Patent ID: 7891347
Filing Date: 2011-02-22
Classification: F02D,Y02T

Abstract:
1. A method for operating an internal combustion engine comprising: providing an intake tract and an exhaust gas tract having an exhaust gas catalytic converter, the intake gas track being in communication with a combustion chamber of the internal combustion engine as a function of a position of gas intake valve and the exhaust gas tract being in communication with a combustion chamber of the internal combustion engine as a function of a gas discharge valve; providing an intake valve lift adjusting device that adjusts a valve lift of the gas intake valve; determining a first model value of the exhaust gas counter pressure upstream of the exhaust gas catalytic converter that is representative of the exhaust gas counter pressure in a current operating mode of the internal combustion engine assuming a low valve lift, as a function of at least one operating variable of the internal combustion engine; determining a second model value of the exhaust gas counter pressure upstream of the exhaust gas catalytic converter that is representative of the exhaust gas counter pressure in a current operating mode of the internal combustion engine assuming a high valve lift, as a function of the at least one operating variable of the internal combustion engine; determining a curve of a filtered model value of the exhaust gas counter pressure as a function of: the curve of the filtered model value being determined essentially during the adjustment of the valve lift from the low valve lift to the high valve lift or from the high valve lift to the low valve lift; and allocating a curve of a current value of the exhaust gas counter pressure to the curve of the filtered model value of the exhaust gas counter pressure during the adjustment and/or shortly before the adjustment of the valve lift.