Patent ID: 7377344

Claim:
A hybrid drive system for a vehicle, the hybrid drive system comprising: an internal combustion engine; an electric machine operable as an electric motor and a generator; a transmission having a continuously variable ratio; a first clutch coupling the internal combustion engine with the electric machine; a second clutch coupling the electric machine with the transmission, which transmission is connectable to a drive shaft of the vehicle; an electric energy accumulator; a converter device for controlling energy flow between the electric machine and the electric energy accumulator; an electric control device adapted to control the internal combustion engine, the transmission, the converter device and the first and second clutches as a function of a charge state of the energy accumulator and a drive power demand of the vehicle, the control device further adapted to control a starting of the internal combustion engine, when the second clutch is at least partially closed, by closing the first clutch; wherein, during the starting of the internal combustion engine while driving the continuously variable ratio of the transmission is stepped down during the closing of the first clutch.