Patent ID: 6397799
Filing Date: 2002-06-04
Classification: F01L,F02D

Abstract:
A method for controlling a valve lift device associated with an internal combustion engine, which comprises:determining, according to maps, a relative timing angle to be applied to a camshaft and a crankshaft; processing the determined timing angle with a PID-type control; determining, each time an engine enters a stabilized low idle speed, a reference value of the timing angle when a valve lift device is inactivated; taking the reference value into consideration when any later timing angle command is given; and at least one of: pre-establishing, on a test bed, a map of a duty cycle for an opening of a hydraulic valve controlled by the PID of the valve lift device as a function of an engine water temperature, and adjusting the timing angle to be applied as a function of the engine water temperature by modifying the reference value; determining a difference between a timing angle command applied and a command calculated in the pre-establishing step by observing an I term of the PID controlling the valve lift device and storing a value of the I term in an adaptive term; determining a response time of the valve lift device and modifying a proportional term of the PID as a function of the response time; and determining if the relative timing angle of the camshaft and the crankshaft fluctuates when a set point value is stable, and modifying the proportional term of the PID to avoid a fluctuation if the relative timing angle fluctuates.