METHOD FOR INITIATING A DEFROSTING PROCESS OF A HEAT EXCHANGER 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 parameters influencing the air flow through the evaporator, and with which method unnecessary defrosting processes can be avoided, wherein a fan is assigned to the heat exchanger, wherein a power consumption and/or a speed of the fan is monitored, a defrosting process is initiated when the power consumption and/or the speed exceeds and/or falls below a threshold value, and the threshold value is determined as a function of a parameter, wherein the parameter is an indicator of a current relative air speed of the ambient air in relation to the motor vehicle.

Claims

1. A method for initiating a defrosting process of a heat exchanger of a heat pump of a motor vehicle , wherein a fan is assigned to the heat exchanger, comprising: monitoring a power consumption and/or a speed of the fan, initiating a defrosting process when the power consumption and/or the speed exceeds and/or falls below a threshold value, wherein the threshold value is determined as a function of a parameter, wherein the parameter is an indicator of a current relative air speed of ambient air in relation to the motor vehicle.

2. The method according to claim 1, wherein the parameter is the current driving speed of the motor vehicle.

3. The method according to claim 1, wherein the parameter is the wind speed and/or the wind direction.

4. The method according to claim 1, wherein the parameter is a distance signal.

5. The method according to claim 4, 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.

6. The method according to claim 1, wherein the parameter is a vehicle position.

7. The method according to claim 4, wherein the vehicle position is a position of the motor vehicle in a road tunnel, in a valley, or in a street canyon.

8. The method according to claim 1, wherein the threshold value is determined as a function of a dew point temperature of the air at the heat exchanger, and/or wherein the defrosting process is only initiated when the temperature of the air at the heat exchanger falls below the dew point temperature.

9. The method according to claim 1, wherein the threshold value is determined as a function of the air density and/or the outside air temperature and/or the outside air humidity, and/or wherein the parameter is an opening degree of a radiator shutter.

10. The method according to claim 1, wherein the fan is operated for a short period of time at an increased or a decreased speed to determine whether a defrosting process should be initiated.

11. The method according to claim 1, wherein the method is carried out when the motor vehicle is stationary or at a low driving speed.

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

13. A motor vehicle comprising: a device for defrosting a heat exchanger of a heat pump of the motor vehicle, a fan assigned to the heat exchanger, has a computing unit that is designed 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 figures.

[0049] In the figures:

[0050] FIG. 1 shows a motor vehicle with a device for defrosting a heat exchanger of a heat pump, and

[0051] FIG. 2 is a block diagram of a method for initiating a defrosting process of a heat exchanger.

DETAILED DESCRIPTION OF THE INVENTION

[0052] FIG. 1 shows a motor vehicle 200 having a heat pump 10. The heat pump 10 comprises a heat exchanger 11 for absorbing heat from the ambient air 12. A fan 13 is assigned to the heat exchanger 11 of the heat pump 10, which fan is designed to conduct an air flow through the heat exchanger 11. The speed of the fan 13 can be determined by means of a speed sensor 14. The power consumption of the fan 13 is read out via a bus signal. The motor vehicle 200 also comprises a driving speed sensor 15, a distance sensor system 16, a temperature sensor 17, and a navigation system 18. The current driving speed of the motor vehicle 200 is determined with the driving speed sensor 15. The distance sensor system 16 generates a distance signal when the motor vehicle 200 drives behind a vehicle traveling in front. A specific distance value in meters to the vehicle traveling in front can preferably be determined by means of the distance sensor system 16. A vehicle position of motor vehicle 200 can be determined by means of the navigation system 18. In particular, it can be determined whether the motor vehicle 200 is in a tunnel, in a valley, or in a street canyon. The outside air temperature can finally be determined with the temperature sensor 17. These parameters determined with the sensors are indicators for a current relative air speed of the ambient air 12 in relation to the motor vehicle 200.

[0053] The speed of the fan 13 and the power consumption thereof as well as the driving speed of the motor vehicle 200, the distance signal, the vehicle position, and the outside air temperature are transmitted to a computing unit 19 of a device 20 for defrosting the heat exchanger 11. The computing unit 19 first determines a current speed threshold value and/or a current power consumption threshold value on the basis of at least one of the parameters driving speed, distance signal, vehicle position, or outside air temperature.

[0054] The power consumption and/or the speed of the fan 13 are then compared with the corresponding threshold value, in particular the power consumption threshold value and/or the speed threshold value, in the computing unit 19. When the speed and/or the power consumption exceeds or falls below the corresponding threshold value, the computing unit 19 instructs the device 20 to perform a defrosting process for the heat exchanger 11.

[0055] FIG. 2 shows a block diagram of a method 100 for initiating a defrosting process of a heat exchanger 11 of a heat pump 10 of a motor vehicle 200.

[0056] First of all, in a first method step S1, the current speed and/or the current power consumption of the fan 13 assigned to the heat exchanger 11 are determined. Furthermore, at least one of the parameters driving speed of the motor vehicle, distance between the motor vehicle and a vehicle traveling in front, vehicle position, and outside air temperature is determined. A threshold value, in particular a power consumption threshold value and/or a speed threshold value, is then determined from these parameters in a second method step S2. In a third method step S3, the current power consumption and/or the current speed is compared with the power consumption threshold value and/or the speed threshold value. When the power consumption or the speed falls below or exceeds the power consumption threshold value or the speed threshold value, a defrosting process for the heat exchanger 11 is initiated. Defrosting of the heat exchanger 11 can take place, for example, by a heating element of the device 20 for defrosting the heat exchanger 11.

LIST OF REFERENCE SIGNS

[0057] 100 Method

[0058] 200 Motor vehicle

[0059] 10 Heat pump

[0060] 11 Heat exchanger

[0061] 12 Ambient air

[0062] 13 Fan

[0063] 14 Speed sensor

[0064] 15 Driving speed sensor

[0065] 16 Distance sensor system

[0066] 17 Temperature sensor

[0067] 18 Navigation system

[0068] 19 Computing unit

[0069] 20 Device

[0070] S1-S3 Method steps