| 摘要 |
PROBLEM TO BE SOLVED: To further improve the accuracy of estimating the oxygen storage capacity of an exhaust gas purifying catalyst mounted in an exhaust passage of an internal combustion engine.SOLUTION: When estimating the oxygen release amount of the catalyst in a period from varying the air-fuel ratio to be rich on the upstream side of the catalyst in the state of filling oxygen in the catalyst to actualizing a variation in the air-fuel ratio to be rich on the downstream side, a control device for the internal combustion engine determines a delay time to varying the air-fuel ratio to be rich on the upstream side of the catalyst after filling the oxygen in the catalyst, depending on how the air-fuel ratio of gas oscillates in one cycle of the internal combustion engine. When estimating the oxygen storage amount of the catalyst in a period from varying the air-fuel ratio to be lean on the upstream side of the catalyst in the state of releasing the oxygen from the catalyst to actualizing a variation in the air-fuel ratio to be lean on the downstream side, the control device determines a delay time to varying the air-fuel ratio to be lean on the upstream side of the catalyst after releasing the oxygen from the catalyst, depending on how the air-fuel ratio of the gas oscillates in one cycle of the internal combustion engine.SELECTED DRAWING: Figure 3 |
