Patent ID: 7591244

Claim:
A method for controlling the intake valves ( 41 , 42 ) and exhaust valves ( 43 , 44 ) of the cylinders ( 1 ) of an internal combustion engine which is capable of operating either in positive mode or in braking mode, said engine comprising control means ( 6 ) for said valves ( 4 ), said control means being adapted to establish a first four-stroke timing sequence of the valves of each cylinder for the positive mode of said engine and a second two-stroke timing sequence of said valves for the braking mode of said engine, said control means piloting said valves so that at least a first exhaust valve ( 43 , 44 ) of each cylinder ( 1 ) is opened prior (t 0 ) to a first instant (t 1 ) when the piston ( 2 ) of said cylinder reaches its top dead center position (TDC), characterized in that, during said second timing sequence, said exhaust valves ( 43 , 44 ) are piloted by said control means ( 6 ) so that: said first exhaust valve ( 43 , 44 ) is kept in an open state with a first lift (L 1 ) and for a first predetermined period of time (Δt 1 ), prior to said first instant (t 1 ), and at least an exhaust valve ( 43 and/or 44 ) is kept in an open state, with a second lift (L 2 ) higher than said first lift and for a second predetermined period of time (Δt 2 ), after said first instant, wherein during said second timing sequence, said control means ( 6 ) close said first exhaust valve ( 43 ) after said first period (Δt 1 ), and open a second exhaust valve ( 44 ) before said first instant (t 1 ), said second valve being kept in its open state (L 2 ) during said second predetermined period of time (Δt 2 ).