US 5,473,890 AGranted

Exhaust purification device of internal combustion engine

AssigneeToyota Jidosha Kabushiki Kaisha

InventorsShinichi Takeshima, Satomi Seto, Toshiaki Tanaka, Satoshi Iguchi, Kiyoshi Nakanishi, Kenji Katoh

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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 ).

Claims37

Dependent claims

An exhaust purification device of an internal combustion engine provided with:

an exhaust passage;
an NO.sub.x absorbent which is arranged in said exhaust passage, absorbs the NO.sub.x when the air-fuel ratio of an inflowing exhaust gas is lean and, at the same time, releases the absorbed NO.sub.x when an oxygen concentration in the inflowing exhaust gas is lowered;
an SO.sub.x absorbent which is arranged in said exhaust passage on the upstream side of said NO.sub.x absorbent, absorbs the SO.sub.x when the air-fuel ratio of the inflowing exhaust gas is lean and, at the same time, releases the absorbed SO.sub.x when the air-fuel ratio of the inflowing exhaust gas is made rich;
and
an air-fuel ratio control means which controls the air-fuel ratio of the exhaust gas flowing into said SO.sub.x absorbent, usually maintains the air-fuel ratio of the exhaust gas flowing into said SO.sub.x absorbent lean, and makes the air-fuel ratio of the exhaust gas flowing into said SO.sub.x absorbent rich when the SO.sub.x should be released from said SO.sub.x absorbent.

2 more elements

Dependencies are inferred from the claim text.