METHOD FOR OPERATING AN AIR-CONDITIONING SYSTEM FOR A VEHICLE

Abstract

The invention relates to a method for operating a climate-control system (12) for a vehicle (10). According to the invention, total energy efficiencies are determined for a group of operating strategies for the air-conditioning system (12) and an operating strategy with the greatest total efficiency that fulfills the heating output requirement (44) that has been determined, is selected.

Claims

1. A method for operating a climate-control system for a vehicle, whereby the climate-control system comprises: a heat pump with an outside-air heat exchanger, and an additional heating heat source for an interior of the vehicle, the method comprises the following steps: determining a heating output demand for the climate-control of the vehicle; determining a thus required heat output uptake at the outside-air heat exchanger; determining an outside-air state; determining a fluid temperature in the outside-air heat exchanger that is needed for the required heat output uptake; determining whether the value of the required fluid temperature falls below a dew point of the outside air at the outside-air heat exchanger; and selecting an operating strategy for the climate-control system from a group that comprises at least the following operating strategies: b) meeting part of the heating output demand by operating the heat pump at a fluid temperature whose value does not fall below the dew point, and meeting the rest of the heating output demand by operating the additional heating heat source; and d) temporarily meeting the heating output demand by operating the heat pump at a fluid temperature whose value falls below the dew point, followed by a thawing phase of the outside-air heat exchanger; whereby the selection of the operating strategy is made on the basis of criteria that comprise at least meeting the heating output demand and maximizing the overall efficiency of the climate-control system.

2. The method according to claim 1, wherein the group comprises the following additional operating strategy: a) meeting the heating output demand by operating the heat pump at a fluid temperature whose value does not fall below the dew point.

3. The method according to claim 2, wherein the group comprises the following additional operating strategy: c) temporarily meeting part of the heating output demand by operating the heat pump at a fluid temperature whose value falls below the dew point, and meeting the rest of the heating output demand by operating the additional heating heat source, followed by a thawing phase of the outside-air heat exchanger.

4. The method according to claim 3, wherein, in operating strategy c) or d), the heating output demand during the thawing phase is met by operating the additional heating heat source, and heat from the additional heating heat source is used to thaw the outside-air heat exchanger, and wherein additionally, a heat pumping process of the heat pump is reversed, whereby heat from the additional heating heat source counters the cooling effect that results from the reversal of the heat pumping process.

5. The method according to claim 3, wherein, in operating strategy c), a simulation, a predictive regulation or the use of an engine map are carried out on the basis of user information and of an icing model, whereby a determination is made as to when the heating output demand will be eliminated and then part of the heating output demand is met by operating the heat pump at a fluid temperature whose value falls below the dew point, and the rest of the heating output demand is met by operating the additional heating heat source, so that this operating strategy leads to a maximization of the total efficiency until the heating output demand is eliminated.

6. The method according to claim 3, wherein, in operating strategy c) or d), a simulation is carried out on the basis of user information and of an icing model as to when the heating output demand will be eliminated, and the heating output demand is met until the heating output demand is eliminated in that the heat pump is operated at a fluid temperature whose value falls below the dew point.

7. The method according to claim 1, wherein the additional heating heat source employed is an electric heating heat source.

8. The method according to claim 1, wherein the climate-control system employed is intended for an electric vehicle.

9. A control unit that is configured to carry out a method according to claim 1.

10. A vehicle comprising: a climate-control system with a heat pump, an outside-air heat exchanger, an additional heating heat source for an interior of the vehicle, and a control unit according to claim 9.

Description

[0049] The invention will be explained below in embodiments on the basis of the accompanying drawings. The following is shown:

[0050] FIG. 1 a climate-control system and a control unit according to the invention in a vehicle according to the invention; and

[0051] FIG. 2 a schematic depiction of the use of criteria for selecting an operating strategy.

[0052] The upper part of FIG. 1 shows an embodiment by way of example of a vehicle 10 according to the invention, with a climate-control system 12 and a control unit 14 according to the invention. Here, the vehicle 10 is an electric vehicle 16.

[0053] The lower part of FIG. 1 shows the principle of the climate-control system 12.

[0054] The climate-control system 12 of the electric vehicle 16 comprises a heat pump 18. The heat pump 18 has an outside-air heat exchanger 20 that can be operated as an evaporator. The latter is arranged in a motor compartment 22 of the electric vehicle 16 behind a grille 24. Moreover, the heat pump 18 comprises an inside-air heat exchanger 26 that can be operated as a condenser/gas cooler.

[0055] The inside-air heat exchanger 26 is arranged in an outflow channel 28. The outflow channel 28 also contains an additional heating heat source 30 that, in this case, comprises an electric heating heat source 32.

[0056] Air 34 can flow into an interior 36 of the electric vehicle 16 through the outflow channel 28, said air 34 having been previously drawn in as intake air 40 from the environment or from the interior 36 of the electric vehicle 16.

[0057] Outside air 38 flows through the grille 24 into the motor compartment 22 and it is conveyed along the outside-air heat exchanger 20.

[0058] Heat contained in the outside air 38 can enter the heat pump 18 through the outside-air heat exchanger 18 and can be released as heating output to the intake air 40 via the inside-air heat exchanger 26. Furthermore, the electric heating heat source 32 can generate electric heat and can likewise release it to the intake air 40.

[0059] The control unit 14 in the electric vehicle 16 is configured to operate the climate-control system 12 in the manner according to the invention.

[0060] In this context, FIG. 2 shows a schematic depiction of the use of criteria for selecting an operating strategy for the climate-control system 12.

[0061] In this process, the outside air temperature 42 is plotted on the vertical axis. A heating output demand 44 is plotted on the horizontal axis.

[0062] For the sake of simplification, the target temperature in the interior 36 of the vehicle 10 is assumed to be constant. The outside air humidity as well as the flow rate of a fluid in the outside-air heat exchanger 20 are likewise assumed to be constant.

[0063] By way of example, the diagram now qualitatively shows how different operating strategies a), b), c), d) can be selected in order to cover the heating output demand 44 while also achieving the greatest possible total efficiency of the climate-control system 12.

[0064] For example, in the method according to the invention, it can be determined that these criteria within the scope of the operating strategies a) can be met purely by heat pump operation without the outside-air heat exchanger 20 icing up.

[0065] Moreover, for example, in the method according to the invention, it can be determined that these criteria within the scope of the operating strategy c) can be met by heat pump operation in combination with the operation of the electric heating heat source 32, whereby the outside-air heat exchanger 20 ices up. Operating strategy c) is shown in two areas of the diagram in FIG. 2. In the front area, closer to the vertical axis, in other words, at a lower heating output demand 44, the thawing phase takes place passively by way of example once there is no longer a demand for climate control. In the rear area, further away from the vertical axis, in other words, at a higher heating output demand 44, the thawing phase takes place by way of example by reversing the heat pumping process while meeting the rest of the heating output demand 44 with the electric heating heat source 32.

LIST OF REFERENCE NUMERALS

[0066] 10 vehicle

[0067] 12 climate-control system

[0068] 14 control unit

[0069] 16 electric vehicle

[0070] 18 heat pump

[0071] 20 outside-air heat exchanger

[0072] 22 motor compartment

[0073] 24 grille

[0074] 26 inside-air heat exchanger

[0075] 28 outflow channel

[0076] 30 additional heating heat source

[0077] 32 electric heating heat source

[0078] 34 air

[0079] 36 interior

[0080] 38 outside air

[0081] 40 intake air

[0082] 42 outside temperature

[0083] 44 heating output demand