| 摘要 |
An air/fuel ratio control system for an internal combustion engine is composed of a wide range oxygen sensor capable of sensing an actual air/fuel ratio from a rich side to a lean side, and a control unit having a reference determining section for determining a desired air/fuel ratio in accordance with engine operating conditions such as engine speed and coolant temperature, and a controlling section for controlling a fuel metering system such as fuel injectors so as to reduce a deviation of the actual air/fuel ratio from the desired air/fuel ratio in accordance with a prescribed control action such as a proportional plus integral control action. The control unit is further provided with a reference discriminating section for determining whether the desired air/fuel ratio is in a rich range or in a lean range, and a feedback control constant adjusting section for adjusting at least one control constant such as a proportional gain and an integral gain in dependence on the determination of the reference discriminating section to enable the controlling section to implement the optimum feedback control over the wide range.
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