Device and method for cooling an HV battery, vehicle having an HV battery

Abstract

The invention relates to a device for cooling an HV battery (2) by means of a cooling fluid which flows through a heat exchanger arrangement (3). The device according to the invention is characterised in that the heat exchanger arrangement (3) comprises at least one first heat exchanger designed as a base cooler (4) and at least one second heat exchanger designed as an intermediate cell cooler (12), and at least one valve apparatus (11) for the requirements-based dividing of the cooling fluid between the heat exchangers.

Description

[0001] Device and method for cooling an HV battery, vehicle with an HV battery

[0002] The invention relates to a device for cooling an HV battery having the features defined in more detail in the preamble of claim 1. Furthermore, the invention relates to a method for cooling an HV battery using such a device, as well as to a vehicle having an HV battery cooled by such a device.

[0003] So-called HV or high-voltage batteries are well-known in the art. The definition of a high-voltage battery in the automotive sector dates back to ECE R100. Such HV batteries are often used as traction batteries in at least partially electrically powered vehicles, such as hybrid vehicles, fuel cell vehicles, or especially battery-electric vehicles. Typically, such batteries, which are now often implemented using lithium-ion technology, require a means of temperature control for the individual battery cells that make up the HV battery. Temperature control involves heating in the event of very low ambient temperatures and the HV battery has reached these temperatures.However, for most of the operation, waste heat is produced by the HV battery, which must be dissipated as efficiently as possible in order to keep the battery in a temperature range suitable for operation.

[0004] So-called floor coolers or floor heat exchangers have become the most popular devices for cooling HV batteries. For example, DE 102010 032 899 A1 describes such a heat exchanger, referred to here as a cooling floor, which features a design optimized for cooling fluid flow. DE 102013200239 A1 also describes a cooling plate for cooling individual battery cells mounted on it. This document also describes a fan, which can be used additionally for cooling.

[0005] The first-mentioned document, in particular, describes an optimized floor cooling design using complex technology to dissipate as much heat as possible. However, in many operating situations, this isn't even necessary, so the additional design effort could easily be avoided.

[0006] In the second document mentioned, the cooler can also be operated if increased cooling requirements are required. However, since the individual battery cells of the HV battery are typically installed very densely, the additional cooling effect achieved in this way is very limited.

[0007] The object of the present invention is therefore to provide an optimized cooling system for an HV battery, which ensures efficient, demand-based cooling even with high dynamics with regard to the power drawn or fed in.

[0008] According to the invention, this object is achieved by a device having the features in claim 1, and in particular in the characterizing part of claim 1. Advantageous embodiments and further developments emerge from the dependent claims. A method having the features in claim 7, together with such a device, also achieves the object. Here, too, advantageous embodiments and further developments emerge from the dependent claims. The ideal application of such a device and such a method can be in a vehicle in which the HV battery is used as a traction battery.

[0009] The device according to the invention for cooling, or in principle also for temperature control more generally, an HV battery using a cooling fluid provides for this cooling fluid to flow through a heat exchanger assembly. Unlike the structures known from the prior art, the heat exchanger assembly comprises a first heat exchanger designed as a base cooler and a second heat exchanger designed as an inter-cell cooler. The heat exchanger assembly further comprises a valve device for distributing the cooling fluid between the two heat exchangers as required.

[0010] The design therefore relies on a conventional floor heat exchanger, as is also known from the prior art mentioned at the beginning. A second heat exchanger is also provided as an inter-cell cooler. The flow can be adjusted as required using at least one valve device. During normal operation, for example the regular operation of a vehicle in a normal or efficient operating mode, it is then sufficient to flow the cooling fluid through one of the heat exchangers, e.g. the floor cooler. This enables cooling to be achieved as in a conventional design known from the prior art. If more power is now required, for example because a vehicle with a correspondingly high drive power draws on this high power or because charging is carried out with a correspondingly high power, e.g. rapid charging of the HV battery, correspondingly more waste heat is generated in the area of ​​the individual battery cells.The conventional floor cooler is then very quickly exhausted in terms of the cooling capacity it can provide.

[0011] In the case of the current state-of-the-art systems, the power would now have to be regulated accordingly, so that, for example, in a vehicle application, the person driving the vehicle would no longer have the full desired power available or rapid charging of the HV battery would have to be slowed down accordingly, which would result in longer waiting times.

[0012] The device according to the invention can avoid these disadvantages by opening the valve device accordingly, thereby allowing cooling fluid to flow not only through one heat exchanger, e.g., the base cooler, but also through the other heat exchanger, in this case, the inter-cell cooler. The cooling capacity can be increased accordingly, ensuring sufficient cooling even in high-performance applications. This prevents unwanted power reduction.

[0013] According to a very advantageous development, the heat exchange arrangement can be provided with a common supply connection for the cooling fluid. Such a design makes it possible, for example, for different power categories of applications, such as vehicles with different available drive powers, to always provide the same design: one with a conventional HV battery and one with an HV battery that has the cooling device according to the invention. With regard to the connections, the design then remains unchanged, which benefits a modular construction concept.

[0014] According to a very advantageous embodiment, the valve device can be integrated into the device in such a way that it enables or blocks the volume flow of the cooling fluid to the inter-cell cooler. With this design, the flow through the base cooler is thus simple and efficient, as with conventional designs. Only when higher cooling capacity is required does the valve device also enable the inter-cell cooler, allowing the cooling fluid to flow through it as well.

[0015] A very advantageous further development of the structure according to the invention provides that the individual battery cells of the high-voltage battery are designed as round cells standing on the base cooler, wherein the intermediate cell cooler comprises a plurality of wave-shaped cooling lines which lie against the cylindrical outer surfaces of the individual battery cells.

[0016] Such a design with round cells is ideal for arranging a wave-shaped inter-cell cooler between the individual rows of round cells. For example, if the HV battery is divided into two modules, the respective wave-shaped cooling lines can branch off from a central arrangement of the supply and return lines of the inter-cell cooler and be arranged between the individual rows of battery cells. This makes the design extremely simple, efficient, and compact, especially when the wave-shaped cooling lines have both a supply and a return line, meaning they can simply end freely on the side facing away from the supply and return lines without the need for corresponding connections.

[0017] A method according to the invention for demand-based cooling of an HV battery using a device according to the invention provides that the valve device is controlled depending on the power flowing from or into the HV battery. The electrical power generated when charging or discharging the HV battery is a readily available quantity that is already available in the HV battery's electrical battery management system. Without the need for additional sensors or the like, the valve device can thus be controlled extremely simply and efficiently.

[0018] The method according to the invention can provide that during normal operation and during efficient operation of the HV battery, for example during normal operation or efficient operation in an electrically powered vehicle, only the base cooler is flowed through by the cooling fluid. A further very advantageous embodiment can then additionally provide that during charging and / or power operation, cooling fluid is passed through both heat exchangers. This results in particularly intensive cooling, for example during power operation of a high-performance vehicle or during rapid charging of the traction battery at a rapid charging station for vehicles with correspondingly high power outputs. If this high cooling capacity is no longer required, the cooling can be reduced to one of the heat exchangers in order to manage with less volume flow and thus also less drive power for the cooling.

[0019] As already indicated, the HV battery, together with the device and method according to the invention, can preferably be used as a traction battery in a vehicle, in particular a battery-electric vehicle. However, other applications are also conceivable in principle, for example, in the stationary sector or in other mobile systems.

[0020] Further advantageous embodiments of the device, the method and their use also emerge from the exemplary embodiment, which is described in more detail below with reference to the figures.

[0021] Showing:

[0022] Fig. 1 shows a schematically indicated battery-electric vehicle;

[0023] Fig. 2 shows a section of the vehicle’s traction battery in a side view; and

[0024] Fig. 3 is a plan view of the section according to Fig. 2. In the illustration in Figure 1, a vehicle designated 1 is shown purely schematically. This vehicle 1 is intended to be designed as a battery-electric vehicle. The electrical drive power is supplied via an HV battery 2, which is designed as a traction battery for the vehicle 1. This traction battery 2 is charged as needed and absorbs the power generated during recuperation. The vehicle 1 is intended to be a relatively powerful vehicle 1, which requires a relatively high electrical power for the powerful drive in high-performance operation. The high-voltage battery 2 can be dimensioned accordingly large for this purpose. In particular, however, a large amount of waste heat is generated when there is a high power requirement or when the battery is quickly charged at a high power level, for example.

[0025] In order to dissipate any waste heat generated, the high-voltage battery 2 has a heat exchange arrangement 3, the components of which are indicated in the illustration in Figure 2. A first crucial component of this heat exchange arrangement 3 is a first heat exchanger 4, which is designed as a base cooler 4 in a manner known per se. This base cooler 4 consists of a plate through which a cooling fluid, in particular a liquid cooling medium, actively flows, and on which individual battery cells designated 5 are arranged, only a few of which bear a reference numeral in Figures 2 and 3. The individual battery cells 5, designed here purely as examples as roundels with a cylindrical housing, stand on this base cooler 4, which is designed as a flat plate at least towards the top. This cools the individual battery cells 5, and in particular the bottom of their cell housing.As can be seen from the illustration in Figure 3, a supply line designated 6 and a return line designated 7 are provided as a common connection for the heat exchange arrangement 3 in the area of ​​the floor cooler 4. This is supplied with cool cooling fluid via the supply line 6; the heated cooling fluid flows out through the return line 7 and reaches, for example, the area of ​​a radiator (not shown here) of the vehicle 1, in which the cooling fluid is in turn cooled.

[0026] Figure 3 shows a plan view of the corresponding section analogous to the illustration in Figure 2, wherein the supply line 6 and the return line 7 into the cooling plate designated 4 are marked with corresponding arrows. In addition to the base cooler 4 as the first heat exchanger 4, an inter-cell cooler 12 is now provided. This comprises several undulating cooling lines 8, which are arranged between two adjacent rows of individual battery cells 5. These cooling lines 8 of the inter-cell cooler 12 can be seen as undulating cooling lines 8 with a thick solid line in the plan view according to Figure 3. The side view according to Figure 2 then shows the structure analogous to the illustration in Figure 3 without the row of individual battery cells 5 shown at the bottom in Figure 3. The undulating cooling lines 8 can consist of a undulating sheet metal with one or more cooling tubes (not shown here) for the supply and return lines.

[0027] A supply line 9 and a return line 10 run between two blocks of individual battery cells 5. The supply line 9 and the return line 9 are each connected to the cooling lines 8 of the intercooler 12, so that cooling fluid flows through each existing cooling line 8 parallel to the other cooling lines 8. This cools the cylindrical cell shells of the individual battery cells 5.

[0028] In practice, cooling via the floor cooler 4 is completely sufficient for many cooling tasks, such as efficient ferry operation of the vehicle 1 or normal operation of the vehicle 1 as well as charging the high-voltage battery 2 over a longer period of time, for example recharging at a private wall box overnight. In this operation, the floor cooler 4 is supplied with the cooling fluid via the flow line 6 and, if necessary, enables appropriate cooling of the high-voltage battery 2 or its individual battery cells 5. In the event of a high power requirement, for example when the vehicle 1 is traveling at high or highest available power or when quickly charging the high-voltage battery 2, it can happen that much more waste heat is generated than can be efficiently dissipated by the floor cooler 4.In the worst case, and this is quite common for state-of-the-art vehicles, this would lead to a reduction in power, so that either the desired driving performance of vehicle 1 is not fully available or rapid charging can only take place with reduced power and thus a correspondingly longer charging time.

[0029] To prevent this and ensure the full performance of the HV battery 2 in all situations, the inter-cell cooler 12 is provided. Via a valve device designated 11 as part of the heat exchange arrangement 3, a volume flow of the cooling fluid can now be directed not only through the base cooler 4 but also through the inter-cell cooler 12 or its cooling lines 8. This is indicated by the indicated valve device 11 and the corresponding arrows between the valve device 11 and the flow line 9 in the illustration in Figure 3. If the valve device 11 is opened, the inter-cell coolers 12 also flow through the base cooler 4, increasing the cooling performance. Although this requires higher peripheral power to maintain the cooling circuit, the resulting waste heat can be completely dissipated, so that no power reduction is necessary.If a normal journey or an energy-efficient journey subsequently takes place, cooling can again be carried out exclusively via the floor cooler 4 by closing the valve device 11, so that cooling with higher energy efficiency is realized for such standard cases.

[0030] The valve device 11 can therefore be controlled or regulated in particular based on the power charged into or taken from the HV battery 2.

[0031] In addition to the described case in which the floor cooler 4 functions as the standard cooler and the intercell cooler 12 as the additional cooler, the structure can of course also be implemented in such a way that this is reversed, i.e. the intercell cooler 12 takes over the standard cooling and the floor cooler 4 is switched on when required.

Claims

Patent claims 1. Device for cooling an HV battery (2) by means of a cooling fluid which flows through a heat exchange arrangement (3), characterized in that the heat exchange arrangement (3) comprises at least one first heat exchanger designed as a base cooler (4) and at least one second heat exchanger designed as an intercell cooler (12), as well as at least one valve device (11) for dividing the cooling fluid between the heat exchangers as required.

2. Device according to claim 1, characterized in that the heat exchange arrangement (3) has a common supply connection (6, 7) for the cooling fluid.

3. Device according to claim 1 or 2, characterized in that the valve device (11) releases or blocks the volume flow of the cooling fluid to the at least one inter-cell cooler (12).

4. Device according to claim 1, 2 or 3, characterized in that Individual battery cells (5) of the HV battery (2) are designed as round cells standing on the base cooler (4), wherein the intermediate cell cooler (12) comprises a plurality of wave-shaped cooling lines which rest on the lateral surfaces of the individual battery cells (5).

5. Device according to claim 4, characterized in that each of the wave-shaped cooling lines (8) comprises a flow and a return, which are connected to parallel flow lines (9) and return lines (10) of the inter-cell cooler (12).

6. Device according to claim 5, characterized in that the flow line (9) and the return line (10) are arranged on the same side of the individual battery cells (5) cooled by the respective wave-shaped cooling element.

7. Method for the demand-based cooling of an HV battery (2) by means of a device according to one of claims 1 to 6, characterized in that the valve device (11) is controlled as a function of the power flowing from or into the HV battery (2).

8. The method according to claim 7, characterized in that in normal operation and in an efficient operation of the HV battery (2) only one of the heat exchangers (4) is flowed through by the cooling fluid.

9. Method according to claim 7 or 8, characterized in that in charging and / or power operation, in particular in rapid charging operation, cooling fluid is passed through both heat exchangers (4, 8).

10. Vehicle (1) with an HV battery (2) as traction battery and a device according to one of claims 1 to 6 for cooling the same.

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