1. Field of the Invention
The invention relates to a hybrid vehicle and a method for controlling the same and, more particularly, to a technique for controlling a heating apparatus that is loaded on a hybrid vehicle.
2. Description of Related Art
Japanese Patent Application Publication No. 2011-31704 (JP 2011-31704 A) discloses an air conditioning system for vehicles that is applied to hybrid vehicles. The hybrid vehicle includes an engine and a motor that generate a driving force for traveling, and a battery that supplies electric power to the motor. The air conditioning system has a vapor compression type refrigerant cycle, and hot water heating means. The vapor compression type refrigerant cycle has an electric compressor that compresses a refrigerant by using air conditioning electric power, and constitutes a heat pump cycle that heats blowing air which is blown into a vehicle cabin. The hot water heating means heats the blowing air by using a coolant of the engine as a heat source.
The engine is started (for HV traveling in which the engine is operated for traveling) when the remaining amount of the battery is below a margin expected level, at which a predetermined margin is expected with respect to an air conditioning difficulty level at which the supply of the air conditioning electric power is limited, during EV traveling in which the engine is stopped for motor-based traveling in the air conditioning system. In this manner, the temperature of the coolant at a time when the remaining amount of the battery is below the air conditioning difficulty level can be increased, and the heating can be continued without having to be paused even when the remaining amount of the battery declines (refer to Japanese Patent Application Publication No. 2011-31704 (JP 2011-31704 A)).
In recent years, hybrid vehicles whose batteries can be charged with electric power supply from outside the vehicles (hereinafter, referred to as “external electric power supply”) have been developed (hereinafter, the charging of the battery with the external electric power supply will be referred to as “external charging”). In the hybrid vehicles of the related art, the EV traveling and the HV traveling are repeated so as to maintain a estate of charge (SOC) of the battery within a predetermined range. Meanwhile, in the hybrid vehicles that allow the external charging, a charge depleting (CD) mode in which the SOC is consumed and a charge sustaining (CS) mode in which the SOC is maintained within a predetermined range are selectively applied in traveling. The EV traveling is switched to the HV traveling even in the CD mode when large traveling power is required, and the HV traveling is switched to the EV traveling even in the CS mode when the SOC rises within a predetermined range. In other words, the EV traveling and the HV traveling are possible in both the CD mode and the CS mode.
In the CS mode, the start/stop of the engine is appropriately performed so as to maintain the SOC within a predetermined range. In contrast, the chance of engine start is smaller in the CD mode in which the SOC is consumed than in the CS mode.