Patent ID: 7794356

Claim:
A power output apparatus of outputting power to a driveshaft, the power output apparatus comprising: an internal combustion engine; a generator configured to input and output power; a three shaft-type power input output structure connected to three shafts, an output shaft of the internal combustion engine, a rotating shaft of the generator, and a power shaft as a third shaft, and configured to input and output power from and to a residual shaft based on powers input from and output to any two shafts among the three shafts; an accumulator configured to transmit electric power to and from the generator; a transmission configured to connect the power shaft with the driveshaft for transmission of power between the power shaft and the driveshaft with a change of speed and to disconnect the power shaft from the driveshaft in a neutral state; a driveshaft rotation speed detector configured to detect a driveshaft rotation speed representing a rotation speed of the driveshaft; and a controller configured, in a neutral in-range status where the detected driveshaft rotation speed is within a preset range including a value 0 in the neutral state of the transmission during operation of the internal combustion engine, to control the internal combustion engine and the generator to make a rotation speed of the power shaft equal to 0 and to enable self-sustained operation of the internal combustion engine, and in a neutral out-of-range status where the detected driveshaft rotation speed is out of the preset range in the neutral state of the transmission during operation of the internal combustion engine, to control the internal combustion engine and the generator to make the rotation speed of the power shaft substantially synchronous with an expected rotation speed of the power shaft, which is expected in release of the neutral state of the transmission, and to enable self-sustained operation of the internal combustion engine in a limit of an allowable rotation speed of the generator.