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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.

Particle size distribution and particle number emissions rather than legislated particulate mass emissions from diesel engines are subject of rising concern especially in the US and several Western European countries [1]*. Recently also particle number emissions from gasoline engines attracted much attention since these engines are supposed to emit very high numbers of ultrafine particles or even nano-sized particles [2]. The work described in this paper focused on the impact of modern diesel exhaust gas aftertreatment systems like diesel oxidation catalysts (DOC) and diesel particulate filter (DPF) on particle number emission. Especially the effect that these aftertreatment systems are supposed to significantly increase ultrafine particle numbers (because they may act like “reactors” actively producing ultrafine solid particles) gave reason for investigating the effects and mechanisms more in detail.

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.

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.

Future boundary conditions for vehicle engine development will be very complex since they are “functions” of parameters that are difficult to predict: increasingly stringent legislation, changing consumer demand, and availability of resources. The main development goals for passenger cars today are the enhancement of performance and reduction of fuel consumption and cost while facing future emission standards. In China for example, drastic changes in emission regulation have forced the automotive industry to speed up the development processes and shorten the product life cycles. In this respect, the Mianyang Xinchen Engine Co. Ltd, part of Brilliance Group, Mianyang China and FEV Motorentechnik, Aachen Germany conducted a joint project to study Mianyang's 2.2L, 2-valve, multipoint fuel injection (MPI) gasoline engine.

Reduced resources of mineral oil and growing world energy consumption will increase the demand for alternative energies. Natural gas is gaining interest due to the worldwide ratio of assured reserves of natural gas and crude oil shifting towards natural gas. The main motivation for the use of gas are oil substitution, source diversification and independency of fuel supply as well as the reduction of greenhouse gases especially CO2. Natural gas operation usually reduces the torque of a naturally aspirated engine due to fuel properties. The paper shows that an optimization of a naturally aspirated engine layout can reduce the loss significantly. Besides compression ratio optimization also intake manifold and camshaft redesign for natural gas specific application can reduce the torque loss to a minimum. Super charging or turbo charging of spark ignition engines can effectively overcome the torque loss.

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.

NVH refinement of passenger vehicles is crucial to customer acceptance of contemporary vehicles. This paper describes the vehicle NVH development process, with specific examples from a Diesel sedan application that was derived from gasoline engine-based vehicle architecture. Using an early prototype Diesel vehicle as a starting point, this paper examines the application of a Vehicle Interior Noise Simulation (VINS) technique in the development process. Accordingly, structureborne and airborne noise shares are analyzed in the time-domain under both steady-state and transient test conditions. The results are used to drive countermeasure development to address structureborne and airborne noise refinement. Examples are provided to highlight the refinement process for “Diesel knocking” under idle as well as transient test conditions. Specifically, the application of VINS to understanding the influence of high frequency dynamic stiffness of hydro-mounts on Diesel clatter noise is examined.

Within the PNGV program, very challenging targets in respect to vehicle fuel economy were set. These could not be met with today's gasoline engines and driveline concepts. One possible alternative approach is a hybrid vehicle with a small displacement engine that exceeds the fuel economy of conventional engines: the 1.2L DIATA (Direct-Injection-Aluminum-Throughbolt-Assembly) engine. Within the development of a CIDI engine the NVH aspects are of particular importance as the customer (i.e., driver) should not notice any negative difference to gasoline engines. Therefore, gasoline engine transparency in respect to NVH was one primary goal within the development process. This paper describes the implementation of NVH features into the engine design already in the initial concept design phases, and the consequent NVH optimization throughout the development phase.

The NVH optimization is a key issue for the development of future powertrains. This includes the radiated noise in terms of noise level and sound quality as well as the structure-borne noise excitation via the engine mounts. Experience shows that there are generally no single noise relevant components on modern powertrains which dominate the NVH behaviour. In contrast, a good NVH performance can only be achieved if the optimization process includes every single component and excitation. Only the combination of these optimized designs can lead to a first-class powertrain NVH. Within this paper the NVH optimization process of an existing 4-cylinder in-line spark-ignition powertrain is described. Examples for positive NVH designs are presented and their effect on the NVH behaviour are explained. Combining all positive NVH features into the engine resulted in a noise reduction of 3-5 dBA without any negative effect on fuel economy and performance.

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.