Browse Topic: Variable valve timing

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Test 123SAE-PP-005182/8/2022
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Basile, Julia, Mutagaana, Festo
Continuously Variable Displacement Drive for Engines Part 2, Design, Analysis, and TestSAE-PP-005162/8/2022
A new type of drive system has been designed, analyzed, patented, prototyped, and tested. The drive’s unique capabilities include the ability to vary the bottom dead center position to reduce the stroke, and simultaneously vary the top dead center position to achieve the desired compression ratio with one simple, low friction mechanism. The purpose of the concept is to reduce losses associated with operation at partial load as most engines spend a preponderance of their operating life at partial load. This paper covers the design and analysis, prototyping, and testing of the unit as an air compressor. Engine simulation of the unit configured as a gasoline engine showed a ~30% improvement in fuel economy on a 10-mode weighted cycle and is covered in SAE 2021-01-0442, “Continuously Variable Displacement Drive for Engines Part 1, Performance Simulation.”
Basile, Julia
Generating some more TasksSAE-PP-0049311/10/2021
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Kelly, Jason
7.0.112 - Design and Development of Variable Valve Actuation (VVA) Mechanism Concept for Multi-Cylinder EngineSAE-PP-002882/4/2021
The desire for higher fuel economy, improved performance and driveability expectations of customers from engines are gradually increasing along with stringent emission regulations set by the government. Many original engine manufacturing companies are prompted to consider the application of higher function variable valve actuation mechanisms in their next generation vehicles as a solution. The VVA is a generalized term used to describe any mechanism or method that can alter the shape or timing of a valve lift event within an internal combustion engine. The VVA allows lift, duration or timing (in various combinations) of the intake and/or exhaust valves to be changed while the engine is in operation. Engine designers are prompted to consider Variable Valve Actuation (VVA) system because of the inherent compromises with fixed valve events. The major goal of a VVA engine is to control the amount of air inducted into the engine which is a direct measure of torque. This work presents a novel two-step VVA mechanism to facilitate variation in valve timing and lift of base engine. The mechanism helps the engine breathe effectively by changing the valve timing and lift after the set switch-over point engine speed, by dividing the operating range of engine into two zones viz, low speed and high speed zone.
Downsized-Boosted Gasoline Engine with Exhaust Compound and Dilute Advanced Combustion2020-01-07954/14/2020
This article presents experimental results obtained with a disruptive engine platform, designed to maximize the engine efficiency through a synergetic implementation of downsizing, high compression-ratio, and importantly exhaust-heat energy recovery in conjunction with advanced lean/dilute low-temperature type combustion. The engine architecture is a supercharged high-power output, 1.1-liter engine with two-firing cylinders and a high compression ratio of 13.5: 1. The integrated exhaust heat recovery system is an additional, larger displacement, non-fueled cylinder into which the exhaust gas from the two firing cylinders is alternately transferred to be further expanded. The main goal of this work is to implement in this engine, advanced lean/dilute low-temperature combustion for low-NOx and high efficiency operation, and to address the transition between the different operating modes. Those include well-mixed charge compression-ignition at low-load, and a mixed-mode combustion at higher loads, before transitioning to boosted homogenous and stochiometric spark-ignited combustion. Here, the mixed-mode combustion strategy is composed of a deflagration of a stratified mixture created by a late direct injection, then triggering a controlled autoignition of the surrounding gas, improving the robustness of lean/dilute combustion. The paper describes the key features of the engine and details regarding the combustion and multi-mode valve strategies. The experiments were performed under steady-state operation at 2000 rpm, from 1 to 11 bar IMEPn and naturally aspirated conditions. The engine demonstrated great efficiency gains compared to a conventional naturally-aspirated and downsized-boosted spark-ignited engines. The piston-compounding exhaust-heat recovery system contributes to up to 10% of the total efficiency improvement, while lean/dilute advanced combustion increases the fuel economy by up to 38% compared to a naturally aspirated engine, and up to 22%, compared to a downsized-boosted engine. NOx emissions target was met using high-levels of internal and external dilution in mixed-mode combustion operation, as well as by optimizing the injection and ignition strategy. Finally, the analysis shows that a seamless transition between the different valving strategies is achievable in support of robust transient operation.
Dernotte, Jeremie, Najt, Paul M., Durrett, Russell P.
The Use of Piezoelectric Washers for Feedback Combustion Control2020-01-11464/14/2020
The use of piezoelectric cylinder pressure sensors is very popular during engine testing, but cylinder pressure information is becoming mandatory also in several on-board applications, where Low Temperature Combustion (LTC) approaches require a feedback control of combustion, due to poor combustion stability and the risk of knock or misfire. Several manufacturers showed the capability to develop solutions for cylinder pressure sensing in on-board automotive and aeronautical applications, and some of them have been patented. The most straight-forward approach seems the application of a piezo-electric washer as a replacement of the original part equipping the spark plug; the injector could also be used to transfer the cylinder pressure information to the piezoelectric quartz, in diesel or Gasoline Direct Injections (GDI) engines. The paper describes the features of signals acquired using piezoelectric washers, discussing possible applications, highlighting the factors which impact the sensors accuracy, and proposing algorithms to compensate potential errors in the evaluation of combustion metrics. The sensors have been first tested on a press, then in two different gasoline engines: a naturally aspirated V12 and a turbocharged 2 cylinders with Variable Valve Lift system (VVL). Signals have been compared to those obtained with lab-grade cylinder pressure sensors, with particular attention to peak pressure, combustion phase and knock intensity. The main issue affecting the accuracy of cylinder pressure measurement using the piezoelectric spark plug washer is the effect of temperature variations both on the force transmitted by the thread to the washer and piezoelectricity properties.
Corti, Enrico, Abbondanza, Marco, Ponti, Fabrizio, Raggini, Lorenzo
Initial Investigations into the Benefits and Challenges of Eliminating Port Overlap in Wankel Rotary Engines2020-01-02804/14/2020
The Wankel rotary engine historically found limited success in automotive applications due in part to poor combustion efficiency and challenges around emissions. This is despite its significant advantages in terms of power density, compactness, vibrationless operation, and reduced parts count in relation to the 4-stroke reciprocating engine, which is now-dominant in the automotive market. A large part of the reason for the poor fuel economy and high hydrocarbon emissions of the Wankel engine is that there is a very significant amount of overlap when the ports are opened and/or closed by the rotor apices (so-called peripheral ports). This paper investigates the benefits of zero overlap from a production engine with this characteristic and the effect of configuring a peripherally-ported Wankel engine in such a manner. As discussed in the paper, arranging this condition for peripherally-ported engines unfortunately reduces the trapped compression and/or expansion ratios significantly, such that when naturally-aspirated operation is simulated, a large reduction in performance ensues. In order to demonstrate the potential of zero port overlap in Wankel engines with respect to emissions, a 2007 model year Mazda RX-8 was rebuilt, run-in, degreened, and tested on a chassis dynamometer. As standard, the engine in this vehicle is configured with no port overlap through the adoption of side intake and exhaust ports. This testing was performed in order to see subjectively how successful such an approach could be in controlling emissions. The vehicle easily met Euro 5 limits for all criteria emissions and was even better in terms of hydrocarbon emissions versus Euro 6 on the WLTP cycle, giving the lie to the belief that a Wankel engine can no longer meet current automotive emissions targets. The analytical work reported here studies the result of eliminating overlap on the performance of a peripherally-ported single-rotor Wankel engine using a 1-D model. This was implemented and correlated to the in-production Advanced Innovative Engineering (UK) Ltd 225CS engine used in the UK government-funded ADAPT project. The initial port study focused on advancing and retarding the exhaust and intake port respectively to achieve zero port overlap and then sweeping their zero-overlap positions together around the trochoid housing. The best location for the ports was then identified; this was essentially an “Otto” timing set, with broadly equal compression and expansion ratios. Notwithstanding this, potential performance was found to be severely curtailed, as was to be expected given the marked reduction in trapped compression and/or expansion ratios necessary due to peripheral porting. Countermeasures to this reduction are discussed. Those that will be studied later in the project will be reported in a later publication.
Turner, James, Turner, Matthew, Vorraro, Giovanni, Thomas, Toby
Prediction of Fuel Maps in Variable Valve Timing Spark Ignited Gasoline Engines Using Kriging Metamodels2020-01-07444/14/2020
Creating a fuel map for simulation of an engine with Variable Valve Actuation (VVA) can be computationally demanding. Design of Experiments (DOE) and metamodeling is one way to address this issue. In this paper, we introduce a sequential process to generate an engine fuel map using Kriging metamodels which account for different engine characteristics such as load and fuel consumption at different operating conditions. The generated map predicts engine output parameters such as fuel rate and load. We first create metamodels to accurately predict the Brake Mean Effective Pressure (BMEP), fuel rate, Residual Gas Fraction (RGF) and CA50 (Crank Angle for 50% Heat Release after top dead center). The last two quantities are used to ensure acceptable combustion. The metamodels are created sequentially to ensure acceptable accuracy is achieved with a small number of simulations. Two optimization problems are then solved using the developed metamodels, for full load and part load conditions, respectively. We demonstrate that the estimated fuel map is of high accuracy compared to the actual map. The map is obtained with about one tenth of the number of engine simulations for a full factorial design, leading to much faster predictions.
Tafreshi, Ali, Mourelatos, Zissimos
Effect of a Cylinder Deactivation Actuator with Electro-Mechanical Switching System on Fuel Economy of an Automotive Engine2020-01-14084/14/2020
This paper introduces a two-step CDA mechanism equipped with an electro-mechanical switching system, which can be applied to OHC valve trains with end pivot rocker arms, and can operate two valves simultaneously with a single cam. The electro-mechanical switching system is driven by a dedicated solenoid, so the latching and unlatching processes are not affected by the temperature and pressure of the engine oil. Therefore, not only the dynamic stability can be secured at the time of mode switching but also the operation delay time can be kept short enough. To verify the effect of the CDA system on the fuel economy, a four-cylinder 2.0L gasoline engine with the intake port injection was selected and tested on an engine dynamometer. The effect of the present apparatus was evaluated by measuring the fuel economy of the engine in the two test modes: Federal Test Procedure-75 (FTP-75) and Worldwide Harmonized Light Vehicles Test Procedure (WLTP). The optimal operating conditions were established which minimize the engine vibration, friction loss and the adverse effects on fuel efficiency. According to the optimum operating conditions, the fuel efficiency improvements of 9.56% and 8.01% were obtained in FTP-75 and WLTP test modes respectively. Stable and quick response of the electro-mechanical switching system may attribute to the relatively big improvements in the fuel economy.
Lee, Dong Hyeong, Kim, Dojoong, Jeon, Wan Jae, Hong, Yong Seok, Park, Jong Wung
A Real-Time Capable and Modular Modeling Concept for Virtual SI Engine Development2020-01-05774/14/2020
Spark Ignited (SI) combustions engines in combination with different degrees of hybridization are expected to play a major role in future vehicle propulsion. Due to the combustion principle and the related thermodynamic efficiency, it is especially challenging to meet future CO2 targets. The layout and optimization of the overall system requires novel methods in the development process which feature a seamless transition between real and virtual prototypes. Herein, engine models need to predict the entire engine operating range in steady-state and transient conditions and must respond to all relevant control inputs. In addition, the model must feature true real-time capability. This work presents a holistic and modular modeling framework, which considers all relevant processes in the complex chain of physical effects in SI combustion. The basis is a crank-resolved cylinder model which describes gas exchange and compression to determine the thermodynamic state and turbulence conditions at spark-advance. Ignition and flame front combustion are modeled by a mechanistic, quasi-dimensional combustion model with a detailed consideration of combustion chamber geometry for flame-wall interaction. Cycle-to-cycle variations are imposed in a semi-empirical manner in order to provide realistic boundary conditions for the thermo-chemical knock model. The models are validated against engine measurements for a passenger car sized TGDI engine in a wide range of operating conditions covering the entire engine map. Emphasis is put on comparing pressure and heat release traces, not only for the mean cycle, but for the range of stochastic variations of 100 measured cycles. The validation results confirm a good level of agreement between measured and simulated results. To demonstrate capabilities of the proposed modeling concept, a model-based optimization is performed in a computational study, aiming at an optimization of engine efficiency under knocking constraints. The study examines two motoric measures, namely water injection and variable compression ratio. Finally, the optimized model runs in a transient drivecycle simulation. The test is performed on a HiL system to prove the model’s real-time capability.
Poetsch, Christoph, Wurzenberger, Johann, Katrasnik, Tomaz
Experimental and 1D Numerical Investigations on the Exhaust Emissions of a Small Spark Ignition Engine Considering the Cylinder-by-Cylinder Variability2020-01-05784/14/2020
This paper reports a numerical and experimental analysis on a twin-cylinder turbocharged Spark Ignition engine carried out to investigate the cylinder-to-cylinder variability in terms of performance, combustion evolution and exhaust emissions. The engine was tested at 3000 rpm in 20 different steady-state operating conditions, selected with the purpose of observing the influence of cylinder-by-cylinder A/F ratio variations and the EGR effects on the combustion process and exhaust emissions for low to medium/high loads. The experimental outcomes showed relevant differences in the combustion evolution (characteristic combustion angles) between cylinders and not negligible variations in the emissions of the single cylinder exhaust and the overall engine one. This misalignment resulted to be due to differences in the injected fuel amount by the port injectors in the two cylinders, mainly deriving from the specific fuel rail geometry. The experimental data were then used to validate a 1D engine model, integrated with refined sub-models of turbulence, combustion, heat transfer and emissions. The model takes into account the in-cylinder production of noxious species, and their propagation in the exhaust system, up to the three-way catalytic converter. A satisfactory accuracy was reached in reproducing the overall engine performance and the combustion process in the two cylinders. In particular, the emission sub-models confirmed that the variations of the cylinder-out exhaust emissions (NOx, HC and CO) were mainly due to the non-uniform effective in-cylinder A/F ratio. The proposed numerical methodology has the potential to highlight unexpected combustion non-uniformities among different cylinders and represents a powerful support to the engine design and development. It also allows for the prediction of the overall exhaust emissions at different engine operating conditions up to the entire domain, thus assisting the engine calibration phase and reducing the experimental efforts.
Marchitto, Luca, Teodosio, Luigi, Tornatore, Cinzia, Valentino, Gerardo, Bozza, Fabio
Discharge Current Management for Diluted Combustion under Forced Flow Conditions2020-01-11184/14/2020
Lean burn or EGR diluted combustion with enhanced charge motion is effective in improving the efficiency of spark ignition engines. However, the ignition process under these conditions is getting more challenging due to higher ignition energy required by the lean or diluted mixture, as well as the interactions of the gas flow on the flame kernel. Enhanced spark discharge energy is essential to initiate the combustion under these conditions. Moreover, the discharge process should be more carefully controlled to improve the effectiveness of the spark. In this study, spark ignition systems with boosted discharge energy are used to ignite diluted air-fuel mixture under forced flow conditions. The impacts of the discharge current level, the discharge duration and the discharge current profile on the ignition are investigated in detail using optical diagnosis. It is evident from the results that extended discharge duration helps promote the flame propagation, though the effectiveness is limited when the duration exceeds the required minimum value for a self-sustained flame kernel. A higher discharge current level is favorable for generating a stronger flame kernel. With similar discharge energy delivered to the spark gap, a high-current spark with a shorter duration performs better than a longer duration low-current spark. Then the impacts of discharge current profiles are studied. Three spark discharge strategies, including a low-current continuous discharge, a high-current multi-pulse discharge, and a very high transient current discharge, are used in the comparison. The results reveal that sufficiently long discharge duration is critical for success ignition under the tested flow condition. Among the three ignition strategies, the low-current continuous spark discharge performs the best, even with the lowest discharge energy, due mainly to the continuous nature of the spark discharge.
Yang, Zhenyi, Wang, Linyan, Sandhu, Navjot S., Yu, Xiao, Zheng, Ming
Application of the Passive MAHLE Jet Ignition System and Synergies with Miller Cycle and Exhaust Gas Recirculation2020-01-02834/14/2020
Driven by legislation, economics and increasing societal awareness, engine and vehicle manufacturers are facing increasing pressure to reduce vehicle emissions and deliver improved fuel economy. Significant reductions in carbon dioxide (CO2) emissions will need to be achieved to meet these requirements whilst at the same time satisfying the more stringent forthcoming emissions regulations. This focus on techniques to reduce the tailpipe CO2 is increasing the interest in novel combustion technologies, including dilute combustion in gasoline engines. The pre-chamber based jet ignition concept produces high energy jets of partially combusted species that induce ignition at multiple locations in the main combustion chamber to enable rapid, stable combustion, even with dilute mixtures. The present study focusses on the beneficial synergies of the pre-chamber system with high geometric compression ratio (CR), Miller cycle operation and cooled external exhaust gas recirculation (EGR). The study has been undertaken using the MAHLE 1.5 liter, 3-cylinder, downsized demonstrator engine. The interaction of the various technologies applied to the engine, will be discussed and the improvements in fuel consumption due to the technology package that has been applied relative to the baseline engine will be presented. A critical challenge for pre-chamber based combustion systems is achieving operation over a wide operating region and under low load and cold start conditions. Results from the study demonstrating the capability of the pre-chamber concept to enable whole map operation as well as idle stability, catalyst light-off capability to a conventional central spark plug will also be presented.
Cooper, Adrian, Harrington, Anthony, Bassett, Michael, Reader, Simon, Bunce, Michael
Combustion System Optimization of a Light-Duty GCI Engine Using CFD and Machine Learning2020-01-13134/14/2020
In this study, the combustion system of a light-duty compression ignition engine running on a market gasoline fuel with Research Octane Number (RON) of 91 was optimized using computational fluid dynamics (CFD) and Machine Learning (ML). This work was focused on optimizing the piston bowl geometry at two compression ratios (CR) (17 and 18:1) and this exercise was carried out at full-load conditions (20 bar indicated mean effective pressure, IMEP). First, a limited manual piston design optimization was performed for CR 17:1, where a couple of pistons were designed and tested. Thereafter, a CFD design of experiments (DoE) optimization was performed where CAESES, a commercial software tool, was used to automatically perturb key bowl design parameters and CONVERGE software was utilized to perform the CFD simulations. At each compression ratio, 128 piston bowl designs were evaluated. Subsequently, a Machine Learning-Grid Gradient Algorithm (ML-GGA) approach was developed to further optimize the piston bowl design. This extensive optimization exercise yielded significant improvements in the engine performance and emissions compared to the baseline piston bowl designs. Up to 15% savings in indicated specific fuel consumption (ISFC) were obtained. Similarly, the optimized piston bowl geometries produced significantly lower emissions compared to the baseline. Emissions reductions up to 90% were obtained from this optimization exercise. The performances of the optimized piston bowl geometries were further validated at different operating conditions at the high-load point and at part-load conditions (6 bar IMEP) and compared with those of the baseline designs. The dependence of the engine performance on the piston bowl geometry at part-loads was lower than that at high-loads because injections normally occurred earlier (-60 to -20 CAD after top dead center (aTDC)) where minimal interactions between the spray and piston were anticipated. The interactions between late injections (-3 to 3 CAD aTDC) and piston geometry at high-loads significantly affected, fuel-air mixing, droplet breakup, combustion and emissions. It was also observed that heat losses, dictated by the interactions between the flame and piston surface, significantly affected the performance of the engine.
Badra, Jihad, khaled, Fethi, Sim, Jaeheon, Pei, Yuanjiang, Viollet, Yoann, Pal, Pinaki, Futterer, Carsten, Brenner, Mattia, Som, Sibendu, Farooq, Aamir, Chang, Junseok
The Effect of Heavy-Duty Diesel Cylinder Deactivation on Exhaust Temperature, Fuel Consumption, and Turbocharger Performance up to 3 bar BMEP2020-01-14074/14/2020
Diesel Cylinder Deactivation (CDA) has been shown in previous work to increase exhaust temperatures, improve fuel efficiency, and reduce engine-out NOx for engine loads up to 3 bar BMEP. The purpose of this study is to determine whether or not the turbocharger needs to be altered when implementing CDA on a diesel engine. This study investigates the effect of CDA on exhaust temperature, fuel efficiency, and turbocharger performance in a 15L heavy-duty diesel engine under low-load (0-3 bar BMEP) steady-state operating conditions. Two calibration strategies were evaluated. First, a “stay-hot” thermal management strategy in which CDA was used to increase exhaust temperature and reduce fuel consumption. Next, a “get-hot” strategy where CDA and elevated idle speed was used to increase exhaust temperature and exhaust enthalpy for rapid aftertreatment warm-up. The “stay-hot” CDA strategy demonstrated increased exhaust temperatures up to 200°C while simultaneously reducing fuel consumption by 5-40% depending on the operating condition. The “get hot” CDA strategy demonstrated up to 200°C increases in exhaust temperature in addition to 10kW increase in exhaust enthalpy over baseline operation. The effect of CDA on the turbocharger performance was noticeable, but only affected a small part of the engine operating map where CDA was active. Overall, turbocharger efficiency decreased with CDA; however, the reduced pumping work from the deactivated cylinders still provided a fuel efficiency benefit. Examining the individual components, the compressor efficiency decreased with CDA due to the reduced engine air flow while the turbine efficiency increased. The study concluded that the same turbocharger as a non-CDA engine should still be selected for diesel CDA engines.
Morris, Andrew, McCarthy, James
Numerical Investigation of Diesel-Spray-Orientated Piston Bowls on Natural Gas and Diesel Dual Fuel Combustion Engine2020-01-03114/14/2020
Low combustion efficiency and high hydrocarbon emissions at low loads are key issues of natural gas and diesel (NG-diesel) dual fuel engines. For better engine performance, two diesel-spray-orientated (DSO) bowls were developed based on the existing diesel injector of a heavy-duty diesel engine with the purpose of placing more combustible natural gas/air mixture around the diesel spray jets. A protrusion-ring was designed at the rim of the piston bowl to enhance the in-cylinder flame propagation. Numerical simulations were conducted for a whole engine cycle at engine speed of 1200 r/min and indicated mean effective pressure (IMEP) of 0.6 MPa. Extended coherent flame model 3 zones (ECFM-3Z) combustion model with built-in soot emissions model was employed. Simulation results of the original piston bowl agreed well with the experimental data, including in-cylinder pressure and heat released rate (HRR), as well as soot and methane emissions. Turbulence kinetic energy, IMEP and methane emissions of the DSO piston geometries were compared with that of the original piston geometry. The results showed that both in-cylinder pressure and heat release rate of both DSO piston geometries increased due to higher turbulence kinetic energy comparing to the original piston geometry while methane emissions significantly decreased. Methane combustion with the DSO piston geometries tended to occur far away from the piston center compared to that with the original piston design at the same crank angle due to the protrusion-ring at the rim of piston bowl. Overall, the methane combustion with the DSO pistons was enhanced in the whole combustion chamber, which led to improved combustion efficiency and lower methane emissions.
Shen, Zhaojie, Wang, Xinyan, Zhao, Hua, Shen, Yitao, Yang, Jianguo
Simulation Analysis of the Scavenging Process of a Uniflow and Loop Scavenging Concept2019-32-05491/24/2020
The two-stroke engine, as a today unconventional concept in automotive applications, has a great potential for a relaunch in the fast-growing market of Plugin Hybrid Electric Vehicle (PHEV) or Range Extender Electric Vehicle (REX) [2, 3, 4, 8, 9]. An efficient scavenging to remove the in-cylinder burnt gases and to fill the cylinder with fresh charge, performed at the same time is one of the major challenges, as losses of fresh air and fuel towards the exhaust line should be avoided when operating a lambda = 1 concept necessary for a 3-way catalyst aftertreatment system. A prior study [1] of different gas exchange designs for two-stroke engines concludes that two possible concepts cover this purpose. In this paper, 3D-CFD simulation is used to compare these two different scavenging concepts, a uniflow and a loop scavenging type with control elements for the gas exchange process. As boundary conditions, it is assumed that both concept types have nearly the same displacement, are used with an external scavenging blower and have a lubrication system like a conventional oil sump similar to a four-stroke engine. Additionally, a high-pressure direct injection fuel system is applied to guarantee oil- and fuel-free air for the scavenging process. To compare these different two-stroke scavenging concepts, this study focuses on the scavenging and compression phase using 3D-CFD simulation in order to evaluate the scavenging characteristics and the in-cylinder charge motion. The goal of this study is to prepare a basis for discussion of the best configuration, which will be designed, built and tested on the engine test-bench.
Sturm, Stefan, Lang, Michael, Schmidt, Stephan
Developing High-Performance Motorcycle Oils2019-32-05051/24/2020
Published motorcycle lubricant research often focuses on developments to meet certain specifications, regulatory requirements, or a combination of the two. Seemingly missing from the literature is research where the primary goal is development of a lubricant that enables maximum torque, power and acceleration from a machine for the purpose of winning races. The present study combines the two areas of research, where a high-performance motorcycle engine oil platform is developed to be used in competition, while simultaneously meeting the necessary regulations and specifications to be useful for commuters and leisure riders alike. Well-known are the demands on a motorcycle oil, which must lubricate and protect the crankcase, clutch and gears, all of which have competing requirements such that a strategy to improve the performance in one area can cause a detriment in another. Formulating for racing engines that are typically much more powerful than production versions further exacerbates these dichotomies, where the traditional strategies for gaining power through the lubricant of reducing viscosity or adding friction-reducing chemistries can leave the clutch and gears open to severe damage. To meet these competing demands, a novel additive system with unique anti-wear and friction modifier chemistries was introduced to ensure clutch and gear protection while simultaneously improving power output and minimizing deleterious effects to aftertreatment devices. Further, the oils were designed to withstand the higher temperatures, speeds and power densities found in high performance machines through improved antioxidants, base stocks and shear-stable polymers, which also provide durability across the oil drain interval for leisure riders and commuters alike. Through a combination of performance bench testing, engine dynamometer testing and field testing on the track, it was demonstrated that substantial power gains can be achieved while still maintaining hardware protection, thus achieving the goal of a high-performance racing oil that is also suitable for everyday use.
Marcella, Mike, Johnson, Aaron
Analysis of Cycle-to-Cycle Variation in a Port Injection Gasoline Engine by Simultaneous Measurement of Time Resolved PIV and PLIF2019-32-05521/24/2020
Cycle-to-cycle variation (CCV) of combustion in low load operation is a factor that may cause various problems in engine operation. Variable valve timing and variable ignition timing are commonly used as a means to reduce this variation. However, due to mountability and cost constraints, these methods are not feasible for use in motorcycle engines. Therefore, development of an engine with minimal CCV without utilizing complicated mechanisms or electronic control is required. CCV of combustion may be caused by fluctuations in in-cylinder flow, air-fuel mixture, temperature, residual gas and ignition energy. In this study, the relationship between CCV of combustion, in-cylinder flow fluctuation and air-fuel mixture fluctuation was the primary focus. In order to evaluate in-cylinder flow fluctuation, Time Resolved Particle Image Velocimetry (TR-PIV) technique was utilized. In addition, Planar Laser Induced Fluorescence (PLIF) technique was used to measure spatial distribution of the mixture. These two visualization techniques were used together to measure continuous combustion cycles. The fluctuation of net IMEP can be explained by the fluctuation of Turbulence Kinetic Energy (TKE) and fuel concentration. In most cycles, net IMEP was correlated with TKE. In the remaining cycles, net IMEP was correlated with fuel concentration. The contribution of each factor towards net IMEP is to be discussed. It has been also confirmed that TKE fluctuation is caused by fluctuation in the tumble vortex structure, as shown in the authors' previous study [2] [13].
HARAMIISHI, Santa, WATANABE, Takahiro, IIDA, Minoru, HOKIMOTO, Satoshi, KUBOYAMA, Tatsuya, MORIYOSHI, Yasuo
Study of the Variable Valve Timing Effects on Combustion Quality and Fuel Consumption of an Internal Combustion Engine2019-36-01171/13/2020
The need for a constant evolution of internal combustion engines has encouraged the emergence of new alternatives for the minimization of pollutant emissions, fuel consumption and an increase of the overall performance. The coming years will be marked by the launch of increasingly efficient engines, given the current importance of sustainability in the means of transport. Despite the growing electrification of global mobility, research indicates that the ICE will continue to be the main source of automotive energy in the coming years and, therefore, the study of strategies aimed at optimizing its performance is and will continue to be relevant. In this sense, the purpose of this work is to study the effects of variable valve timing on the experimental calibration of an internal combustion engine intended for research. Different moments of opening and closing of both the intake and exhaust valves were analyzed so that the possible reductions in the specific fuel consumption and the combustion quality improvements could be studied in tests always aimed at maximizing the fuel conversion efficiency. The purpose was to comply with the trend of the current automotive industry, which aims at the production of engines according to international environmental protocols, increasingly restricted in terms of reducing their impact on nature. To this end, two of the most representative fuels in the Brazilian market were tested, the E27 and E100, with particular reference to ethanol, a renewable biofuel with enormous potential to supply the country's future automotive fleet.
Teixeira Malaquias, Augusto César, Diniz Netto, Nilton Antonio, Coelho Baêta, José Guilherme, Teixeira, Alysson Fernandes, Passos Costa, Sérgio Augusto
NUMERICAL MODEL OF SI ENGINE USING GT-POWER CODE2019-36-01701/13/2020
The growing global need for energy and the aggravation of vehicular pollution, associated with a highly competitive market, demand fast and less expensive solutions to develop engine technologies. Numerical simulation has been an effective tool to help meet these needs, as it shortens the time and cost of current engine research. In this scenario, 1-D numerical model has been widely and successful used, presenting excellent results generally with errors around 5% in comparison with experimental data. In this work, the main performance parameters of an in-line four-cylinder SI engine is analyzed through a 1-D simulation using the GT-Power code. A full-scale engine model is set up, which is later calibrated by comparing with experimental data. The numerical methodology is carefully discussed and the methods regarding engine valve diagram and geometrical boundary conditions are also presented. Numerical results of engine power, torque, volumetric efficiency and specific fuel consumption are presented with maximum errors no greater than 7%
Magalhães Avelar, Fausto Torres, Rodrigues Filho, Fernando Antonio, da Costa, Roberto Berlini, Duarte, Vinicius Faria, Magalhães Avelar, Igor Torres, Duarte, Vinicius Faria, Magalhães Avelar, Igor Torres, de Sousa Gama, Heitor Belfort, de Souza, Jose Leoncio Fonseca
Variable Camshaft Valve Timing and its Effects to Hydrous Ethanol (E100) Combustion during Engine Warm up Phase2019-36-01471/13/2020
In-cylinder airflow has significant impact in mixture formation and burn in internal combustion engines. Exhaust valve closing retard and early intake valve opening have large contribution for the in-cylinder airflow. It may reduce pumping work (energy lost to pump exhaust gases out of the cylinder and to draw the fresh air-fuel mixture), hurt combustion stability due to the excess of residual gas in the combustion chamber or still contribute to cylinder scavenging, increasing the amount of fresh air resulting in higher burn efficiency and more work extracted from the cycle. Brazilian market has large Hydrous Ethanol fuel (E100) usage. Due to E100 fuel properties, the intake and exhaust valves opening and closing time must be carefully defined during the engine warm up phase to avoid negative effects on the combustion. The objective of this work is to analyze the effects in performance, combustion stability and emissions, of exhaust valve timing at different engine temperatures when using E100 fuel in a Ford 1.5L naturally aspirated 3-cylinder engine with Port Fuel Injection (PFI) and dual variable valve timing control. The study shows that it is possible to obtain significant emissions improvements during warm up phase by optimizing exhaust valve timing, without exceeding combustion stability limits.
Passarini, Gustavo C., Fregoneze, Marcos, Júnior, Fernando Sarracini
Technique for Front-loading Countermeasures against Deterioration of Sound Quality in Vehicle Interior due to Rapid Combustion in an SI Engine2019-01-230412/19/2019
This paper discusses a technique for the examination of countermeasures at the design stage of the prototype vehicle in order to realize efficient enhancement of the engine combustion noise quality in the vehicle interior. An existing sound quality evaluation method was applied as a simulation technology. The deterioration of the sound quality of combustion noise in the passenger compartment of a new vehicle was estimated from the in-cylinder pressures of a newly developed engine measured on a dynamometer test bench and the structural response functions obtained from the previous mass production vehicle. In addition, the level of reduction in structural response sensitivity necessary for the enhancement of combustion noise quality was estimated for each frequency band. Based on the results, effective countermeasures for the enhancement of combustion noise quality were selected and reflected in the drawings for the initial prototype vehicle. This made it possible to realize the target combustion noise quality in the initial prototype vehicle, which in turn eliminated the necessity for the additional combustion noise countermeasures that have often been applied at the later stages of conventional vehicle development.
Torii, Kenji, Tsuruta, Tatsunori
Enhancing Peak Firing Pressure Limit for Achieving Better Brake Thermal Efficiency of a Diesel Engine2019-01-218012/19/2019
An increased cycle expansion ratio is beneficial from a thermodynamic viewpoint to increase the engine efficiency. In this study, the target compression ratio and corresponding thermodynamic cycle layout were investigated by means of a new ideal combustion cycle. To model the experimental pressure traces, the combustion was divided into three parts; constant volume combustion, early expansion combustion and late combustion. This study discussed optimal parameter values for compression ignition combustion under PFP constraints. These parameters included compression ratio, pressure ratios as well as cut-off ratios. Furthermore, this study experimentally investigated the limitation of thermal efficiency and the variation of energy losses under different geometric compression ratios, boosting pressure and degree of constant volume combustion. These experiments utilized a supercharged single-cylinder heavy duty diesel engine with PFP-capability of up to 30 MPa. In conclusion, it is confirmed that improvement in the indicated thermal efficiency and BTE was achieved by increasing the compression ratio. The trade-off between increased compression ratio and higher losses was also established and an optimum compression ratio found.
Enya, Kenji, Uchida, Noboru
Experimental Proof-of-Concept of HiL Based Virtual Calibration for a Gasoline Engine with a Three-Way-Catalyst2019-01-230112/19/2019
The increasing complexity of modern combustion engines together with the substantial variability of hybrid electric powertrains, lead to new challenges in function development, system integration and vehicle calibration processes. Hardware-in-the-Loop (HiL) simulations have been introduced to front-load part of the testing and calibration tasks from the vehicle to a virtual environment. With this approach, the simulation quality and the cost-benefit ratio are strongly dependent on the accuracy of the plant modelling and the computational effort. This paper introduces a novel HiL simulation platform for an engine control unit (ECU) with a crank-angle resolved real-time model (GT-Power) for a gasoline engine with direct fuel injection, single stage turbocharging and a three-way catalyst. By simplifying the fluid dynamics simulation model from the concept phase, a good compromise between model accuracy and computation speed can be achieved with relatively low effort. The coupling of the engine model and the hardware ECU has been implemented using a realtime workstation with a co-simulation platform (xMOD) coupled to a HiL-simulator with the necessary I/O boards (dSPACE). The closed-loop boost pressure and the air-fuel ratio control by the hardware ECU shows a system behaviour close to the real engine on a dynamometer test bench. The HiL setup can be used to investigate various real driving scenarios for calibration purposes.
Xia, Feihong, Dorscheidt, Frank, Lücke, Stefan, Andert, Jakob, Gardini, Pietro, Scheel, Thomas, Walter, Vitali, Tharmakulasingam, Jaykumar Kansagara Raul, Böhmer, Marius, Nijs, Martin
Oil Transport Phenomena during extreme load transients inside the power cylinder unit as investigated by HS-2DLIF (High-Speed 2D Laser-Induced Fluorescence)2019-01-236312/19/2019
This paper presents findings of optical investigations conducted via the HS-2DLIF (high-speed two-dimensional laser-induced fluorescence) technique under extreme transient conditions. These extreme conditions are a transition from WOT to closed throttle and vice versa. The goal is to gain a better understanding of oil transport magnitudes and timescales for transitions to and from extreme throttled conditions. These conditions are similar to the boundary conditions found during cylinder deactivation. The transients were conducted under motored conditions with injection and spark disabled in a speed range from 650 rpm to 3000 rpm. The load was transitioned from WOT to different low load conditions (closed, 150 mbar and 200 mbar), held at that low load for a variety of durations (10 sec - 600 sec), before going back to WOT. The experiments showed a strong dependence of oil transport on speed and load. The higher the speed, the faster the oil transport. When transitioning to WOT in cases with a lot of oil in the ring pack, a drastic blow-by increase could be measured. The cause of the phenomena could be explained in detail with HS-2DLIF. Previous hypotheses were able to be verified and extended. It was found that, during the time spent at low engine load, oil was transported towards the combustion chamber and into the top ring groove. When a sufficient amount accumulated, the introduction of the transient allowed flow past the top ring, since its sealing capability was lost due to oil blocking its path towards its ID (inner diameter). Additionally, a large amount of oil was pushed through the top ring gap due to reverse flow in collapsing cycles. The top ring collapse ended when enough oil was suddenly released, allowing the ring to regain sealing capabilities.
Ahling, Sebastian, Tian, Tian
Investigation of Particulate Matter Formation in a Diesel Engine Using In-Cylinder Total Sampling and Thermal Desorption-GCMS/Carbon Analysis2019-01-227612/19/2019
In-cylinder total sampling technique utilizing a single-cylinder diesel engine equipped with hydraulic valve actuation system has been developed. In this study, particulate matter (PM) included in the in-cylinder sample gas was collected on a quartz filter, and the polycyclic-aromatic hydrocarbons (PAHs) component and soot were subsequently quantified by thermal desorption-gas chromatograph mass spectrometry (TD-GCMS) and a carbon analyzer, respectively. Cylinder-averaged histories of PAHs and soot were obtained by changing the sampling timing. It was found that decreasing intake oxygen concentration suppresses in-cylinder soot oxidation, and the fuel with higher aromatic and naphthenic contents accelerates soot production.
Furukawa, Shinya, Suzuki, Hirotaka, Shibata, Keiko, Saito, Hiroaki, Miyashita, Kazuya, Ishii, Yoshinori, Shimazaki, Naoki
Simultaneous NO X and CO 2 Reduction for Meeting Future CARB Standards Using a Heavy-Duty Diesel CDA-NVH Strategy03-13-02-001412/10/2019
Commercial vehicles require continual improvements in order to meet fuel consumption standards, improve diesel aftertreatment (AT) system performance, and optimize vehicle fuel economy. Simultaneous reductions in both CO2 and NOX emissions will be required to meet the upcoming regulatory targets for both EPA Phase 2 Greenhouse Gas Standards and new Low NOX Standards being proposed by the California Air Resources Board (CARB). In addition, CARB recently proposed a new certification cycle that will require high NOX conversion while vehicles are operating at lower loads than current regulatory cycles require. Cylinder deactivation (CDA) offers a powerful technology lever for meeting these two regulatory targets on commercial diesel engines. There have been numerous works in the past year showing the benefits of diesel CDA for elevating exhaust temperatures during low-load operation where it is normally too cold for AT to function at peak efficiency. At the same time, CO2 and fuel consumption are reduced through a combination of lower pumping and friction losses and improved thermal efficiency in the cylinders that are still firing. However, CDA has the potential to alter the vehicle vibration, and therefore a strategy must be developed to mitigate these NVH issues while taking advantage of the performance benefits mentioned previously. This article focuses on demonstrating the merits of diesel CDA at low load on a heavy-duty diesel engine in a dynamometer test cell. Results show: 1 An NVH recipe to minimize system vibration when using CDA; 2 Exhaust temperature increase and fuel savings at low load operating modes; 3 Ability to get the AT hot from a cold start using CDA combined with elevated idle speeds; 4 CDA operation over HD FTP and the CARB proposed LLC.
Neely, Gary, Sharp, Chris, Pieczko, Matthew, McCarthy, James E.
Potential for Emission Reduction and Fuel Economy with Micro & Mild HEV2019-28-250411/21/2019
The development of modern combustion engines (spark ignition as well as compression ignition) for vehicles compliant with future oriented emission legislation (BS6, Euro VI, China 6) has introduced several technologies for improvement of both fuel efficiency as well as low emissions combustion strategies. Some of these technologies as there are high pressure multiple injection systems or sophisticated exhaust gas after treatment system imply substantial increase in test and calibration time as well as equipment cost. With the introduction of 48V systems for hybridization a cost- efficient enhancement and, partially, an even attractive alternative is now available. An overview will be given on current technologies as well as on implemented test procedures. The focus will be on solutions which have potential for the Indian market, i.e. solutions which can be implemented with moderate application effort for currently available compact and medium size cars. The possibilities of 48V technologies for fuel economy and emission reduction will be discussed. Simultaneously, tools for testing and calibration at power train testbed as well as for on-road application will be presented. Furthermore, it considers the requirements on the test procedures due to the transition from NEDC to WLTP and the implications of the demand for greater integration of tests under real driving conditions (RDE).
Murr, Franz, Winklhofer, Ernst, Weissbaeck, Michael, Teuschl, Gerald
More sting for the STINGRAY19AUTP11_0211/1/2019
GM Propulsion engineers elevate the evergreen small-block V8 to new heights for its mid-engine Corvette mission. Instead of heaving decades of small-block V8 expertise out the window, GM Propulsion engineers led by chief engineer Jordan Lee leveraged past success to create a new-for-2020 V8. Known as the LT2, the 6.2-L V8 gives Chevy's all-new, eighth-generation 2020 Corvette more power (the most yet in the base Stingray), stirring response, and competitive fuel efficiency compared with the outgoing C7. And the small-block, with its single camshaft in block and two valves per cylinder, remains unmatched versus its rivals in three key metrics: bill of material, package efficiency, and the power-per-dollar quotient. It's the payoff for 65 years of continuously refining (and never giving up on) a brilliant original design.
Sherman, Don
Mahle reveals modular, scalable integrated hybrid powertrain19AUTP11_1011/1/2019
Mahle is developing a complete “fits all, off-the-shelf” modular hybrid-drive propulsion system for a wide range of automakers' models, designed to cut costs, improve packaging and provide a level of electrified-vehicle commonality not seen before in the auto industry. Designated Mahle Modular Hybrid Powertrain (MMHP), the system is modular, scalable and dual-mode (parallel and series). It could be in production within two years, ready to power anything from compact sedans to hefty SUVs. The MMHP integrates an all-new turbocharged gasoline internal-combustion engine in twin- and 3-cylinder forms, customizable gearbox (1-, 2- or 4-speed) and a compact but powerful (choice of power/torque) electric traction motor.
Birch, Stuart
2019 'Create the Future' Automotive/Transportation Category Winner: A Standalone AC BatteryTBMG-3545911/1/2019
Development of Firing Fuel Economy Engine Dyno Test Procedure for JASO Ultra Low Viscosity Engine Oil Standard (JASO GLV-1)2019-01-229610/19/2019
Fuel economy measurement test is one of important engine tests to establish fuel economy engine oil performance standard to support CO2 emission reduction efforts in the automotive industry. On the other hand, it is difficult to develop an engine test without appropriate engine hardware that is designed to utilize low viscosity engine oils. A new firing fuel economy test was developed based on 2ZR-FXE engine designed for hybrid powertrain. The new test procedure aimed to provide the tool to evaluate new low viscosity grades such as 0W-8 and 0W-12 that were adapted in SAE J300 in 2015.
Jikuya, Hiroshi, Mori, Shunsuke, Yamamori, Kazuo, Hirano, Satoshi
Parametric Calculation and Significance of Engine Dynamic Torque in Performance Benchmarking of a Vehicle2019-28-002810/11/2019
The automotive industries around the world is undergoing massive transformation towards identifying technological capabilities to improve vehicle performance. In this regard, the engine dynamic torque plays a crucial role in defining the transient performance and drivability of a vehicle. Moreover, the dynamic torque is used as a visualization parameter in performance prediction of a vehicle to set the right engineering targets and to assess the engine potential. Hence, an accurate measurement and prediction of the engine dynamic torque is required. However, there are very few methodologies available to measure the engine dynamic torque with reasonable accuracy and minimum efforts. The measurement of engine brake torque using a torque transducer is one of the potential methods. However, it requires a lot of effort and time to instrument the vehicle. It is also possible to back-calculate the engine torque based on fuel injection quantity and other known engine parameters. Though this calculation method is relatively easy, it is not an accurate method. Moreover, it would not be possible to extract engine information of benchmark vehicles. Since every method has their own capabilities, limitations and none of them are effective to capture real transient torque behaviour of an engine, this work elaborates about a distinct methodology to calculate dynamic torque and its role in performance prediction and benchmarking of a vehicle with reduced effort and time. In this method, dynamic torque of an engine is counter calculated from vehicle speed at individual gears taking inertial resistance into account along with drag force, driveline ratios and efficiency. Calculated dynamic torque is given as input to vehicle system simulation software. Corresponding performance number arrived from the vehicle model is validated with the experimental test results. The outcomes are found to have excellent correlation which makes this approach efficient and executable for better prediction of performance and selection of appropriate drivetrain configuration in early developmental stage of a vehicle. Moreover, this approach can be used for assessing the dynamic torque of benchmark vehicles too.
Ramani, Praveen Kumar, Jayaraman, Bharathraj, Thiruppathi, Sangeetha Ramasamy
Quantification of Linear Approximation Error for Model Predictive Control of Spark-Ignited Turbocharged Engines2019-24-00149/9/2019
Modern turbocharged spark-ignition engines are being equipped with an increasing number of control actuators to meet fuel economy, emissions, and performance targets. The response time variations between engine control actuators tend to be significant during transients and necessitate highly complex actuator scheduling routines. Model Predictive Control (MPC) has the potential to significantly reduce control calibration effort as compared to the current methodologies that are based on decentralized feedback control strategies. MPC strategies simultaneously generate all actuator responses by using a combination of current engine conditions and optimization of a control-oriented plant model. To achieve real-time control, the engine model and optimization processes must be computationally efficient without sacrificing effectiveness. Most MPC systems intended for real-time control utilize a linearized model that can be quickly evaluated using a sub-optimal optimization methodology. Online linearization of the engine model is computationally expensive so it should be performed as infrequently as possible. Since engine dynamics are non-linear, a local linearity approximation error occurs during this process. This research presents a method of evaluating the impact of local linear approximation error on the modeled engine torque for a range of operating conditions. Transient experiments show a clear deviation between a non-linear model and its linearized version, which also depends on the type of transient induced. Step transients in engine torque are generally more forgiving with respect to the number of model linearization calculations required as compared to sinusoidal transients. The sinusoidal transients clearly show a narrow frequency range where the deviation in the models is highest.
Koli, Rohit, Egan, Daniel, Zhu, Qilun, Prucka, Robert
A Practical Recuperated Split Cycle Engine for Low Emissions and High Efficiency2019-24-01909/9/2019
The Recuperated Split Cycle Engine is a new type of ICE, offering a step change in efficiency and tailpipe emissions. It targets the heavy duty, long-haul sector (trucks, off-highway, rail, shipping), where electrification is most challenging, and distributed generation, where capacity is required to support rising electrification. The engine separates cold (induction, compression) and hot (combustion, expansion) parts of the cycle; waste exhaust heat is recovered between them via a recuperator, as in a recuperated gas turbine. Recent research presented at this conference [1] shows that the sonic airflows seen in the induction event give rise to extraordinary fuel mixing and clean, cool combustion, with potential for after-treated emission levels between SULEV and zero-impact (either unmeasurable or below ambient). Recuperation and thermal insulation of the hot cylinder (both feasible within the capability of common materials) also enable high thermal efficiency, with a flatter efficiency map than a conventional ICE. Combining the two attributes, and introducing sustainable fuels, places this readily manufactured, affordable technology on a par with battery-electric and fuel cell propulsion. Results from simulation to optimise the concept are described. A Ricardo WAVE model was built, with validation of key inputs such as valve breathing, heat transfer and burn-rates from relevant experimental research data. The model was used to develop the cycle around three concepts - a basic layout, “ThermoPower”, was shown to be capable of over 10% fuel saving; “Wet ThermoPower” uses water injection as a compression coolant for greater efficiency, while the ultimate “CryoPower” injects Liquid Nitrogen for quasi-isothermal compression and charge dilution. The optimisation process and practical details are described, especially the development of the critical recuperator, which is subjected to high pressure and temperature; management of its thermal expansion and manufacturing process have been optimised to minimise add-cost over a current ICE bill of materials.
Owen, Nicholas, Treccarichi, Fabrizio, Atkins, Andrew, Selvaraj, Anoop, Barnes, David, Besant, Tanzi, Morgan, Robert
Zero-Dimensional Heat Release Modeling Framework for Gasoline Compression-Ignition Engines with Multiple Injection Events2019-24-00839/9/2019
A zero-dimensional heat release model was developed for compression ignition engines. This type of model can be utilized for parametric studies, off-line optimization to reduce experimental efforts as well as model-based control strategies. In this particular case, the combustion model, in a simpler form, will be used in future efforts to control the combustion in compression ignition engines operating on gasoline-like fuels. To allow for a realistic representation of the in-cylinder combustion process, a spray model has been employed to allow for the quantification of fuel distribution as well as turbulent kinetic energy within the injection spray. The combustion model framework is capable of reflecting premixed as well as mixing controlled combustion. Fuel is assigned to various combustion events based on the air-fuel mixture within the spray. The mixing controlled combustion consists of two separate combustion events; one occurring within the fuel spray, which is characterized by rich fuel mixtures with a substantial level of turbulent kinetic energy and high combustion rates; the other one describes moderate combustion rates of lean fuel mixtures with less turbulent kinetic energy. Model constants were calibrated against experimental data from a 12.4L heavy-duty compression ignition engine operated on gasoline for various sweeps at 14bar BMEP and mostly at an engine speed of 1038rpm. A maximum prediction error in combustion phasing of 1.3CAD was found across the 30 calibrated sample points.
Pamminger, Michael, Hall, Carrie, Wang, Buyu, Wallner, Thomas, Rajkumar, M
Fuel Consumption and Pollutant Emission Optimization at Part and Full Load of a High-Performance V12 SI Engine by a 1D Model2019-24-00809/9/2019
Modern internal combustion engines show complex architectures in order to improve their performance in terms of brake torque and fuel consumption. Concerning naturally-aspirated engines, an optimization of the intake port geometry, together with the selection of a proper valve timing, allow to improve the cylinder filling and hence the performance. The identification of an optimal calibration strategy at test bench usually requires long and expensive experimental activities. Numerical tools can help to support engine calibration, especially in the early design phases. In the present work, a 12-cylinder naturally aspirated spark ignition engine is investigated. The engine is experimentally tested under full and part load operations. Main performance parameters, in-cylinder pressure cycles and raw pollutant emissions are measured. The engine is schematized in a one-dimensional model (GT-Power™), where “user routines” are employed to simulate turbulence, combustion, knock and pollutant production. 1D model is validated against the experimental data, denoting a good accuracy. A calibration procedure is implemented by an external optimizer, coupled with the 1D engine model, with the aim of minimizing the fuel consumption. The procedure decision parameters are intake and exhaust valve timings, and combustion phasing. Proper constraints are posed for residual gas fraction and knock intensity. The optimal calibration strategies have been recognized for two operating conditions, where the engine most frequently works along an RDE driving cycles. Main drivers for engine efficiency are intake de-throttling at part load, thanks to the internal EGR caused by a Miller-Atkinson valve strategy, and cylinder filling maximization at high load. A ‘virtual’ calibration of the considered engine, employing the developed automatic procedure, is identified on completely theoretical basis. The proposed methodology shows the capability to drive and support the experimental engine calibration and presents the potential to be very helpful in reducing the related costs and time-to-market.
De Bellis, Vincenzo, Malfi, Enrica, Cacciatore, Diego, Aliperti, Antonio, Rizzi, Luca
CFD Modeling of Gas Exchange, Fuel-Air Mixing and Combustion in Gasoline Direct-Injection Engines2019-24-00959/9/2019
Gasoline, direct injection engines represent one of the most widely adopted powertrain for passenger cars. However, further development efforts are necessary to meet the future fuel consumption and emission standards imposing an efficiency increase and a reduction of particulate matter emissions. Within this context, computational fluid dynamics is nowadays a consolidated tool to support engine design; this work is focused on the development of a set of CFD models for the prediction of combustion in modern GDI engines. The one-equation Weller model coupled with a zero-dimensional approach to handle initial flame kernel growth was applied to predict flame propagation. To account for mixture fraction fluctuations which might lead to the presence of soot precursor species, burned gas chemical composition is computed using tabulated kinetics with a presumed probability density function. Assessment of the combustion model was done with experimental data of flame radius evolution at different operating conditions. Afterwards, simulations were carried out for a turbocharged gasoline, direct-injection engine with a variable valve actuation. Different operating points were considered including variations of speed and load: a detailed comparison was performed between computed and experimental data of in-cylinder pressure and apparent heat release rate.
Lucchini, Tommaso, D'Errico, Gianluca, Paredi, Davide, Sforza, Lorenzo, Onorati, Angelo
Optical Investigation of Mixture Formation in a Small Bore DISI Engine by Laser Induced Exciplex Fluorescence (LIEF)2019-24-01339/9/2019
Legislative and customer demands in terms of fuel consumption and emissions are an enormous challenge for the development of modern combustion engines. Downsizing in combination with turbocharging and direct injection is one way to increase efficiency and therefore meet the requirements. This results in a reduction of the displacement and thus the bore diameter. The emerging trends towards long-stroke engine design and hybridization make the use of small bore diameters in future gasoline engines a realistic scenario. The application of direct injection with small cylinder dimensions increases the probability of the interaction of liquid fuel with the cylinder walls, which may result in disadvantages concerning especially particulate emissions. This leads to the question which bore diameter is feasible without drawbacks concerning emissions as a result of wall wetting. In the previous project “GDI Boundary Bore” the feasibility of an SI engine with direct injection and small bore diameter (60 mm) was shown by the analysis of two different cylinder head concepts (3V and 4V). For the acquirement of deeper understanding of the mixture formation in such engines the laser induced exciplex fluorescence (LIEF) was applied on a transparent engine in a follow up project for the simultaneous visualization of the vapor and liquid phase. The optical investigation on the transparent single cylinder engine included various operating points with variation of the start of injection. Within the scope of the investigations on the 3V concept, it was possible to determine why a charge movement flap increasingly loses its influence with early injection. The optical investigations on the 4V concept showed that a 7-hole injector with a lower penetration depth has disadvantages compared to a 6-hole injector. Furthermore, it was possible to determine why a charge movement flap can have a negative effect on mixture formation, contrary to common opinion.
Pauls, Alexander, Eilts, Peter
Optimization of the Exhaust Aftertreatment System of a Heavy Duty Diesel Engine by Means of Variable Valve Timing2019-24-01439/9/2019
In view of the current political debate, it can be assumed that the nitrogen oxide limits for commercial vehicles will be further reduced. This is also demonstrated by the currently voluntary certification of the CARB Optional Low NOX legislation, which requires nitrogen oxide emissions of 0.027 g/kWh. This corresponds to a reduction of 93 % compared to the current EU VI standard. Therefore, the optimization of EAT systems represents an essential research focus for future commercial vehicle applications. One way to optimize the EAT system may be the usage of variable valve actuation. Existing investigations show an exhaust gas temperature increase with intake valve timing adjustment, also known as Miller timing. But the authors conclude that it cannot accelerate the warm up process. With regard to the effects on the exhaust aftertreatment system and the resulting tailpipe emissions, only improved HC and CO oxidation could be identified so far. In addition, a potential for improved NOX reduction is expected in the exhaust gas temperature increase. Therefore, further investigations have been carried out. The investigations presented in this paper are based on test bench measurements of characteristic points in the WHTC on a single-cylinder commercial vehicle engine, which are then evaluated by a detailed pressure analysis. In combination with validated simulation models of a commercial vehicle series engine and its exhaust aftertreatment system, the effects of the Miller timing on the exhaust aftertreatment are investigated. The results show an improved SCR efficiency, DPF regeneration and also a decreased EAT cool down in the partial load range. Additionally, a change in the NO2/NOX ratio before the SCR system can be detected. This leads to lower nitrous oxide emissions, given by a suitable choice of valve timing. Therefore, variable valve timing can contribute to fulfil future emission legislations.
Betz, Marius, Eilts, Peter
Development of a Predictive Model for Knock Intensity in a Spark-Ignition Engine with Gasoline-Ethanol-nButanol Blend Fuel by Using Rapid Compression Machine2019-24-01259/9/2019
In this study, we developed a predictive model for knock intensity in spark-ignition (SI) engine with gasoline-ethanol-nbutanol (GEnB) blend fuel, which is being considered as an alternative fuel for conventional gasoline in South Korea, to understand the potential improvement of engine performance with the introduction of GEnB blend fuel. First, the ignition delay of the stoichiometric mixture of GEnB blend fuel and air was measured on a pressure of 10-30 bar and a temperature of 721-831 K by using rapid compression machine (RCM). Then, we derived the empirical correlation of the ignition delay with which the Livengood-Wu integration along pressure-temperature profile in RCM gives the best prediction for the start of combustion. The ignition delay correlation was applied to 0-D two-zone SI engine model, and we predicted the knocking intensity of GEnB blend fuels by using Livengood-Wu integration and Bougrine’s knocking intensity model. The model was validated by comparing the research octane number (RON) calculated from the model with the reference based on the cooperative fuel research (CFR) engine experiment. Consequently, it was found that the knocking prediction model properly predict RON of various GEnB blend fuels. The developed model was manipulated to predict the potential improvement of knock-limited region of modern SI engine with GEnB blend fuel, and we found that the knock-limited nIMEP increases by 1.86% as alcohol content increases by 1 % of ethanol equivalent alcohol content.
Cho, Jaeyoung, Song, Han Ho
Definition of a Methodology Promoting the Use of 1D Thermo-Fluid Dynamic Analysis for the Reduction of the Experimental Effort in Engine Base Calibration2019-24-00139/9/2019
Over the last decades, internal combustion engines have undergone a continuous evolution to achieve better performance, lower pollutant emissions and reduced fuel consumption. The pursuit of these often-conflicting goals involved changes in engine architecture in order to carry out advanced management strategies. Therefore, Variable Valve Actuation, Exhaust Gas Recirculation, Gasoline Direct Injection, turbocharging and powertrain hybridization have found wide application in the automotive field. However, the effective management of a such complex system is due to the contemporaneous development of the on-board Engine electronic Control Unit. In fact, the additional degrees of freedom available for the engine regulation highly increased the complexity of engine control and management, resulting in a very expensive and long calibration process. To overcome these drawbacks, an effective methodology based on the adoption of 1D thermo-fluid dynamic analysis is proposed in this study. In particular, starting from a complete experimental set of data actually used for the base calibration of a reference spark ignition engine, a novel procedure based on vector optimization approach is used to reliably calibrate a 1D engine model starting from a reduced experimental dataset. Once validated, the engine model is then used as a virtual test bench to reproduce the experimental campaign numerically, thus obtaining a detailed and complete dataset exploitable for calibration purposes, here called numerical or virtual dataset. To verify the potential of the proposed methodology, experimental and virtual dataset have been finally compared. The research clearly demonstrates the effectiveness of the proposed approach since the average errors are comparable with the measurement errors. Therefore, the methodology shows promising results concerning the use of numerical dataset obtained from reliable 1D CFD engine models as input to computer aided calibration software. This way, a significant cut to the experimental campaign required for calibration purposes is achieved, with their related times and costs.
de Nola, Francesco, Giardiello, Giovanni, Gimelli, Alfredo, Molteni, Andrea, Muccillo, Massimiliano, Tortora lng, Roberto
Impact of Cooled EGR on Performance and Emissions of a Turbocharged Spark-Ignition Engine under Low-Full Load Conditions2019-24-00219/9/2019
The stringent worldwide exhaust emission legislations for CO2 and pollutants require significant efforts to increase both the combustion efficiency and the emission quality of internal combustion engines. With this aim, several solutions are continuously developed to improve the combustion efficiency of spark ignition engines. Among the various solutions, EGR represents a well-established technology to improve the gasoline engine performance and the nitrogen-oxides emissions. This work presents the results of an experimental investigation on the effects of the EGR technique on combustion evolution, knock tendency, performance and emissions of a small-size turbocharged PFI SI engine, equipped with an external cooled EGR system. Measurements are carried out at different engine speeds, on a wide range of loads and EGR levels. The standard engine calibration is applied at the reference test conditions. Then, the exhaust gas is recirculated and the load is controlled by adjusting the intake pressure, the injection and the spark timing. The main results show a significant reduction in specific fuel consumption at low load due to the lower pumping losses when EGR is active, independent on the engine speed. At high load, a lower improvement in fuel economy has been found, mainly due to a slight reduction in the knock tendency. EGR results in a reduction in NO emission at each engine speed and load, with penalties in HC emission.
Marchitto, Luca, Tornatore, Cinzia, Valentino, Gerardo, Teodosio, Luigi
Numerical and Experimental Investigation into Brake Thermal Efficiency Optimum Heat Release Rate for a Diesel Engine2019-24-01099/9/2019
According to thermodynamic analysis of ideal engine cycles, Otto cycle thermal efficiency exceeds that of the Diesel and Sabathe (or Dual) cycles. However, zero-dimensional calculations indicated that the brake thermal efficiency (BTE) of an actual Otto or Diesel engine could be higher with a Sabathe (or Seilliger) type cycle, within a limited peak firing pressure (PFP). To confirm these results with an actual engine, a three-injector combustion system (center and two sides) was utilized to allow more flexibility in the heat release rate (HRR) profile than the conventional single injector system in the previous study. The experimental result was qualitatively consistent with the calculated results even though its HRR had less peak and longer duration than ideal. In this study, a new thermodynamic cycle with higher HRR in the expansion stroke than the ideal Sabathe cycle, was thus developed. The proposed (higher) HRR was achieved by overlapped fuel injection with the three injectors. Experimental results were qualitatively consistent with calculations, though the measured HRR had a lower peak value and longer duration. Three-dimensional analysis using the CONVERGE computational fluid dynamics (CFD) software package was also performed in order to obtain a complementary view of the test results. Numerical and experimental results were quite similar, showing improvement in BTE for increased overlap of center and side injections, but only up to a certain level. For near-simultaneous injection, the experimental BTE rapidly deteriorated, whereas the numerical BTE deteriorated only slightly and remained higher than measured values. Analysis of both direct in-cylinder combustion images and three-dimensional numerical simulations revealed that spray-to-spray interference could strongly affect mixture formation (local fuel/air equivalence ratio).
Uchida, Noboru, GALPIN, Jeremy, Watanabe, Kazumasa, Enya, Kenji, Zaccardi, Jean-Marc, Duffour, Florence
Driving Cycle and Elasticity Manoeuvres Simulation of a Small SUV Featuring an Electrically Boosted 1.0 L Gasoline Engine2019-24-00709/9/2019
In order to meet the CO2 emission reduction targets, downsizing coupled with turbocharging has been proven as an effective way in reducing CO2 emissions while maintaining and improving vehicle driveability. As the downsizing becomes widely exploited, the increased boost levels entail the exploration of dual stage boosting systems. In a context of increasing electrification, the usage of electrified boosting systems can be effective in the improvement of vehicle performances. The aim of this work is therefore to evaluate, through numerical simulation, the impact of different voltage (12 V or 48 V) electric superchargers (eSC) on an extremely downsized 1.0L engine on vehicle performance and fuel consumption over different transient manoeuvres. The virtual test rig employed for the analysis integrates a 1D CFD Fast Running Model (FRM) engine representative of a 1.0L state-of-the-art gasoline engine featuring an eSC in series with the main turbocharger, an electric network (12 V or 48 V), a six speed manual transmission and a vehicle representative of a B-SUV segment car. A preliminary assessment of the steady state performances of the 1.0L engine with the electrified dual boosting system with both 12 V and 48 V electric supercharger was performed. Then, the vehicle performances were evaluated by means of, on the one hand, vehicle elasticity manoeuvres for the performance assessment and, on the other hand, type approval and RDE driving cycles, for the fuel economy assessment. An evaluation of possible engine and vehicle hardware modifications was also carried out. In particular, the effect of a variation of the final drive ratio, the increase of the turbine size and the usage of a high efficiency engine concept (featuring an increased compression ratio from 10 to 12 and a late intake valve closing, exploiting the advantages of a Miller cycle) were investigated.
Zanelli, Alessandro, Millo, Federico, Barbolini, Marco
Performance and Emissions of an Advanced Multi-Cylinder SI Engine Operating in Ultra-Lean Conditions2019-24-00759/9/2019
In this work the performance and noxious emissions of a prototype Spark Ignition (SI) engine, working in ultra-lean conditions, are investigated. It is a four-cylinder engine, having a very high compression ratio, and an active pre-chamber. The required amount of air is provided by a low-pressure variable geometry turbocharger, coupled to a high-pressure E-compressor. The engine is equipped with a variable valve timing device on the intake camshaft. The goal of this activity is to support the development and the calibration of the described engine, and to exploit the full potential of the ultra-lean concept. To this aim, a combustion model for a pre-chamber engine, set up and validated in a previous paper for a similar single-cylinder unit, is utilized. It is coupled to additional in-house developed sub-models, employed for the prediction of the in-cylinder turbulence, heat transfer, knock and pollutant emissions. Such a complex architecture, schematized in a commercial 1D modeling framework, presents several control parameters which have to be properly selected to maximize the engine efficiency and minimize the noxious emissions over its whole operating domain. A Rule-Based (RB) calibration strategy is hence implemented in the 1D model to identify the optimal values of each control variable. The reliability of the RB calibration is also demonstrated through the comparison with the outcomes of a general-purpose optimizer, over a load sweep at a constant speed. The 1D model and the RB methodology are then applied for the performance prediction over the whole engine operating domain. The predicted performances show the possibility to achieve a wide zone of very high efficiency, with limited penalizations only at very low loads. Main advantages of the lean-combustion concept are highlighted, concerning a higher specific heat ratio, reduced heat losses, improved knock mitigation, and abatement of pollutant emissions, especially regarding CO and NOx. The presented methodology demonstrates to be a valuable tool to support the development and calibration of the considered high-efficiency engine architecture.
Bozza, Fabio, Tufano, Daniela, Malfi, Enrica, Teodosio, Luigi, LIBERT, Cédric, De Bellis, Vincenzo
Back-Pressure and Fuel Type Effects on Exhaust Gas Oxygen Sensor Readings for a Single Cylinder Spark Ignition Engine Running on Gasoline and Ethanol2019-24-00469/9/2019
Application of more and more complex control strategies in spark ignition (SI) engines is required for ensuring high conversion efficiency and effective emissions reduction. Closed loop fuel injection is being implemented on an ever wider scale in small size SI units that generally feature single cylinder architecture. For such systems the readings from the exhaust gas oxygen sensor are essential for controlling air-fuel ratio and indirectly combustion. The present study looked at the influence of pressure oscillations on the values given by the sensor, for different equivalence ratio settings in wide open throttle conditions for an experimental SI unit. As expected, the readings were found to be influenced by pressure oscillations in the exhaust line during lean operation, while with stoichiometric and rich fueling the effects were minimal. Fuel type was also found to be an important aspect. Gasoline was compared to ethanol, and the latter underlined the effect of combustion efficiency on how the sensor readings need to be interpreted. Quasi-dimensional simulation using the GT-Power software was also used to provide further insight into the correlation between combustion phenomena and read air-fuel ratio. Following the combined experimental and numerical approach, the bases were put for defining an algorithm capable of compensating the effects of pressure oscillations without the need for an additional sensor.
Irimescu, Adrian
Water Injection Contribution to Enabling Stoichiometric Air-to-Fuel Ratio Operation at Rated Power Conditions of a High-Performance DISI Single Cylinder Engine2019-24-01739/9/2019
The next generation of gasoline turbo-charged engines will have to deal with the continuous tightening of emissions regulations. In fact, to better represent real-world emission figures, WLTP and RDE cycles focus on stricter criteria; spanning higher speeds and loads potentially covering the whole engine operating map. It is common practice at present to use overfueling to avoid catastrophic failure of turbine and aftertreatment systems at very high engine speeds and loads due to excessive temperatures. A past technology, which is presently enjoying a resurgence of interest, is water injection. In particular, for high-specific-power applications, this could be used as replacement strategy for overfueling, potentially enabling full operating range stoichiometric operation with no compromise in terms of maximum performance with respect to today. In order to validate this scenario, an experimental campaign on a single cylinder engine has been carried out to highlight port water injection benefits and possible limitations at high engine speed and loads. A dedicated port injector has been characterized in a spray bomb and 3D-CFD simulations have been performed with the goal of better understanding and illustrating the air cooling effect along the water pathway from the injector tip to the cylinder charge. Detailed chemical thermo-kinetics modelling of gasoline/water gaseous mixtures was used to help separate thermal from chemical effects arising from use of a water injection system. A number of injector types, locations, water flow rates and inlet valve timings have been included in the study in order to fully explore the potential benefits of this technology.
Paltrinieri, Stefano, Mortellaro, Fabio, Silvestri, Nicola, Rolando, Luciano, Medda, Massimo, Corrigan, Daire
Development of Valve Train Configurations Optimized for Cold Start and Their Effect on Diesel Soot Emission2019-24-01619/9/2019
The continuous pursuit of more efficient diesel engines and the stricter emission regulations with the introduction of the Real Driving Emissions test (RDE) necessitate further investigations of heating strategies and their suitability in terms of series production. Under these circumstances heating strategies of a variable valve train for a single-cylinder research diesel engine have been first simulated and then experimentally tested at the Institute of Internal Combustion Engines of the Karlsruhe Institute of Technology (KIT). By combining statistical experimental design (DoE) and 1-D gas exchange simulations, empirical DoE models for the design of suitable camshaft configurations have been established. After having performed a potential assessment, the most favorable configurations were manufactured and subsequently tested. The configuration with an additional opening of an outlet valve during the intake stroke (2nd Event) shows the best compromise between engine out HC/CO emissions and an efficient exhaust gas temperature increase. The strategy-related state changes in the combustion chamber when using a 2nd Event and the resulting soot characteristics, in terms of size and distribution, resulting reactivity and filter soot number, are subject of the second research phase. For the exact characterization of the resulting soot and for the detailed base collation, the size distribution and the soot reactivity were further investigated - in addition to the number of soot particles. In the context of these investigations, the internal engine soot formation and oxidation processes were analyzed by means of the extended two-color pyrometry. The final results of the direct comparison of the individual camshaft configurations help to make a statement at an early stage of the development process as to whether the effects of the heating strategy harmonize with the present aftertreatment system or need to be adapted to the new soot reactivity.
Maniatis, Panagiotis, Erforth, Daniel, Wagner, Uwe, Koch, Thomas
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