| 摘要 |
PROBLEM TO BE SOLVED: To make the characteristic of an internal combustion engine conform to an operation condition by changing a closing timing of an exhaust valve with a simple constitution suitable for a marine internal combustion engine.SOLUTION: An exhaust valve drive device 1 comprises: a piston 7 provided in an exhaust valve 5 of an internal combustion engine; a cylinder 9 into which the piston 7 is accommodated; a hydraulic supply device 13 driven by a cam 35 to intermittently supply a fluid pressure to the cylinder 9 at a predetermined valve opening timing and to open the exhaust valve 5 by pressurizing the piston 7; an air spring device 15 that energizes the exhaust valve 5 in a valve closing direction; a salient 7a formed on a top face of the piston 7 having a smaller top face part area than the cross sectional area of the piston 7; a concavity 9a formed on a ceiling plane of the cylinder 9 and during ascent of the piston 7, the salient 7a is inserted into the concavity 9a via a clearance; an actuator 17 that changes the depth of the concavity 9a; and a control device 19 for controlling the actuator 17. |
