Abstract: A method of purifying NOX contained in exhaust gas, the method including a first NOX purification method and a second NOX purification method, wherein the first NOX purification method and the second NOX purification method include injecting hydrocarbons into an exhaust gas passage at predetermined feed intervals, wherein in the first method, the injected hydrocarbons are partially oxidized and an air-fuel ratio flowing into an exhaust purification catalyst is lean, and in the second method, the injection of the hydrocarbons occurs at intervals longer than the predetermined feed intervals in the first method, and an air-fuel ratio is switched from lean to rich.

Abstract: In an internal combustion engine, an exhaust purification catalyst: (13), particulate filter (14), and hydrocarbon feed valve (15) are arranged in an engine exhaust passage. A low pressure exhaust gas recirculation system (LPL) is provided for making the exhaust gas downstream of the particulate filter (14) recirculate. If hydrocarbons are injected from the hydrocarbon feed valve (15), the carbon dioxide which is produced in the exhaust purification catalyst (13) is recirculated and the air-fuel ratio of the exhaust gas which flows into the exhaust purification catalyst (13) temporarily drops. At the time of regeneration of the particulate filter (14), hydrocarbons are injected from, the hydrocarbon feed valve (15) so as not to overlap with this temporary drop of the air-fuel ratio.

Abstract: A method for purifying exhaust gas of an internal combustion engine including flowing an exhaust gas containing NOx and a concentration of hydrocarbons in an exhaust gas passage that contains an exhaust purification catalyst, wherein the concentration of hydrocarbons is vibrated within a predetermined range of amplitude and period, and a least a portion of the hydrocarbons are reformed by the exhaust purification catalyst; reacting the NOx contained in the exhaust gas and the reformed hydrocarbons to produce a reducing intermediate; and chemically reducing, wherein at the time of engine operation, a demanded produced amount of the reducing intermediate required for chemically reducing the NOx is calculated, and the amplitude and vibration period of the concentration of hydrocarbons flowing into the exhaust purification catalyst are controlled so that an amount of the reducing intermediate produced becomes the demanded produced amount.

Abstract: An exhaust purification system of an internal combustion engine is provided with an exhaust purification catalyst where NOX which is contained in exhaust gas and modified hydrocarbons react. The exhaust purification catalyst carries precious metal catalysts and is formed with a basic exhaust gas flow surface part. The exhaust purification catalyst has the property of reducing NOX if making the concentration of hydrocarbons which flow into the exhaust purification catalyst vibrate by within a predetermined range of amplitude and within a predetermined range of period. The system estimates the holding ability by which the NOX in the exhaust gas is held on the basic exhaust gas flow surface part of the exhaust purification catalyst and, when the holding ability becomes less than a predetermined judgment value of the holding ability, makes the concentration of hydrocarbons which flow into the exhaust purification catalyst rise.

Abstract: In an internal combustion engine of the present invention, an exhaust purification catalyst (13) and a hydrocarbon supply valve (15) are disposed in an engine exhaust path, and NOx contained in exhaust gas is purified by injecting hydrocarbon from the hydrocarbon supply valve (15) at a predetermined cycle. With respect to the injection amount per unit time of the hydrocarbon from the hydrocarbon supply valve (15), there is a difference provided between the first half and the second half of one injection time period, and in the first-half injection time period (Y), the injection amount per unit time of hydrocarbon is made to be less as compared to the second-half injection time period (X).

Abstract: An exhaust purification system of an internal combustion engine provided with an exhaust purification catalyst which reacts NOX and hydrocarbons. The exhaust purification catalyst includes an upstream side catalyst and a downstream side catalyst. The upstream side catalyst has an oxidation ability, while the downstream side catalyst carries precious metal catalyst particles on the exhaust flow surface and is formed with basic exhaust flow surface parts. The exhaust purification catalyst can make the concentration of hydrocarbons vibrate by within a predetermined range of amplitude and by within a predetermined range of period so as to partially oxidize the hydrocarbons or produce reducing intermediates at the upstream side catalyst. When the temperature of the upstream side catalyst is less than a first judgment temperature and the temperature of the downstream side catalyst is higher than a second judgment temperature, the temperature of the upstream side catalyst is made to rise.

Abstract: An exhaust gas purification apparatus for an internal combustion engine comprises a NOx selective reduction catalyst provided in an exhaust passage of an internal combustion engine; an upstream side oxidation catalyst which is a catalyst having an oxidizing ability provided in the exhaust passage upstream from the NOx selective reduction catalyst and which includes a carrier for carrying a noble metal for oxidation, the carrier being formed of a basic carrier; and a reducing agent supply until which supplies a reducing agent to an exhaust gas allowed to flow into the NOx selective reduction catalyst. Accordingly, even when the oxidation catalyst causes the SOx poisoning in the exhaust gas purification apparatus for the internal combustion engine having the oxidation catalyst and the NOx selective reduction catalyst provided in the exhaust passage, the reduction efficiency of NOx reduced by the aid of the NOx selective reduction catalyst is favorably maintained.

Abstract: In an internal combustion engine, inside of an engine exhaust passage, a hydrocarbon feed valve (15) and an exhaust purification catalyst (13) are arranged. The concentration of hydrocarbons which flows into the exhaust purification catalyst (13) is made to vibrate by within a predetermined range of amplitude of a 200 ppm or more and within a predetermined range of period of 5 second or less, whereby the NOx which is contained in exhaust gas is reduced at the exhaust purification catalyst (13). At this time, the nitrogen-containing intermediate which is produced in the NOx reduction process is exhausted from the exhaust purification catalyst (13). An intermediate purification catalyst (14) for removal of the exhausted nitrogen-containing intermediate is arranged downstream of the exhaust purification catalyst (13).

Abstract: A three-way catalyst (20) having an oxygen storage function and an exhaust purification catalyst (22) are arranged in the exhaust passage of an internal combustion engine. During medium-load operation of the engine the degree of lean of the air-fuel ratio in the combustion chamber (5) is increased so as to increase the oxygen storage amount of the three-way catalyst (20) to the maximum oxygen storage amount, and the air-fuel ratio in the combustion chamber (5) even after the oxygen storage amount of the three-way catalyst (20) has reached the maximum oxygen, storage amount is maintained at lean, after which the air-fuel ratio is returned to rich, and at this time, as the amount of poisoning of a noble metal catalyst when the air-fuel ratio in the combustion chamber (5) is rich increases, the amount of time for which the air-fuel ratio in the combustion chamber (5) is maintained at lean is increased.

Abstract: In an internal combustion engine, an exhaust purification catalyst: (13), particulate filter (14), and hydrocarbon feed valve (15) are arranged in an engine exhaust passage. A low pressure exhaust gas recirculation system (LPL) is provided for making the exhaust gas downstream of the particulate filter (14) recirculate. If hydrocarbons are injected from the hydrocarbon feed valve (15), the carbon dioxide which is produced in the exhaust purification catalyst (13) is recirculated and the air-fuel ratio of the exhaust gas which flows into the exhaust purification catalyst (13) temporarily drops. At the time of regeneration of the particulate filter (14), hydrocarbons are injected from, the hydrocarbon feed valve (15) so as not to overlap with this temporary drop of the air-fuel ratio.

Abstract: In an internal combustion engine, inside of an engine exhaust passage, a hydrocarbon feed valve (15) and an exhaust purification catalyst (13) are arranged. At the time of engine operation, the amplitude of change of the concentration of hydrocarbons which flow into the exhaust purification catalyst (13) is made to become within a predetermined range of amplitude by control of at least one of the injection time and injection pressure of hydrocarbons from the hydrocarbon feed valve (15). In this case, when only the injection time of hydrocarbons is controlled, the injection time of hydrocarbons under the same engine operating state is made longer the higher the temperature of the exhaust purification catalyst (13).

Abstract: An internal combustion engine wherein an exhaust purification catalyst and hydrocarbon feed valve are arranged in an engine exhaust passage and wherein the NOX which is contained in the exhaust gas is removed by injection of hydrocarbons from the hydrocarbon feed valve by a predetermined period. Hydrocarbons are injected from the hydrocarbon feed valve toward the upstream side of the engine exhaust passage. When hydrocarbons are injected from the hydrocarbon feed valve by a predetermined period, the injection pressure of the hydrocarbons is made to gradually fall from injection start to injection end in the injection time period of each injection.

Abstract: An exhaust purification system of an internal combustion engine is provided with a hydrocarbon feed valve arranged in an engine exhaust passage and an exhaust purification catalyst for causing NOX contained in exhaust gas and reformed hydrocarbons to react. The exhaust purification catalyst reduces NOX if a concentration of inflowing hydrocarbons vibrates within a predetermined range of amplitude and within a predetermined range of period and increases the amount of storage of NOX if the vibration period of the concentration of hydrocarbons longer is than a predetermined range. When hydrocarbons are being fed from the hydrocarbon feed valve within the predetermined range of amplitude and the predetermined range of period, if the amount of adsorption of hydrocarbons in the exhaust purification catalyst exceeds a predetermined judgment value of the adsorption amount, at least one of reducing amount of feed of hydrocarbons and lengthening feed interval of hydrocarbons is performed.

Abstract: An exhaust purification system of an internal combustion engine is provided with an exhaust purification catalyst which includes an upstream side catalyst and a downstream side catalyst and removes NOX. The upstream side catalyst has an oxidation ability, while the downstream side catalyst has catalyst particles of precious metals and basic exhaust flow surface parts. The system makes the concentration of hydrocarbons which flow into the exhaust purification catalyst vibrate by within a predetermined range of amplitude and by within a predetermined range of period and reduces the NOX. The upstream side catalyst includes an upstream side substrate and an upstream side container, while the downstream side catalyst includes a downstream side substrate, a downstream side container, and a channel of exhaust between the downstream side substrate and the downstream side container.

Abstract: In an internal combustion engine, inside of an engine exhaust passage, a hydrocarbon feed valve (16), an exhaust purification catalyst (13), an aqueous urea solution feed valve (17), and an NOx selective reduction catalyst (15) are arranged in that order. A first NOx purification method which makes the concentration of hydrocarbons flowing into the exhaust purification catalyst (13) vibrate by within predetermined ranges of amplitude and period to reduce the NOx contained in exhaust gas in the exhaust purification catalyst (13) is normally used. A second NOx purification method which uses the fed aqueous urea solution to reduce the NOx in the NOx selective reduction catalyst (15) is used when the fed hydrocarbons exceed the allowable value.

Abstract: In an engine, an exhaust purification catalyst (13) and a hydrocarbon feed valve (15) are arranged in an engine exhaust passage, and, a low pressure exhaust gas recirculation system (LPL) which makes exhaust gas downstream of the exhaust purification catalyst (13) recirculate is provided. If hydrocarbons are injected from the hydrocarbon feed valve (15), a carbon dioxide which is generated at the exhaust purification catalyst (13) is recirculated, and the air-fuel ratio of the exhaust gas which flows into the exhaust purification catalyst (13) temporarily drops. Hydrocarbons are injected from the hydrocarbon feed valve (15) in synchronization with this temporary drop in the air-fuel ratio.

Abstract: An internal combustion engine wherein a hydrocarbon feed valve (15) and an exhaust purification catalyst (13) are arranged inside of an engine exhaust passage. At the time of engine operation, the amount of injection of hydrocarbons from the hydrocarbon feed valve (15) is controlled so that an amplitude of change of concentration of hydrocarbons which flow into the exhaust purification catalyst (13) becomes within a predetermined range of amplitude, and the injection period of hydrocarbons from the hydrocarbon feed valve (15) is controlled so that a concentration of hydrocarbons which flow into the exhaust purification catalyst (13) vibrates within a predetermined range of period. The exhaust purification catalyst (13) is formed so that a deposition ability of hydrocarbons to a downstream side part of the exhaust purification catalyst (13) becomes higher than a deposition ability of hydrocarbons to an upstream side part of the exhaust purification catalyst (13).

Abstract: In an internal combustion engine, inside of an engine exhaust passage, a hydrocarbon feed valve and an exhaust purification catalyst are arranged. On the exhaust purification catalyst, platinum Pt is carried and a basic layer is formed. The concentration of hydrocarbons which flows into the exhaust purification catalyst is made to vibrate by within a predetermined range of amplitude and a predetermined range of period due to which the NOx which is contained in exhaust gas is reduced at the exhaust purification catalyst. At this time, the greater the oxidizing strength of the exhaust purification catalyst, the greater the injection pressure of hydrocarbons from the hydrocarbon feed valve.

Abstract: An exhaust purification system of an internal combustion engine is provided with an exhaust purification catalyst which includes an upstream side catalyst and a downstream side catalyst and which makes NOX and hydrocarbons react. The upstream side catalyst has an oxidation ability, while the downstream side catalyst carries precious metal catalyst particles on an exhaust flow surface and is formed with basic exhaust flow surface parts. The exhaust purification catalyst makes the concentration of hydrocarbons vibrate by within a predetermined range of amplitude and by within a predetermined range of period so as to remove the NOX. The upstream side catalyst has a high efficiency temperature at which hydrocarbons can be partially oxidized by a predetermined efficiency.

Abstract: In an internal combustion engine, inside of an engine exhaust passage, a hydrocarbon feed valve (15) and an exhaust purification catalyst (13) are arranged. The exhaust purification catalyst (13) is comprised of an upstream-side catalyst (14a) and a downstream-side catalyst (14b) arranged in series at an interval from each other. The upstream-side catalyst (14b) has a smaller cross-sectional area than the downstream-side catalyst (14b). The concentration of hydrocarbons which flow into the upstream-side catalyst (14a) is made to vibrate by within a predetermined range of amplitude of a 200 ppm or more and within a predetermined range of period of 5 seconds or less, whereby the NOx which is contained in exhaust gas is reduced at the exhaust purification catalyst (13).