US 11,940,164 B2
Vehicle air conditioning system and control method of vehicle air conditioning system
Takayuki Hagita, Tokyo (JP); Nobuya Nakagawa, Tokyo (JP); and Hideto Noyama, Tokyo (JP)
Assigned to MITSUBISHI HEAVY INDUSTRIES THERMAL SYSTEMS, LTD, Tokyo (JP)
Appl. No. 17/438,638
Filed by MITSUBISHI HEAVY INDUSTRIES THERMAL SYSTEMS, LTD., Tokyo (JP)
PCT Filed Feb. 12, 2020, PCT No. PCT/JP2020/005246
§ 371(c)(1), (2) Date Sep. 13, 2021,
PCT Pub. No. WO2020/189099, PCT Pub. Date Sep. 24, 2020.
Claims priority of application No. 2019-048502 (JP), filed on Mar. 15, 2019.
Prior Publication US 2022/0221177 A1, Jul. 14, 2022
Int. Cl. F24F 11/36 (2018.01); B60H 1/24 (2006.01); F24F 11/50 (2018.01); F24F 11/89 (2018.01); F25B 49/02 (2006.01)
CPC F24F 11/36 (2018.01) [B60H 1/24 (2013.01); F24F 11/50 (2018.01); F24F 11/89 (2018.01); F25B 49/02 (2013.01); F25B 2500/222 (2013.01); F25B 2700/19 (2013.01); F25B 2700/2106 (2013.01)] 4 Claims
OG exemplary drawing
 
1. A vehicle air conditioning system comprising:
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;
a pressure sensor that detects a pressure of the refrigerant; and
a control device that calculates a refrigerant density as a density of the refrigerant based on the outside air temperature and the pressure, and determines 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.
 
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.