Liyun Fan

A study on cycle fuel injection quantity variation for a diesel engine combination electronic unit pump system

A new fuel injection equipment, combination electronic unit pump was developed to make diesel engines compliant with China’s new laws on emissions. Combination electronic unit pump system is a complex assembly constituting of mechanical, hydraulic, and electrical magnetic components. Combination electronic unit pump system includes several electronic unit pumps and mechanical injectors. Cycle fuel injection quantity variation influences product performance and defines its quality of qualification. A numerical model of the combination electronic unit pump system was developed in AMESim environment to create a design tool for engine application and system optimization. Simulated results obtained from this numerical model were validated through experimental tests conducted under the conditions same as numerical model. The results are quite encouraging and consistent with model predictions. Influences of parameters, including variations in supply fuel pressure, cam velocity, plunger-matching clearance, peak control current, anchor residual clearance, valve-matching clearance, valve lift, injector opening pressure, nozzle-flow coefficient, and injector needle lift, on cycle fuel injection quantity variation were analyzed in AMESim simulation environment and verified through experiments. The quantitative percentage indexes of the influence of injector characteristic, valve characteristic, plunger characteristic, and low-pressure supply fuel characteristic parameters on cycle fuel injection quantity variation range from 44% to 34%, 20% to 35%, 32% to 19%, and 4% to 12%, respectively, at a cam rotational speed of 500–1300 r/min.

Research on key factors and their interaction effects of electromagnetic force of high-speed solenoid valve.

Analysis consisting of numerical simulations along with lab experiments of interaction effects between key parameters on the electromagnetic force based on response surface methodology (RSM) has been also proposed to optimize the design of high-speed solenoid valve (HSV) and improve its performance. Numerical simulation model of HSV has been developed in Ansoft Maxwell environment and its accuracy has been validated through lab experiments. Effect of change of core structure, coil structure, armature structure, working air gap, and drive current on the electromagnetic force of HSV has been analyzed through simulation model and influence rules of various parameters on the electromagnetic force have been established. The response surface model of the electromagnetic force has been utilized to analyze the interaction effect between major parameters. It has been concluded that six interaction factors including working air gap with armature radius, drive current with armature thickness, coil turns with side pole radius, armature thickness with its radius, armature thickness with side pole radius, and armature radius with side pole radius have significant influence on the electromagnetic force. Optimal match values between coil turns and side pole radius; armature thickness and side pole radius; and armature radius and side pole radius have also been determined.

Investigation on the fuel injection quantity fluctuation of a common-rail fuel injection system using response surface methodology:

Variations in the parameters affect the injection characteristics of a common-rail injection system and leads to fluctuation in the fuel injection quantity. This paper is aimed at combining the numerical modelling and design of experiments to investigate the significant effects of the interactions between the common-rail injector parameters on the fluctuation in the fuel injection quantity using response surface methodology. A numerical model of a common-rail injector was developed. The model was validated by comparing simulation results with experimental measurements, which showed that it can accurately predict the fuel injection quantity of the system. The design of experiments was performed using a two-level five-factor D-optimal design. The factors studied were the pre-tension of the control valve spring, the diameter of the outlet orifice, the diameter of the inlet orifice, the needle lift and the diameter of the nozzle holes. A quadratic response surface model was suggested by means of partial least-squares regression analysis. The distribution of the standardized residuals, the relation between the predicted fluctuation and the observed fluctuation in the fuel injection quantity, the coefficient R2 of determination and the adjusted coefficient R adj 2 of determination for the response surface model were analysed, which demonstrated the significance of the model. Analysis of the F value and the p value for the model terms at the 95% confidence level revealed that the interactions between the control valve spring pre-tension and the nozzle hole diameter, between the outlet orifice diameter and the nozzle hole diameter, between the inlet orifice diameter and the nozzle hole diameter and between the needle lift and the nozzle hole diameter had significant effects on the fluctuation in the fuel injection quantity of the system. Furthermore, the significant effects of the interactions between these parameters were analysed in detail.

Nonlinear Modeling and Analysis of Pressure Wave inside CEUP Fuel Pipeline

Operating conditions dependent large pressure variations are one of the working characteristics of combination electronic unit pump (CEUP) fuel injection system for diesel engines. We propose a precise and accurate nonlinear numerical model of pressure inside HP fuel pipeline of CEUP using wave equation (WE) including both viscous and frequency dependent frictions. We have proved that developed hyperbolic approximation gives more realistic description of pressure wave as compared to classical viscous damped wave equation. Frictional effects of various frequencies on pressure wave have been averaged out across valid frequencies to represent the combined effect of all frequencies on pressure wave. Dynamic variations of key fuel properties including density, acoustic wave speed, and bulk modulus with varying pressures have also been incorporated. Based on developed model we present analysis on effect of fuel pipeline length on pressure wave propagation and variation of key fuel properties with both conventional diesel and alternate fuel rapeseed methyl ester (RME) for CEUP pipeline.

Investigation on Electromagnetic Models of High-Speed Solenoid Valve for Common Rail Injector

A novel formula easily applied with high precision is proposed in this paper to fit the - curve of soft magnetic materials, and it is validated by comparison with predicted and experimental results. It can accurately describe the nonlinear magnetization process and magnetic saturation characteristics of soft magnetic materials. Based on the electromagnetic transient coupling principle, an electromagnetic mathematical model of a high-speed solenoid valve (HSV) is developed in Fortran language that takes the saturation phenomena of the electromagnetic force into consideration. The accuracy of the model is validated by the comparison of the simulated and experimental static electromagnetic forces. Through experiment, it is concluded that the increase of the drive current is conducive to improving the electromagnetic energy conversion efficiency of the HSV at a low drive current, but it has little effect at a high drive current. Through simulation, it is discovered that the electromagnetic energy conversion characteristics of the HSV are affected by the drive current and the total reluctance, consisting of the gap reluctance and the reluctance of the iron core and armature soft magnetic materials. These two influence factors, within the scope of the different drive currents, have different contribution rates to the electromagnetic energy conversion efficiency.

Research on Electronic Control Unit of Electronic Unit Pump Fuel Injection System for Diesel Engines

Electronic Unit Pump (EUP) system is a fuel injection system with high injection pressure which can be applied to control fuel quantity and injection timing flexibly. The EUP fuel injection system has prospective application in medium or heavy diesel engines. The research on electronic control unit which based on EUP fuel injection system for diesel engines was introduced. Pulse signal was collected by the input capture function, and then the average speed was calculated by the rolling average method. Cylinder detection and accurate timing were realized with camshaft and crankshaft signals. The fast and accurate control for EUP fuel injection system was realized with the Peak&Hold drive and Solenoid valve closure start-point control. Experimental results show that the control unit can meet the requirements of EUP system.

Influential factors’ correlation analysis upon common rail system fuel injection quantity for diesel engines

The coherence of the fuel injection quantity determines the working stability of the common rail system. The variations in the parameters of the common rail injector have significant influence on coherence of the fuel injection quantity of the system. The bond graphs for the main components of the common rail injector were proposed, respectively, based on the bond graph methodology in this article. The fuel injection quantities of the system at different rail pressures and injection pulse widths had been obtained by numerically solving and programming the obtained state equations in MATLAB. The predicted results of the fuel injection quantity by the model are in excellent agreement with the experimental measurements which were obtained from a test bench. Through the correlation analysis of the influential factors on the fuel injection quantity, the correlation coefficients between the fuel injection quantity and the single influential factor and quadratic influential factor at different rail pressures and injection pulse widths were obtained, respectively. Moreover, the variation characteristics of correlation between the fuel injection quantity and its influential factors had been analyzed in detail. The results show that the nozzle hole diameter and the inlet orifice diameter are the main influential factors on the fuel injection quantity among the selected parameters. The quadratic factors under the action of the parameter itself and the quadratic factors under the interaction between the delivery chamber diameter and nozzle hole diameter, needle seat semi-angle and needle cone semi-angle, nozzle hole diameter and inlet orifice diameter and inlet orifice diameter and outlet orifice diameter have significant effect on the fuel injection quantity, and they are the main influential factors on the fuel injection quantity among the quadratic factors.

Fuel Injection Quantity Fluctuation Prediction of Common Rail System Based on Bond Graph Model

Common rail injection system (CRIS) is an advanced technology which meets the stringent emission standards of diesel engines and satisfies consumer demand for better fuel efficiency and increased power. The coherence of fuel injection quantity is the key injection characteristic for CRIS to match diesel engines successfully. As a critical component for CRIS, the variation of injector characteristic parameters has significant influence on the coherence of fuel injection quantity of the system. In this paper, combining numerical modeling and design of experiments, the response predicted relation between fuel injection quantity fluctuation of CRIS and its influence factors had been investigated. A numerical model of common rail injector was presented for the purpose of creating a tool for simulation experiments. The model is developed using power bond graph method, which is a modeling method that has shown its superiority in modeling systems consisting of sub-models from several energy domains in a unified approach. Experiments were conducted at the same model conditions to validate the model. The results are quite encouraging and in agreement with model predictions, which imply that the model can accurately predict the fuel injection quantity of CRIS and it can be used to simulation and design experiments. Experiments were designed using D-optimal method in which the characteristic parameters of common rail injector were chosen as design factors and the fuel injection quantity fluctuation was selected as the response. The fuel injection quantity fluctuation responses at different design factor levels were obtained using the developed numerical model which had been validated. A regressive prediction model of fuel injection quantity fluctuation was suggested according to the simulation experiments by means of partial least-squares regression (PLR) analysis. Analysis of variance, normal distribution of standardized residuals and relation between observed and predicted fuel injection quantity fluctuation for the regressive prediction model were analyzed which demonstrate the favorable goodness of fit and significance of the regressive model to predict fuel injection quantity fluctuation of the system. By changing design factor levels, the comparisons between numerical results of the bond graph model and the predicted fuel injection quantity fluctuation of the regressive prediction model were conducted. Results show that the regressive prediction model can reliably predict the fuel injection quantity fluctuation caused by the variation of characteristic parameters of common rail injector. Research results of this paper can provide novel ideas to predict fuel injection quantity fluctuation and a theoretical guidance for design and parameters optimization of CRIS.Copyright

Experimental Study on Fuel Injection Characteristics of Electronic Unit Pump System for Marine Diesel Engines

Fuel injection characteristics of electronic unit pump (EUP) system for marine diesel engines were researched. Through the comparison analysis of its experimental study on pump bench, conclude EUP characteristics mechanism, include the different characteristic curves of pump pressure, injector pressure, fuel injection quantity and hydraulic delay at different working conditions. To some degree, it can provide theory support for the designing of the EUP system, and offer valuable advice to match different engines.

Numerical Simulation of Electromagnetic Force of High-Speed Solenoid Valve for Diesel Engine Electronic Unit Pump

Electronic unit pump (EUP) is a time controlled fuel injection system which is used on diesel engine to meet emissions regulations and improve the fuel economy. High-speed solenoid valve is one of its key components. Its rapid response has an effect on the precise control of fuel injection quantity and fuel injection timing. The rapid response of solenoid valve is determined by the electromagnetic force. The simulation model of high-speed solenoid valve is established in Ansoft environment. The accuracy of the model is validated by comparing to the experiment results and the maximum deviation is 9%. The parameters change of iron core, winding, armature, assembly and control on the influence of the electromagnetic force have been studied by simulation model. It is concluded that the excitation coil turns, working air gap, drive current and armature thickness are the main influence factors on electromagnetic force.