Patent ID: 8241174

Claim:
A method for controlling a torque output from a motor vehicle drive train and into a transmission in preparation for a gear shift operation of the transmission, the motor vehicle drive train including an internal combustion engine ( 2 ), an electric motor/generator ( 3 ) and a summarizing gear ( 5 / 15 ), a crankshaft ( 9 ) of the internal combustion engine ( 2 ) being releasably connected to a lock-up clutch ( 12 ) and fixedly connected to a first input element ( 6 ) of the summarizing gear ( 5 , 15 ), a rotor ( 10 ) of the electric motor/generator ( 3 ) being releasably connected to the lock-up clutch ( 12 ) and fixedly connected to a second input element ( 7 ) of the summarizing gear ( 5 , 15 ), the internal combustion engine and the electric motor/generator being inter-coupled to each other via both the summarizing gear ( 5 , 15 ) and the lock-up clutch, the summarizing gear ( 5 , 15 ) comprising the first input element ( 6 ), the second input element ( 7 ), and an output element ( 8 ), the output element ( 8 ) being fixed to an input shaft ( 11 ) of the transmission ( 4 ), and the lock-up clutch ( 12 ) being arranged between the first and the second input elements ( 6 , 7 ) of the summarizing gear ( 5 , 15 ), the method comprising the steps of: initiating a torque reduction process (t= 0 ) with the lock-up clutch ( 12 ) being at least partially engaged at the initiation of the torque reduction process (t= 0 ); determining a ratio (M_EM_ist/M_VM_ist) of an initial torque of the electric motor/generator (M_EM_ist) to an initial torque of the internal combustion engine (M_VM_ist); reducing a torque (M_VM) of the internal combustion engine ( 2 ) based on a previously defined time curve (M_VM_soll=f(t)); reducing a transmissible torque (M_K) of the lock-up clutch ( 12 ) proportionally to a rate of reduction of torque (M_VM_soll) in the internal combustion engine ( 2 ) until the lock -up clutch ( 12 ) is completely disengaged; and reducing an absolute value of a torque (M_EM_soll) of the electric motor/generator ( 3 ) proportionally to the rate of reduction of torque (M_VM_soll) in the internal combustion engine ( 2 ), such that the ratio of the torque of the electric motor/generator to the torque of the internal combustion engine is held substantially constant.