Abstract: A piston of a direct injection type diesel engine has a re-entrant type cavity, and a fuel injection nozzle with multiple nozzle holes is arranged on the center line thereof. The cavity has a lip portion, which is the portion thereof having the smallest diameter, positioned below a piston crown surface and a pocket portion formed above the lip portion. The pocket portion is positioned at a height to which a pilot injection injected prior to the top dead center under engine idling is directed, and the position of a wall surface is so set that a leading part of the injection spray does not collide strongly therewith. The fuel from the pilot injection temporarily stays in the pocket portion and moves into the cavity by means of a subsequent squish flow. Accordingly, an increase in unburned hydrocarbons is suppressed.

Abstract: A diesel engine 100 is provided with a common rail type fuel injection device. A controller 14 controls a common rail pressure and an engine control parameter other than the common rail pressure, respectively, to target values that are determined on the basis of the engine load. The controller 14 corrects the engine control parameter other than the common rail pressure when the common rail pressure does not coincide with the target common rail pressure in a transient state of the diesel engine, thereby preventing an air-fuel ratio in the combustion region from becoming lean.

Abstract: A diesel engine 100 is provided with a common rail type fuel injection device. A controller 14 controls a common rail pressure and an engine control parameter other than the common rail pressure, respectively, to target values that are determined on the basis of the engine load. The controller 14 corrects the engine control parameter other than the common rail pressure when the common rail pressure does not coincide with the target common rail pressure in a transient state of the diesel engine, thereby preventing an air-fuel ratio in the combustion region from becoming lean.

Abstract: A filter (14) traps particulate matter contained in the exhaust gas of a diesel engine (1). The filter (14) is regenerated by burning the trapped particulate matter through an operation to raise the exhaust gas temperature. An oxidation catalyst which promotes combustion of the particulate matter is coated onto the filter (14). The oxygen concentration of the exhaust gas upstream of the filter (14) and the oxygen concentration of the exhaust gas downstream of the filter (14) during the regeneration period are detected using universal exhaust gas oxygen sensors (17, 16). A controller (25) determines a substantial regeneration period on the basis of the difference between these oxygen concentrations, and by comparing a maximum value of the difference between the oxygen concentrations during the substantial regeneration period with a predetermined threshold, determines deterioration of the filter (14) with a high degree of precision.

Abstract: A filter (14) traps particulate matter contained in the exhaust gas of a diesel engine (1). The filter (14) is regenerated by burning the trapped particulate matter through an operation to raise the exhaust gas temperature. An oxidation catalyst which promotes combustion of the particulate matter is coated onto the filter (14). The oxygen concentration of the exhaust gas upstream of the filter (14) and the oxygen concentration of the exhaust gas downstream of the filter (14) during the regeneration period are detected using universal exhaust gas oxygen sensors (17, 16). A controller (25) determines a substantial regeneration period on the basis of the difference between these oxygen concentrations, and by comparing a maximum value of the difference between the oxygen concentrations during the substantial regeneration period with a predetermined threshold, determines deterioration of the filter (14) with a high degree of precision.