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Gradationally Controlled Voltage Inverter for More Electric Aircrafts

IHI Corporation-Hitoshi Oyori
Mitsubishi Electric Corp.-Tetsuya Kojima, Masahiro Sugahara, Yusuke Shirouchi, Hisatoshi Fukumoto, Akihiko Iwata
  • Technical Paper
  • 2019-01-1913
To be published on 2019-09-16 by SAE International in United States
Over recent decades, there has been a lot of progress toward a more electric aircraft (MEA) to reduce emissions and fuel consumption. In MEAs, many subsystems that previously used hydraulic or pneumatic power have been replaced by electrical systems with inverters and electrical machines. Therefore, MEAs reduce the weight, i.e. fuel consumption, and maintenance cost. To achieve advanced electrical systems, the weight of inverters has significant importance. In this work, a gradationally controlled voltage (GCV) inverter is proposed to reduce the weight and enhance reliability. A GCV inverter can supply gradational quasi-sinusoidal voltages combining two different voltages from a 3-phase 3-level (main) inverter and three single-phase H-bridge (sub) inverters. A dc power supply is required only for the main inverter. A main inverter with Si-IGBTs supplies the fundamental voltage by only one switching in the fundamental period. Consequently, the switching loss is minimized and hence the weight of cooling systems can be reduced. Sub inverters, which have the half of dc-link voltage of the main inverter, employ SiC-MOSFETs with higher switching frequency and compensate for…

Flight Optimization Model on Global and Interval Ranges for Conceptual Studies of MEA Systems

Akita University-Yotsugi Shibuya
IHI Corporation-Hitoshi Oyori, Hirotaka Sugawara, Naoki Seki
  • Technical Paper
  • 2019-01-1906
To be published on 2019-09-16 by SAE International in United States
In development of more electric aircraft applications, it is important to discuss aircraft energy management on various level of aircraft operation. This paper presents a computationally efficient optimization model for evaluating flight efficiency on global and interval flight ranges. The model is described as an optimal control problem with an objective functional subjected to state condition and control input constraints along a flight path range. A flight model consists of aircraft point-mass equations of motion including engine and aerodynamic models. The engine model generates the engine thrust and fuel consumption rate for operation condition and the aerodynamic model generates the drag force and lift force of an aircraft for flight conditions. These models is identified by data taken from a published literature as an example. First, approximate optimization process is performed for climb, cruise, decent and approach as each interval range path. Next, optimization for global range path involves whole flight path to find optimal operation condition in the flight. In aircraft energy management, fuel consumption converts into not only thrust power, but power of…

Optical investigation of mixture formation in a small bore DISI engine by laser induced exciplex fluorescence (LIEF)

Technische Univ. Braunschweig-Alexander Pauls, Peter Eilts
  • Technical Paper
  • 2019-24-0133
To be published on 2019-08-15 by SAE International in United States
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 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. The emerging trends towards long-stroke engine design and hybridization make the use of small bore diameters in future gasoline engines a realistic scenario. In the previous project “GDI Boundary Bore” the feasibility of an SI engine with direct injection and small bore diameter was shown by the analyses of two different cylinder head concepts (3V and 4V). For the acquirement of deeper understanding of the mixture formation in such engines…

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

Vienna University of Technology-Bastian Beyfuss, Peter Hofmann, Bernhard Geringer
  • Technical Paper
  • 2019-24-0204
To be published on 2019-08-15 by SAE International in United States
The efficiency of a Hybrid Electric Vehicle (HEV) depends strongly on its implemented energy management strategy (EMS) that splits the drivers torque request onto the internal combustion engine (ICE) and electric motor (EM). For calibrating these EMS, usually, steady-state efficiency maps of the power converters are used. These charts are mainly derived from measurements under optimal conditions. However, while the EM’s efficiency can indeed be considered stable, the efficiency of a ICE fluctuates strongly under different conditions. Among others, these fluctuations can be induced by charge air temperature, engine oil temperature or the fuel’s knock resistance. This paper proposes a new approach for predicting the impact of any external influence onto the ICE efficiency. This is done by computing the actual deviation from the optimal reference ignition timing and adjusting the result by actual oil temperature and target air-to-fuel ratio. For calibrating, only a fuel consumption map, measured under random conditions, and some warm-up measurements are required. The efficiency prognosis is evaluated with measurements from the engine test bench. With this method being real time…

Analysis of Water Injection Strategies to Exploit the Thermodynamic Effects of Water in Gasoline Engines by Means of 3D-CFD Simulations

Brandenburg Univ of Technology-Tim Franken, Corinna Netzer
FKFS Stuttgart-Marco Chiodi
  • Technical Paper
  • 2019-24-0102
To be published on 2019-08-15 by SAE International in United States
CO2 emission constraints taking effect from 2020 lead to further investigate technologies to lower knock sensitivity of gasoline engines, main limiting factor to increase engine efficiency and thus reduce fuel consumption. Moreover the RDE cycle demands for higher power operation, where fuel enrichment is needed for component protection. To achieve high efficiency, the engine should be run at stoichiometric conditions in order to have better emission control and reduce fuel consumption. Among others, water injection is a promising technology to improve engine combustion efficiency and to keep high conversion rates of the TWC over the whole engine map. The comprehension of multiple thermodynamic effects of water injection through 3D-CFD simulations and their exploitation to enhance the engine combustion efficiency is the main purpose of the analysis. As basis for the research a single cylinder engine derived from a 1l turbocharged 3-cylinders engine is used to evaluate indirect and direct water injection. The entire engine flow field is reproduced and analyzed with 3D-CFD simulations and numerical models are employed to separate the influence of chemical and…

Emissions Optimization Potential of a Diesel Engine Running on HVO: A Combined Experimental and Simulation Investigation

Aristotle University of Thessaloniki-Athanasios Dimaratos, Stylianos Doulgeris, Zissis Samaras
Centre For Research & Technology Hellas-Athanasios Dimitriadis, Stella Bezergianni
  • Technical Paper
  • 2019-24-0039
To be published on 2019-08-15 by SAE International in United States
The present work investigates some recalibration possibilities of a 1.4l common rail turbo-charged diesel engine for the optimal operation in terms of emissions and fuel consumption (FC) with pure Hydrotreated Vegetable Oil (HVO). Initially, steady-state experimental data with nominal engine settings revealed HVO benefits as a drop-in fuel. Under these conditions, pure HVO is associated with lower engine out PM (up to 75%) and CO2 (up to 10%) emissions, and lower mass-based FC (up to 9%), while NOx are similar or slightly higher to diesel fuel. At the next step, a combustion model was developed for the particular engine targeting to identify the optimal IT (Injection Timing) and EGR settings for further emissions (PM, NOx and CO2) and FC reduction with pure HVO. For this purpose, four re-adjusted IT and EGR maps were developed with both conventional diesel and HVO. The results of the combustion model in steady-state conditions showed clear reductions in NOx (up to 45%), PM (up to 70%) and CO2 (up to 6%) emissions and in fuel mass consumed (up to 6%)…

Friction reduction by optimization of local oil temperatures

Universitat of Stuttgart-Michael Bargende
University of Kassel-Oemer Oezdemir, Adrian Rienäcker
  • Technical Paper
  • 2019-24-0177
To be published on 2019-08-15 by SAE International in United States
The reduction of engine-out emissions and increase of the total efficiency is a fundamental approach to reduce the fuel consumption and emissions of vehicles driven by combustion engines. Conventional passenger cars are operated mainly in lower partial loads most of their lifetime. Under these conditions, oil temperatures which are far below the maximum temperatures allowed, dominate inside the journal bearings. Therefore, the objective of this research project was to investigate possible potentials of friction reduction by optimization of the thermal management of the oil circuit of a combustion engine. Within the engine investigations, it was shown that especially the friction of the main and connecting rod bearings can be reduced with an increase of the oil supply temperature. For the investigations, the oil circuit of the test engine was modified to realize three separate oil circuits of main and connecting rod bearings, cylinder head and the piston jets with turbocharger, that were individually supplied with oil at different pressures and temperatures by an external system. Furthermore, on a journal bearing test rig it was shown…

Injection Pattern Investigation for Gasoline Partially Premixed Combustion Analysis

MAGNETI MARELLI SpA - Div. Powertrain-Federico Stola, Matteo De Cesare
University of Bologna-Fabrizio Ponti, Vittorio Ravaglioli, Giacomo Silvagni
  • Technical Paper
  • 2019-24-0112
To be published on 2019-08-15 by SAE International in United States
Nowadays, compression-ignited engines are considered the most efficient and reliable technology for automotive applications. However, mainly due to the current emission regulations, that require increasingly stringent reductions of NOx and particulate matter, the use of diesel-like fuels is becoming a critical issue. For this reason, a large amount of research and experimentation is being carried out to investigate innovative combustion techniques suitable to simultaneously mitigate the production of NOx and soot, while improving engine efficiency. In this scenario, the combined use of compression-ignited engines and gasoline-like fuels proved to be very promising, especially in case the fuel is directly-injected in the combustion chamber at high pressure. The presented study analyzes the combustion process produced by the direct injection of gasoline in a compression-ignited light-duty engine. The engine under investigation has been modified to guarantee a stable engine operation over its whole operating range, that is achieved controlling boost pressure and temperature together with the design of the multiple injections pattern. The analysis of the experimental tests highlights the impact of several control variables on combustion…

Development of 1D/0D cycle simulation model for highly lean burn SI engine operation

Chiba Univ.-Tatsuya Kuboyama
  • Technical Paper
  • 2019-24-0004
To be published on 2019-08-15 by SAE International in United States
In the development processes for an engine control scheme and a novel engine configuration, 1D or 0D engine cycle simulation is effective and has been widely utilized, in these years. In SI engines, engine operations with the highly lean air-fuel mixture or highly diluted with EGR gas have been known as one of the most effective strategies to save fuel consumption. Following these situations, it is strongly demanded to develop a predictive combustion model capable of accurately predicting the effects of air-fuel ratio and EGR ratio on combustion characteristics, and thus on engine performance. In this paper, to predict highly lean or EGR diluted combustion with enough accuracy in 1D/0D engine simulation, a spark ignition model capable of predicting spark discharge circuit and a spark discharge channel behavior in the cylinder, and a flamelet concept model were applied into a single cylinder engine performance prediction model. In this paper, to predict highly lean or EGR diluted combustion with enough accuracy in 1D/0D engine simulation, a spark ignition model capable of predicting spark discharge circuit and…

Performance and emissions of an advanced multi-cylinder SI engine operating in ultra-lean conditions

Renault SA-Cédric LIBERT
University of Naples “Federico II”-Fabio Bozza, Daniela Tufano, Enrica Malfi, Luigi Teodosio, Vincenzo De Bellis
  • Technical Paper
  • 2019-24-0075
To be published on 2019-08-15 by SAE International in United States
Along the design process of a new engine, the calibration phase at the test bench usually involves a relevant percentage of the overall time-to-market. Each control variable, in fact, needs to be properly selected to optimize the performance and emissions, complying with thermal and mechanical stresses limits of the engine. This issue is still more critical for advanced engine architectures, which include additional control variables, such as valve phasing, turbocharger control, EGR level, etc. The aim of this work is the development of a numerically performed calibration procedure, applied to a prototype multi-cylinder Spark Ignition (SI) engine, designed to operate at very lean mixtures. To this aim, an active Pre-Chamber ignition system is considered. The required air flow rate is indeed provided by a Low-Pressure (LP) variable geometry turbocharger group, coupled to a high-pressure e-compressor. A Variable Valve Timing (VVT) device is also selected to reduce pumping losses at low load and for knock control at high-load. For the above engine, seven control variables have to be fixed in each operating condition, namely the Air/Fuel…