Electronic throttle control having throttle sensor failure detecting function and fail-safe function

摘要

In an electronic throttle control for an engine, two throttle sensors are used to detect a throttle opening. When a sensor failure is detected in either of those throttle sensors, a feedback control is executed according to the output of the other normal sensor if any. If both throttle sensors fail or it cannot be determined whether there is any normal sensor, the feedback is stopped and the feedback variables are initialized and a motor control duty is set to -30% or 0% according to the existing accelerator depression. Thereafter, if the throttle sensors are not restored even after a preset determination delay time is over, an electromagnetic clutch and a DC motor are turned off to stop the electronic throttle control. A throttle valve is controlled mechanically for a limp-home running.