Patent ID: 8775043

Claim:
A control method for a hybrid vehicle in which the hybrid vehicle includes an internal-combustion engine, a traction motor that electrically drives the hybrid vehicle, a continuous variable transmission provided between an output shaft of the internal-combustion engine and an axle of first drive wheels, a clutch provided between the output shaft of the internal-combustion engine and an input shaft of the continuous variable transmission, and a starter motor connected coaxially to the output shaft of the internal combustion engine, the method comprising the steps of: determining whether there is a need to add a traction force of the internal-combustion engine from a state where the vehicle is driven by the traction motor alone; starting the internal-combustion engine using a torque of the starter motor in a state where the clutch is disengaged when it is determined that there is a need to add the traction force of the internal-combustion engine, subsequently increasing a torque of the internal-combustion engine, and controlling a speed ratio of the continuous variable transmission so that a rotation speed of the input shaft of the continuous variable transmission achieves a target speed for starting clutch engagement; detecting a rotation speed of the output shaft of the internal-combustion engine; detecting the rotation speed of the input shaft of the continuous variable transmission; applying a negative torque of the starter motor to the internal-combustion engine to suppress a climb in the speed of the internal-combustion engine and switching the controlling the speed ratio of the continuous variable transmission from the achieving the target speed to increasing the rotation speed of the input shaft of the continuous variable transmission beyond the target speed, when the detected rotation speed of the output shaft of the internal-combustion engine becomes as high as or higher than the detected rotation speed of the input shaft of the continuous variable transmission; and operating the clutch to be engaged.