Patent ID: 7267991

Claim:
Method for estimating sulfur content in fuel of an internal combustion engine ( 1 ) equipped with at least one cylinder ( 2 ) and at least one catalyser ( 11 ), said catalyser ( 11 ) being capable of storing a quantity of sulfur and NO x groups and being subjected to a regeneration process to remove NO x groups when efficiency (I) of the catalyser ( 11 ) falls outside an acceptable range, the method providing a determination of a percentage (S) of sulfur present in fuel supplied during a specific measurement time interval by dividing a quantity (SO xstored ) of sulfur stored in the catalyser ( 11 ) during the measurement time interval by a product of a fixed conversion constant (K SOx ) and a mass of fuel (m fuel ) supplied to the cylinder ( 2 ) in the measurement time interval, comprising the steps of estimating a first quantity (NO xstored ) of NO x groups stored by the catalyser ( 11 ) immediately before a regeneration process to remove NO x groups at a beginning of the measurement time interval, estimating a second quantity (NO xstored ) of NO x groups stored by the catalyser ( 11 ) immediately before a regeneration process to remove NO x groups at an end of the measurement time interval, and estimating said quantity (SO xstored ) of sulfur stored in the catalyser ( 11 ) during the measurement time interval from a difference between said first quantity (NO xstored ) of NO x groups and said second quantity (NO xstored ) of NO x groups, and obtaining each said quantity (NO xstored ) of NO x groups stored by the catalyser ( 11 ) by subtracting from a quantity (NO xtotal ) of NO x groups produced by the engine ( 1 ) a quantity (NO xloss ) of NO x groups not captured by the catalyser ( 11 ).