Abstract: An exhaust-gas cleaning device for an engine comprises an HC-adsorbing catalytic converter disposed in an exhaust passage, the HC-adsorbing catalytic converter including an HC-adsorbing material which adsorbs HC contained in exhaust gas at low temperatures and releases adsorbed HC as the temperature increases, an oxygen storage material which occludes oxygen when the concentration of oxygen in the exhaust gas is high and releases occluded oxygen as the oxygen concentration drops, and a three-way catalys metal layer which oxidizes HC released from the HC-adsorbing material, and an oxygen concentration controller which controls the oxygen concentration in the exhaust gas on the upstream side of the HC-adsorbing catalytic converter in such a manner that oxygen is released from the oxygen storage material when the engine is in an operating condition in which HC is released from the HC-adsorbing material.

Abstract: An exhaust gas purifying device of the present invention comprises NOx trap catalyst including NOx trap material, catalytic metal and O2 storage material, NOx sensor, section for releasing NOx when NOx absorbed amount of the NOx trap catalyst reaches a specified amount, section for determining diagnosis conditions of the NOx trap catalyst, section for detecting termination of O2 release from the O2 storage material, and section for diagnosing O2 storage capacity according to output value (NO1) of the NOx sensor during a term from beginning of the oxygen concentration lowering by the NOx release section until termination of the O2 release and for diagnosing NOx reduction capacity of the catalytic metal according to output value (NO2) of the NOx sensor after termination of O2 release, wherein a speed of lowering oxygen concentration during the diagnosis is set so as to be slower than that during non-diagnosis.

Abstract: An exhaust gas purifying device of the present invention comprises NOx trap catalyst including NOx trap material, catalytic metal and O2 storage material, NOx sensor, section for releasing NOx when NOx absorbed amount of the NOx trap catalyst reaches a specified amount, section for determining diagnosis conditions of the NOx trap catalyst, section for detecting termination of O2 release from the O2 storage material, and section for diagnosing O2 storage capacity according to output value (NO1) of the NOx sensor during a term from beginning of the oxygen concentration lowering by the NOx release section until termination of the O2 release and for diagnosing NOx reduction capacity of the catalytic metal according to output value (NO2) of the NOx sensor after termination of O2 release, wherein a speed of lowering oxygen concentration during the diagnosis is set so as to be slower than that during non-diagnosis.

Abstract: In steps S25 to S42, in order to activate an inactive catalyst earlier, the air-fuel ratio in a combustion chamber is set to be &lgr;≈1 during a period T1 after engine start until catalyst light-off at around 50% HC purifying ratio immediately after the HC purifying ratio begins to rapidly rise, before the catalyst warms up, divisional injection is made at least during the period T1 required until light-off is reached, and a swirl is weakened during the period T1 compared to a latter period which follows this period T1. The divisional injection is made and the swirl is strengthened even during the latter period.

Abstract: An exhaust-gas cleaning device for an engine comprises an HC-adsorbing catalytic converter disposed in an exhaust passage, the HC-adsorbing catalytic converter including an HC-adsorbing material which adsorbs HC contained in exhaust gas at low temperatures and releases adsorbed HC as the temperature increases, an oxygen storage material which occludes oxygen when the concentration of oxygen in the exhaust gas is high and releases occluded oxygen as the oxygen concentration drops, and a three-way catalys metal layer which oxidizes HC released from the HC-adsorbing material, and an oxygen concentration controller which controls the oxygen concentration in the exhaust gas on the upstream side of the HC-adsorbing catalytic converter in such a manner that oxygen is released from the oxygen storage material when the engine is in an operating condition in which HC is released from the HC-adsorbing material.

Abstract: An exhaust-gas cleaning device comprises an absorption quantity detector (22) for determining the first and second amounts of NOx and oxygen absorbed by a NOx-absorbing material and an oxygen-absorbing material during first and second reference times based on sensing signals fed from an oxygen concentration detector (11), a NOx quantity estimator (23) for obtaining first and second estimated values of the amount of NOx absorbed by the NOx-absorbing material during the first and second reference times in accordance with engine operating condition, and a deterioration detector (24) for making a judgment on deterioration of the NOx-absorbing material based on the first and second amounts of absorption of NOx and oxygen determined by the absorption quantity detector (22) and the first and second estimated values of the amount of NOx obtained by the NOx quantity estimator (23).

Abstract: In steps S25 to S42, in order to activate an inactive catalyst earlier, the air-fuel ratio in a combustion chamber is set to be &lgr;≈1 during a period T1 after engine start until catalyst light-off at around 50% HC purifying ratio immediately after the HC purifying ratio begins to rapidly rise, before the catalyst warms up, divisional injection is made at least during the period T1 required until light-off is reached, and a swirl is weakened during the period T1 compared to a latter period which follows this period T1. The divisional injection is made and the swirl is strengthened even during the latter period.

Abstract: An exhaust-gas cleaning device comprises an absorption quantity detector (22) for determining the first and second amounts of NOx and oxygen absorbed by a NOx-absorbing material and an oxygen-absorbing material during first and second reference times based on sensing signals fed from an oxygen concentration detector (11), a NOx quantity estimator (23) for obtaining first and second estimated values of the amount of NOx absorbed by the NOx-absorbing material during the first and second reference times in accordance with engine operating condition, and a deterioration detector (24) for making a judgment on deterioration of the NOx-absorbing material based on the first and second amounts of absorption of NOx and oxygen determined by the absorption quantity detector (22) and the first and second estimated values of the amount of NOx obtained by the NOx quantity estimator (23).

Abstract: An engine control device, which is adapted for an engine provided with an NOx-absorbing material arranged in an exhaust passage for absorbing NOx in an oxygen-rich atmosphere, and releasing NOx and absorbing sulfur content when the oxygen concentration drops, includes a discriminator for judging whether the amount of sulfur absorbed by the NOx-absorbing material has reached a prescribed quantity, and a reductant concentration controller which increases the temperature of the NOx-absorbing material by decreasing a quantity related to EGR ratio for desulfurizing the NOx-absorbing material based on the result of judgment made by the discriminator. When the quantity related to the EGR ratio is decreased, the temperature of exhaust gas increases. Consequently, the temperature of the NOx-absorbing material increases and the sulfur in the NOx-absorbing material is freed and released.

Abstract: An engine control system for an engine equipped with a swirl control valve which is operative in operation modes different in fuel injection form according to engine operating conditions judges based on a change in an engine operating condition whether a mode shift to one operation mode to another is demanded and controls the swirl control valve so as to attain a target opening for the one engine operation mode while keeping a specific mode shift waiting until the swirl valve opening reaches a limit value permissible in one engine operation mode into which the specific mode shift is made when the swirl control valve is judged to be out of the limit value.

Abstract: An engine control system for a direct injection-spark ignition type of engine determines a target load based on an engine speed and an accelerator pedal travel, determines target air-to-fuel ratio based on an amount of intake air and the target engine load, and determines an amount of fuel injection based on the target air-to-fuel ratio, so as thereby to control engine output torque balancing the target engine load even during a transitional operating state.

Abstract: An exhaust gas purifying system includes an exhaust gas purifying catalyst having a nitrogen oxide absorbing material which is installed in an exhaust line of an engine and performs split fuel injection to inject fuel directly into each combustion chamber partly during a suction stroke and partly during a compression stroke to provide and supply an increased amount of carbon monoxide to the nitrogen oxide absorbing material so as thereby to desorb sulfur oxides from the nitrogen oxide absorbing material.

Abstract: A direct injection engine provided with an injector at a peripheral portion of a combustion chamber to inject at least at a latter stage of a compression stroke in at least in a low engine load and low engine speed condition, wherein a distance from the tip end of the injector to an opposite end the combustion chamber is determined greater than a traveling distance of an injected fuel for a time period from a start of a fuel injection at the latter stage of the compression stroke to the ignition timing, wherein; an ignition plug is arranged that an ignition gap is disposed within an injection area of the injector; and, wherein a distance from the tip end of the injector to the ignition gap is determined smaller than said traveling distance of the injected fuel. An ignitability and combustion stability can be improved to thereby improve a fuel consumption efficiency.