Cooling arrangement for a motor vehicle for compensating a charge-induced swelling of storage cells and method for operating a cooling arrangement

Abstract

The invention relates to a cooling arrangement (10) for a motor vehicle, wherein the cooling arrangement (10) comprises an energy store (12) with at least one storage cell (14), a cooling circuit (18) through which a coolant (16) can flow, having a cooling chamber (20) through which the coolant (16) can flow, in which at least part of the storage cell (14) is arranged, and a pressure control device (24) for setting a specific coolant pressure (p) in the cooling chamber (20) when the coolant (16) flows through it. The cooling arrangement (10) comprises a structural component (48) formed at least in part with a cavity (46), and a volume expansion tank arrangement (40) provided at least in part by the structural component (48) and its cavity (46), which is or can be fluidically coupled to the cooling chamber (20).

Description

[0001] The invention relates to a cooling arrangement for a motor vehicle, comprising an energy storage device with at least one storage cell, a cooling circuit through which a coolant flows, and a cooling chamber through which the coolant flows, in which at least part of the storage cell is arranged, and a pressure regulating device for setting a specific coolant pressure in the cooling chamber when the coolant flows through it. The invention further relates to a method for operating a cooling arrangement.

[0002] Batteries, for example, automotive batteries, especially high-voltage batteries for electric vehicles, or for electrical appliances, currently predominantly use lithium-ion cells in various packaging forms such as cylindrical cells, prismatic cells (also known as cans), or pouch cells. For applications with high demands on lifespan, charging speed, discharging speed, and so on, it is also advantageous if the cells can be actively temperature-controlled, especially cooled. In battery cells with so-called immersion cooling, temperature control is achieved via a cooling medium, also called a coolant, which flows directly around the cells. This means that this coolant can come into direct contact with at least part of the cell casing or even with the entire cell.For example, such cells can be positioned in a cooling chamber through which a liquid flows. The cells can be completely immersed in the cooling medium. This allows for significantly more efficient cooling than, for example, using cooling plates attached to the cells with integrated channels through which a coolant flows. Furthermore, within the framework of immersion cooling, it is also possible to use the cooling medium to exert a homogeneous pressure on the cells, as described, for example, in DE 10 2018 215 477 A1. For this purpose, a pressure pump, a pressure control valve, and a refill reservoir can be used, for example, to supply or discharge the coolant into or out of the housing containing the battery cells, depending on a predetermined coolant pressure, in order to maintain a predefined coolant pressure within the housing.

[0003] Electrochemical processes cause the volume of the active material in a battery cell to increase within the foil winding or stack. This increase in volume is called swelling. To compensate for swelling, or to apply a defined pressure to the cells to enable controlled swelling, so-called cell separators are often used, positioned between the battery cells. Uncontrolled swelling, as well as completely suppressed swelling, leads to a reduced lifespan.

[0004] DE 10 2020 118 542 B3 describes a battery module with battery cells and cell separators arranged between them. Such a cell separator can be designed to deform depending on the swelling state of the battery cells.

[0005] Furthermore, DE 10 2022 109 173 A1 describes a device for pressure relief for a battery cell stack consisting of several battery cells stacked along a stacking direction. The device comprises a base body and a flexible fluid reservoir filled with a fluid. The device also includes a compensation chamber.

[0006] However, such cell separation elements are not designed to allow flow through them and, in combination with immersion cooling, would reduce cooling efficiency, as this reduces the outer surface area of ​​the cells that can be exposed to the coolant.

[0007] In immersion cooling, the expansion of the cells displaces a certain volume of coolant. This displacement can be suppressed, but this leads to a significant pressure increase, which can negatively impact the lifespan of the cells. If, on the other hand, the expansion of the cells is allowed, the displaced volume must be accommodated, which in turn requires a considerable amount of additional installation space.

[0008] The object of the present invention is to provide a cooling arrangement and a method that enable the most efficient possible cooling of battery cells by means of immersion cooling in a space-saving manner.

[0009] This problem is solved by a cooling arrangement and a method with the features according to the respective independent patent claims. Advantageous embodiments of the invention are the subject of the dependent patent claims, the description, and the figures.

[0010] A cooling arrangement according to the invention for a motor vehicle comprises an energy storage device with at least one storage cell, a cooling circuit through which a coolant flows, and a cooling chamber through which the coolant flows, in which at least part of the storage cell is arranged, and a pressure control device for setting a specific coolant pressure in the cooling chamber when the coolant flows through it. The cooling arrangement includes a structural component that is at least partially formed with a cavity, and a volume expansion tank arrangement that is at least partially provided by the structural component and its cavity, which is fluidically coupled or can be coupled to the cooling chamber.

[0011] The invention is based on the understanding that motor vehicles contain numerous structural components, such as body panels, frame components, supports, and the like, which often have a cavity that frequently remains unused. Such a structural component with a cavity can, for example, be provided in the form of a hollow profile component. These cavities in such structural components can advantageously be used to accommodate the volume expansion tank arrangement, or at least a part thereof. The cavity of such a structural component can be connected to the cooling compartment, for example, via a valve, to receive coolant displaced from the cooling compartment to provide volume compensation during the swelling of the at least one battery cell. This advantageously eliminates the need for a separate volume expansion tank.No additional volume is required to accommodate the displaced coolant, and consequently, additional components, weight, and above all, installation space can be saved.

[0012] The cooling arrangement can generally be an immersion cooling system as described above. In other words, the cooling arrangement can be designed as described in the section on immersion cooling. Specifically, the cooling arrangement can be configured such that when the cooling chamber is traversed by the coolant, the coolant directly contacts or flows onto at least a portion of the cell housing of the at least one storage cell. The storage cell does not necessarily have to be completely within the cooling chamber through which the coolant flows. For example, it can be provided that a portion of this storage cell is located outside this cooling chamber through which the coolant flows, such as one or more cell poles of the storage cell, which then cannot come into contact with the coolant flowing through the cooling chamber.However, it can also be provided that the entire storage cell is arranged within this flow-through cooling space, so that, for example, the entire outside or almost the entire outside of such a storage cell can be brought into contact with the coolant when it flows through the cooling space.

[0013] The coolant is preferably a liquid. This significantly increases cooling efficiency. However, a gaseous coolant is also conceivable. Furthermore, the coolant can be an electrically insulating coolant, such as cooling oil, or an electrically conductive coolant, such as water. The latter is particularly suitable if, for example, live parts of the battery cell are located outside the cooling chamber.

[0014] Furthermore, the energy storage system can comprise not just one such storage cell, but several. These multiple storage cells can be located in the same cooling chamber, or at least partially located within this shared cooling chamber. Optionally, the energy storage system can also comprise several battery modules, each containing multiple storage cells, in which case, for example, a separate cooling chamber can be provided for each battery module. However, the storage cells of several battery modules can also be located, at least partially, within a shared cooling chamber, meaning that at least a portion of each of these storage cells is located in the same cooling chamber.

[0015] The storage cells can be designed, in particular, as battery cells. The energy storage device can be a battery, especially a high-voltage battery for motor vehicles. However, the energy storage device can also be a medium-voltage or low-voltage battery. Furthermore, the energy storage device can also be a stationary energy storage system. The storage cells can be, for example, lithium-ion cells or any other cell chemistry. In addition, the storage cells can be designed as prismatic battery cells, pouch cells, and / or cylindrical cells.

[0016] Furthermore, if the energy storage system comprises several storage cells arranged in the same cooling chamber, a coolant-flowable space can be formed between the storage cells. This flowable space can be designed as a structure-free cavity or empty space. Optionally, cell separators, also allowing coolant flow, can be arranged between the storage cells. Such cell separators can exert additional pressure on the storage cells, in addition to the coolant pressure. This allows the coolant pressure in the cooling chamber to be reduced. As a result, the cooling chamber and the entire coolant-flowable cooling circuit can be designed more simply, since it no longer needs to be designed for such high pressures. However, it is also conceivable to completely dispense with cell separators or other elements located between the battery cells.This allows for a particularly efficient cooling effect.

[0017] The cooling arrangement, in particular the pressure regulating device, can be configured to set the coolant pressure in the cooling chamber to a pressure between, for example, 1 bar and 20 bar, or between, for example, 1.5 bar and 10 bar. For instance, it can be provided that a lower coolant pressure, for example, of 1.5 bar, is set in the cooling chamber at the beginning of the storage cell's service life, and a higher coolant pressure, for example, in the range of approximately 10 bar, is set at the end of the service life, with the pressure gradually increasing from the lower to the higher coolant pressure over the course of the service life.When determining a suitable pressure for the storage cells, various other parameters can also be taken into account, such as the temperature of the coolant or the storage cells, the cell chemistry of the storage cells, the operating state of the storage cells (e.g., whether they are currently charging or discharging, or not undergoing any charge change), the current state of charge of the storage cells, and so on. Such optional, freely programmable pressure application by the coolant medium makes it possible to apply the optimal pressure to the cells for the respective requirement.

[0018] Furthermore, the pressure control device can be designed not only to set a specific coolant pressure in the cooling chamber, but also to regulate it to a given value, whereby this value can be selected based on the parameters mentioned above and can also be changed over time. For pressure control, the cooling system in the cooling circuit can also include at least one pressure sensor.

[0019] The cavity of the structural component does not necessarily have to be permanently coupled to the cooling chamber, but can also be fluidically coupled to it as needed, for example via a valve device or similar.

[0020] According to a further advantageous embodiment of the invention, the structural component represents a body structure and / or a support or frame, particularly as part of a housing for the energy storage device. The latter is especially advantageous because it allows structural components near the storage cell to be used as expansion tanks in the volume expansion tank arrangement. The energy storage device can thus comprise a battery housing, which, for example, has a frame surrounding a receiving area in which the storage cells of the energy storage device are arranged. This frame can be designed in one piece or in multiple parts, for example, comprising two longitudinal struts and two transverse struts, and optionally also intermediate struts for stiffening. Such struts or frame parts can, for example, be designed as hollow profiles, at least in sections.Such cavities in hollow profiles, as part of the frame, can advantageously be used to function as reservoirs for the volumetric expansion tank system. The fluidic connection to the cooling circuit is then extremely simple due to the proximity to the storage cells. Furthermore, the reservoir of the volumetric expansion tank system is in a particularly protected position when it is located in such a cavity within a structural component. This makes a leakage resulting from a crash or similar event all the more unlikely. Thus, safety can also be increased.

[0021] According to a further advantageous embodiment of the invention, the cooling arrangement is designed such that the at least one storage cell expands when charging and contracts when discharging. In other words, the cooling arrangement is designed so that expansion and contraction of the storage cell during charging and discharging is possible even when the cooling chamber is circulated by coolant. The coolant pressure, which is adjustable by means of the pressure control device in the cooling chamber and is set during operation, is therefore dimensioned such that expansion and subsequent contraction of the storage cells are still possible. This is particularly advantageous for the service life of the at least one storage cell.Furthermore, the volume expansion tank arrangement is preferably designed to absorb a volume of coolant displaced from the cooling chamber when the storage cell expands, particularly into the cavity of the structural component, and to release at least a portion of the absorbed coolant volume back into the cooling chamber when the storage cell deflates. If, for example, the storage cell does not return to its original minimum volume during deflating, a portion of the coolant volume absorbed into the cavity may remain there. It is also possible that, after the coolant volume has been absorbed into the cavity, the coolant pressure in the cooling chamber should be reduced, at least temporarily, so that when the cells deflate, only a portion of the absorbed coolant volume is returned to the cooling chamber to provide this pressure reduction.

[0022] The swelling of a battery cell during charging and the corresponding shrinkage during discharging is also known as charge-induced swelling. The volumetric compensation tank arrangement is primarily designed and intended to compensate for this charge-induced swelling of the battery cell. This allows the battery cell to cyclically expand and contract without affecting the coolant pressure in the cooling chamber, as excess volume can be absorbed by the volumetric compensation tank arrangement and subsequently returned. This also advantageously allows the pressure setting in the cooling chamber to be decoupled from the volume compensation during the swelling of the at least one battery cell.

[0023] The fact that the memory cell expands during charging means that its volume increases when charging and decreases when discharging, although it doesn't necessarily have to return to its minimum initial volume before charging. In particular, the memory cell's volume also increases over its lifetime, a phenomenon known as aging swelling. This swelling can therefore be superimposed on an irreversible component, resulting in a certain degree of irreversible volume increase.

[0024] According to a further advantageous embodiment of the invention, the volume expansion tank arrangement is designed with a passive balancing mechanism. In other words, no active control of the volume expansion tank arrangement or any part thereof is required in order for the coolant volume to be absorbed by the volume expansion tank arrangement when the at least one battery cell swells and returned to the cooling chamber when the cell swells. This makes the volume expansion tank arrangement particularly simple and efficient. A passive pressure-dependent balancing mechanism is advantageous in this context, as will be explained in more detail below.

[0025] According to a further advantageous embodiment of the invention, the volume expansion tank arrangement comprises an expansion tank designed to provide a receiving area for receiving the coolant volume, and a movable element that delimits the receiving area. The volume expansion tank arrangement is designed such that coolant volume can be received into the receiving area by moving the movable element, and in particular, a specific restoring force can be exerted on the coolant volume by the movable element receiving the coolant volume into the receiving area. The expansion tank can be provided by the aforementioned structural component. In particular, the receiving area of ​​the expansion tank can be provided by at least a portion of the cavity of the structural component. The movable element can, for example, be integrated into the cavity of the structural component.By incorporating a movable element, it is advantageously possible to direct the displaced coolant volume into the receiving area while simultaneously generating a specific restoring force through this movable element. This allows for a particularly simple implementation of a passive balancing mechanism.

[0026] According to a further advantageous embodiment of the invention, the movable element is designed as a flexible and / or elastic membrane, wherein the expansion tank comprises a sealed volume filled with a fluid, which is separated from the receiving area by the membrane. The fluid, which is preferably a gas, has a higher compressibility than the coolant, and the restoring force can be generated by compression of the fluid as it is absorbed into the receiving area. In the simplest case, the fluid can be air. The volume filled with the fluid is preferably sealed gas-tight. This allows a kind of air cushion to be enclosed in this volume. If the storage cell expands in the cooling chamber, the coolant pressure in the cooling chamber initially increases.This pressure increase causes the membrane to expand towards the volume filled with fluid, as this fluid has a higher compressibility than the coolant. The fluid pressure rises accordingly until it and the coolant pressure in the cooling chamber are in equilibrium. The pressure increase of the coolant in the cooling chamber, due to the expansion of at least one storage cell, therefore follows the ideal gas law. The "excess" volume can thus be collected in a pressure expansion tank, i.e., the expansion tank of the volume-expansion tank arrangement, similar to, for example, a pressure expansion tank in a heating system. A defined volume of gas can be separated from the cooling fluid, i.e., the coolant, for example, by a membrane, such as an elastomer membrane, or a "back-in-box" system.The desired or accepted pressure increase in the cooling system due to the charge-induced swelling of the at least one storage cell depends on the volume of gas used. In other words, the sealed volume filled with the fluid, and especially the initial pressure of this fluid when the membrane is, for example, at one of its defined zero positions, determines how much the pressure in the cooling chamber increases with a specific volume increase of the cells. This sealed volume of the expansion tank and the initial pressure thus determine how much the coolant pressure rises and falls in the cooling chamber during the swelling of the at least one storage cell.

[0027] The movement of a movable element can therefore also be understood as the movement of only parts of such a movable element, while other parts or sections of the movable element remain stationary. In the case of an elastic or flexible membrane, an increasing bulging or swelling of the membrane in a certain direction as the storage cell swells and / or a convex bulging of the membrane that decreases again as the storage cell swells can thus also be considered such movement.

[0028] According to a further advantageous embodiment of the invention, the expansion tank comprises a cylinder, and the movable element is designed as a piston movable in the cylinder, which is coupled to a restoring device generating the restoring force, in particular comprising a spring.

[0029] In this example, the piston as a whole moves translationally when the storage cell expands or contracts. The coolant pressure generated in the cooling chamber as the storage cell expands leads to increasing pressure on the piston, which moves it within the cylinder and thereby enlarges the receiving area of ​​the expansion tank, where the coolant is stored. As the receiving area increases and the piston moves accordingly, the restoring force exerted by the return mechanism, which may include a spring, also increases. When the storage cell contracts again, the coolant pressure on the piston decreases, causing it to return to its initial position within the cylinder due to the restoring force.

[0030] The return mechanism can also be designed differently than with a spring. For example, it can also include a fluid cushion or air cushion that is compressed by the movement of the piston. The return mechanism can also be pneumatic and / or hydraulic.

[0031] In this example, the excess coolant volume displaced from the cooling chamber when the storage cell expands can be collected in a pressure equalization tank, similar to a spring-loaded hydraulic cylinder. The pressure increase in the cooling system, that is, at least within the cooling chamber, due to charge-induced swelling depends, in this example, on the type of spring used, particularly a coil spring, and follows the spring constant. With a sufficiently flat spring characteristic, minimal pressure increases due to charge-induced swelling can be achieved. In other words, when the storage cell expands, the pressure in the cooling chamber increases only slightly if a spring with a low spring constant, i.e., a soft spring, is used.The maximum permissible pressure increase in the cooling chamber can therefore be easily dimensioned by selecting the spring or spring system and its spring constant.

[0032] Overall, the expansion tank arrangement can be designed such that the coolant pressure in the cooling chamber increases with the increasing volume of coolant absorbed by the expansion tank. However, this increase in coolant pressure can be limited by an upper threshold. By appropriately selecting and dimensioning the return mechanisms, for example, the volume and pressure of the fluid absorbed in the aforementioned volume or the spring constant, it can be easily ensured that the coolant pressure in the cooling chamber does not exceed this limit despite the pressure increase.

[0033] It is also advantageous if a slight pressure increase in the cooling chamber is permissible and does not require compensation, as this greatly simplifies the system design. Nevertheless, it is also possible and conceivable to design the expansion tank arrangement in such a way that the coolant pressure in the cooling chamber remains essentially constant as the coolant volume in the expansion tank increases. For this purpose, an additional expansion tank can be used, as explained in more detail below.

[0034] Therefore, a further advantageous embodiment of the invention is provided that the cooling arrangement includes a second expansion tank which is coupled to the cooling circuit via at least one coupling path comprising a pump and / or a valve, in particular a pressure regulating valve. It can be provided, in particular, that this second expansion tank is coupled to the cooling circuit via two coupling paths, one of which comprises the pump and the other the valve, in particular the pressure regulating valve. This can be designed as a passively pressure-dependent valve or as an actively controllable valve. For example, coolant from the cooling circuit, in particular from the cooling chamber, can be introduced into the second expansion tank via the valve, for example, from a certain pressure threshold or when the coolant pressure reaches or exceeds this pressure threshold.If this pressure threshold, or a second pressure threshold, is undershot, coolant can be pumped back into the cooling circuit. This allows for easy regulation to a specific, predetermined pressure in the coolant circuit. To easily regulate and adjust different pressures, it is advantageous for the valve, particularly the pressure regulating valve, to be designed as a controllable valve. A control unit can be provided for this purpose. This valve, as well as optionally the pump, the expansion tank, and the control unit, can be part of the aforementioned pressure regulating system. Additionally or alternatively, the expansion tank assembly can also be part of the pressure regulating system.The threshold at which coolant is directed into the second expansion tank can be higher than the pressure fluctuations in the cooling chamber that occur during charge-induced swelling of the storage cell. The valve can also be activated periodically to draw coolant into the second expansion tank to compensate for age-related swelling of at least one storage cell. As described above, the charge-induced swelling of a storage cell is superimposed by an age-related, irreversible swelling component. Therefore, the volume of the storage cell increases continuously on average over its service life.To prevent the absorption volume of the first expansion tank of the volume expansion tank arrangement from reaching its limits in order to compensate for this, it is advantageous to absorb coolant into the second expansion tank from time to time, in particular at least partially irreversibly, in order to ensure the functionality of the volume expansion tank arrangement over its lifetime.

[0035] Furthermore, the provision of the additional second expansion tank allows for more flexible and even more customized active control of the coolant pressure in the cooling compartment.

[0036] When such a pressure threshold is exceeded, the valve opens, for example, passively or actively through actuation. The fill level in the first expansion tank can be reduced by opening this valve. The second expansion tank can thus be advantageously used, in particular additionally, to accommodate the coolant component irreversibly displaced over the lifetime of the storage cell.

[0037] According to a further highly advantageous embodiment of the invention, the second expansion tank comprises a maximum receiving volume that is smaller than a second coolant volume displaced from the cooling chamber over a lifetime by irreversible swelling of the at least one storage cell, and at least as large as a third coolant volume displaced from the cooling chamber by irreversible swelling of the at least one storage cell within a predetermined maintenance interval, wherein the cooling arrangement comprises a control device designed to output information or a warning to empty the second expansion tank according to a predetermined criterion.

[0038] This particularly advantageous embodiment of the invention is based on the understanding that a storage cell expands irreversibly over its lifetime to such an extent that, considering an average high-voltage battery with a corresponding number of storage cells, an enormous volume of coolant would be displaced over the lifetime of these storage cells, for example, in the range of approximately 20 liters or more. To compensate for this, a correspondingly large second expansion tank would be required, which in turn would consume a considerable amount of installation space. Therefore, it is now very advantageous to design the second expansion tank to be smaller with regard to its maximum capacity and instead empty it at predetermined maintenance intervals.Such a maintenance interval can, for example, define a predetermined time period, a predetermined distance driven by the vehicle, a predetermined number of charging cycles, or similar parameters. This allows the second expansion tank to be significantly smaller, as it only needs to be designed to hold the excess coolant for such a predetermined maintenance interval, which is considerably shorter than the lifespan of the battery cell. The control unit can also be configured to issue a warning or notification when the second expansion tank needs emptying. Such a warning can be issued, for example, when a certain fill level in the second expansion tank is reached or exceeded, which can be detected by a suitable sensor in the expansion tank, such as a level sensor.Such a warning or information can also be issued simply when the predetermined maintenance interval has been reached, is about to be reached, or has already been reached, without any maintenance and / or emptying of the second expansion tank having taken place. Other criteria or control parameters are also conceivable, depending on which such a warning can be issued.

[0039] Alternatively or additionally, it is also conceivable that this second expansion tank, analogous to the first expansion tank described, is integrated into a structural component of the vehicle that is at least partially formed with a cavity. This could be the same structural component into which the first expansion tank is integrated, or a different one. The structural component can be designed as previously described in relation to the control command, for example, as a body structural component and / or a support and / or a frame, in particular as part of an energy storage housing.

[0040] Furthermore, the invention also relates to a motor vehicle and / or a stationary energy storage arrangement with a cooling arrangement according to the invention or one of its embodiments.

[0041] The motor vehicle according to the invention is preferably designed as a motor vehicle, in particular as a passenger car or truck, or as a passenger bus or motorcycle.

[0042] Furthermore, the invention also relates to a method for operating a cooling arrangement for a motor vehicle, which comprises an energy storage device with at least one storage cell, a cooling circuit through which a coolant flows, a cooling chamber through which the coolant flows and in which at least part of the storage cell is arranged, and a pressure regulating device that sets a specific coolant pressure in the cooling chamber. The cooling arrangement is designed such that, when the storage cell expands, the coolant volume displaced from the cooling chamber is absorbed into a cavity of a structural component that is fluidically coupled to the cooling chamber.

[0043] The advantages described for the cooling arrangement according to the invention and its embodiments apply equally to the method according to the invention.

[0044] The invention also includes further developments of the method according to the invention, which have features already described in connection with the further developments of the cooling arrangement according to the invention. For this reason, the corresponding further developments of the method according to the invention are not described again here.

[0045] The invention also includes combinations of the features of the described embodiments. The invention therefore also includes realizations that each exhibit a combination of the features of several of the described embodiments, provided that the embodiments have not been described as mutually exclusive.

[0046] The following are exemplary embodiments of the invention described. This is illustrated by: Fig. 1 a schematic representation of a cooling arrangement according to an embodiment of the invention; and Fig. 2 a schematic representation of a further variant of an expansion tank for a cooling arrangement according to an embodiment of the invention.

[0047] The exemplary embodiments described below are preferred embodiments of the invention. In these exemplary embodiments, the described components each represent individual features of the invention, which can be considered independently of one another and each further develops the invention independently. Therefore, the disclosure is intended to include combinations of features of the embodiments other than those shown. Furthermore, the described embodiments can also be supplemented by further features of the invention already described.

[0048] In the figures, identical reference symbols denote functionally equivalent elements.

[0049] Fig. Figure 1 shows a schematic representation of a cooling arrangement 10 according to an embodiment of the invention. The cooling arrangement 10 comprises an energy storage device 12 with at least one storage cell 14, and in this case several storage cells 14, which are hereinafter also referred to as battery cells 14. Furthermore, the cooling arrangement 10 includes a cooling circuit 18 through which a coolant 16 flows, and which comprises a cooling chamber 20 through which the coolant 16 also flows. The battery cells 14 are arranged within the cooling chamber 20, in particular each completely. It can also be provided that only a portion of the respective battery cells 14 are arranged within this cooling chamber 20. This advantageously provides immersion cooling. The cell housings 22 of the respective cells 14 are thus directly exposed to and around the coolant 16 and can be physically contacted.The cooling arrangement 10 also includes a pressure regulating device 24 for setting a specific coolant pressure p of the coolant 16 in the cooling chamber 20 when the coolant 16 flows through it.

[0050] To circulate the coolant 16 in the cooling circuit 18, the circuit may also include a coolant pump 26. For pressure control, the pressure control device 24 may also include a pressure sensor 28, which in this example is located on the inlet side of the cooling chamber 20 with respect to the flow direction of the coolant 16, illustrated by the arrows 30.

[0051] The cooling chamber 20 can be bounded by walls 32, which can simultaneously provide a housing 34, for example a module housing or battery housing 34 for the energy storage device 12. However, the energy storage device 12 can also comprise a separate housing that encloses the cooling chamber 20 including its walls 32, although this is not explicitly shown here.

[0052] Furthermore, the cooling circuit 18 can be thermally coupled to another cooling circuit 36 ​​of the vehicle, in which the cooling arrangement 10 is used. This thermal coupling can be achieved, for example, via a heat exchanger 38. This allows the cooling arrangement 10 to be pressure-decoupled from this other cooling circuit 36, making it possible to provide significantly higher pressures p in the cooling arrangement 10 than, for example, in the other cooling circuit 36. This allows for the advantageous implementation of pressure cooling, particularly for the energy storage device 12, and especially its battery cells 14.

[0053] This allows the cells 14 to be subjected to a defined and, above all, very uniform pressure p via the coolant 16. This is beneficial for the service life of the battery cells 14, and optionally eliminates the need for additional cell separators between the cells 14 and / or bracing between the cells 14. This allows for the elimination of numerous components and, at the same time, provides significantly more efficient cooling and temperature control of the cells 14 in general.

[0054] If, on the other hand, the cooling arrangement 10 is designed such that the coolant pressure p in the cooling circuit 18 does not have an increased pressure level compared to the further cooling circuit 36, the respective cooling circuits 18, 36 can also be fluidically coupled to each other, which is to be illustrated by the dashed double arrow 39.

[0055] Cells 14 continue to undergo charge-induced swelling. This means that when cells 14 are charged, i.e., when their state of charge increases, they swell or expand, and their volume increases accordingly. When cells 14 are discharged, i.e., when their state of charge decreases, they swell again, meaning their volume decreases. This charge-induced swelling of cells 14 can be superimposed by an age-related, irreversible swelling. This means that as cells 14 age, their average volume increases.

[0056] This charge-induced swelling leads to a cyclical displacement of coolant 16 from the cooling chamber 20. This can now advantageously be compensated for or absorbed by a volume expansion tank arrangement 40.

[0057] This volume expansion vessel arrangement 40 comprises, firstly, a first expansion vessel 42, which can accommodate the coolant volume 16V displaced during the swelling of the cells 14. The area of ​​the vessel 42 in which this displaced coolant volume 16V can be accommodated can also be referred to as the receiving area 44. When the cells 14 swell again, the absorbed coolant volume 16V can be returned, at least partially or completely, to the coolant circuit 18 and, in particular, to the cooling chamber 20. By providing this volume expansion vessel arrangement 40, the coolant pressure p can advantageously be kept essentially constant or at least below a predefinable threshold value, and thus within a predefinable pressure range that is very advantageous for the cells 14.

[0058] The receiving area 44 of the first expansion tank 42 can, for example, be designed to receive a coolant volume between 0.1 liters and 5 liters, in particular preferably less than 2 liters, for example for a volume between 0.5 liters and 1 liter.

[0059] It is particularly advantageous if the cooling arrangement 10 comprises a structural component 48 that is at least partially formed with a cavity 46, for example, a body structure component and / or a support, or, as in this example, a frame part 50 of a frame for a battery housing, e.g., the battery housing 34 shown, or, if the housing 34 is designed as a module housing, the frame part can also be part of a complete battery housing. At least a part of the volume expansion tank arrangement 40 can be integrated into this structural component 48, in particular into its cavity 46. In this example, this cavity 46 can be used, for example, to provide the receiving area 44 or, more generally, the interior of the first expansion tank 42. In particular, the wall of the expansion tank 42 can simultaneously be provided by this structural component 48.This makes it advantageous to use otherwise unused hollow volumes within the motor vehicle in order to integrate the functionality of an expansion tank 42 into them.

[0060] The expansion tank 42, or the volume expansion tank assembly 40, can be designed in a variety of ways. For example, the volume expansion tank assembly 40 can have a movable element 52, which in this example is designed as an elastic membrane 54. Furthermore, in this example, the expansion tank 42 includes an inlet opening 56, which is fluidically connected to the cooling circuit 18, or rather to the circulation path in which the coolant 16 of the cooling circuit 18 circulates, via a coupling path 58. This path is designated 60. The inlet opening 56 is fluidically connected to the receiving area 44. In this example, the membrane 54 separates the receiving area 44 from a volume 45 filled with a fluid F, which can also be provided as part of the cavity 46. The volume 45 can be hermetically sealed, in particular gas-tight.The fluid F is preferably a gas, for example, air. As the cells 14 expand during swelling, the coolant volume 16V is forced into the receiving area 44, causing the membrane 54 to expand and thus compressing the fluid F in volume 45. This generates a restoring force R, which, when the cells 14 de-swell, causes the membrane 54 to retract or move back towards the outlet 56, thereby returning at least part of the absorbed coolant volume 16V to the cooling circuit 18.

[0061] Fig. Figure 2 shows a schematic representation of the volume expansion tank arrangement 40 as part of the pressure regulating device 24 according to a further embodiment of the invention. This also comprises a first expansion tank 42, which is provided by a structural component 48, for example, a housing frame 50 of a battery housing 34. In this example, the expansion tank 42 provides a cylinder 62 in which a piston 64 is arranged to be translationally movable. The piston 64 represents a further example of the previously mentioned movable element 52. The piston 64 is again coupled to a return mechanism 66 for generating a return force R, which in this example comprises a spring 68, in particular a coil spring.As the displaced coolant volume 16V flows into the receiving area 44 of the expansion tank 42, the piston 64 is moved upwards due to pressure in this example, i.e., against the restoring force R generated by the restoring device 66, thereby increasing the restoring force R according to the spring constant of the spring 68. When the cells 14 deflate, the reduction in volume of the cells 14 in the cooling chamber 20 results in a corresponding pressure drop, causing the piston 64 to move towards the outlet opening 56 due to the restoring force R, and the absorbed coolant volume 16V is returned, at least partially, to the cooling circuit 18.

[0062] Furthermore, numerous other variations for the design of such a volume-compensating reservoir arrangement 40 are conceivable. The volume and the outlet pressure of the Fig. 1 described in volume 45, fluid F absorbed, and by the spring stiffness of the spring 68 of the return device 66 according to Fig. 2. The pressure increase when the excess coolant volume 16V is absorbed into the expansion tank 42 can be adjusted or dimensioned as desired. This makes it possible, for example, to ensure that the swelling of the cells 14 only leads to a slight pressure increase in the cooling chamber 20.

[0063] Furthermore, in this example, the cooling arrangement 10 includes a second expansion tank 70, which is connected to the cooling circuit 18 via a first coolant path 72 with a valve 74, in particular a pressure regulating valve 74, and via a second coolant path 76 with a pump 78. The pump 78 and / or the valve 74 can be controlled by a control unit 80 as part of the cooling arrangement 10, which is shown here purely as an example. These components can also be considered part of the pressure regulating device 24. In the event of an excessive pressure increase in the cooling circuit 18, the valve 74 can be opened, allowing coolant 16 to enter the second expansion tank 70. If a pressure drop occurs in the cooling system 18, for example below a predetermined threshold, coolant can be pumped from the second expansion tank 70 back into the cooling circuit 18 by means of the pump 78.The control of these components 74, 78 can be based on various parameters, such as the aging state of the cells 14 or the energy storage device 12, the temperature, the state of charge of the energy storage device 12, the operating state of the energy storage device 12, or similar factors. In particular, excess coolant 16 resulting from age-related swelling of the cells 14 can also be absorbed by means of the second expansion tank 70. The tank 70 does not need to be particularly large for this purpose, but can, for example, be designed to absorb excess coolant 16 for a defined maintenance interval.By regularly emptying the coolant reservoir 70, its volume can be extremely small, for example in the range of a few liters or even just a single liter, and yet the excess coolant volume resulting from the age-related swelling of the cells 14 can be efficiently absorbed and removed, thereby also compensating for the age-related swelling.

[0064] The second expansion tank 70 can also be incorporated into or provided by a structural component 48'. This can again be a frame 50' of a battery housing 34, for example another frame section of such a housing 34, or any other structural component 48'.

[0065] Overall, the examples demonstrate how the invention provides an optimized expansion tank for charge-induced swelling. Advantageously, the invention makes it possible to compensate for volume changes caused by charge-induced swelling using a space-optimized pressure expansion tank. Ideally, the pressure increase in the cooling system should not exceed a defined value to prevent accelerated cell aging or cooling system rupture. The described measures limit the pressure increase in the cooling system to a defined value, leading to an increase in battery lifespan. This minimizes cell aging effects and maximizes performance. Furthermore, the size of the expansion tank can be minimized by integrating it into the battery frame, saving space, costs, and weight. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2018 215 477 A1

[0002] DE 10 2020 118 542 B3

[0004] DE 10 2022 109 173 A1

[0005]

Claims

[1] Cooling arrangement (10) for a motor vehicle, wherein the cooling arrangement (10) has - an energy storage device (12) with at least one storage cell (14), - a cooling circuit (18) through which a coolant (16) flows, with a cooling chamber (20) through which the coolant (16) flows, in which at least a part of the storage cell (14) is arranged, - a pressure regulating device (24) for setting a specific coolant pressure (p) in the cooling chamber (20) when the coolant (16) flows through it, characterized by , that the cooling arrangement (10) comprises a structural component (48) which is at least partially formed with a cavity (46), and has a volume compensation tank arrangement (40) which is at least partially provided by the structural component (48) and its cavity (46), which is fluidically coupled or can be coupled to the cooling space (20). [2] Cooling arrangement (10) according to claim 1, characterized by, that the structural component (48) represents a body structure and / or a support or frame (50), in particular as part of a housing (34) of the energy storage device (12). [3] Cooling arrangement (10) according to one of the preceding claims, characterized by , that the cooling arrangement (10) is designed such that the storage cell (14) expands when the storage cell (14) is charged and shrinks when the storage cell (14) is discharged, wherein the volume compensation vessel arrangement (40) is designed to receive a volume of coolant (16V) displaced from the cooling chamber (20) when the storage cell (14) expands, in particular into the cavity (46), and to release at least a part of the received volume of coolant (16V) into the cooling chamber (20) when the storage cell (14) shrinks. [4] Cooling arrangement (10) according to one of the preceding claims, characterized by, that the volume compensation tank arrangement (40) is designed with a passive compensation mechanism. [5] Cooling arrangement (10) according to one of the preceding claims, characterized by , that the volume expansion tank arrangement (40) has an expansion tank (42) designed to provide a receiving area (44) for receiving the coolant volume (16V), and has a movable element (52; 54, 64) that limits the receiving area (44), wherein the volume expansion tank arrangement (40) is designed such that the coolant volume (16V) can be received into the receiving area (44) by moving the movable element (52; 54, 64), in particular wherein a certain restoring force (R) can be exerted on the coolant volume (16V) by receiving the coolant volume (16V) into the receiving area (44) by the movable element (52; 54, 64). [6] Cooling arrangement (10) according to one of the preceding claims, characterized by, that the movable element (52; 54, 64) is designed as a flexible and / or elastic membrane (54), wherein the expansion vessel (42) comprises a closed volume (45) filled with a fluid (F) which is separated from the receiving area (44) by the membrane (54), wherein the fluid (F), which is in particular a gas (F), has a higher compressibility than the coolant (16), wherein the restoring force (R) can be generated by a compression of the fluid (F) during the absorption of the coolant volume (16V) into the receiving area (44). [7] Cooling arrangement (10) according to one of the preceding claims, characterized by, that the expansion tank (42) comprises a cylinder (62), and the movable element (52; 64) is designed as a plunger (64) movable in the cylinder (62), which is coupled to a restoring device (66) generating the restoring force (R), in particular comprising a spring (68). [8] Cooling arrangement (10) according to one of the preceding claims, characterized by , that the cooling arrangement (10) has a second expansion tank (70) which is coupled to the cooling circuit (18) via at least one coupling path (72, 76) which has a pump (78) and / or a valve (74), in particular a pressure regulating valve. [9] Cooling arrangement (10) according to one of the preceding claims, characterized by, that the second expansion tank (70) comprises a maximum receiving volume which is less than a second coolant volume displaced from the cooling chamber (20) over a lifetime by irreversible swelling of the storage cell (14), and is at least as large as a third coolant volume displaced from the cooling chamber (20) by irreversible swelling of the storage cell (14) within a predetermined maintenance interval, wherein the cooling arrangement (10) comprises a control device (80) which is designed to output information or a warning to empty the second expansion tank (70) according to a predetermined criterion. [10] Method for operating a cooling arrangement (10) for a motor vehicle, which - an energy storage device (12) with at least one storage cell (14), - a cooling circuit (18) through which a coolant (16) flows, with a cooling chamber (20) through which the coolant (16) flows, in which at least a part of the storage cell (14) is arranged, and - has a pressure regulating device (24) that sets a specific coolant pressure (p) in the cooling chamber (20), characterized by , that the cooling arrangement (10) is designed such that when the storage cell (14) expands, the coolant volume (16V) displaced from the cooling chamber (20) is absorbed into a cavity (46) of a structural component (48) which is fluidically coupled to the cooling chamber (20).

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