Abstract: An exhaust purification device which is capable of detecting the degree of deterioration of the NOx absorbent or the three-way catalyst arranged in the exhaust passage of an engine. An O.sub.2 sensor whose output current or output voltage is proportional to the air-fuel ratio is arranged inside the exhaust passage downstream of the NOx absorbent or three-way catalyst. The air-fuel ratio of the air-fuel mixture is temporarily changed from lean to rich or from rich to lean to enable the degree of deterioration of the NOx absorbent or three-way catalyst to be detected from the peak value of the output current or voltage of the O.sub.2 sensor during the time when the air-fuel ratio is changed.

Abstract: An NO.sub.x absorber (18) is arranged in an exhaust passage of an internal combustion engine. The NO.sub.x absorber (18) absorbs the NO.sub.x when the air-fuel ratio of the exhaust gas flowing into the NO.sub.x absorber (18) is lean while releases the absorbed NO.sub.x when the air-fuel ratio of the exhaust gas flowing into the NO.sub.x absorber (18) becomes the stoichiometric air-fuel ratio or rich. An air-fuel ratio sensor (22) is arranged in the exhaust passage downstream of the NO.sub.x absorber (18). When the air-fuel ratio detected by the air-fuel ratio sensor (22) is switched from lean to rich after the air-fuel ratio of the exhaust gas flowing into NO.sub.x absorber (18) is switched from lean to rich, it is decided that the releasing action of NO.sub.x from the NO.sub.x absorber (18) is completed.

Abstract: An NO.sub.x absorbent (19) which absorbs NO.sub.x when an air-fuel ratio of an inflowing exhaust gas is lean, while releases the absorbed NO.sub.x when lowering an oxygen concentration in the inflowing exhaust gas, is arranged in an exhaust passage of an internal combustion engine. An SO.sub.x absorbent (18) which absorbs SO.sub.x when the air-fuel ratio of the inflowing exhaust gas is lean, while releases the absorbed SO.sub.x when the air-fuel ratio of the inflowing exhaust gas is made rich is arranged in the exhaust passage on the upstream side of the NO.sub.x absorbent (19). When the lean air-fuel mixture is burned, the SO.sub.x is absorbed into the SO.sub.x absorbent (18) and, at the same time, the NO.sub.x is absorbed into the NO.sub.x absorbent (19), and when the air-fuel ratio of the air-fuel mixture is switched from lean to rich, SO.sub.x is released from the SO.sub.x absorbent (18), and NO.sub.x is released from the SO.sub.x absorbent (19 ).

Abstract: An NO.sub.x absorbent (18) is disposed in an exhaust passage of an internal combustion engine and the exhaust gas is constantly made to circulate through the NO.sub.x absorbent (18) during the operation of the engine. The NO.sub.x absorbent (18) absorbs the NO.sub.x when the air-fuel ratio of the exhaust gas flowing into the NO.sub.x absorbent (18) is lean and releases the absorbed NO.sub.x when the air-fuel ratio of the exhaust gas flowing into the NO.sub.x absorbent (18) becomes the stoichiometric air-fuel ratio or rich. In the majority of the engine operation region, the lean air-fuel mixture is burned in the combustion chamber (3), and the NO.sub.x generated at this time is absorbed into the NO.sub.x absorbent (18). The air-fuel ratio of the exhaust gas flowing into the NO.sub.x absorbent (18) is periodically made the stoichiometric air-fuel ratio or rich, and the NO.sub.x absorbed in the NO.sub.x absorbent (18) is released, and simultaneously reduced.

Abstract: An engine comprising an exhaust passage having therein a NO.sub.x absorbent which absorbs the NO.sub.x when the air-fuel ratio of the exhaust gas flowing into the NO.sub.x absorbent is lean and releases the absorbed NO.sub.x when the air-fuel ratio of the exhaust gas flowing into the NO.sub.x absorbent becomes the stoichiometric air-fuel ratio or rich. A sulphur trapping device for trapping SO.sub.x contained in the exhaust gas is arranged in the exhaust passage upstream of the NO.sub.x absorbent.

Abstract: A NO.sub.x absorbent (17) is disposed in an exhaust passage of an internal combustion engine. This NO.sub.x absorbent (17) absorbs the NO.sub.x when the air-fuel ratio of the exhaust gas flowing into the NO.sub.x absorbent (17) is lean and releases the absorbed NO.sub.x when the air-fuel ratio of the exhaust gas flowing into the NO.sub.x absorbent (17) becomes rich. When making the air-fuel ratio of the exhaust gas flowing into the NO.sub.x absorbent (17) rich to release the NO.sub.x from the NO.sub.x absorbent (17), the degree of richness is made larger and the time the ratio is made rich is made shorter the higher the temperature of the NO.sub.x absorbent (17).

Abstract: A NO.sub.x absorbent (17) is disposed in an exhaust passage of an internal combustion engine. This NO.sub.x absorbent (17) absorbs the NO.sub.x when the air-fuel ratio of the exhaust gas flowing into the NO.sub.x absorbent (17) is lean and releases the absorbed NO.sub.x when the air-fuel ratio of the exhaust gas flowing into the NO.sub.x absorbent (17) becomes rich. It estimates the amount of NO.sub.x absorbed in the NO.sub.x absorbent (17) from the engine load and the engine rotational speed and when the amount of the estimated NO.sub.x becomes the maximum NO.sub.x absorption capacity of the NO.sub.x absorbent (17), makes the air-fuel ratio of the exhaust gas flowing into the NO.sub.x absorbent (17) rich.

Abstract: An engine comprising an exhaust passage having therein a NO.sub.x absorbent which absorbs the NO.sub.x when the air-fuel ratio of the exhaust gas flowing into the NO.sub.x absorbent is lean and releases the absorbed NO.sub.x when the air-fuel ratio of the exhaust gas flowing into the NO.sub.x absorbent becomes the stoichiometric air-fuel ratio or rich. A catalyst having an O.sub.2 storage function is arranged in the exhaust passage downstream of the NO.sub.x absorbent. When NO.sub.x is to be released from the NO.sub.x absorbent, the air-fuel ratio of the exhaust gas is made rich to an extent such that the amount of unburned HC and CO is excessive beyond an amount necessary to reduce the whole NO.sub.x.

Abstract: An engine comprising an exhaust passage having therein a NO.sub.x absorbent which absorbs the NO.sub.x when the air-fuel ratio of the exhaust gas flowing into the NO.sub.x absorbent is lean and releases the absorbed NO.sub.x when the air-fuel ratio of the exhaust gas flowing into the NO.sub.x absorbent becomes the stoichiometric air-fuel ratio or rich. When the air-fuel ratio of the air-fuel mixture should be changed over from lean to the stoichiometric air-fuel ratio, the air-fuel ratio of the air-fuel mixture is temporarily made rich and is then made the stoichiometric air-fuel ratio.

Abstract: A NO.sub.x absorbent (18) which absorbs the NO.sub.x when the air-fuel ratio of the exhaust gas flowing into the NO.sub.x absorbent (18) is lean and releases the absorbed NO.sub.x when the oxygen concentration of the exhaust gas flowing into the NO.sub.x absorbent (18) is lowered, is arranged in the exhaust passage of the engine. The amount of alkali metals, alkali-earth metals or rare-earth metals contained in the NO.sub.x absorbent (18) positioned on the downstream side, is made lower than the amount of alkali metals, alkali-earth metals or rare-earth metals contained in the NO.sub.x absorbent (18) positioned on the upstream side, to increase a reducing ability of the NO.sub.x absorbent (18) positioned on the downstream side as compared to the reducing ability of the NO.sub.x absorbent (18) positioned on the upstream side.

Abstract: An NOx absorbent is installed in an exhaust conduit of an internal combustion engine capable of fuel combustion at lean air-fuel ratios. An oxygen concentration is repeatedly or continuously decreased by, for example, switching the air-fuel from the lean air-fuel ratio to a stoichiometric or rich air fuel ratio when the exhaust gas temperature is higher than 550.degree. C. or when NOx absorbent temperature is higher than 500.degree. C. As a result, the SOx absorbed in the NOx absorbent during lean air-fuel ratio, low temperature operation is released from the NOx absorbent, and the SOx-poisoned NOx absorbent is recovered.

Abstract: An exhaust gas purification system includes a transition metal/zeolite first catalyst, a three-way second catalyst, and a noble metal-type third catalyst arranged in that order in the direction of exhaust gas flow in an exhaust conduit of an internal combustion engine capable of fuel combustion at lean air-fuel ratios. NOx which has not been purified by the transition metal/zeolite first catalyst is oxidized by the three-way second catalyst into NO.sub.2, which the noble metal-type third catalyst can easily decompose into N.sub.2 and O.sub.2.

Abstract: A fuel injector comprising a pair of air passages which are joined at the nozzle opening, whereby fuel injected from the fuel supply bore is joined with the airstreams flowing in the air passages. At this time, the fuel is carried by the airstreams and thus flows through the air passages at a high speed, and accordingly, the fuel is caused to impinge against the inner wall of the nozzle opening at a high speed.