EXHAUST PURIFICATION SYSTEM FOR CONSTRUCTION MACHINE

摘要

An exhaust purification system for a construction machine, in which a filter is regenerated before a large amount of PM is accumulated on the filter, which avoids a reduction in an output caused by a rise in the pressure of exhaust gas immediately before the regeneration, and which reduces the possibility of an abnormal rise in the temperature inside the filter caused by burning of PM involved in regeneration and also reduces the possibility of melting of the filter due to the abnormal temperature rise. An automatic regeneration switch (38b) is previously set to an ON position, and a key switch (5) is set to an OFF position after a gate lock lever (22) is raised to a second position (B). Then, when the value (pressure difference across a filter (32)) detected by a pressure difference detection device (36) is higher than a second predetermined pressure (P2), the controller (4) controls the speed of an engine to a predetermined speed (Na) and then automatically starts forced regeneration to burn and remove PM. When the value detected by the pressure difference detection device (36) becomes lower than a first predetermined pressure (P1), the controller (4) automatically ends the regeneration and stops the engine (1).