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Efficiency Prediction for Optimal Load Point Determination of Internal Combustion Engines in Hybrid Drives

Vienna University of Technology-Bastian Beyfuss, Peter Hofmann, Bernhard Geringer
Published 2019-09-09 by SAE International in United States
The efficiency of a Hybrid Electric Vehicle (HEV) strongly depends on its implemented Energy Management Strategy (EMS) that splits the driver’s torque request onto the Internal Combustion Engine (ICE) and Electric Motor (EM). For calibrating these EMS, usually, steady-state efficiency maps of the power converters are used. These charts are mainly derived from measurements under optimal conditions.However, the efficiency of ICEs fluctuates strongly under different conditions. Among others, these fluctuations can be induced by charge air temperature, engine oil temperature or the fuel’s knock resistance.This paper proposes a new approach for predicting the impact of any external influence onto the ICE efficiency. This is done by computing the actual deviation from the optimal reference ignition timing and adjusting the result by actual oil temperature and target air-to-fuel ratio.For calibration, only a fuel consumption map, measured under random conditions, and some warm-up measurements are required. The efficiency prediction is evaluated by measurements from the engine test bench.Due to the real time capability of this method, the integration into any HEV EMS is possible. By considering this…
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A Study on Combustion Characteristics of a High Compression Ratio SI Engine with High Pressure Gasoline Injection

Mazda Motor Corp-Takashi Youso, Tatsuya Fujikawa, Masahisa Yamakawa
Waseda Univ-Takashi Kaminaga, Kyohei Yamaguchi, Sok Ratnak, Jin Kusaka
Published 2019-09-09 by SAE International in United States
In order to improve thermal efficiency of spark ignition (SI) engines, an improved technology to avoid irregular combustion under high load conditions of high compression ratio SI engines is required. In this study, the authors focused on high pressure gasoline direct injection in a high compression ratio SI engine, which its rapid air-fuel mixture formation, turbulence, and flame speed, are enhanced by high-speed fuel spray jet. Effects of fuel injection pressure, injection and spark ignition timing on combustion characteristics were experimentally and numerically investigated. It was found that the heat release rate was drastically increased by raising the fuel injection pressure. The numerical simulation results show that the high pressure gasoline direct injection enhanced small-scale turbulent intensity and fuel evaporation, simultaneously. These two effects were considered as the main factors to increase the flame propagation speed, suggesting a new combustion concept different from conventional SI combustion controlled by in-cylinder bulk flow. This combustion method enables the delay of fuel injection and spark ignition timing up to near top dead center (TDC) which leads to avoid…
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Experimental Studies of the Effect of Ethanol Auxiliary Fueled Turbulent Jet Ignition in an Optical Engine

SAE International Journal of Engines

Brunel University, UK-Khalifa Bureshaid, Ray Shimura, Hua Zhao
MAHLE Powertrain, LLC, USA-Mike Bunce
  • Journal Article
  • 03-12-04-0026
Published 2019-07-26 by SAE International in United States
Internal combustion (IC) engines are widely used in automotive, marine, agricultural and industrial machineries because of their superior performance, high efficiency, power density, durability and versatility in size and power outputs. In response to the demand for improved engine efficiency and lower CO2 emissions, advanced combustion process control techniques and more renewable fuels should be adopted for IC engines. Lean-burn combustion is one of the technologies with the potential to improve thermal efficiencies due to reduced heat loss and higher ratio of the specific heats. In order to operate the IC engines with very lean air/fuel mixtures, multiple turbulent jet pre-chamber ignition has been researched and developed to extend the lean-burn limit. Turbulent Jet Ignition (TJI) offers very fast burn rates compared to spark plug ignition by producing multiple ignition sites that consume the main charge rapidly. In this research, studies were carried out on the ignition and combustion characteristics of pre-chamber ignition produced by a Mahle TJI unit installed in a single-cylinder engine with optical access. In particular, this article focuses on the spatial…
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Knock and Pre-Ignition in Spark-Ignition Engine Fuelled by Different Blends of Jojoba Bio-Gasoline with Kerosene

Helwan University-M.S. Radwan, Youssef A. Attai, Y.I. Hassan
Published 2019-05-17 by SAE International in United States
In the present article, the knock tendency and pre-ignition resistance (PIR) were determined experimentally for different blends of kerosene and jojoba bio-gasoline. The effects of varying equivalence ratios, rotational speed, inlet air temperature and pressure, and ignition timing on knock tendency and PIR were investigated. The influence of compression ratio on PIR was also studied. Jojoba bio-gasoline was synthesized using transesterification method through performing a chemical reaction between well-stirred jojoba raw oil and alcohol. Experiments were carried out on a Ricardo E6/MS variable compression ratio spark-ignition (SI) engine fuelled by jojoba bio-gasoline/kerosene blends of volumetric percentages of 0%, 5%, 10%, 15%, and 20% jojoba bio-gasoline. The onset of pre-ignition and knock were detected by observing the pressure oscillations using a piezoelectric pressure transducer, a synchronizing magnetic sensor, and a degree-marking probe. The results showed that increasing the percentage of bio-gasoline in the blends with kerosene leads to a significant increase in PIR and a remarkable decrease in the knock tendency. This will lead to the design of a more efficient engine by increasing its compression…
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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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A Visual Investigation of CFD-Predicted In-Cylinder Mechanisms That Control First- and Second-Stage Ignition in Diesel Jets

Sandia National Laboratories-Mark Musculus
University of Wisconsin-Rolf Reitz
Published 2019-04-02 by SAE International in United States
The long-term goal of this work is to develop a conceptual model for multiple injections of diesel jets. The current work contributes to that effort by performing a detailed modeling investigation into mechanisms that are predicted to control 1st and 2nd stage ignition in single-pulse diesel (n-dodecane) jets under different conditions. One condition produces a jet with negative ignition dwell that is dominated by mixing-controlled heat release, and the other, a jet with positive ignition dwell and dominated by premixed heat release.During 1st stage ignition, fuel is predicted to burn similarly under both conditions; far upstream, gases at the radial-edge of the jet, where gas temperatures are hotter, partially react and reactions continue as gases flow downstream. Once beyond the point of complete fuel evaporation, near-axis gases are no longer cooled by the evaporation process and 1st stage ignition transitions to 2nd stage ignition. At this point, for the positive ignition dwell case, all of the fuel has already been injected and the 2nd stage ignition zone is surrounded by a relatively large mass of…
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Effect of Injection Timing on the Ignition and Mode of Combustion in a HD PPC Engine Running Low Load

Lund University-Christian Ibron, Mehdi Jangi, Sara Lonn, Alexios Matamis, Oivind Andersson, Martin Tuner, Mattias Richter, Xue-Song Bai
Published 2019-04-02 by SAE International in United States
This work aims to study the effect of fuel inhomogeneity on the ignition process and subsequent combustion in a compression ignition Partially Premixed Combustion (PPC) engine using a primary reference fuel (PRF) in low load conditions. Five cases with injection timings ranging from the start of injection (SOI) at -70 crank angle degrees (CAD) to -17 CAD have been studied numerically and experimentally in a heavy duty (HD) piston bowl geometry. Intake temperature is adjusted to keep the combustion phasing constant. Three dimensional numerical simulations are performed in a closed cycle sector domain using the Reynolds Averaged Navier-Stokes (RANS) formulation with k-ϵ turbulence closure and direct coupling of finite rate chemistry. The results are compared with engine experiments. The predicted trends in required intake temperature and auto-ignition location for a constant combustion phasing are consistent with experiments. The simulations show that the auto-ignition is critically dependent on both fuel and temperature stratification. The ignition occurs in fuel-lean regions but the mixing of the fuel with the cylinder gas and the cylinder gas temperature stratification (prior…
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Particle Reduction in LPG Lean Stratified Combustion by Intake Strategies

Korea Advanced Institute of Science & Technology-Sanguk Lee, Sangjae Park, Choongsik Bae
Published 2019-04-02 by SAE International in United States
Lean stratified combustion shows high potential to reduce fuel consumption because it operates without the intervention of a throttle valve. Despite its high fuel economy potential, it emits large amounts of particulate matter (PM) because the locally rich mixture is formed at the periphery of a spark plug. Furthermore, the combustion phasing angle is not realized at MBT ignition timing, which can bring high work conversion efficiency. Since PM emission and work conversion efficiency are in a trade-off relation, this research focused on reducing PM emission through achieving high work conversion efficiency. Two intake air control strategies were examined in this research; throttle operation and late intake valve closing (LIVC). The experiment was conducted in a single cylinder spray-guided direct injection spark ignition (SG-DISI) engine with liquefied petroleum gas (LPG). The injected fuel amount was fixed so as to investigate the effect of each strategy. The throttle valve strategy decreased the filter smoke number (FSN) as the restriction of inhaled air was increased. By contrast, the number of particles was increased. When the LIVC strategy…
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Research of Knocking Deterioration due to Accumulated Carbon Deposits on Piston Surfaces

SOKEN, INC-Kazuo Sunami
Toyota Motor Corporation-Takayuki Hosogi, Rihito Kaneko, Hisayuki Ito
Published 2019-04-02 by SAE International in United States
The quantity of heavy components in fuel is increasing as automotive fuels diversify, and engine oil formulations are becoming more complex. These trends result in the formation of larger amounts of carbon deposits as reaction byproducts during combustion, potentially worsening the susceptibility of the engine to knock [1]. The research described in this paper aimed to identify the mechanism that causes knocking to deteriorate due to carbon deposits in low to medium engine load ranges, which are mainly used when the vehicle drives off and accelerates. With this objective, the cylinder temperature and pressure with and without deposits were measured, and it was found that knocking deteriorates in a certain range of ignition timing. Additionally, this paper reports the results of an investigation into the relationship between the rate at which the ignition is retarded by the knocking control system (KCS) and the time required to eliminate knocking; this was carried out to help formulate a control plan to resolve the effects of knocking deterioration.
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Combustion Characterization of Methanol in a Lean Burn Direct Injection Spark Ignition (DISI) Engine

Ghent University-Duc-Khanh Nguyen, Bram Stepman, Viktor Vergote, Louis Sileghem, Sebastian Verhelst
Published 2019-04-02 by SAE International in United States
Lean operation is a promising approach to increase the engine efficiency. One of the main challenges for lean-burn technology is the combustion instability. Using a high laminar burning velocity fuel such as methanol might solve that problem. The potential of lean-burn limit extension with methanol was investigated through a comparison with conventional gasoline. In this work, a direct injection turbocharged SI engine was operated at wide open throttle (WOT), with the load controlled by a lean-burn strategy. The amount of fuel was decreased (or lambda increased) until the combustion became unstable. For methanol, the lambda limit was about 1.5, higher than the lambda limit for gasoline which was only about 1.2. The brake thermal efficiency for methanol increased as lambda increased and reached its peak at ~41% in a lambda range of 1.2-1.4. Then, the efficiency decreased as lambda increased.The increase of lambda also causes a change in the combustion process, e.g. prolonged flame development period (CA0-10). The relationship between the combustion characteristics and the combustion instability of methanol under lean-burn condition has not been…
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