Patent ID: 6983725

Claim:
Exhaust valve mechanism in an internal combustion engine, comprising at least one exhaust valve ( 14 ) in each cylinder, a rocker arm shaft ( 3 )-mounted rocker arm ( 2 ) for each cylinder for operating the exhaust valve, a cam shaft ( 6 ) with a cam element ( 5 ) for each rocker arm, said cam element cooperating with motion transmitting means ( 4 ) at one end of the rocker arm, a first piston-cylinder device ( 8 ) disposed between an opposite end of the rocker arm and the exhaust valve, said first piston-cylinder device ( 8 ) having a first cylinder chamber ( 9 ) in said opposite rocker arm end, a hydraulic circuit ( 20 ) for supplying and draining off pressure fluid to and from said cylinder chamber, and a piston ( 10 ) disposed in said cylinder chamber, said piston ( 10 ) being biased towards the exhaust valve when pressure fluid is supplied to the cylinder chamber, characterized in that the rocker arm ( 2 ) is provided with a second piston-cylinder device ( 40 ) on the same side of the rocker arm shaft as the first piston-cylinder device ( 8 ), said second piston-cylinder device ( 40 ) having a second cylinder chamber ( 41 ) communicating with the first cylinder chamber and housing a second piston ( 42 ) which, upon supply of pressure fluid to the second cylinder chamber, is biased in a direction from the exhaust valve, and that a second rocker arm ( 46 ) mounted on a rocker arm shaft has an end ( 53 ) acting against the second piston and an opposite end with motion-transmitting means ( 49 ), which cooperate with a cam element ( 50 ) on a cam shaft ( 6 ).