Method for operating a cooling system for a motor vehicle, cooling system and motor vehicle

Abstract

The invention relates to a method for operating a cooling system (1) for a motor vehicle (2) comprising at least one circuit (3) through which a refrigerant or coolant flows, with a first heat exchanger and a second heat exchanger connected to each other by a line (8), and an air duct system (10) with an external space (11) in which the first heat exchanger (4) is arranged, and an air duct element (12) through which an airflow (9) in the external space (11) can be adjusted, wherein the cooling system (1) can be operated in a first operating mode as a heat pump and in a second operating mode as an air conditioner, wherein, depending on at least one state value and on the operating mode, before and / or after the cooling system (1) is operated in the latter mode, an air exchange takes place in the external space (11) through the air duct element (12), so that icing of the first heat exchanger can be avoided predictively.Furthermore, the invention relates to a cooling system (1) and a motor vehicle (2).

Description

[0001] The invention relates to a method for operating a cooling system of a motor vehicle according to claim 1. Furthermore, the invention relates to a corresponding cooling system and a motor vehicle comprising a cooling system according to claims 9 and 11.

[0002] Motor vehicles often have a cooling system that can be used as an ambient heat pump. To increase the operating range or heating capacity of an ambient heat pump, it is advantageous, or even necessary, for the dew point to be reached on the cooling unit. This dew point drop, when sufficient moisture is present, leads to ice formation on the radiator or evaporator. This icing prevents heat transfer into the cooling system and thus reduces the heating capacity of the heat pump. Additionally, the ice formation puts mechanical stress on the radiator.

[0003] Therefore, in current vehicle generations, it is often ensured that the dew point on the cooling package or on the evaporator is not undercut during heat pump operation of a cooling system.

[0004] Furthermore, DE 10 2011 051 285 A1 discloses a method for icing prevention control for evaporators of heat pumps in air conditioning systems in vehicles.

[0005] Furthermore, DE 10 2012 102 041 A1 shows a method for icing prevention control for heat pump evaporators.

[0006] The object of the present invention is therefore to provide a method for operating a cooling system for a motor vehicle, as well as a cooling system and a motor vehicle, by which a heat exchanger, for example an evaporator, of the cooling system or of a cooling package, which in particular comprises an air duct system and the heat exchanger, can be advantageously protected from icing.

[0007] This problem is solved according to the invention by the subject matter of the independent claims. Advantageous embodiments and further developments are the subject matter of the dependent claims, the description, and the drawings.

[0008] A first aspect of the invention relates to a method for operating a cooling system for a motor vehicle, which is particularly designed as a passenger car and / or truck. The cooling system, which is operated by means of the method according to the invention, comprises at least one circuit through which a coolant or refrigerant flows, in particular a refrigeration circuit, with a first heat exchanger, for example an evaporator, and a second heat exchanger, for example a condenser, which are connected to each other by or via a line. For example, the cooling system thus comprises the evaporator, a compressor, in particular for compressing the refrigerant, the condenser, which functions as the second heat exchanger, in particular in or for the interior of the motor vehicle, and a throttle, which may in particular be designed as a controllable expansion valve.In this arrangement, the components—evaporator, compressor, condenser, and expansion valve—are connected to each other by means of a line designed as a refrigerant line.

[0009] Furthermore, the cooling system comprises an air distribution system with an outdoor chamber in which the first heat exchanger is located, and an air guide element through which an airflow in the outdoor chamber can be adjusted, in particular regulated and / or controlled. The cooling system, and in particular the circuit, can be operated in a first operating mode as a heat pump (or at least as a component of a heat pump) and in a second operating mode as an air conditioner (or at least as a component of an air conditioner).

[0010] In order to keep the cooling system, or in particular its first heat exchanger, particularly ice-free, the inventive method involves an air exchange in the outside space, i.e. the space in which the first heat exchanger is located, through the air guide element, depending on at least one state value and the operating mode, before and / or after the cooling system is operated in the latter, i.e. the selected operating mode, so that icing of the first heat exchanger and in particular evaporator icing can be avoided predictively, or predictive radiator icing protection can be achieved by means of blowing.

[0011] The cooling system thus comprises, in particular, a compression refrigeration unit as its circuit, which can be used for both cooling and heating the interior space adjacent to the condenser. Alternatively, the cooling system could, for example, include a "classic" automotive radiator as the first heat exchanger, connected via a coolant line to the second heat exchanger. This second heat exchanger can then function as an evaporator or chiller of a second circuit, which in particular constitutes a refrigerant circuit. The cooling system could also thus have a first circuit, for example, a coolant circuit, and a second circuit, in particular a refrigerant circuit, connected to it via the second heat exchanger.

[0012] The air guide element is, for example, a fan or ventilator, which is often combined with adjustable flaps that may be arranged in a duct element of the air guide system. The first heat exchanger, together with the air guide system, can form a cooling package. The exterior space differs from the interior of the vehicle and is located within the vehicle's outer skin, particularly in the front area, and is thus, for example, part of the vehicle's engine compartment. The evaporator is therefore designed as the vehicle's radiator. In operation as a heat pump, the vehicle's interior can be heated, with the evaporator using ambient air, or outside air, as the source for evaporating the liquid refrigerant. This ambient air is located in the vicinity of the vehicle and passes through the air guide system onto the evaporator.

[0013] In other words, the inventive method presents a method for delaying the icing of moisture on the cooling pack of a heat pump, wherein an airflow removes the moisture from the cooling pack, and wherein the airflow can be controlled by a control device, the control taking into account the possibility of ice formation via a state value such as temperature, humidity, and / or dew point. In particular, during this operating mode, heat from the environment is transferred via the fan and the cooling pack into the coolant or refrigerant and made available to a chiller or the condenser as a source for the heat pump.In this process, the cooling unit temperature can be deliberately lowered below the ambient temperature to absorb heat, whereby the dew point can also be undercut, which could lead to ice formation or icing on the evaporator in heat pump operation when subcooling below ambient temperature.

[0014] However, by blowing out air from the outside before the actual operating mode, the potential amount of icing water can be reduced, thus preventing icing altogether. This allows for the advantageous preservation of heat transfer to the refrigerant and reduces the moisture load on the cooling package. The advantage of the method according to the invention is that it delays icing if moisture is present in the cooling package, as this moisture can be reduced. The method provides a control device that, before the relevant operating conditions, removes the base moisture from the cooling package by means of, for example, a fan and air damper.

[0015] In an advantageous embodiment of the invention, the at least one state value describes, or is, an outside temperature, in particular a temperature of the exterior of the motor vehicle and / or an ambient temperature and / or a coolant temperature and / or a refrigerant temperature, in particular at the evaporator of the circuit, and / or a dew point, i.e., the temperature at which moisture contained in the air condenses, and / or a humidity level, which describes the weight fraction of gaseous water vapor in the air. In other words, the state value describes an environmental variable, in particular various temperatures, in combination with humidity, and thus the probability of how likely and / or how large a temperature change at the evaporator might be during operation.This offers the advantage that the process can be initiated in a particularly needs-based manner, thus avoiding unnecessary blowing out or clearing of the outside space.

[0016] In a further advantageous embodiment of the invention, the air exchange, in particular the blowing out or exhausting, is initiated by means of a switch-on delay and / or a switch-off delay of the cooling system. In other words, when one of the operating modes, in particular the first operating mode, is selected, for example by user input, it is checked whether an air exchange is necessary and, if so, the switching on of the actual operating mode is delayed. Additionally or alternatively, the cooling system can briefly perform the air exchange after the operating mode has been switched off by a fan, thus effectively creating a switch-off delay. This offers the advantage that air exchange can be carried out particularly efficiently before or after the actual operating mode.

[0017] In a further advantageous embodiment of the invention, the air exchange takes place depending on the first operating mode, wherein, in particular, the temperature of the first heat exchanger is below the ambient temperature in the first operating mode. In other words, the heat pump operation of the circuit is carried out as a particularly advantageous operating mode for the method. To enable a particularly high heating output, the temperature of the first heat exchanger can be below the ambient temperature, so that condensation of humidity from the surroundings or outside air would be promoted there, which can be particularly advantageously avoided by the air exchange.

[0018] In a further advantageous embodiment of the invention, a rain sensor and / or a wiper speed are used to determine at least one state value, particularly when this value is humidity, especially relative humidity. In other words, a rain sensor is used to determine how humid an environment is, so that the method can be initiated accordingly. Additionally or alternatively, a conclusion about the possible humidity or amount of rain in the ambient air is drawn based on a wiper speed, especially of the windshield wipers, which is specified by the user, thus allowing the wiper speed to be used to determine the state value.This offers the advantage that the process can be carried out particularly efficiently, since, for example, no extra sensors need to be used to detect the status value, as the derivation is done via the wiper speed.

[0019] In a further advantageous embodiment of the invention, a camera with image recognition is used to determine at least one state value. In other words, a camera already present in the motor vehicle, for example used for a driver assistance system, is used to take pictures which are then analyzed using image recognition in order to determine, for example, the amount of rainfall or the humidity of the ambient air.

[0020] Image recognition can, for example, be based on machine learning methods and, in particular, include machine vision. This offers the advantage that the process can be carried out particularly efficiently, since, in particular, special sensors for capturing at least one state value can be dispensed with.

[0021] In a further advantageous embodiment of the invention, the determination of at least one state value is carried out using weather data. In other words, based on data provided by a weather service or weather station, current humidity and / or temperature, or at least one state value, is retrieved or at least estimated, particularly in the current standard. The weather data can be retrieved, for example, via a communication device such as a modem of an infotainment system. This offers the advantage that sensors determining the at least one state value can be completely dispensed with in the vehicle, or the method can still be carried out even if these sensors fail, since external information sources can be used.

[0022] In a further advantageous embodiment of the invention, the air exchange, in particular the blowing out or expelling, is additionally carried out depending on a driving condition of the vehicle. In other words, in addition to the at least one state value and the type of operating mode, it is carried out depending on a state that describes the driving of the vehicle. The driving condition is, in particular, a speed. Furthermore, it can, for example, be acceleration or deceleration and / or driving straight ahead. Thus, it may be the case that, for example, at speeds of 150 km / h, when starting, for example, the first operating mode, the air exchange can be carried out almost automatically due to the airflow from driving, without switching on an additional fan.However, at 0 km / h, for example, the fan, which is clearly audible if it acts as the air guide element, can be operated at 50%, so the air exchange may take a little longer, but noise pollution or volume for a user of the vehicle can be reduced.

[0023] A second aspect of the invention relates to a cooling system for a motor vehicle comprising at least one circuit through which a refrigerant or coolant flows, with a first heat exchanger and a second heat exchanger connected to each other by a line through which the refrigerant or coolant can flow in the circuit. Furthermore, the cooling system according to the invention comprises an air duct system with an external chamber in which the first heat exchanger is arranged and an air guide element through which an airflow in the external chamber can be adjusted. The cooling system, and in particular its circuit, can be operated in a first operating mode as a heat pump and in a second operating mode as an air conditioner. The cooling system according to the invention can be operated by means of a method according to the first aspect of the invention.

[0024] Advantages, advantageous embodiments and further developments of the first aspect of the invention are to be regarded as advantages, advantageous embodiments and further developments of the second aspect of the invention and vice versa.

[0025] In an advantageous embodiment of the invention, the first heat exchanger is configured as an evaporator and the second heat exchanger as a condenser. In the circuit, which is particularly designed as a refrigeration circuit, the refrigerant line connects the evaporator, a compressor, the condenser, and an expansion valve in that order. In other words, the cooling system comprises a refrigerant circuit. This offers the advantage that the first operating mode – heat pump – and the second operating mode – air conditioning – can be implemented particularly advantageously.

[0026] A third aspect of the invention relates to a motor vehicle with a cooling system according to the second aspect of the invention and / or is configured to carry out a method for operating a cooling system according to the first aspect of the invention.

[0027] Advantages, advantageous embodiments and further developments of the third aspect of the invention are to be regarded as advantages, advantageous embodiments and further developments of both the first and second aspects of the invention and vice versa.

[0028] Further features of the invention will become apparent from the claims, the figures, and the description of the figures. The features and combinations of features mentioned above in the description, as well as the features and combinations of features mentioned below in the description of the figures and / or shown in the figures alone, are not only usable in the combinations specified, but also in other combinations or on their own.

[0029] The invention will now be explained in more detail with reference to a preferred embodiment and the drawings. The drawings show: Fig. 1 a schematic side view of the front of a motor vehicle with a cooling system; Fig. 2 a schematic circuit diagram of a first embodiment of the cooling system according to Fig. 1; Fig. 3 a schematic circuit diagram of a second embodiment of the cooling system according to Fig. 1; and Fig. 4 a schematic circuit diagram of a third embodiment of the cooling system according to Fig. 1.

[0030] Fig. Figure 1 shows a schematic side view of the front of a motor vehicle 2, which has a cooling system 1. The cooling system 1 comprises at least one circuit 3 through which a refrigerant or coolant flows, with a first heat exchanger 4 and a second heat exchanger 6, which are connected to each other by a line 8 designed as a coolant line, wherein the cooling system 1 can be operated in a first operating mode as a heat pump and in a second operating mode as an air conditioning system.

[0031] Furthermore, the cooling system 1, and thus the motor vehicle 2, comprises an air duct system 10 with an outer chamber 11 in which the first heat exchanger 4 is arranged. The air duct system 10 includes an air guide element 12, which in the exemplary embodiment is designed as a fan, through which an airflow 9 in the outer chamber 11 can be adjusted. Ventilation flaps 13 can also be assigned to the air guide element 12 or the air duct system 10, the opening and closing of which can also influence the airflow 9. The air duct system 10 can form a so-called cooling package 16 together with the evaporator 4.

[0032] In order to avoid icing or freezing of the first heat exchanger 4, particularly in the first operating mode, i.e. in the operation of the cooling system 1 and especially of the circuit 3 as a heat pump, in a method presented here, depending on at least one state value and depending on the operating mode, an air exchange in the outside space 11 is carried out or takes place by the air guide element 12, depending on at least one state value and depending on the operating mode, before and / or after the cooling system 1 is operated with the latter.

[0033] Fig. Figure 2 shows a first embodiment of the cooling system 1 of the motor vehicle 2. The circuit 3 is thus designed as a cooling circuit and is thermally connected to a refrigeration circuit 18 via the second heat exchanger 6. The second heat exchanger 6 is designed as a chiller, which functions as an evaporator for the refrigerant and through which heat exchange with the refrigerant is possible. The first heat exchanger 4 is designed, in particular, as a vehicle radiator and, in one operating mode, heats the subcooled refrigerant coming from the chiller via the surrounding environment. The chiller can, in turn, provide the heat from the refrigerant to a further heat exchanger 19, in particular a condenser. The refrigeration circuit 18 can be connected to a further circuit 20 via the further heat exchanger.

[0034] Fig. Figure 3 shows a second embodiment of the cooling system 1 of the motor vehicle 2, wherein the coolant circuit 3 is connected in parallel with another circuit, the refrigeration circuit 18. The cooling package 16 thus includes the first heat exchanger 4 for each of the two circuits 3 and 18, so that the method can be carried out for both circuit 3 and refrigeration circuit 18. Furthermore, an intercooler 21 can be provided in these embodiments.

[0035] A similar structure to the embodiment of Fig. 2 shows the embodiment of the Fig. 4. The second heat exchanger 6, designed as a chiller, can transfer heat from the coolant to the interior of the vehicle 2, for example by means of an evaporator 17. The circuit 3 can thus be operated at least as a component of a heat pump, which therefore represents the first operating mode.

[0036] Circuit 3, particularly in combination with refrigeration circuit 18, is thus a circuit that can be operated as a heat pump and as an air conditioner. The second heat exchanger 6, or chiller, can function as an air conditioner condenser. A throttle valve 7, which is designed as a controllable expansion valve for opening and closing, and a compressor 5, which is a mechanical refrigerant compressor, together with the evaporator 17, then form refrigeration circuit 18.

[0037] The method presented here serves to control the purging of the cooler or first heat exchanger 4 before the relevant operating mode. It is therefore a control device, which was provided in particular by a control unit 14, which can be used to carry out the method.

[0038] The at least one state value is in particular an outside temperature, a coolant temperature, in particular an evaporator, a dew point and / or a humidity or humidity load of the environment and thus describes in particular an environmental condition currently prevailing at the motor vehicle 2.

[0039] To enable air exchange before and / or after the cooling system 1 is operated in operating mode, this can be initiated by means of a switch-on delay and / or a switch-off delay of the cooling system 1.

[0040] The air exchange occurs particularly depending on the first operating mode, which is the operating mode on which the air exchange depends. In this first operating mode, the first heat exchanger 4 is operated below the ambient temperature or outside temperature.

[0041] To determine at least one state value, a rain sensor and, additionally or alternatively, for example the wiper speed of a windshield wiper can be used, especially if one of the state values ​​is humidity or moisture load.

[0042] Furthermore, at least one condition value, particularly when it concerns humidity or moisture exposure, can be determined using a camera equipped with computer vision or other image recognition technology, which can thus, for example, detect rain on the windshield. It is advantageous that the vehicle 2 can be designed with a minimal number of components, since, for example, no additional sensors are needed to determine the at least one condition value if the rain sensor, wiper speed sensor, or camera, which are already present in the vehicle 2, are used.

[0043] Furthermore, it is possible to use weather data, which can be retrieved, for example, via a communication device such as a wireless modem of an infotainment system of the vehicle 2, to determine at least one status value completely independently of the vehicle 2's own sensors.

[0044] The air exchange is particularly advantageous when carried out depending on a driving condition of the motor vehicle 2, such as acceleration, deceleration and especially speed.

[0045] Fig. Figure 4 shows a schematic circuit diagram for a third embodiment of the cooling system 1, wherein in addition to the circuits 3 and 18 further switchable circuits 20 are available, which serve, for example, to cool the high-voltage storage device 15.

[0046] Cooling system 1 primarily serves to transfer heat from the environment via the fan and cooling pack into the coolant or refrigerant and, for example, to the chiller or the second heat exchanger 6 as a source for the heat pump. In particular, the cooler inlet temperatures are deliberately lowered below the ambient temperature to maximize heat absorption. This can cause the dew point to be undershot, which would lead to ice formation on the cooler. Therefore, icing on the first heat exchanger 4 is very likely during heat pump operation when the temperature is sub-zero.

[0047] To avoid or at least reduce icing in all embodiments, the aforementioned air exchange is carried out so that a specific amount of water located in the outer chamber 11 can be blown out. This is in Fig.The airflow is indicated by the arrows in section 1, which represent the airflow in section 9. Since this method minimizes or delays icing, it also offers the advantage of maintaining heat transfer to the coolant or refrigerant. An ice layer on the first heat exchanger 4 would provide excellent insulation, resulting in reduced heat exchange and thus a decrease in the heat pump's output. Furthermore, by minimizing icing, the stress on the first heat exchanger 4 is kept to a minimum.

[0048] The method, or rather the control device formed by it, particularly due to the control unit 14, enables the cooling system to be vented into its surroundings before the relevant heat pump operating mode. Furthermore, the possibility of ice formation was taken into account based on temperature, humidity, and dew point.

[0049] The system requirements are adapted and implemented, in particular, via a switch-on and switch-off delay. The blow-off function can be activated based on vehicle speed. A rain sensor or the windshield wiper speed can be used to detect potential moisture levels. Furthermore, a camera-based moisture assessment using image recognition via the vehicle's systems is demonstrated. The system can also incorporate current weather data.

[0050] Through the process, the cooling system 1 and the motor vehicle 2, a predictive radiator icing protection by means of blowing is thus made possible. Reference symbol list 1 Cooling system 2 motor vehicles 3 cycle 4 first heat exchanger 5 Compressor 6 second heat exchanger 7 Throttle 8 Line 9 Airflow 10 Air duct system 11 Outdoor area 12 Air guide element 13 Ventilation flap 14 Control unit 15 high-voltage storage units 16 Cooling package 17 evaporators 18 Refrigeration cycle 19 additional heat exchangers 20 further cycles 21 Intercoolers QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2011 051 285 A1

[0004] DE 10 2012 102 041 A1

[0005]

Claims

[1] Method for operating a cooling system (1) for a motor vehicle (2) comprising at least one circuit (3) through which a refrigerant or coolant flows, with a first heat exchanger (4) and a second heat exchanger (6) which are connected to each other by a line (8), and an air duct system (10) with an outside space (11) in which the first heat exchanger (4) is arranged, and an air duct element (12) through which an air flow (9) in the outside space (11) can be adjusted, wherein the cooling system (1) can be operated in a first operating mode as a heat pump and in a second operating mode as an air conditioner, characterized by , that depending on at least one state value and the operating mode, before and / or after the cooling system (1) is operated with the latter, an air exchange takes place in the outside space (11) through the air guide element (12), so that icing of the first heat exchanger (4) can be avoided predictively. [2] Method according to claim 1, characterized by , that at least one state value describes an outside temperature, an ambient temperature, a coolant temperature, a refrigerant temperature, a dew point and / or a humidity level. [3] Method according to claim 1 or 2, characterized by , that the air exchange is initiated by means of a switch-on delay and / or a switch-off delay of the cooling system (1). [4] Method according to any one of the preceding claims, characterized by , that the air exchange takes place depending on the first operating mode and in particular in the first operating mode a temperature of the first heat exchanger (4) is below the ambient temperature. [5] Method according to any one of the preceding claims, characterized by , that a rain sensor and / or wiper speed is used to determine at least one state value. [6] Method according to any one of the preceding claims, characterized by , that a camera with image recognition is used to determine at least one state value. [7] Method according to any one of the preceding claims, characterized by that the determination of at least one state value is carried out using weather data. [8] Method according to any one of the preceding claims, characterized by , that the air exchange is additionally carried out depending on a driving condition of the motor vehicle (2). [9] Cooling system (1) for a motor vehicle (2) comprising at least one circuit (3) through which a refrigerant or coolant flows, with a first heat exchanger and a second heat exchanger which are connected to each other by a line (8), and an air duct system (10) with an outside space (11) in which the first heat exchanger (4) is arranged, and an air duct element (12) through which an air flow (9) in the outside space (11) can be adjusted, and the cooling system (1) can be operated in a first operating mode as a heat pump and in a second operating mode as an air conditioner and which can be operated by means of a method according to one of the preceding claims. [10] Cooling system (1) according to claim 9, characterized by, that the first heat exchanger (4) is designed as an evaporator and the second heat exchanger (6) as a condenser, and in the circuit (3) the line (8) as refrigerant line connects the evaporator (4), a compressor (5), the condenser (6) and a throttle (7) which connects them in the order mentioned. [11] Motor vehicle (2) with a cooling system (1) according to claim 9 or 10 and / or equipped to carry out a method for operating a cooling system (2) according to any one of claims 1 to 8.

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