Method of operating an internal combustion engine
A method is disclosed for operating an internal combustion engine of the type having an engine cylinder (10) with a reciprocating piston (20), first (24) and second (22) intake ports for admitting gas from an ambient air supply into the engine cylinder, first (14) and second (12) intake valves each arranged between a respective one of the intake ports and the engine cylinder, a non-return valve (32) arranged in the second (22) of the intake ports at a distance from the second intake valve (12) and oriented to allow gas to flow only towards the engine cylinder (10), and a variable valve actuating system for controlling the opening and closing of at least the second intake valve.; In the method of the invention, in at least one operating mode of the engine, the second intake valve (12) is opened and closed, while the cylinder (10) is fully isolated from the ambient air, to permit gas transfer between the cylinder and an auxiliary chamber (30) temporarily defined by the part of the second intake port (22) lying between the second intake valve (12) and the non-return valve (32). The second intake valve (12) is opened at a time when the pressure in the auxiliary chamber (30) is greater than the pressure of the ambient air supply such that no gas escapes past the non-return valve (32).
MA THOMAS TSOI-HEI
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