Analysis upon fuel injection quantity variation of common rail system for diesel engines

Liyun Fan,Yun Bai,Xiuzhen Ma,Enzhe Song 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.7

Fuel injection quantity variation of common rail system has effect on the stability and reliability of diesel engines. For purpose of investigating the influence rule and mechanism of fuel injection quantity variation caused by parameters, taking account of the influence of fuel physical properties on dynamic injection characteristics of the system, a bond graph model of common rail injector has been proposed based on bond graph methodology and the state equations of the system are obtained. Comparisons between calculated fuel injection quantities by the numerical model and experimental measurements at different rail pressures and injection pulse widths indicate that the developed model can reasonably predict the fuel injection quantity characteristic of the system. Fuel injection quantity variation characteristics caused by the parameters of common rail injector have been analyzed in entire operating conditions. The selected parameters are delivery chamber diameter, needle seat semi-angle, needle cone semi-angle, ball valve seat semi-angle, nozzle hole diameter, inlet orifice diameter and outlet orifice diameter. The variation rules of quantitative percentages are obtained by quantitative analysis upon fuel injection quantity variation influential factors. It is concluded that ball valve seat semi-angle, nozzle hole diameter, inlet orifice diameter and outlet orifice diameter have the most significant effect on fuel injection quantity variation, and the followed are delivery chamber diameter and needle seat semi-angle. In addition, needle cone semi-angle also results in the variation of fuel injection quantity, but the effect is insignificant.

Research on effects of key influencing factors upon fuel injection characteristics of the combination electronic unit pump for diesel engines

Liyun Fan,Quan Dong,Chao Chen,Yun Bai,Wensheng Zhao,Xiuzhen Ma 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.10

A numerical model of the combination electronic unit pump (CEUP) fuel injection system was developed in AMESim environment. The effects of five key influencing factors, including cam profile velocity, plunger diameter, length of high pressure fuel pipe, inner diameterof high pressure fuel pipe and nozzle flow rate on injection characteristic parameters, were analyzed by using the developed numericalmodel. On the basis, a correlation analysis between the influencing factors and injection characteristics was performed by usingthe design of experiments (DoE) method, and the influences of these factors were quantized accordingly. Relevant results show that boththe single influencing factor and the interaction among these factors correlates with the injection characteristics, and the correlation representsa complex law with the cam rotational speed. The effect of plunger diameter on the injection pressure, cycle fuel injection quantityand injection duration is the most obvious, especially at a cam rotational speed of 500 r/min and the correlation coefficient is up to 0.82. The length of high-pressure pipe (HP pipe) has the most obvious influence on the coefficient of fuel feeding at cam rotational speed of500 r/min and 800 r/min, and the correlation coefficient is negative. Overall, the independent influence of the factors is more significantthan the combined influence of various factors. The CEUP fuel injection system is a complicated multi-input multi-output (MIMO)nonlinear system in fact.

Dynamic performances analysis and optimization of novel high-speed electromagnetic actuator for electronic fuel injection system of diesel engine

Peng Liu,Liyun Fan,Wei Zhou,Xiuzhen Ma,Enzhe Song 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.8

High-speed electromagnetic actuator (HEA) is the key component of Electronic fuel injection system (EFIS) of diesel engine, its dynamic performances have a significant impact on the control accuracy and flexible control law of fuel injection. In order to obtain the higher dynamic response speed, lower power consumption, higher safety and reliability, a novel HEA with permanent magnet (NPMHEA) was proposed based on the principle of parallel magnetic circuit in this paper. Then the simulation models of HEA coupling of magnetic field, electric circuit and mechanical motion were developed by the method of time-stepping finite element, and their precisions were verified by experiment. By the comparative analysis, influence rules of key parameters on the dynamic performances of HEA have been established. In addition, the multi-objective optimization of NPMHEA based on response surface methodology and Genetic algorithm (GA) was carried out and the Pareto optimal solution set was obtained. It is concluded that there are contradictions between objectives for the Pareto optimal solutions; considering the whole performances, the optimal solution is determined for which the peak current, the peak pulse and the hold current reduce by 20.5 %, 7.8 % and 43.9 %, respectively, and the actuation response speed quickens by 11.9 %, significantly reducing the power consumption and coil loss and improving the dynamic response speed of HEA. It decisively provides certain theoretical guidance for the design and optimization of HEA.

STABILITY ANALYSIS UPON HIGH-PRESSURE COMMON RAIL FUEL INJECTION SYSTEM UNDER MULTIPLE INJECTION MODES

Qi Lan,Yun Bai,Xiuzhen Ma,Liyun Fan,Jing Xu 한국자동차공학회 2021 International journal of automotive technology Vol.22 No.2

Fuel injection stability of high-pressure common rail fuel injection system (HPCRFIS) under multiple injection modes is a recognized technical problem. To explain it essentially, a numerical model based on bond graph method, which provides a standardized series of symbol system to describe various components in different physical fields as well as interactive effect analysis tool for different energy categories, was used to investigate the problem. As HPCRFIS is a typical nonlinear system with multi-physical coupling, it is very difficult to analyze system stability directly. Therefore, the system was linearized at typical moments. The system matrix for each typical moment was obtained thereby. To investigate the influential mechanism of system stability deeply, the variations of rank and eigenvalues distributions of state matrices were analyzed. The results show that the rank of state matrices changes abruptly when the needle or control valve moves. In terms of system stability, the oscillation characteristics are subject to the movement of needle or control valve. The ending of the former injection causes the system to show damping oscillation characteristics before the latter injection starts.The motion of control valve makes more contribution to system stability than that of needle, which could be concluded by Lyapunov stability criterion.

Correction strategy of fuel injection quantity during pilot-main injection for common rail system

Yun Bai,Yuanqi Gu,Qi Lan,Liyun Fan,Xiuzhen Ma 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.6

Common rail system is a key technology of energy saving and emission reduction for modern diesel engines. Multiple injection, as one of the most interesting features of common rail system, allows both optimal fuel consumption and exhaust emissions. In order to explore the method for controlling the fluctuation of fuel injection quantity during multiple injection, experiments have been carried out in this paper, focusing on pilot-main injection. The high pressure fuel circuits of the system have been equivalent to a spring-mass vibration system. Comparison with the experiment shows that the proposed fluctuation equation can reasonably predict the fluctuation characteristics of main injection quantity with pilot-main injection interval. The correction control strategy for the main injection quantity fluctuation has been proposed, in which the relative damping coefficient, rail pressure, pilot-main injection interval and main injection pulse width are chosen as the input variables. The experimental results with different rail pressure and main injection quantity show that the fluctuation of injection quantity during pilotmain injection can be controlled effectively by the proposed correction strategy. The maximum average fluctuation of main injection quantity decreases by as much as 44.66 %.