Abstract: There is provided an exhaust emission control apparatus for an internal combustion engine which can reduce the emission of toxic substances and quickly activate a catalyst. An exhaust flow control means suppresses the flow of exhaust in an exhaust system when the engine is started. An operative state detecting means detects whether or not the period of time elapsed after a vehicle starts accelerating from standstill is equal to or shorter than a predetermined period of time. While the operative state detecting means detects that the period of time elapsed after the vehicle starts accelerating from standstill is equal to or shorter than the predetermined period of time, an exhaust flow control limiting means stops or reduces the suppression of exhaust flow by the exhaust flow control device.

Abstract: When a NOx-releasing unit is operated to change an air-fuel ratio to a rich side to thereby establish a low-oxygen-concentration atmosphere of an exhaust gas such that NOx is released from a NOx catalyst, a reducer-supplying unit additionally supplies a reducer during an operating period of the NOx-releasing unit for reducing NOx released into an exhaust path such that release of NOx balances with reduction of NOx, thereby reducing NOx released from the NOx catalyst and thus suppressing worsening of exhaust gas performance.

Abstract: A catalyst deterioration detecting apparatus aims at accurately determining whether or not a catalyst deteriorates even if a strict standard for catalyst deterioration is established. The catalyst deterioration detecting apparatus includes catalyst temperature sensing means for obtaining temperature of a catalyst, including ceria (CeO2) serving as an oxygen storage agent, and deterioration detecting means for detecting a degree of deterioration of the catalyst if the temperature is obtained by the catalyst temperature sensing means is equal to or higher than an activation temperature at which the catalyst is activated and is in a particular temperature range causing NOX conversion efficiency of the catalyst to decrease.

Abstract: At the start of operation of an internal-combustion engine (S10,S12,S14), an exhaust flow is restrained (to raise the exhaust pressure) (S18), secondary air is supplied (S20), and the combustion air-fuel ratio (A/F) is set within the range of rich air-fuel ratios (S16, S22).

Abstract: When an internal combustion engine is in a cold state (S12), fuel is injected during compression stroke with burn air/fuel ratio controlled so as to produce a slight lean air/fuel mixture equivalent to or slightly leaner than a stoichiometric air/fuel mixture (compression S/L operation) (S14), and also exhaust gas flow is restrained (S16).

Abstract: When a NOx-releasing unit is operated to change an air-fuel ratio to a rich side to thereby establish a low-oxygen-concentration atmosphere of an exhaust gas such that NOx is released from a NOx catalyst, a reducer-supplying unit 33 additionally supplies a reducer during an operating period of the NOx-releasing unit for reducing NOx released into an exhaust path such that release of NOx balances with reduction of NOx, thereby reducing NOx released from the NOx catalyst and thus suppressing worsening of exhaust gas performance.

Abstract: An exhaust passage (20) of an internal-combustion engine (1) is provided with an exhaust emission control unit (40) capable of reducing harmful substances in exhaust gas under a given exhaust pressure condition and an exhaust sensor (22) for detecting the concentration of a specific exhaust component (H2, O2) in the exhaust gas, and a performance lowering identifying unit identifies lowering of the performance of the exhaust emission control (40) by detecting a failure to fulfill the given exhaust pressure condition in accordance with the output of the exhaust sensor.

Abstract: A catalyst deterioration suppressing apparatus and method stops supply of fuel when an engine is decelerating, and prohibits the supply of fuel from being stopped when the catalyst temperature is equal to or higher than a predetermined temperature when the engine is decelerating. When the supply of fuel is prohibited from being stopped, the air-fuel ratio is prohibited from being feedback-controlled. As a result, it is possible to control the air-fuel ratio in a stable manner while suppressing deterioration of a catalyst.

Abstract: An exhaust emission control device of an internal-combustion engine comprises a three-way catalytic converter provided in an exhaust passage of the internal-combustion engine, and an air-fuel ratio varying element for forcedly varying an air-fuel ratio of exhaust flowing into the three-way catalytic converter, between a rich air-fuel ratio and a lean air-fuel ratio. A variation characteristic altering element for altering a characteristic of the air-fuel ratio variation is provided, and the three-way catalytic converter has a HC selective oxidizing component for selectively oxidizing HC rather than CO, and a CO storage component for storing CO in a reducing atmosphere. The variation characteristic altering element alters a characteristic of the air-fuel variation (such as an A/F variation period) depending on an stored CO quantity correlative value (such as a quantity of flowing-in CO) which correlates with a quantity of CO stored by the CO storage component (S12).

Abstract: An internal combustion engine is comprised of a gas injecting device injecting gas into the combustion chamber of the internal combustion engine, and a gas injection control device controlling the gas injecting device, wherein the gas injection control device provides control such that the gas is injected toward the combustion chamber for a period of time after flame extinguishing timing and before exhaust valve closing timing. Therefore, the internal combustion engine is capable of reliably combusting HC, CO, smoke, and so forth remained in a combustion chamber due to a quenching phenomenon or the like.

Abstract: When exhaust gases flowing into catalysts (e.g., a NOx catalyst and a three-way catalyst) continue to be in the fuel-rich atmosphere for a predetermined period of time or longer, an exhaust emission purifying device for an internal combustion engine leans an air-fuel mixture or supplies the secondary air to the exhaust gases in order to turn the exhaust gases flowing into catalysts into an oxygen-rich atmosphere. This enables the proper regeneration of the degraded catalysts, and thus improves an exhaust emission control performance.

Abstract: An exhaust purifying apparatus includes an exhaust throttle valve provided in an exhaust passage of the internal combustion engine for closing the exhaust passage to increase a pressure therein; a relief passage provided bypassing the exhaust throttle valve; a relief valve provided to be able to close the relief passage and to be open when receiving an increased pressure in the exhaust passage with closure of the exhaust throttle valve; fuel cut determining means for determining whether the engine is during fuel cut-off; and a relief-valve forcibly operating means for closing the exhaust throttle valve when the fuel cut determining means determines that the engine is during fuel cut-off, thereby removing condensed water accumulated in the relief passage to avoid faulty operations of the relief valve, and suppressing deteriorated fuel consumption upon operation of the relief valve.

Abstract: There is provided an exhaust emission control apparatus for an internal combustion engine, which includes a failure diagnostic device that fixes three parameters selected from the group consisting of the engine speed detected by an engine speed detecting device, the fuel quantity controlled by a fuel quantity control device, the ignition timing controlled by an ignition timing control device, and the intake air volume controlled by an intake air control device at respective predetermined values, and finds values of the remaining one parameter, and compares the values of the remaining one parameter with each other to determine whether an exhaust flow control apparatus has failed or not.

Abstract: In an exhaust gas purifying apparatus of an internal combustion engine, the temperature of occlusion-type NOx catalyst is increased to emit SOx when the temperature of occlusion-type NOx catalyst is not less than a set temperature. This prevents the deterioration of fuel consumption and enables the regeneration of a catalyst device by efficiently desorbing a sulfur component from the catalyst device. In this case, the temperature of the occlusion-type NOx catalyst is preferably set according to the frequency of the SOx desorption, and the temperature of the occlusion-type NOx catalyst can be increased by, for example, retarding an ignition timing.

Abstract: Normally, at the time of cold-start of an internal combustion engine or the like, the flow of exhaust in an exhaust passage of the internal combustion engine is suppressed or two-stage combustion is carried out so as to promote exhaust purification in an exhaust system. However, when a correlation value of a braking force required to be generated by a vacuum type brake booster is greater than a correlation value of a braking force that can be aactually generated by the vacuum type brake booster, a restricting device restricts the suppression of the exhaust flow or a two-stage combustion prohibiting device prohibits the two-combustion. Therefore, it is possible to improve an exhaust emission purifying performance while ensuring a braking force by the vacuum type brake booster at the time of braking.

Abstract: An exhaust emission control system for an internal combustion engine includes an exhaust air-fuel ratio changing device switching the exhaust air-fuel ratio of exhaust gas flowing into one of an upstream exhaust passages and the exhaust air-fuel ratio of exhaust gas flowing into the other one of the upstream exhaust passages to a rich air-fuel ratio and to a lean air-fuel ratio alternately on a predetermined cycle longer than each of combustion cycles of the internal combustion engine, to thereby determine whether upstream catalytic converters have deteriorated or not according to a change in the exhaust air-fuel ratio outputted by upstream exhaust sensors provided downstream of the upstream catalytic converters. Therefore, it is possible to surely determining whether catalytic converters have deteriorated even slightly or not while ensuring a high exhaust emission control performance.

Abstract: An exhaust passage (20) of an internal-combustion engine (1) is provided with exhaust emission control means (40) capable of reducing harmful substances in exhaust gas under a given exhaust pressure condition and an exhaust sensor (22) for detecting the concentration of a specific exhaust component (H2, O2) in the exhaust gas, and performance lowering identifying means identifies lowering of the performance of the exhaust emission control means (40) by detecting a failure to fulfill the given exhaust pressure condition in accordance with the output of the exhaust sensor.

Abstract: In an exhaust gas purifying apparatus of an internal combustion engine, the temperature of occlusion-type NOx catalyst is increased to emit SOx when the temperature of occlusion-type NOx catalyst is not less than a set temperature. This prevents the deterioration of fuel consumption and enables the regeneration of a catalyst device by a efficiently desorbing a sulfur component from the catalyst device. In this case, the temperature of the occlusion-type NOx catalyst is preferably set according to the frequency of the SOx desorption, and the temperature of the occlusion-type NOx catalyst can be increased by, for example, retarding an ignition timing.

Abstract: An exhaust emission purifier includes a catalyst unit disposed in an exhaust pipe of an engine. Electrodes (reaction adjustment unit) are provided on a honeycomb carrier of the catalyst unit in a layered form in order to apply an electric field to the vicinity of the catalyst surface to thereby adjust the catalytic reaction. An ECU serves as a status detection unit to detect factors which affect the exhaust gas purifying performance of the catalyst unit (i.e., operating conditions), and serves as a control unit which controls the electric field applied by the electrodes, on the basis of the detected operating conditions.

Abstract: The present plasma type exhaust gas cleaning apparatus comprises a dielectric (5) arranged between a discharge electrode (7) and a ground electrode (8). The dielectric has a plurality of independent cavities (6) formed therein. The exhaust gas from combustion equipment (1) flows through the interiors of the plurality of independent cavities (6). Thus, in the plasma type exhaust gas cleaning apparatus, the discharge electrode (7) and the ground electrode (8) are securely partitioned by the cavities (6). When a voltage from a high voltage generator (9) is applied to between the discharge electrode (7) and the ground electrode (8), plasma resulting from corona discharges occurs in each individual cavity (6) without arising directly across the discharge electrode (7) and the ground electrode (8). The exhaust gas is thereby cleaned up.