一、前言在作为船用主发动机使用的低速和中速柴油机上很早以前就开始使用低质油作燃料了。最近,随着这些柴油机使用的燃料的进一步低质化,作为辅助发动机使用的中速柴油机上也与主发动机一样,出现了使用低质燃料的倾向。船用柴油机面临的燃料进一步低质化,燃烧效率的改进,和对使用大型排气阀的二冲程单流式柴油机重新进行评价的形势,都要求提高燃料喷射系统、排气阀的性 I. INTRODUCTION Low-quality oils are used for fuel very early on low- and medium-speed diesel engines used as the main marine engines. Recently, with the further reduction in the quality of fuels used in these diesel engines, medium-speed diesel engines used as auxiliary engines also have a tendency to use low-quality fuel as the main engine. The further deterioration of the fuel quality of marine diesel engines, the improvement of combustion efficiency, and the reevaluation of two-stroke single-flow diesel engines using large exhaust valves require improvement of the fuel injection system and exhaust valve properties