Establishment of a Real-Time Simulation of a Marine High-Pressure Common Rail System

In this paper, the high-pressure common rail system of the marine diesel engine is taken as case study to establish a real-time simulation model of the high-pressure common rail system that can be used as the controlled object of the control system. On the premise of ensuring accuracy, the real-time simulation should also respond quickly to instructions issued by the control system. The development of the real-time simulation is based on the modular modeling method, and the high-pressure common rail system is divided into submodels, including the high-pressure oil pump, common rail tube, injector, and mass conversion. The submodels are built using the “surrogate model” method, which is mainly composed of MAP data and empirical formulas. The data used to establish the real-time simulation are not only from the empirical research into the high-pressure common rail system, but also from simulations of the high-pressure common rail system undertaken in AEMSim. The data obtained from this real-time simulation were compared with the experimental data to verify the model. The error in fuel injection quality is less than 5%, under different pressures and injection durations. In order to carry out dynamic verification, the PID control strategy, the model-based control strategy, and the established real-time simulation are all closed-loop tested. The results show that the developed real-time simulation can simulate the rail pressure wave caused by cyclic injection according to the control signal, and can feedback the control effect of different control strategies. Through verification, it is clear that the real-time simulation of the high-pressure common rail system can depict the rail pressure fluctuation caused by each cycle of fuel injection, while ensuring the accuracy and responsiveness of the simulation, which provides the ideal conditions for the study of a rail pressure control strategy.

Investigation of fuel injection rate identification algorithm based on rail pressure fluctuation characteristics induced by injection

As an important part of the common-rail (CR) fuel system for diesel engines, the injector circulation capacity and the fuel injection mass flow rate vary with carbon deposition and wear, affecting the engine output performance. This study proposes a method to identify the fuel injection rate online, based on the rail pressure fluctuation characteristics induced by fuel injection. The control algorithm uses the signal from the existing rail pressure sensor; the diesel engine does not require modification or additional sensors. A quasi-dimensional model of the CR fuel system was built to analyse the rail pressure wave fluctuation characteristics, and a parameter K was defined as the pressure drop rate. Based on K, a control algorithm was proposed. A high-pressure fuel pump test rig was built to test the fuel injection performance under different operating conditions, and the experimental data were processed by wavelet transform. From the test data, the K of the CR system was analysed using the feedback of the rail pressure sensor. The experimental results show that the value of K increases with an increase in the initial pressure and injection pulse, and is independent of the injection mode. The algorithm is feasible, and works more accurately with a longer injection pulse and a lower pump speed. This method uses the existing rail pressure sensor, does not incur extra cost and has great potential for improving the injection accuracy.

Injection control strategy of diesel engine based on speed segment PID and operating parameter adaptation

Aiming at the problems of low precision, poor anti-interference and poor follow-up in the control parameters for the diesel engine fuel injection system, this paper studies the control method of the high-pressure common rail electronic control fuel injection system of the diesel engine, constructs the high-pressure common rail fuel injection control system based on the ECU, and establishes the speed segment PID control model of fuel injection quantity, common rail pressure, fuel injection timing and fuel injection rate by using MATLAB/Simulink. The fuel injection quantity and timing are simulated. In order to realize all-round and flexible control of the diesel engine under different working conditions, and to achieve the desired optimal performance in all aspects, the optimization control method of the injection law for the diesel engine is studied. The diesel engine fuel injection control strategy based on speed segment PID and operating parameter adaptation is proposed to realize precise control of the common rail pressure, injection quantity, injection timing and injection rate under different working conditions. The simulation calculation and bench test show that the maximum fluctuation of rail pressure at idle speed is only 5 MPa, and the time to reach stability is only 1.25 s, which greatly improves the control accuracy, anti-interference and follow-up ability of the injection parameters.

Fuel Economy Results From Diesel Engine Tuning for Steady Speed and Drive Cycle Operation

As part of efforts to mitigate climate change by reducing fuel consumption in the transport sector in the Philippines, this paper presents the initial results of an investigation on the effects of engine tuning on fuel economy for different drive cycles using a commercially available piggyback tuning “chip” to modify fuel rail pressure from stock settings of a CRDI diesel passenger van. The drive cycles used in this study were the Japanese 10-15 Mode, US highway fuel economy test (HWFET), and one labeled “SMN” based on a Metro Manila local route. An initial steady state vehicle fuel economy performance map at five speeds per gear position and stock tuning was obtained from chassis dynamometer tests. The same series of tests were done with the tuning chip’s settings of progressively lower rail pressure to identify the setting giving lowest fuel consumption at each gear. Fuel consumption reduction of up to 47% was observed although not all speeds at a given gear and tuning setting gave reduced values. These lowest fuel settings were applied to corresponding gear positions in each of the selected drive cycles resulting to “specific tuning maps” per drive cycle. The test vehicle was then driven with these drive cycle-specific tuning maps and the fuel economy measured. It was found that overall fuel economy decreased with drive cycle-specific tuning settings. It was then decided to try using a constant tuning setting throughout a drive cycle to see if fuel economy improved. Trials with the Japanese 10-15 Mode cycle at different constant lower rail pressure settings likewise gave overall lower fuel economy. However, a more detailed look showed that in the constant-speed portions of the cycle, fuel consumption savings of up to 35% were realized while it worsened in the accelerating and decelerating sections. The drive cycle test results indicate that the engine ECU compensated for the lowered rail pressure, maybe with increased injection duration, to increase the amount of fuel injected to meet the road-load requirements imposed by the drive cycle. Control response instabilities may have also contributed to higher fuel consumption. Engine tuning by rail pressure reduction only was most effective in reducing fuel consumption for steady state driving and ineffective for transient driving under the conditions and methodology of this study.

Hydraulic Interactions between Injection Events Using Multiple Injection Strategies and a Solenoid Diesel Injector

An experimental study was performed to explore the influence of dwell time on the hydraulic interactions between injection events using pilot injection strategy, split injection strategy, post injection strategy and a solenoid diesel injector. To do so, a sweep of dwell time from 0.55 up to 2 ms using all multiple injection strategies and levels of rail pressure, of 80, 100 and 120 MPa, and single level of back pressure, of 5 MPa, was performed. The hydraulic interactions between injection events were characterized through the second injection hydraulic delay and second injection mass in an injection discharge curve indicator equipped with all the components required for its operation and control. In order to define the operating conditions of the multiple injection strategies, to ensure the same injected fuel mass in all cases, the characteristic curves of injection rate for the solenoid diesel injector studied were obtained. The second injection hydraulic delay increases with dwell time values in the range of 0.55–0.9 ms for all multiple injection strategies and levels of rail pressure tested. Conversely, the second injection hydraulic delay decreases with dwell time values higher than 0.9 ms. Moreover, the second hydraulic delay depends mainly on the dwell time and not on the injected fuel mass during the first injection event. The second injection mass increases with dwell values less than 0.6 ms. By contrast, the second injection mass is not significantly affected by that of the first injection at a dwell time higher than 0.6 ms.

DEVELOPING AND VALIDATING A GT-SUITE BASED MODEL FOR A SECOND GENERATION COMMONRAIL SOLENOID INJECTOR

Injection profiles, containing important parameters like injection rate, directly affect the spray structure, fuel-air mixture quality, and as such the physical and chemical processes occurring in the IC engine’s combustion chamber. Therefore, injection profiles are one of the keys to improving power, thermal efficiency and minimizing the emission for IC engines. In this paper, a GT-Suite - based simulation model for a second generation solenoid commonrail injector typically utilized in Hyundai 2.5 TCI-A diesel engines, has been successfully developed and validated. The validation is done by using experimental data are acquired by a Zeuch’s method-based Injection Analyzer (UniPg STS) in University of Perugia, Italy. The calibration data is measured over a wide range of rail pressure and energizing time (ET) corresponding to the engine operating conditions. The results show that the injector model developed here is reliable and suitable for examining the injector’s hydraulic characteristics. The difference in start of injection values obtained through experiment and simulation is only about 15 µs. The total injection volumes obtained through experiment and simulation under ET > 0.8 ms is less than 10 % while the difference is quite high under ET < 0.8 ms and high rail pressure (up to 34.5 %).

Experimental Investigation of the Rail Pressure Fluctuations Correlated with Fuel Properties and Injection Settings

Injection-induced rail pressure fluctuations are proven to cause nonuniform spray development. These fluctuations are also responsible for generating lower injection pressures, to the detriment of jet penetration length and break-up timing. Despite the vast literature dealing with such issues, several aspects of rail pressure fluctuations remain unclear. Additionally, the need for compliance with the emission legislation has shed light on the potential of alternative fuels, which represent a pathway for sustainable mobility. This scenario has motivated the present study dealing with the assessment of the time history of rail pressure correlated with fuel properties. Tests have been performed using a last-generation common rail injection equipment under various injection settings, employing diesel and 2-methylfuran-diesel blend. This paper describes the research activity and aims to provide new insights into the correlation of rail pressure fluctuations with fuel properties.