Abstract: An internal combustion engine in which an SOx trapping catalyst (12) and particulate filter (13) are arranged in a engine exhaust passage and in which a recirculation exhaust gas takeout port (17) is formed in the engine exhaust passage downstream of the particulate filter (13). Inside the engine exhaust passage downstream of the recirculation exhaust gas takeout port (17), an NOx storing catalyst (15) and a reducing agent feed valve (21) are arranged. When NOx should be released from the NOx storing catalyst (15), reducing agent is fed into the exhaust passage from the reducing agent feed valve (21).

Abstract: In an internal combustion engine, the engine is formed so that an output of an electric motor can be superposed on an output of the engine. In the engine exhaust passage upstream of the NOX storage catalyst, an SOX trap catalyst able to trap the SOX contained in the exhaust gas is arranged. When regenerating the SOX trap catalyst, the vehicle drive power from the engine and the vehicle drive power from the electric motor are adjusted so that the SOX concentration in the exhaust gas flowing out from the SOX trap catalyst becomes less than a predetermined SOX concentration during the regeneration period.

Abstract: A fuel addition valve that adds fuel into the exhaust gas passage of the engine in the form of fine fuel droplets, an upstream NOx adsorption-reduction catalyst, and a downstream NOx adsorption-reduction catalyst are arranged in this order. Platinum Pt and palladium Pd, as noble metal, are supported on the downstream NOx adsorption-reduction NOx catalyst such that the ratio of the mole number of the platinum Pt to the sum of the mole numbers of the platinum Pt and the palladium Pd is approx. 50% to approx. 80%. Only platinum Pt is supported on the upstream NOx adsorption-reduction catalyst. According to this structure, even when liquid fuel is supplied into exhaust gas, NOx can be effectively released from the NOx adsorption-reduction catalyst, and further the amount of NOx that the NOx adsorption-reduction catalyst can adsorb at a low temperature increases.

Abstract: A device for purifying exhaust gas of an internal combustion engine comprising a NOx catalyst device, fuel feeding means for feeding additional fuel into combusted gas flowing into the NOx catalyst device during the regeneration treatment, and a NOx concentration sensor arranged on the exhaust downstream of the NOx catalyst device, wherein when the NOx concentration detected by the NOx concentration sensor is lower than a preset concentration during the regeneration treatment of this time, the amount of NOx absorbed by the NOx catalyst device during a preset period until the regeneration treatment of the next time is estimated by utilizing the NOx concentration sensor, and when the absorbed amount of NOx is smaller than a preset amount, it is decided that the amount of additional fuel fed during the regeneration processing of this time had been abnormally decreased.

Abstract: An SOX trap catalyst 12 and NOX purification catalyst 13 are arranged in an engine exhaust passage. A substrate 50 of the NOX purification catalyst 13 is formed with a coat layer comprised of at least the two layers of an upper coat layer 51 and a lower coat layer 52. The lower coat layer 52 is formed from an NOX storage catalyst storing the NOX contained in the exhaust gas when the air-fuel ratio of the exhaust gas is lean and releasing the stored NOX when the air-fuel ratio of the exhaust gas is a stoichiometric air-fuel ratio or rich. The upper coat layer 51 is formed from a material of a weaker basicity than this NOX storage catalyst.

Abstract: An engine exhaust passage has an SOx trapping catalyst (11), a particulate filter (13) holding an NOx storing/reducing catalyst, and an NOx storing/reducing catalyst (15) forming a post-treatment system and a fuel feed valve (17) for feeding fuel for post processing in the post-treatment system arranged inside it. When any catalyst has a degree of degradation exceeding a predetermined degree of degradation, the method of feeding the post-treatment fuel is reset so that the post-treatment fuel required for purification of the exhaust gas can be fed into the catalyst with the lowest degree of degradation to make the catalyst with the lowest degree of degradation handle the purification action of the exhaust gas.

Abstract: An exhaust gas control apparatus for an internal combustion engine is provided with an exhaust catalyst disposed in an exhaust passage (4) of the internal combustion engine, a concentration detection unit (10) that is capable of detecting a total concentration of a sulfur oxide and a hydrogen sulfide contained in an exhaust gas that passes through the exhaust catalyst, and detecting a concentration of the sulfur oxide, and a sulfur concentration estimation unit (15) that estimates a concentration of sulfur contained in a fuel based on a detection value of the concentration detection unit (10) when it is determined that the exhaust gas is at one of a stoichiometric and rich air/fuel ratio.

Abstract: A device for purifying exhaust gas of an internal combustion engine is provided, equipped with an HC catalyst having the ability to oxidize HC, as well as adsorb HC, and release HC which it has adsorbed, and there exists a specific condition where the amount to release HC becomes greater than the amount to oxidize HC, wherein the device for purifying exhaust gas of an internal combustion engine executes an HC feed control for feeding HC to the HC catalyst. The amount of HC fed to the HC catalyst is decreased by the HC feed control or the HC feed control is discontinued when the specific condition is established during execution of the HC feed control.

Abstract: An engine exhaust passage is provided with a fuel addition valve (14) for adding fuel in the form of atomized drops, an oxidation catalyst (11), and an NOx storage and reduction catalyst (12) in that order. The oxidation catalyst (11) carries as a precious metal not only platinum Pt, but also palladium Pd. A molar ratio of the platinum Pt with respect to the sum of the platinum Pt and palladium Pd carried on the oxidation catalyst (11) is set to between about 50 percent to about 80 percent.

Abstract: A device for purifying the exhaust gas of an internal combustion engine is disclosed. The device includes a particulate filter arranged in the exhaust system, which carries a catalyst for absorbing and reducing NOx. The catalyst absorbs NOx when the air-fuel ratio in the surrounding atmosphere thereof is lean and releases the absorbed NOx to purify NOx by reduction when the air-fuel ratio is stoichiometric or rich. The device further includes a catalytic apparatus for purifying NOx arranged in the exhaust system upstream of the particulate filter, which has an oxidation function.

Abstract: There are provided a NOx storage reduction catalyst which is provided in an exhaust passage for an engine, and a sulfur concentration sensor which can detect a total concentration of SOx and H2S in exhaust gas that has passed through the NOx catalyst, and a concentration of SOx in the exhaust gas. An operating state of the engine is controlled such that SOx is released from the NOx catalyst (sulfur poisoning recovery process). When a concentration of the hydrogen sulfide obtained based on the total concentration and the concentration of SOx that are detected by the sulfur concentration sensor during the sulfur poisoning recovery process exceeds a permissible limit, an operating state of the engine is controlled such that the sulfur oxide is released from the NOx catalyst, an amount of the released sulfur oxide is in a predetermined range, and the concentration of the hydrogen sulfide is reduced.

Abstract: An exhaust gas control apparatus for an internal combustion engine is provided with an exhaust catalyst disposed in an exhaust passage (4) of the internal combustion engine, a concentration detection unit (10) that is capable of detecting a total concentration of a sulfur oxide and a hydrogen sulfide contained in an exhaust gas that passes through the exhaust catalyst, and detecting a concentration of the sulfur oxide, and a sulfur concentration estimation unit (15) that estimates a concentration of sulfur contained in a fuel based on a detection value of the concentration detection unit (10) when it is determined that the exhaust gas is at one of a stoichiometric and rich air/fuel ratio.

Abstract: An exhaust purification device, including a NOx storing catalyst comprised of a precious metal catalyst and NOx absorbent, arranged in an engine exhaust passage, which increases the ratio of the nitrogen dioxide to the nitrogen monoxide produced when burning fuel under a lean air-fuel ratio when the NOx storing catalyst is not active compared with the time when the NOx storing catalyst is active under the same engine operating conditions and stores the nitrogen dioxide contained in the exhaust gas in the NOx absorbent at that time.

Abstract: There are provided a NOx storage reduction catalyst which is provided in an exhaust passage for an internal combustion engine, and concentration detection means whose detection state can be changed between a first detection state in which a total concentration of sulfur oxide and hydrogen sulfide in exhaust gas that has passed through the NOx catalyst is detected, and a second detection state in which a concentration of the sulfur oxide in the exhaust gas is detected. An operating state of the internal combustion engine is controlled such that the sulfur oxide is released from the NOx catalyst (sulfur poisoning recovery process).

Abstract: There are provided a NOx storage reduction catalyst which is provided in an exhaust passage for an internal combustion engine, and concentration detection means whose detection state can be changed between a first detection state in which a total concentration of sulfur oxide and hydrogen sulfide in exhaust gas that has passed through the NOx catalyst is detected, and a second detection state in which a concentration of the sulfur oxide in the exhaust gas is detected. An operating state of the internal combustion engine is controlled such that the sulfur oxide is released from the NOx catalyst (sulfur poisoning recovery process).

Abstract: An exhaust gas purification apparatus for an engine having a combustion chamber includes a device that prevents overheating of a particulate filter. The apparatus includes an exhaust passage, a particulate filter arranged in the exhaust passage for removing particulate in exhaust gas exhausted from the combustion chamber by oxidation, and a device for controlling the characteristics of the exhaust gas flowing into the particulate filter. A judgment is made whether the particulate filter will be deteriorated by heat. If yes, the controlling device changes the characteristics of the exhaust gas flowing into the particulate filter to prevent the particulate filter from being deteriorated by heat.

Abstract: A fuel adding valve (14), an HC adsorbing and oxidation catalyst (11), and a NOx storing catalyst (12) are successively arranged in an exhaust passage of an internal combustion engine toward the downstream side. When the NOx storing catalyst (12) should release NOx, particulate fuel is added from the fuel adding valve (14). This fuel is adsorbed once at the HC adsorbing and oxidation catalyst (11), then gradually evaporates to make the air-fuel ratio of the exhaust gas flowing into the NOx storing catalyst (12) rich. Due to this, NOx is released from the NOx storing catalyst (12).

Abstract: A NOx storing catalyst (11) comprising a precious metal catalyst (46) and NOx absorbent (47) is arranged in an exhaust passage. When the air-fuel ratio of the exhaust gas is lean, the storing catalyst cold stores the NO2 contained in the exhaust in the absorbent when the catalyst is inactive and hot stores the cold stored NO2 in the absorbent when the catalyst is made active. The NO2 contained in the exhaust is cold stored in the absorbent when the catalyst is not activated, and when a predetermined NOx storing catalyst restoring condition (107) is met, a NOx storing catalyst restoring control (109, 115) including raising the NOx storing catalyst temperature to a predetermined temperature to active it (109) is executed so as to restore the cold storing capability of the NOx absorbent.

Abstract: An exhaust emission purification device comprises a sulfur component holding agent arranged on the exhaust path of an internal combustion engine for holding a sulfur component, a NOx holding agent arranged downstream of the sulfur component holding agent in the exhaust gas for holding NOx and the sulfur components when the air-fuel ratio of the exhaust gas flowing thereinto is lean, and a reducing agent adding unit for adding a reducing agent to the exhaust gas flowing into the NOx holding agent. The concentration of the sulfur component contained in the reducing agent added by the reducing agent adding unit is lower than the concentration of at least the sulfur component contained in the fuel supplied to the combustion chamber of the internal combustion engine. Thus, the sulfur poisoning of the exhaust emission purifier can be avoided while at the same time reducing the fuel consumption rate.

Abstract: In an exhaust gas control device-equipped internal combustion engine, particulate matter produced in conjunction with combustion of gasoline in a combustion chamber is oxidized by an exhaust gas control device provided in an exhaust passage. The engine includes air-fuel ratio control changer that changes between a feedback control toward a stoichiometric air-fuel ratio whereby an amount of oxygen in exhaust gas is reduced and a feedback control toward a lean-burn combustion side whereby the amount of oxygen in exhaust gas is increased, if the oxidation speed of particulate matter in the exhaust gas control device provided in the exhaust passage is slow, or if the amount of deposit of particulate matter is great.