Splash water-related regulation of heat pump

Abstract

In order to provide a method for operating a heat pump (10), in particular in a motor vehicle (100), having an ambient heat exchanger (20) and an interior heat exchanger (40), which method avoids an acceleration of icing of the evaporator of the heat pump due to the influence of splashing water, it is proposed that the presence of splashing water (S) in the surroundings (U) of the ambient heat exchanger (20) is detected, wherein, when the presence of splash water (S) is detected, a heat pump (10) for heating the interior heat exchanger (40) is operated at an evaporation temperature in the ambient heat exchanger (20), which is higher than the freezing temperature of the splash water (S), or the passenger compartment (101) is directly or indirectly heated by means of the heat of at least one alternative heat source (80, 81).

Description

[0001] This application is a divisional application of the prior invention application with the invention name “Splash water-related regulation of heat pump”, the application date of February 20, 2021 and the application number of 202110193485.0. Technical Field

[0002] The invention relates to a method for operating a heat pump, in particular a heat pump in a motor vehicle, which has an ambient heat exchanger and an interior heat exchanger which are connected to one another via a refrigerant circuit. The invention also relates to a motor vehicle having a heat pump. Background Art

[0003] In electrically driven vehicles, heat pumps are often used to heat the passenger compartment. In this process, the heat required to heat the passenger compartment is taken from the vehicle surroundings and fed into the passenger compartment. In the process, a heat exchanger that is thermally coupled to the vehicle surroundings is cooled to such an extent that the dew point of the air in the vehicle surroundings is lowered and frost forms on the surface of the heat exchanger.

[0004] Due to the formation of frost, the surfaces of the heat exchanger are increasingly frozen and thus hinder the efficient operation of the heat pump. In order to allow air to flow through the heat exchanger again, a defrost cycle or defrost process is required, in which the frozen heat exchanger is heated. The ice then melts and air can flow through the heat exchanger again. However, such defrost cycles impair the efficiency and performance of the heat pump.

[0005] Especially for passenger cars, the ambient heat exchanger of the heat pump is arranged in the front engine compartment and is therefore susceptible to water spray and splash water. During the heating operation of the heat pump, the temperature of the ambient heat exchanger may drop below 0° C., so that splash water reaching the ambient heat exchanger may freeze.

[0006] Due to splashing water, the ambient heat exchanger may freeze faster than due to the influence of condensed air humidity. The freezing of the ambient heat exchanger is accelerated by splashing water, so the ambient heat exchanger needs to undergo a defrosting process more frequently, and the efficiency of the heat pump is reduced. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a method for preventing the acceleration of ice formation of a heat pump evaporator due to the influence of splash water. The technical problem is solved according to the present invention by a method for operating a heat pump, the heat pump is especially a heat pump in a motor vehicle, the heat pump has an ambient heat exchanger and an interior heat exchanger connected to each other via a refrigerant circulation circuit, wherein it is provided that the presence of splash water in the surroundings of the ambient heat exchanger is detected, wherein when the presence of splash water is detected, the heat pump for heating the interior heat exchanger is operated at an evaporation temperature in the ambient heat exchanger that is higher than the freezing temperature of the splash water, or the interior heat exchanger is directly or indirectly heated using heat from at least one alternative heat source. The technical problem is also solved according to the present invention by a motor vehicle, which has a heat pump for implementing the above-mentioned method.

[0008] According to one aspect of the invention, a method for operating a heat pump, in particular in a motor vehicle, is provided. The heat pump has an ambient heat exchanger and an interior heat exchanger, which are connected to one another via a refrigerant circuit. The interior heat exchanger and the ambient heat exchanger of the heat pump can also be designed as a first heat exchanger and a second heat exchanger. Depending on the operating state of the heat pump, one heat exchanger can function as a condenser and one heat exchanger can function as an evaporator.

[0009] According to the invention, the presence of splash water in the surroundings of the ambient heat exchanger is detected. The detection of splash water can be performed continuously or at regular time intervals when necessary, for example due to weather data.

[0010] When splash water is detected, the heat pump for heating the interior heat exchanger is operated at an evaporation temperature in the ambient heat exchanger above the freezing temperature of the splash water. Alternatively, heat from at least one alternative heat source is used instead of the ambient heat exchanger to directly or indirectly heat the vehicle interior.

[0011] The method can prevent the heat pump from operating under operating conditions that do not allow efficient heat pump operation. By detecting water spray, rain or splashing water, an increased risk of icing of the ambient heat exchanger can be detected and the regulation of the heat pump can be adjusted accordingly.

[0012] The detection of splash water and the regulation or control of the heat pump can be realized by a controller, which can be connected to the heat pump in a data transmission manner. Optionally, the controller can be connected to at least one sensor in a data transmission manner in order to receive operating parameters, such as the temperature of the ambient heat exchanger, the air temperature, the operating state of the heat pump, the speed of the refrigerant compressor, etc. In addition, the controller can be connected to at least one sensor for detecting splash water in a data transmission manner.

[0013] In the event of splash water, the heat pump can no longer be operated in an icing mode of the ambient heat exchanger or the external heat exchanger by the method described. This can be achieved technically particularly simply if the evaporation temperature in the ambient heat exchanger is selected such that the surface temperature of the ambient heat exchanger does not fall below the condensation temperature or freezing temperature of the splash water.

[0014] Alternatively, it is also possible to no longer use external air as a heat source, but to use an alternative heat source for heating. Here, the waste heat can be provided, for example, by a drive component or by an electric heater.

[0015] In one embodiment, the heat of at least one vehicle component, in particular a drive component, a traction battery and / or power electronics, as an alternative heat source is used to directly heat the vehicle interior. As a result, waste heat generated by a vehicle component, for example, can be used as a heat source. Preferably, the waste heat can be transported to the area to be heated by at least one fan. In the case of a vehicle-side heat pump, for example, the vehicle interior can be directly heated with the waste heat provided. The heat pump can thus be deactivated or operated at reduced power in order to prevent icing of the ambient heat exchanger. In this case, the vehicle component can also be an electric heater, which is used only to provide waste heat.

[0016] The heat pump is deactivated while the interior heat exchanger is directly heated using heat from at least one alternative heat source, whereby icing of the ambient heat exchanger can be reliably prevented.

[0017] According to a further embodiment, the heat of at least one vehicle component, in particular a drive component, a traction battery and / or power electronics, as an alternative heat source, is used for indirect heating of the vehicle interior by heating at least one traction component heat exchanger connectable to the refrigerant circuit. In contrast to the direct supply of heated air to the exemplary vehicle interior, the heat provided or the air heated due to power loss can also be used to heat a further ambient heat exchanger. Thus, the heat pump can continue to operate via the connected traction component heat exchanger. The traction component heat exchanger can be arranged in the region of one or more drive components of the vehicle. The traction component heat exchanger can in particular replace the ambient heat exchanger that is damaged by splash water or can be connected to the refrigerant circuit in addition or in parallel to the ambient heat exchanger. When the ambient heat exchanger and at least one traction component heat exchanger are operated in parallel, the refrigerant flow through the first ambient heat exchanger can be throttled so that the evaporation temperature of the refrigerant is greater than 0° C. in order to avoid icing of the first ambient heat exchanger.

[0018] The occurrence of splashing water can be detected by evaluating the measurement data of at least one sensor, whereby the occurrence of splashing water can be determined technically reliably. In this case, the occurrence of splashing water can be detected, for example, by optical monitoring of the surroundings or by detecting vibrations caused by the impact of water drops. Such detection can be performed by evaluating the measurement data of camera sensors, LIDAR sensors, rain sensors, etc.

[0019] According to a further embodiment, the measurement data of at least one camera sensor and / or at least one rain sensor are evaluated in order to detect splashing water in the surroundings of the ambient heat exchanger. Thus, a camera already mounted on the windshield in many vehicles can detect water spray or rain by image recognition. Alternatively, a rain sensor on the windshield can be used to detect splashing water. Such sensors are already in use and can therefore be used as a reliable data source for determining operating conditions that are unfavorable to the heat pump.

[0020] The measured data of at least one rain sensor arranged adjacent to the ambient heat exchanger are evaluated in order to detect splash water, whereby the difference between water spray at the location of the ambient heat exchanger and water spray or splash water at the location of the windshield can be eliminated. This can preferably be achieved by means of a rain sensor at the level of the ambient heat exchanger.

[0021] According to a further embodiment, the occurrence of splash water is detected by evaluating at least one parameter of a refrigerant compressor of the heat pump. Depending on the degree of icing of the ambient heat exchanger, the refrigerant compressor needs to be operated at a higher power in order to provide thermal power to the interior heat exchanger. This power consumption of the refrigerant compressor can be used to determine the degree of icing and also to detect splash water.

[0022] The presence of splash water is determined based on a change in the ratio of the freezing time to the defrosting time of the ambient heat exchanger relative to a reference ratio, whereby the presence of splash water can be detected in a particularly technically simple manner by evaluating at least one parameter of the refrigerant compressor of the heat pump. The determination of rain or water spray can thus be carried out internally by the heat pump control. In this case, the usual times for defrosting and operating processes of the heat pump can be used in relation to freezing processes or operating processes that are significantly longer than defrosting processes.

[0023] The quotient of the duration of a typical operating process until the ambient heat exchanger freezes over the duration for the subsequent defrosting of the ambient heat exchanger can be defined as a reference ratio.

[0024] In the case of water spray or rain on the surface of the ambient heat exchanger, this ratio decreases compared to the reference ratio, since the operating period until the ambient heat exchanger freezes is shortened. Based on this change, when adjusting the heat pump, it can be inferred from the ratio of the defrost time to the freezing time that the heat pump is operating under water spray or rain. This deviation can be used to avoid inefficient operating states.

[0025] A further aspect of the invention relates to a motor vehicle having a heat pump for carrying out the method according to the invention. In this case, the interior heat exchanger of the heat pump can be used to cool or heat the interior of the motor vehicle. Alternatively, the interior heat exchanger can also be used to heat or cool vehicle components, such as a traction battery or power electronics.

[0026] In the heating operation of the vehicle interior, the ambient heat exchanger coupled to the interior heat exchanger via the refrigerant circuit cools down. In this case, frost forms over time on the surface of the ambient heat exchanger. Splashing water can also accelerate the freezing of the ambient heat exchanger. Due to the frost or ice layer on the surface of the ambient heat exchanger, the efficiency of the heat pump is reduced and the heating performance of the interior or passenger compartment is impaired. The efficiency is reduced due to the need to carry out defrosting operations of the ambient heat exchanger more frequently.

[0027] The method can prevent or slow down the formation of ice on the surface of the ambient heat exchanger due to the influence of splashing water. To this end, the presence of splashing water, water spray or rain is detected and measures are initiated, for example by a controller, to slow down or prevent the icing of the ambient heat exchanger. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The embodiments of the present invention are described in detail below with the aid of the accompanying drawings. In the accompanying drawings:

[0029] Figure 1 A schematic diagram of a motor vehicle according to the invention is shown, which has a heat pump according to one specific embodiment;

[0030] Figure 2 Schematic diagram showing the pressure loss coefficient on the air side of an ambient heat exchanger, illustrating accelerated icing due to splash water.

[0031] In the drawings, the same structural elements are respectively provided with the same reference numerals. DETAILED DESCRIPTION

[0032] Figure 1A schematic side view of a motor vehicle 100 is shown, which has a heat pump 10 for air treatment according to one embodiment. The heat pump 10 is used, by way of example, to regulate the temperature in a passenger compartment 101 of the motor vehicle 100. The motor vehicle 100 is designed as a passenger car. The heat pump 10 can be used similarly for any motor vehicle 100, for example a truck, a bus, an agricultural vehicle, etc.

[0033] The heat pump 10 has an ambient heat exchanger 20 which is thermally coupled to the environment U or the ambient air. Therefore, in the heating operation of the heat pump 10 , the ambient heat exchanger 20 can extract heat from the environment U. In the heating operation of the heat pump 10 , the ambient heat exchanger 20 can be designed as an evaporator, for example.

[0034] Furthermore, the heat pump 10 has an interior heat exchanger 40 . The interior heat exchanger 40 is thermally connected to the passenger compartment 101 in order to heat or cool the passenger compartment 101 depending on the operating state of the heat pump 10 .

[0035] The ambient heat exchanger 20 and the interior heat exchanger 40 are fluidically connected to one another via a refrigerant circuit 50. A refrigerant can be conveyed through the refrigerant circuit 50 by means of a refrigerant compressor 51 in order to be able to extract heat from the environment U and to supply heat to the passenger compartment 101.

[0036] Due to the heat taken from the environment U, the ambient heat exchanger 20 may freeze and thus fail. In order to enable the heat pump 10 to operate for a long time, it is necessary to regularly de-ice the ambient heat exchanger 20. This is achieved by Figure 2 The defrost process A described in detail is implemented.

[0037] To carry out the defrosting process A, for example, the heat pump 10 can be operated in the opposite direction to the heating operation in order to briefly heat the ambient heat exchanger 20 .

[0038] Since rain and splash water S reach the ambient heat exchanger 20, ice layers can form on the ambient heat exchanger 20 more quickly and impair the operation of the heat pump 10. More frequent defrost processes A are therefore required, which results in a shortened operating time and reduced energy efficiency of the heat pump 10.

[0039] The controller 60 may be connected to the refrigerant compressor 51 and may be provided for controlling the heat pump 10. The controller 60 may implement a request for a heating power or a cooling power of the heat pump 10 in particular in the form of adjusting an operating state of the heat pump 10.

[0040] The controller 60 is also connected to a plurality of sensors 70, 71, 72 in a data-transmitting manner in order to register the presence of splash water S in the surroundings U of the ambient heat exchanger 20. This can preferably be achieved by receiving and evaluating the measurement data of the sensors 70, 71, 72.

[0041] In the illustrated embodiment, the sensors 70, 71, 72 are designed as a camera sensor 70, a first rain sensor 71 and a second rain sensor 72. The camera sensor 70 and the first rain sensor 71 are arranged in the region of the windshield 102 of the motor vehicle 100. The second rain sensor 72 is positioned adjacent to the ambient heat exchanger 20 in order to accurately determine whether the ambient heat exchanger 20 is acted upon by splash water S.

[0042] If it is determined by the controller 60 that the splash water S affects the ambient heat exchanger 20 , the heat pump 10 for heating the interior space heat exchanger 40 may be operated at an evaporation temperature in the ambient heat exchanger 20 higher than the freezing temperature of the splash water S to prevent the ambient heat exchanger 20 from freezing.

[0043] Alternatively, at least one alternative heat source 80, 81 can be used to directly or indirectly heat the interior heat exchanger 40. For example, heat can be taken from at least one heat source 80, 81 designed as a vehicle component. In the exemplary embodiment shown, heat from the power electronics 80 and the traction battery 81 of the motor vehicle 100 can be taken and used to directly heat the passenger compartment 101.

[0044] The alternative heat sources 80, 81 can be used for indirect heating of the passenger compartment 101 by means of the traction component heat exchanger 21. For this purpose, the traction component heat exchanger 21 can be connected in series with the ambient heat exchanger 20 or connected to the refrigerant circuit 50 instead of the ambient heat exchanger 20 damaged by the splash water S. An exemplary connecting line 22 of the traction component heat exchanger 21 to the refrigerant circuit 50 is schematically shown.

[0045] In this case, the traction component heat exchanger 21 can take the heat required for heating the passenger compartment 101 from the heat sources 80 , 81 and can therefore be used to bridge the ambient heat exchanger 20 or relieve the ambient heat exchanger 20 of its load.

[0046] Figure 2 A schematic diagram showing the pressure loss coefficient ζ on the air side of the ambient heat exchanger 20 for illustrating the accelerated icing due to the influence of splash water S. The pressure loss coefficient ζ on the air side of the ambient heat exchanger 20 varies with time or operating time t.

[0047] The pressure loss coefficient ζ on the air side of the ambient heat exchanger 20 is a dimensionless value for the pressure loss at the ambient heat exchanger 20 and is used to illustrate the consequences of ice formation. As ice formation increases, the ambient heat exchanger 20 can take less heat from the surrounding environment U and thus reduce the efficiency of the heat pump 10. In order to eliminate ice formation on the ambient heat exchanger 20, a defrosting process A is started. The ice formation on the ambient heat exchanger 20 can be eliminated by the defrosting process A, so that the pressure loss coefficient ζ on the air side increases again. Due to the influence of the splashing water S, the degree of ice formation is reached more quickly, so that more frequent defrosting processes A' are required.

[0048] The diagram shows a reference curve 90 of the air-side pressure loss coefficient ζ in normal operation or when the ambient heat exchanger 20 is not damaged by splash water S, and a curve 91 when the ambient heat exchanger 20 is damaged by splash water S.

[0049] The occurrence of splash water S can be detected by evaluating at least one parameter of the refrigerant compressor 51 of the heat pump 10 by the controller 60. The occurrence of splash water S can be determined by a change in the ratio of the freezing duration 92 of the ambient heat exchanger 20 to the defrosting process A' duration 94 relative to a reference ratio of a reference freezing duration 93 to a reference defrosting process A duration 95.

[0050] The quotient of the duration of a normal operation process or a reference freezing time 93 until the ambient heat exchanger 20 is frozen and the subsequent defrosting time 95 or the defrosting process A time 95 of the ambient heat exchanger 20 can be defined as a reference ratio.

[0051] Reference numerals list

[0052] 100 Motor Vehicles

[0053] 101 Passenger compartment / vehicle interior

[0054] 102 Windshield

[0055] 10Heat Pump

[0056] 20 Environmental Heat Exchanger

[0057] 21 Traction component heat exchanger

[0058] 22 Connection pipes of traction component heat exchanger

[0059] 40Internal space heat exchanger

[0060] 50 Refrigerant circulation circuit

[0061] 51 Refrigerant compressor

[0062] 60 Controller

[0063] 70 Camera Sensor

[0064] 71 First Rain Sensor

[0065] 72 Second rain sensor

[0066] 80 Power Electronic Equipment / Alternative Heat Sources

[0067] 81 Traction battery / alternative heat source

[0068] Reference curve of pressure loss coefficient ζ on the 90° air side

[0069] 91 Curve of pressure loss coefficient ζ on the air side under the influence of splash water

[0070] 92 Running time / freezing time under the influence of splash water

[0071] 93 Reference running time / reference freezing time

[0072] 94 Defrost duration under the influence of splash water

[0073] 95 Reference defrosting process duration

[0074] ζPressure loss coefficient on the air side

[0075] A Reference defrosting process

[0076] A'Defrosting process under the influence of splash water

[0077] S Splash Water

[0078] t time / running time

[0079] U Ambient The surroundings of the heat exchanger

Claims

1. A method for operating a heat pump (10), in particular a heat pump in a motor vehicle (100), the heat pump (10) having an ambient heat exchanger (20) and an interior heat exchanger (40) which are connected to one another via a refrigerant circuit (50), characterized in that: Detecting the presence of splash water (S) in the surroundings (U) of the ambient heat exchanger (20), wherein, when the presence of splash water (S) is detected, a heat pump (10) for heating an interior space heat exchanger (40) is operated at an evaporation temperature in the ambient heat exchanger (20) that is higher than the freezing temperature of the splash water (S), or the interior space heat exchanger (40) is heated directly or indirectly using heat from at least one alternative heat source (80, 81), wherein the presence of splash water (S) is detected by evaluating at least one parameter of a refrigerant compressor (51) of the heat pump (10), wherein the presence of splash water (S) is determined based on a change in a ratio of a freezing duration (92) to a defrosting duration (94) of the ambient heat exchanger (20) relative to a reference ratio (93, 95).

2. The method according to claim 1, wherein: The heat of at least one vehicle component, in particular a drive component, a traction battery (81) and / or a power electronics device (80), as an alternative heat source (80, 81) is used to directly heat the passenger compartment (101).

3. The method according to claim 2, wherein: The heat pump (10) is deactivated while the interior heat exchanger (40) is directly heated using heat from at least one alternative heat source (80, 81).

4. The method according to claim 1, wherein: The heat of at least one vehicle component, in particular a drive component, a traction battery (81) and / or a power electronics device (80), as an alternative heat source (80, 81) is used for indirect heating of the vehicle interior (101) by heating at least one traction component heat exchanger (21) connectable to the refrigerant circuit (50).

5. The method according to any one of claims 1 to 4, wherein: The occurrence of splashing water (S) is detected by evaluating measurement data of at least one sensor (70, 71, 72).

6. The method according to any one of claims 1 to 5, wherein: Measurement data of at least one camera sensor (70) and / or at least one rain sensor (71, 72) are evaluated in order to detect splash water (S) in the surroundings (U) of the ambient heat exchanger (20).

7. The method according to claim 6, wherein: Measurement data of at least one second rain sensor (72) arranged adjacent to the ambient heat exchanger (20) are evaluated in order to detect splash water (S).

8. A motor vehicle (100) having a heat pump (10) for carrying out the method according to any one of the preceding claims.

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