METHOD FOR INITIATING A DEFROSTING PROCESS OF A HEAT EXHANGER OF A HEAT PUMP OF A MOTOR VEHICLE

Abstract

In order to provide a method for initiating a defrosting process of a heat exchanger of a heat pump of a motor vehicle, which method is insensitive to external influences and can also be used in combination with other methods, wherein the heat exchanger and a coolant heat exchanger of a cooling circuit of the motor vehicle are arranged in a common air path, a coolant outlet temperature of a coolant from the coolant heat exchanger is determined, and a state of icing of the heat exchanger is determined using the coolant outlet temperature, and initiating a defrosting process of the heat exchanger if icing of the heat exchanger is determined.

Claims

1. A method for initiating a defrosting process of a heat exchanger of a heat pump of a motor vehicle, wherein the heat exchanger and a coolant heat exchanger of a cooling circuit of the motor vehicle are arranged in a common air path, comprising: determining a coolant outlet temperature of a coolant from the coolant heat exchanger, determining a state of icing of the heat exchanger using the coolant outlet temperature, and initiating a defrosting process of the heat exchanger if icing of the heat exchanger is determined.

2. The method according to claim 1, wherein the state of icing of the heat exchanger is determined from a change in the coolant outlet temperature.

3. The method according to claim 2, wherein the change in the coolant outlet temperature is an increase.

4. The method according to claim 1, further comprising: determining a coolant inlet temperature of the coolant in the coolant heat exchanger, and determining a coolant temperature difference from the coolant inlet temperature and the coolant outlet temperature, and wherein the state of icing of the heat exchanger is determined from a change in the coolant temperature difference.

5. The method according to claim 4, wherein the change in the coolant temperature difference is a decrease.

6. The method according to claim 1, further comprising determining a coolant volume flow and/or a performance of a coolant pump of the cooling circuit, wherein the coolant volume flow and/or the performance of the coolant pump is used to determine the state of icing of the heat exchanger.

7. The method according to claim 1, wherein the cooling circuit is operated for the determination of the state of icing, and the cooling circuit is operated over a specific period of time for the determination of the state of icing.

8. The method according to claim 7, wherein the specific period of time is less than 30 seconds.

9. The method according to claim 1, wherein a coolant temperature is increased or decreased when the coolant temperature corresponds approximately to an ambient temperature.

10. The method according to claim 7, wherein the coolant temperature is coolant inlet temperature.

11. The method according to claim 1, wherein a parameter is used to determine the state of icing, and wherein the parameter is an indicator of a current relative air speed of the ambient air in relation to the motor vehicle.

12. The method according to claim 11, wherein the parameter is the current driving speed of the motor vehicle, the wind speed and/or the wind direction.

13. The method according to claim 11, wherein the parameter is a distance signa.

14. The method according to claim 13, wherein the distance signal is the distance value is of the motor vehicle in relation to a vehicle traveling in front of the motor vehicle.

15. The method according to claim 11, wherein the parameter is a vehicle position.

16. The method according to claim 15, wherein the vehicle position is a position of the motor vehicle in a road tunnel, in a valley, or in a street canyon.

17. The method according to claim 1, wherein the motor vehicle is an electric vehicle, a battery-electric vehicle or a hybrid electric vehicle.

18. A motor vehicle (200), comprising: a device for defrosting a heat exchanger of a heat pump of the motor vehicle, wherein the device has a computing unit that is configured to carry out the method according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The present invention is explained in more detail below with reference to the accompanying figure.

[0049] FIG. 1 is a schematic representation of a motor vehicle with a heat exchanger of a heat pump and a coolant heat exchanger of a cooling circuit.

DETAILED DESCRIPTION OF THE INVENTION

[0050] A method 100 for initiating a defrosting process of a heat exchanger 10 of a heat pump 11 of a motor vehicle 200, which is only shown schematically, is explained with reference to FIG. 1. The motor vehicle 200 is designed as a battery-electric vehicle 12. The heat pump 11 of the motor vehicle 200 is used to heat a passenger compartment of the motor vehicle 200. A coolant heat exchanger 13 of a cooling circuit 14 for the electric drive and the battery of the motor vehicle 200 is arranged in the same air path 15 together with the heat exchanger 10 of the heat pump 11. In the cooling circuit 14, a first temperature sensor 16 is provided on the outlet side of the coolant heat exchanger 13, with which a coolant outlet temperature of the coolant from the coolant heat exchanger 13 is determined. In the cooling circuit 14, a second temperature sensor 17 for the determination of the coolant inlet temperature into the coolant heat exchanger 13 is also provided on the inlet side of the coolant heat exchanger 13. The sensor data of the first temperature sensor 16 and the second temperature sensor 17 are forwarded to a computing unit 18 of the motor vehicle 200, which computing unit calculates a coolant temperature difference from the coolant inlet temperature and the coolant outlet temperature and uses the coolant temperature difference and/or the coolant outlet temperature to determine a state of icing of the heat exchanger 10 of the heat pump 11. If icing of the heat exchanger 10 is present, a defrosting process of the heat exchanger 10 is initiated. For this purpose, methods known from the prior art, such as the use of a heating element 19, can be used.

[0051] In addition, the performance of a coolant pump 20 and a coolant volume flow in the cooling circuit 14 are determined by means of further sensors 21, 22 and transmitted to the computing device 18. The computing device 18 uses the determined performance of the coolant pump 20 and the determined coolant volume flow in addition to the coolant temperature difference and/or the coolant outlet temperature in order to infer the state of icing of the heat exchanger 10.

[0052] Since the cooling circuit 14 is usually not operated continuously to cool the electric drive or the battery of the motor vehicle 200, the computing device 18 is also designed to operate the cooling circuit 14 at periodic intervals, for example for a period of approximately 30 seconds, for the determination of the state of icing of the heat exchanger 10 of the heat pump 11. In the event that the coolant temperature in the cooling circuit 14 substantially corresponds to the ambient temperature so that no heat transfer can take place, the coolant temperature, in particular the coolant inlet temperature, can be increased by means of a PTC heating element 23.

[0053] In addition to the aforementioned parameters, the computing unit 18 can also use further parameters to determine the state of icing of the heat exchanger 10 of the heat pump 11. For example, the distance signals from a distance sensor system 24 can be used to determine a distance between the motor vehicle 200 and a vehicle traveling in front, and/or measured values from a sensor system 25 can be used to determine a wind speed. The motor vehicle 200 also comprises a navigation system 26, the information of which, which information relates to the position of the motor vehicle 200, can also be used to determine the state of icing of the heat exchanger 10.

LIST OF REFERENCE SIGNS

[0054] 100 Method [0055] 200 Motor vehicle [0056] 10 Heat exchanger [0057] 11 Heat pump [0058] 12 Battery-electric vehicle [0059] 13 Coolant heat exchanger [0060] 14 Cooling circuit [0061] 15 Air path [0062] 16 First temperature sensor [0063] 17 Second temperature sensor [0064] 18 Computing unit [0065] 19 Heating element [0066] 20 Coolant pump [0067] 21 Sensor [0068] 22 Sensor [0069] 23 PTC heating element [0070] 24 Distance sensor system [0071] 25 Sensor system [0072] 26 Navigation system