Method for heating a catalyst used in internal combustion engine with direct fuel injection

Abstract

A method for heating a catalytic converter in internal combustion engines is introduced wherein: an index for the temperature of the catalytic converter is formed; below a predetermined temperature of the catalytic converter, a first heating measure takes place wherein the temperature of the exhaust gas is increased; and, above the predetermined temperature, alternatively or supplementary to the first heating measure, a second heating measure takes place wherein a reaction-capable mixture is supplied to the catalytic converter in addition to the exhaust gas and the reaction of this mixture releases heat in the catalytic converter.

1 . Method for heating up a catalytic converter in internal combustion engines, characterized in that: 
 an index for the temperature of the exhaust-gas system is formed;    a first heating measure takes place below a predetermined temperature of the exhaust-gas system at which the temperature of the exhaust gas is increased; and,    above a predetermined temperature, alternatively or supplementary to the first heating measure, a second heating measure takes place for which a reaction-capable mixture is supplied to the catalytic converter in addition to the exhaust gas and the reaction of this mixture releases heat in the catalytic converter.    
     
     
         2 . Method of  claim 1 , characterized in that, as a first measure, a deterioration of the efficiency of the engine combustion takes place via a change of the ignition angle.  
     
     
         3 . Method of  claim 1 , characterized in that, as a second measure for an engine having gasoline-direct injection, a fuel after-injection takes place after the combustion.  
     
     
         4 . Method of  claim 3 , characterized in that the after-injection is combined with stratified operation.  
     
     
         5 . Method of  claim 4 , characterized in that the air quantity, which is inducted by the internal combustion engine, is throttled to the extent that the needed heat flow is achieved for a requested higher temperature.  
     
     
         6 . Method of  claim 1 , characterized in that an exhaust-gas composition is adjusted for a heating of an NOx-storage catalytic converter in homogeneous operation, the exhaust-gas composition deviating from the stoichiometric exhaust-gas composition.  
     
     
         7 . Electronic control arrangement for carrying out the method of the  claims 1  to  6 .