摘要 |
In an air-fuel ratio feedback control of an internal combustion engine aimed to approximate an air-fuel ratio to a target air-fuel ratio set according to operating conditions of the engine, the feedback control is carried out using the feedback control amount which is computed according to a sliding mode control, having a deviation between the target air-fuel ratio and the detected air-fuel ratio detected by the air-fuel ratio sensor set as a switching function. According to the present invention, a simple air-fuel ratio feedback control is carried out according to an accurate sliding mode control with no dispersion for each engine, that is easy to design, and that can be applied generally to any kind of vehicle or engine. Further, by varying the feedback gain depending on operating conditions, by controlling the computing cycle of the feedback control amount, or by performing a Smith dead time compensation control, the influence provided by the dead time element existing in the control object is eliminated, thereby ensuring the response characteristic and stability of the control system.
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