Electronic Unit Pump Research Articles

Multi-objective Optimization of High-speed Solenoid Valve for Biodiesel Electronic Unit Pump

Background: A larger response delay of a high-speed solenoid valve will cause inaccurate fuel injection timing and imprecise cycle injection quantity, resulting in diesel engine emission and increased fuel consumption. Objective: Biodiesel as an ideal alternative fuel has exceptional advantages in energy conservation, emission reduction, and low-carbon environmental protection; however, matching with Electronic Unit Pump (EUP) and its impacts on solenoid valve operation need to be further studied. Methods: In the present work, a numerical model of EUP fueled with biodiesel was established in an AMESim environment, which was validated by the experiment. Then, combined with the Design of Experiments (DOE) method, key parameters influencing the solenoid valve response delay were predicted: armature residual air gap, spring preload, poppet valve half-angle, valve needle diameter, and poppet valve diameter. Results: taking the response delay time of solenoid valve as targets, multi-objective optimization model for high-speed solenoid valve was established using NSGA-II (non-dominated sorting genetic algorithm-II) genetic algorithm in modeFRONTIER platform. Conclusion: The optimized results showed that the delay time of the solenoid valve closing is reduced by 6%, the opening delay time is reduced by 20.8%, the injection pressure peak is increased by 1.8MPa, which is beneficial to accurate injection quantity and the application of biodiesel in diesel engines.

Experimental study on the influence of injection advance angle to diesel engine equipped with electronic unit pump

The fuel injection advance angle of electronic unit pump fuel injection system has a great influence on the running performance of diesel engine as well as the energy consumption, environmental and global warming issues. For a supercharged diesel engine equipped with electronic unit pump, the influence of injection advance angle on the injection characteristics, specific fuel consumption, combustion characteristics and reliability have been studied in this paper, which has important reference significance for the optimization of injection strategy of diesel engine.

Simulation on plateau power recovery of turbocharged diesel engine matched with electronic unit pump

Aiming at the problem of power reduction of supercharged diesel engine equipped with electronic unit pump in plateau operation, a simulation model is established by using onedimensional software BOOST. Under the condition that the maximum combustion pressure and exhaust temperature are basically unchanged, the variation of maximum power, optimal injection advance angle and excessive air coefficient with inlet absolute pressure at typical speed is analyzed, which has important guiding significance for the control strategy of diesel engine in plateau operation.

Research on the Dynamic Cavitation Flow Characteristics in the Control Valve Region During the Opening Process of the Valve in an Electronic Unit Pump

In this paper, the dynamic evolution of cavitation flow in the solenoid valve area and the flow coefficients during the opening process of the valve in an electronic unit pump (EUP) are studied. Firstly, the pressures of high-pressure fuel and low-pressure fuel, the displacement curve of the control valve, and the flow image in the EUP in the period are obtained by an optical experiment. Then, setting the test results as the boundary conditions, a transient CFD simulation of cavitation flow in the valve region during the opening process including rebounds is carried out using dynamic mesh technology. Then the evolution and forming mechanism of cavitation during the process are analyzed. Cavitation is affected by the jet from the valve port which varies with the pressure differential, the geometry of the domain and the movement of the valve. By comparing with the mass flow rate, velocity coefficient, area coefficient and flow coefficient under conditions without cavitation and without rebound, it is found that cavitation can increase the velocity of the fuel, but significantly reduce the effective flow area, which finally affects the flow capacity of the EUP.

Effect of EUP Injection Parameters on the Combustion Characteristics of Diesel Engine

With the increasingly stringent requirements for energy conservation and emission re-duction of diesel engine, electronic control of diesel fuel injection system is necessary. EUP (elec-tronic unit pump) can precisely control the fuel injection process which can reduce the exhaust emission and fuel consumption effectively. In this paper a EUP diesel engine is used as the research object. Through the combination of simulation and experiment, the effect of injector diameter and injection timing on the combustion of the engine is studied. The results show that the above param-eters have an important effect on the gas mixture formation and combustion process of the diesel engine in the cylinder. By selecting the appropriate parameters, the optimized diesel engine can meet the non-road national stage III emission regulation.

Experimental investigation of dwell time characteristics in high-pressure double-solenoid-valve fuel injection system

The double-solenoid-valve fuel injection system consists of an electronic unit pump and an electronic injector. It can realize the separate control of fuel supply and injection and has the advantages of adjusting pressure by cycle and flexible controlling of the injection rate. The interval angle between the pilot and main injection directly affects the action degree and the characteristics of two adjacent injections, affecting engine performance. This work realizes multiple injection processes on the test platform of a high-pressure double-solenoid-valve fuel injection system, with maximum injection pressure reaching 200 MPa. In this study, the interval between driven current signal of pilot injection termination and that of main injection initiation is defined as the signal interval (DT1), whereas the interval between pilot injection termination and main injection initiation is defined as the injection interval (DT2). The differences between the signal and the injection intervals are calculated, and the variation rule of the difference with respect to the signal interval is analyzed. Results show that the variation rule of the difference with the signal interval first decreases, then increases, and finally decreases. The variation rule of the delay angle from the start of needle movement to the start of fuel injection is found to be the root cause of this rule. The influence of the injection pressure on needle deformation and fuel flow rate of the nozzle results in the variation rule. In addition, the influence of the cam speed, temperature, and pipe length on the difference between the signal and injection interval is determined. This research provides guidance for an optimal control strategy of the fuel injection process.

Effects of Control Valve's Structure Parameters on the Circulation Characteristics for an Electronic Unit Pump

The control valve is an essential component of electronic unit pump (EUP) fuel injection systems; it controls the flow rate with high-precision electrical signals. Thus, high precision and flexibility are required in the working process of a fuel injection system. The flow capacity (indicated by mass flow rate) of a control valve is an important technical indicator in the discharge of EUP fuel injection systems. In this study, the transient flow characteristics within control valve during the discharge of an EUP were evaluated using a computational fluid dynamics (CFD) approach. Three essential structural parameters of EUP control valve were investigated, and their effects on circulation characteristics were evaluated. The variation trends were observed, and the changes in significant physical parameters and crucial physical field distributions were analyzed. During the investigation, the visualization of internal flow of control valve provided more detailed information of flow fields. This study shows the effect of each parameter on flow characteristics and indicates that cavitation is the lowest for the case of 0.20 mm valve core lift; the length of slit is the shortest for the case of 7 mm seal diameter, therefore, the mass flow rate of export is the highest; at 139 deg seal cone angles, fuel velocity is the highest, therefore, 139 deg is the best seal cone angle.

Model based calibration for improving fuel economy of a turbocharged diesel engine

Fuel economy is the key performance for the vehicle besides emission, which has been compulsory controlled by the legislation. For the electronic controlled Diesel engines, the mentioned properties could be satisfied not only by engine design but also by engine performance tuning. Fuel economy may be influenced by many coupled factors, such as injection timing, speed, load and under the limitation of cylinder peak pressure and exhaust temperature. To achieve a high efficient calibration, a model based calibration was performed on a four cylinder electronic unit pump Diesel engine with exhaust gas recirculation. The objective of the study is to solve the complexity of the interactions among the engine running parameters and the best fuel economy performance in order to meet under the restriction of NOx emission performance. The study was carried out in four stages. First, the experiment design has been proposed to identify designed experiment operating points and weighting factors. Second, two-stage statistical engine responses and boundary models have been established. Third, the global optimization and European steady-state cycle operating point optimization have been carried out. Finally, the bench test has been conducted on the Diesel engine. The global operating points results show that the fuel consumption rate has decreased at most test operating points by model based calibration. The fuel consumption rate has decreased by 3.5%, and 13 mode cycle test results indicate that the proposed model based calibration method is effective and can improve the fuel efficiency by 2.72% compared with the traditional calibration

Analysis Of Diesel And Rapeseed Methyl Ester Properties In Ceup Fuel Pipeline Using Frequency Dependent Damping Model

abstract During a fuel injection cycle pressure inside Combination Electronic Unit Pump (CEUP) fuel injection system varies from low (~50 bars) to very high (~1500 bars) in fractions of seconds depending on the operating conditions. Physical properties of fuel including density, acoustic wave speed and bulk modulus also vary as a function of rapidly varying fuel pressure. A detailed analysis of these key fuel properties with our improved frequency dependent model with viscous damping developed in MATLAB is presented for both diesel and biodiesel fuel Rapeseed Methyl Ester (RME). Quantitative analysis of developed model confirms that model predictions are quite realistic and accurate across range of operating conditions of diesel engine.

Effects of fuel temperature on injection performance of an EUP system

The fuel temperature has a great influence on the characteristics of an electronic unit pump (EUP) system, especially on the injection performance. This paper studies the regularity of the high-pressure fuel supply system performance at different fuel temperatures. The injection quantity, the injection rate, the fuel pressure, and the needle lift were measured by the EUP system test bench. Investigation results showed that, with the increase of fuel temperature, the injection quantity and maximum injection rate decreased, the time of start injection was delayed, and the peak fuel pressure value decreased. For the needle valve, as the temperature was raised its closing time was advanced at low speed conditions but delayed at high speed conditions. In addition, the empirical equations for the fuel temperature effects on the circulating fuel injection quantity and peak pressure are proposed by the experimental test and simulation data. This study will help to further apply and study the engine, and provide a reference for engine fuel supply control system design.

Experimental and numerical study on the effects of the solenoid valve motion on the fuel pressure fluctuations for electronic unit pump systems of diesel engines

For electronic unit pump systems, it is an advantage for online combustion analysis and fault diagnosis to ascertain the relationship between the fuel pressure fluctuation and the movement of the solenoid valve. We experimentally and numerically investigated the fuel pressure characteristics and their connection to the transient motion of the solenoid valve. Four fuel pressure characteristic points corresponding to the start of closing time, the fully closed time, the start of opening time and the fully opened time of the solenoid valve were determined on the fuel pressure curve. A novel method was proposed to predict the solenoid valve displacement curve based on the four fuel pressure characteristic points. The validation results show that the displacement curves of the prediction and experiment are almost coincident, and the relative error of the injection quantity per cycle between the simulation and experiment is within 3 %.

Methodology to parametric design of cam profile for electronic unit pump

As to the fuel injection system of electronic unit pump, of which fuel supply principles mainly be influenced by fuel supply camshaft. Due to the requirements of the diesel engine for the fuel supply system, a new method is presented to design the constant pressure injection fuel supply cam profile. First, design principles of the fuel supply camshaft profile according to the diesel engine combustion requirement are proposed and then the parametric equation for the camshaft profile can be obtained by the proposed principles which are analyzed through math method. At last, after the prediction and comparison of the designed camshaft profile, the conclusion shows that the fuel injection system designed by the proposed principle can satisfy the injection requirements of the diesel engine. Meanwhile, the parametric equations simplify the design process of camshaft profile so as to improve the reliability and the injection performance of the fuel supply system.

Mathematical Modeling of Fuel Pressure inside High Pressure Fuel Pipeline of Combination Electronic Unit Pump Fuel Injection System

In order to completely understand the trend of pressure variations inside High Pressure (HP) fuel pipeline of Combination Electronic Unit Pump (CEUP) fuel injection system and study the impact of two major physical properties of fuel i.e., density and dynamic viscosity on pressure a 1D nonlinear dynamic mathematical model of fuel pressure inside pipeline using Wave Equation (WE) has been developed in MATLAB using finite difference method. The developed model is based on the structural parameters of CEUP fuel injection system. The impact of two major physical properties of the fuel has been studied as a function of pressure at various operating conditions of diesel engine. Nearly 13.13 bars of increase in pressure is observed by increasing the density from 700 kg/m³ to 1000 kg/m³. Whereas an increase of viscosity from 2 kg/m.s to 6 kg/m.s results in decrease of pressures up to 44.16 bars. Pressure corrections in the mathematical model have been incorporated based on variations of these two fuel properties with the pressure. The resultant pressure profiles obtained from mathematical model at various distances along the pipeline are verified by correlating them with the profiles obtained from simulated AMESim numerical model of CEUP. The results show that MATLAB mathematical results are quite coherent with the AMESim simulated results and validate that the model is an effective tool for predicting pressure inside HP pipelines. The application of the this mathematical model with minute changes can therefore be extended to pressure modeling inside HP rail of Common Rail (CR) fuel injection system.

Optimising the cam profile of an electronic unit pump for a heavy-duty diesel engine

For a fuel system with a tangent cam or a constant-velocity cam, the peak injection pressure continues to rise as the injection duration increases, but overly high peak pressures induce mechanical loads and wear, limiting the maximum engine speed and injection quantity. To improve the performance of an EUP (Electronic Unit Pump) fuel system for heavy-duty diesel engines, this work proposes a new pump cam, namely the constant-pressure cam. It helps the EUP run at a higher speed and deliver larger fuel quantities while maintaining a constant peak injection pressure, which improves the power of the heavy-duty diesel engine. A model based on the EUP was built to determine the three constraints for optimising the constant-pressure cam: 1) the pump pressure should equal the nozzle pressure; 2) the cam speed should decrease with the increase in the injection duration; and 3) the cam acceleration gradient should be zero. An EUP system was tested with the tangent cam and the optimised cam under different conditions. The experimental results show that the EUP system with the optimised cam delivers more injection quantity and runs at higher engine speeds while maintaining the same peak pressure as the tangent cam.

The Theoretical Analysis and Optimization of the Fuel Injection Drive Circuit for Diesel Engine

In order to achieve different response indifferent moment of fuel Injection Solenoid, a driving mode of Peak&Hold is generally applied to electronic control fuel injection system of the diesel engine. The theoretical analysis of high speed response and duplicate supply drive circuit based on the energy recovery is made, and a theoretical guidance for optimization design is presented. According to an electronic unit pump developed by ourselves, the optimization design of drive circuit for the fuel injection system is done. The results showed that during the process of injection, the time of current of solenoid valve form 0 to 20A is 224, and the turn-off time is 120which is a little longer than that of the high speed circuit based on the avalanche. And the turn-off time is met the requirement of control precision. With many advantages, such as energy saving and heat reducing, the high speed response and duplicate supply drive circuit based on the energy recovery will become a good choice in electronic control fuel injection system.

Key influence factors of small cycle fuel injection quantity for an electronic unit pump system of diesel engines

An electronic unit pump (EUP) is a fuel injection system which can satisfy the requirement of diesel engine's power performance and emission characteristics. In order to investigate the fluctuation in small cycle fuel injection quantity of the diesel engine at low loads, a numerical model of the EUP system was built in the AMESim environment and its accuracy was verified by experiment. The quantitative relationship between the fluctuation in minorcycle fuel injection quantity and every key parameter was studied in different cam speeds. The quantitative percentage index of the different parameters is obtained. At the same time, combining the central composite design experimental method, and taking into account the interaction of different characteristic factors, the correlation coefficients of different factors and minor cycle fuel injection quantity are revealed after the correlation analysis.

Power-on Downshift Control for Clutch-to-clutch Automatic Transmission

Power-on downshift is an effective way for the vehicle to achieve rapid acceleration and overtake. To achieve smooth power-on downshift, not only the clutch hydraulic pressure should be accurately controlled, but also the engine torque should be properly controlled. Based on the DEUTZ BF4 M 1013 turbo-charged electronic unit pump diesel engine and the Allison S2000 clutch-to-clutch automatic transmission, an integrated powertrain control strategy for the power-on downshift process is proposed. First of all, the dynamics model of the downshift process is derived using the Lagrange method. Then the method for controlling the oncoming clutch and the offgoing clutch is obtained, and the coordinated engine control based on the turbine speed is proposed. The experimental study is carried out on the test bench. The experimental results show that the shift time is less than 1 s, and the shift jerk of the power-on downshift process is smaller than 10 m/s3. The proposed integrated powertrain control strategy for the power-on downshift process can be used for the practical engineering application.

Study of Effect of Diesel Fuel Properties on Pressure Wave Profile

High pressure (HP) fuel pipeline is one of the vital components of Combination Electronic Unit Pump (CEUP) fuel injection system besides pump and injector. Effect of four key fuel properties including density, viscosity, acoustic wave speed and bulk modulus on pressure wave profile has been investigated using a 1D viscous damped mathematical model. Wave equation (WE) based mathematical model has been developed in MATLAB using finite difference method. Dynamic variations of these fuel properties during fuel injection cycles have also been incorporated in mathematical model by utilizing empirical formulas. The results show that these four key fuel properties not only vary with the pressure during fuel injection process but also define the trend of pressure wave propagation inside HP fuel pipeline.

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

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 diameter of high pressure fuel pipe and nozzle flow rate on injection characteristic parameters, were analyzed by using the developed numerical model. On the basis, a correlation analysis between the influencing factors and injection characteristics was performed by using the design of experiments (DoE) method, and the influences of these factors were quantized accordingly. Relevant results show that both the single influencing factor and the interaction among these factors correlates with the injection characteristics, and the correlation represents a complex law with the cam rotational speed. The effect of plunger diameter on the injection pressure, cycle fuel injection quantity and 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 of 500 r/min and 800 r/min, and the correlation coefficient is negative. Overall, the independent influence of the factors is more significant than the combined influence of various factors. The CEUP fuel injection system is a complicated multi-input multi-output (MIMO) nonlinear system in fact.

Analysis of Pressure Wave Model Predictions Considering Diesel Fuel Properties

Diesel fuel pressure wave inside Combination Electronic Unit Pump (CEUP) pipeline has been investigated using a 1D viscous damped mathematical model considering the effect of four key fuel properties including density, viscosity, acoustic wave speed and bulk modulus. Wave equation (WE) based mathematical model has been developed in MATLAB using finite difference method. Mathematical model results at various operating conditions of diesel engine have been verified by comparing with those of AMESim numerical model of CEUP and quantified through Root Mean Square Errors (RMSE) and Index of Agreements (IA). Dynamic variations of these fuel properties during fuel injection cycles have also been incorporated in mathematical model by utilizing empirical formulas. Predicted results show that simulated results which consider fuel properties dynamic variations as a function of pressure are more coherent to AMESim numerical model results.