Patent ID: 6513468
Filing Date: 2003-02-04
Classification: F01L,Y10T

Abstract:
A valve timing control system for an internal combustion engine, comprising:sensor means for detecting engine operation states of an internal combustion engine; intake or exhaust cam shafts for driving intake or exhaust valves, respectively, of said internal combustion engine in synchronism with a rotation of a crank shaft of said internal combustion engine; at least one actuator operatively connected to at least one of cam shafts for driving said intake or exhaust valves, respectively; a hydraulic pressure supply unit for feeding a hydraulic pressure to drive said actuator; and control means for controlling the hydraulic pressure fed from said hydraulic pressure supply unit to said actuator in dependence on said operating states of said internal combustion engine while changing a relative phase of said cam shaft relative to said crank shaft, wherein said actuator includes a retarding hydraulic chamber and an advancing hydraulic chamber for setting an adjustable range of said relative phase; a locking mechanism for setting said relative phase to a lock-up position within said adjustable range; and an unlocking mechanism for releasing said locking mechanism in response to a predetermined level of hydraulic pressure fed from said hydraulic pressure supply unit, and said control means restricts control of a valve timing within a predetermined range of a lock-up position in said locking mechanism, wherein restraining said control means not executing steady control, and wherein said control means detects a detected advance angle amount that is a phase difference between phases of said crank shaft and said cam shaft and calculates a target advance angle amount that is valve timing suitable for an operating state of said internal combustion engine not to set said target advance angle amount in a predetermined range of said lock-up position of said locking mechanism in the case in which said control means controls such that said detected advance angle amount substantially coincides with said target advance angle amount.