Modal Analysis of Fuel Injection Systems and the Determination of a Transfer Function Between Rail Pressure and Injection Rate

2018 ◽  
Vol 140 (11) ◽  
Author(s):  
A. Ferrari ◽  
F. Paolicelli
Keyword(s):  
High Pressure ◽  
Transfer Function ◽  
Modal Analysis ◽  
Flow Rate ◽  
Fuel Injection ◽  
Injection System ◽  
Rail Pressure ◽  
Hydraulic Circuit ◽  
Lumped Parameter ◽  
Injection Apparatus

A detailed analysis of a common rail (CR) fuel injection system, equipped with solenoid injectors for Euro 6 diesel engine applications, has been performed in the frequency domain. A lumped parameter numerical model of the high-pressure hydraulic circuit, from the pump delivery to the injector nozzle, has been realized. The model outcomes have been validated through a comparison with frequency values that were obtained by applying the peak-picking technique to the experimental pressure time histories acquired from the pipe that connects the injector to the rail. The eigenvectors associated with the different eigenfrequencies have been calculated and physically interpreted, thus providing a methodology for the modal analysis of hydraulic systems. Three main modal motions have been identified in the considered fuel injection apparatus, and the possible resonances with the external forcing terms, i.e., pump delivered flow rate, injected flow rate, and injector dynamic fuel leakage through the pilot valve, have been discussed. The investigation has shown that the rail is mainly involved in the first two vibration modes. In the first mode, the rail performs a decoupling action between the high-pressure pump and the downstream hydraulic circuit. Consequently, the oscillations generated by the pump flow rates mainly remain confined to the pipe between the pump and the rail. The second mode is centered on the rail and involves a large part of the hydraulic circuit, both upstream and downstream of the rail. Finally, the third mode principally affects the injector and its internal hydraulic circuit. It has also been observed that some geometric features of the injection apparatus can have a significant effect on the system dynamics and can induce hydraulic resonance phenomena. Furthermore, the lumped parameter model has been used to determine a simplified transfer function between rail pressure and injected flow rate. The knowledge obtained from this study can help to guide designers draw up an improved design of this kind of apparatus, because the pressure waves, which are triggered by impulsive events and are typical of injector working, can affect the performance of modern injection systems, especially when digital rate shaping strategies or closely coupled multiple injections are implemented.

Fully predictive Common Rail fuel injection apparatus model and its application to global system dynamics analyses

2016 ◽  
Vol 18 (3) ◽  
pp. 273-290 ◽  
Author(s):  
Alessandro Ferrari ◽  
Pietro Pizzo
Keyword(s):  
High Pressure ◽  
Control System ◽  
Fuel Injection ◽  
Time History ◽  
Pressure Control ◽  
Rail Pressure ◽  
High Pressure Pump ◽  
Pressure Time ◽  
Pressure Control System ◽  
Injection Apparatus

A fully predictive model of a Common Rail fuel injection apparatus, which includes a detailed simulation of rail, pump, piping system, injectors and rail pressure control system, is presented and discussed. The high-pressure pump and injector sub-models have been validated separately and then coupled to the rail and pressure control system sub-models. The complete predictive model has been validated and applied to investigate the effects of the dynamics of each component of the injection apparatus on the rail pressure time history. Variable timing of the high-pressure pump delivery phases has also been considered, and the influence of this parameter on the injection performance has been analysed for both single- and multiple-injection events. Furthermore, the injection system dynamics during the transients between steady-state working conditions has been investigated in order to highlight the role played by the dynamic response of the pressure control system on the rail pressure time history.

Modeling and Control of a High Pressure Combined Air/Fuel Injection System

2009 ◽  
Author(s):  
Chao Yong ◽  
Eric J. Barth
Keyword(s):  
High Pressure ◽  
Fuel Injection ◽  
Lumped Parameter Model ◽  
Injection System ◽  
Fuel Injection System ◽  
Modeling And Control ◽  
Lumped Parameter ◽  
Mass Flow Rates ◽  
And Control ◽  
Liquid Piston

A high pressure combined air-fuel injection system is designed and tested for an experimental free liquid-piston engine compressor. The application discussed utilizes available high pressure air from the compressor’s reservoir, and high pressure fuel to mix and then inject into a combustion chamber. This paper addresses the modeling, design and control for this particular high-pressure air-fuel injection system, which features an electronically controlled air/fuel ratio control scheme. This system consists of a fuel line and an air line, whose mass flow rates are restricted by metering valves. These two lines are connected to a common downstream tube where air and fuel are mixed. By controlling the upstream pressures and the orifice areas of the metering valves, desired A/F ratios can be achieved. The effectiveness of the proposed system is demonstrated by a lumped-parameter model in simulation and validated by experiments.

Experimental study and optimization in the layouts and the structure of the high-pressure common-rail fuel injection system for a marine diesel engine

2020 ◽  
pp. 146808742092161
Author(s):  
Ying Hu ◽  
Jianguo Yang ◽  
Nao Hu
Keyword(s):  
High Pressure ◽  
Fuel Injection ◽  
Common Rail ◽  
Injection System ◽  
Rail Pressure ◽  
Common Rail System ◽  
Injection Volume ◽  
Rail System ◽  
Marine Diesel ◽  
High Pressure Common Rail

The structure and performance of the common-rail system for the marine diesel engine are different from those used for automobile applications, resulting from the larger accumulator volume and the single injection volume. According to the characteristics of the distributed structure of the accumulator volume, a novel optimisation idea to improve the steady-state performance of the high-pressure common-rail fuel injection system designed for a marine engine retrofitting is proposed. The study concentrates on the optimisation in the hydraulic layouts and the structure parameters to manage the energy stored in the pressure waves. First, the test rig was established to study and evaluate the steady-state performance of the high-pressure common-rail system. Second, the experiments of rail orders and injection sequences were carried out to study the influence of different hydraulic layouts on the energy distribution of pressure waves in the system. Meanwhile, a comprehensive and detailed model of the high-pressure common-rail system was built to investigate the structural parameters of a rail-to-injector pipe. Based on the high-pressure common-rail system model, the modified multi-objective genetic algorithm was employed to seek the trade-off between the consistency of the injection volume and the reduction of the rail pressure fluctuation. Results show that a uniform distribution of multiple rails in one cycle contributed to reducing the amplitude of the rail pressure oscillation. In the parameter ranges of this study, a longer length and larger diameter of the rail-to-injector pipe could reduce the standard deviation of the injection volume and the rail pressure fluctuation rate simultaneously.

Instantaneous torque, energy saving and flow rate ripple analysis of a common rail pump equipped with different delivery-pressure control systems

2017 ◽  
Vol 19 (10) ◽  
pp. 1036-1047 ◽  
Author(s):  
Alessandro Ferrari ◽  
Ruggero Vitali
Keyword(s):  
High Pressure ◽  
Energy Saving ◽  
Flow Rate ◽  
Control Strategy ◽  
Pressure Control ◽  
Common Rail ◽  
Injection System ◽  
Rail Pressure ◽  
High Pressure Pump ◽  
Rail Pressure Control

A mechanical model of a high-pressure pump of a common rail fuel injection system is presented and validated by comparison with experimental instantaneous pump shaft torque and pump piston lift data. The instantaneous torque has been measured with a high-performance torque meter installed on a hydraulic rig for testing pieces of injection apparatus. In the model, the mechanics of the piston plunger and the forces exchanged between pistons and cam are simulated, and friction losses between mobile parts are taken into account. The numerical tool is used to investigate the dynamical performance of the high-pressure pump and to analyse the impact of the rail pressure control strategy on instantaneous torque, energy saving and flow rate ripple. The rail pressure control strategy, based on the application of a fuel metering valve at the pump inlet, gives rise to an improved hydraulic efficiency of the injection system at part loads and to a moderate rate of pressure increase in the pumping chamber at part loads. However, the rail pressure control strategy based on the installation of a pressure control valve at one rail extremity leads to a reduction in the pump flow rate ripple and to a diminution in the fatigue stress. Furthermore, cavitation problems can occur during intake and early compression phases of the pump cycle when the fuel metering unit is working.

scholarly journals Rail Pressure Estimation for Fault Diagnosis in High Pressure Fuel Supply and Injection System

2019 ◽  
Vol 52 (15) ◽  
pp. 193-198
Author(s):  
Florian Hartl ◽  
Jonas Brueckner ◽  
Christoph Ament ◽  
Julian Provost
Keyword(s):  
High Pressure ◽  
Fault Diagnosis ◽  
Injection System ◽  
Rail Pressure ◽  
Fuel Supply ◽  
Pressure Estimation

scholarly journals Diagnostics of common rail components based on pressure curves in the fuel rail

2018 ◽  
Vol 173 (2) ◽  
pp. 3-8
Author(s):  
Mirosław KARCZEWSKI ◽  
Krzysztof KOLIŃSKI
Keyword(s):  
High Pressure ◽  
Fuel Injection ◽  
Dynamic Pressure ◽  
Common Rail ◽  
Injection System ◽  
Fuel Injector ◽  
Labview Software ◽  
Cr System ◽  
Data Acquisition Module ◽  
Pressure Changes

Majority of modern diesel engines is fitted with common-rail (CR) fuel systems. In these systems, the injectors are supplied with fuel under high pressure from the fuel rail (accumulator). Dynamic changes of pressure in the fuel rail are caused by the phenomena occurring during the fuel injection into the cylinders and the fuel supply to the fuel rail through the high-pressure fuel pump. Any change in this process results in a change in the course of pressure in the fuel rail, which, upon mathematical processing of the fuel pressure signal, allows identification of the malfunction of the pump and the injectors. The paper presents a methodology of diagnosing of CR fuel injection system components based on the analysis of dynamic pressure changes in the fuel rail. In the performed investigations, the authors utilized LabView software and a µDAC data acquisition module recording the fuel pressure in the rail, the fuel injector control current and the signal from the camshaft position sensor. For the analysis of the obtained results, ‘FFT’ and ‘STFT’ were developed in order to detect inoperative injectors based on the curves of pressure in the fuel rail. The performed validation tests have confirmed the possibility of identification of malfunctions in the CR system based on the pressure curves in the fuel rail. The ‘FFT’ method provides more information related to the system itself and accurately shows the structure of the signal, while the ’STFT’ method presents the signal in such a way as to clearly identify the occurrence of the fuel injection. The advantage of the above methods is the accessibility to diagnostic parameters and their non-invasive nature.

A High-Pressure Pulsed Water Jet Cutting System by Means of Water Hammer in a Convergent Pipeline

2003 ◽  
Author(s):  
Koji Yamane ◽  
Hiromitsu Sasaki ◽  
Yuzuru Shimamoto
Keyword(s):  
High Pressure ◽  
Fuel Injection ◽  
Injection Pressure ◽  
Water Jet ◽  
Injection System ◽  
Source Pressure ◽  
Electromagnetic Valve ◽  
Water Jet Cutting ◽  
Pulsed Water Jet ◽  
Cutting System

One of the authors has developed a high-pressure fuel injection system using an oil hammer for diesel engines in 1993. In the present study, we applied this novel principle of the fuel injection system to the water-jet cutting system, and a pulsed water jet cutting system by means of water hammer in convergent pipeline caused by strong spool acceleration was developed. The system consisted of a pump having a small size plunger and spool, a convergent pipeline, and automatic injector having a hole-type nozzle with a small orifice. This pump, generating strong compression waves at the convergent pipeline inlet by strong acceleration of spool and plunger, is controlled by the low source oil pressure and electromagnetic valve. The wave propagated in the convergent pipeline is dynamically intensified by water hammering in the pipeline. High pressure is then developed at the nozzle. The injection pressure and injection frequency are fully controllable by the source pressure, and by the valve-opening frequency of the electromagnetic valve (EMPV). A computer simulation demonstrated that an operation and the injection pressure are satisfactory as a water jet cutting system. It is shown that a pressure of 140 MPa is obtained in nozzle inlet by a source pressure of 11.8MPa in experiments. The dimension of the nozzle orifice was determined by visualizing the spray origin using a laser-sheet imaging technique. Stagnation force and its spectrum of water jet on work was measured to evaluate effects of injection period and standoff distance on punching time and area. Practical feasibility of water jet cutting system was demonstrated by cutting/punching tests for soft/no-heating materials or metal plates and by paint removing tests.

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