Patent ID: 8123655

Claim:
A power output apparatus that outputs power to a driveshaft, said power output apparatus comprising: a power generation structure that receives a supply of fuel to generate electric power; a motor that inputs and outputs power; a change speed transmission mechanism that is arranged between a rotating shaft of the motor and the driveshaft to convert an input power with a changeover of a gear ratio and to transmit the converted power; an accumulator unit that transmits electric power to and from the power generation structure and the motor; a charge-discharge state detection unit that detects a charge-discharge state of the accumulator unit; a power demand setting unit that sets a power demand required for the driveshaft; and a control module that controls the power generation structure, the motor, and the change speed transmission mechanism during a changeover of the gear ratio of the change speed transmission mechanism while outputting a power substantially equivalent to the power demand to the driveshaft and to vary a changeover state of the gear ratio of the change speed transmission mechanism with a view to, in the event of a deviation of the detected charge-discharge state of the accumulator unit out of an allowable control range set as an allowed charge state range of the accumulator unit, making the charge-discharge state of the accumulator unit enter the allowable control range.