Deere & Company
Method for operating an internal combustion engine with an exhaust gas aftertreatment device

Abstract:

A method for operating an internal combustion engine with an exhaust gas aftertreatment device has a control system that determines a vector field of corresponding engine operating points (n.sub.Eng.sup.i, M.sub.Eng.sup.i) depending on a predetermined reducing agent-fuel consumption weighting q.sub.FD to be maintained during the operation of the internal combustion engine in order to derive a specific DEF-fuel consumption BSFC.sup.i for each of the engine operating points (n.sub.Eng.sup.i, M.sub.Eng.sup.i). The control system selects the element i.sup.Set from the identified vector field to which a minimum specific DEF-fuel consumption BSFC.sup.Set corresponds as the setpoint engine operating point (n.sub.Eng.sup.Set, M.sub.Eng.sup.Set), wherein the control system specifies a setpoint engine speed n.sub.Eng.sup.Set according to the selected element i.sup.Set and specifies therefrom a setpoint gear ratio r.sup.Set, taking into account a current gearbox output speed n.sub.out.