Abstract: An exhaust emission control device including a selective reduction catalyst; urea water as reducing agent being added in the pipe upstream of the reduction catalyst depurate NOx through reduction; an oxidation catalyst arranged in the pipe upstream of an added position of the urea water, the oxidation catalyst physically adsorbing NOx in the exhaust gas at a temperature lower than a lower active limit temperature of the reduction catalyst and discharging the adsorbed NOx at a temperature higher than a lower active limit temperature of the oxidation catalyst; and a fuel injection device for adding fuel into the exhaust gas upstream of the oxidation catalyst is disclosed. The start of the fuel addition by the fuel injection device is refrained until exhaust temperature on an inlet side of the reduction catalyst is increased to a preset temperature comparable with the lower active limit temperature of the oxidation catalyst.

Abstract: Disclosed is a control method for restoring temporary malfunction of an injector 8 for adding urea water 12 into exhaust gas due to adhesion of urea crystals. A passage is laid out such that the passage (suction line 14) for feed of the urea water 12 runs downward from above of and is connected to the injector 8. When the injector 8 is determined to be in malfunction, an operation of temporarily sucking back the urea water 12 in the passage (suction line 14) is interposed before the pump 13 is stopped; the pump 13 is restarted after lapse of a predetermined time to re-determine whether the injector 8 is in malfunction or not.

Abstract: Disclosed is a control method for restoring temporary malfunction of an injector 8 for adding urea water 12 into exhaust gas due to adhesion of urea crystals. A passage is laid out such that the passage (suction line 14) for feed of the urea water 12 runs downward from above of and is connected to the injector 8. When the injector 8 is determined to be in malfunction, an operation of temporarily sucking back the urea water 12 in the passage (suction line 14) is interposed before the pump 13 is stopped; the pump 13 is restarted after lapse of a predetermined time to re-determine whether the injector 8 is in malfunction or not.

Abstract: The invention has an object of exerting favorable NOx reducing effects even at an exhaust temperature lower than in the prior art without trouble, e.g., at startup after long-term engine rest and is directed to an exhaust emission control device wherein a selective reduction catalyst 5 capable of selectively reacting NOx with ammonia even in the presence of oxygen is incorporated in an exhaust pipe 4, urea water 6 as reducing agent being added in the pipe 4 upstream of the reduction catalyst 5 to depurate NOx through reduction.

Abstract: A NOx occluding reduction catalyst that occludes NOx is efficiently regenerated by carrying our post-injection of a necessary and sufficient quantity of fuel without diluting engine oil on the inner wall surface of a cylinder. A NOx absorbing agent and an active metal are carried on the NOx occluding reduction catalyst (16) provided in an exhaust gas passage (14) of an engine (11), and the fuel is supplied to the NOx occluding reduction catalyst (16) by adding the fuel to the exhaust gas in the exhaust gas passage (14) with a fuel adding means (17). The fuel adding means (17) is an accumulator fuel injector that carries out post-injection, following main injection into a cylinder (22) of the engine (11), at timing such that the fuel does not ignite in the cylinder (22). The post-injection with the accumulator fuel injector (17) is carried out in divided 3 to 20 times at the later period of the expansion stroke of the engine (11).

Abstract: Disclosed is a system for injecting fuel into a diesel engine exhaust pipe that prevents injected fuel from adhering to an exhaust pipe inner wall, adequately reduces and regenerates an exhaust gas purification catalyst, and remarkably increases fuel efficiency. This system includes a plurality of fuel injection nozzles, which are positioned in an exhaust pipe 10 of a diesel engine 1, injects fuel from the fuel injection nozzles, and reduces and regenerates the exhaust gas purification catalyst 11 that is installed in the exhaust pipe. The fuel injection nozzles are positioned so that injection axis lines 20a intersect with each other. It is preferred that the fuel injection nozzles be arranged in a circumferential direction of the exhaust pipe and positioned at substantially equal spacing intervals, and that the injection axis lines intersect at substantially one point. It is also preferred that the fuel injection nozzles be holed or slit fuel injection nozzles having one or two injection holes.

Abstract: A diesel engine includes a turbocharger, an intercooler, a particulate filtering unit, and an EGR cooler. EGR ratio of intake air, injection timing of an injection nozzle, and excess air ratio to fuel are controlled depending upon engine-operating load. Lean premixed compression ignition is performed at low engine load; low temperature combustion at low excess air ratio with high EGR ratio is performed at medium engine load; and normal EGR combustion is performed at high engine load.

Abstract: A diesel engine comprising a fuel injection device and a controller for controlling the fuel injection device in accordance with an operating condition of the engine. The fuel injection device effects a preliminary injection for injecting fuel into a cylinder during a period from the initial part of an intake stroke to the middle part of a compression stroke and a main injection for injecting fuel into a combustion chamber in the vicinity of a top dead center of the compression stroke, whereby lean mixture is formed and a maximum combustion temperature in the combustion chamber is decreased to suppress generation of NOx and to reduce emission of black smoke.