Vehicular air-conditioning apparatus and air-conditioning method of vehicular air-conditioning apparatus

A vehicle air-conditioning apparatus comprising:

• a refrigeration cycle device attached to a vehicle and including a compressor, the refrigeration cycle device being configured to form, with the compressor, refrigeration cycle for air cooling of a passenger compartment of the vehicle, the compressor being configured to circulate refrigerant in the refrigeration cycle;
• an outdoor air damper device switchable between an opened state in which outdoor air is allowed to be taken into the passenger compartment and a closed state in which the outdoor air is blocked from being taken into the passenger compartment;
• an outdoor air intake fan to form, when the outdoor air damper device in the opened state is operated, airflow to take the outdoor air into the passenger compartment through the outdoor air damper device;
• an outdoor air temperature measurer to detect an outdoor air temperature that is a temperature of the outdoor air;
• an indoor temperature measurer to detect an indoor temperature that is a temperature in the passenger compartment;
• and
• a controller to perform
• refrigeration cycle control to cause the refrigeration cycle device to air-cool the passenger compartment, and
• free cooling control to take the outdoor air into the passenger compartment by controlling the outdoor air damper device to be in the opened state and activating the outdoor air intake fan, while the compressor is stopped,
• wherein the controller performs
• a prior determination by determining whether the air cooling of the passenger compartment by the free cooling control is possible, based on a predetermined target value of the temperature in the passenger compartment, the outdoor air temperature measured with the outdoor air temperature measurer, and the indoor temperature measured with the indoor temperature measurer, and
• stop control by causing stoppage of the outdoor air intake fan while the compressor is kept stopped, when the indoor temperature is estimated to be a temperature close to the target value after determining, during performing of the free cooling control, whether the indoor temperature is estimated to be a temperature close to the target value due to communication between the passenger compartment and an outside during a period in which the vehicle stands at a next station, the free cooling control being performed after the prior determination in which the air cooling of the passenger compartment by the free cooling control is determined to be possible.

A method for air-conditioning by a vehicle air-conditioning apparatus, the method comprising:

• a prior determination step of determining whether air cooling of a passenger compartment of a vehicle by free cooling control that takes outdoor air into the passenger compartment with an outdoor air intake fan is possible while a refrigeration cycle device attached to the vehicle for air cooling of the passenger compartment is stopped;
• and
• a free cooling execution determination step of determining, upon the air cooling of the passenger compartment by the free cooling control being determined to be possible in the prior determination step, whether to perform the free cooling control by comparing a free cooling performance value and an indoor heat load value, wherein
• the free cooling performance value depends on a temperature difference between an outdoor air temperature that is a temperature of the outdoor air and an indoor temperature that is a temperature in the passenger compartment, and indicates a capacity of air cooling by the free cooling control, and
• the indoor heat load value depends on a vehicle occupancy rate of passengers in the passenger compartment and indicates a difficulty of a temperature decrease in the passenger compartment.