Patent ID: 7644790

Claim:
A method for controlling a hybrid drive mechanism having a variable ratio transmission ( 5 ), an electric machine ( 4 ) operable as a motor and connected directly to a transmission input shaft ( 5 a ) of the transmission ( 5 ) for transmitting at least one of positive torque and negative torque to the transmission ( 5 ), and an internal combustion engine ( 1 ) connectable to the transmission input shaft ( 5 a ) by a clutch ( 2 ), comprising the steps of: at an initial time (t 0 ), setting the internal combustion engine ( 1 ) in an off state and the transmission ( 5 ) in a neutral state, and engaging the clutch ( 2 ) to connect the electric machine ( 4 ) to the internal combustion engine ( 1 ), in a first interval between initial time (t 0 ) and a first time (t 1 ), driving the internal combustion engine ( 1 ) with the electric machine ( 4 ) to increase the rotational speed of the internal combustion engine ( 1 ) to an internal combustion engine idle speed, at first time (t 1 ), turning on the internal combustion engine ( 1 ) and disengaging the clutch ( 2 ), in a second interval between first time (t 1 ) and a second time (t 2 ), decreasing the rotational speed of the electric machine ( 4 ), and selecting a gear ratio of the transmission ( 5 ), at second time (t 2 ), engaging the transmission ( 5 ) in the selected gear ratio, in a third interval between second time (t 2 ) and a third time (t 4 ), controlling the rotational speed of the electric machine ( 4 ) and thereby of the transmission input shaft ( 5 a ) according to a desired rotational speed of an transmission output shaft ( 5 b ), at the third time (t 4 ), detecting that a desired rotational speed of the transmission output shaft ( 5 b ) is approaching a maximum speed attainable by the electric machine ( 4 ) with the transmission ( 5 ) in the selected gear ratio, in a fourth interval between the third time (t 4 ) and a fourth time (t 5 ), controlling the rotational speed of the internal combustion engine ( 1 ) to be approximately the rotational speed of the electric machine ( 4 ), and engaging the clutch ( 2 ) so that the internal combustion engine ( 1 ) drives the transmission input shaft ( 5 a ), and in a fifth interval after fourth time (t 5 ), controlling the rotational speed of the internal combustion engine ( 1 ) and thereby of the transmission input shaft ( 5 a ) according to a desired rotational speed of the transmission output shaft ( 5 b ).