| 摘要 |
The objective of the present invention is to enable the timing for closing an exhaust valve to be changed by means of a simple configuration suitable for an internal combustion engine for a ship, and to adapt the characteristic of the internal combustion engine to the operating state. This exhaust valve drive device (1) is equipped with: a piston (7) provided on an exhaust valve (5) of an internal combustion engine; a cylinder (9) in which the piston (7) is housed; an oil pressure supply device (13) that is driven by a cam (35) and intermittently supplies oil pressure to the cylinder (9) with a prescribed valve-opening timing, thereby pressing the piston (7) and opening the exhaust valve (5); an air spring device (15) that biases the exhaust valve (5) in the direction of closing; a convex part (7a), which is formed on the top surface of the piston (7), and the top surface area of which is smaller than the cross-sectional surface area of the piston (7); a concave part (9a), which is formed in the ceiling surface of the cylinder (9), and into which the convex part (7a) is inserted with a gap therebetween when the piston (7) rises; an actuator (17) that changes the depth of the concave part (9a); and a control device (19) that controls the actuator (17). |
