Elimination of Fuel Pressure Fluctuation and Multi-injection Fuel Mass Deviation of High Pressure Common-rail Fuel Injection System

The influence of fuel pressure fluctuation on multi-injection fuel mass deviation has been studied a lot,but the fuel pressure fluctuation at injector inlet is still not eliminated efficiently.In this paper,a new type of hydraulic filter consisting of a damping hole and a chamber is developed for elimination of fuel pressure fluctuation and multi-injection fuel mass deviation.Linear model of the improved high pressure common-rail system（HPCRS）including injector,the pipe connecting common-rail with injector and the hydraulic filter is built.Fuel pressure fluctuation at injector inlet,on which frequency domain analysis is conducted through fast Fourier transformation,is acquired at different target pressure and different damping hole diameter experimentally.The linear model is validated and can predict the natural frequencies of the system.Influence of damping hole diameter on fuel pressure fluctuation is analyzed qualitatively based on the linear model,and it can be inferred that an optimal diameter of the damping hole for elimination of fuel pressure fluctuation exists.Fuel pressure fluctuation and fuel mass deviation under different damping hole diameters are measured experimentally,and it is testified that the amplitude of both fuel pressure fluctuation and fuel mass deviation decreases first and then increases with the increasing of damping hole diameter.The amplitude of main injection fuel mass deviation can be reduced by 73%at most under pilot-main injection mode,and the amplitude of post injection fuel mass deviation can be reduced by 92%at most under main-post injection mode.Fuel mass of a single injection increases with the increasing of the damping hole diameter.The hydraulic filter proposed by this research can be potentially used to eliminate fuel pressure fluctuation at injector inlet and improve the stability of HPCRS fuel injection.

48 V微混发动机电动智能冷却系统

在电动附件上应用48 V技术,降低功耗和发动机油耗。比较电动水泵与传统机械水泵能量流的区别,测试电动水泵和机械水泵在不同转速下的功耗,分析新欧洲驾驶循环(new European driving cycle, NEDC)下机械水泵和电动水泵的功耗差异;测试电动风扇在NEDC循环下的功耗;测试评估提高冷却液温度、降低水泵和风扇转速对发动机油耗的影响。结果表明,电动智能冷却系统可以精准稳定地控制发动机冷却液温度,水泵电动化使NEDC循环的水泵功耗降低38%,水温由80℃提高到100℃,NEDC循环电动风扇的功耗降低60%,水泵和风扇功耗降低,水温提升引起的散热量减小,NEDC循环油耗降低3.34%。