| 摘要 |
PURPOSE:To enhance the controlability of air-fuel ratio when the operating condition of an engine is shifted into the idle condition, by making the maximum displacement of an air-fuel ratio control actuator, upon air-fuel ratio feedback control, different between the idle condition and the off-idle condition. CONSTITUTION:In the off-idle condition, a changeover switch 26 delivers the output signal of a second maximum current setting unit 22 to an air-fuel ratio control actuator 12 under the control of a condition discriminator 24. Therefore, the actuator 22 is controlled with a feedback signal which is integrated with the corresponding integration constant by an integrator 20 and is limited at its upper limit by the maximum current value I2 from the setting unit 22. Next, when the operating condition is shifted into the idle condition, the output signal of a first maximum current setting unit 18 is delivered to the actuator 12 so that the maximum current value is forcedly dropped to the maximum current value I1 suitable for the idle condition. From this time point, the actuator 12 is controlled with a feedback control signal which is integrated with the corresponding integration constant suitable for the idle condition by an integrator 16. Accordingly, the exact feedback control may be carried out even just after the shift into the idle condition. |
