Abstract: Provided is a method of diagnosing regeneration failure of an exhaust emission control device including filter regenerating means for forcibly heating a particulate filter 13 so as to burn off captured particulates. An exhaust flow rate to the particulate filter 13 and a differential pressure between entry and exit sides of the particulate filter 13 are obtained to calculate a gradient of change in the differential pressure relative to change in the exhaust flow rate. The calculated gradient is compared with a predetermined reference gradient to diagnose the particulate filter 13 as having regeneration failure when the calculated gradient exceeds the reference gradient.

Abstract: A controller is constructed such that fuel addition by a fuel injection device is automatically conducted when a predetermined time has passed with a diesel engine being in an idling state, and without a regeneration button being manually operated under a condition of a particulate deposition amount being estimated by the controller on the basis of a pressure signal from a pressure sensor to be within a manual regeneration range over said automatic regeneration range.

Abstract: Provided is a method of diagnosing regeneration failure of an exhaust emission control device including filter regenerating means for forcibly heating a particulate filter 13 so as to burn off captured particulates. An exhaust flow rate to the particulate filter 13 and a differential pressure between entry and exit sides of the particulate filter 13 are obtained to calculate a gradient of change in the differential pressure relative to change in the exhaust flow rate. The calculated gradient is compared with a predetermined reference gradient to diagnose the particulate filter 13 as having regeneration failure when the calculated gradient exceeds the reference gradient.

Abstract: The invention has its object to provide an exhaust emission control device with realized lessening of both particulates and NOx which can always ensure high NOx reduction ratio irrespective of operation conditions. The exhaust emission control device has a selective reduction catalyst 5 as NOx lessening catalyst incorporated in an exhaust pipe 4 and having a property of capable of selectively reacting NOx with ammonia even in the presence of oxygen, and a particulate filter 13 arranged upstream of the catalyst. A burner 14 for injection, ignition and combustion of a proper amount of fuel is arranged in front of the particulate filter 13, and an oxidation catalyst 15 is interposed between the particulate filter 13 and the selective reduction catalyst 5 so as to conduct oxidation treatment of unburned HC in exhaust gas 3 and so as to facilitate oxidation reaction of NO in the exhaust gas 3 into NO2.

Abstract: The invention has its object to automatically conduct forced regeneration of a particulate filter 6 even if a driver forgets to conduct a manual operation under operation conditions met for the manual operation. A controller 9 (deposition amount estimating means) is constructed such that fuel addition by a fuel injection device 10 (fuel addition means) is automatically conducted when a predetermined time has passed with the diesel engine 1 being in idling state and without a regeneration button 15 (operation means) being manually operated under condition of a particulate deposition amount being estimated by the controller 9 on the basis of a pressure signal 8a from a pressure sensor 8 (deposition amount estimating means) to be within a manual regeneration range over an automatic regeneration range.