| 摘要 |
PROBLEM TO BE SOLVED: To keep good air-fuel ratio accuracy regardless of response of an evaporation concentration sensor disposed on an intake side, with regard to a vaporized fuel treating device for an internal combustion engine. SOLUTION: Purge controlled variables are slightly increased while a feedback control of a fuel injection amount is performed based on an exhaust air- fuel ratio (step 102). A virtual air-fuel ratio that is implemented when the feedback control is not executed, is calculated (step 104). Allowable purge controlled variables in which the virtual air-fuel ratio reaches an allowable air-fuel ratio, is detected (steps 106, 108). The purge controlled variables are changed stepwise by the allowable purge controlled variables (step 110). Reducing correction of the fuel injection amount is performed based on the output from the evaporation concentration sensor (step 112). The response of the evaporation concentration sensor is estimated depending on the output behavior (an noninversion period) of an exhaust O<SB>2</SB>sensor (step 116). A guard is set to a change speed of the purge controlled variables based on the response (step 118). COPYRIGHT: (C)2004,JPO
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