Thermal management system for a motor vehicle battery and method for thermal management of a motor vehicle battery

Abstract

Thermal management system (10) for a battery (20) of a motor vehicle, wherein the thermal management system (10) comprises a first air circuit (11) for heating or cooling an interior (14) of the vehicle, wherein the first air circuit (11) includes a first heat pump (12), wherein the first heat pump (12) is elastocaloric and comprises an elastocaloric material, characterized by the fact that the first heat pump (12) is designed to heat or cool air, and the thermal management system (10) comprises a first air duct (13) from the first heat pump (12) to the battery (20) of the motor vehicle and / or to a coolant circuit (21) of the battery (20) in order to use air heated or cooled by means of the first heat pump (12) for heating or cooling the battery (20).

Description

[0001] The present invention relates to a thermal management system for a battery of a motor vehicle, a method for thermal management of a battery and a motor vehicle according to the independent claims.

[0002] Elastocaloric heat pumps are generally known, for example from DE 10 2020 102 613 A1. However, the heat energy obtained from the elastocaloric heat pump is not used for heat transfer to the vehicle's battery. Furthermore, there is no feedback of heat energy to the elastocaloric heat pump.

[0003] German patent application DE 10 2020 002 845 A1 discloses a ventilation system for the interior of a motor vehicle. The ventilation system comprises a duct assembly and a temperature control module. The duct assembly includes a main air duct (HL duct) with a main air inlet, a main air outlet, and a main air drain leading to the outside. The duct assembly also includes a coolant duct (KL duct) with a coolant inlet, a coolant outlet, and a coolant drain leading to the outside. The main air duct and the coolant duct are connected to each other by means of a bypass duct assembly, which is located downstream of the main air inlet and the coolant inlet and upstream of the temperature control module. The temperature control module comprises a thermal heating module and a thermal cooling module, which interact thermally. The heating module is associated with the main air duct and the cooling module with the coolant duct.

[0004] Based on this, the present invention aims to use the thermal energy of the elastocaloric heat pump not only for cooling or heating the interior of the vehicle, but also for cooling or heating the vehicle's battery.

[0005] The aforementioned task is solved by a thermal management system for a motor vehicle battery. This applies in particular to electric vehicles, battery-electric vehicles, or hybrid vehicles.

[0006] The thermal management system features a primary air circuit for heating or cooling the vehicle's interior. This primary air circuit includes a primary heat pump, which is elastocaloric and therefore incorporates an elastocaloric material.

[0007] The first heat pump primarily comprises elastocaloric elements, which are advantageously formed at least partially from a thermoelastic material and / or a shape memory alloy element. For example, the thermoelastic elements can be in the form of wires. In particular, the heat pump can include a wire bundle comprising spaced-apart, parallel wires. The elastocaloric elements can also be formed entirely from a thermoelastic material and / or a shape memory alloy element.

[0008] The term "elastocaloric" refers to the fact that a temperature change is caused by the deformation of the elastocaloric elements. To achieve this deformation, the first heat pump incorporates an electrically driven actuator or motor that stretches the element. This process utilizes a phase change in the internal crystal structure of the elastocaloric elements. When the elastocaloric element, particularly a suitable shape-memory alloy, is stretched, a phase change in the internal crystal structure occurs. For example, the austenite structure can transition into a martensite structure. During this phase change, the material heats up, and the generated heat is then released into the surrounding air and thus used to generate heat. After stretching, the elastocaloric element returns to its original size, absorbing heat from the surrounding air in the process.This effect can thus be used to cool the surrounding air. The first heat pump has both an inlet and an outlet for outside air and for the indoor air. The first heat pump can heat or cool air from the indoor air. Furthermore, it can also supply fresh air. In other words, at least some of the heated or cooled fresh air is supplied to the indoor air. The thermal management system can also include exactly two fans: one for drawing in outside air and a second for exhausting indoor air.

[0009] The first heat pump comprises, in particular, a first section in which air is heated and a second section in which air is cooled, the first heat pump further comprising valves so that the supplied outside air and / or the supplied cabin air can be fed to the first section and / or the second section. If, for example, the interior is to be heated, both air from the interior and outside air (as fresh air) can be supplied to the first section of the heat pump.

[0010] Both regions have an inlet and an outlet. This allows heat to be transferred to or absorbed from the passing air within these regions. The elastocaloric elements are preferably movable relative to the first and second regions. The first and second regions can be subregions of an annular volume in which at least some of the elastocaloric elements are arranged. The elastocaloric elements can move clockwise or counterclockwise, passing through the regions alternately. For example, an element can first pass completely through the first region, then enter the second region, which it then traverses before returning to the first region.The elastocaloric elements are controlled in such a way that they expand upon entering the first zone, releasing heat to the air in that zone. Upon entering the second zone, they return to their original size, extracting heat from the air in that zone. In this way, the air in the first zone is heated and the air in the second zone is cooled. Depending on whether outside air, interior air, or a mixture of both is supplied to the first or second zone, the interior can be heated (heating mode) or cooled (cooling mode). In other words, the first heat pump is designed to deliver heated or cooled air to the interior, specifically the vehicle's cabin.

[0011] The first heat pump is designed to heat or cool air, especially the air for the interior, with the thermal management system comprising a first air duct from the first heat pump to the vehicle battery and / or to a coolant circuit of the vehicle battery, in order to use air heated or cooled by the first heat pump for heating or cooling the battery.

[0012] In particular, the first air duct is designed such that it directs air heated or cooled by the first heat pump directly to the battery for direct heat transfer. The heat transfer thus takes place directly between the air and a material within the battery. This is therefore a direct air heat transfer between the battery and the air that has been heated or cooled by the first heat pump.

[0013] Furthermore, the coolant circuit for heating or cooling the battery can comprise a coolant and an air-to-coolant heat exchanger, in particular a radiator. The first air duct can be designed to guide the air heated or cooled by the first heat pump into the air-to-coolant heat exchanger. This provides an indirect benefit to the air heated or cooled by the first heat pump, as it is first transferred to a coolant via the air-to-coolant heat exchanger and then passed on to the battery via the coolant.

[0014] The air-to-coolant heat exchanger is also designed to alternatively draw in outside air and transfer heat energy from the coolant to the outside air, or vice versa. The air-to-coolant heat exchanger can therefore be supplied with either outside air or air from the first heat pump, depending on requirements.

[0015] This allows for a very simple and efficient battery cooling system without the need for large additional components. A key advantage over direct air cooling of the battery from the first heat pump is that the large heat transfer surfaces are located outside the battery, and good airflow across these surfaces is easily achieved using the air-to-coolant heat exchanger. This allows for a high volume flow rate with low power consumption from the air-to-coolant heat exchanger. Furthermore, the cooling is particularly homogeneous compared to direct air cooling.

[0016] The coolant circuit can further include, in particular, the battery and a pump for pumping the coolant to the battery and / or from the battery back to the air-to-coolant heat exchanger. Specifically, the coolant circuit does not have a separate chiller, i.e., a separate unit for pre-cooling the coolant, as this is already performed by the first heat pump. In detail, the air-to-coolant heat exchanger has an inlet for the air heated or cooled by the first heat pump, with the first air duct directing the air directly into the inlet. Furthermore, the air-to-coolant heat exchanger has an outlet to discharge the exiting air.

[0017] A particularly advantageous feature of the coolant circuit is the inclusion of a second heat pump, which can also be elastocaloric and thus comprise an elastocaloric material. This second heat pump is therefore also capable of heating or cooling air. Specifically, the second heat pump has an intake and exhaust air connection to the outside air, allowing it to heat and cool outside air independently of the first heat pump. The thermal management system can be configured to direct the air heated or cooled by the second heat pump into the air-to-coolant heat exchanger. This can be achieved, for example, via a suitable duct. The second heat pump serves primarily for supplementary cooling, such as during fast battery charging. Furthermore, the coolant circuit can include a connection to an external cooling system, such as a charging station.The external column, especially the charging station, can provide cold coolant that can absorb the heat from the battery, especially during fast charging.

[0018] The thermal management system can further include a second air duct for returning air exiting the air-coolant heat exchanger to the first heat pump, so that this air can be used to cool or heat the vehicle's interior. The air returned to the first heat pump via the second air duct can be used for heat transfer instead of, or in addition to, the outside air. The second air duct thus allows the air exiting the air-coolant heat exchanger to be used as a heat source for the interior.

[0019] The thermal management system can, in particular, include a control unit that, depending on the temperature of the outgoing air, directs it to the outside air or the second air duct. This can occur depending on the operating mode of the first heat pump.

[0020] The thermal management system can primarily include sensors that measure and compare both the temperature of the exhaust air and the ambient temperature. In cooling mode, the exhaust air is recirculated to the first heat pump, particularly when its temperature is lower than the ambient temperature. Ambient temperature refers specifically to the temperature of the outside air, i.e., the air surrounding the vehicle. In heating mode, the air is recirculated when its temperature is higher than the ambient temperature. This allows existing heat energy, which would otherwise be released into the outside air, to be used for heating or cooling the interior. This also applies to cooling mode. In other words, the air exiting the air-coolant heat exchanger can be used as a heat source or heat sink for the first heat pump.Energy efficiency is therefore also optimized in this context.

[0021] In a further aspect, the present invention comprises a method for thermal management of a motor vehicle battery, which uses a thermal management system as described above. This method particularly includes controlling the recirculation of air exiting the air-coolant heat exchanger to the first heat pump, depending on the temperature of the exiting air compared to the outside air and on the operating mode of the first heat pump. In a further aspect, the invention comprises a motor vehicle with a thermal management system as described above.

[0022] They show in a purely schematic representation Fig. 1: a thermal management system according to the invention in cooling mode; Fig. 2: the thermal management system of the Fig. 1; Fig. 3: the thermal management system of the Fig. 1 and Fig. 2 in heating mode; Fig. 4: another thermal management system; Fig. 5: the thermal management system of the Fig. 4; and Fig. 6: another thermal management system.

[0023] Fig. Figure 1 shows a thermal management system 10 according to the invention, comprising a first air circuit 11. The first air circuit 11 comprises a first heat pump 12. The first heat pump 12 is elastocaloric and thus comprises an elastocaloric material. The first heat pump 12 has an air connection to the outside air 40 and an air connection to the interior 14 of the vehicle. Outside air 40 and air from the interior 14, in other words cabin air, are supplied directly to the elastocaloric heat pump without first passing through a heat exchanger. Thus, in Fig. 1 outside air to be taken in 44 and air to be released to the outside air 45 can be seen.

[0024] The first heat pump 12 supplies air to the interior and can also draw air back from the interior. Fig. Figure 1 shows a cooling mode of the first heat pump 12, such that the first heat pump 12 supplies cooled air 41 to the interior. Reference symbol 43, on the other hand, denotes air to be returned to the first heat pump 12. Fig. 1 represents the cooling mode, the air 45 released to the outside air 40 is significantly warmer than the outside air 44 taken in.

[0025] Air 41, cooled by the first heat pump, is not only supplied to the interior 14, but also to a first air duct 13, which leads to an air-coolant heat exchanger 25 of a coolant circuit 21. The air-coolant heat exchanger 25 receives the air 41 cooled by the first heat pump 12 and uses it indirectly to cool the battery 20. For this purpose, the coolant circuit 21 includes a pump 23. Specifically, the air-coolant heat exchanger 25 uses the air 41 cooled by the first heat pump 12 to cool the coolant 50, which is then supplied to the battery 20, where the coolant 50 cools the battery 20. After cooling, the coolant 50, which has warmed up, is returned to the air-coolant heat exchanger 25 by the pump 23.

[0026] The air 41 cooled by the first heat pump 12 thus enters the air-coolant heat exchanger 25 and is thus transferred to Fig. 2 also referred to as air 46 entering the air-coolant heat exchanger. Air 47 exiting the air-coolant heat exchanger 25 is released to the outside air 40, since in Fig. 1 the case is shown in which the temperature of the air 47 exiting the air-coolant heat exchanger 25 is higher than the outside temperature.

[0027] It should also be noted that warmer air or warmer coolant in Fig. Figure 1 and the other figures are visually distinguished by hatching.

[0028] In Fig. 2 is the thermal management system 10 of the Fig. Figure 1 illustrates a case where the temperature of the air 47 exiting the air-coolant heat exchanger 25 is lower than the outside temperature. Instead of releasing the air 47 exiting the air-coolant heat exchanger 25 to the outside air 40, it is guided back to the first heat pump 12 via the second air duct 24 and used to cool the interior 14. It is not supplied directly to the interior 14, but is fed to the first heat pump 12, which cools it and then supplies it to the interior 14.

[0029] Fig. 3 represents the thermal management system 10 of the Fig. 1 and Fig. 2 in heating mode, so that heated air 42 is supplied to the interior 14 by means of the first heat pump. Heated air 42 is also directed to the air-coolant heat exchanger 25 via the first air duct 13. Its heat is used to heat the coolant 50 and thus to heat the battery 20.

[0030] The air 47 exiting the air-coolant heat exchanger 25 can either be released to the outside air 40 or supplied to the first heat pump 12 via the second air duct 24. In this process, Fig. 3 both possibilities are shown. Recirculation occurs in particular when the temperature of the air 47 exiting the air-coolant heat exchanger 25 is higher than the outside temperature. Since the air 47 during recirculation is between the temperature of the air 41 heated by the first heat pump and the temperature of the outside air 40, it is in Fig. 3 shown again with different hatching.

[0031] Fig. 4 represents another thermal management system 10, which, apart from the following differences, is analogous to the thermal management system 10 of the Fig. 1 is designed. A second heat pump 22 is located in the coolant circuit 21. The second heat pump 22 is designed to draw in outside air and release outside air again. The second heat pump 22 can thus cool or heat the battery 20 independently of the first heat pump 12. This serves as supplementary cooling, especially during fast charging of the battery 20. The second heat pump 22 thus transfers already cooled air to the air-coolant heat exchanger 25 for cooling the battery 20. The air 47 exiting the air-coolant heat exchanger 25 is in Fig. 4. Coolant is released to the outside air, as its temperature is higher than the outside temperature. Furthermore, the coolant circuit 21 may have a connection to an external cooling system that provides coolant for cooling the battery 20.

[0032] Fig. 5 represents the thermal management system 10 of the Fig. 4 in the case that the temperature of the air 47 exiting the air-coolant heat exchanger 25 is higher than the outside temperature, so that it is supplied to the second air guide path 24.

[0033] In Fig. Figure 6 shows another thermal management system, analogous to thermal management system 10. Fig. 3 is configured, except for the following difference: The first air duct 13 is designed to directly cool the battery 20 with the heated air 42. The air 42 is therefore not directed into an air-coolant heat exchanger 25, but rather direct heat transfer with the battery 20 takes place. The air 48 after heat transfer with the battery 20 can be supplied to the outside air 40 if its temperature is lower than the outside temperature, or to the first heat pump 12 if its temperature is higher than the outside temperature. Fig. Figure 6 represents both cases. Reference symbol list 10 Thermal management system 11 first air circuit 12 first heat pump 13 first air guidance route 14 Interior 20 batteries 21 Coolant circuit 22 second heat pump 23 Pump 24 second air guidance route 25 air-to-coolant heat exchangers 40 outside air 41 air cooled by the first heat pump 42 air heated by the first heat pump 43 air returned to first heat pump 44 outdoor air recorded 45% of air released into the outside air 46 Air entering air-coolant heat exchanger 47 Air exiting from air-coolant heat exchanger 48 Air after heat transfer with battery 50 Coolant

Claims

[1] Thermal management system (10) for a battery (20) of a motor vehicle, wherein the thermal management system (10) comprises a first air circuit (11) for heating or cooling an interior (14) of the vehicle, wherein the first air circuit (11) includes a first heat pump (12), wherein the first heat pump (12) is elastocaloric and comprises an elastocaloric material, characterized by , that the first heat pump (12) is designed to heat or cool air, and the thermal management system (10) comprises a first air duct (13) from the first heat pump (12) to the battery (20) of the motor vehicle and / or to a coolant circuit (21) of the battery (20) in order to use air heated or cooled by means of the first heat pump (12) for heating or cooling the battery (20). [2] Thermal management system (10) according to claim 1, characterized by, that the first air duct (13) directs the air heated or cooled by means of the first heat pump (12) directly to the battery (20) for direct heat transfer. [3] Thermal management system (10) according to claim 1, characterized by , that the coolant circuit (21) of the battery (20) comprises a coolant (50) and an air-coolant heat exchanger (25), wherein the first air guide path (13) directs the air heated or cooled by means of the first heat pump (12) to the air-coolant heat exchanger (25) for heat transfer to the coolant (50). [4] Thermal management system (10) according to claim 3, characterized by , that the coolant circuit (21) includes a second heat pump (22) and / or a connection to an external cooling system, wherein the second heat pump (22) is designed to heat or cool air, wherein the thermal management system (10) is designed to guide heated or cooled air by means of the second heat pump (22) into the air-coolant heat exchanger (25) for heat transfer to the coolant (50), and wherein the external cooling provides coolant for cooling the battery (20). [5] Thermal management system (10) according to one of claims 3 or 4, characterized by , that the thermal management system (10) includes a second air duct (24) for returning air (47) exiting the air-coolant heat exchanger (25) to the first heat pump (12) in order to use it for cooling or heating the interior. [6] Thermal management system (10) according to one of claims 3, 4 or 5, characterized by , that the thermal management system (10) includes a control unit, wherein the control unit is designed to supply the air (47) exiting the air-coolant heat exchanger (25) to the outside air or to the second air guide path (24) depending on the temperature of the air (47) exiting the air-coolant heat exchanger (25). [7] Thermal management system (10) according to claim 6, characterized by , that the control unit is designed to in a heating mode of the first heat pump (12) to supply the air (47) exiting the air-coolant heat exchanger (25) to the second air duct (24) when its temperature exceeds an outside temperature. [8] Thermal management system (10) according to one of claims 6 or 7, characterized by , that the control unit is designed to in a cooling mode of the first heat pump (12) to supply the air (47) exiting the air-coolant heat exchanger (25) to the second air duct (24) when its temperature falls below an outside temperature. [9] Method for thermal management for a battery (20) of a motor vehicle, characterized by , that the method is carried out with a thermal management system (10) according to one of claims 1 to 8. [10] Motor vehicle with a thermal management system (10) according to any one of claims 1 to 8.

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