Exhaust gas cleaning system for diesel engine

An exhaust gas cleaning system for a diesel engine (2), comprising:

• a filter (4) disposed in an exhaust system of the diesel engine (2) in order to trap any particulate matter included in exhaust gases;
• first and second pressure sensors (21, 22) disposed at upstream and downstream sides, respectively, of said filter;
• and
• differential pressure computing means (50b) for computing, on the basis of pressures (P1, P2) detected by said first and second pressure sensors (21, 22), a differential pressure (P12) existing across said filter, the differential pressure across said filter computed by said differential pressure computing means being used for the system to judge whether said filter needs to be regenerated by burning off the particulate matter deposited therein;
• wherein said exhaust gas cleaning system includes
• correction data computing means (50a) by which, each time a key switch (20) for starting the diesel engine is turned on and before the diesel engine is started, any differences of the pressures detected by said first and second pressure sensors, with respect to a predetermined reference pressure value (Pref), are computed to obtain first and second correction values (ΔP1, ΔP2), and
• correction data storage means into which the first and second correction values computed by said correction data computing means are stored;
• and
• said differential pressure computing means (50b) is adapted to use, in addition to the pressure detection results of said first and second pressure sensors, the first and second correction values stored in the correction data storage means, to compute the differential pressure across said filter.