Cooling system for a motor vehicle and motor vehicle with such a cooling system

Abstract

Cooling system (1) for a motor vehicle, with an electrical energy storage device (7) for powering the motor vehicle; a chiller (6) which is connected to a refrigeration circuit (8) and is fluidically separated from it by a main cooling circuit, in order to transfer heat energy between the refrigeration circuit (8) and the main cooling circuit; one or more actuators (11, 12); at least one heat source (5), and one or more ambient air coolers (2a, 2b), wherein In a first operation, the actuators (11, 12) configure the main cooling circuit in such a way that the chiller (6), the energy storage (7) and none of the ambient air coolers (2a, 2b) can be permeated by it; In a second operation, the actuators (11, 12) configure the main cooling circuit such that the chiller (6), the energy storage unit (7) and at least one of the ambient air coolers (2a, 2b) can flow through it, and In a third operation, the actuators (11, 12) configure the main cooling circuit such that the chiller (6), at least one of the ambient air coolers (2a, 2b) and the heat source (5) can flow through it, wherein in the first operation and / or in the second operation the actuators (11, 12) additionally configure a secondary cooling circuit through which the heat source (5) and at least one of the ambient air coolers (2a) can flow, wherein in the second operation the main cooling circuit opens into the secondary cooling circuit downstream of the energy storage (7), so that the main cooling circuit and the secondary cooling circuit overlap section by section.

Description

[0001] The invention relates to a cooling system for a motor vehicle, with an electrical energy storage device for powering the motor vehicle, and to a motor vehicle with such a cooling system.

[0002] The following methods are currently common for cooling an electrical energy storage system in a hybrid or electric vehicle. One option is air cooling using ambient air or air conditioned via the refrigeration circuit. Another possibility is coolant cooling, where the energy storage system is cooled by a coolant. The coolant is conditioned by an ambient air cooler or the refrigeration circuit, the latter requiring a chiller. A chiller is a coolant-refrigerant heat exchanger in which thermal energy is transferred between a cooling circuit and a refrigerant circuit, which are fluidically separated. A further option for cooling the energy storage system is direct refrigerant cooling, where the energy storage system is cooled directly via the refrigeration circuit.The refrigerant evaporates in evaporator plates that are located directly on the energy storage cell modules.

[0003] The disadvantage of this state of the art is that cooling the energy storage system without the support of a refrigeration circuit does not have sufficient power, especially at high ambient temperatures; this is particularly true for applications such as DC fast charging, dynamic driving maneuvers, or high driving speeds.

[0004] If cooling is achieved using a refrigeration cycle, the cycle provides cooling capacity for both the interior and the energy storage system. Due to the increased cooling demands of the energy storage system, the cooling capacity is insufficient in some operating conditions (e.g., high driving speeds, DC fast charging). Furthermore, it must be considered that the power of the electric refrigerant compressor must be dissipated via the cooling system in addition to the actual cooling capacity. This results in an additional load on the entire cooling system (for example, if the energy storage system requires 2 kW of cooling capacity and the refrigerant compressor draws 1 kW, the resulting condenser power is 3 kW). Therefore, cooling the energy storage system using a refrigeration cycle is not energy-efficient in every operating condition.

[0005] For further information on the state of the art, reference is made to DE 10 2009 021 530 A1, DE 10 2009 054 186 A1, DE 10 2010 042 122 A1 and DE 10 2011 016 070 A1.

[0006] It is an object of the present invention to provide an improved, and in particular more efficient, cooling system for a motor vehicle which has an electrical energy storage device. This object is achieved by a cooling system according to claim 1 and a motor vehicle according to claim 8. Advantageous embodiments of the invention are the subject of the dependent claims.

[0007] According to one embodiment of the invention, a cooling system for a motor vehicle is provided, comprising an electrical energy storage device for powering the motor vehicle; a chiller, through which a refrigeration circuit and a main cooling circuit can flow in a fluidically separate manner, in order to transfer heat energy between the refrigeration circuit and the main cooling circuit; one or more actuators; at least one heat source; and one or more ambient air coolers, wherein in a first operation the actuators configure the main cooling circuit such that the chiller, the energy storage device, and none of the ambient air coolers can flow through it;In a second operating mode, the actuators configure the main cooling circuit such that the chiller, the energy storage unit, and at least one of the ambient air coolers can flow through it, and in a third operating mode, the actuators configure the main cooling circuit such that the chiller, at least one of the ambient air coolers, and the heat source can flow through it. This embodiment offers the advantage that an ambient air cooler, a chiller, and an electrical energy storage unit can be connected to each other differently as needed, thus enabling demand-based and energy-efficient cooling.

[0008] According to a further embodiment of the invention, in the third operating mode, the chiller is arranged downstream of the heat source and upstream of the at least one ambient cooler. Because the chiller is arranged downstream of potential heat sources, the waste heat from these heat sources can be transferred via the chiller into the refrigeration circuit and thus be available for potential heat pump applications for energy-efficient heating of the interior and / or the energy storage system. Because the chiller is arranged upstream of the ambient cooler, the refrigerant can be cooled below ambient temperature, allowing heat from the environment to be absorbed into the main refrigeration circuit and transferred via the chiller into the refrigeration circuit, thus making it available for potential heat pump applications for energy-efficient heating of the interior and / or the energy storage system.However, this invention focuses on the heat-absorbing side, while there are many design possibilities for the interconnection of the refrigeration circuit on the heat-emitting side.

[0009] According to a further embodiment of the invention, a first actuating element is a three-way valve, of which a first inlet can be connected to an outlet of the heat source, a second inlet to at least one outlet of the chiller and an outlet to an inlet of at least one of the ambient air coolers.

[0010] According to a further embodiment of the invention, a second actuating element is a three-way valve, of which a first inlet can be connected to an outlet of at least one of the ambient air coolers, a second inlet to at least one outlet of the heat source and an outlet to an inlet of the chiller.

[0011] According to the invention, in the first operation and / or in the second operation, the actuators additionally form a secondary cooling circuit through which the heat source and at least one of the ambient air coolers can flow.

[0012] According to a further embodiment of the invention, in the first operation an exchange of coolant between the main cooling circuit and the secondary cooling circuit is essentially prevented.

[0013] According to the invention, in the second operation, the main cooling circuit flows into the secondary cooling circuit downstream of the energy storage device, so that the main cooling circuit and the secondary cooling circuit overlap section by section.

[0014] According to a further embodiment of the invention, a check valve is provided downstream of the energy storage device.

[0015] According to a further embodiment of the invention, the heat source is at least one element from the group comprising: an electronic component, in particular a power electronic component, an electric machine, in particular an electric motor and / or a generator, an internal combustion engine, at least one auxiliary unit of the internal combustion engine, a coolant-air heat exchanger of a rear ventilation system (which may, for example, be arranged in the rear ventilation system for energy recovery from interior air) and an electric heater.

[0016] Furthermore, the present invention provides a motor vehicle with such a cooling system.

[0017] A preferred embodiment of the present invention is described below with reference to the accompanying drawings. These drawings illustrate the following: Fig. Figure 1 shows a cooling system according to the invention in an exemplary embodiment; Fig. 2 represents an initial operation of the cooling system Fig. 1 dar; Fig. 3 represents a second operation of the cooling system Fig. 1 dar; and Fig. 4 represents a third operation of the cooling system Fig. 1 dar.

[0018] Fig. Figure 1 shows a cooling system 1 according to the invention in an exemplary embodiment. The cooling system 1 is particularly suitable for a motor vehicle that is driven partially or fully electrically, especially for a hybrid or electric vehicle. The cooling system 1 comprises a first ambient air cooler 2a and a second ambient air cooler 2b, each with an electric fan 3. Furthermore, the cooling system 1 has a first coolant pump 4, a heat source 5, a chiller 6, and an electrical energy storage device 7.The heat source 5 can be one or more elements from the following group, which includes: an electronic component (for example, a power electronics component), an electric machine (for example, an electric motor and / or a generator), an internal combustion engine, at least one auxiliary component of the internal combustion engine, a coolant-to-air heat exchanger of a rear vent (which, for example, may be arranged in the rear vent for energy recovery from interior air), and an electric heater. The chiller 6 is a refrigerant-to-coolant heat exchanger that can transfer thermal energy between the refrigerant and the coolant, which are fluidically separated. Reference numeral 8 indicates a refrigeration circuit that flows through the chiller 6, wherein the refrigeration circuit 8 is fluidically separated from a main cooling circuit that also flows through the chiller 6.The energy storage unit 7 is an electrical energy storage unit used to power the motor vehicle, in particular comprising lithium-ion cells.

[0019] Furthermore, the cooling system 1 comprises a second coolant pump 9, a check valve 10, a first actuator 11, and a second actuator 12. The first actuator 11 and the second actuator 12 are each three-way valves. In particular, in the present embodiment, the three-way valves are installed such that they form two inlets and one outlet.

[0020] The following describes the interconnection of the aforementioned components, where the term "connected" refers to a fluidically conductive line, for example in the form of hoses or pipes, of the cooling system. An outlet of the first ambient air cooler 2a is connected to an inlet of the first coolant pump 4. Downstream of the outlet of the first coolant pump, a coolant line branches, with one coolant line leading to an inlet of the second ambient air cooler 2b and the other coolant line leading to an inlet of the heat source 5. The outlet of the heat source 5 is connected to a first inlet 13 of the first actuator 11. An outlet 14 of the first actuator is in turn connected to the inlet of the first ambient air cooler 2a. An outlet of the second ambient air cooler 2b is connected to a first inlet 15 of the second actuator 12.Reference symbol S1 designates a first temperature measuring point downstream of the second ambient air cooler 2b and upstream of the second actuator 12. A second inlet 16 of the second actuator 12 is connected at a connection point 17 to the line leading from the outlet of the heat source 5 to the first inlet 13 of the first actuator 11. An outlet 18 of the second actuator 12 is connected to the inlet of the chiller 6. The outlet of the chiller 6 branches off, on the one hand, to a second inlet 19 of the first actuator 11 and, on the other hand, to an inlet of the second coolant pump 9. The outlet of the second coolant pump 9 leads to an inlet of the energy storage unit 7, and an outlet of the energy storage unit 7 leads to a connection point 20 where a line coming from the outlet of the energy storage unit 7 is joined with the line leading from the second inlet 16 of the second actuator 12 to the connection point 17.A check valve 10 is provided in the line leading from the outlet of the energy storage unit 7 to the connection point 20. This check valve is configured to allow flow only from the outlet of the energy storage unit 7 to the connection point 20. A temperature measuring point S2 is provided between an inlet of the check valve 10 and the outlet of the energy storage unit 7. Temperature measuring points S1 and S2 provide the temperature of the coolant flowing at this point via temperature sensors. An expansion tank, designated 21, is integrated into the cooling system 1 such that an outlet of the expansion tank 21 opens into the line leading from the outlet of the first ambient air cooler 2a to the inlet of the first coolant pump 4. The inlets of the expansion tank 21 are each connected to the ambient air coolers 2a and 2b, respectively.The ambient air coolers 2a, 2b can be configured as two separate ambient air coolers, as shown, or as a single ambient air cooler. Alternatively, they can be structurally designed as a single ambient air cooler that is internally subdivided.

[0021] As an alternative to the above-described setup, the coolant pump 9 can also be arranged in the line between the energy storage unit 7 and the connection point 20.

[0022] Alternatively, the temperature measuring point S2 can also be arranged between the outlet of the check valve 10 and the connection point 20 as described above.

[0023] Three different operating states of the cooling system 1 are described below. In each operating state, lines through which coolant flows are shown as solid lines, and lines without coolant or with stagnant coolant are shown as dotted lines. The two lines at the inlet of the expansion tank 21 are always shown as dashed lines, regardless of the operating state or the flow rate.

[0024] Fig. 2 represents a first operation. In this first operation, a main cooling circuit is formed in which the coolant flows, in the following order, through the chiller 6, the second coolant pump 9, the energy storage unit 7, the check valve 10 and the second actuator 12, in order to then be returned to the chiller 6.

[0025] Furthermore, in the first operating mode, a secondary cooling circuit is established in which, in the following order, the coolant flows through the first ambient air cooler 2a, the first coolant pump 4, and the heat source 5. From the heat source 5, the secondary cooling circuit leads via the first actuator 11 back to the inlet of the first ambient air cooler 2a.

[0026] To establish this main cooling circuit and this secondary cooling circuit, the first input 15 of the second actuator 12 is blocked and the second input 16 is open, so that the second actuator 12 is connected from the second input 16 to the output 18. Furthermore, the first actuator 11 is connected such that the second input 19 is blocked and the first input 13 is open, so that the first actuator 11 is connected from the first input 13 to the output 14.

[0027] Due to the blockage of the second inlet 19 of the first actuator 11, no coolant flow occurs in the dotted line section 22, so no coolant can flow out of the main cooling circuit. Since no coolant flows out of the main cooling circuit, no coolant can flow from the auxiliary cooling circuit into the main cooling circuit via the dotted line section 23. Consequently, there is essentially no coolant exchange between the main cooling circuit and the auxiliary cooling circuit (apart, of course, from minimal exchange within line 23 itself).

[0028] This first operation is selected in particular, for example by an air conditioning control system, if a coolant temperature at temperature measuring point S2 is lower than a coolant temperature at temperature measuring point S1, or if waste heat from the energy storage unit 7 is to be used for a heat pump application, i.e., if the waste heat from the energy storage unit 7 is to be fed into the refrigeration circuit 8 via the chiller 6 in order to use the refrigeration circuit 8 for heating purposes.

[0029] If there is neither a cooling demand for the energy storage unit 7 nor a heat pump demand, then the main cooling circuit can also be deactivated by switching off the second coolant pump 9. In such a case, only the secondary cooling circuit would be active and not the main cooling circuit; that is, coolant would flow in the secondary cooling circuit while the coolant in the main cooling circuit remains stationary.

[0030] Fig. 3 represents a second operating mode. In this second mode, a secondary cooling circuit is established in which, in the following order, the coolant flows through the first ambient air cooler 2a, the first coolant pump 4, and the heat source 5. From the heat source 5, the secondary cooling circuit leads via the first actuator 11 back to the inlet of the first ambient air cooler 2a.

[0031] Furthermore, in this second operation, a main cooling circuit is formed in which the coolant branches off downstream of the first coolant pump 4 and upstream of the heat source 5 at a connection point 24 and flows through the second ambient air cooler 2b, the second actuator 12, the chiller 6, the second coolant pump 9, the energy storage unit 7, and the check valve 10 in the following sequence, in order to flow back into the secondary cooling circuit at connection point 17. The main cooling circuit and the secondary cooling circuit overlap between connection point 17 and connection point 24.

[0032] In order for this secondary cooling circuit and this main cooling circuit to be established in the second operating mode, the first input 15 of the second actuator 12 is open and the second input 16 is blocked, so that the second actuator 12 is connected from the first input 15 to the output 18. Furthermore, the first actuator 11 is connected such that the second input 19 is blocked and the first input 13 is open, so that the first actuator 11 is connected from the first input 13 to the output 14.

[0033] In this second operating mode, the ambient air coolers 2a and 2b, the chiller 6, and the energy storage unit 7 are arranged in series. The ambient air coolers 2a and 2b thus ensure the lowest possible temperature level in the main cooling circuit, which is then further reduced by the chiller 6, which receives additional cooling from the refrigeration circuit 8. This second operating mode is advantageous when the coolant temperature at temperature measuring point S2 is higher than the coolant temperature at temperature measuring point S1 and when a heat pump application is not intended. When the chiller 6 is active, it provides additional subcooling of the coolant supplied by the second ambient air cooler 2b. This enables particularly powerful and energy-efficient cooling of the energy storage unit 7.In this second operation, it is also possible that, depending on the cooling capacity requirement, the chiller 6 is indeed flowed through, but is shut off on the refrigerant side to increase energy efficiency.

[0034] Fig. 4 represents a third operation. In the third operation, a main cooling circuit is formed in which, in the following order, the coolant flows through the first ambient air cooler 2a, the first coolant pump 4, the heat source 5, the second actuator 12, the chiller 6 and the first actuator 11, in order to be led from the first actuator 11 back to the first ambient air cooler 2a.

[0035] To form this main cooling circuit, the second actuator 12 is connected such that the first input 15 is blocked and the second input 16 is open, so that the second actuator 12 is connected from the second input 16 to the output 18. The first actuator 11 is connected such that the second input 19 is open and the first input 13 is blocked, so that the first actuator 11 is connected from the second input 19 to the output 14.

[0036] In this third operating mode, the first ambient air cooler 2a, the heat source 5, and the chiller 6 are connected in series. The coolant pump 9 is inactive, so there is no flow through the energy storage unit 7. In this third operating mode, heat or waste heat from the heat source 5 is transported to the chiller 6 and can be used for a heat pump application. This means that the heat or waste heat from the heat source 5 can be transferred via the chiller 6 into the refrigeration circuit 8 and thus used for heating purposes via the refrigeration circuit 8. This third operating mode is advantageous when there is no cooling requirement for the energy storage unit 7 and the heat from the heat source 5 or the ambient heat (which is absorbed by the ambient air cooler, as described above) is to be used for a heat pump application.

[0037] While the invention has been illustrated and described in detail in the drawings and the preceding description, this illustration and description is to be understood as illustrative or exemplary and not as limiting, and it is not intended to limit the invention to the disclosed embodiment. The mere fact that certain features are mentioned in various dependent claims is not intended to imply that a combination of these features could not also be advantageously used.

Claims

[1] Cooling system (1) for a motor vehicle, with an electrical energy storage device (7) for powering the motor vehicle; a chiller (6) which is connected to a refrigeration circuit (8) and is fluidically separated from it by a main cooling circuit, in order to transfer heat energy between the refrigeration circuit (8) and the main cooling circuit; one or more actuators (11, 12); at least one heat source (5), and one or more ambient air coolers (2a, 2b), wherein In a first operation, the actuators (11, 12) configure the main cooling circuit in such a way that the chiller (6), the energy storage (7) and none of the ambient air coolers (2a, 2b) can be permeated by it; In a second operation, the actuators (11, 12) configure the main cooling circuit such that the chiller (6), the energy storage unit (7) and at least one of the ambient air coolers (2a, 2b) can be permeated by this circuit, and In a third operation, the actuators (11, 12) configure the main cooling circuit such that the chiller (6), at least one of the ambient air coolers (2a, 2b) and the heat source (5) can flow through it, wherein in the first operation and / or in the second operation the actuators (11, 12) additionally configure a secondary cooling circuit through which the heat source (5) and at least one of the ambient air coolers (2a) can flow, wherein in the second operation the main cooling circuit opens into the secondary cooling circuit downstream of the energy storage (7), so that the main cooling circuit and the secondary cooling circuit overlap section by section. [2] Cooling system (1) according to claim 1, wherein in the third operation the chiller (6) is arranged downstream of the heat source (5) and upstream of the at least one ambient air cooler (2a, 2b). [3] Cooling system (1) according to one of the preceding claims, wherein a first actuating element (11) is a three-way valve, of which a first inlet (13) can be connected to an outlet of the heat source (5), a second inlet (19) to at least an outlet of the chiller (6) and an outlet (14) to an inlet of at least one of the ambient air coolers (2a). [4] Cooling system (1) according to one of the preceding claims, wherein a second actuating element (12) is a three-way valve, of which a first inlet (15) can be connected to an outlet of at least one of the ambient air coolers (2b), a second inlet (16) to at least one outlet of the heat source (5) and an outlet (18) to an inlet of the chiller (6). [5] Cooling system (1) according to one of the preceding claims, wherein in the first operation an exchange of coolant between the main cooling circuit and the secondary cooling circuit is substantially prevented. [6] Cooling system (1) according to one of the preceding claims, wherein a check valve (10) is provided downstream of the energy storage device (7). [7] Cooling system (1) according to one of the preceding claims, wherein the heat source (5) is at least one element from the group comprising: an electronic component, in particular a power electronic component, an electric machine, in particular an electric motor and / or a generator, an internal combustion engine, at least one auxiliary unit of the internal combustion engine, a coolant-air heat exchanger of a rear vent and an electric heater. [8] Motor vehicle with a cooling system (1) according to any one of the preceding claims.

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