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AssigneeToyota Jidosha Kabushiki Kaisha
InventorsShinichi Takeshima, Toshiaki Tanaka, Satoshi Iguchi, Yasushi Araki, Shinya Hirota, Tomohiro Oda, Fumitada Murakami
Estimating the term…
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.
An exhaust purification device of an internal combustion engine which has in an engine exhaust passage a NO.sub.x absorbent which absorbs NO.sub.x when the air-fuel ratio of the inflowing exhaust gas is lean and which releases the absorbed NO.sub.x when the oxygen concentration in the inflowing exhaust gas is reduced and which is provided with a NO.sub.x estimating means for estimating the amount of the NO.sub.x absorbed by the NO.sub.x absorbent and a NO.sub.x releasing means for reducing the oxygen concentration in the exhaust gas flowing into the NO.sub.x absorbent and releasing NO.sub.x from the NO.sub.x absorbent when the amount of the NO.sub.x estimated to be absorbed in the NO.sub.x absorbent by the NO.sub.x estimating means exceeds a predetermined allowable value.
Dependencies are inferred from the claim text.