Vehicle air-conditioning system and operation control method therefor

A vehicle-air-conditioning-system operation control method for automatically operating a vehicle air-conditioning system,

• said vehicle air-conditioning system comprising:
• an HVAC unit that blows, into a vehicle interior, air whose temperature has been adjusted by a refrigerant evaporator and a second refrigerant condenser that are provided in a blowing path of a blower;
• a heat pump cycle in which a refrigerant compressor, a refrigerant circuit changeover section that changes a refrigerant circulating direction, a first refrigerant condenser that condenses refrigerant by performing heat exchange with outside air, a first expansion valve, and the refrigerant evaporator are connected in this order;
• a second expansion valve and a refrigerant/coolant heat exchanger are connected in parallel with the first expansion valve and the refrigerant evaporator;
• and the second refrigerant condenser is connected in parallel with the first refrigerant condenser via the refrigerant circuit changeover section;
• and
• a coolant cycle in which a coolant circulating pump, a ventilation-exhaust-heat recovery unit that recovers heat from exhaust air from the vehicle interior, a motor/battery, an electric heater, and the refrigerant/coolant heat exchanger are sequentially connected;
• and the ventilation-exhaust-heat recovery unit, the motor/battery, and the electric heater can be selectively used as a heat source,
• said method comprising the steps of:
• at the start of operation, reading predetermined setting values of temperature and pressure, detected values obtained from sensors provided at predetermined positions for detecting temperature and pressure, and control panel settings;
• if the blower has been turned off, performing motor/battery cooling control for performing refrigerant cooling of the motor/battery;
• if the blower has been turned on, determining whether an air-conditioning switch has been turned on or off;
• if the air-conditioning switch has been turned off, when a temperature adjusting dial is set at maximum cooling, performing blowing-mode control that includes refrigerant cooling of the motor/battery, and, when the temperature adjusting dial is not set at the maximum cooling, performing heating control;
• if the air-conditioning switch has been turned on, when the temperature adjusting dial is set at the maximum cooling, performing cooling control, and, when the temperature adjusting dial is not set at the maximum cooling, further determining whether it is necessary to prevent the evaporator from frosting;
• if it is necessary to prevent the evaporator from frosting, performing the heating control;
• and
• if it is not necessary to prevent the evaporator from frosting, performing dehumidifying and heating control.

A vehicle-air-conditioning-system operation control method for performing a heating control operation in a vehicle air-conditioning system,

• said vehicle air-conditioning system comprising:
• an HVAC unit that blows, into a vehicle interior, air whose temperature has been adjusted by a refrigerant evaporator and a second refrigerant condenser that are provided in a blowing path of a blower;
• a heat pump cycle in which a refrigerant compressor, a refrigerant circuit changeover section that changes a refrigerant circulating direction, a first refrigerant condenser that condenses refrigerant by performing heat exchange with outside air, a first expansion valve, and the refrigerant evaporator are connected in this order;
• a second expansion valve and a refrigerant/coolant heat exchanger are connected in parallel with the first expansion valve and the refrigerant evaporator;
• and the second refrigerant condenser is connected in parallel with the first refrigerant condenser via the refrigerant circuit changeover section;
• and
• a coolant cycle in which a coolant circulating pump, a ventilation-exhaust-heat recovery unit that recovers heat from exhaust air from the vehicle interior, a motor/battery, an electric heater, and the refrigerant/coolant heat exchanger are sequentially connected;
• and the ventilation-exhaust-heat recovery unit, the motor/battery, and the electric heater can be selectively used as a heat source,
• said method comprising the steps of:
• during heating control, determining whether a relationship between a coolant outlet temperature Tcmo of the motor/battery in the coolant cycle and a coolant outlet temperature Tcno of the refrigerant/coolant heat exchanger satisfies Tcmo>Tcno;
• if Tcmo is lower than Tcno, energizing the electric heater, heating coolant in the coolant cycle with the electric heater, and circulating, in the heat pump cycle, the refrigerant from the refrigerant compressor to the second refrigerant condenser, the second expansion valve, and the refrigerant/coolant heat exchanger, in this order, thus performing a heat-pump heating operation by using the coolant as a heat source;
• if the coolant outlet temperature Tcmo of the motor/battery is equal to or higher than the coolant outlet temperature Tcno of the refrigerant/coolant heat exchanger, determining whether the relationship between the coolant outlet temperature Tcho of the ventilation-exhaust-heat recovery unit and the coolant outlet temperature Tcno of the refrigerant/coolant heat exchanger satisfies Tcho>Tcno;
• if Tcho is lower than Tcno, further determining whether the relationship between a coolant inlet temperature Tcni of the refrigerant/coolant heat exchanger and a predetermined coolant inlet required temperature Tcni1 of the refrigerant/coolant heat exchanger satisfies Tcni<Tcni1;
• whether the relationship between an air-side outlet temperature Taso of the second refrigerant condenser and a predetermined air-side required outlet temperature Tasol of the second refrigerant condenser satisfies Taso<Tasol;
• and whether the relationship between an inlet refrigerant pressure Prsi of the second refrigerant condenser and a predetermined inlet required refrigerant pressure Prsi1 of the second refrigerant condenser satisfies Prsi<Prsi1;
• if each of the coolant inlet temperature Tcni, the air-side outlet temperature Taso, and the inlet refrigerant pressure Prsi does not satisfy the corresponding condition, heating coolant in the coolant cycle with exhaust heat of the motor/battery, and circulating, in the heat pump cycle, the refrigerant from the refrigerant compressor to the second refrigerant condenser, the second expansion valve, and the refrigerant/coolant heat exchanger, in this order, thus performing a heat-pump heating operation by using the coolant as the heat source;
• and
• if each of the coolant inlet temperature Tcni, the air-side outlet temperature Taso, and the inlet refrigerant pressure Prsi satisfies the corresponding condition, energizing the electric heater, heating the coolant in the coolant cycle with both the electric heater and the motor/battery, and performing the heat-pump heating operation by using the coolant as the heat source.

The vehicle-air-conditioning-system operation control method for performing a dehumidifying and heating control operation in a vehicle air-conditioning system,

• said vehicle air-conditioning system comprising:
• an HVAC unit that blows, into a vehicle interior, air whose temperature has been adjusted by a refrigerant evaporator and a second refrigerant condenser that are provided in a blowing path of a blower;
• a heat pump cycle in which a refrigerant compressor, a refrigerant circuit changeover section that changes a refrigerant circulating direction, a first refrigerant condenser that condenses refrigerant by performing heat exchange with outside air, a first expansion valve, and the refrigerant evaporator are connected in this order;
• a second expansion valve and a refrigerant/coolant heat exchanger are connected in parallel with the first expansion valve and the refrigerant evaporator;
• and the second refrigerant condenser is connected in parallel with the first refrigerant condenser via the refrigerant circuit changeover section;
• and
• a coolant cycle in which a coolant circulating pump, a ventilation-exhaust-heat recovery unit that recovers heat from exhaust air from the vehicle interior, a motor/battery, an electric heater, and the refrigerant/coolant heat exchanger are sequentially connected;
• and the ventilation-exhaust-heat recovery unit, the motor/battery, and the electric heater can be selectively used as a heat source,
• said method comprising the steps of:
• during dehumidifying and heating control, determining whether a relationship between a coolant outlet temperature Tcmo of the motor/battery in the coolant cycle and a coolant outlet temperature Tcno of the refrigerant/coolant heat exchanger satisfies Tcmo>Tcno;
• and
• if Tcmo is lower than Tcno, energizing the electric heater, heating coolant in the coolant cycle with the electric heater, condensing, in the heat pump cycle, the refrigerant from the refrigerant compressor at the second refrigerant condenser, and concurrently circulating the refrigerant to the first expansion valve and the refrigerant evaporator and to the second expansion valve and the refrigerant/coolant heat exchanger, thus performing a heat-pump dehumidifying and heating operation by using the coolant as a heat source.