Patent ID: 6178947
Filing Date: 2001-01-30
Classification: F02D

Abstract:
A control apparatus for an internal combustion engine with an electronically-controlled throttle system having a throttle valve disposed in an induction system and an actuator operating the throttle valve so that an opening of the throttle valve is adjusted to a desired opening, comprising:a duplex throttle-position sensor system having two throttle position sensors each detecting the opening of the throttle valve;a vehicle-deceleration sensor detecting a decelerating condition of the engine and generating a deceleration indicative signal; anda fail-safe system configured to be electronically connected to the two throttle position sensors and the vehicle-deceleration sensor for responding to a failure in at least one of the two throttle position sensors for failsafe purposes; said fail-safe system comprising(1) a first failsafe section which controls the opening of the throttle valve by a sensor signal value from an unfailed throttle position sensor of the two throttle position sensors at a single throttle-position sensor failure mode where one of the two throttle position sensors is failed, to initiate a first failsafe mode,(2) a second failsafe section which inhibits the first failsafe mode in response to the deceleration indicative signal from said vehicle-deceleration sensor during the first failsafe mode and holds the throttle valve at a predetermined default opening, to initiate a second failsafe mode, and(3) a third failsafe section which detects if the sensor signal value from the unfailed throttle position sensor is within a predetermined sensor-abnormality diagnostic criterion range during the second failsafe mode, and unconditionally continues to hold the opening of the throttle valve at the predetermined default opening when the sensor signal value from the unfailed throttle position sensor is out of the predetermined sensor-abnormality diagnostic criterion range.