| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To restrain deterioration of estimating accuracy of an air-fuel ratio of respective cylinders in rapid change of an operation state in a system for estimating the air-fuel ratio of the respective cylinders based on a model associating a detection value of an air-fuel ratio sensor installed at an exhaust aggregate of an engine with a state variable (the air-fuel ratio of the respective cylinders). <P>SOLUTION: An ECU 40 in the cylinder-by-cylinder air-fuel ratio control device resets the state variable when the operation state of the engine 11 is rapidly changed and the cylinder-by-cylinder air-fuel ratio is hardly estimated, and thereby, the air-fuel ratio of the respective cylinders in the present operation state is estimated with the usage of the reset state variable without using the state variable influenced by the past operation state when the air-fuel ratio of the respective cylinder is estimated next, and deterioration of estimating accuracy of the air fuel-ratio of the respective cylinders in rapid change of the operation state is restrained. When the cylinder-by-cylinder air-fuel ratio is constantly hardly estimated, the state variable is always maintained in the state of being reset in the period of the operation state. When the cylinder-by-cylinder air-fuel ratio is transiently hardly estimated, the state variable is reset only in that instant. <P>COPYRIGHT: (C)2008,JPO&INPIT</p> |
