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Trends towards lower vehicle fuel consumption and smaller environmental impact will increase the share of Diesel hybrids and Diesel Range Extended Vehicles (REV). Because of the Diesel engine presence and the ever tightening soot particle emissions, these vehicles will still require soot particle emissions control systems. Ceramic wall-flow monoliths are currently the key players in the Diesel Particulate Filter (DPF) market, offering certain advantages compared to other DPF technologies such as the metal based DPFs. The latter had, in the past, issues with respect to filtration efficiency, available filtration area and, sometimes, their manufacturing cost, the latter factor making them less attractive for most of the conventional Diesel engine powered vehicles. Nevertheless, metal substrate DPFs may find a better position in vehicles like Diesel hybrids and REVs in which high instant power consumption is readily offered enabling electrical filter regeneration.

This paper describes a method for optimization of engine settings in view of best total cost of operation fluids. Under specific legal NOX tailpipe emissions requirements the engine out NOX can be matched to the current achievable SCR NOX conversion efficiency. In view of a heavy duty long haul truck application various specific engine operation modes are defined. A heavy duty diesel engine was calibrated for all operation modes in an engine test cell. The characteristics of engine operation are demonstrated in different transient test cycles. Optimum engine operation mode (EOM) selection strategies between individual engine operation modes are discussed in view of legal test cycles and real world driving cycles which have been derived from on-road tests.

The present contribution gives an overview of the use of different simulation tools for the optimization of injection parameters of a diesel engine. With a one-dimensional tool, the behavior of the mechanics and fluid dynamics of the entire injection system is calculated. This simulation provides information on the dynamic needle lift, injection rates, pressures, etc. The flow within the injector is simulated using a three-dimensional CFD tool. By use of a two-phase model, it is possible to analyze the cavitating flow inside the injector and to calculate the effective nozzle hole area as well as the exit flow characteristics. Mixture formation, combustion and pollutant formation simulation is performed adopting three-dimensional CFD. In order to provide the initial and boundary conditions for the engine CFD simulation and to optimize the engine cycle performance a one-dimensional tool is adopted.

In order to improve the accuracy of vehicle simulation under transient cycle conditions and thus predict performance and fuel consumption, consideration of the complete system engine/drivetrain/vehicle is necessary. The coupling of otherwise independent simulation programs is therefore necessary for the vehicle and engine. The description of thermally transient processes enables the calculation of the heat balance of the engine, which in turn enables the simulation of warming up operation. Through consideration of the engine warming up process, the quality of the prediction of fuel consumption and emissions is improved. The combination of the simulation programs CRUISE and BOOST to determine the engine heat balance has proven to be successful for the analysis of transient drive cycles.

As an alternative to the element based methods, recently a wave based technique (WBT) has been developed. Since it is based on the indirect Trefftz approach, exact solutions of the governing differential equation are used to approximate the dynamic field variables. This paper discusses the extensions of the WBT for the analysis of engine noise radiation problems in 3 dimensions under anechoic conditions. Furthermore, necessary extensions of shape functions, numerical integration and a methodology to create a WBT radiation models are described. The performance of the method compared to a commercial BEM solution is demonstrated with a real engine example.

Increasing powertrain complexity and the growing number of vehicle variants are putting a strain on current calibration development processes. This is particularly challenging for vehicle drivability calibration, which is traditionally completed late in the development cycle, only after mature vehicle hardware is available. Model-based calibration enables a shift in development tasks from the real world to the virtual world, allowing for increased system robustness while reducing development costs and time. A unique approach for drivability calibration was developed by incorporating drivability analysis software with online optimization software into a virtual engine test cell environment. Real-time, physics-based engine and vehicle simulation models were coupled with real engine controller hardware and software to execute automated drivability calibration within this environment.

Exhaust emission legislation world-wide have a common trend towards very low limits, measured for compliance in transient cycles specific for the United States, Japan and Europe. The emission development strategy is focussing on lowest engine-out emissions to require a minimum of exhaust gas aftertreatment. The base engine concept is described and test results, complying with Euro 4, are shown. The emission reduction development for future regulations requires exhaust gas aftertreatment, test results are shown for US 2007, JNLTR and Euro 5. With exhaust gas aftertreatment, discussed in the appendix, the engine development is faced with a big challenge to ensure the minimum exhaust gas temperature required for their proper function.

The world of automotive engineering shows a clear direction for upcoming development trends. Stringent fleet average fuel consumption targets and CO2 penalties as well as rising fuel prices and the consumer demand to lower operating costs increases the engineering efforts to optimize fuel economy. Passenger car engines have the benefit of higher degree of technology which can be utilized to reach the challenging targets. Variable valve timing, downsizing and turbo charging, direct gasoline injection, highly sophisticated operating strategies and even more electrification are already common technologies in the automotive industry but can not be directly carried over into a motorcycle application. The major differences like very small packaging space, higher rated speeds, higher power density in combination with lower production numbers and product costs do not allow implementation such high of degree of advanced technology into small-engine applications.

The well-to-wheel CO2 emissions and energy use of internal combustion engines (diesel and gasoline) are compared to fuel cell automotive propulsion systems. The fuel cell technologies investigated are polymer electrolyte fuel cell (PEFC), alkaline fuel cell (AFC) and solid oxide fuel cell (SOFC). The fuels are assumed to be produced from either crude oil or natural gas. The comparison is based on driving cycle simulations of a mid-class passenger car with an inertia test weight of 1350 kg. The study shows that the optimized diesel drive train (downsized mated to an integrated starter generator) achieves the best overall energy efficiency. The lowest CO2 emissions are produced by compressed natural gas (CNG) vehicles. Fuel cell propulsion systems achieve similar or even better CO2 emission values under hot start conditions but suffer from high energy input required during warm-up.

The regulation of particle number (PN) has been introduced in the Euro 5/6 light-duty vehicle legislation, as a result of the light duty inter-laboratory exercise of the Particle Measurement Program (PMP). The heavy-duty inter-laboratory exercise investigates whether the same or a similar procedure can be applied to the heavy-duty regulation. In the heavy-duty exercise two "golden" PN systems sample simultaneously; the first from the full dilution tunnel and the second from the partial flow system. One of the targets of the exercise is to compare the PN results from the two systems. In this study we follow a different approach: We use a PMP compliant system at different positions (full flow, partial flow and tailpipe) and we compare its emissions with a "reference" system always sampling from the full flow dilution tunnel.

Combustion of premixed stoichiometric charge is free of soot particle formation. Consequently, the development of direct injection (DI) spark ignition (SI) engines aims at providing premixed charge to avoid or minimize soot formation in order to meet particle emissions targets. Engine development methods not only need precise engine-out particle measurement instrumentation but also sensors and measurement techniques which enable identification of in-cylinder soot formation sources under all relevant engine test conditions. Such identification is made possible by recording flame radiation signals and with analysis of such signals for premixed and diffusion flame signatures. This paper presents measurement techniques and analysis methods under normal engine and vehicle test procedures to minimize sooting combustion modes in transient engine operation.

Partial flow sampling methods in emissions testing are interesting and preferred because of their lower cost, smaller size and applicability to engines of all sizes. However the agreement of the results obtained with instruments based on this method to those obtained with the traditional, large tunnel full flow sampling systems needs to be achieved, and the factors of construction that influence this agreement must be understood. These issues have received more attention lately in connection with ISO and WHDC standardization efforts underway to achieve a world-wide harmony in the sampling methods for heavy duty diesel engines, and with the introduction of similar Bag-minidiluter techniques into light duty SULEV gaseous pollutant measurement. This paper presents the theory and practice of a partial flow probe and tunnel design that addresses and minimizes the undesirable effects of the necessary differences between the two sampling methods.

The characteristically good fuel economy of the high speed direct injection diesel engine has led to increased market share as the power unit of passenger cars. This trend is particularly true in Europe and, if not halted prematurely by emissions legislation, is likely to continue. However, another characteristic of the high speed DI engine is increased noise and vibration over its gasoline counterpart. This has meant that additional noise and vibration measures are required in order to approach the competitive refinement levels of gasoline engine installations. This paper considers some of the characteristic diesel engine noise and vibration problems associated with vehicle installation and passenger comfort. The paper also discusses subjective and objective assessment and considers approaches to engineering more desirable sound quality.

Different particulate mass (PM) portable emission measurement systems (PEMS) were evaluated in the lab with three heavy-duty diesel engines which cover a wide range of particle emission levels. For the two engines without Diesel Particulate Filters (DPF) the proportional partial flow dilution systems SPC-472, OBS-TRPM, and micro-PSS measured 15% lower PM than the full dilution tunnel (CVS). The micro soot sensor (MSS), which measures soot in real time, measured 35% lower. For the DPF-equipped engine, where the emissions were in the order of 2 mg/kWh, the systems had differences from the CVS higher than 50%. For on-board testing a real-time sensor is necessary to convert the gravimetric (filter)-based PM to second-by-second mass emissions. The detection limit of the sensor, the particle property it measures (e.g., number, surface area or mass, volatiles or non-volatiles) and its calibration affect the estimated real-time mass emissions.

An optical sensor system provides access to standard SI engine combustion chambers via the cylinder head gasket. Flame radiation within the plane of the gasket is observed with optical fibers which are arranged to allow the tomographic reconstruction of flame distribution. The effect of convective in-cylinder air motion generated by variations of inlet ports and combustion chamber geometries on flame propagation is directly visible. A high degree of correlation between flame intensity distribution and NOx emission levels yields a useful assessment of combustion chamber configurations with minimum emission levels. The location of knock centers is identified.

In relation to further tightening of the emissions legislation for on-road heavy duty Diesel engines, the future potential of cooled exhaust gas recirculation (EGR) as a result of developments in the cooling systems of such engines has been evaluated. Four basic engine concepts were investigated: an engine with SCR exhaust gas aftertreatment for control of the nitrogen oxides (NOx), an engine with cooled EGR and particulate (PM) filtration, an engine with low pressure EGR and PM filtration and an engine with two stage low temperature cooled EGR also with a particulate filter. A 10.5 litre engine was calibrated and tested under conditions representative for each concept, such that 1.7 g/kWh (1.3 g/bhp-hr) NOx could be achieved over the ESC and ETC. This corresponds to emissions 15% below the Euro 5 legislation level.

Emission standards as proposed in Europe and the United States for heavy duty diesel engines will require a NOx and particulate reduction of more than 90%. This cannot be achieved by internal engine measures alone. Aftertreatment systems, for either one or both emission components, plus sophisticated electronic control strategies will be required. Various strategies to comply with EU 4, 5 and US 2007 are discussed, also showing their impact on engine performance. For typical 1 and 2 liter per cylinder engines, emission reduction concepts are assessed to identify the most suitable technology for major worldwide markets. The assessment is based on thermodynamic studies, test-bed results and estimates on cost and infrastructure implications.

A series of experimental studies of diesel spray and combustion characteristics was carried out using circular, elliptic and step orifices. The experiment was performed on a 3-litre single-cylinder engine with optical access. In the engine tests, an elliptic-orifice nozzle with an aspect ratio of approximately 2:1, and a step-orifice nozzle were compared with circular-orifice nozzles. All orifices had sharp-edged inlets. The nozzles were tested at injection pressures extending from 300 to 1300 bar. The nozzles were evaluated in respect of initial spray tip velocity, penetration, spray cone angle, spray width, intermittency and heat-release. Substantial differences were observed in the spray characteristics: At an injection pressure of 300 bar, the spray width increased twice as fast in the minor axis plane of the elliptic orifice and step orifice than the circular orifices.

Future limits on emissions for both gasoline and Diesel engines require adequate and advanced systems for the after-treatment of the exhaust gas. Computer models as a complementary tool to experimental investigations are an indispensable part to design reliable after-treatment devices such as catalytic converters and Diesel particulate filters including their influence on the power-train. Therefore, the objective of this contribution is to present an integrated 1D to 3D simulation workflow of of catalytic converters and Diesel particulate filters. The novelty of this approach is that parameters or set of parameters, obtained by a fast and efficient 1D-gas exchange and cycle simulation code for power-trains (AVL (2002a)), are readily transferable onto a 3D general purpose simulation code (AVL (2002b)). Thus, detailed aspects such as spatial distribution of temperatures or heat losses are investigated with only a single effort to estimate parameters.

Best fuel efficiency is one of the core requirements for commercial vehicles in India. Consequently it is a central challenge for commercial vehicle OEMs to optimize the entire powertrain, hence match engine, transmission and rear axle specifications best to the defined application. The very specific real world driving conditions in India (e.g. traffic situations, road conditions, driver behavior, etc.) and the large number of possible commercial powertrain combinations request an efficient and effective development methodology. This paper presents a methodology and tool chain to specify and develop commercial powertrains in a most efficient and effective way. The methodology is based on the measurement of real world driving scenarios, identification of representative Real World Driving Profiles and vehicle system simulation which allows extended analysis of the road topography, the traffic situation as well as the driver behavior.