| 摘要 |
PROBLEM TO BE SOLVED: To provide an air-fuel ratio control device of an engine, capable of estimating an oxygen storage quantity of a second catalyst in fuel cut, without using an expensive wide area air-fuel ratio sensor. SOLUTION: This air-fuel ratio control device of the engine has a first catalyst 21, the second catalyst 25, a front air-fuel ration sensor 22, and an air-fuel ratio control means for controlling the air-fuel ratio so that an oxygen storage quantity estimation value of this first catalyst coincides with a target value, by estimating an oxygen storage quantity of the first catalyst based on output of this front air-fuel ratio sensor, and has a second catalyst oxygen storage quantity estimating means 11 estimating the oxygen storage quantity of the second catalyst 25 in the fuel cut, and air-fuel ratio enriching processing means 11 and 6 performing air-fuel ratio enriching processing based on the oxygen storage quantity estimation value of this second catalyst 25 when recovering the fuel cut. COPYRIGHT: (C)2008,JPO&INPIT
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