| 摘要 |
PROBLEM TO BE SOLVED: To detect a back flow distinguished from a forward flow by deciding the maximum and minimum points of detection values of an intake air flow, comparing the maximum value with the set comparison value, and when the maximum value is smaller than the comparison value, judging the intake air flow detected between the minimum points before and after the maximum values as the back flow value. SOLUTION: An intake air flow detection signal from a hot-wire air flowmeter which detects the intake air flow regardless of a forward flow or a back flow is input in a variable acceleration operation means 1 and the variable acceleration is operated here. The positive/negative mark change in this variable acceleration is detected by a detection means 2 and after it is detected that the mark of the variable acceleration is inverted from the negative to the positive, whenever the same inversion is detected at the next time, the maximum value of the intake air flow is detected by a maximum value detection means 3. And the comparison value found in the operation means 5 based on an engine operation state and the maximum value are compared by the comparison means 6 and in the case of the maximum value < the comparison value, it is decided in the decision means 7 that the intake air flow detected between the minimum points before and after the maximum value is the back flow value. |
