Patent ID: 6209518
Filing Date: 2001-04-03
Classification: F02D

Abstract:
A method of fail-safe controlling an electronically-controlled throttle valve of an internal combustion engine comprising the steps of:setting a target position of a throttle valve disposed in an intake system depending upon engine operation conditions inclusive of a position of an accelerator detected by one accelerator position sensor selected from two accelerator position sensors equipped to said engine;operating said throttle valve to be opened and closed by an actuator so that a position of said throttle valve detected by one throttle position sensor selected from two throttle position sensors equipped to said engine reaches the target position;when either one of said two accelerator position sensors or either one of said two throttle position sensors fails to operate, executing a first fail-safe control operation for controlling the position of said throttle valve by basically using a value detected by the remaining sensor; andin a state where one sensor fails to operate between said two accelerator position sensors or one sensor fails to operate between said two throttle position sensors, interrupting said first fail-safe control operation and, instead, executing a second fail-safe control operation to hold said throttle valve at a predetermined position when an operation for decelerating the engine is detected by a sensor in a system separate from said sensors.