery unit (1 ) within a determined temperature range,- wherein said container (4) includes an inlet opening (5A) for the temperature-regulating liquid, communicating with an inlet collector chamber (5) arranged on one side of the array of battery cells (2) and an outlet opening (6A) for the temperature-regulating liquid, communicating with an outlet collector chamber (6) arranged on another side of the array of battery cells (2),- wherein the battery cells (2) each have opposing main surfaces (2B) orthogonal to the direction (X) of alignment of the cells (2), the cells being arranged spaced from each other, so that spaces (7) are defined between the cells (2) that hydraulically connect the inlet collector chamber (5) to the outlet collector chamber (6),- wherein each space (7) between the cells (2) communicates with the inlet collector chamber (5A) via one or more restricted passages (9) for the temperature-regulating liquid, configured to generate sufficient resistance to the passage of the temperature-regulating liquid to prevent the temperature-regulating liquid from tending to flow to a greater extent into the spaces (7) that are closer to the inlet opening (5A) and / or the outlet opening (6A) of the container (4), said battery unit (1 ) being characterized in that it comprises a plate (10) that separates the inlet collector chamber (5) from the battery cells (2) and in that each restricted passage (9) communicates with a respective space (7) between two battery cells (2) through an opening (9; 90; 91 ) that is formed in said plate (10) and that is elongated in a direction (X) orthogonal to the main surfaces (2B) of the battery cells (2), by a length (Z) sufficient to ensure communication of the opening (9; 90; 91 ) with the respective space (7) between the cells (2) even in the case of variations in the position of the cells (2) with respect to the plate (10) due to manufacturing and / or assembling tolerances.

2. The battery unit according to claim 1 , characterized in that said elongated opening (9) is in the form of a slit and it constitutes in itself said restricted passage (9), the width of the slit (9) in the direction (Y) orthogonal to the longitudinal direction (X) of the slit (9) being sufficiently narrow to create said resistance to the flow of the temperature-regulating liquid.

3. The battery unit according to claim 1 , characterized in that each elongated opening comprises a slot (90) formed in the surface of said plate (10) facing the battery cells (2) and having a bottom wall into which a hole (9) constituting said restricted passage opens.

4. The battery unit according to claim 1 , characterized in that said plate (10), which separates the inlet collector chamber (5) from the battery cells (2), comprises two plate elements (100, 101 ) superimposed on each other, and in that each elongated opening (91 ) is formed in the plate element (100) facing the battery cells (2) and communicates with a hole (9) constituting said restricted passage which is formed in the other plate element (101 ).

5. The battery unit according to claim 4, characterized in that said plate element (100), facing the battery cells (2), is made of elastomeric material to also fulfil a sealing function.

6. The battery unit according to any of the preceding claims, characterized in that there are interposed between the battery cells (2) spacer frames (11 ) in the form of peripheral frames, each having an upper horizontal side, a lower horizontal side and two vertical sides, and in that each frame has contact surfaces with the cells (2) limited only to a few portions (12) of enlarged thickness of said frame, preferably located at the four comers of each frame.

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