Vehicle with automatic engine stop/restart function and automatic engine stop/restart system and method for vehicle

An automatic engine stop/restart system for a vehicle, the system comprising:

• means for stopping an engine automatically upon satisfaction of an automatic engine stop condition;
• means for determining whether an oil pressure in an automatic transmission of the vehicle becomes lower than a predetermined value during an automatic stop of the engine;
• means for restarting the engine automatically upon satisfaction of an automatic engine restart condition, when the oil pressure in the automatic transmission is higher than or equal to the predetermine value;
• means for shifting the automatic transmission into a neutral state, when the oil pressure in the automatic transmission becomes lower than the predetermined value during the automatic stop of the engine;
• means for restarting the engine automatically while the automatic transmission is in the neutral state;
• and
• means for shifting the automatic transmission from the neutral state to a drive state after the oil pressure in the automatic transmission is increased to the predetermined value by an oil pump driven in synchronism with the engine.

An automatic engine stop/restart method for a vehicle, the method comprising:

• determining whether an oil pressure in an automatic transmission of the vehicle becomes lower than a predetermined value while an engine of the vehicle is in an automatic stop state;
• restarting the engine automatically from the automatic stop state upon satisfaction of an automatic engine restart condition, when the oil pressure in the automatic transmission is higher than or equal to the predetermined value;
• shifting the automatic transmission into a neutral state, when the oil pressure in the automatic transmission is lower than the predetermined value;
• restarting the engine automatically from the automatic stop state while the automatic transmission is in the neutral state;
• and
• shifting the automatic transmission from the neutral state to a drive state, after the oil pressure in the automatic transmission is increased to the predetermined value by an oil pump driven in synchronism with the engine.