Valve timing control system for internal combustion engine

Abstract

A valve timing control system for an internal combustion engine capable of accurately accomplishing valve timing control irrespective of variation of the oil pressure to be applied to an hydraulic actuator. The apparatus comprises an hydraulic actuator for changing an operating angle of a cam of a cam shaft to advance or retard a valve timing in the internal combustion engine, a pump for sending a lubricating oil under pressure to the hydraulic actuator, an oil supply quantity adjusting valve for adjusting a quantity of the lubricating oil to be supplied to the hydraulic actuator, and a control unit for estimating a driving force of the hydraulic actuator on the basis of an oil pressure of the lubricating oil on the downstream side of the pump. The controlled variable for the oil supply quantity adjusting valve is determined on the basis of the estimated value of the driving force of the hydraulic actuator.

Dependencies are inferred from the claim text.