| 摘要 |
PURPOSE:To make a ternary catalytic converter rhodium act effectively and to favorably conduct a measure to counter exhaust gas by driving a solenoid valve for adjusting venturi negative pressure according to a driving signal based on oxygen concentration in exhaust to control an air-fuel ratio. CONSTITUTION:An engine rotating speed, a throttle valve opening and oxygen concentration in exhaust are input to an electronic control unit 38. Both solenoid valves 35, 37 are driven according to a driving signal composed of pulse wave from the electronic control unit 38. The solenoid valve 35 opens and closes a pressurized air passage 33 to send designated pressurized air to an adjusting chamber 20. The solenoid valve 37 opens and closes an atmospheric air passage 36 to introduce atmospheric air into a venturi negative pressure passage 24 and decreases negative pressure generated at a venturi 4 to designated negative pressure to be introduced into a negative pressure chamber 18. Thus the solenoid valve 37 is driven according to oxygen concentration in exhaust and the solenoid valve 35 is driven according to an engine rotating speed and a throttle valve opening, so that feedback control to a theoretical air-fuel ratio can be accomplished in a wide control range extending over the whole operating region of an engine. |
