| 摘要 |
PURPOSE:To prevent transient increase of an intake valve, by a method wherein a sub-throttle valve and a shutter valve, opened during failure in operation of a main throttle valve control system, are situated in a bypass passage running around a main throttle valve, and when the shutter valve is in an abnormal state, the opening of the main throttle valve is corrected so as to be decreased. CONSTITUTION:A main throttle valve 10 is situated in an intake passage 8, and a sub-throttle valve 17, operated by an accel pedal 15 through a cable 16 and the like, is situated in a bypass passage 14 situated in a manner to run around the main throttle vale 10. A shutter valve 18, opened by an actuator 19 during failure in operation of the control system of the main throttle valve 10, is located in the bypass passage 14, and the actuator 19 is driven by introducing a pressure signal, controlled by a solenoid valve 20 on the negative pressure side and a solenoid valve 21 on the open air side, to a negative pressure chamber 19a thereof. An abnormality detecting means, detecting abnormality where the shutter valve 18 is brought into an opening state during normal operation, is mounted, and when abnormality of the shutter valve 18 is detected by the means, the opening of the main throttle valve 10 is corrected in a direction in which the opening is decreased.
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