Hybrid vehicle, control method of hybrid vehicle, and power output apparatus

A power output apparatus that outputs power to a drive shaft, said power output apparatus comprising:

• an internal combustion engine;
• an electric power-mechanical power input output mechanism that is connected to an output shaft of the internal combustion engine and to the drive shaft and inputs and outputs power from and to the output shaft and the drive shaft through input and output of electric power and mechanical power;
• a motor that inputs and outputs power from and to the drive shaft;
• an accumulator unit that transmits electric power to and from the electric power-mechanical power input output mechanism and the motor;
• a power demand setting module that sets a power demand required for the drive shaft;
• a rotation speed measurement module that measures rotation speed of the drive shaft;
• a lower rotation speed limit setting module that sets a lower rotation speed limit, which represents a minimum allowable rotation speed of the internal combustion engine, corresponding to the measured rotation speed;
• and
• a control module that controls the internal combustion engine, the electric power-mechanical power input output mechanism, and the motor to drive the internal combustion engine at a rotation speed of not lower than the set lower rotation speed limit and to output a power corresponding to the set power demand to the drive shaft.

A control method of a hybrid vehicle, said hybrid vehicle comprising:

• an internal combustion engine;
• an electric power-mechanical power input output mechanism that is connected to an output shaft of the internal combustion engine and to a drive shaft linked with one axle of said hybrid vehicle and inputs and outputs power from and to the output shaft and the drive shaft through input and output of electric power and mechanical power;
• a motor that inputs and outputs power from and to either of the one axle and the other axle, which is different from the one axle;
• and an accumulator unit that transmits electric power to and from the electric power-mechanical power input output mechanism and the motor,
• said control method comprising the steps of:
• (a) setting a drive power demand required for a drive of said hybrid vehicle;
• (b) setting a lower rotation speed limit, which represents a minimum allowable rotation speed of the internal combustion engine, corresponding to a measured vehicle speed;
• and
• (c) controlling the internal combustion engine, the electric power-mechanical power input output mechanism, and the motor to drive the internal combustion engine at a rotation speed of not lower than the set lower rotation speed limit and to drive said hybrid vehicle with a power corresponding to the set drive power demand.