Modal Analysis as a Design Tool for Dynamical Optimization of Common Rail Fuel Injection Systems

Ferrari, Alessandro; Paolicelli, Federica

doi:10.4271/2015-24-2467

Cited by 4 publications

(5 citation statements)

References 19 publications

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“…The standard fuel dosing control strategies, both for single and multiple injections, are based on the rail-mounted pressure sensor, which does not contain the information of pressure oscillations. Especially for pilot injections, when the requested fuel mass is very low (m inj ~ 1 mg/str) and DT < 2500 μs, the presence of the pressure oscillations modifies the second pulse injected mass, generating remarkable differences between the requested and effective total injected fuel [35,36,45]. Thus a fuel quantity FQC becomes crucial to manage gasoline PPC using a CR system, whereby the energy released by pilot injections plays a key role in ensuring the whole combustion process stability [14,15,16,17,46,47,48].…”

Section: Fuel Quantity Fqcmentioning

confidence: 99%

“…Despite the high flexibility performing multiple injections with CR systems, hydrodynamic effects, which are generated by the water hammer consequent to the injector nozzle closing after each injection, affect the actual quantity of fuel injected during the following injections [26,27,28,29,30,31,32], especially when the amount of fuel injected is very low (in the range of 1 mg/str) and the relative distance between injections is small (lower than 2000 μs). As widely discussed in the literature [33,34,35,36,37,38,39,40,41,42,43], due to the propagation of pressure waves, the mass of fuel injected during the second of two consecutive injection pulses may vary significantly (up to 50%) around the nominal value, producing negative effects on the gasoline PPC stability [25,37]. Thus a fuel quantity correction strategy is required to achieve accurate fuel injection management.…”

mentioning

confidence: 99%

“…Su et al [39] experimentally obtained an ideal filter for the elimination of the water hammer. Gupta et al [40], Bianchi et al [31,41], and Ferrari et al [32,35,38] showed that water hammer effects can be reduced by changing the system layout but increasing the cost of designing and manufacturing of the whole injection system. Bai et al [37] presented a correction strategy based on the reconstruction of injected quantity oscillations, for a typical pilot-main injection strategy, without taking into account the source of this phenomenon, i.e., pressure waves.…”

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confidence: 99%

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Development of a Predictive Pressure Waves Model for High-Pressure Common Rail Injection Systems

Silvagni¹,

Ravaglioli²,

Ponti³

et al. 2021

SAE Int. J. Engines

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Over the last years, automotive industries drove a great amount of research in the field of advanced combustion techniques minimizing carbon dioxide emissions. The so-called Low-Temperature Combustions (LTC), characterized by the self-ignition of highly premixed air-fuel mixtures, represent a promising solution to achieving high efficiency and ultralow emissions of nitrogen oxides (NOx) and particulate matter. Among these, gasoline Partially Premixed Combustion (PPC), obtained through the high-pressure direct injections of gasoline, showed a good potential for the simultaneous reduction of pollutants and emissions in compression ignited engines. However, when multiple injections per cycle are performed (with hydraulic-assisted needle opening), combustion stability might be compromised by the wave effects in the hydraulic system, which produce incoherence between the requested and injected fuel. This work presents a model-based pressure waves reconstruction strategy, based on a control-oriented model of the high-pressure common rail injection system fueled with gasoline. To determine the hydraulic system's behavior during the injection process, a specifically designed flushing bench with a high-frequency acquisition system has been developed. Experimental activities have been carried out to highlight fuel pressure fluctuations with single and double injection patterns. Through the analysis of the acquired data, the key parameters (characteristic of the system) have been identified and the accuracy of pressure waves reconstruction has been evaluated, always returning errors lower than 2% between measured and estimated instantaneous pressures. Different fuel types, injectors, and rail positions have been tested to highlight the robustness of the approach. Based on the instantaneous pressure trace estimated with the control-oriented model, a fuel quantity Fluctuation Correction Strategy (FQC), implementable on a standard engine Electronic Control Unit (ECU), has been developed. The obtained results confirm the potential to reduce fuel quantity oscillations in multiple-injections systems.

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Section: Fuel Quantity Fqcmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Development of a Predictive Pressure Waves Model for High-Pressure Common Rail Injection Systems

Silvagni¹,

Ravaglioli²,

Ponti³

et al. 2021

SAE Int. J. Engines

View full text Add to dashboard Cite

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“…39 This study uses a lumped-parameter approach to describe the dynamics from a hydraulic perspective. Ferrari and Paolicelli 40 also used this method to analyse a CR fuel system model. Figure 3 shows the simplified CR model and its connection with the injector.…”

Section: Rail Pressure Variation Analysis and Algorithm For High-pres...mentioning

confidence: 99%

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

Lei

Qiu

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part D:

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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.

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“…The high-pressure hydraulic circuit of the tested CR fuel injection system (Figure 1 The high-pressure circuit of the CR system has been simulated by means of a linear time invariant (LTI), lumped parameter model, which was previously developed. 17 The injection apparatus has basically been schematized, from a hydraulic point of view, as a network of zero-dimensional chambers (cf. Figure 2 and also Figure 1) in which the pressure is supposed to be uniform and can only vary with respect to time.…”

Section: Model Descriptionmentioning

confidence: 99%

Determination of the transfer function between the injected flow-rate and high-pressure time histories for improved control of common rail diesel engines

Ferrari

Salvo

2016

International Journal of Engine Research

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Theoretical and experimental methodologies have been proposed and illustrated to determine the transfer function between the injected flow-rate and the rail pressure for common rail injection systems. An analytical transfer function has been calculated in the frequency domain, utilizing a previously developed lumped parameter model of the overall hydraulic layout of a common rail system. The predicted transfer function has been compared, in a Bode diagram, with an experimental estimation of the transfer function, based on the measured rail pressure and injected flow-rate time histories that were acquired at the hydraulic rig for different working conditions. The experimental estimation of the transfer function has been worked out by applying a selective spectral technique in order to reduce the effects of measurement noise on the rail pressure and injected flow-rate time histories. The accuracy of the model-derived transfer function has been improved significantly by integrating a pressure control system sub-model, which includes the action of the electronic control unit on the rail pressure time history through the pressure regulator, in the hydraulic model of the common rail circuit. Finally, the time histories of the rail pressure, predicted by means of the complete injection apparatus model, have been compared with the corresponding experimental traces at different working conditions and a very satisfactory agreement has in general been found. The methodologies proposed for the accurate evaluation of the transfer function between the injected flow-rate and the rail pressure time histories can be applied to diesel engines in order to implement innovative closed-loop strategies for the injected mass control.

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Modal Analysis as a Design Tool for Dynamical Optimization of Common Rail Fuel Injection Systems

Cited by 4 publications

References 19 publications

Development of a Predictive Pressure Waves Model for High-Pressure Common Rail Injection Systems

Development of a Predictive Pressure Waves Model for High-Pressure Common Rail Injection Systems

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

Determination of the transfer function between the injected flow-rate and high-pressure time histories for improved control of common rail diesel engines

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