| 摘要 |
PURPOSE:To prevent a false decision by deciding the operation of EGR to be such a condition that it can be conducted when the intake air flow is more than a designated value and the intake air quantity for one stroke of an engine is less than a designated value. CONSTITUTION:Negative pressure from an intake tube negative pressure take-out port 34 is introduced into a diaphragm chamber 27 of a diaphragm device 25 for driving a valve element 24 of an EGR valve device 20 through a temperature sensing valve 32 adapted to open when water temperature is more than a designated value and a negative pressure control valve 30 operated in response to exhaust pressure. A micro-computer 50 to which detection values of an air flow meter 3, an engine speed sensor 56, a water temperature sensor 57, and a temperature sensor 59 disposed in an EGR passage 13 are input is adapted to diagnose the operation of EGR to be in such a condition that it can be conducted according to a detection value of the temperature sensor 59 under a condition that when the intake air flow detected by the air flow meter 3 is more than a designated value and the intake air quantity for one stroke of an engine, which is obtained by dividing the intake air flow by a number of revolutions, is less than a designated value. |
