| 摘要 |
An exhaust valve arrangement for a large slow-running two-stroke uniflow diesel engine with crossheads and a with an exhaust valve (l) that can open between a closed and an open position for scavenging of the combustion chamber a gas spring (123) operatively connected to said exhaust valve (1), a hydraulic actuator (109) being operatively connected the exhaust valve (1), the hydraulic actuator (109) comprising a plunger (10') received in a bore (6) and defining an actuation chamber ( 60) between said bore ( 6) and said plunger (l0' ) for carrying out said opening stroke when said actuation chamber (60) is pressurized and for allowing said exhaust valve (l) to carry out the return stoke when said actuation chamber (60) is connected to tank, a source of high-pressure hydraulic fluid, a tank, an electronically controlled hydraulic control valve (117, 120) operatively connected to an electronic control unit (115), the actuation chamber ( 60) being selectively connectable to said source of high-pressure hydraulic fluid or to said tank via said electronically-controlled hydraulic control valve (117, 120), a hydraulic passageway (80, 85) connecting said actuation chamber (60) to said electronically-controlled hydraulic control valve (117,120), said hydraulic passageway (80,85,280) including a flow restriction (19) that is active during the last part of the opening stroke and the first part of the return stroke of said exhaust valve (1), and a bypass arrangement (117,121,195,197) for bypassing said flow restriction (19) in said hydraulic passageway (80, 85) at least during the first part of said return stroke. |
