Patent ID: 7658064

Claim:
An exhaust gas purifying apparatus, comprising: a primary exhaust line exhausting an exhaust gas of a diesel engine; a primary diesel particulate filter provided in said primary exhaust line of the diesel engine, said primary diesel particulate filter purifying said exhaust gas by capturing a particulate matter in said primary exhaust line; a secondary exhaust line branched from said primary exhaust line from a branching point located at an upstream side of said primary diesel particulate filter; a secondary diesel particulate filter provided in said secondary exhaust line, said secondary diesel particulate filter having a soot storage capacity smaller than the soot storage capacity of said primary diesel particulate filter; a low pressure part provided in said secondary exhaust line at a downstream side of said secondary diesel particulate filter, said low pressure part providing a pressure lower than a pressure of said branching point; and a differential pressure measuring part measuring a differential pressure between an inlet and an outlet of said secondary diesel particulate filter, wherein said exhaust gas purifying apparatus estimates a concentration of said particulate matter in said exhaust gas based on said differential pressure and estimates the amount of particulate matter flowing into said primary diesel particulate filter based on said concentration of said particulate matter.