Fuel Rail Pressure Research Articles

A Vibration Analysis for the Evaluation of Fuel Rail Pressure and Mass Air Flow Sensors on a Diesel Engine: Strategies for Predictive Maintenance.

This research focuses on the analysis of vibration of a compression ignition engine (CIE), specifically examining potential failures in the Fuel Rail Pressure (FRP) and Mass Air Flow (MAF) sensors, which are critical to combustion control. In line with current trends in mechanical system condition monitoring, we are incorporating information from these sensors to monitor engine health. This research proposes a method to validate the correct functioning of these sensors by analysing vibration signals from the engine. The effectiveness of the proposal is confirmed using real data from a Common Rail Direct Injection (CRDi) engine. Simulations using a GT 508 pressure simulator mimic FRP sensor failures and an adjustable potentiometer manipulates the MAF sensor signal. Vibration data from the engine are processed in MATLAB using frequency domain techniques to investigate the vibration response. The results show that the proposal provides a basis for an efficient predictive maintenance strategy for the MEC engine. The early detection of FRP and MAF sensor problems through a vibration analysis improves engine performance and reliability, minimizing downtime and repair costs. This research contributes to the advancement of monitoring and diagnostic techniques in mechanical engines, thereby improving their efficiency and durability.

GPIO-based nonsingular terminal sliding mode control for high-pressure common rail systems

The ideal fuel rail pressure is a significant component to keep the high-pressure common rail (HPCR) system work stably. The influence of time-varying fuel injection disturbance of the HPCR system is neither fully considered nor well dealt with in traditional rail pressure control approaches. To this end, the rail pressure tracking problem of an HPCR system is investigated in this paper using a generalized proportional integral observer (GPIO)-based composite control algorithm. A nonlinear model of the HPCR system is first established based on fluid dynamics and mechanics laws. Then, a GPIO is utilized to observe the time-varying fuel injection disturbance. Based on the design of a nonlinear sliding surface using the disturbance estimation, a GPIO-based nonsingular terminal sliding mode control (NTSMC) method is proposed to achieve a better rail pressure tracking control performance and a stronger robustness. Finally, a group of simulations in the MATLAB/Simulink environment and experiments in a more realistic Advanced Modeling Environment for performing Simulation of engineering systems (AMESim) environment are conducted, the results of which demonstrate the advantage and effectiveness of the proposed method.

Feasibility evaluation and optimization of liquefied petroleum direct injection (LPDI) conversion engine for low pollutant emission vehicles

Owing to environmental regulations and energy issues, the development of low-emission and high-efficiency vehicles is required. Liquefied petroleum gas (LPG) is a representative low-pollutant fuel and the third most commonly used fuel for internal combustion engines worldwide. In this study, we propose to convert the existing gasoline direct injection (GDI) to liquefied petroleum direct injection (LPDI) as the simplest way to reduce pollutant emissions from the exhaust gases of internal combustion engine vehicle (ICEV). The conventional GDI engine fuel system was converted to an LPG system, and the pollutant emissions and three-way catalyst conversion efficiency were analyzed. As a result of fuel conversion, a phenomenon occurred in which the three-way catalyst did not operate normally under some operating conditions. By calibrating the fuel pressure signal by signal converter to increase the pressure in the high pressure fuel rail, the three-way catalyst was normalized. Finally, by adjusting the fuel rail pressure of the LPDI conversion engine, the optimization was performed, and the engine performance was evaluated.

Prediction of the NOx and CO2 emissions from an experimental dual fuel engine using optimized random forest combined with feature engineering

This study was conducted to investigate the performance of a novel Random Forest (RF) model for predicting variables from an original experimental dataset of a diesel engine adapted to work with both compressed natural gas and diesel fuels. The aim was to develop a reliable framework for diesel engine emissions prediction that could assist designers, engineers, and decision-makers in optimizing engine performance and reducing emissions. The engine was modified to run on compressed natural gas as well as diesel fuel, and five variables were studied. Trials were done on a six-cylinder diesel engine to assess the RF model, employing various factors for improving engine performance and emissions, such as fuel injection angles, air-fuel ratio mixtures, diesel-to-gas exchange rates, and fuel rail pressure. A tree structured Parzen estimator and six feature engineering approaches were used to tune the RF model's parameters. In addition, the Shapley Additive explanation (SHAP) approach adapting a concept coming from game theory is employed to interpret the RF model outputs. The results analysis showed that the RF model correctly predicted the output signals of the diesel engine, with determination coefficient R2 of 0.9811, 0.9276, 0.9516, 0.8842, and 0.8944, respectively, for the studied five output variables. The RF regression model's predictive power can be used to generate an efficient modeling framework, and successfully predicts the output signals of the diesel engine, confirming the viability, effectiveness, and competitive performance.

Development of Data-Driven Models for the Prediction of Fuel Effects on Diesel Engine Performance and Emissions

<div>A modelling tool has been developed for the prediction of fuel effects on the performance and exhaust emissions of a heavy-duty diesel engine. Recurrent neural network models with duty-cycle, engine control, and fuel property parameters as inputs were trained with transient test data from a 15-liter heavy-duty diesel engine equipped with a common-rail fuel injection system and a variable geometry turbocharger.</div> <div>The test fuels were formulated by blending market diesel fuels, refinery components, and biodiesel to provide variations in preselected fuel properties, namely, hydrogen-to-carbon (H/C) ratio, oxygen-to-carbon (O/C) ratio, derived cetane number (CN), viscosity, and mid- and end-point distillation parameters. Care was taken to ensure that the correlation between these fuel properties in the test fuel matrix was minimized to avoid confounding model input variables.</div> <div>The test engine was exercised over a wide variety of transient test cycles during which fuel rail pressure, injection timing, airflow, and recirculated exhaust gas flow were systematically varied. The resulting models could predict the transient engine torque and fuel consumption, and nitrogen oxide (NOx), soot, carbon monoxide (CO), total hydrocarbon (THC), and carbon dioxide (CO<sub>2</sub>) exhaust emissions with good accuracy, indicating that the limited number of fuel property parameters selected as model inputs was sufficient to capture the fuel-related effects.</div> <div>The modelling tool can also be used to estimate the relative contributions from changes in the individual fuel inputs to changes in exhaust emissions, and this is illustrated by means of an example blending study with crude-derived diesel fuel, biodiesel, and paraffinic gas-to-liquid (GTL) diesel fuel. This type of novel numerical analysis provides insights into fuel effects which are very difficult to achieve experimentally due to the high degree of intercorrelation between fuel properties that is usually present.</div>

Optical measurements of two cylindrical and conical heavy-duty diesel injector nozzels – A comparison of reference diesel, HVO, and RME fuels

In the present work, a constant volume/constant pressure combustion chamber was utilized to measure the major parameters of vapour/liquid phases and combustion of fuel spray introduced by two heavy-duty, large-diameter diesel injectors. A conical nozzle (K factor 4) with a 300 µm outlet diameter and a 1300 µm length and a cylindrical nozzle (K factor 0) with a 300 µm outlet diameter and a 650 µm length display notably distinct impacts on the formation of the mixture, the air entrainment process, and the combustion behaviour. Several parameters, including jet and liquid spray penetration lengths, jet cone angle, and jet projected area are combined to describe spray characteristics in an inert background gas, and ignition incidence, flame lift-off length, and soot appearance time parameters are calculated to explain the combustion trend of the nozzles in a reactive gas background. These observations were conducted using four distinct optical techniques, two of Schlieren and Mie-Scattering for inert condition, and two of OH* Chemiluminescence and Natural Flame Luminosity for reactive condition. This study collects a wide variety of boundary conditions, comprising ambient pressure/temperature and fuel rail pressure, with diverse fuels, including reference diesel, HVO, and RME fuels.The findings are categorized by the jet and liquid spray behaviours in the first part, demonstrating that the jet cone angle is an injector geometry-based parameter and that the cylindrical nozzle has a larger cone angle and a shorter liquid spray length. Three distinct scenarios of the computed air-to-fuel mass ratio at the same axial positions, time steps, and injected fuel mass indicate a marginally higher air entrainment in the cylindrical nozzle and, presumably, a faster and better mixture formation. The thorough examination of the combustion characteristics indicates that a quicker formation of the initial stoichiometric region in the cylindrical nozzle results in a shorter ignition delay at most experimental locations, which ultimately results in a faster soot initiation. However, depending on the flame lift-off length and the boundary conditions, the interval between ignition and the development of soot varies considerably. Finally, it is demonstrated that, with the exception of fuel pressure variation, the flame lift-off length, which is crucial in providing the initial mixture formation prior to combustion occurrence, follows the ignition delay trend and exhibits a shorter length with a shorter ignition delay.

Research and Optimization on the Factors Influencing the Emission and Speed Jitter of GDI Engine Catalytic Converter Heating Conditions

The case study shows the process of emission and engine speed oscillation optimization of the Borgward project with engine G01, GDI, transmission 6AT, and EU5 standards. A series of methods were adopted during the optimization process, including catalyst-heating idle speed, fuel rail pressure, ignition angle, exhaust VVT position, angle injection beginning 1st of suction stroke injection in the HSP during catalyst heating (SOI), end angle of 1st injection in hp2 while catalyst heating (EOI), split factor HP2 injection compression stroke during catalyst heating, the maximum time for active catalyst heating, etc. Finally, the emission result reaches the target, and the engine speed oscillation is optimized.

A parametric study to improve first firing cycle emissions of a gasoline direct injection engine during cold start

A parametric study was carried out for the first firing cycle of a 4-cylinder, 2.0-liter, turbocharged gasoline direct injection (GDI) engine. The primary goal was to see how changes in the fuel injection parameters would affect the GDI engine combustion and emissions for the first four combustion events that constitute the first firing cycle. Experimental studies were carried out with a custom-designed powertrain control system to measure the HC emissions and pressure development for the first firing cycle. The quantitative experimental results were accompanied by simulations of the detailed temporal and spatial fuel concentration profiles using Converge CFD engine simulation software. An alternative calculation method was used to calculate the average combustion equivalence ratio for each of the four cylinders. This method showed that the majority of the cold start HC emissions during the first firing cycle was unburned gasoline and its possible decomposition products, which did not contribute significantly to the combustion and heat release. For the same amount of fuel injected into a cylinder, increased fuel rail pressure resulted in better evaporation and combustion, while slightly increasing the HC emissions during the cold start process. A multiple injection strategy was studied that split the fuel delivery between the intake stroke and the compression stroke with either one or two injections in each of those strokes (two or four injections total). The quadruple injection strategy led to better first cycle combustion, with higher engine IMEP and lower HC emissions. This resulted from a richer fuel mixture in the region near the spark plug due to better fuel evaporation and a better spatial fuel distribution. While increasing fuel rail pressure with either injection strategy failed to significantly lower the HC emissions given the same amount of injected fuel mass, higher rail pressure with the quadruple injection strategy resulted in higher IMEP for the same amount of injected fuel; this may provide the possibility to reduce the total fuel injection mass which may have benefits for both fuel consumption and emissions.

A Simulation Study on the Transient Behavior of a Gasoline Direct Injection Engine under Cold Start Conditions

<div class="section abstract"><div class="htmlview paragraph">The cold start process is critical to control the emissions in a gasoline direct injection (GDI) engine. However, the optimization is very challenging due to the transient behavior of the engine cold start. A series of engine simulations using CONVERGE CFD™ were carried out to show the detailed process in the very first firing event of a cold start. The engine operating parameters used in the simulations, such as the transient engine speed and the fuel rail pressure (FRP), came from companion experiments. The cylinder pressure traces from the simulations were compared with experiments to help validate the simulation model. The effects of variation of the transient parameters on in-cylinder mixture distribution and combustion are presented, including the effects of the rapidly changing engine speed, the slowly vaporized fuel due to the cold walls, and the low FRP during the first firing cycle of a 4-cylinder engine. Comparison was also made with non-transient steady state operation. It was shown that the injection-induced tumble ratio in the cylinder varied for different engine speed cases, resulting in a better fuel distribution in the low engine speed case. A relatively high turbulence level during the combustion process was seen in the transient engine speed case that led to strengthened combustion. The fuel tracking from the simulation indicated that about 30% of the fuel remained unreacted at a very late crank angle, in which 8% was in the gas phase and 22% in the liquid phase as wall films. As the FRP increased, the fuel droplets became smaller, and more fuel vaporized before hitting the piston. But the splash and rebound fuel fraction off the piston bowl was even less, resulting in a lower overall gas-phase equivalence ratio in the first firing event for the high FRP case. On the other hand, the fuel distribution was more homogeneous under the high FRP condition due to the high injection velocities. There should be an optimal FRP value, but it was difficult to discern since the peak pressures in different FRP cases were similar and turbulence levels varied in a non-monotonic way, as well, which would lead to cycle-to-cycle variations in the real engine.</div></div>

Fuel Rail Pressure Control Characteristics of a GDI High-Pressure Fuel Pump Using a Newly Developed Experimental System Controlled with a Microcontroller

An experimental system was developed to evaluate the fuel injection parts of a gasoline direct injection engine. An AC motor and an inverter were used to rotate the camshaft in the engine cylinder head. A single plunger high-pressure fuel pump (HPFP) driven by a square cam at the end of the camshaft was used in the gasoline direct injection engine. The rotation position of the square cam was measured by a rotary encoder. The developed system allows control of the camshaft rotation speed, the HPFP pressure control valve (PCV) opening and closing timing, and the fuel injection duration, which are three important factors affecting the fuel rail pressure (FRP). It is confirmed that the fuel rail pressure can be made to vary wit different combinations of these three factors. By using the experimental system developed in this study, the fuel rail pressure can be effectively controlled in the range of 3 MPa to 20 MPa. The most influential factor for control of the fuel rail pressure was the HPFP PCV opening and closing timings. With the proposed using the experimental system, the rail pressure, fuel rail pressure wave characteristics, and the injector drive characteristics can all be assessed under various fuel injection conditions.

Mechanisms of fuel injector tip wetting and tip drying based on experimental measurements of engine-out particulate emissions from gasoline direct-injection engines

Gasoline fuel deposited on the fuel injector tip has been identified as a significant source of particulate emissions at some operating conditions of gasoline direct-injection engines. This work proposes simplified conceptual understanding for mechanisms controlling injector tip wetting and tip drying in gasoline direct-injection engines. The objective of the work was to identify which physical mechanisms of tip wetting and drying were most important for the operating conditions and hardware considered and to relate the mechanisms to measurements of particulate number emissions. Trends for each of the physical processes were evaluated as a function of engine operating conditions such as engine speed, start of injection timing, engine load, fuel rail pressure, and coolant temperature. The effects of fuel injector geometries on the tip wetting and drying mechanisms were also considered. Several mechanisms of injector tip wetting were represented with the conceptual understanding including wide plume wetting, vortex droplet wetting, fuel dribble wetting, and fuel condensation wetting. The main tip drying mechanism considered was single-phase evaporation. Using the conceptual understanding for tip wetting and drying mechanisms that were created in this work, the effects of engine operating conditions and fuel injector geometries on the mechanisms were compared with experimental results for particulate number. The results indicate that measured particulate number was increased by increasing injected fuel mass. Increasing injected fuel mass was suspected to increase tip wetting via wide plume wetting and vortex droplet wetting mechanisms. Particulate number was also observed to increase with hole length. Longer hole length was suspected to result in higher tip wetting via vortex droplet and fuel dribble wetting mechanisms. Longer timescale was found to decrease particulate number emissions. Lower speeds and early injection timings increased the timescale. Similarly, higher coolant temperature decreased particulate number. The coolant temperature influenced tip temperature resulting in higher tip drying.

Online ANN-based fault diagnosis implementation using an FPGA: Application in the EFI system of a vehicle

In this research, fault detection and diagnosis (FDD) scheme for isolating the damaged injector of an internal combustion engine is formulated and experimentally applied. The FDD scheme is based on a temporal analysis (statistical methods), as well as in a frequency analysis (fast Fourier transform) of the fuel rail pressure. The arrangement of the scheme consists of three coupled artificial neural networks (ANNs) to classify the faulty injector correctly. The ANNs were trained considering five different scenarios, one scenario without fault in the injection system, and the other four scenarios represent a fault per injector (1 to 4). The Levenberg–Marquardt (LM), BFGS quasi-Newton, gradient descent (GD), and extreme learning machine (ELM) algorithms were tested to select the best training algorithm to classify the faults. Experimental results obtained from the implementation in a VW four-cylinder CBU 2.5L vehicle in idle operating conditions (800 rpm) show the effectiveness of the proposed FDD scheme.

A multispectral, extinction-based diagnostic for drop sizing in optically dense diesel sprays

Diesel sprays present a challenging environment for detailed quantitative measurement of the liquid field, and to date, there have been only a few efforts to characterize drop sizes within the family of Engine Combustion Network (ECN) diesel sprays. Drop sizing diagnostics, including optical microscopy and Ultra-Small Angle X-ray Scattering (USAXS), have been recently demonstrated in Spray A/D ECN activities, but little data exist to validate these results. This work therefore seeks to extend the available ECN data on the liquid phase field and provide a new comparative data set for assessment of previous ECN drop sizing measurements. In particular, this work presents the development of a two-wavelength, line-of-sight extinction measurement to examine liquid volume fraction and the corresponding droplet field in high-pressure fuel sprays. Here, extinction of lasers emitting at 10.6 μm and 0.633 μm are used for the measurement. To enable quantification of the liquid field in optically dense regions of the spray, a transfer function is developed to account for the influence of multiple scattering. The developed diagnostic is then applied to n-dodecane sprays from the ECN Spray A and Spray D injectors at varying fuel rail pressures and atmospheric chamber condition. Overall, the results show a reasonable agreement with droplet sizes measured using USAXS, as well as from more recent measurements using a Scattering-Absorption Measurement Ratio (SAMR) technique also developed in our group. This is particularly the case near the spray periphery, where on average, less than 40% difference in the measured Sauter mean diameter is observed. Nonetheless, an apparent discrepancy is observed between drop sizes from different diagnostics close to the jet centerline (i.e. nearly 100% difference between available data for Spray D injector). Moreover, the presented diagnostic shows an improved capability in the dilute regions of the spray, where x-ray-based diagnostics are generally subject to high noise and low signal sensitivity.

Terminal sliding mode control of rail pressure for gasoline direct injection engines

The desired fuel rail pressure is a crucial factor for guaranteeing the gasoline direct injection (GDI) engine to work stably. In order to solve the rail pressure control problem, the detailed nonlinear model of GDI is derived and reasonable simplification of this model is carried out for the following controller design. Terminal sliding mode control strategy is proposed to design the rail pressure controller with Lyapunov stability. The designed approach with the fast terminal sliding mode surface makes the system have the capacity of global fast convergence and achieves precise tracking control. To demonstrate the validity of the designed control method, simulations are conducted by tracking the different reference rail pressures. Results show that the designed controller tracks the given reference accurately and has strong robustness.

Development and Demonstration of Control Strategies for a Common Rail Direct Injection Armoured Fighting Vehicle Engine

<p class="Abstract">The development of a controller which can be used for engines used in armoured fighting vehicles is discussed. This involved choosing a state of the art reference common rail automotive Diesel engine and setting-up of a transient engine testing facility. The dynamometer through special real-time software was controlled to vary the engine speed and throttle position. The reference engine was first tested with its stock ECU and its bounds of operation were identified. Several software modules were developed in-house in stages and evaluated on special test benches before being integrated and tested on the reference engine. Complete engine control software was thus developed in Simulink and flashed on to an open engine controller which was then interfaced with the engine. The developed control software includes strategies for closed loop control of fuel rail pressure, boost pressure, idle speed, coolant temperature based engine de-rating, control of fuel injection timing, duration and number of injections per cycle based on engine speed and driver input. The developed control algorithms also facilitated online calibration of engine maps and manual over-ride and control of engine parameters whenever required. The software was further tuned under transient conditions on the actual engine for close control of various parameters including rail pressure, idling speed and boost pressure. Finally, the developed control strategies were successfully demonstrated and validated on the reference engine being loaded on customised transient cycles on the transient engine testing facility with inputs based on military driving conditions. The developed controller can be scaled up for armoured fighting vehicle engines.</p>

Experimental Investigations of the Effects of Electric Control Impulse on Injection Characteristics of Common Rail Type Injector

Background/Objectives: The motor-less fuel stand has been described capturing high-speed video in the process of fuel jet development in Common Rail type injector. Methods: The experiments were carried out simultaneously recording the electric signals of the start and end moments of the electrical impulse controlling the injector with digital color oscilloscope Tektronix TDS-2014С and high-speed imaging of the fuel jet sprays with color video camera FASTCAM SA-X2. Findings: The delays of the start and termination of actual fuel injection that depend on the electrical impulse for the injector control have been determined and the dynamics of the fuel jet development has been observed under the fuel rail pressure from 100 to 165 MPa. The dependency of the duration of the fuel injection process on the duration of the electrical impulse controlling the injector has been established. Applications/Improvements: The results of the study can be used for diesel engine design and commissioning and for improving the shape of the combustion chamber to ensure better carburetion in the cylinder.

솔레노이드 타입 디젤 커먼레일 인젝터 구동을 위한 전류 파형 변화에 따른 분사 연료 압력파 특성

Injected fuel pressure waves of a common rail injector with various current profiles supplied to the injecor were measured using Bosch method. In order to drive the common rail injector, the current in the solenoid should be controlled using what is known as a peak and hold pattern, which consists of a high current level with a short time duration (peak) in the first step and a low current level with a long time duration (hold) in the subsequent step. The current profile can be shaped by swithcing an injector driving power source with the peak and hold waves. The capture, compare and PWM (CCP) pin in the microprocessor was used to generate the combined peak and hold waves. The PWM square wave generated from the CCP pin has a duty ratio of 100% for the peak current and 10% or 30% for the hold pattern. Five patterns of the current profile were generated by combining the peak and hold wave. The common rail pressure is controlled at 75, 100, and 130 MPa. As the fuel rail pressure increases, the variations of the measured fuel injection pressure wave according to the current profiles decrease.

Influence of MFB50 control on emission dispersions according to engine parameter changes for passenger diesel engines

Combustion phase variations in diesel engines due to production tolerance, engine aging, and different combustion conditions cause performance deterioration of fuel economy, torque, and emissions. Therefore, the combustion phase should be controlled by feedback information. A well-known method to control the combustion phase is mass fraction burnt 50% (MFB50) control using in-cylinder pressure. MFB50 control can retain performance through combustion phase compensation despite production tolerance, engine aging, and different combustion conditions. However, MFB50 can compensate only for variations caused by combustion phase changes; therefore, further study is required to supplement the limitation of MFB50 control. In this study, to analyze the effect of MFB50 control on combustion, MFB50 is controlled by adjusting the main injection timing using in-cylinder pressure at 1500 rpm and a BMEP of four bar according to engine parameter changes. The parameters are fuel rail pressure, boost pressure, mass air flow, swirl valve open, main injection quantity, pilot injection timing, and quantity. While the engine parameters were changing, the influence of MFB50 control on the combustion and emissions was analyzed to establish improvement points for combustion feedback control. Our experiments demonstrated that MFB50 control reduced NOx dispersions but at the cost of increasing PM dispersions. Therefore, to improve MFB50 control, a control algorithm that can handle PM emission dispersion needs to be considered.

A control-oriented NOx emissions model for diesel engines

A control-oriented, low computational cost nitrogen oxides emissions model for a diesel engine is presented. The model is based on zero-dimensional one-zone nitric oxide formation thermodynamics. The main inputs to the model are measured cylinder pressure, engine speed and manifold air flow rate. As only three model parameters are required, the calibration effort is minor. Instead of solving nonlinear equations to obtain the oxygen concentration from dissociation reactions, a simple estimation method used the estimated number of moles in the burned zone. The model was validated using engine data and show that the model can predict emissions with high accuracy as they vary with load, start of injection, fuel rail pressure and exhaust gas recirculation rate. As there are few, relatively simple algorithms involved, this model can easily be implemented online. It also has potential to be used in the control of both exhaust after-treatment and the engine combustion process.

Flatness-based Feedforward and Feedback Control for Fuel Rail System of Gasoline Direct Injection Engine

For gasoline direct injection (GDI) engines, obtaining desired rail pressure has become a key prerequisite of fuel injection quantity precise control. Since improved control performance and robustness will translate into better combustion stability, fuel economy and emissions. This paper develops a feedforward-feedback controller based on a nonlinear model of fuel rail system, where nominal feedforward control is derived by differential flatness and fuel rail pressure is selected as flat output. In feedback part, to simplify the design, the system is linearized on equilibrium point using Taylor series expansion, and Lyapunov method is used to ensure stability of closed-loop error system. Finally, the proposed controller is verified by fuel rail system simulation model established in AMESim software package, the simulation results in different pressure references demonstrate the effectiveness of the control system.