Internal combustion engine with wall masking the curtain area of the intake valves

摘要

A spark ignition four stroke internal combustion engine comprises two intake valves and two exhaust valves (7, 70) for each cylinder, arranged around a central spark plug and it is provided with means for varying the lift of the intake valves (7) between a zero value and a maximum value H. A masking wall (M) which masks the curtain area of the intake valves (7) on one side facing towards the exhaust valves is provided in the combustion chamber (2) associated to each cylinder. The axis (7a) of each intake valve (7) is inclined with respect to the axis (X) of the respective engine cylinder by an angle (A) not exceeding 12° and the abovementioned masking wall (M) has along the seat of each intake valve (7) a height h in the direction parallel to the axis (7a) of the intake valve (7) which is comprised between 0.1 and 0.5 times, extremes excluded, the abovementioned maximum value H of the lift of the intake valves (7).