LARGE TURBOCHARGED TYPE LOW SPEED TWO-STROKE DIESEL ENGINE AND METHOD OF OBTAINING CHARACTERISTIC OF BUTTERFLY VALVE PROVIDED IN LARGE TWO-STROKE DIESEL ENGINE

摘要

PROBLEM TO BE SOLVED: To know, in a system in which a butterfly valve in a gas exchange system of a large two-stroke diesel engine is controlled in open loop, exact relation between the opening of the valve and the effect on a gas flow rate.SOLUTION: There is provided a method of obtaining the characteristics of a non-linear valve 34, 44 for regulating a flow rate in an exhaust bypass which controllably allows exhaust gas to bypass the turbine 17 of a turbocharger 16. The method comprises: while running an engine, opening the non-linear valve 34, 44 little by little from a fully closed position to a fully open position and measuring scavenging pressure or another suitable engine operating parameter at each position of the non-linear flow regulation valve 34, 44; and/or closing the non-linear flow regulation valve 34, 44 little by little from the fully open position to the fully closed position and measuring the scavenging pressure at each position of the butterfly valve. The method comprises: then recording the respective valve positions and the corresponding measured scavenging pressures; and storing the recorded respective positions and corresponding scavenging pressures.