Drive system for a hybrid vehicle and method for operating said system

A method for operating a drive system for a hybrid vehicle, the drive system including, an internal combustion engine having an internal combustion engine shaft configured to output drive power in the direction of drivable wheels of the hybrid vehicle, a vehicle transmission having a transmission input shaft at a drive side, a transmission output shaft at an output side, and a transmission clutch configured to couple or decouple the transmission input shaft and the transmission output shaft, a centrifugal mass drive unit arranged between the internal combustion engine shaft and the transmission input shaft, an intermediate shaft, a first clutch configured to couple or decouple the internal combustion engine shaft to or from the intermediate shaft a second clutch configured to couple or decouple the intermediate shaft to or from the transmission input shaft, and an electric machine configured to transfer torque to the transmission input to drive the hybrid vehicle in a motor operating mode, the centrifugal mass drive unit having a rotary vibration reduction device having a reduction device drive-side input shaft and a reduction device output-side output shaft, the rotary vibration reduction device being configured to reduce rotary vibrations of the intermediate shaft, the rotary vibration reduction device is arranged entirely between the first clutch and the second clutch, and an electric control unit configured to control actuation of the first clutch, second clutch, transmission clutch and electric machine, comprising the acts of:

• determining whether the drive system is in an operating state in which at least one of the first clutch is opened and the internal combustion engine is deactivated;
• operating the electric machine with second clutch closed such that the centrifugal mass drive unit is accelerated to or maintained at a centrifugal mass starting rotational speed;
• receiving at the electric control unit a signal for active vehicle acceleration;
• determining from the signal for active vehicle acceleration a start-up of the internal combustion engine is needed;
• opening the second clutch with the electric control unit;
• after the second clutch is opened, closing the first clutch with the electric control unit such that angular momentum from the centrifugal mass drive unit rotates the internal combustion engine to an internal combustion engine starting rotational speed;
• and
• after reaching the internal combustion engine starting rotational speed, operating the internal combustion engine in a fired operating mode and accelerating the internal combustion engine to an internal combustion engine target rotational speed.