Pressure Common Rail Research Articles

Evaluation of NOx and PN Emission in Relation to Actuator Control.

This study aimed to investigate the interrelationships between key harmful emission components, nitrogen oxides (NOx), and particulate numbers (PNs) in diesel engine exhaust and the control actuators of diesel engines. This research involved conducting a series of experiments under fixed parameters within an engine brake laboratory environment to elucidate these correlations. The objectives of this study were to conduct a comprehensive review of the relevant emissions technology literature and a comparative assessment of particle measurement methods based on dilution ratios and develop innovative aerosol preparation principles tailored to condensation particle measurement. Additionally, this research involved designing and implementing an aerosol preparation unit based on the newly developed principles, along with the creation of test cell control programs using the AVL PUMA Open TST editor interface and Visual Basic. Furthermore, this study was concerned with conducting evaluations of fixed-parameter engine dynamometer tests to explore the functional relationships between the emission of 10/23 nm particles, NOx emissions, common rail pressure variations, and exhaust gas recirculation levels. This study aimed to enhance the understanding of diesel engine emissions dynamics and contribute valuable insights for developing more efficient and environmentally friendly engine control strategies.

Experimental study on diesel spray flame and wall heat transfer of two-dimensional combustion chamber: effect of common rail pressure

Reducing the heat transfer occurring during the spray combustion of diesel engines remains a challenging task. This study investigated the spray flame behaviour, wall heat flux, and heat transfer phenomena of diesel engines at varying common rail pressures. A rapid compression and expansion machine (RCEM) was employed to simulate a single cycle of diesel spray combustion using split injection sprays. The two-dimensional (2D) stepped piston cavity is a uniquely shaped model used to describe the spray flame behaviour in the combustion chamber. To investigate the heat transfer phenomena, we installed wall heat flux sensors in the cylinder and cavity side. The results indicated that higher common rail pressures increased the peak value of the wall heat flux and reduced the combustion duration and the luminous flame. The higher common rail pressure led to an increase in spray velocity, thereby enhancing the turbulence level. This increase in turbulence to higher peak value of the wall heat flux. The highest peak value of the wall heat flux was reached by the cylinder head owing to the intense combustion region, followed by the cavity bottom owing to the highest flame temperature occurring around this location. Additionally, the heat transfer phenomena in diesel engines were successfully represented by local Nu-Re correlations. Our results contribute to the discussion on heat transfer phenomena that influence the thermal efficiency of diesel combustion engines.

The Research and Development of a Jet Disturbance Combustion System for Heavy-Duty Diesel Engines

Herein, a diesel engine jet disturbance combustion system was proposed to achieve efficient and clean combustion under heavy load conditions in heavy-duty diesel engines. The key components of the combustion system were designed, and a research platform was constructed. Focusing on the internal combustion conditions of the disturbance chamber and the developmental path of high-speed jets, the design and comprehensive optimization of the jet disturbance combustion system were carried out. Following optimization, the peak internal heat release rate increased from 86 J/deg to 269 J/deg, and the cumulative heat release increased by 112 J, significantly enhancing the energy of the disturbance chamber jet. Then, considering combustion optimization and the heat transfer loss from the piston, it was determined that the optimal configuration for the disturbance chamber jet channel angles was 60 deg inter-channel angle and 10 deg channel incidence angle. This configuration allowed the disturbance chamber jet to precisely disturb the concentrated mixture area in the middle and late stages of combustion. The intervention of the disturbance chamber jet provided sufficient energy for the fuel–air mixing process and complicated the gas flow state in the main combustion chamber. Despite its low-momentum density, the residual mixture in the cylinder maintained a high mixing rate after the end of the fuel injection process. Single-cylinder engine test results showed that a diesel engine using this jet disturbance system and a 180 MPa common rail pressure fuel system achieved 52.12% thermal efficiency.

On PID Controllers for a Complex-Order Fractional Model of an Automotive Injection System

Recent studies have shown that complex-order fractional operators allow for compact modeling with simpler structures and less parameters than models based on integer-order operators and even non-integer real-order operators. This work verifies the usefulness and potential of a complex-order fractional model when used to set parameters of a PID controller regulating the common-rail pressure in the injection system of a compressed natural gas engine. Parameters are derived by a general particle swarm optimization that considers a cost function weighting the performance and robustness measures. Simulation results show the effectiveness of the complex-order fractional model-based PID controller through the response to step references, the rejection of disturbances, the low sensitivity to variations of the injection system parameters.

Effect research of fuel injection and pressurization pulse width on injection characteristics of ultra high pressure common rail system

Ultra high pressure common rail system can realize adjustable injection rate by controlling the relationship between fuel injection and pressurization timing, and then affect the fuel injection characteristics of diesel engine. In order to ascertain the effect law and its formation mechanism of the fuel injection and pressurization pulse width on the fuel injection characteristics of ultra high pressure common rail system, on the basis of introducing the mathematical model of the system, the simulation model of ultra high pressure common rail system was established, and the accuracy of the model was verified by performance experiment, the effect of fuel injection and pressurization pulse width on the fuel injection characteristics of the system under different common rail pressure were analyzed. The results show that with the increase of fuel injection pulse width, the shape of fuel injection rate curve is similar to saddle shape and the proportion of large fuel injection rate range in the whole injection process increases gradually. At the same time, the fuel injection opening delay remains unchanged, but the fuel injection closing delay increases significantly when the fuel injection pulse width is small (0.6~1 ms), while it remains basically unchanged when the fuel injection pulse width is large (1~1.4 ms). With the increase of pressurization pulse width, the shape of fuel injection rate curve is similar to saddle shape and remains unchanged under the condition of small injection pulse width, while the fuel injection rate curve shape may appear similar to the "inverted saddle-shaped" under the condition of large injection pulse width, this is due to the rapid decrease of pressurization pressure caused by the closing of the solenoid valve control signal in the pressure-amplifier device before the end of fuel injection.

Compound control of rail pressure in dual common rail injection system based on a dual regulating valve

To improve the performance of fuel injection in high power diesel engines, high pressure dual common rail system (HPDCRS) is made to match high power diesel engine, proportional-integral-derivative (PID) compound control for rail pressure is proposed based on dual regulating valve: pressure balance valve (PBV) and pressure control valve (PCV), a PID hybrid neural network (PID-HNN) is provided to complete tuning and match of PID coefficient automatically, simulation control modelling of rail pressure is made by MATLAB software, pressure control comparison of dual common rail is made with PID compound control method. The pressure control effects illustrated that PID compound control of dual regulating valves can rapidly trace different target pressure and reduce rails pressure wavelet, and feasibility of compound control is verified in dual common rail pressure.

Experimental study on wall heat transfer from diesel spray flame in two-dimensional combustion chamber operated with rapid compression and expansion machine (RCEM)

Heat transfer phenomenon in internal combustion diesel engine is one of problems to be solved. This study was conducted to investigate the relationship between diesel spray impingement, combustion processes, and heat loss using a rapid compression and expansion machine (RCEM). Furthermore, spray combustion and heat transfer processes were investigated using multiple injection strategies with a 6-holes injector. The amounts of diesel fuel used in the pilot, pre-injection, and main injection sprays were 3.964, 0.747, and 11.205 mg, respectively. Variations in common rail pressure conditions (30, 120, and 180 MPa) were applied to properly investigate spray evaporation, air–fuel mixture formation, and heat transfer in the combustion chamber. In addition, a local wall heat flux sensor was installed in the cylinder (head and liner) and piston cavity (upper lip, lip, and bottom) to measure the heat flux distribution, and a diffused backlight illumination method was used to visualize the spray and flame behavior in the combustion chamber and 2D piston cavity. The results showed that the impingement flame surrounding the cylinder head contributed to the highest magnitude and longest duration of the heat flux on the cylinder side owing to the spray flame velocity, impingement, and residence time. Meanwhile, the highest different temperature at cavity bottom induced more heat flux on the cavity side than that on the squish side. In addition, the higher injection pressure increased the spray momentum and spray tip penetration which led to a better air–fuel mixture, better evaporation rate, and less flame residence that contributed to reduce the accumulated heat loss in combustion chamber. Furthermore, a low common rail pressure was found to induce a greater difference in the accumulated heat flux ratio than a high common rail pressure which is owing to longer flame residence time in the combustion chamber. They were approximately 14% and 6% greater than that compared to the baseline common rail pressure which mean that a high common rail pressure contributes for the improving thermal efficiency in spray combustion.

Influence of the flow area around the ball valve on the flow characteristics of the injector control valve

The increase in common rail pressure can lead to increased cavitation inside the injector, resulting in degradation of injector performance and reduced life. The paper investigates the effect of the pressure block structure parameters (initial flow area around the ball valve) on the velocity field, pressure field, fuel gas phase volume fraction and drain rate of the control valve. The relationship between the initial flow area around the ball valve on the cavitation strength and unloading rate inside the valve was revealed. The results show that both the reduction of the flow area around the ball valve and the increase of the cavitation intensity inhibit the rate of oil discharge from the control valve. The reduction of the fuel flow area inhibits the expansion of the low-pressure region (0–1 MPa) within the flow layer, thus limiting the development of cavitation. The reduction of the cavitation area increases the fuel flow rate, however, the increase in flow rate increases the cavitation phenomenon, and these changes form a cycle (Reviewer 5. comment 2). The increase in cavitation inhibits the control valve pressure relief rate more significantly than the decrease in the initial flow area around the ball valve. Based on this, a stepped-pressure block model is proposed. The stepped pressure block model can effectively reduce the cavitation strength near the seal and enhance the oil discharge rate of the control valve. The study can provide a reference for the engineering optimization design of high-pressure common rail injector control valves.

Study on observation method of injection pressure curve in high pressure common rail system

The performance of the diesel engine was determined by the injection pressure of the high pressure common rail system. The observation method of the injection pressure curve was of great value in evaluating the operating conditions of the diesel engine. However, the observation method could make it impossible to directly observe the injection pressure data on a high pressure common rail system in operation. In this paper, common rail pressure signals and control pulse widths, which were easy to collect, were used as the basis for proposing a GRU (Gated Recurrent Unit) based model for the observation of injection pressure curves of high pressure common rail system in order to solve the above problem. The accuracy and precision of the model was verified by the experiments and compared with commonly used simulation models. From the results, it was concluded that the overall accuracy of the injection pressure curve observation was similar to that of the simulation model, but the accuracy was higher around the peak of the injection pressure, as well as the equipment requirement was low and the calculation speed was fast. The mean EMD of the curvilinear observation model of injection pressure of high pressure common rail system is similar to that of the 1D simulation model, with 37.88 and 33.62 respectively. The overall difference in injection pressure between the two models is similar with 53.62 and 54.23 MPa respectively. On the same computing platform, the average computation time of the test set containing five states is 0.0113 s, and the simulation time of each running state is 12951.6 s using AMESim software.

Study on the pressure fluctuation characteristics of the high-pressure common rail system with a distributor

In allusion to the problem of common rail pressure fluctuation when the high-pressure common rail system (CRS) using double rails, a numerical simulation model of a V-type 8-cylinder engine CRS was established by using AMESim software, and the suppression of pressure fluctuation with and without distributor was studied. The optimum structure dimension of the distributor with length of 100 mm and inner diameter of 9 mm was obtained by uniform design method. Then the pressure surge characteristics of CRS was researched. The research results showed that the installation of the distributor cut down the amplitude of the pressure oscillation of the common rail by more than 62.28%. Therefore, the designed distributor can effectively suppress the rail pressure fluctuation and improve CRS stability.

Angle tracking control of integrated hydraulic transformer inner loop servo system

Integrated hydraulic transformer based on hydraulic common pressure rail system has significant energy saving effect. The control of the inner loop (i.e. valve-controlled hydraulic swing motor system) is closely bound up with the performance of the integrated hydraulic transformer. Considering the input delay, output constraints, and actual working conditions in the inner loop system, an extended state observer-based finite-time backstepping filter control strategy is designed to guarantee energy-saving performance. Firstly, an extended state observer is constructed to observe the state variables and acquire the estimated value of the unknown term. Secondly, the state equation of the system is transformed by the Pade approximation, and the robust controller is designed based on finite-time stability theory and backstepping algorithm to ensure the output of the system in the constraint set. Finally, the proposed control algorithm is compared with the traditional control algorithm through experiments, and the effectiveness is verified.

Nonlinear dynamic model for the free rotor of the swash plate-rotating hydraulic transformer

Hydraulic transformer (HT) is an energy conservation component used in the common pressure rail system and achieves an excellent energy-saving effect in construction machinery and vehicle transmission. This paper reports a complete nonlinear dynamic model and validation for the free rotor in a swash plate-rotating hydraulic transformer (SPRHT), accounting for various time-varying effects. A parameter characterization model for the oil properties considering gas-liquid phase and pressure is described. Based on the lumped element method, the fluid dynamic model for the working chambers is established, taking account of the variation of the control volume/flow area in the working chambers and leakage. The dynamic model for the free rotor is constructed, accounting for the piston distribution and nonlinear friction. Combining the above models, the speed of the free rotor is solved by the Runge-Kutta method. The SPRHT is simulated in the AMESim. Particularly, a prototype is developed, and the dynamic test is carried out. Then the potential of the nonlinear model for the free rotor is verified. The proposed nonlinear dynamic model of the free rotor can be used for the dynamic behavior analysis and energy efficiency optimization of the HT.

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.

Research on transmission and coupling characteristics of multi-frequency pressure fluctuation of high pressure common rail fuel system

To analyze the coupling characteristics of system-level fuel supply and injection and the mechanism of multi-frequency pressure fluctuations affecting system stability, a prediction model of the high-pressure common rail system was established. The effects of common rail pressure, control pulse width and engine speed on pressure fluctuations were analyzed. Simultaneously, the influence of different hydraulic components such as pumps, rails, and injectors on pressure fluctuations was analyzed by employing hydraulic decoupling method. The influence of pressure fluctuations caused by fuel supply characteristics of pump, filtering effect of rail and fuel injection characteristics of injector on the entire system was studied. The result demonstrates that adjusting target rail pressure and control pulse width alters the fuel supply ability and fuel injection level respectively. During the fluctuation process, the pressure fluctuation overshoot is about 7.7%, and the steady state fluctuation is about ± 1.5%. The adjustment of engine speed influences the overall trend of pressure fluctuations apparently. Additionally, the pressure fluctuations in the system are mainly induced by the coupling of high and low frequency pressure waves. Among them, low-frequency fluctuations everywhere are highly consistent, whereas high-frequency fluctuations are affected significantly by working properties of hydraulic components. Through decoupling analysis, it is illustrated that the fuel pump fluctuations affect the entire fluctuation trend to a great extent. The volume of common rail pipe has an effect on the fluctuation degree and filtering capability. The transient motions of fuel inlet valve, fuel delivery valve and needle valve are the main source of high-frequency fluctuations.

A Wavelet-Based Diagnostic Framework for CRD Engine Injection Systems under Emulsified Fuel Conditions

The impact of the constituent oxides of nitrogen, carbon, sulphur, and other particulate matter which make up the gas emissions from diesel engines has motivated several control techniques for these pollutants. Water-in-diesel emulsions provide a reliable solution, but the wear effects on the fuel injection system (FIS) still pose remarkable concerns. Because pressure signals from the common rail (CR) reflect the dynamics associated with varying emulsion compositions and at varying engine RPMs, an investigative (and diagnostic) study was conducted on a KIA Sorento 2004 four-cylinder line engine at various water-in-diesel emulsion compositions and engine speeds. Alongside visual/microscopic inspections and spectral analyses, the diagnostic framework proposed herein functions on the use of standardized first-order differentials of the CR pressure signals to generate reliable continuous wavelet coefficients (CWCs) which capture discriminative spectral and transient information for accurate diagnosis. The results show that by extracting the CWCs from the first-order CR pressure differentials up to the 512th scale on a Mexican hat wavelet, adequate fault parameters can be extracted for use by a deep neural network (DNN) whose hyperparameters were globally optimized following a grid search. With a test accuracy of 92.3% against other widely-used ML-based diagnostic tools, the proposed DNN-based diagnostics tool was empirically assessed using several performance evaluation metrics.

An Explainable DL-Based Condition Monitoring Framework for Water-Emulsified Diesel CR Systems

Despite global patronage, diesel engines still contribute significantly to urban air pollution, and with the ongoing campaign for green automobiles, there is an increasing demand for controlling/monitoring the pollution severity of diesel engines especially in heavy-duty industries. Emulsified diesel fuels provide a readily available solution to engine pollution; however, the inherent reduction in engine power, component corrosion, and/or damage poses a major concern for global adoption. Notwithstanding, on-going investigations suggest the need for reliable condition monitoring frameworks to accurately monitor/control the water-diesel emulsion compositions for inevitable cases. This study proposes the use of common rail (CR) pressure differentials and a deep one-dimensional convolutional neural network (1D-CNN) with the local interpretable model-agnostic explanations (LIME) for empirical diagnostic evaluations (and validations) using a KIA Sorento 2004 four-cylinder line engine as a case study. CR pressure signals were digitally extracted at various water-in-diesel emulsion compositions at various engine RPMs, pre-processed, and used for necessary transient and spectral analysis, and empirical validations. Results reveal high model trustworthiness with an average validation accuracy of 95.9%.

Prediction model of injection quantity of high pressure common rail fuel system

Objectives In order to provide the basis for accurate control of diesel engine fuel injection quantity, a model method was proposed to establish the main injection quantity prediction model with input parameters as dwell time, common rail pressure and main injection pulse width for the pre-main injection mode. Methods AMESim simulation model was used to conduct simulation experiments and then collect data. Based on the data, the relationship between the dwell time and the main injection volume under single working condition was obtained. On this basis, the influence of common rail pressure and main injection pulse width on the model coefficient was introduced to build a complete multi-working condition main injection quantity prediction model. Multiple input parameter combinations were used to verify the accuracy and reliability of the prediction model of main injection quantity fluctuation. Results The results show that the root-mean-square error (RMSE)of the scheme of multi-working condition main injection quantity prediction model is 1.443 mm3. It can reduce the experiment amount required for modeling from n3orders of magnitude to n2orders of magnitude. Conclusions The proposed prediction model has sufficient accuracy, which is of great significance for engineering application of model-based fuel injection control.

Modelling Fuel Consumption andNOₓEmission of a Medium Duty Truck Diesel Engine With Comparative Time-Series Methods

This study focuses on different intelligent time series modelling techniques namely nonlinear autoregressive network with exogenous inputs (NARX), autoregressive integrated moving average with external inputs (ARIMAX), multiple linear regression (MLR), and regression error with autoregressive moving average (RegARMA), applied on a diesel engine to predict NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> emission and fuel consumption. The experiment data are collected from a six cylinder, four stroke medium duty truck diesel engine, which is integrated on a passenger bus and operated in engine integration tests. NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> emission and fuel consumption outputs are estimated with the help of input data; exhaust gas recirculation temperature and position, engine coolant temperature, engine speed, exhaust gas pressure, common rail pressure, intake manifold air temperature and pressure, accelerator pedal percentage, engine load, turbocharger variable geometry position and speed, and selective catalytic reduction outlet temperature. NARX artificial time series neural network, MLR, ARIMAX, and RegARMA time series techniques were separately applied for the estimation NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> emission and fuel consumption outputs. The performance of the models is analyzed and evaluated with Bayesian information criterion (BIC) and root mean square error (RMSE) criteria. When the high cost and time loss of experimental testing are thought, using the intelligent modelling methodology provides far more accurate prediction and fast application abilities to analyze internal combustion engine dynamics for the control and calibration manner. As a result of the comparison of different types of modelling techniques, RegARMA technique comes to the forefront with 6707.6 BIC value with 105.58 RMSE for NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> emission model and 4026.4 BIC value with 7.93 RMSE for fuel consumption model.

The Impact of Rotor Torques for the Pressure Ratio Characteristics of the Double Rotor Hydraulic Transformer

Serving as a core component, the performance of the hydraulic transformer (HT) directly affects the energy-saving performance of the common pressure rail (CPR) system. The HT is capable of both amplifying and reducing pressure without throttle loss, in which the pressure ratio is a critical parameter controlled through adjusting the torques acting on the rotors. However, our understanding of it relies on simplified models due to the complicated operation mechanism. This study focuses on the pressure ratio characteristics of the novel double rotor hydraulic transformer (DRHT). Firstly, the key influencing factors of the DRHT are acquired through theoretical analysis. Secondly, a dynamic model of the DRHT is established allowing for mechanical and fluid properties. Thirdly, a specially designed DRHT prototype is manufactured and the test bench is built up to verify the model. The experimental and numerical results show that the pressure ratio varies nonlinearly with the control angle especially when the control angle is greater than 10 degrees, while it changes almost linearly with the increasing rotating speed. The test results are consistent with the simulation results, which credit the mathematical model feasible and effective. The parametric study show that the augment of the A slot wrap angle on the valve plate could enhance the driving torque, as a result larger pressure ratio can be acquired. The enlargement of the B slot on the valve plate could make the variation of the pressure ratio more linearly. The current work is also significant for further design and the application of the DRHT.

Research on Rail Pressure Control of High-Pressure Common Rail System for Marine Diesel Engine Based on Controlled Object Model

The common rail pressure of a marine diesel engine high-pressure common rail system is typically controlled by a PID (Proportional Integral Differential) algorithm, which has problems with both overshoot and response delay. In this paper, the control method based on controlled object model for rail pressure is studied. The control model for a high-pressure common rail system is established within the controller. Through the developed control model and the current actual rail pressure obtained by real-time acquisition, the control variables issued by the controller to the controlled object are predicted and calculated. The fuel supply required in the whole high-pressure common rail system is calculated in advance, with the fuel supply then taken as the input value for the driving model in order to calculate the PWM control signal required by the high-pressure oil pump. A PWM control signal is used to control the proportional valve opening of the high-pressure oil pump, and then control the fuel pressure in the common rail pipe. In order to verify the correctness and control effects of the rail pressure control strategy based on controlled object model, a real-time simulation of the high-pressure common rail system has been developed by combining calculation equations with a MAP data query, which ensures real-time performance. At the same time, the real-time simulation of the high-pressure common rail system shows that the error between the simulation’s calculation and the actual test data is less than 5%, and thus model accuracy is guaranteed. The control method based on controlled object model is combined with the real-time simulation model for the high-pressure common rail system to verify the control strategy function, and the control effect is then compared with that of the PID control. Comprehensive verification shows that the control strategy based on controlled object model can significantly improve the response delay and overshoot of PID control.