METHOD FOR OPERATING A HEAT PUMP FOR A MOTOR VEHICLE AND HEAT PUMP

Abstract

A method for operating a heat pump for a motor vehicle is proposed, wherein the heat pump comprises a refrigerant circuit with a refrigerant, an ambient heat exchanger, a compressor, a heating heat exchanger, and a throttle. The method comprises determining an expected start time of a charging process of a motor vehicle battery and determining a maximum dew point undershoot and/or a maximum frost mass. The method further comprises operating the heat pump such that the maximum dew point undershoot and/or the maximum frost mass are reached within a predefined time period before the expected start time.

Claims

1. A method for operating a heat pump of a motor vehicle, the heat pump comprising a refrigerant circuit with a refrigerant, the heat pump comprising an ambient heat exchanger, a compressor, a heating heat exchanger, and a throttle, the method comprising: determining an expected start time of a charging process of a motor vehicle battery; determining a maximum dew point undershoot and/or a maximum frost mass; and operating the heat pump such that the maximum dew point undershoot and/or the maximum frost mass are reached within a predefined time period before the expected start time.

2. The method according to claim 1, wherein the method further comprises initiating a defrosting process upon reaching the maximum dew point undershoot and/or upon reaching the maximum frost mass and/or upon initiating a battery charging process.

3. The method according to claim 1, wherein the method further comprises determining a minimum suction pressure of the refrigerant in the refrigerant circuit on the basis of the maximum dew point undershoot and/or the maximum frost mass.

4. The method according to claim 1, wherein operating the heat pump comprises controlling the compressor and/or the throttle.

5. The method according to claim 1, wherein determining the expected start time of the charging process takes into account a state of charge of the battery and/or a range of the motor vehicle and/or the expected vehicle operating time.

6. The method according to claim 1, wherein an air mass flow through the ambient heat exchanger and a partial pressure difference between the air and a surface of the ambient heat exchanger are determined for determining the maximum dew point undershoot and/or the maximum frost mass.

7. The method according to claim 6, wherein a cooling fan speed and/or a driving speed of the motor vehicle and/or wind speed are taken into account for determining the air mass flow.

8. The method according to claim 1, wherein the maximum dew point undershoot and/or the maximum frost mass are dynamically adjusted.

9. The method according to claim 2, wherein a cooling fan of the motor vehicle is operated continuously during the charging process at outside temperatures above 0° C. or after completion of the charging process.

10. A heat pump for a motor vehicle, wherein the heat pump comprises: an ambient heat exchanger; a compressor; a heating heat exchanger; and a throttle, wherein the heat pump is configured to perform the method according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0025] The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawing which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein the sole FIGURE shows a schematic diagram of a process diagram of a method of the invention.

DETAILED DESCRIPTION

[0026] The FIGURE shows a process diagram of a method 100 of the invention, which comprises determining 101 an expected start time of a charging process of a motor vehicle battery. Further, a maximum dew point undershoot and/or maximum frost mass are determined 103. Further, the method comprises operating 107 the heat pump such that maximum dew point undershoot and/or maximum frost mass are reached within a predefined time period before the expected start time.

[0027] To determine the expected start time of the charging process, a state of charge and/or a range and/or an expected vehicle operating time can be taken into account 102. A partial pressure difference between the air and a surface of the ambient heat exchanger and an air mass flow through the ambient heat exchanger can be determined to determine the maximum dew point undershoot and/or the maximum frost mass 104. For this purpose, a cooling fan speed and/or a driving speed of the motor vehicle and/or a wind speed can be taken into account 105.

[0028] A minimum suction pressure of the refrigerant in the refrigerant circuit can be determined on the basis of the determined maximum undershoot of the dew point and/or the maximum frost mass 106.

[0029] To operate the heat pump, the compressor and/or the throttle can be controlled accordingly 108. Depending on the specific conditions, for example, the use of a heat source other than outside air when operating in the heating mode, the maximum dew point undershoot and/or maximum frost mass can be dynamically adjusted 109.

[0030] The method 100 comprises initiating 110 a defrosting process upon reaching the maximum dew point undershoot and/or the maximum frost mass and/or upon initiating a battery charging process. During the charging process, the cooling fan is operated continuously 111.

[0031] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.