Method for operating a thermal management system for a motor vehicle

Abstract

Method for operating a thermal management system (1) for a motor vehicle, comprising a control unit, a first temperature control section (T1), a second temperature control section (T2), a first pump (P1), a second pump (P2), and a valve arrangement (2), wherein the first temperature control section (T1), the second temperature control section (T2), the first pump (P1), and the second pump (P2) are each connected to the valve arrangement (2), wherein the valve arrangement (2) can be switched into a first switching position (S1) and a second switching position (S2) by means of the control unit, wherein the first pump (P1) can be fluidically connected to the first temperature control section (T1) and the second pump (P2) can be fluidically connected to the second temperature control section (T2) by means of the valve arrangement (2) in the first switching position (S1), thereby forming a respective temperature control circuit.wherein, by means of the valve arrangement (2) in the second switching position (S2), the first pump (P1) is fluidically connectable to the second temperature control section (T2) and the second pump (P2) is fluidically connectable to the first temperature control section (T1), forming a respective temperature control circuit, characterized in that the valve arrangement (2) is switched to the first switching position (S1) by means of the control unit when the temperature control requirements of the first temperature control section (T1) can be implemented by means of the first pump (P1) and the temperature control requirements of the second temperature control section (T2) can be implemented by means of the second pump (P2), and the valve arrangement (2) is switched to the second switching position (S2) by means of the control unit when the temperature control requirements of the first temperature control section (T1) can be implemented by means of the second pump (P2) and the temperature control requirements of the second temperature control section (T2) can be implemented by means of the first pump (P1).

Description

[0001] The invention relates to a method for operating a thermal management system for a motor vehicle, in particular for an electric vehicle or a hybrid electric vehicle, with the features of the preamble of claim 1.

[0002] Such thermal management systems (see DE 10 2019 207 993 A1) comprise a control unit and various temperature control sections, in particular a first temperature control section and a second temperature control section, as well as associated pumps, in particular a first pump and a second pump. The temperature control sections and the pumps are each connected to a valve arrangement of the thermal management system. The valve arrangement can be switched to a first switching position and a second switching position by means of the control unit. This enables different types of flow through the temperature control sections. The temperature control sections each have corresponding flow channels through which a heat transfer fluid can be conveyed. A unit connected to these flow channels can be temperature-controlled, in particular cooled, by means of the heat transfer fluid. The temperature control sections can also be designed as flow circuits.

[0003] From DE 10 2020 206 268 A1, for example, a thermal management system for a motor vehicle battery, in particular for an electric vehicle, a battery-electric vehicle, or a hybrid electric vehicle, is known. The thermal management system comprises a control unit and a first coolant circuit, wherein the first coolant circuit includes a battery, a chiller, and a first pump. A coolant fluid can be circulated through the first coolant circuit, and thus through the battery and the chiller, by means of the first pump. The thermal management system further comprises a second coolant circuit, wherein the second coolant circuit includes an auxiliary heater, a heat exchanger, and a second pump. The coolant fluid can therefore be circulated through the second coolant circuit, and thus through the auxiliary heater and the heat exchanger, by means of the second pump.The first and second coolant circuits are thermally or thermofluidically coupled via a coupling device. The control unit is designed to regulate the output of the first and second pumps to meet the thermal management requirements. The coupling device includes, for example, a 3-way valve and a pipe connection between the first and second coolant circuits. The coupling device is designed as a valve assembly. The 3-way valve regulates the coolant exchange between the second and first coolant circuits. A coolant return line serves to return coolant from the first to the second coolant circuit. Furthermore, a check valve is provided in the first coolant circuit to prevent coolant flow from the auxiliary heater to the chiller.

[0004] To supply or remove the required heat depending on the demand or operating condition of each temperature control section or coolant circuit, each section or coolant circuit requires a peak pump output that can be achieved at maximum pump utilization. The pump installed in each temperature control section or coolant circuit is therefore determined by the peak demand. For multiple temperature control sections or coolant circuits, the pumps are installed with the maximum required output. However, in normal operation, the required output is significantly lower, in particular approximately 20-30% lower, and the operating conditions do not require the peak output of the corresponding pump in all coolant circuits simultaneously. This results in high material costs, as the pump with the correspondingly high peak output must always be installed.These particularly powerful pumps are then operated in an inefficient performance range during normal operation, resulting in correspondingly high energy consumption.

[0005] The invention is therefore based on the objective of designing and / or further developing the thermal management system for a motor vehicle and the method for operating the thermal management system in such a way that the problems of the prior art are avoided or at least reduced. In particular, the material costs of the thermal management system and the energy consumption during its operation are to be reduced.

[0006] This problem underlying the invention is solved by a method for operating a thermal management system for a motor vehicle with the features of claim 1.

[0007] One aspect of the invention is that, by means of the valve arrangement, the first pump can be fluidically connected to the first temperature control section and the second pump to the second temperature control section in the first switching position, forming a respective temperature control circuit. Furthermore, in the second switching position, the first pump can be fluidly connected to the second temperature control section and the second pump to the first temperature control section in the second switching position. According to the invention, the valve arrangement is switched to the first switching position by means of the control unit when the temperature control requirements of the first temperature control section can be met by the first pump and the temperature control requirements of the second temperature control section can be met by the second pump.Furthermore, the valve arrangement is switched to the second switching position by means of the control unit if the temperature control requirements of the first temperature control section can be met by the second pump and the temperature control requirements of the second temperature control section can be met by the first pump.

[0008] The two pumps are preferably of different types or designs. The pumps are not permanently assigned to one of the temperature control sections. By switching the valve arrangement to one of the two switching positions, each temperature control section can be fluidically coupled to the pump best suited to meet the respective temperature control requirement, with "best suited" referring in particular to the efficiency of the pump operation. The thermal management system thus operates more efficiently, thereby reducing its energy consumption during operation.

[0009] The valve arrangement is preferably switched by the control unit in such a way as to achieve the maximum possible efficiency of the thermal management system, in particular of the two pumps. The thermal management system is thus operated particularly efficiently and with low energy consumption.

[0010] Preferably, the valve arrangement comprises a first valve and a second valve. The first temperature control section is connected to a first inlet of the first valve and a first outlet of the second valve. The second temperature control section is connected to a second inlet of the first valve and a second outlet of the second valve. Thus, each of the two temperature control sections is connected to the first valve on the inlet side and to the second valve on the outlet side. The two valves make the valve arrangement particularly simple and cost-effective. Furthermore, controlling the two valves is straightforward.

[0011] According to an advantageous embodiment of the method, the two valves are switched to either the first or the second switching position by means of the control unit. The first switching position of the valve arrangement then corresponds to the respective first switching position of the two valves, and the second switching position of the valve arrangement corresponds to the respective second switching position of the two valves. This further simplifies the method, thus reducing the effort required to develop the control unit, particularly the creation of corresponding control software.

[0012] Preferably, the first pump is connected to a first outlet of the first valve and a first inlet of the second valve. The second pump is preferably connected to a second outlet of the first valve and a second inlet of the second valve. The two pumps are thus fluidically arranged between the two valves. With such a configuration, the two valves and the two pumps can be arranged in a small installation space.

[0013] According to an advantageous embodiment of the thermal management system, both valves are designed as 4 / 2-way valves. In a first switching position, each 4 / 2-way valve allows flow from its respective first inlet to its respective first outlet and from its respective second inlet to its respective second outlet. In a second switching position, each 4 / 2-way valve allows flow from its respective first inlet to its respective second outlet and from its respective second inlet to its respective first outlet. The flow channels within the 4 / 2-way valves are separated from each other; that is, the fluid supplied via the respective first inlet does not mix with the fluid supplied via the respective second inlet. 4 / 2-way valves are inexpensive to procure and easy to control.Preferably, the 4 / 2-way valves are each switchable by means of an actuator. Preferably, the 4 / 2-way valves are each held in one of the switching positions by a spring when the actuator is not energized, this preferably being the switching position that occurs more frequently during operation of the thermal management system. The 4 / 2-way valves are preferably of identical construction.

[0014] Advantageously, both the first and second temperature control sections each have at least one component to be temperature-controlled, such as a battery or a heat exchanger. A heat transfer fluid can be circulated through the respective component for temperature control by either the first or second pump. Depending on the operating conditions, the component can be cooled or heated by the heat transfer fluid. A corresponding heat transfer occurs between the heat transfer fluid and the respective component. For example, the battery can thus always be kept at the temperature required for its proper operation. In particular, overheating of the battery can be reliably prevented.

[0015] In another embodiment of the thermal management system, the rated power of the first pump is greater than that of the second pump. The rated power refers to the maximum power achievable by each pump during continuous operation. However, the pumps can also be operated at lower power levels if this is advantageous for achieving the desired temperature control of the units. Pumps with different rated powers exhibit optimal efficiency at different operating speeds, particularly in a range close to their rated power. The valve arrangement is then preferably always configured to achieve the maximum possible efficiency when both pumps are used together. With pumps of different rated power, this maximum possible efficiency is particularly high during operation of the thermal management system.

[0016] According to a further, particularly preferred embodiment of the thermal management system, the rated power of the second pump is lower than the peak pump power required for both the first and second temperature control sections. This is both possible and advantageous because, during normal operation of the thermal management system, the required power is significantly lower, in particular approximately 20-30% lower, than the peak pump power. Furthermore, typical operating conditions do not require the peak power of the associated pumps simultaneously in all temperature control sections. Therefore, even though the rated power of the second pump is lower than the peak pump power required for both the first and second temperature control sections, the temperature control requirements can still be met in all typical operating conditions. The lower rated power of the second pump also reduces the cost of procuring the pumps. For example, a temperature control requirement could be...This means that a specific unit should have a temperature within a specific temperature range.

[0017] Preferably, the thermal management system includes a third temperature control section and a third pump. The third temperature control section and the third pump are each connected to the valve assembly. The valve assembly is designed to alternately connect each pump to different temperature control sections, thereby forming a separate temperature control circuit, by implementing specific switching positions. The pumps and temperature control sections are designated as first, second, and third pumps, respectively, for the sake of clarity. The thermal management system can be expanded analogously with additional pumps and temperature control sections.

[0018] There are now numerous possibilities for advantageously designing and further developing the method for operating the thermal management system. Reference is first made to the claims subordinate to claim 1. In the following, a preferred embodiment of the thermal management system for a motor vehicle and the method for operating the thermal management system will be explained and described in more detail with reference to the drawing and the accompanying description. The drawing shows: Fig. 1. A schematic representation of a hydraulic circuit diagram of an embodiment of the thermal management system for a motor vehicle with a valve arrangement in a first switching position, and Fig. 2. A schematic representation of a hydraulic circuit diagram of the exemplary embodiment of the thermal management system for a motor vehicle. Fig. 1 with the valve arrangement in a second switching position.

[0019] Fig. 1 and Fig. Figures 2 each show a thermal management system 1 for a motor vehicle, in particular for an electric vehicle or a hybrid electric vehicle, comprising a control unit, a first temperature control section T1, a second temperature control section T2, a first pump P1, a second pump P2, and a valve assembly 2. The first temperature control section T1, the second temperature control section T2, the first pump P1, and the second pump P2 are each connected to the valve assembly 2. The valve assembly 2 can be switched to a first switching position S1 and a second switching position S2 by means of the control unit (not shown). The pumps P1 and P2 are designed as hydraulic pumps, e.g., as vane pumps, gear pumps, axial piston pumps, or similar. The temperature control sections T1 and T2 have flow channels which are formed in housing components and / or by means of pipes and / or hoses.The control unit is connected to the valve arrangement 2 via control lines. In particular, control signals can be transmitted to at least one actuator of the valve arrangement 2.

[0020] By means of the valve arrangement 2 in the first switching position S1, the first pump P1 can be fluidically connected to the first temperature control section T1 and the second pump P2 to the second temperature control section T2, forming their respective temperature control circuits. The heat transfer fluid pumped by the first pump P1 can then be conveyed from an outlet of the first pump P1 through the first temperature control section T1 to an inlet of the first pump P1. The heat transfer fluid pumped by the second pump P2 can then be conveyed from an outlet of the second pump P2 through the second temperature control section T2 to an inlet of the second pump P2. The pumps P1 and P2 are preferably each driven by an electric motor E, which can be supplied with electrical energy via a battery. Alternatively, the use of other types of motors, such as hydraulic motors, would also be conceivable.

[0021] By means of the valve arrangement 2 in the second switching position S2, the first pump P1 can be fluidically connected to the second temperature control section T2, and the second pump P2 to the first temperature control section T1, forming their respective temperature control circuits. The heat transfer fluid pumped by the first pump P1 can then be conveyed from an outlet of the first pump P1 through the second temperature control section T2 to an inlet of the first pump P1. The heat transfer fluid pumped by the second pump P2 can then be conveyed from an outlet of the second pump P2 through the first temperature control section T1 to an inlet of the second pump P2. The respective temperature control circuits are separate from each other; fluid exchange between the temperature control circuits is not initially intended. One of the resulting temperature control circuits is in Fig. 1 and Fig.2 are each symbolized with a dashed line, and the other developing temperature control cycle is symbolized with a solid line.

[0022] The first and second pumps, P1 and P2, can be selectively and reversibly connected to the two temperature control sections, T1 and T2. This ensures that the pump P1 or P2 can always be connected to the temperature control section T1 or T2 that best meets the temperature control requirements of that section, particularly with regard to high energy efficiency.

[0023] Valve arrangement 2 comprises a first valve V1 and a second valve V2. The first temperature control section T1 is connected to a first inlet V1E1 of the first valve V1 and a first outlet V2A1 of the second valve V2. The second temperature control section T2 is connected to a second inlet V1E2 of the first valve V1 and a second outlet V2A2 of the second valve V2. Alternatively, the valve arrangement could also have only one valve or more than two valves.

[0024] The first pump P1 is connected to a first outlet V1A1 of the first valve V1 and a first inlet V2E1 of the second valve V2. The second pump P2 is connected to a second outlet V1A2 of the first valve V1 and a second inlet V2E2 of the second valve V2.

[0025] The two valves V1 and V2 are each designed as 4 / 2-way valves. In a first switching position S1, each 4 / 2-way valve establishes a flow connection from the respective first inlet V1E1, V2E1 to the respective first outlet V1A1, V2A1, and from the respective second inlet V1E2, V2E2 to the respective second outlet V1A2, V2A2. In a second switching position S2, each 4 / 2-way valve establishes a flow connection from the respective first inlet V1E1, V2E1 to the respective second outlet V1A2, V2A2, and from the respective second inlet V1E2, V2E2 to the respective first outlet V1A1, V2A1. Each 4 / 2-way valve preferably has an actuator for its actuation, with the actuators being connected to the control unit. The actuators are designed, for example, as electric linear actuators.The linear actuators are preferably held in one of the switching positions S1, S2 by a spring tension and are moved to the respective other switching position S1, S2 when the linear actuator is energized or subsequently held in this other switching position S1, S2.

[0026] The first temperature control section T1 and the second temperature control section T2 each have at least one component A1, A2 to be temperature controlled, such as a battery or a heat exchanger. The component A1, A2 to be temperature controlled could also be an electric machine, in particular a rotor and / or a stator of the electric machine. A heat transfer fluid can be pumped through the respective component A1, A2 for temperature control by means of the first or the second pump P1, P2. As the heat transfer fluid flows through the respective component A1, A2, heat transfer, in particular of a convective nature, occurs between the heat transfer fluid and the respective component A1, A2. The extent of the heat transfer depends not only on the temperature but also, in particular, on the mass flow rate of the heat transfer fluid and thus on the current pumping capacity of the associated pump P1, P2.

[0027] The rated power of the first pump, P1, is higher than that of the second pump, P2. If pumps P1 and P2 are operated significantly below their rated power, for example, at 70-80% of their rated power, only a lower efficiency can be achieved compared to operation at rated power. Since two pumps, P1 and P2, with different rated powers are available for each temperature control section, T1 and T2, both pumps P1 and P2 can be operated near their respective rated powers and thus with high efficiency for many of the temperature control requirements that arise during the operation of the thermal management system 1, which are associated with the desired heat transfers described above.

[0028] The rated power of the second pump P2 is less than the peak pumping power required by the first and second temperature control sections T1 and T2, respectively. Therefore, the number of operating points in which both pumps P1 and P2 can be operated close to their respective rated power and thus with high efficiency can be further increased. This is because the peak pumping power is only required, if at all, in one of the temperature control sections T1 and T2, and not in both simultaneously.

[0029] It is conceivable that the thermal management system includes a third temperature control section and a third pump. The third temperature control section and the third pump are each connected to the valve assembly, which is then configured to alternately connect each pump to different temperature control sections, thus creating a separate temperature control circuit, by implementing various switching positions. The valve assembly is then designed accordingly. For example, analogous to the two 4 / 2-way valves, two 6 / 6-way valves are provided, enabling, for example, the following flow patterns: If the first pump supplies the first temperature control section with heat transfer fluid, the second pump supplies the second or third temperature control section, and the third pump supplies the third or second temperature control section.If the second pump supplies the first temperature control section with heat transfer fluid, the first pump supplies the second or third temperature control section, and the third pump supplies the third or second temperature control section. If the third pump supplies the first temperature control section with heat transfer fluid, the first pump supplies the second or third temperature control section, and the second pump supplies the third or second temperature control section.

[0030] However, it is also conceivable to design the valve arrangement or its valves differently. Furthermore, more than three pumps and more than three temperature control sections could be provided.

[0031] In the operating procedure of the previously described thermal management system 1, the valve arrangement 2 is switched to the first switching position S1 by the control unit when the temperature control requirements of the first temperature control section T1 can be met by the first pump P1 and the temperature control requirements of the second temperature control section T2 can be met by the second pump P2. The valve arrangement 2 is switched to the second switching position S2 by the control unit when the temperature control requirements of the first temperature control section T1 can be met by the second pump P2 and the temperature control requirements of the second temperature control section T2 can be met by the first pump P1.

[0032] The control unit is primarily used to control and / or regulate the output of pumps P1 and P2. To determine the temperature control requirements and the output of pumps P1 and P2, the temperatures of units A1 and A2 and / or the heat transfer fluid are measured at appropriate points. The measured values ​​are then used by the control unit to determine the temperature control requirements and the corresponding output of pumps P1 and P2, in order to subsequently send appropriate control signals to pumps P1 and P2, particularly to their electric motors E. If the temperature control requirements of both temperature control sections T1 and T2 can be met by both pumps P1 and P2, the pumps are assigned to the temperature control sections T1 and T2 in such a way that the combined energy consumption of both pumps P1 and P2 is minimized.

[0033] The two valves V1 and V2 are switched to their respective positions S1 and S2 by the control unit. For this purpose, corresponding control signals are generated by the control unit and sent to the actuators of the two valves V1 and V2. Either each valve V1 and V2 has a separate actuator, or both valves V1 and V2 can be switched by the same actuator. In both cases, the preferably identical valves V1 and V2 are preferably switched simultaneously from the first position S1 to the second position S2, or vice versa. Reference symbol list 1 Thermal management system 2 Valve arrangement T1 first temperature control section T2 second temperature control section P1 first pump P2 second pump V1 first valve V2 second valve S1 first switching position S2 second switching position V1E1 first intake of the first valve V1 V1E2 second inlet of the first valve V1 V1A1 first outlet of the first valve V1 V1A2 second outlet of the first valve V1 V2E1 first inlet of the second valve V2 V2E2 second inlet of the second valve V2 V2A1 first outlet of the second valve V2 V2A2 second outlet of the second valve V2 A1, the unit to be tempered in the first tempering section T1 A2, the unit to be tempered in the second tempering section T2 E electric motor

Claims

[1] Method for operating a thermal management system (1) for a motor vehicle comprising a control unit, a first temperature control section (T1), a second temperature control section (T2), a first pump (P1), a second pump (P2) and a valve arrangement (2), wherein the first temperature control section (T1), the second temperature control section (T2), the first pump (P1) and the second pump (P2) are each connected to the valve arrangement (2), wherein the valve arrangement (2) can be switched into a first switching position (S1) and a second switching position (S2) by means of the control unit, wherein, in the first switching position (S1), the first pump (P1) can be fluidically connected to the first temperature control section (T1) and the second pump (P2) to the second temperature control section (T2) by means of the valve arrangement (2), forming a respective temperature control circuit.wherein, by means of the valve arrangement (2) in the second switching position (S2), the first pump (P1) can be fluidically connected to the second temperature control section (T2) and the second pump (P2) to the first temperature control section (T1) by forming a respective temperature control circuit, characterized by , that the valve arrangement (2) is switched to the first switching position (S1) by means of the control unit when the temperature control requirements of the first temperature control section (T1) can be met by means of the first pump (P1) and the temperature control requirements of the second temperature control section (T2) can be met by means of the second pump (P2), and that the valve arrangement (2) is switched to the second switching position (S2) by means of the control unit when the temperature control requirements of the first temperature control section (T1) can be met by means of the second pump (P2) and the temperature control requirements of the second temperature control section (T2) can be met by means of the first pump (P1). [2] Method according to claim 1, characterized by , that the valve arrangement (2) has a first valve (V1) and a second valve (V2), wherein the first temperature control section (T1) is connected to a first inlet (V1E1) of the first valve (V1) and a first outlet (V2A1) of the second valve (V2), wherein the second temperature control section (T2) is connected to a second inlet (V1E2) of the first valve (V1) and a second outlet (V2A2) of the second valve (V2). [3] Method according to claim 2, characterized by , that the first pump (P1) is connected to a first outlet (V1A1) of the first valve (V1) and a first inlet (V2E1) of the second valve (V2), wherein the second pump (P2) is connected to a second outlet (V1A2) of the first valve (V1) and a second inlet (V2E2) of the second valve (V2). [4] Method according to claim 2 or 3, characterized by, that the two valves (V1, V2) are each designed as 4 / 2-way valves, wherein a flow connection from the respective first inlet (V1E1, V2E1) to the respective first outlet (V1A1, V2A1) and from the respective second inlet (V1E2, V2E2) to the respective second outlet (V1A2, V2A2) can be realized by means of each 4 / 2-way valve in a first switching position (S1), wherein a flow connection from the respective first inlet (V1E1, V2E1) to the respective second outlet (V1A2, V2A2) and from the respective second inlet (V1E2, V2E2) to the respective first outlet (V1A1, V2A1) can be realized by means of each 4 / 2-way valve in a second switching position (S2). [5] Method according to any of the preceding claims, characterized by, that the first temperature control section (T1) and the second temperature control section (T2) each have at least one unit (A1, A2) to be temperature controlled, such as a battery or a heat exchanger, wherein a heat transfer fluid can be pumped by the first or the second pump (P1, P2) for its temperature control through the respective unit (A1, A2). [6] Method according to any of the preceding claims, characterized by , that the rated power of the first pump (P1) is greater than the rated power of the second pump (P2). [7] Method according to any of the preceding claims, characterized by , that the nominal power of the second pump (P2) is less than the respective required peak pump power of the first and second temperature control sections (T1, T2). [8] Method according to any of the preceding claims, characterized by, that the thermal management system (1) has a third temperature control section and a third pump, wherein the third temperature control section and the third pump are each connected to the valve arrangement (2), wherein the valve arrangement (2) is designed to connect each pump to different temperature control sections in a fluid flow by implementing respective switching positions alternately, forming a respective temperature control circuit. [9] Method according to claim 2 or any of the claims dependent on claim 2, characterized by , that the two valves (V1, V2) are switched to the first switching position (S1) or to the second switching position (S2) by means of the control unit.

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