To prevent the drop of torque of a driving shaft at a changing time of a change gear ratio in a hybrid automobile where an output shaft of an engine, a rotary shaft of a motor MG1, and a driving shaft are interconnected via a planetary gear, and a rotary shaft of motor MG2 is connected to the driving shaft via a transmission capable of changing the change gear ratio.
When a change of the change gear ratio is requested, an operation point of the engine is changed to an operation point D2 where a rotation speed is higher by rotation deviation ΔN than that at an operation point D1 allowing an effective operation on an output constant curve, and then the change gear ratio is changed. During the change, loss consumed by the transmission is compensated by an output from the engine. When the operation point is changed to the operation point D2 where the rotation speed is higher than that at the operation point D1 allowing effective operation, an output range in which an output can be outputted from the engine can be enlarged from the operation point. Therefore, the drop of the torque at a speed changing time can be certainly prevented.
UECHI KENSUKE
TAGA YUTAKA
YAMANAKA AKIHIRO
HOTTA MAKOTO
