The structure and working principle of a two-cylinder four-stroke single-piston hydraulic free piston engine(HFPE) were introduced. The basic vibration equation of free piston assembly(FPA) was established based upon the energy conversion between the injected fuel and the friction together with the load. Both the theoretical and numerical results show that the vibration system of FPA is a nonlinear conservative autonomous system in one cycle. The FPA vibration is symmetric with constant amplitude when FPA is only driven by the compression pressure in the compression accumulator and that in the combustion chamber. When considering the friction and load, FPA could still achieve a stable vibration after a few cycles' adjustment whether the input energy is equal to the consumed energy or not. The vibration characteristics are different when FPA vibrates in the compression stroke and the expansion stroke, which is the unique feature of the single-piston HFPE.

针对柱塞泵在应用过程中流体运动不稳定的问题,设计一种新型稳流柱塞泵阀芯结构。四缸四冲程式柱塞泵由电动机提供动力带动偏心轮机构转动,将电动机的旋转运动转化为柱塞的往复运动,给水加压。选用石墨/ZTA陶瓷基复合材料作为缸体材料来解决水环境下柱塞泵易磨损问题。针对其结构设计、材料选型以及工作原理进行论述。

1背景资料1.1船舶情况某油船船龄6年,配备3台MAN B&W 6L23/30型副机,该机型为直列式、四冲程、增压中冷、四气阀,额定转速720 r/min,额定功率750 k W。拆卸和安装缸盖螺母、连杆大端螺栓、主轴承螺栓等均采用液压拉伸器,液压紧固压力为750 bar(1 bar=0.1MPa),最大紧固压力为775 bar。

柴油机是船舶的心脏,气阀是柴油机的重要零部件之一,一旦漏气,将影响柴油机的正常运转,现代柴油机的强化程度较高,本文研究的中速大功率船用柴油机,气缸直径为330mm,四冲程,活塞行程为440mm,最高爆发压力可达17.5MPa,燃烧发火温度瞬间达到1800℃,一旦阀线局部漏气,在高温、高压燃气吹蚀下,很快就可将阀面吹蚀,作为船舶推进用柴油机,就需停机检修.