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Partly competing objectives, as low fuel consumption, low friction, long oil maintenance rate, and at the same time lowest exhaust emissions have to be fulfilled. Diminishing resources, continuously reduced development periods, and shortened product cycles yield detailed knowledge about oil consumption mechanisms in combustion engines to be essential. There are different ways for the lubricating oil to enter the combustion chamber: for example as blow-by gas, leakage past valve stem seals, piston rings (reverse blow-by) and evaporation from the cylinder liner wall and the combustion chamber. For a further reduction of oil consumption the investigation of these mechanisms has become more and more important. In this paper the influence of the mixture formation and the resulting fuel content in the cylinder liner wall film on the lubricant oil emission was examined.

The steady increase of engine power and the demand of lightweight design along with enhanced reliability require an optimized dimensioning process, especially in cylinder head valve bridge, which is progressively prone to cracking. The problems leading to valve bridge cracking are high temperatures and temperature gradients on one hand and high mechanical restraining on the other hand. The accurate temperature estimation at the valve bridge center has significant outcomes for valve bridge thickness and width optimization. This paper presents a 1D heat transfer model, which is constructed through the cross section of the valve bridge center by the use of well known quasi-stationary heat convection and conduction equations and reduced from 3D to 1D via regression and empirical weighting coefficients. Several diesel engine cylinder heads with different application types and materials are used for model setup and verification.

Torque and performance requirements of Diesel engines are continually increasing while lower emissions and fuel consumption are demanded, thus increasing thermal and mechanical loads of the main components. The level of peak firing pressure is approaching 200 bar (even higher in Heavy Duty Diesel engines), consequently, a structural optimization of crankcase, crank train components and in particular of the cylinder head is required to cope with the increasing demands. This report discusses design features of cylinder head concepts which have the capability for increasing thermal and mechanical loads in modern Diesel engines

Based on the TurboDISI engine presented earlier [1], [2], a new Spray Guided Turbo (SGT) concept with enhanced engine performance was developed. The turbocharged engine was modified towards utilizing a spray-guided combustion system with a central piezo injector location. Higher specific power and torque levels were achieved by applying specific design and cooling solutions. The engine was developed utilizing a state-of-the-art newly developed charge motion design (CMD) process in combination with single cylinder investigations. The engine control unit has a modular basis and is realized using rapid prototyping hardware. Additional fuel consumption potentials can be achieved with high load EGR, use of alternative fuels and a hybrid powertrain. The CO2 targets of the EU (120 g/km by 2012 in the NEDC) can be obtained with a mid-size vehicle applying the technologies presented within this paper.

Increased demand for highly fuel efficient propulsion systems drives the engine development community to develop advanced technologies allowing improving the overall thermal efficiency while maintaining low emission levels. In addition to improving the thermal efficiencies of the internal combustion engine itself the developments of fuels that allow improved combustion as well as lower the emissions footprint has intensified recently. This paper will describe the effects of five different fuel types with significantly differing fuel properties on a state-of-the-art light-duty HSDI diesel engine. The fuels cetane number ranges between 26 and 76. These fuels feature significantly differing boiling characteristics as well as heating values. The fuel selection also contains one pure biodiesel (SME - Soy Methyl Ester). This study was conducted in part load and full load operating points using a state of the art HSDI diesel engine.

The main tasks for all future powertrain developments are: regulated emissions, CO2-values, comfort, good drivability, high reliability and affordable costs. One widely discussed approach for fuel consumption improvement within passenger car applications, is to incorporate the downsizing effect. To attain constant engine performance an increase of boost pressure and/or rated speed is mandatory. In both cases, the mass flow rate through the intake and exhaust ports and valves will rise. In this context, the impact of the port layout on the system has to be reassessed. In this paper, the impact of the port layout on a modern diesel combustion system will be discussed and a promising concept shall be described in detail. The investigations shown include flow measurements, PIV measurements of intake flow, CFD simulations of the flow field during intake and results from the thermodynamic test bench. One of the important topics is to prove the impact of the flow quality on the combustion.

Two single-cylinder diesel engines were optimised for advanced combustion performance by means of practical and cumulative hardware enhancements that are likely to be used to meet Euro 5 and 6 emissions limits and beyond. These enhancements included high fuel injection pressures, high EGR levels and charge cooling, increased swirl, and a fixed combustion phasing, providing low engine-out emissions of NOx and PM with engine efficiencies equivalent to today's diesel engines. These combustion conditions approach those of Homogeneous Charge Compression Ignition (HCCI), especially at the lower part-load operating points. Four fuels exhibiting a range of ignition quality, volatility, and aromatics contents were used to evaluate the performance of these hardware enhancements on engine-out emissions, performance, and noise levels.

Six diesel, kerosene, gasoline-like, and naphtha fuels have been tested in a single cylinder diesel engine and a demonstrator vehicle, both equipped with similar engine technology and optimized for advanced combustion performance. This study was completed in order to investigate the potential to reduce engine-out emissions while maintaining engine efficiency and noise levels through changes in both engine hardware and fuel properties. The fuels investigated in this study were selected in order to better understand the effects of ignition quality, volatility, and molecular composition on engine-out emissions and performance. The optimized bench engine used in this study included engine hardware enhancements that are likely to be used to meet Euro 6 emissions limits and beyond, in part by operating under advanced combustion conditions, at least under some speed and load conditions.

The Yuchai F-6113 is an inline 6-cylinder heavy duty Diesel engine, mainly for truck application with a displacement of 8.4 liters and a rated power of 258 kW. It was derived from the F-6108 with a displacement of 7.3 liters. The boundary conditions for the new crankcase were set by the existing machining line. Substantially increasing the bore diameter while keeping the bore pitch constant, was achieved by replacing the conventional top stop liner with a mid stop liner with open deck. This liner concept is rather unique for heavy duty truck engines. The two 2-valve cylinder heads, covering 3 cylinders each, were replaced by a 4-valve one-piece cylinder head. The design comprises an electronically controlled Unit Pump Injection System (UPS) with the alternative to use an inline injection pump. The engine structure was laid out for the high specific output and the peak cylinder pressure requirements for the compliance with Euro III emission legislation.

Beside the traditional prediction of stresses and verification by mechanical testing the optimization of cylinder liner bore distortion is one of today's most important topics in crankcase structure development. Low bore distortion opens up potentials for optimizing the piston group. As the piston rings achieve better sealing characteristics in a low deformation cylinder liner, oil consumption and blow-by are reduced. For unchanged oil consumption and blow-by demands, engine friction and subsequently, fuel consumption could be reduced by decreasing the pre-tension of the piston rings. From the acoustical point of view an optimization of piston-slap noise is often based on an optimized bore distortion behavior. Apart from basics to the behavior of liner bore distortion the paper presents advanced analytical and empirical methods for detailed prediction, verification and optimization of bore distortion taking into account the effective engine operation conditions.

A fuel cell based Auxiliary Power Unit (APU) represents a rather complex technical system consisting of different subsystems, components and low-level controllers. Particularly in the case of gasoline-fueled systems, a sophisticated supervisory control is needed to manage the sequential control and to achieve fault tolerant and fail-safe operation. In this paper, a state machine-based APU control concept is presented, offering a transparent and modular structure. In addition to a superior control system (top level supervisor) that manages the overall strategies and the interaction of all subsystems, each subsystem is equipped with its own subsystem control (second level supervisor). This controller is responsible for all subsystem specific issues. The APU control concept was implemented using Matlab®/Simulink® and applied on a rapid prototyping controller unit.

Due to today's demands to reduce cost and product time to market, engineering procedures are increasingly using more sophisticated simulation techniques, instead of validation testing. Early implementation of CAE methods yield higher quality products, even with first prototypes, reducing the design iterations required to reach production quality. The strategy is to conduct specific evaluations of a realistic representation of the product while focusing on the key boundary conditions necessary to extract fatigue effects. Discussed in this paper are adequate CAE methods for early identification, evaluation and removal of conceptual and local structural weaknesses. Possible solutions gained from a computational optimization process are discussed for highly loaded HSDI diesel cylinder heads as a representative example.

Future HD Diesel engine technology is facing a combination of both extremely low exhaust emission standards (US 2002/2004, EURO IV and later US 2007, EURO V) and new engine test procedures such as the European Transient Cycle (ETC) in Europe and the Not-to-Exceed Area (NTE) in the US). Customers furthermore require increased engine performance, improved efficiency, and long-term durability. In order to achieve all targets simultaneously, future HD Diesel engines must have improved fuel injection and combustion systems and utilize suitable technologies such as exhaust gas recirculation (EGR), variable geometry turbine turbocharger systems (VGT) and exhaust gas after-treatment systems. Future systems require precision controlled EGR in combination with a VGT-turbocharger during transient operation. This will require new strategies and calibration for the Electronic Engine Control Unit (ECU).

Fuel properties are always considered as one of the main factors to diesel engines concerning performance and emission discussions. There are still challenges for researchers to identify the most correlating and non-correlating fuel properties and their effects on engine behavior. Statistical analyses have been applied in this study to derive the most un-correlating properties. In parallel, sensitivity analysis was performed for the fuel properties as well as to the emission and performance of the engine. On one hand, two different analyses were implemented; one with consideration of both, non-aromatic and aromatic fuels, and the other were performed separately for each individual fuel group. The results offer a different influence on each type of analysis. Finally, by considering both methods, most common correlating and non-correlating properties have been derived.

The application of technologies such as direct injection, turbo charging and variable valve timing has caused a significant evolution of the gasoline engine with positive effects on fuel consumption and emissions. The current developments are primarily focused on the realization of improved full load characteristics and fuel consumption reduction with stoichiometric operation, following the downsizing approach in combination with turbo charging and high specific power. The requirements of high specific power in a relatively small cylinder displacement and a wide range of DI injection specifications lead to competing development targets and to a high number of degrees of freedom during engine layout and optimization. One of the major targets is to assess the stability of the combustion system in the early development phase.

The requirement of reducing worldwide CO₂ emissions and engine pollutants are demanding an increased use of bio-fuels. Ethanol with its established production technology can contribute to this goal. However, due to its resistive auto-ignition behavior the use of ethanol-based fuels is limited to the spark-ignited gasoline combustion process. For application to the compression-ignited diesel combustion process advanced ignition systems are required. In general, ethanol offers a significant potential to improve the soot emission behavior of the diesel engine due to its oxygen content and its enhanced evaporation behavior. In this contribution the ignition behavior of ethanol and mixtures with high ethanol content is investigated in combination with advanced ignition systems with ceramic glow-plugs under diesel engine relevant thermodynamic conditions in a high pressure and temperature vessel.

From current point of view future emission legislations for heavy-duty engines as well as industrial engines will require complex engine internal measures in combination with sophisticated aftertreatment systems as well as according control strategies to reach the emission targets. With EU VI, JP 09/NLT and US10 for heavy-duty engines as well as future Tier4 final or stage IV emission legislation for industrial applications, EGR + DPF + SCR probably will be combined for most applications and therefore quite similar technological approaches will be followed up in Europe as well as in the US and in Japan. Most “emerging markets” all over the world follow up the European, US or Japanese emission legislation with a certain time delay. Therefore similar technologies need to be introduced in these markets in the future. On the other hand specific market boundary conditions and requirements have to be considered for the development of tailored system concepts in these markets.

Both, the continuous strengthening of the exhaust emission legislation and the striving for a substantial reduction of carbon dioxide output in the traffic sector depict substantial requirements for the development of future diesel engines. These engines will comprise not only the mandatory diesel oxidation catalyst (DOC) and particulate filter DPF but a NOx aftertreatment system as well - at least for heavier vehicles. The oxidation catalysts as well as currently available NOx aftertreatment technologies, i.e., LNT and SCR, rely on sufficient exhaust gas temperatures to achieve a proper conversion. This is getting more and more critical due to the fact that today's and future measures for CO₂ reduction will result in further decrease of engine-out temperatures. Additionally this development has to be considered in the light of further engine electrification and hybridization scenarios.

Both, the continuous strengthening of the exhaust emission legislation and the striving for a substantial reduction of the carbon dioxide output in the traffic sector depict substantial requirements for the global automotive industry and especially for the engine manufacturers. From the multiplicity of possible approaches and strategies for clear compliance with these demands, engine internal measures offer a large and, eventually more important, very economical potential. For example, the achievements in fuel injection technology are a measure which in the last years has contributed significantly to a notable reduction of the emissions of the modern DI Diesel engines at favorable fuel efficiency. Besides the application of modern fuel injection technology, the linked combustion control (Closed Loop Combustion Control) opens possibilities for a further optimization of the combustion process.