Vehicle control device and vehicle control method

A vehicle control method which is executed by a computer, the vehicle control method comprising:

• specifying a road gradient of a section from a position of a vehicle to a position ahead by a predetermined distance from the position of the vehicle on a road on which the vehicle travels;
• calculating a balance gradient that is a gradient at which a propulsive force of the vehicle and a resistance force applied to the vehicle are balanced when the vehicle travels in a gear-in coasting state in which an engine is connected to a gear and the vehicle travels without supplying fuel to the engine, the balance gradient being calculated in a case where a traveling state of the vehicle is a neutral coasting state that is a state of traveling without connecting the engine to the gear;
• and
• switching, based on the calculated balance gradient and the specified road gradient, the traveling state of the vehicle from the neutral coasting state to the gear-in coasting state in a case where the traveling state of the vehicle is the neutral coasting state;
• determining whether an end condition of the gear-in coasting state is satisfied after a predetermined time has elapsed since the traveling state of the vehicle is switched to the gear-in coasting state;
• and ending the gear-in coasting state when determining that the end condition is satisfied.

A vehicle control device comprising:

• a road gradient specifying unit configured to specify a road gradient of a section from a position of a vehicle to a position ahead by a predetermined distance from the position of the vehicle on a road on which the vehicle travels;
• a balance gradient calculation unit configured to calculate a balance gradient that is a gradient at which a propulsive force of the vehicle and a resistance force applied to the vehicle are balanced when the vehicle travels in a gear-in coasting state in which an engine is connected to a gear and the vehicle travels without supplying fuel to the engine, the balance gradient being calculated in a case where a traveling state of the vehicle is a neutral coasting state that is a state of traveling without connecting the engine to the gear;
• and
• a traveling control unit configured to:
• switch, based on the calculated balance gradient and the specified road gradient, the traveling state of the vehicle from the neutral coasting state to the gear-in coasting state in a case where the traveling state of the vehicle is the neutral coasting state;
• determine whether an end condition of the gear-in coasting state is satisfied after a predetermined time has elapsed since the traveling state of the vehicle is switched to the gear-in coasting state;
• and end the gear-in coasting state when determining that the end condition is satisfied.