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Due to the contradiction of the market demands and legal issues OEMs are forced to invest in finding concepts that assure high fuel economy, low exhaust emissions and high specific power at the same time. Since mechanical losses may amount up to 10 % of the fuel energy, a key to realise such customer/government specific demands is the improvement of the mechanical performance of the engines, which comprises mainly friction decrease and lightweight design of the engine parts. In order to achieve the mentioned objectives, it has to be checked carefully for each component whether the design potentials are utilized. Many experimental studies show that there is still room for optimization of the cranktrain parts, especially for the crankshaft. A total exploitation of the crankshaft potentials is only possible with advanced calculation approaches that ensure the component layout within design limits.

The main assignment of Controlled Auto Ignition (CAI) operation range expansion is to reduce the burn rate or combustion noise at high load and to minimize misfire at low load. The potential of two principal EGR strategies is well known to initiate CAI in a wide range of operation map by using a variable train system: the Exhaust Port Recirculation (EPR) for higher part load and the Combustion Chamber Recirculation (CCR - also called Negative Valve Overlap) for lower part load. However the detailed comparison of the ignition phenomena with each EGR strategy has not been fully studied yet. In this paper, EPR and CCR were compared with same operational condition (engine speed and load). For the analysis, flame luminescence and Raman scattering method for optical measurement and STAR-CD (CD-adapco) for numerical simulation are used.

In the last few years the requirement to optimize powertrain noise and vibration has increased significantly. This was caused by the demand to fulfill the vehicle's exterior noise legislative limits in Europe, and by increased customer awareness for high ride comfort. Much effort concentrated on the engine and the powertrain as prime sources of noise and vibration in a vehicle. The cranktrain with its moving components is a significant source of noise and vibration excitation within the engine. This paper describes results of investigations to evaluate various design alternatives in respect to NVH. The influences of crankshaft material, of balancing rate and of secondary shaking forces are discussed, with the aim to evaluate these various design options.

This paper reports the results of theoretical and experimental investigations in the field of variable intake - valve control of spark-ignition engines. Different degrees of freedom for a variable intake profile such as variable intake opening and closing events, variable valve lift, as well as the deactivation of one of the intake valves per cylinder of a multi-valve engine are considered and evaluated concerning their potential to reduce pumping losses, to support mixture formation, and to improve combustion. The investigations show that additional efforts are necessary to convert the potential of minimized pumping losses due to unthrottled SI-engine load control into reduced fuel consumption and good driveability. Increased gas velocities during intake for low engine speed and load and adjusted residual-gas fractions according to the different operating conditions prove to be very efficient parameters to improve engine performance under unthrottled conditions.

Sound design of vehicle interior and exterior noise is becoming more and more important for the customer's impression of product quality. To accommodate for this, FEV has developed a sound design method that utilizes FEV VINS (Vehicle Interior Noise Simulation) to design series production relevant hardware modifications. Within a new internal research program, FEV's NVH specialists investigated the theory of musical harmonics and compared the results with engine acoustics in an effort to establish if and what mechanical acoustics can learn from musical harmonics. Looking at engine acoustics from the point of view of musical harmonic theory, the specific combination of half and integer engine orders in particular offers the possibility of creating harmonious noise content. Furthermore, we can estimate how the typical subjective evaluations derive from the integer and half engine orders that occur depending on the engine concept.

The electrification of vehicle propulsion has caused a significant change in many areas including the world of vehicle acoustics. Comments from the media currently range from “silently hums the future” to “electric car roars with V8 sound”. Decades of experience in designing brand-specific vehicle sound based on noise and vibration generated by combustion engines cannot be simply transferred to the upcoming vehicles driven purely by electric powertrains. Although electric vehicles are almost always considerably quieter than those powered by internal combustion engines, the interior noise is characterized by high-frequency noise components which can be subjectively perceived as annoying and unpleasant. Moreover, such disturbing noise is no longer masked by combustion engine noise. Fundamental questions regarding the sound design of electric vehicles have yet to be answered: it remains unclear what exactly the interior noise of an electric vehicle should sound like.

All reciprocating engines from the first Diesel engine to turbocharged formula 1 engines require a sealing of the combustion chamber. This sealing is realized by the compression rings. Today a set of two compression rings and one oil control ring is standard, the large variety of available solution demonstrate the continuous effort and attention paid to an optimized system performance since the first engine was started. The complexity of the interactions with the mechanical, thermal, thermodynamic, tribologic, dynamic behavior of the piston still requires mechanical testing of the various components before release to series production. This procedure can be shortened by use of simulation models reflecting the real behavior in detail to select the most promising combinations of components and characteristics.

Geartrain-related noise has become a more dominant noise concern mainly due to the increasing demand for high-pressure injection systems. Engine geartrain noise is mainly caused by torque fluctuations of the crankshaft and the injection system, both leading to tooth impacts between the gears of the geartrain. Gear impacts can generate dominant NVH problems due to the high frequency content of the gear impact forces, although their amplitudes are much lower than those of the combustion forces. If the natural frequencies of the surrounding structure are met, an intensive radiation of the surrounding structure is caused. FEV has developed a simulation method for the analysis of geartrain dynamics aimed at identifying and optimizing potential noise sources. This simulation method is an essential tool for the development process of a technical product. It realizes a minimum effort to set up the model at reduced calculation time.

The IDI diesel engine still offers a substantial development potential. One major advantage is its low fuel consumption and, hence, its low CO2 emission compared to gasoline engines. The disadvantage of its higher noise emission, however, requires particular attention in the development stage. By means of modern signal analysing and signal processing methods in combination with computer simulation methods new tools for the development of low noise Diesel engines are available. The noise emission of IDI diesel engines has on average been reduced by about 5 to 8 dBA within the last 15 years. This trend will continue further despite the introduction of more and more light weight design components. Today's IDI diesel engine is mainly dominated by high noise levels in the frequency range about 1600 to 2000 Hz. In-depth measurements show that this is generally caused by a high combustion excitation (Helmholtz-resonance) and, in addition, structure weaknesses of the crankcase.

At the present time, combustion process effects on vehicle interior noise can be evaluated only when vehicle and engine are physically available. This Paper deals with a new method for the prediction of combustion process induced vehicle interior noise. The method can be applied already in early combustion system development and allows a time and cost efficient calibration optimization of engine and vehicle. After establishing appropriate transfer weighting functions (engine) and structure transfer functions (vehicle), audible vehicle interior noise is generated based on appropriate cylinder pressure analysis. Combustion process effects on interior noise can be judged subjectively as well as objectively. Thus, combustion process development at the thermodynamic test bench is effectively supported to achieve an optimal compromise with respect to fuel consumption, exhaust emission and interior noise quality.

The current direction for Diesel combustion system development is towards homogenization, in order to reduce particulate and NOx emissions. However, a strong increase of carbon monoxide emissions (CO) is frequently noted in combination with enhanced homogenization. Therefore, the current investigation focuses on a detailed analysis of the particulate - CO trade-off using a laser-optical and multidimensional CFD investigation of the combustion process of a swirl HSDI system. The CFD methodology involves reduced kinetics for soot formation and oxidation and a three-step CO model. These models are validated by a detailed comparison to optical measurements of flow, spray penetration and the spatial distribution of soot, temperature and oxygen concentration. The results obtained show that high concentrations of CO occur as an intermediate combustion reaction product. Subsequently, CO and soot are oxidized in large areas of the combustion chamber.

The loads on the plain bearings of modern combustion engines increase continuously. Reasons for this development are increasing engine speeds on gasoline engines, growing cylinder peak pressures at diesel engines and both combined with the steady trend toward light weight concepts. The still significantly increasing power output of modern engines has to be combined with actions reducing the engine friction losses, as for example smaller bearing dimensions or lower engine oil viscosities. At the same time the comfort, lifetime and engine service interval targets are aggravating boundary conditions. This development leads to the point, where former approaches toward plain bearing layout reach their systematic limitations - a first indication are bearing failures, which occur even though all conventional layout criteria's are fulfilled. Further effects need to be considered to simulate the behavior of the plain bearing under the boundary conditions of a fired combustion engine.

Fuel consumption of a modern combustion engine is significantly influenced by the mechanical friction losses. Particularly in typical city driving, the reduction of the engine friction losses offers a remarkable potential in emission and fuel consumption reduction. The analysis of the engine friction distribution of modern engines shows that the piston group has a high share at total engine friction. This offers a high potential to optimize piston group friction. The paper presents results of recent research and development work in the field of the tribological system piston/piston ring/cylinder bore.

Passenger cars with diesel engines have better fuel economy than cars with gasoline engines. Also diesel engines typically have lower HC and CO emissions than all but the very best, state-of-the-art gasoline engines. On the other hand, diesel NOx and particulate emissions are higher, but recent developments have significantly reduced diesel particulate emissions. While the regulated emissions from both engines are well known, there are relatively few data on the non-regulated emissions for modern diesel engines.

The main function of an engine's lubrication system is to supply the different engine components with sufficient oil under all operating conditions. The demand of modern engines regarding the necessary oil pressure and flow of the individual components is influenced by the engine speeds and the accelerations due to the vehicle driving conditions. In addition to that, the lubrication system effects the following topics: The drive power of the oil pump which is influenced by the oil pump capacity, the oil pressure and mechanical losses of the oil pump. The oil mass which is supplied to the engine oil consumers and flows back via the oil return system to the crankcase and the oil pan. In the crankcase ventilation system, oil and gas have to be separated. The oil aeration due to the oil mass in the crankcase and the moving parts. The ventilation losses in the crankcase which are influenced by the axial ventilation areas and the moved oil mass.

Dielectric barrier discharges offer the advantage to excite molecules to reaction processes on a low temperature level in an O2 containing exhaust gas of gasoline or diesel engines. With the aim of a flexible coaxial reactor and a compact and efficient generator the influence of geometric and electric parameters on the reduction of exhaust gas components was determined. Geometric parameters studied were gap width, length, contour of the reactor. Electric parameters were: voltage curve, voltage height, frequency and electric power. Using the advantage of low temperature reactions it was possible to reduce the HC emission of a gasoline engine by about 35% within an electric power of 1000 W.

In the recent past, interior noise quality has developed into a decisive aspect for the evaluation of overall vehicle quality. At most operating points, the dominating interior noise share is generated by the powertrain. Interior noise simulation is a new tool for upgrading interior noise. Based on measurements of air- and structure-borne noise excitations caused by the powertrain, the interior noise shares are determined by applying the properties of the transfer paths. By superimposing the individual interior noise shares, the overall interior noise can be predicted. Well before the engine is operated in the vehicle for the first time, annoying interior noise shares, their causes and their transfer paths can be identified by subjective and objective analysis. This enables the engineer to focus on vital optimization measures as to excitations occurring at the engine as well as to transfer paths in the vehicle.

For the use in flexible fuel vehicles able to operate with mixtures of alcohol fuels and gasoline, an intelligent alcohol sensor has been developed. Based on the measurement of the dielectric constant, this sensor overcomes the problems with optical measuring principles; these problems are due to sensitivity to different contents of aromatics. To increase the accuracy, a microprocessor evaluates the input signals (dielectric constant and other parameters). Thus, a compensation of misdetection due to impurities can also be achieved. The output characteristic of the sensor can be chosen freely; the output voltage can correspond to the alcohol content as well as to the required correction factor for the injection time.

The reduction of particulate emissions from diesel engines is one of the most challenging problems associated with exhaust pollution control, second only to the control of NOx from any “lean burn” application. Particulate emissions can be controlled by adjustments to the combustion parameters of a diesel engine but these measures normally result in increased emissions of oxides of nitrogen. Diesel particulate filters (DPFs) hold out the prospect of substantially reducing regulated particulate emissions and the task of actually removing the particles from the exhaust gas has been solved by the development of effective filtration materials. The question of the reliable regeneration of these filters in situ, however, remains a difficult hurdle. Many of the solutions proposed to date suffer from high engineering complexity and/or high energy demand. In addition some have special disadvantages under certain operating conditions.

Fuel additives can contribute to maintaining the performance of diesel engines in a variety of ways. This holds true for current and future engine technology. Fouling of indirect injection engines (IDI) has been studied at length. Fouling of direct injection engines (Dl) is less known and less well understood. Problems associated with Dl fouling and a proposed mechanism for it are discussed. Additive effectiveness in preventing injector fouling is confirmed. Injector hole corrosion/erosion, as experienced in the Cummins N14 engine, can be avoided by the appropriate additive chemistry. Particulate traps can also benefit from ashless additive technology aimed at increasing the time between regeneration steps, hence improving effective trap life.