Method of determining the amount of particulate accumulated in a particulate filter

A method of determining the amount of particulate (mS) accumulated in a particulate filter (9), comprising the steps of:

• determining at least one of the variation in spatial distribution of the particulate in said particulate filter (9) and the variation in the physical-chemical properties of the particulate as a function of engine operating conditions and past particulate accumulation in said partical filter (9);
• determining a number of reference values (βMAP) of a parameter (β) defining a relationship between the amount of particulate (mS) accumulated in said particulate filter (9) and the pressure drop (ΔPDPF) across the particulate filter (9), each of said reference values (βMAP) relating to a respective steady engine operating condition corresponding to a particular steady particulate accumulation condition in the particulate filter (9);
• determining an operating value (βMOD) of said parameter (β) relative to the current engine operating condition as a function of the reference value (βMAP) of said parameter (β) relative to the same engine operating condition, and of past particulate accumulation in said particulate filter (9);
• and
• determining the amount of particulate (mS) accumulated in said particulate filter (9) in the current engine operating condition as a function of the operating value (βMOD) of said parameter (β) calculated for said current engine operating condition.

A method of determining the amount of particulate (mS) accumulated in a particulate filter (9), comprising the steps of:

• determining the at least one of the variation in spatial distribution of the particulate in said particulate filter (9) and the variation in the phyaical-chemical properties of the particulate as a function of the engine operating conditions and past particulate accumulation in said particulate filter (9);
• determining an offset Δm after a certain amount of time after key-on, according to the following equation:
• Δm=mS—CORR—ECU−mS
• where:
• mS—CORR—ECU is the value of mS—CORR stored in the electronic control unit at the previous key-off;
• mS is the value of particulate accumulated in a particulate filter estimated without considering at least one of the variation in spatial distribution of the particulate in said particulate filter (9) and the variation in the physical-chemical properties of the particulate due to prolonged vehicle disuse (“parking” effect).

A method of determining the amount of particulate (mS) accumulated in a particulate filter (9), comprising the step of:

• determining the at least one of the variation in spatial distribution of the particulate in said particulate filter (9) and the variation in the phyaical-chemical properties of the particulate as a function of the engine operating conditions and past particulate accumulation in said particulate filter (9);
• determining an offset Δm after a partial regeneration (e.g. NOx-based spontaneous regeneration), according to the following equation:
• Δm=mS—CORR−mS
• where:
• mS—CORR is the value of particulate accumulated in a particulate filter before a partial regeneration (e.g. NOx-based spontaneous regeneration), decremented at every time step, during said partial regeneration state, with an experimentally estimated instantaneous value of particulate regenerated mNOx (a function of the engine operating conditions).
• mS is the value of particulate accumulated in a particulate filter estimated without considering at least one of the variation in spatial distribution of the particulate in said particulate filter (9) and the variation in the physical-chemical properties of the particulate due to partial regeneration (e.g. NOx-based spontaneous regeneration).