Engine exhaust gas purification device
First Claim
1. An exhaust gas purification device of an engine, comprising:
- air-fuel mixture control means for making an air-fuel mixture burned in a combustion chamber of the engine a rich air-fuel mixture;
a three way catalyst arranged in an exhaust passage of the engine;
a NOx absorbent arranged in said exhaust passage downstream of said three way catalyst, said NOx absorbent absorbing NOx therein when an air-fuel ratio of exhaust gas flowing into said NOx absorbent is lean;
first secondary air supply means for feeding secondary air into said exhaust passage upstream of said three way catalyst;
second secondary air supply means for feeding secondary air into said exhaust passage between said three way catalyst and said NOx absorbent; and
secondary air control means for controlling amounts of secondary air fed from said first secondary air supply means and said second secondary air supply means to maintain the air-fuel ratio of the exhaust gas flowing into said three way catalyst at a rich air-fuel ratio which is larger than an air-fuel ratio of said first mentioned rich air-fuel mixture and to maintain the air-fuel ratio of the exhaust gas flowing into said NOx absorbent at a lean air-fuel ratio.
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Accused Products
Abstract
An exhaust gas purification device comprising a three way catalyst, an oxidizing catalyst and a NOx absorbent which are arranged in this order in the exhaust passage. A rich air-fuel mixture is burned in the combustion chamber, and secondary air is supplied upstream of the three way catalyst so as to make the air-fuel ratio of the exhaust gas flowing into the three way catalyst a rich air-fuel ratio greater than the air-fuel ratio of the air-fuel mixture burned in the combustion chamber. Further, secondary air is supplied upstream of the oxidizing catalyst to make the air-fuel ratio of the exhaust gas flowing into the oxidizing catalyst and the NOx absorbent slightly leaner than the stoichiometric air-fuel ratio.
131 Citations
25 Claims
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1. An exhaust gas purification device of an engine, comprising:
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air-fuel mixture control means for making an air-fuel mixture burned in a combustion chamber of the engine a rich air-fuel mixture; a three way catalyst arranged in an exhaust passage of the engine; a NOx absorbent arranged in said exhaust passage downstream of said three way catalyst, said NOx absorbent absorbing NOx therein when an air-fuel ratio of exhaust gas flowing into said NOx absorbent is lean; first secondary air supply means for feeding secondary air into said exhaust passage upstream of said three way catalyst; second secondary air supply means for feeding secondary air into said exhaust passage between said three way catalyst and said NOx absorbent; and secondary air control means for controlling amounts of secondary air fed from said first secondary air supply means and said second secondary air supply means to maintain the air-fuel ratio of the exhaust gas flowing into said three way catalyst at a rich air-fuel ratio which is larger than an air-fuel ratio of said first mentioned rich air-fuel mixture and to maintain the air-fuel ratio of the exhaust gas flowing into said NOx absorbent at a lean air-fuel ratio. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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Specification