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Gasoline Fueled Pre-chamber Ignition System for a Light-Duty Passenger Car Engine with Extended Lean Limit

SAE International Journal of Engines

Technische Universitat München, Germany-Andreas Stadler, Maximilian Wessoly, Sebastian Blochum, Martin Härtl, Georg Wachtmeister
  • Journal Article
  • 03-12-03-0022
Published 2019-06-07 by SAE International in United States
In this work, a light-duty research engine based on a passenger car engine is equipped with an in-house developed pre-chamber (PC) ignition system replacing the conventional spark plug. By using such kind of ignition system, the combustion in the main chamber is enhanced by radical seeding through jets travelling from the pre-chamber to the main chamber. These radicals serve as high-energy ignition sites for the mixture in the main combustion chamber leading to enhanced burn rates and combustion speed. In contrast to conventional spark-ignited combustion starting from the spot of the electrode gap, an extended lean misfire limit and a mitigated knocking tendency are achieved. The presence of a gasoline direct injector inside the PC enables the system to operate in both passive and active modes. The injection of a small fuel amount allows separating the air-to-fuel equivalence ratio of the pre-chamber and the main chamber. By this, an overall lean mixture is ignited by providing a stoichiometric mixture near the PC spark plug. In this study, different orifice nozzles of the PC are investigated…
 
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Experimental Studies on Liquid Phase LPG Direct Injection on a Two-Stroke SI Engine

SAE International Journal of Engines

Indian Institute of Technology Madras, India-Adwitiya Dube, M. Vivekanand, A. Ramesh
  • Journal Article
  • 03-12-03-0023
Published 2019-05-31 by SAE International in United States
Directly injecting fuel in two-stroke spark-ignition (2S-SI) engines will significantly reduce fuel short-circuiting losses. The liquid phase liquefied petroleum gas (LPG) DI (LLDI) mode has not been studied on 2S-SI engines even though this fuel is widely used for transportation. In this experimental work a 2S-SI gasoline-powered engine used on three-wheelers was modified to operate in LLDI mode with an electronic engine controller. The influences of injection pressure (IP), end of injection (EOI) timing, location of the spark plug, and type of injector on performance, combustion, and emissions were studied at different operating conditions. EOI close to bottom dead center with the spark plug located near the exhaust port was the most suitable for the LLDI mode which significantly enhanced the fuel trapping efficiency and improved the thermal efficiency. At 70% throttle condition the brake thermal efficiency increased from 19% to 25.6% and there was an 87% reduction in hydrocarbon (HC) emission compared to liquid phase LPG manifold injection. The use of multi-hole injector extended the maximum power output due to better in-cylinder mixture formation,…
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SAE STANDARDS NEWS

Automotive Engineering: May 2019

an SAE member on the GFISC, wrote this article for SAE Standards News. A retired General Motors fuel systems/powertrain engineer, Mr. Glennan is a technical writer for Technical Writing Solutions, LLC.-Thomas B. Glennan
  • Magazine Article
  • 19AUTP05_08
Published 2019-05-01 by SAE International in United States

Today's fuel injection engineers, designers, and researchers are continually challenged to meet increasingly demanding fuel economy, emissions and performance requirements for gasoline engine-powered vehicles. The availability of established and recognized standards in support of this effort is critical to accomplishing these goals. And the work of SAE's Gasoline Fuel Injection Standards Committee (GFISC) to create and maintain these essential standards, guidelines and recommended practices helps to ensure the success of these efforts.

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Dispenser Nozzle Spouts for Liquid Fuels Intended for Use with Spark Ignition and Compression Ignition Engines

Fuel Systems Standards Committee
  • Ground Vehicle Standard
  • J285_201904
  • Current
Published 2019-04-29 by SAE International in United States
This SAE Recommended Practice provides standard dimensions for liquid fuel dispenser nozzle spouts and a system for differentiating between nozzles that dispense liquid fuel into vehicles with spark ignition (SI) engines and compression ignition (CI) engines for land vehicles. Current legal definitions only distinguish between “Unleaded Fuel” and “All Other Types of Fuel.” These definitions are no longer valid. This document establishes a new set of definitions that have practical application to current automobile liquid fuel inlets and liquid fuel dispenser nozzle spouts.
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A Novel Laminar Flame Speed Correlation for the Refinement of the Flame Front Description in a Phenomenological Combustion Model for Spark-Ignition Engines

SAE International Journal of Engines

University of Naples Federico II, Italy-Vincenzo De Bellis, Enrica Malfi, Luigi Teodosio
University of Udine, Italy-Pietro Giannattasio, Fabio Di Lenarda
  • Journal Article
  • 03-12-03-0018
Published 2019-04-25 by SAE International in United States
This work focuses on the effects of the laminar flame speed (LFS) and flame stretch on the phenomenological modeling of the combustion process in spark ignition engines. The study is carried out using a 1D model of a small-size naturally aspirated SI engine, equipped with an external EGR circuit. The model, developed in GT-Power™ environment, includes advanced sub-models of the in-cylinder processes. The combustion is modeled using a fractal approach, where the burning rate is directly related to the laminar flame speed. A novel LFS correlation based on 1D chemical kinetics computations is presented and assessed with the experimentally derived Metghalchi and Keck correlation. Moreover, the effects of the flame stretch, evaluated according to an asymptotic theory, are properly considered in the combustion model. In order to verify the consistency and accuracy of the present approach, the model predictions are compared with the results of experimental tests performed at full- and part-load engine operations, with and without the activation of the EGR device. The proposed LFS correlation provides more accurate results than the Metghalchi and…
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Misfire Generator Functional Requirements

Vehicle E E System Diagnostic Standards Committee
  • Ground Vehicle Standard
  • J2901_201904
  • Current
Published 2019-04-11 by SAE International in United States
The intent of the specification is to present a functional set of requirements which define the user and hardware interfaces while providing sufficient capability to meet the misfire patterns for compliance demonstration and engineering development. Throughout this requirement, any reference to “ignition or injector control signal” is used interchangeably to infer that the effected spark ignition engine’s ignition control signal or the compression ignition engine’s injector control signal is interrupted, timing phased, or directly passed by the misfire generator. For spark ignition engines, the misfire generator behaves as a spark-defeat device which induces misfires by inhibiting normal ignition coil discharge. It does so by monitoring the vehicle’s ignition timing signals and suspends ignition coil saturation for selected cylinder firing events. The misfire generator will thereby induce engine misfire in spark ignited gasoline internal combustion engines; including rotary engines. For compression ignition engines, the misfire generator behaves as a fuel injection-defeat device which induces misfire by inhibiting the normal fuel injection pulses. It does so by monitoring the injection pulses signal and suspending the injection pulses…
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Comparison between Pressure- and Ion-Current-Based Closed-Loop Combustion Control Performance

SAE International Journal of Engines

Alma Automotive srl, Italy-Andrea Businaro
Ferrari Auto spa, Italy-Ruggero Cevolani
  • Journal Article
  • 03-12-02-0016
Published 2019-04-08 by SAE International in United States
Combustion control is key for achieving maximum efficiency in internal combustion engines. For SI (spark-ignition) engines, knocking combustions occurrence can be controlled using a protective closed-loop control system, but additional information, such as combustion angular phase, is needed to minimize brake-specific fuel consumption in the entire engine operating range. The proposed solution is a closed-loop Spark Advance (SA) controller based on pre-defined combustion phase targets, able to react to excessive knocking levels. Pressure- and ion-current-based combustion closed-loop control are compared in the article, by implementing both solutions in Model-In-the-Loop environment and then in real time. Both controllers are characterized by an aggressive strategy, which pursues the optimal combustion angular phase, and by a protective action governed by measured knocking levels. Experimental tests carried out at the engine test bench demonstrate the possibility of using the ionization current signal as the main input to a closed-loop combustion controller, both in knock-free and knock-limited conditions: the considered indicators (mean values and standard deviation of the controlled variables) to estimate the controller performance while using the pressure or…
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Combined Benefits of Variable Valve Actuation and Low-Pressure EGR on SI Engine Efficiency Part 1: Part Load

Southwest Research Institute-Yanyu Wang, Graham Conway, Chris Chadwell
Published 2019-04-02 by SAE International in United States
Modern spark ignited engines face multiple barriers to achieving higher thermal efficiency. This study investigated the potential of utilizing both continuously variable valve actuation (VVA) and low-pressure cooled exhaust gas recirculation (EGR) to improve engine thermal efficiency at part-load conditions. Six speed / load points were investigated on a 1.6 L turbocharged gasoline direct injection engine. A design of experiment (DoE) approach using the Box-Behnken surface response model was conducted. The DoE results revealed different brake specific fuel consumption (BSFC) responses to the valve phasing and the intake valve lift at different operating conditions. Further engine testing was carried out at each speed / load point to confirm the engine efficiency and combustion performance when targeting different valvetrain controls and EGR strategies. The results indicated that utilizing the VVA system could always reduce BSFC at the studied operating conditions. The BSFC reduction was attributed to reduced pumping and incomplete combustion losses. The reduction in losses was attributed to optimizing the amount of hot trapped residuals compared with the fixed valve configuration, and load control through…
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SI Engine Combustion and Knock Modelling Using Detailed Fuel Surrogate Models and Tabulated Chemistry

AVL Dacolt BV-Dmitry Goryntsev, Ferry Tap
AVL List GmbH-Mijo Tvrdojevic, Peter Priesching
Published 2019-04-02 by SAE International in United States
In the context of today’s and future legislative requirements for NOx and soot particle emissions as well as today’s market trends for further efficiency gains in gasoline engines, computational fluid dynamics (CFD) models need to further improve their intrinsic predictive capability to fulfill OEM needs towards the future. Improving fuel chemistry modelling, knock predictions and the modelling of the interaction between the chemistry and turbulent flow are three key challenges to improve the predictivity of CFD simulations of Spark-Ignited (SI) engines. The Flamelet Generated Manifold (FGM) combustion modelling approach addresses these challenges. By using chemistry pre-tabulation technologies, today’s most detailed fuel chemistry models can be included in the CFD simulation. This allows a much more refined description of auto-ignition delays for knock as well as radical concentrations which feed into emission models, at comparable or even reduced overall CFD run-time. The FGM model has a high level of intrinsic predictive capability, as already demonstrated for many academic cases as well as for industrial burners, gas turbines and diesel engines. The application to gasoline engines has…
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Spark Mechanism in High Speed Flow

Michigan Technological University-Mary P. Zadeh, Henry Schmidt, William Atkinson, Jeffrey Naber
Published 2019-04-02 by SAE International in United States
An experimental study was performed to investigate spark ignition and subsequent spark stretch evolution in an inert environment at high- flow velocities up to 32 m/s across the spark plug gap in a constant-volume optical combustion-vessel at pressures representative of those in an engine. The vessel is capable of generating various in-cylinder thermodynamic conditions representative of light-duty spark ignition engines. The characteristic behavior of the spark was investigated using both a high-speed optical diagnostics and electrical measurement. Charge gas pressures were varied from 15 to 45 bar. Results show that the spark, flowing downstream the spark plug, is subject to short circuits of the spark channel and/or restrikes. The frequency of the restrike increased with increased flow velocity and charge gas pressure and decreased discharge current level. The position of the ground electrode with respect to the flow and the gap size, as well as the flow velocity and charge gas pressure, were determined to have a significant influence on spark plasma development and electrical discharge prediction. It was observed that a wider spark plug…
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