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The Effect of EGR Dilution on the Heat Release Rates of Boosted Spark-Assisted Compression Ignition (SACI) Engines

Robert Bosch LLC-Jeff Sterniak
University of Delaware-Dennis Assanis
  • Technical Paper
  • 2020-01-1134
To be published on 2020-04-14 by SAE International in United States
This paper presents an experimental investigation of the impact of EGR dilution on the tradeoff between flame and end-gas autoignition heat release in a Spark-Assisted Compression Ignition (SACI) combustion engine. The mixture was maintained stoichiometric and fuel-to-charge equivalence ratio (ϕ') was controlled by varying the EGR dilution level at constant engine speed. Under all conditions investigated, end-gas autoignition timing was maintained constant by modulating the mixture temperature and spark timing. Experiments at constant intake pressure and spark timing showed that as ϕ' is increased, lower mixture temperatures are needed to match end-gas autoignition timing. Higher ϕ' mixtures exhibited faster initial flame burn rates, which were attributed to the higher estimated laminar flame speeds immediately after spark timing. At constant intake pressure and mass fraction burned at the onset of autoignition, end-gas autoignition rates increased significantly at higher ϕ' conditions. The increasing trends in peak autoignition rate and end-gas energy at autoignition onset were found to be consistent for all intake pressures ranging from 80 kPa to 150 kPa. For a constant spark timing, the mass…
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A Decentralized Time- and Energy-Optimal Control Framework for Connected Automated Vehicles: From Simulation to Field Test

Robert Bosch LLC-Vasanthi Karri, Darshil Parikh, Shyam Jade
University Of Delaware-A M Ishtiaque Mahbub, Andreas A. Malikopoulos
  • Technical Paper
  • 2020-01-0579
To be published on 2020-04-14 by SAE International in United States
The implementation of connected and automated vehicle (CAV) technologies enables a novel computational framework for real-time control aimed at optimizing energy consumption with associated benefits. In this paper, we implement an optimal control framework, developed previously, in an Audi A3 etron plug-in hybrid electric vehicle, and demonstrate that we can improve the vehicle’s efficiency and travel time in a corridor including an on-ramp merging, a speed reduction zone, and a roundabout. Our exposition includes the development, integration, implementation and validation of the proposed framework in (1) simulation, (2) hardware-in-the-loop (HIL) testing, (3) connectivity enabled virtual reality based bench-test, and (4) field test in Mcity. We show that by adopting such inexpensive, yet effective process, we can efficiently integrate and test the control framework, establish proper connectivity and data transmission between different modules of the system, and reduce uncertainty. We evaluate the performance and effectiveness of the control framework and observe significant improvement in terms of energy and travel time compared to the baseline scenario.
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Use of Active Rear Steering to Achieve Desired Vehicle Transient Lateral Dynamics

Robert Bosch LLC-Lance Bredthauer
General Motors LLC-David Lynch
Published 2018-04-03 by SAE International in United States
This paper studies the use of active rear steering (4-wheel steering) to change the transient lateral dynamics and body motion of passenger cars in the stable or linear region of the tires. Rear steering systems have been used for several decades to improve low speed turning maneuverability and high speed stability, and various control strategies have been previously published. With a model-based, feed-forward rear steer control strategy, the lateral transient can be influenced separately from the steady-state steering gain. This lateral transient is influenced by many vehicle parameters, but we will look at the influence of active rear steer and various tire types such as all-season, snow, and summer. This study will explore the ability for a rear steering system to change the lateral transient to a step steer input, compared to the effect of changing tire types. While the yaw rate response to a steering input can be dramatically influenced by rear steering, the effect in a dynamic maneuver can feel very unnatural and unpleasant to a human driver. This paper also seeks to…
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Effects of Engine Speed on Spray Behaviors of the Engine Combustion Network “Spray G” Gasoline Injector

Robert Bosch LLC-Mohammad Fatouraie
University of Melbourne-Joshua Lacey, Michael Brear
Published 2018-04-03 by SAE International in United States
Non-reacting spray behaviors of the Engine Combustion Network “Spray G” gasoline fuel injector were investigated at flash and non-flash boiling conditions in an optically accessible single cylinder engine and a constant volume spray chamber. High-speed Mie-scattering imaging was used to determine transient liquid-phase spray penetration distances and observe general spray behaviors. The standardized “G2” and “G3” test conditions recommended by the Engine Combustion Network were matched in this work and the fuel was pure iso-octane. Results from the constant volume chamber represented the zero (stationary piston) engine speed condition and single cylinder engine speeds ranged from 300 to 2,000 RPM. As expected, the present results indicated the general spray behaviors differed significantly between the spray chamber and engine. The differences must be thoughtfully considered when applying spray chamber results to guide spray model development for engine applications. Overall, increases in engine speed correlated well with enhanced vaporization, loss of distinct plume structure, and enhanced spray collapse which led to reductions in wetted-footprint area. Furthermore, while loss of distinct plume structures appeared to be strongly dependent…
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Investigation of the Impact of Fuel Properties on Particulate Number Emission of a Modern Gasoline Direct Injection Engine

Robert Bosch LLC-Mohammad Fatouraie, Mario Frommherz, Michael Mosburger
General Motors LLC-Elana Chapman, Sharon Li
Published 2018-04-03 by SAE International in United States
Gasoline Direct Injection (GDI) has become the preferred technology for spark-ignition engines resulting in greater specific power output and lower fuel consumption, and consequently reduction in CO2 emission. However, GDI engines face a substantial challenge in meeting new and future emission limits, especially the stringent particle number (PN) emissions recently introduced in Europe and China. Studies have shown that the fuel used by a vehicle has a significant impact on engine out emissions. In this study, nine fuels with varying chemical composition and physical properties were tested on a modern turbo-charged side-mounted GDI engine with design changes to reduce particulate emissions. The fuels tested included four fuels meeting US certification requirements; two fuels meeting European certification requirements; and one fuel meeting China 6 certification requirements being proposed at the time of this work. Two risk safeguard fuels (RSG), representing the properties of worst case market fuels in Europe and China, were also included. The particle number concentration of the solid particulates was measured in the engine-out exhaust flow at steady state engine operations with load…
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High-Speed Imaging Studies of Gasoline Fuel Sprays at Fuel Injection Pressures from 300 to 1500 bar

Robert Bosch LLC-Mohammad Fatouraie
University of Michigan-Mario Medina, Margaret Wooldridge
Published 2018-04-03 by SAE International in United States
High-pressure gasoline fuel injection is a means to improve combustion efficiency and lower engine-out emissions. The objective of this study was to quantify the effects of fuel injection pressure on transient gasoline fuel spray development for a wide range of injection pressures, including over 1000 bar, using a constant volume chamber and high-speed imaging. Reference grade gasoline was injected at fuel pressures of 300, 600, 900, 1200, and 1500 bar into the chamber, which was pressurized with nitrogen at 1, 5, 10, and 20 bar at room temperature (298 K). Bulk spray imaging data were used to quantify spray tip penetration distance, rate of spray tip penetration and spray cone angle. Near-nozzle data were used to evaluate the early spray development.The bulk characteristics of the high pressure gasoline sprays were consistent with trends previously observed at lower fuel injection pressures, e.g. spray tip penetration distance increased with increased fuel injection pressure after the spray break-up time and sprays with higher cone angles were produced with increasing chamber pressure at constant fuel injection pressure. The spray break-up time was a…
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A Model Based Approach for Generating Pre-Calibration Data for Two-Wheelers

Robert Bosch LLC-Srikanth Vijaykumar
Bosch Limited-Balagovind Nandakumar Kartha, Pramod Reddemreddy
  • Technical Paper
  • 2017-32-0038
Published 2017-11-05 by Society of Automotive Engineers of Japan in Japan
Today, 99% of the two wheelers in India operate with carburetor based fuel delivery system. But with implementation of Bharath Stage VI emission norms, compliance to emission limits along with monitoring of components in the system that contributes towards tail pipe emissions would be challenging. With the introduction of the OBD II (On-Board Diagnostics) and emission durability, mass migration to electronically controlled fuel delivery system is very much expected. The new emission norms also call for precise metering of the injected fuel and therefore demands extended calibration effort.The calibration of engine management system starts with the generation of pre-calibration dataset capable of operating the engine at all operating points followed by base calibration of the main parameters such as air charge estimation, fuel injection quantity, injection timing and ignition angles relative to the piston position. Finally, the vehicle calibration is executed keeping drivability and compliance to legislative norms as prime requirements. The quality of the pre-calibration data and base calibration decides the number of iterations required to arrive at the final dataset that meets the…
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Diagnosing Sources of Automotive System Radio Frequency Interference (RFI) Using a Portable RF Detector Instrument

Robert Bosch LLC-Cyrous Rostamzadeh
GM Global Propulsion Systems-Mark Steffka
Published 2016-04-05 by SAE International in United States
Automotive systems can generate un-intentional radio frequency energy. The levels of these emissions must be below maximum values set by the Original Equipment Manufacturer (OEM) for customer satisfaction and/or in order to meet governmental requirements. Due to the complexity of electromagnetic coupling mechanisms that can occur on a vehicle, many times it is difficult to measure and identify the noise source(s) without the use of an electromagnetic interference (EMI) receiver or spectrum analyzer (SA). An efficient and effective diagnostic solution can be to use a low-cost portable, battery powered RF detector with wide dynamic range as an alternative for automotive electromagnetic compatibility (EMC) and design engineers to identify, locate, and resolve radio frequency (RF) noise problems. A practical circuit described here can be implemented easily with little RF design knowledge, or experience. Functional diagram and electrical circuit schematic details are illustrated and explained. A few possible EMI scenarios are examined and investigated with the use of a portable RF detector and results are compared to an EMI receiver, showing that this method can be and…
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A Control Algorithm for Low Pressure - EGR Systems Using a Smith Predictor with Intake Oxygen Sensor Feedback

Robert Bosch LLC-Shyam Jade, Jason Schwanke
Clemson University-Rohit Koli, Konstantinos Siokos, Robert Prucka
Published 2016-04-05 by SAE International in United States
Low-pressure cooled EGR (LP-cEGR) systems can provide significant improvements in spark-ignition engine efficiency and knock resistance. However, open-loop control of these systems is challenging due to low pressure differentials and the presence of pulsating flow at the EGR valve. This research describes a control structure for Low-pressure cooled EGR systems using closed loop feedback control along with internal model control. A Smith Predictor based PID controller is utilized in combination with an intake oxygen sensor for feedback control of EGR fraction. Gas transport delays are considered as dead-time delays and a Smith Predictor is one of the conventional methods to address stability concerns of such systems. However, this approach requires a plant model of the air-path from the EGR valve to the sensor. An open loop EGR mass flow model as well as a simplified plug flow based transport model are utilized to predict EGR fraction at different locations in the air system upstream of the intake oxygen sensor. A turbocharged gasoline spark ignition engine with a low-pressure EGR system is used for algorithm validation.…
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Physics-Based Exhaust Pressure and Temperature Estimation for Low Pressure EGR Control in Turbocharged Gasoline Engines

Robert Bosch LLC-Jason Schwanke, Shyam Jade
Clemson University-Konstantinos Siokos, Rohit Koli, Robert Prucka
Published 2016-04-05 by SAE International in United States
Low pressure (LP) and cooled EGR systems are capable of increasing fuel efficiency of turbocharged gasoline engines, however they introduce control challenges. Accurate exhaust pressure modeling is of particular importance for real-time feedforward control of these EGR systems since they operate under low pressure differentials. To provide a solution that does not depend on physical sensors in the exhaust and also does not require extensive calibration, a coupled temperature and pressure physics-based model is proposed. The exhaust pipe is split into two different lumped sections based on flow conditions in order to calculate turbine-outlet pressure, which is the driving force for LP-EGR. The temperature model uses the turbine-outlet temperature as an input, which is known through existing engine control models, to determine heat transfer losses through the exhaust. Temperature output is used in the pressure model to estimate pressure losses in the two sections of the pipe starting from post-catalyst (ambient) conditions. Experimental data is used to calibrate a total of six parameters in the pressure and steady-state temperature models. Transient experiments are utilized to…
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