Patent ID: 11940164
Assignee: MITSUBISHI HEAVY INDUSTRIES THERMAL SYSTEMS, LTD.
Field: Thermal processes and apparatus (Mechanical engineering)
Classification: CPC F  B | IPC B  F

Claim 3:
4. A control method of a vehicle air conditioning system having a refrigerant circuit for cooling in which a compressor, switching means, a vehicle-cabin-exterior condenser, first decompression means, and a vehicle-cabin-interior evaporator provided in an HVAC unit are connected in this order,
a refrigerant circuit for heating in which the compressor, the switching means, a vehicle-cabin-interior condenser, second decompression means, and a vehicle-cabin-exterior evaporator are connected in this order,
a refrigerant that has high flammability, has a range of explosion near a normal temperature, and flows through the refrigerant circuit for cooling and the refrigerant circuit for heating,
an outside air temperature sensor that detects an outside air temperature, and
a pressure sensor that detects a pressure of the refrigerant, the control method comprising:
a step of calculating a refrigerant density as a density of the refrigerant based on the outside air temperature and the pressure; and
a step of determining whether or not the refrigerant density falls below a predetermined threshold value based on an amount of filled refrigerant, a total volume of the refrigerant circuit for cooling and the refrigerant circuit for heating, a volume of a vehicle cabin, a standard density of atmosphere, and an explosion limit of the refrigerant.