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The Virtual Engine Development for Enhancing the Compression Ratio of DISI-Engines by Means of Water Injection and Variable Valve Timing

FKFS-Antonino Vacca, Francesco Cupo, Marco Chiodi, Michael Bargende
Ford Werke GmbH-Oliver Berkemeier, Maziar Khosravi
  • Technical Paper
  • 2020-37-0010
To be published on 2020-06-23 by SAE International in United States
With the aim of significantly reducing emissions, while keeping CO2 production under control, gasoline engines are faced with a new challenge to survive the constraints imposed by the RDE cycles. Current downsized engines are developed with the most recent techniques for increasing efficiency, such as high direct injection pressure, selective valve actuation, variable turbine geometry, and innovative thermal management system. The factor limiting their further step towards enhanced efficiency is the onset of abnormal combustion process. Therefore the challenge for the further boost of modern engine efficiency is the improvement of the combustion process. Different combustion technics such as HCCI and the employment of pre-chamber have been investigated, but the possibility of effectively use them in a wide range of the engine map, by fulfilling at the same time the needing of fast load control are still limiting their dissemination. For these reasons the technologies for improving the characteristics of a standard combustion process are still deeply investigated. Among these water injection in combination with either early or late intake valve closing offers the possibility…
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Fault Diagnosis of an Engine through Analyzing Vibration Signals on the Block

Hyundai Motor Group-Jaemin Jin, Insoo Jung
Kookmin University-Sung-Hwan Shin PhD
  • Technical Paper
  • 2020-01-1568
To be published on 2020-06-03 by SAE International in United States
Unpredictable faults oriented from ambiguous reasons could occur in an engine of a vehicle. However, there are some symptoms from which an engine is working abnormally before the engine is stalled by faults. In this paper, methods for diagnosis of engine faults by using vibrations are proposed. Through bench tests, to extract features for fault diagnosis, various samples with normal and abnormal conditions are prepared and vibration signals from the block of an engine are measured and analyzed. To consider cost and performance of a sensor, vibrations from a knock sensor signal as well as accelerometers are analyzed. Measured vibration signals are synchronized with signal of the crank position sensor and analyzed to detect which event is involved. Modulation analysis and Hilbert transform are applied to extract features representing the symptoms of engine faults and to indicate when the abnormal event happens, respectively. As a result, the mean value of modulation indexes at modulated frequencies called as the half order modulation index (HOMI) is a factor determining if an engine is abnormal and envelope of…
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Influence of Port Water Injection on the Combustion Characteristics and Exhaust Emissions in a Spark-Ignition Direct-Injection Engine

Shanghai Jiao Tong University-Yadong Fan, Tianbao Wu, Xuesong Li, Min Xu, David Hung
  • Technical Paper
  • 2020-01-0294
To be published on 2020-04-14 by SAE International in United States
It is well known that engine downsizing is still the main energy-saving technology for spark-ignition direct-injection (SIDI) engine. However, with the continuous increase of the boosting ratio, the gasoline engine is often accompanied by the occurrence of knocking, which has the drawback to run the engine at retarded combustion phasing. Besides, in order to protect the turbine blades from being sintered by high exhaust temperature, the strategies of fuel enrichment are often taken to reduce the combustion temperature, which ultimately leads to a high level of particulate number emission. Therefore, to address the issues discussed above, the port water injection (PWI) techniques on a 1.2-L turbocharged, three-cylinder, SIDI engine were investigated.Measurements indicate that the optimization of spark timing has a significant impact on its performance. The two factors of the water substance itself and spark advance caused by the knock mitigation are trade-offs, which eventually affect the combustion performance. Under knock limited spark advance (KLSA) condition, we find that the application of port water injection could effectively advance the combustion phasing and reduce exhaust gas…
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On Maximizing Argon Engines' Performance via Subzero Intake Temperatures in HCCI Mode at High Compression Ratios

King Abdullah University of Science & Technology-Ali Elkhazraji, Abdulrahman Mohammed, Sufyan Jan, Jean-Baptiste Masurier, Robert Dibble, Bengt Johansson
  • Technical Paper
  • 2020-01-1133
To be published on 2020-04-14 by SAE International in United States
The improvement of the indicated thermal efficiency of an argon power cycle (replacing nitrogen with argon in the combustion reaction) is investigated in a CFR engine at high compression ratios in homogeneous charge compression ignition (HCCI) mode. The study combines the two effects that can increase the thermodynamic efficiency as predicted by the ideal Otto cycle: high specific heat ratio (provided by argon), and high compression ratios. However, since argon has relatively low heat capacity (at constant volume), it results in high in-cylinder temperatures, which in turn, leads to the occurrence of knock. Knock limits the feasible range of compression ratios and further increasing the compression ratio can cause serious damage to the engine due to the high pressure rise rate caused by advancing the combustion phasing. The technique proposed in this study in order to avoid intense knock of an argon cycle at high compression ratios is to cool the intake charge to subzero temperatures which leads to lower in-cylinder temperatures and hence, less possibility of having knock. The main variable in this study…
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Impact of Engine Oil Detergent on Low Speed Pre-Ignition (LSPI) and Fuel Economy Performance

Afton Chemical Corp.-Ashutosh Gupta, Mark Devlin
  • Technical Paper
  • 2020-01-1424
To be published on 2020-04-14 by SAE International in United States
Low Speed Pre-Ignition (LSPI), also referred to as Stochastic Pre-Ignition (SPI), Superknock or Megaknock is an undesirable combustion phenomenon that limits the fuel economy, drivability, emissions and durability performance of modern turbocharged gasoline engines. Numerous studies have previously reported that the frequency of LSPI is sensitive to engine oil composition. One of these drivers is the concentration of Calcium, which is usually delivered in the form of a detergent in the additive package. Switching to completely all-Magnesium detergent and/or severely limiting the concentration of Ca in the engine oil have recently been proposed as potential means to reduce LSPI. In this work, we evaluate the impact of detergent type on LSPI performance as well as on other performance that the modern engine oil needs to deliver. Particularly the impact of detergent type on Fuel Economy performance is evaluated. To ensure a rigorous and high precision measurement of the impact of engine oil on fuel economy, representative of real-world conditions, under well-controlled conditions, the ASTM D8114 test (Sequence VIE) was used to quantify fuel economy performance…
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Numerical Investigations on Strong Knocking Combustion under Advanced Compression Ignition Conditions

State Key Lab of Engines-Jiaying Pan
Tianjin University-Lin Chen, Jianfu Zhao
  • Technical Paper
  • 2020-01-1137
To be published on 2020-04-14 by SAE International in United States
Homogeneous charge compression ignition (HCCI) combined with high compression ratio is an effective way to improve engines’ thermal efficiency. However, the severe thermodynamic conditions at high load may induce knocking combustion thus damage the engine body. In this study, advanced compression ignition knocking characteristics were parametrically investigated through RCM experiments and simulation analysis. First, the knocking characteristics were optically investigated. The experimental results show that there even exists detonation when the knock occurs thus the combustion chamber is damaged. Considering both safety and costs, the effects of different initial conditions were numerically investigated and the results show that knocking characteristics is more related to initial pressure other than initial temperature. The initial pressure has a great influence on peak pressure and knock intensity while the initial temperature on knock onset. Further analysis shows that knock intensity is mainly related to the energy density of the in-cylinder mixture and energy density is higher under higher pressure conditions. Then the effects of different cylinder wall temperature on the local autoignition thus knocking characteristics were further discussed. The…
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Analytical Approach to Characterize the Effect of Engine Control Parameters and Fuel Properties on ACI Operation in a GDI Engine

Argonne National Laboratory-Johannes Rohwer, Ashish Shah, Toby Rockstroh
  • Technical Paper
  • 2020-01-1141
To be published on 2020-04-14 by SAE International in United States
Advanced compression ignition (ACI) operation in gasoline direct injection (GDI) engines is a promising concept to reduce fuel consumption and emissions at part load conditions. However, combustion phasing control and the limited operating range in ACI mode are a perennial challenge. In this study the combined impact of fuel properties and engine control strategies in ACI operation are investigated. A design of experiments method was implemented using a three level orthogonal array to determine the sensitivity of engine control parameters on the engine load, combustion noise and stability under low load ACI operation for three RON 98 gasoline fuels, each exhibiting disparate chemical composition. Furthermore, the thermodynamic state of the compression histories was studied with the aid of the pressure-temperature framework. Due to the compression ratio constraints imposed by knock limited SI operation, considerable intake temperature heating was required and ACI operation resulted in the intermediate to high temperature autoignition regime. The olefin containing fuel was found to be most sensitive to intake air heating, thereby enhancing its potential suitability for ACI operation, while still…
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KNOCK Detection with Series Cylinder Pressure Sensors

Technical University of Munich-Matthias Gaderer
Vitesco Technologies GmbH-Harry Schuele, Johannes Beer
  • Technical Paper
  • 2020-01-1143
To be published on 2020-04-14 by SAE International in United States
Current legal requirements based on new driving cycles like WLTP or RDE focus on elevated power and torque from the engine. The gear ratios are chosen so as to permit low engine speeds to reduce fuel consumption and consequently CO2 emissions by shifting the operating point to higher loads with reduced throttling and friction losses at low engine speeds. To achieve the required acceleration values the engine tends to be operated more frequently close to its power and torque limits. Thus, the knock occurring at the load limits will increase in significance. Today, in series production, knock is detected via structure-borne sound sensors and eliminated via retarded ignition. New low-cost in-cylinder pressure sensors (ICPS) suitable for series-production now permit evaluation of every single combustion cycle, thus detecting knock in the engine control unit (ECU) at all speed and load ratios independent of parasitic noise. This paper presents the potential for knock detection and knock control using series-production capable cylinder pressure sensors. First, the basic differences of the algorithm of a structure-borne sensor and a cylinder…
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Potential Analysis and Virtual Development of SI Engines Operated with Synthetic Fuel DMC+

FKFS-Cornelius Wagner, Michael Grill, Mahir-Tim Keskin
FKFS / University of Stuttgart-Michael Bargende
  • Technical Paper
  • 2020-01-0342
To be published on 2020-04-14 by SAE International in United States
On the way to emission-free mobility, future fuels must be CO2 neutral. To achieve this, synthetic fuels are being developed. In order to better assess the effects of the new fuels on the engine process, simulation models are being developed that reproduce the chemical and physical properties of these fuels.In this paper, the fuel DMC+ is examined. DMC+ (a mixture of dimethyl carbonate (DMC) and methyl formate (MeFo) mainly, characterized by the lack of C-C Bonds and high oxygen content) offers advantages with regard to evaporation heat, demand of oxygen and knock resistance. Furthermore, its combustion is almost particle free. With the aid of modern 0D/1D simulation methods, an assessment of the potential of DMC+ can be made.It is shown that the simulative conversion of a state-of-the-art gasoline engine to DMC+ fuel offers advantages in terms of efficiency in many operating points even if the engine design is not altered. This is mainly due to the higher knock resistance and the lower temperatures in the intake stroke resulting from the higher amount of evaporated fuel.…
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Simulation-Based Evaluation of Spark-Assisted Compression Ignition Control for Production

Clemson University-Dennis Robertson, Robert Prucka
  • Technical Paper
  • 2020-01-1145
To be published on 2020-04-14 by SAE International in United States
Spark-assisted compression ignition (SACI) leverages flame propagation to trigger autoignition in a controlled manner. The autoignition event is highly sensitive to several parameters, and thus, achieving SACI in production demands a high tolerance to variations in conditions. Limited research is available to quantify the combustion response of SACI to these variations. A simulation study is performed to establish trends, limits, and control implications for SACI combustion over a wide range of conditions. The operating space was evaluated with a detailed chemical kinetics model. Key findings were synthesized from these results and applied to a 1-D engine model. This model identified performance characteristics and potential actuator positions for a production-viable SACI engine. This study shows charge preparation is critical and can extend the low-load limit by strengthening flame propagation and the high-load limit by reducing ringing intensity. The simulation results also suggest that under certain operating conditions, there can be a significant disparity between the autoignition sensitivity to temperature and pressure. This may dictate different load control or combustion phasing control strategies, and these results are…