| 摘要 |
PROBLEM TO BE SOLVED: To provide a poisoning restoring device for an exhaust sensor, preventing an air-fuel ratio from being set excessively to a rich mixture side or to a lean mixture side during restoring the poisoning of the exhaust sensor. SOLUTION: The poisoning restoring device for the exhaust sensor executes: a normal mode for air-fuel ratio control to make an actual air-fuel ratio detected by the exhaust sensor 38 approximate a target air-fuel ratio; and a poisoning restoration mode for air-fuel ratio control to set an air-fuel ratio at the time when releasing poisoning materials deposited on the exhaust sensor 38, as the target air-fuel ratio at the time when restoring poisoning, compute an actual air-fuel ratio in accordance with the operated condition of an engine 1, and make the actual air-fuel ratio approximate the target air-fuel ratio at the time when restoring poisoning. In the normal mode, it calculates a variation of the supply amount of fuel to be supplied via a fuel supply valve 37 in accordance with a deviation between the detected actual air-fuel ratio and the actual air-fuel ratio found by the computation, and stores it as a learning value according to the operated condition of the engine 1. In the poisoning restoration mode, it corrects the actual air-fuel ratio found by the computation in accordance with the learning value. COPYRIGHT: (C)2009,JPO&INPIT
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