Patent ID: 8311724

Claim:
A method of controlling an engine system having an internal combustion engine and a turbo charger which is equipped with a turbine arranged in an exhaust passage of the internal combustion engine and a compressor arranged in an intake passage of the internal combustion engine and driven by the turbine, comprising: increasing a valve overlap period during which an intake valve and an exhaust valve of a combustion chamber of the internal combustion engine are both opened as a desired torque of the internal combustion engine increases by advancing an opening timing of the intake valve at a rate which is greater than that of retarding a closing timing of the exhaust valve in a low engine-torque area in which the desired torque of the internal combustion engine is relatively low; and increasing the valve overlap period as the desired torque of the internal combustion engine increases by retarding the closing timing of the exhaust valve at a rate which is greater than that of advancing the opening timing of the intake valve in a high engine-torque area in which the desired torque of the internal combustion engine is relatively high.