COOLING DEVICE FOR A VEHICLE TRANSACTION BATTERY

Description

[0001] The present invention relates to a cooling device according to the preamble of claim 1. Such a cooling device is known from WO2019 / 039187.

[0002] The present invention also relates to an electrically powered vehicle with a traction battery and the above-mentioned cooling device.

[0003] Various types of high-performance batteries are known from the current state of the art. In such high-performance batteries, like those used as traction batteries in electric vehicles, high power outputs are achieved during charging and discharging. These batteries can currently operate at voltages of up to several hundred volts or even up to 1000 volts. Furthermore, charging and discharging currents of several hundred amperes up to 1000 amperes are currently possible. In principle, even higher voltages and currents are possible in future developments.

[0004] In high-performance batteries, the large charging and discharging currents cause significant thermal losses, leading to heating of the batteries. To protect the batteries from thermal damage and achieve high efficiency, it is crucial to maintain the high-performance battery within a desired temperature range. To prevent exceeding this temperature range, heat must be dissipated from the batteries. This becomes increasingly important as the currents and associated thermal losses increase, ensuring the batteries remain within the desired temperature range even under such high currents. Current lithium-ion battery cells operate most effectively within a narrow temperature range, for example, 15° to 40°C, with high temperature homogeneity and a temperature variation of only 2 to 4°C within and between the battery cells.Under such conditions, safe operation of the high-performance batteries and a long service life with consistent performance can be achieved.

[0005] To ensure these conditions and avoid exceeding the temperature range, battery cells from current high-performance batteries are operated under specific conditions. dhDuring charging and / or discharging, the battery is cooled. Various cooling methods are currently used. For example, liquid cooling can be achieved with a heat exchanger through which a liquid heat transfer medium flows. The heat exchanger is usually located beneath the battery cells, where it is thermally connected to them via a contact heat transfer. The heat capacity of the liquid heat transfer medium is used to absorb heat emitted by the battery cells or the battery as a whole via a temperature difference and dissipate it either directly to the environment or via a cooling circuit. Water or an electrically conductive water-glycol mixture, for example, is used as the heat transfer medium, which is why reliable separation of the heat transfer medium from the battery cells is necessary.

[0006] A similar cooling effect can also be achieved using air as the heat transfer medium. Since air, unlike water, is not electrically conductive, the battery cells can be in direct contact with the heat transfer medium and, for example, be surrounded by it. A heat exchanger is therefore not strictly necessary.

[0007] In currently available systems, the heat transfer medium is actively circulated to dissipate the released heat through convection. In active circulation, the heat transfer medium is actively circulated to remove heat from the battery cells.

[0008] As a further development of liquid cooling with a heat exchanger in contact with the battery cells, the liquid heat transfer medium can be evaporated by absorbing heat from the heat exchanger. This leads to higher heat transfer rates and, due to the enthalpy of vaporization, to a high heat absorption rate per unit mass of the heat transfer medium. After condensation, the heat transfer medium can be returned to the heat exchanger in its liquid state.

[0009] Systems for cooling with a liquid heat transfer medium are also under development, for example, in industrial applications for high-voltage traction batteries, which eliminate the need for a heat exchanger in contact with the battery cells. Similar to using air as a heat transfer medium, cooling occurs through direct flow of the liquid heat transfer medium around the components to be cooled. An important property of the liquid heat transfer medium is therefore its dielectricity, since the heat transfer medium is in direct contact with the battery cells, i.e., with electrically conductive and potential-carrying components. Furthermore, the enthalpy of vaporization and the associated high heat transfer can also be utilized in the dielectric liquid heat transfer medium if the heat transfer medium evaporates during the heat transfer process due to the heat input from the battery cells being cooled.This type of cooling is called two-phase immersion cooling.

[0010] In such systems with active circulation, both weight and energy consumption are increased due to additional components such as compressors or pumps. Furthermore, in the event of a power failure in the vehicle, the battery cells are not cooled, which is particularly problematic in conjunction with a previously high power output and can lead to heat buildup.

[0011] The present invention is based on the objective of providing a cooling device for cooling a traction battery of a vehicle with a fluid, as well as a vehicle with such a cooling device, which enables efficient cooling of the battery cells of the traction battery with low weight and high reliability.

[0012] The problem underlying the present invention is solved by a cooling device having the features of claim 1. Advantageous embodiments of the cooling device are described in claims 2 to 10, which depend on claim 1.

[0013] In more detail, the problem underlying the present invention is solved by a cooling device for cooling a traction battery of a vehicle with a fluid, comprising an evaporation device for installation in a housing body of the traction battery, at least one condensation device for installation on the vehicle outside the housing body of the traction battery, and connecting lines that convey fluid evaporated in the evaporation device to the at least one condensation device and condensed fluid from the at least one condensation device back to the evaporation device.

[0014] The cooling device according to the invention is characterized in that the evaporation device, the at least one condensation device and the connecting lines form a first cooling circuit, and the first cooling circuit is designed according to the nature of natural circulation, wherein a circulation of the fluid through the first cooling circuit comprises a transport of gaseous fluid from the evaporation device to the at least one condensation device and of liquid fluid from the at least one condensation device back to the evaporation device, and the circulation in operation is based on density differences between the fluid evaporated in the evaporation device and the fluid condensed in the at least one condensation device and a height difference between the at least one condensation device and the evaporation device.

[0015] The problem underlying the present invention is also achieved by a vehicle with the features of claim 1. 11 Solved. Advantageous embodiments of the vehicle are described in claims 12 to 16, which depend on claim 11.

[0016] In more detail, the problem underlying the present invention is also solved by an electrically powered vehicle with a traction battery and the above cooling device, wherein the traction battery with its housing body and the evaporation device attached therein is located in a floor area of ​​the vehicle, at least one condensation device is located outside the traction battery in an area above the evaporation device, and a fluid is received in the cooling device.

[0017] The cooling device according to the invention thus forms a cooling circuit within the vehicle, in which the fluid circulates passively between the evaporation device and the at least one condensation device without a circulation device. By eliminating the circulation device, the cooling device can be operated virtually maintenance-free, as it does not require active components that could potentially fail, thereby increasing the operational reliability of the traction battery and thus the vehicle. The cooling device according to the invention is also cost-effective and lightweight. The passive cooling circuit eliminates the need for active fluid transport. This has the advantage that the cooling device can be cooled even when the vehicle is not in use.For example, the traction battery can be cooled not only while charging at a charging station, but also after charging is complete, even when the vehicle is not actively in use, such as during driving. This allows any heat remaining in the traction battery after operation, i.e., after charging or driving, to be dissipated.

[0018] In the cooling device according to the invention, passive circulation of the fluid takes place in the first cooling circuit. The cooling device is thus designed in the manner of a thermosiphon. The thermosiphon is a passive construction that enables heat exchange by utilizing natural convection in a vertical fluid circuit between the evaporation device and the at least one condensation device. The function of the thermosiphon is based on a density difference between the liquid and gaseous phases of the fluid. When heat is absorbed from the battery cells of the traction battery, the initially liquid fluid evaporates in the evaporation device. As a result, the gaseous fluid flows in the connecting lines, due to its low density and without a circulation device, to the at least one condensation device, which is arranged above the evaporation device.In the at least one condensing device, the gaseous fluid releases the previously absorbed heat to the surroundings and condenses. From there, the condensed fluid flows back into the housing due to gravity and based on the height difference between the at least one condensing device and the evaporation device, where it is again supplied to the evaporation device. A plenum of liquid fluid is formed in the housing of the traction battery, from which the liquid fluid re-enters the evaporation device.

[0019] When a steam-filled riser and a liquid-filled downpipe are arranged vertically, different pressures exist at the bottom of the two pipes due to the different densities of the steam and liquid columns, respectively. If the riser and downpipe are connected at the bottom, pressure equalization is achieved by the flow of liquid fluid from the downpipe towards the steam column in the riser. As the fluid evaporates and is further heated, the concentration of the gaseous fluid in the evaporation device increases. The continuous evaporation of the liquid fluid at the bottom of the riser or in the evaporation device, combined with the condensation of the gaseous fluid at the top of the riser or in at least one condensation device, and the subsequent return of the condensed fluid to the downpipe, completes the cycle and creates a dynamic circulation within the cooling device.

[0020] Two-phase cooling enables the provision of an efficient cooling system. In this system, the liquid fluid in the evaporation unit absorbs heat from the battery cells, causing it to evaporate. In the at least one condensation unit, it releases this heat to the vehicle's surroundings, causing the gaseous fluid to condense back into a gaseous state. This allows the fluid to circulate within the cooling system in a closed-loop cooling cycle, absorbing heat of vaporization during evaporation and releasing it again when it condenses from its gaseous state. The amount of heat of vaporization is significant, resulting in a high cooling capacity for the system.

[0021] The vaporization device can be integrated into the housing of the traction battery as a separate component. Alternatively, the vaporization device can be permanently installed in the housing.

[0022] At least one condensing device is arranged outside the housing of the traction battery to provide a sufficient height difference to the evaporation device. A single condensing device may be provided. In a cooling device configuration with multiple condensing devices, these can be suitably distributed throughout the vehicle to collectively provide the necessary total capacity for condensing the gaseous fluid. This also facilitates installation on the vehicle, as the condensing devices can be easily adapted to the vehicle's design and utilize available space. Multiple condensing devices are preferably connected in parallel to the evaporation device via parallel connecting lines. In principle, multiple condensing devices can also be arranged in series and connected to the evaporation device.A combination of these is also possible in principle.

[0023] The condensing device typically dissipates the heat absorbed by the gaseous fluid during condensation to the surroundings, i.e., the ambient air. When the vehicle is in motion, its movement usually supplies enough ambient air to ensure sufficient heat dissipation from the condensing device to the environment. This heat dissipation can be improved by actively supplying ambient air, for example, via a ventilation device, and can be ensured even without the vehicle moving. The at least one condensing device is located outside the traction battery housing to ensure adequate cooling by the ambient air. The cooling device may only include one condensing device.In a cooling system with multiple condensing devices, these can be suitably distributed on the vehicle or arranged together to provide the necessary total capacity for condensing the gaseous fluid. Distributed placement of the condensing devices simplifies installation on the vehicle, as they can be easily adapted to the vehicle's design and utilize available space.

[0024] The connecting lines link the evaporation device and the at least one condensation device. In principle, the liquid fluid and the gaseous fluid can also flow, at least partially, through a common connecting line. Advantageously, each condensation device is connected by two connecting lines: a rising line for transporting gaseous fluid to the condensation device and a falling line for the return transport of the liquid fluid. By connecting the evaporation device and the at least one condensation device via the connecting lines, a corresponding fluid circuit is formed as the first cooling circuit to dissipate heat from the battery cells of the traction battery and release it to the environment.

[0025] The battery cells can be mounted individually or as units / blocks / modules with multiple battery cells within the housing of the traction battery. The housing can have suitable mounting positions for this purpose, in which the battery cells are mounted individually, in groups, or as battery modules.

[0026] The evaporation device is a heat exchanger in which heat is transferred from the traction battery cells to the liquid fluid, causing it to evaporate. Such an evaporation device is also known as an evaporator. The condensation device is also a heat exchanger, but it absorbs heat from the gaseous fluid and releases it to the surroundings, causing the gaseous fluid to condense. Such a condensation device is also known as a vapor condenser or liquefier.

[0027] The fluid is a heat transfer medium and preferably has a boiling point of 10°C to 80°C at ambient pressure. Evaporation of the fluid achieves maximum cooling, which is why a low boiling point is advantageous. The boiling point of the fluid is preferably lower than the maximum operating temperature of the battery cells. Because it boils at these temperatures even at ambient pressure, i.e., typically around one bar, passive cooling can be efficiently achieved with the specified cooling device.

[0028] The traction battery is preferably a high-performance battery capable of operating at voltages of up to several hundred volts or even up to 1000 volts, as well as charging and discharging currents of several hundred amperes up to 1000 amperes. In principle, even higher voltages and currents are possible for future developments. To protect the high-performance battery from thermal damage and to achieve high efficiency, the traction battery is maintained within a desired temperature range. Current battery cells in such traction batteries are, for example, manufactured using lithium-ion technology and operate best within a narrow temperature range of, for example, 15° to 40°C with high temperature homogeneity and a temperature variation of 2–4°C within and between the battery cells.

[0029] The vehicle is, in principle, any vehicle with an electric drive. The vehicle can have exclusively an electric drive, or, as a so-called hybrid vehicle, a combination of different drive systems.

[0030] In an advantageous embodiment, the evaporation device is arranged vertically below the at least one condensation device. A natural gradient is ensured between the at least one condensation device and the evaporation device, so that condensed fluid can flow back from the at least one condensation device to the evaporation device by gravity. Furthermore, the evaporated fluid can easily rise from the evaporation device to the at least one condensation device.

[0031] In an advantageous embodiment, the first cooling circuit comprises a plurality of condensing devices, and these condensing devices are designed for distributed mounting on the vehicle, particularly along the vehicle's longitudinal axis, both in front of and behind the evaporator. The plurality of condensing devices allows for a particularly reliable cooling system. Firstly, the overall cooling capacity of the cooling system can be increased with multiple condensing devices. Furthermore, the distributed mounting of the plurality of condensing devices ensures that, for example, regardless of the vehicle's inclination, at least one of the condensing devices is always advantageously positioned relative to the evaporator, thus enabling condensation of the gaseous fluid and a return flow of the condensed fluid to the evaporator.If the condensing devices are installed longitudinally both in front of and behind the evaporating device, i.e., in front of and behind the housing of the traction battery, then even with a greater inclination of the vehicle, such as can occur when driving uphill or downhill, at least one of the condensing devices is positioned with a suitable height difference to the evaporating device in order to ensure operation as a thermosiphon.

[0032] In an advantageous embodiment, at least one condensing device is designed as a chiller for coupling with the vehicle's air conditioning system to dissipate heat from the first cooling circuit via the air conditioning system. The chiller serves as a controllable heat sink, dependent on the operation of the vehicle's air conditioning system. This allows the chiller to operate the cooling device essentially independently of ambient temperatures in the vehicle's vicinity. The chiller allows the cooling capacity of the corresponding condensing device, and thus the cooling capacity of the cooling device in general, to be adjusted during operation. This allows, for example, anticipating an impending load on the traction battery, particularly during fast charging with high currents, by lowering the temperature of the corresponding condensing device.This allows the traction battery to be pre-cooled before the upcoming load, thus reducing the temperature of the battery cells and the fluid before the chiller is applied. Furthermore, the chiller increases the heat dissipation of the at least one condensing device compared to cooling with ambient air, allowing for a smaller size of the at least one condensing device. The condensing device configured as a chiller can be arranged in parallel or in series with at least one other condensing device.

[0033] In an advantageous embodiment, the cooling device comprises a further condensing device and additional connecting hoses to form a second cooling circuit, and the second cooling circuit includes a circulation device for conveying the fluid within the second cooling circuit. The second cooling circuit is a cooling circuit in which active circulation of the fluid takes place via the circulation device. For this purpose, the circulation device can include a compressor, which is arranged in the corresponding additional connecting line between the evaporating device and the further condensing device and conveys gaseous fluid into the further condensing device. In doing so, the gaseous fluid can be compressed, thereby increasing its condensation temperature. Operation in the second cooling circuit can thus be carried out in the manner of a heat pump.Preferably, the second cooling circuit is additionally equipped with an adjustable throttle valve for setting a pressure level, so that heat can be easily dissipated via the further condensing device even at higher ambient temperatures. Alternatively or additionally, the circulation device can include a pump located in the corresponding connecting line, which delivers liquid fluid to the evaporation device. The circulation device allows the flow rate in the second cooling circuit to be adjusted. The second cooling circuit enables efficient cooling of the fluid and thus the battery cells, reducing dependence on ambient conditions, particularly ambient temperature. Furthermore, the overall heat dissipation by the cooling device with the two cooling circuits can be increased.

[0034] In an advantageous embodiment, the second cooling circuit has at least one valve device for fluid separation from or connection to the first cooling circuit. This allows, for example, cooling to be carried out exclusively via the first cooling circuit during normal operation, while the second cooling circuit can be additionally activated as needed. When the valve device is closed, the ingress of gaseous fluid into the second cooling circuit is prevented.

[0035] Additionally or alternatively, the first cooling circuit can have at least one valve device for flow separation from or connection to the first cooling circuit. Thus, the first cooling circuit can also be activated or deactivated by the corresponding valve device, for example, to improve the function of the second cooling circuit. The valve device can also be designed as a changeover valve, allowing the cooling system to be switched between operation with only the first or only the second cooling circuit.

[0036] In an advantageous embodiment, the cooling device includes a collector for collecting liquid fluid, the collector being arranged, in particular, at a connection between the first cooling circuit and the second cooling circuit. The collector serves to hold the liquid fluid. The collector allows for simple coupling of the two cooling circuits. Additionally, the collector can provide a fluid reservoir.

[0037] In an advantageous embodiment, the cooling device includes a control unit configured to detect an impending load on the traction battery, particularly during fast charging, and further configured to pre-cool the traction battery and / or the fluid using the cooling device when an impending load is detected. This allows the battery cells to heat up during a charging or discharging process over an extended period, for example, if the cooling device has a lower cooling capacity than the heat dissipation of the battery cells at maximum current. Such a lower cooling capacity can result from the dimensions of the cooling device and the traction battery, or from fluctuations in ambient conditions, causing the cooling device to temporarily operate at a reduced cooling capacity compared to its maximum.The control can be achieved, for example, by controlling the vehicle's air conditioning system, provided that at least one condensing device is configured as a chiller within the air conditioning system. Alternatively, the control can act on a second cooling circuit as described above. Another alternative is that the control device can supply an increased amount of ambient air to the at least one condensing device from the outside via a fan.

[0038] According to the invention, the evaporation device is designed as an immersion evaporator and comprises at least one evaporation element, wherein microchannels are formed in the at least one evaporation element, or the at least one evaporation element has microchannel structures for forming microchannels together with battery cells of the traction battery, or microchannel structures are formed between a plurality of evaporation elements for forming microchannels between the evaporation elements and together with battery cells of the traction battery, and the evaporation elements are arranged such that liquid fluid evaporates in the microchannels, absorbing heat from the battery cells. In immersion cooling, if the battery cells heat up, the heat generated can be easily transferred to the fluid, for example, by direct contact of the battery cells with the liquid fluid.This enables efficient heat transfer from the battery cells to the fluid. Furthermore, the traction battery can be provided without a separate heat exchanger between the battery cells and the fluid, resulting in a compact and lightweight design. The microchannels facilitate highly effective evaporation of the fluid. As the fluid evaporates within the microchannels, liquid fluid is entrained, thus wetting the internal channels. During operation, the fluid channels can be partially filled with liquid fluid. The liquid fluid does not completely fill the microchannels, but rather, for example, to a maximum of half their capacity, preferably less than 25%. This reduces the amount of liquid fluid in the traction battery and / or the cooling system, thereby reducing the weight of the cooling system and, consequently, the traction battery itself.In principle, it is not necessary for the microchannels to be partially filled with liquid fluid if, for example, the fluid channels are wetted with liquid fluid during operation. For this purpose, a mixture of liquid and gaseous fluid can enter the fluid channels at a lower vertical end or be formed there. When designing the microchannels in the at least one evaporation element, or when designing the at least one evaporation element with microchannel structures for forming microchannels together with the battery cells, the evaporation elements can each be arranged independently of one another, for example, between adjacent battery cells or at their end faces, such as when using prefabricated battery modules with multiple battery cells.In the design of the evaporation device with multiple evaporation elements, wherein microchannel structures for forming microchannels are arranged between the evaporation elements, the evaporation elements are arranged together to form the microchannel structures. The microchannels are formed from these microchannel structures together with the battery cells. Thus, in the latter two cases, the microchannel structures are at least partially open to the battery cells and are closed by the battery cells, forming the microchannels.

[0039] The microchannels have dimensions that allow liquid fluid to flow in from the plenum and evaporated fluid to rise and flow out. The microchannels can have a rectangular, square, trapezoidal, round, or oval cross-section. For example, the microchannels can have a diameter or side length of less than one centimeter, particularly less than five millimeters, such as approximately two millimeters. The microchannels are open at their top so that the evaporated fluid can flow out of them.

[0040] The fluid used in the traction battery, which is contained within the housing, is a dielectric fluid. This dielectric fluid is electrically non-conductive, thus providing electrical insulation for the individual battery cells. For the same reasons, the evaporation elements are also preferably made of an electrically non-conductive material.

[0041] In an advantageous embodiment, the cooling device, in particular at least one condensing device, includes a pressure equalization device for equalizing the pressure between the interior of the cooling device and the external environment. The pressure in the cooling device can vary from a vacuum to a pressure of several bar, depending, for example, on the fluid used. Thus, when a vacuum develops in the cooling device, it can be vented, i.e., a venting gas, for example, a gas mixture such as ambient air or a specifically supplied single gas such as nitrogen, is introduced, thereby increasing the pressure inside. Alternatively or additionally, when a pressure develops, the cooling device can be vented, i.e., a venting gas is released, thereby decreasing the pressure inside.The venting gas is preferably previously absorbed venting gas, although in practice the venting gas also contains gaseous fluid.

[0042] Pressure equalization can offer various advantages for the cooling circuit and the traction battery. For example, a negative pressure that forms in the cooling device, and consequently in the traction battery, can be reduced through ventilation. This prevents critical negative pressures in the cooling device and thus in the traction battery. Accordingly, the requirements for a negative pressure-resistant design of the traction battery housing or the cooling device can be reduced, thereby decreasing its manufacturing complexity. Ventilation can, in principle, occur at any point within the interior of the cooling circuit. The interior is, in principle, any part of the cooling circuit through which the fluid flows and includes the interior of at least one condensing device.

[0043] Venting preferably occurs from the condenser, where gaseous fluid collects for condensation. This allows for the release of vent gas from a previous venting of the cooling circuit. The vent gas typically has a lower boiling point than the fluid. Venting to release the vent gas ensures high efficiency of the cooling circuit and sufficient cooling of the traction battery, preferably with only previously supplied vent gas being released during the venting process. Phase transitions of the fluid in the cooling device can be easily achieved, particularly during condensation, if no other gas, or as few gases as possible, are present in the cooling device besides the gaseous fluid. After venting with the vent gas, the vent gas mixes with the gaseous fluid in the cooling device to form a gas mixture.This inherently impairs heat transfer, particularly in the condensing unit. Accordingly, venting can be carried out via the pressure equalization device by releasing venting gas. Preferably, the venting gas drawn in during the previous venting process is released to increase the concentration of the gaseous fluid in the cooling circuit. However, gaseous fluid or a mixture of gaseous fluid and the venting gas can also be released as the venting gas.

[0044] To control pressure equalization, the pressure equalization device preferably includes a controllable pressure equalization valve. For example, the pressure equalization valve can open when the pressure inside the cooling device falls below a limit pressure, such as 0.8 bar. As the ambient air flows through the pressure equalization device, it is preferably dried by a drying device, such as a replaceable drying cartridge. This minimizes the ingress of moisture into the condensing device and subsequently into the cooling circuit. dh Water, which is usually electrically conductive, means that a mixture of moisture with the fluid has a lower dielectric constant and a higher electrical conductivity than the fluid alone, which can lead to damage to the traction battery through an electrical short circuit.

[0045] Due to the presence of aeration gas in the cooling device, a higher pressure level is reached when the fluid is heated than would be the case with a pure fluid in the cooling device, and the heat transfer in the at least one condensing device is fundamentally impaired. Accordingly, the cooling device can be vented via the pressure equalization device. Preferably, measures are taken to prevent the escape of the gaseous fluid and to increase its concentration within the cooling device. For this purpose, the pressure equalization device can be designed like a chimney, with the pressure equalization valve located at its upper end. Within the chimney, a separation of gases occurs due to the density difference between the gaseous fluid and the other gases, particularly the ambient air that was previously drawn in.Alternatively or additionally, the pressure equalization device comprises a filter assembly consisting of an activated carbon filter, a zeolite material, a filter membrane, a chemical filter, or any combination of several of these filter elements. The zeolite material is preferably designed to exhibit higher adsorption of the gaseous fluid at a maximum pressure in the cooling device and a corresponding system temperature than at a minimum pressure and corresponding system temperature. To further enhance this, the zeolite material can be actively temperature-controlled during venting. The membrane filter retains the gaseous fluid from the gas mixture due to differing molecular sizes during venting of the interior.The remaining venting gas is typically ambient air with its main components N₂ and O₂ in small molecular sizes, meaning a small particle size compared to a molecular fluid with a complex molecular structure. This allows the remaining venting gas to pass through the membrane filter, retaining only the gaseous fluid. Such a membrane filter specifically has a pore structure through which the venting gas can pass, but not the gaseous fluid. The chemical filter filters the fluid by adsorption.

[0046] The filter unit is preferably discharged during operation by actively supplying heat, thereby recovering the fluid it has absorbed. Alternatively or additionally, the venting gas can be actively cooled during venting, causing the gaseous fluid it contains to condense and only remaining ambient air to escape. The condensed fluid can then be returned in liquid form from the pressure equalization device to the first cooling circuit, resulting in minimal fluid losses when venting the cooling system. Preferably, the pressure equalization device is located in an A-pillar or a C-pillar of the vehicle, i.e., at the front or rear end of the passenger compartment.

[0047] In an advantageous embodiment, the traction battery, with its housing and the vaporization device mounted therein, is arranged below the passenger compartment of the vehicle, preferably between the front and rear axles. This allows the traction battery to be mounted in a particularly low position on the vehicle. Due to the typically high weight of the traction battery, the vehicle can also be provided with a low center of gravity, thereby improving its handling characteristics. Furthermore, arranging the traction battery between the front and rear axles also results in the vehicle having a longitudinally centered center of gravity.

[0048] In an advantageous embodiment, the at least one condensing device is located in an area above a rear axle of the vehicle, particularly above the rear axle wheel arches. By locating it in this area above the rear axle, a suitable height difference between the evaporation device and the at least one condensing device can typically be achieved to facilitate passive circulation of the fluid within the cooling device. Furthermore, locating the at least one condensing device in this area allows for easy supply of ambient air to cool the at least one condensing device and to dissipate heat.Particularly while driving, the resulting airflow from the ambient air can be easily directed to the at least one condensing device to ventilate it and ensure effective cooling. For example, the ambient air can be directed to the at least one condensing device via the wheel wells. In this area, the at least one condensing device is mounted longitudinally along the vehicle as close as possible to the traction battery, so that even when the vehicle is tilted, a sufficient height difference between the evaporating device and the at least one condensing device is maintained.Thus, in typical vehicles, with such an installation of at least one condensing device, even at an inclination of, for example, 18°, a minimum height difference between a liquid level of the fluid in the evaporation device in the housing body and the at least one condensing device can still be achieved, so that the function of the cooling device as a thermosiphon is ensured.

[0049] In an advantageous embodiment, the at least one condensing device is located in an area above the front axle of the vehicle, particularly above the wheel arches of the front axle, preferably at the windshield-side end of the vehicle's hood. In this case as well, the location above the front axle typically allows for a suitable height difference between the evaporation device and the at least one condensing device to achieve passive circulation of the fluid in the cooling device. Furthermore, the location of the at least one condensing device in this area facilitates the easy supply of ambient air for cooling the at least one condensing device and for heat dissipation.Particularly while driving, the resulting airflow from the ambient air can be easily directed to the at least one condensing device to ventilate it and ensure effective cooling. This can be achieved, for example, through an air intake in the area of ​​the hood, the fenders, or a front air intake from which the ambient air can be directed to the at least one condensing device. The ambient air can also be directed to the at least one condensing device, for example, via the wheel wells. The at least one condensing device is installed in this area longitudinally along the vehicle as close as possible to the traction battery, so that even when the vehicle is tilted, a sufficient height difference between the evaporation device and the at least one condensing device is ensured.Due to the common upward slope of the vehicle towards the passenger compartment, i.e., towards the windshield, the at least one condensing device can be mounted at a particularly high point in front of the windshield. The at least one condensing device is preferably located directly below a front flap of the vehicle, classically referred to as the hood, in order to achieve the greatest possible height difference to the evaporating device. Thus, in typical vehicles, even with an inclination of, for example, 18°, a minimum height difference between the fluid level in the evaporating device within the housing and the at least one condensing device can still be achieved with such a mounting of the at least one condensing device, ensuring the cooling device functions as a thermosiphon.

[0050] In an advantageous embodiment, a connecting pipe designed as a riser, which conveys the fluid vaporized in the evaporation device to the at least one condensation device, is connected in an upper section to the housing body on a side facing away from the condensation device in the longitudinal direction of the vehicle, and in an upper section to the condensation device on a side facing the evaporation device in the longitudinal direction of the vehicle. This arrangement of the riser facilitates the transport of the gaseous fluid from the evaporation device to the at least one condensation device. The riser is preferably arranged such that, with respect to one lateral direction of the vehicle, it is located in an outer region of the vehicle, which simplifies the design and installation of the riser.

[0051] In an advantageous embodiment, a connecting line designed as a downpipe, which conveys condensed fluid from the at least one condensing device back to the evaporating device, is connected in a lower section to the housing body on a side facing the condensing device in the longitudinal direction of the vehicle and in a lower section to the condensing device on a side facing away from the evaporating device in the longitudinal direction of the vehicle. This arrangement of the downpipe facilitates the transport of the liquid fluid from the at least one condensing device to the evaporating device. The downpipe is preferably arranged such that, with respect to one lateral direction of the vehicle, it is located in an outer region of the vehicle, which simplifies its design and installation.

[0052] In an advantageous embodiment, the outlet of the at least one condensing device has at least a minimal height difference to the side of the housing body facing the condensing device when the vehicle is at its maximum inclination, for example 18° in the longitudinal direction. This ensures that the cooling device retains its function as a thermosiphon.

[0053] Further advantages, details, and features of the invention will become apparent from the exemplary embodiments described below. Specifically, the following will be shown: Figure 1: a schematic representation of an electrically powered vehicle with a traction battery and a cooling device according to a first, preferred embodiment of the present invention; Figure 2: a schematic representation of the vehicle's traction battery made of Fig. 1with battery cells arranged therein and a cooling device with several cooling elements in three views; Figure 3: a schematic representation of the vehicle's cooling device made of Fig. 1 with an inclination due to a slope and a resulting fluid distribution; Figure 4: a schematic representation of a cooling device according to a second embodiment of the present invention with two condensing devices, wherein one of the condensing devices is designed as a chiller and is coupled to an air conditioning system of the vehicle; and Figure 5: a schematic representation of a cooling device according to a third embodiment of the present invention with a first and a second cooling circuit.

[0054] In the following description, identical reference numerals denote identical components or identical features, so that a description of a component in relation to one figure also applies to the other figures, thus avoiding repetitive descriptions. Furthermore, individual features described in connection with one embodiment can also be used separately in other embodiments.

[0055] Figures 1 to 3 The provisions relate to an electrically powered vehicle 1 according to a first, preferred embodiment of the present invention. The electrically powered vehicle 1 can be a vehicle 1 with exclusively an electric drive, or a so-called hybrid vehicle with an electric drive in combination with a conventional drive, in particular an internal combustion engine.

[0056] The vehicle 1 includes a traction battery 2 for providing electrical energy for the electric drive of the vehicle 1. In this embodiment, the traction battery 2 is a high-performance battery that can be operated with voltages of up to several hundred volts or even up to 1000 volts and charging and discharging currents of several hundred amperes up to 1000 amperes.

[0057] The traction battery 2 comprises a housing 3 in which a plurality of battery cells 4 are accommodated. In this embodiment, the battery cells 4 are manufactured using lithium-ion technology and operate best in a temperature range of, for example, 15° to 40°C with high temperature homogeneity and a temperature variation of 2–4°C within and between the battery cells 4. The battery cells 4 of the first embodiment are arranged in the housing 3 in several battery modules 5, as shown in Figure 1is shown.

[0058] Vehicle 1 also includes a cooling device 6. The cooling device 6 is in Figure 3 Partially shown separately. The cooling device 6 comprises an evaporation device 7 mounted in the housing body 3. The evaporation device 7 is mounted in a floor area 8 of the vehicle 1. The traction battery 2, with its housing body 3 and the evaporation device 7 mounted therein, is arranged below a passenger compartment 9 of the vehicle 1, specifically between a front and a rear axle 10, 11 of the vehicle 1. The evaporation device 7 comprises a plurality of evaporation elements 23, each individually arranged between two battery cells 4, as shown in Figure 2As shown, the evaporation elements 23 are made of an electrically non-conductive material. The corresponding battery modules 5 thus comprise, in addition to the battery cells 4, the evaporation elements 23. The battery modules 5 are attached to the housing body 3 by means of screws 29.

[0059] The evaporation elements 23 have microchannel structures that are at least partially open laterally. Contact between the evaporation elements 23 and the adjacent battery cells 4 closes the microchannel structures laterally, thereby forming microchannels 24 within the evaporation elements 23. The microchannels 24 extend vertically 16 and are open at both ends.

[0060] The evaporation device 7 is integrated into the housing body 3 of the traction battery 2 as a separate component. Alternatively, the evaporation device 7 can be an integral part of the base body 3.

[0061] The cooling device 6 further comprises two condensing devices 12, 13, which are mounted outside the housing 3 of the traction battery 2. Specifically, the two condensing devices 12, 13 are mounted distributed along the vehicle 1. A front condensing device 12 is positioned longitudinally 14 of the vehicle 1 in front of the traction battery 3 with the evaporating device 7, while a rear condensing device 13 is positioned longitudinally 14 of the vehicle 1. 11 of the vehicle 1 is positioned behind the traction battery 3 with the evaporation device 7.

[0062] The front condensing device 12 is located in an area above the wheel arches of the front axle 10 of the vehicle 1 at the windshield-side end of the hood 15 of the vehicle 1. In this area, the front condensing device 12 is installed longitudinally 14 of the vehicle 1, close to the traction battery 3. The front condensing device 12 is positioned directly below the hood 15.

[0063] Additionally, the rear condensing device 13 is mounted in an area above the wheel arches of the rear axle 11 of the vehicle 1, with the rear condensing device 13 being mounted in this area longitudinally 14 of the vehicle 1 close to the traction battery 3. This results in a height difference h, which is exemplified for the rear condensing device 13 in Figure 1 is shown.

[0064] As in Figure 1As shown, the evaporation device 7 is arranged in a vertical direction 16 with the height difference h below the two condensation devices 12, 13.

[0065] Connecting lines 17 and 18 are arranged between the evaporation device 7 and the two condensation devices 12 and 13, forming a fluid connection. Specifically, the connecting lines 17 and 18 comprise a rising line 17 and a falling line 18, which are arranged between the evaporation device 7 and each of the two condensation devices 12 and 13. This results in a parallel connection between the two condensation devices 12 and 13 and the evaporation device 7.

[0066] The risers 17 are each connected in an upper section to the housing body 3 on a side facing away from the condensing device 12, 13 in the longitudinal direction 14 of the vehicle 1, and in an upper section to the corresponding condensing device 12, 13 on a side facing the evaporating device 7 or the housing body 3 in the longitudinal direction 14 of the vehicle 1. In this exemplary embodiment, the risers 17 are arranged such that they are located in an outer region of the vehicle 1 with respect to a lateral direction.

[0067] The downpipes 18 are connected in a lower section to the housing body 3 on a side facing the longitudinal direction 14 of the vehicle 1 towards the condensing device 12, 13, and in a lower section to the corresponding condensing device 12, 13 on a side facing away from the evaporating device 7 or the housing body 3 in the longitudinal direction 14 of the vehicle 1. In this exemplary embodiment, the downpipes 18 are arranged such that they are located in an outer region of the vehicle 1 with respect to a lateral direction.

[0068] A fluid 19 is included in the cooling device 6, as shown in the Figure 2 and 3The fluid 19 in this embodiment has a boiling point in a range between 10°C and 80°C at ambient pressure. Preferably, the fluid 19 has a boiling point below the maximum temperature of the traction battery 2. The fluid 19 is a dielectric fluid, which is electrically non-conductive. The fluid 19 is collected in liquid form in a plenum 30 within the housing 3 of the traction battery 2, as shown in Figure 2 is shown.

[0069] The two condensing devices 12, 13 each have a pressure equalization device 20 for pressure equalization between an interior 42 of the cooling device 6 and an external environment 34. As in Figure 1As shown, the two pressure equalization devices 20 are each designed in the form of a chimney, with a pressure equalization opening 21 at the upper end and a pressure equalization valve 22 below it. The pressure equalization device 20 is located in an A-pillar 31 of the vehicle 1 (i.e., at the front and rear ends of the passenger compartment 9, respectively) for the front condensing device 12 and in a C-pillar 32 for the rear condensing device 13.

[0070] Through the pressure equalization opening 21, a ventilation gas, which in this embodiment is ambient air, can be admitted (ventilation) and / or a venting gas can be released from the cooling device 6 (venting). The pressure equalization valve 22 opens when the pressure inside the cooling device 6 falls below a limit pressure, for example, below 0.8 bar. Incoming ventilation gas is then dried via the pressure equalization device 20, for example, by means of a replaceable drying cartridge, which is not shown separately. The cooling device 6 can be vented via the two pressure equalization devices 20.

[0071] During venting, a material separation of the gaseous fluid 19 and the ventilation gas taken in during a previous venting occurs in the two pressure equalization devices 20. This separation occurs, on the one hand, due to a density difference between the gaseous fluid 19 and the ventilation gas, i.e., the previously taken-in ambient air, along the length of the two pressure equalization devices 20.

[0072] Alternatively or additionally, a filter device, for example an activated carbon filter, can be arranged in the pressure equalization device 20, which retains gaseous fluid 19 during venting. The activated carbon filter is preferably discharged again during operation by actively supplying heat, thereby recovering the fluid 19 absorbed in it. Alternatively or additionally, the filter device can comprise a zeolite material, a filter membrane, or a chemical filter. The filter device is not shown separately in the figures.

[0073] Alternatively or additionally, the pressure equalization devices 20 can be actively cooled during venting, so that the gaseous fluid 19 contained in the gas rising in the pressure equalization devices 20 condenses, and only remaining gas, ideally exclusively previously absorbed venting gas, escapes. The condensed fluid 19 can then be returned in its liquid state from the pressure equalization device 20 to the respective condensing device 12, 13 based on its own gravity.

[0074] The following describes a first cooling circuit 33 generated in the cooling device 3 during operation for cooling the battery cells 4 of the traction battery 2. The first cooling circuit 33 in the cooling device 6 is in Figure 3 depicted.

[0075] During operation, i.e., when charging or discharging the traction battery 2, heat is generated. This heat is transferred from the battery cells 4 to the liquid fluid 19 by means of the evaporation device 7. In this embodiment, the evaporation device 7 is designed as an immersion evaporator. The microchannels 24 are in fluid contact with the plenum 30. This allows liquid fluid 19 to penetrate the microchannels 24, where it is heated by the heat generated by the battery cells 4. As the liquid fluid 19 absorbs heat from the battery cells 4 of the traction battery 2, it evaporates in the evaporation device 7. During this process, liquid fluid 19 is entrained, which wets the microchannels 24 internally. After wetting, heat transfer can occur along the entire length of the microchannels 24, resulting in highly efficient cooling.Alternatively, the battery cells 4 and the evaporation elements 23 can be partially immersed in the liquid fluid 19 in the housing 3 of the traction battery 2, so that the microchannels 24 are partially filled with liquid fluid 19. Liquid fluid 19 can also flow from the plenum 30 into the microchannels 24.

[0076] The evaporation device 7 is therefore a heat exchanger in which heat is transferred from the battery cells 4 to the liquid fluid 19, causing it to evaporate. Accordingly, such an evaporation device 7 is also known as an evaporator. Due to its low density, the gaseous fluid 19 rises in the riser lines 17 to the two condensation devices 12, 13.

[0077] The two condensing devices 12, 13 are also heat exchangers that absorb heat from the gaseous fluid 19 and transfer it to the surroundings, causing the gaseous fluid 19 to condense. Such a condensing device 12, 13 is also known as a steam condenser or liquefier.

[0078] The condensed fluid 19 can flow back through the downpipe 18 from the respective condensing device 12, 13 to the evaporating device 7. The transport of the liquid fluid 19 occurs solely due to gravity, which causes the liquid fluid 19 to flow back into the housing body 3, where it is again made available to the evaporating device 7.

[0079] In this embodiment, the first cooling circuit 33 is designed as a natural circulation circuit without active circulation of the fluid 19. Accordingly, in the cooling device 6, the evaporated fluid 19 is passively transported from the evaporation device 7 to the condensation devices 12, 13, and the condensed fluid 19 is passively transported from the condensation devices 12, 13 to the evaporation device 7, as described above. The cooling device 6 is thus designed as a thermosiphon. The thermosiphon is therefore a passive structure that enables heat exchange by utilizing natural convection in a vertical fluid circuit between the evaporation device 7 and the condensation devices 12, 13.The thermosiphon function is based on the density difference between the liquid and gaseous phases of the fluid 19. Due to its lower density, the gaseous fluid 19 flows or rises in the riser pipes 17 to the condensing devices 12, 13, and the condensed fluid 19 flows back or sinks from the condensing devices 12, 13 through the downpipe 18 into the evaporating device 7 under the influence of gravity. The liquid fluid 19 can then flow back or sink into the housing 3 of the traction battery 2, where the plenum 30 of liquid fluid 19 is formed, from where it enters the evaporating device 7.

[0080] In the thermosiphon, with the steam-filled risers 17 and liquid-filled droprs 18 arranged vertically, different pressures prevail at the bottom of the pipes 17, 18, which are connected to the evaporation device 7, due to the different densities of the respective steam and liquid columns. As the fluid 19 evaporates and is further heated in the evaporation device 7, the concentration of the gaseous fluid 19 increases. Pressure equalization between the risers 17 and the droprs 18 is achieved by liquid fluid 19 flowing from the droprs 18 into the evaporation device 7 and thus towards the steam column in the risers 17, displacing gaseous fluid 19 into the risers 17. The gaseous fluid 19 flows from the risers 17 into the condensation devices 12, 13, where it condenses again, thus closing the first cooling circuit 33.

[0081] A continuous thermosiphon-like cycle of the liquid fluid 19 is formed in the cooling device 6 by the continuous evaporation of the liquid fluid 19 at the bottom of the risers 17, i.e., in the evaporation device 7, and the condensation of the gaseous fluid 19 at the top of the risers 17, i.e., in the condensing devices 12, 13, as well as the subsequent return of the condensed fluid 19 from the condensing devices 12, 13 to the downpipes 18. This creates a continuous cycle of the fluid 19 in the cooling device 6. A dynamic circulation is generated in the cooling device 6. Active circulation of the fluid 19 by a pump or compressor is not required.

[0082] As described above, the cooling device 6 provides two-phase cooling. In the evaporation device 7, the liquid fluid 19 absorbs heat from the battery cells 4, causing it to evaporate. In the two condensation devices 12 and 13, it releases heat to the environment 34 of the vehicle 1, causing the gaseous fluid 19 to condense again. During circulation in the first cooling circuit 33, the liquid fluid 19 absorbs heat of vaporization as it evaporates. This heat is then released as it condenses from its gaseous state in the two condensation devices 12 and 13. The heat of vaporization can thus be dissipated from the battery cells 4 of the traction battery 2 and released to the external environment 34.

[0083] The cooling device 6 thus formed ensures reliable operation, which is not impaired even when the vehicle 1 is at a greater inclination, as can be seen from the Figure 1 and 3This results in the following: Thus, in typical vehicles 1 with the cooling device 6 of the first embodiment, even at an inclination of, for example, 18°, a height difference h' between a liquid level 25 of the fluid 19 in the evaporation device 7 in the housing body 3 and the condensation devices 12, 13, in particular an outlet 26 of the condensation devices 12, 13 for condensed fluid 19, can still be maintained, as shown in the Figure 1 and 3 The figure shows a normal position 27 of the vehicle 1 with additional inclined positions 28 of +18° and -18° respectively relative to the normal position 27. As shown in Figure 3As shown, the outlet 26 of the front condensing device 12 for condensed fluid 19 is located at the specified vehicle inclination with a height difference h' above the liquid level 25 of the liquid fluid 19 in the housing body 3 of the traction battery 2, whereby the condensed fluid 19 can flow into the housing body 3 by gravity.

[0084] Figure 4 Figure 1 shows a cooling device 6 of an electrically powered vehicle 1 according to a second embodiment of the present invention. The cooling device 6 of the second embodiment largely corresponds to the cooling device 6 of the first embodiment, so that only differences between the two cooling devices 6 are discussed below.

[0085] The cooling device 6 of the second embodiment differs from the cooling device 6 of the first embodiment in that one of the two condensing devices 12, 13, here by way of example the front condensing device 12, is designed as a chiller for coupling with an air conditioning system 35 of the vehicle 1. The chiller serves as a controllable heat sink depending on whether the air conditioning system 35 of the vehicle is operating. 1. The air conditioning system 35 comprises an air conditioning circuit 36 ​​with a separate refrigerant. The air conditioning circuit 36 ​​contains a throttle valve 37, a receiver 38, an air conditioning condenser 39 for dissipating heat to the environment 34, and an air conditioning compressor 40.

[0086] In the Figure 4In the embodiment shown, the two condensing devices 12, 13 are connected downstream of each other. Alternatively, the two condensing devices 12, 13 can be connected in parallel with the evaporating device 7, as described above with reference to the first embodiment.

[0087] In another, alternative embodiment, both condensing devices 12, 13 are designed as chillers for coupling with the air conditioning system 35 of the vehicle 1.

[0088] The cooling device 6 additionally includes a control unit 41, which is designed to detect an impending load on the traction battery 2, particularly during fast charging, and which is further designed to pre-cool the traction battery 2 and / or the fluid 19 with the cooling device 6 when an impending load is detected. This control can be effected, for example, by controlling the air conditioning system 35 of the vehicle 1. Additionally, the control unit 41 can appropriately control the ventilation valves 22 to actively equalize the pressure between an interior 42 of the cooling device 6 and the environment 34. Alternatively or additionally, the control unit 41 can supply an increased quantity of ambient air to the other condensing device 12, 13 from the outside via a fan (not shown).

[0089] Figure 5Figure 1 shows a cooling device 6 of an electrically powered vehicle 1 according to a third embodiment of the present invention. The cooling device 6 of the third embodiment is largely identical to the cooling device 6 of the first embodiment, so that only differences between the two cooling devices 6 are discussed below.

[0090] The cooling device 6 of the third embodiment differs from the cooling device 6 of the first embodiment in that the cooling device 6 has a further condensing device 43 and further connecting hoses 44 for forming a second cooling circuit 45, as shown in Figure 5 The two cooling circuits 33, 45 are connected to each other via a collector 46 for collecting liquid fluid 19, i.e. the collector 46 is arranged at a connection between the first cooling circuit 33 and the second cooling circuit 45.

[0091] The second cooling circuit 45 includes a compressor as a circulation device 47 for conveying the fluid 19 and increasing the pressure. Furthermore, the second cooling circuit 45 includes an adjusting throttle 48 for setting a pressure level. Finally, the second cooling circuit 45 also comprises a collection tank 49.

[0092] In Figure 5 The two condensing devices 12, 13 are shown together. The two condensing devices 12, 13 are preferably connected in parallel to the evaporation device 7. Figure 5 The two condensing devices 12, 13 and the collector 46 are connected downstream of each other. Alternatively, the two condensing devices 12, 13 and the collector 46 can be connected in parallel with the evaporating device 7, as described above with regard to the arrangement of the two condensing devices 12, 13 of the first embodiment. Reference symbol list

[0093] 1 Vehicle 2 Traction battery 3 Housing 4 Battery cell 5 Battery module 6 Cooling device 7 Evaporator 8 Floor area 9 Passenger compartment 10 Front axle 11 Rear axle 12 Front condenser 13 Rear condenser 14 Longitudinal direction 15 Hood 16 Vertical direction 17 Riser, connecting line 18 Drop, connecting line 19 Fluid 20 Venting device 21 Vent opening 22 Vent valve 23 Evaporator element 24 Microchannel 25 Fluid level 26 Outlet 27 Normal position 28 Inclined position 29 Screw medium 30 Plenum 31 A-pillar 32 C-pillar 33 First cooling circuit 34 Ambient 35 Air conditioning 36 Air conditioning circuit 37 Throttle valve 38 Collector 39 Air conditioning condenser 40 Air conditioning compressor 41 Control unit 42 Interior 43 Additional condensing device 44 Additional connecting hoses 45 Second cooling circuit 46 Collector 47 Compressor circulation device 48 Adjusting throttle 49 Collection tank hHeight difference without vehicle tilt h'Height difference with vehicle tilt

Claims

1. Cooling device (6) for cooling a traction battery (2) of a vehicle (1) by means of a fluid (19), comprising an evaporation device (7) for installing in a housing body (3) of the traction battery (2), at least one condensation device (12, 13) for installing on the vehicle (1) outside of the housing body (3) of the traction battery (2), and connection lines (17, 18) which conduct fluid (19) evaporated in the evaporation device (7) to the at least one condensation device (12, 13) and condensed fluid (19) from the at least one condensation device (12, 13) back to the evaporation device (7), wherein the evaporation device (7), the at least one condensation device (12, 13) and the connection lines (17, 18) form a first cooling circuit (33), and the first cooling circuit (33) is designed in the form of a natural circulation, wherein a circulation of the fluid (19) through the first cooling circuit (33) includes transporting gaseous fluid (19) from the evaporation device (7) to the at least one condensation device (12 ,13) and transporting liquid fluid (19) from the at least one condensation device (12, 13) back to the evaporation device (7), and the circulation is carried out in operation on the basis of differences in density between the fluid (19) evaporated in the evaporation device (7) and the fluid (19) condensed in the at least one condensation device (12, 13), and on the basis of a difference in height between the at least one condensation device (12, 13) and the evaporation device (7), characterized in that the evaporation device (7) is designed as an immersion evaporator and comprises at least one evaporation element (23), microchannels (24) are formed in the at least one evaporation element (23), or the at least one evaporation element (23) comprises microchannel structures for forming microchannels (24) together with battery cells (4) of the traction battery (2), or microchannel structures are formed between a plurality of evaporation elements (23) to form microchannels (24) between the evaporation elements (23) and together with battery cells (4) of the traction battery (2), and the evaporation elements (23) are arranged in such a way that liquid fluid (19) evaporates in the microchannels while absorbing heat from the battery cells (4).

2. Cooling device (6) according to claim 1, characterized in that the evaporation device (7) is arranged in a vertical direction (16) below the at least one condensation device (12, 13).

3. Cooling device (6) according to claim 1 or 2, characterized in that the first cooling circuit (33) comprises a plurality of condensation devices (12, 13), and the plurality of condensation devices (12, 13) is designed for a distributed installation on the vehicle (1), in particular in the longitudinal direction (14) of the vehicle (1) in front of and behind the evaporation device (7).

4. Cooling device (6) according to any of the preceding claims, characterized in that at least one condensation device (12, 13) is designed as a chiller for coupling to an air conditioning system (35) of the vehicle (1) in order to dissipate heat from the first cooling circuit (33) via the air conditioning system (35).

5. Cooling device (6) according to any of the preceding claims, characterized in that the cooling device (6) comprises a further condensation device (43) and further connection hoses (44) to form a second cooling circuit (45), and the second cooling circuit (45) comprises a circulation device (47) for conveying the fluid (19) in the second cooling circuit (45).

6. Cooling device (6) according to claim 5, characterized in that the second cooling circuit (45) comprises at least one valve device for fluidic separation from or connection to the first cooling circuit (33).

7. Cooling device (6) according to any of the preceding claims, characterized in that the cooling device (6) has a collector (46) for collecting the liquid fluid (19), wherein the collector (46) is arranged in particular at a connection between the first cooling circuit (33) and the second cooling circuit (45).

8. Cooling device (6) according to any of the preceding claims, characterized in that the cooling device (6) comprises a control device (41) which is designed to detect an impending load on the traction battery (2), in particular during rapid charging, and which is also designed to pre-cool the traction battery (2) and / or the fluid (19) with the cooling device (6) when an imminent load is detected; and / or characterized in that the cooling device (6), in particular at least one condensation device (12, 13), comprises a pressure compensation device (20) for pressure compensation between an interior (42) of the cooling device (6) and an external environment (34).

9. Electrically drivable vehicle (1) comprising a traction battery (2) and a cooling device (6) according to any of the preceding claims 1 to 8, wherein the traction battery (2) with its housing body (3) and the evaporation device (7) installed therein is installed in a floor region (8) of the vehicle (1), the at least one condensation device (12, 13) is installed outside of the traction battery (2) in a region above the evaporation device (7), and a fluid (19) is accommodated in the cooling device (6).

10. Vehicle (1) according to claim 9, characterized in that the traction battery (2) with its housing body (3) and the evaporation device (7) installed therein is arranged underneath a passenger compartment (9) of the vehicle (1), preferably between a front and a rear axle (10, 11) of the vehicle (1).

11. Vehicle (1) according to either claim 9 or claim 10, characterized in that the at least one condensation device (12, 13) is installed in a region above a rear axle (11) of the vehicle (1), in particular above wheel housings of the rear axle (11).

12. Vehicle (1) according to any of the preceding claims 9 to 11, characterized in that the at least one condensation device (12, 13) is installed in a region above a front axle (10) of the vehicle (1), in particular above wheel housings of the front axle (10), preferably at an end of a hood (15) of the vehicle (1) on the windshield side.

13. Vehicle (1) according to any of the preceding claims 9 to 12, characterized in that a connection line (17, 18) designed as a riser (17), which conducts fluid (19) evaporated in the evaporation device (7) to the at least one condensation device (12, 13), is connected to the housing body (3) in an upper region on a side facing away from the condensation device (12, 13) in the longitudinal direction (14) of the vehicle (1), and is connected to the condensation device (12, 13) in an upper region on a side facing the evaporation device (7) in the longitudinal direction (14) of the vehicle (1).

14. Vehicle (1) according to any of the preceding claims 9 to 13, characterized in that a connection line (17, 18) designed as a downcomer (18), which returns condensed fluid (19) from the at least one condensation device (12, 13) to the evaporation device (7), is connected to the housing body (3) in a lower region on a side facing the condensation device (12, 13) in the longitudinal direction (14) of the vehicle (1), and is connected to the condensation device (12, 13) in a lower region on a side facing away from the evaporation device (7) in the longitudinal direction (14) of the vehicle (1).

15. Vehicle (1) according to the preceding claim 16, characterized in that the outlet of the at least one condensation device (12, 13) has at least a minimum difference in height (h') to a side of the housing body (3) facing the condensation device (12, 13) at a maximum vehicle inclination, for example 18° in the longitudinal direction (14).