Patent ID: 8460625

Claim:
An exhaust gas purification apparatus for an engine, the apparatus comprising: a filter which is arranged in an exhaust passage of the engine and collects particulate matter contained in exhaust gas and in which active regeneration is performed to burn out the collected particulate matter by heating; an oxidation catalyst which is arranged upstream of the filter and which is used to heat the filter; and a regeneration control unit which performs regeneration of the filter by burning the particulate matters accumulated in the filter, wherein the control unit comprises an over-accumulation state determination unit and a switch, wherein the over-accumulation state determination unit determines that the particulate matter is over-accumulated in the filter in such a case that: the amount of the particulate matter accumulated in the filter becomes not less than a specified amount which is greater than a predetermined amount of a normal regeneration starting condition; the amount of the particulate matter accumulated in the filter is less than the specified amount and a specified time has passed since a last regeneration of the filter, the specified time being greater than a predetermined time of the normal regeneration starting condition; or the amount of the particulate matter accumulated in the filter is less than the specified amount and an amount of fuel supply reaches a specified supply amount which is greater than a predetermined supply amount of the normal regeneration starting condition, wherein the switch switches a regeneration temperature for regenerating the filter between a first regeneration temperature at which a normal regeneration is performed and a second regeneration temperature which is lower than the first regeneration temperature, and wherein the control unit is connectable to a command unit, in such a case that the over-accumulation state determination unit determines that the particular matter is over-accumulated in the filter, so that the switch is forcibly operated toward the second regeneration temperature.