| 摘要 |
PURPOSE:To improve the precision of the air-fuel ratio in transient time by adding the value corresponding to the detection value at each precscribed cycle of the internal pressure in a suction pipe up to this time onto the detection value at this time and setting the added value as standard value and feedback-controlling the standard value according to the detection value of an O2 sensor. CONSTITUTION:A control circuit 20 receives each detection value of an absolute intake pressure sensor 10, crank angle sensor 11, cooling water temperature sensor 12, O2 sensor 14, car speed sensor 16, etc., and controls the air-fuel ratio through a solenoid valve 9 installed into the secondary intake air feeding passage 8 according to the operation state. In the air-fuel ratio feedback control region, the control circuit 20 reads the detection value of the absolute intake pressure sensor 10 at each generation of the interruption signal in a prescribed cycle, and adds the value corresponding to the variation quantity between the average value of the detection value up to the preceding time and the average value of the detection value up to this time onto the detection value at this time. Therefore, the variation of the internal pressure in a suction pipe is estimated, and feedback correction on the basis of the detection value of the O2 sensor 14 is performed, having the above-described estimation value as standard value.
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