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Most major regional automotive markets have stringent legislative targets for vehicle greenhouse gas emissions or fuel economy enforced by fiscal penalties. Large improvements in vehicle efficiency on mandated test cycles have already taken place in some markets through the widespread adoption of technologies such as downsizing or dieselization. There is now increased focus on approaches which give smaller but significant incremental efficiency benefits such as reducing parasitic losses due to engine friction. Fuel economy improvements which achieve this through the development of advanced engine lubricants are very attractive to vehicle manufacturers due to their favorable cost-benefit ratio. For an engine with components which operate predominantly in the hydrodynamic lubrication regime, the most significant lubricant parameter which can be changed to improve the tribological performance of the system is the lubricant viscosity.

Knocking combustion places a major limit on the performance and efficiency of spark ignition engines. Spontaneous ignition of the unburned air-fuel mixture ahead of the flame front leads to a rapid release of energy, which produces pressure waves that cause the engine structure to vibrate at its natural frequencies and produce an audible ‘pinging’ sound. In extreme cases of knock, increased temperatures and pressures in the cylinder can cause severe engine damage. Damage is thought to be caused by thermal strain effects that are directly related to the heat flux. Since it will be the maximum values that are potentially the most damaging, then the heat flux needs to be measured on a cycle-by-cycle basis. Previous work has correlated heat flux with the pressure fluctuations on an average basis, but the work here shows a correlation on a cycle-by-cycle basis. The in-cylinder pressure and surface temperature were measured using a pressure transducer and eroding-type thermocouple.

Rail pressures of modern diesel fuel injection systems have increased significantly over recent years, greatly improving atomisation of the main fuel injection event and air utilisation of the combustion process. Continued improvement in controlling the process of introducing fuel into the cylinder has led to focussing on fluid phenomena related to transient response. High-speed microscopy has been employed to visualise the detailed fluid dynamics around the near nozzle region of an automotive diesel fuel injector, during the opening, closing and post injection events. Complementary computational fluid dynamic (CFD) simulations have been undertaken to elucidate the interaction of the liquid and gas phases during these highly transient events, including an assessment of close-coupled injections.

Most major regional automotive markets have stringent legislative targets for vehicle greenhouse gas emissions or fuel economy enforced by fiscal penalties. Large improvements in vehicle efficiency on mandated test cycles have already taken place in some markets through the widespread adoption of technologies such as downsizing or dieselisation. There is now increased focus on approaches which give smaller, but significant incremental efficiency benefits, such as reducing parasitic losses due to engine friction. The reduction in tail pipe CO2 emissions through the reduction of engine friction using lubricants has been reported by many authors. However, opportunities also exist to reduce the lubricant viscosity during warm up by the thermal management of the lubricant mass.

An optimized monofuel CNG light duty vehicle based on the Opel Zafira was investigated under real-world conditions and the results are presented in this study. To analyze the real-world performance of the monofuel CNG vehicle due to fuel consumption and exhaust emissions representative experimental test on road-test routes were performed, including sections with significantly different driving conditions. Furthermore, driving tests at different constant speeds on freeway were carried out. A benchmarking to the same vehicle with diesel powertrain was done as well. The test vehicles were equipped with a new compact on-board measurement system and additionally GPS tracking to link the received geographic information of the road-test routes with the measured exhaust mass emission data. The measurement results were validated with Matlab Simulink models of the powertrain and vehicle.

The goal of this project was to determine the exhaust mass emissions of light duty trucks (LDT) with three different engine concepts under real world conditions in the urban area of Vienna. Therefore three identical GM Opel Combo LDT with 1.6 liter monovalent CNG S.I. engine, 1.7 liter common rail turbo charged diesel engine and 1.4 liter Ecotec gasoline S.I. engine were tested systematically on representative urban routes and in parcel service. All engines corresponded to the new Euro IV emission standard and were within the same power range.

In this study the performance of a monofuel compressed natural gas articulated truck was investigated under real-world conditions. To analyze the CNG vehicle due to fuel consumption and exhaust emissions a representative road-test route was conducted, including sections with significantly different driving conditions. Moreover, driving tests on freeway under higher load were carried out. As experimental equipment, a new ultra compact on-board system measured the in-car exhaust mass emissions in real time. Every second, a full dataset of CO₂, CO, HC and NOx emission rates was provided. The real-world emission measurements are based on a modal analysis of the emission concentrations in the tailpipe of the vehicle. The exhaust gas mass flow is calculated from the air mass flow and the gas components with a real-time reaction model. In combination with the vehicle speed, the emission rates in g/s are then calculated in gram per kilometer.

The objective of the project was to compare the exhaust gas emissions and fuel consumption of a test vehicle, which was on a one hand operating with premium gasoline 95 RON (RON 95) and a mixture of 90% by volume premium gasoline 95 RON and 10% by volume of high purity bio ethanol (E10) on the other hand. As a test vehicle a Skoda Octavia station wagon was used. The engine of the tested vehicle corresponded to the Euro 4 emission standard. The investigations were conducted under the real world conditions, and also at the chassis dynamometer test bench. The tested vehicle was equipped with a new On-board measurement System (OBM) to determine the mass emissions on real world driving routes. The measurement method is based on modal analysis of the emission concentrations in the tailpipe of the vehicle, and real time exhaust mass flow determination.

This paper focuses on the potentials of a Belt-Starter-Generator (BSG) in the context of an ultra-light vehicle prototype with a target curb weight of only 600 kg. Therefore, two hybrid approaches with a voltage level below 60 V are described and their potentials regarding electrical driving and CO2 reduction are analysed in detail. Introducing the ‘Cars Ultra-Light Technology’ (CULT) project, the holistic lightweight approach is described as a main requirement for the further hybrid investigations. In addition, a P2-hybrid structure with a 12 V BSG on the transmission input shaft enabled unique features despite the low voltage level and limited electrical power resources. The CO2 reduction for this powertrain combination is described and compared to a conventional stop start configuration. The validation process on a dynamic test rig is presented as well.

Future legislations claim further reduction of all restricted emissions as well as the limitation of soot emissions in diesel engines. Special alternative diesel fuels that do not contain aromatic compounds, therefore, promise great potential for further reduction of HC, CO and particulate emissions. During a research project carried out at the Institute for Powertrains and Automotive Technology at the Vienna University of Technology, the potential of alternative diesel fuels was investigated using a state-of-the-art diesel engine with common rail direct injection. The testing took part using an engine test rig as well as on the chassis dynamometer test bench to demonstrate the emission levels in real life conditions. As real biofuel, pure HVO (Hydrogenated Vegetable Oil) was investigated and additionally in different blends with fossil diesel fuel.

In the future, conventional powertrains will increasingly be supplied by sustainable energy sources. Long-haul freight transport requires efficient energy storage and the ability to refuel quickly. For this reason, hydrogen-powered PEM fuel cells are being discussed as a future energy source for long-distance vehicles. However, there are numerous challenges in packaging, system cooling and service life. Above all, the dissipation of the fuel cell’s heat losses places high demands on the design of the cooling system due to the relatively low operating temperature. In the presented study, a complete generic drive train of a long-distance commercial vehicle was set up within a suitable simulation environment to investigate the required sizes of the fuel cell stack, the HV battery, the hydrogen tanks, and the cooling circuit.

The increasing complexity of distributed embedded systems, as found today in airplanes or cars, becomes more and more a critical cost-factor for their development. Model-based approaches have recently demonstrated their potential for both improving and accelerating (software) development processes. Therefore, in the project DECOS1, which aims at improving system architectures and development of distributed safety-critical embedded systems, an integrated, model-driven tool-chain is established, accompanying the system development process from design to deployment. This paper gives an overview of this tool-chain and outlines important design decisions and features.

This work was concerned with study of lubricant introduced directly into the combustion chamber and its effect on pre-ignition and combustion in an optically accessed single-cylinder spark ignition engine. The research engine had been designed to incorporate full bore overhead optical access capable of withstanding peak in-cylinder pressures of up to 150bar. An experiment was designed where a fully formulated synthetic lubricant was deliberately introduced through a specially modified direct fuel injector to target the exhaust area of the bore. Optical imaging was performed via natural light emission, with the events recorded at 6000 frames per second. Two port injected fuels were evaluated including a baseline commercial grade gasoline and low octane gasoline/n-heptane blend. The images revealed the location of deflagration sites consistently initiating from the lubricant itself.

Current commercial vehicles' engines are complex systems with multiple degrees of freedom. In conjunction with current emissions regulations manufacturers are forced to combine highly developed engines with complex aftertreatment systems. A comprehensive simulation model including the engine and aftertreatment system has been set up in order to study and optimize the overall system. The model uses a phenomenological spray combustion model to predict fuel consumption and NO emissions. In addition physical models for the material temperatures and the reaction kinetics were generated for the aftertreatment system. Steady state and transient measurements were used to calibrate the engine as well as the aftertreatment model. The aim for a system-level optimization was a reduction of fuel consumption while meeting emission standards.

In recent years concern has arisen over a new combustion anomaly, which was not commonly associated with naturally aspirated engines. This phenomenon referred to as Low-Speed Pre-Ignition (LSPI), which often leads to potentially damaging peak cylinder pressures, is the most important factor limiting further downsizing and the potential CO2 benefits that it could bring. Previous studies have identified several potential triggers for pre-ignition where engine oil seems to have an important influence. Many studies [1], [2] have reported that detached oil droplets from the piston crevice volume lead to auto-ignition prior to spark ignition. Furthermore, wall wetting and subsequently oil dilution [3] and changes in the oil properties by impinging fuel on the cylinder wall seem to have a significant influence in terms of accumulation and detachment of oil-fuel droplets in the combustion chamber.

In recent years a new combustion phenomenon called Low-Speed Pre-Ignition (LSPI) occurred, which is the most important limiting factor to exploit further downsizing potential due to the associated peak pressures and thus the huge damage potential. In the past there were already several triggers for pre-ignitions identified, whereat engine oil seems to have an important influence. Other studies have reported that detached oil droplets from the piston crevice volume lead to auto-ignition prior to spark ignition. However, wall wetting and subsequently oil dilution and changes in the oil properties by impinging fuel on the cylinder wall seem to have a significant influence in terms of accumulation and detachment of oil-fuel droplets in the combustion chamber. For this reason, the influence of test fuels with different volatility were investigated in order to verify their influence on wall wetting, detachment and pre-ignition tendency.

A naturally aspirated SI engine with port fuel injection was investigated at the Institute for Powertrains and Automotive Technology of the Vienna University of Technology to analyze the impact of the ethanol blend E85 on the full load performance. Measurements and numerical studies with a predictive wall film model have been carried out to explain the mixture cooling, the calorific fluid properties after inlet valve closing and the volumetric efficiency with conventional fuel and E85. It could be shown that only with a detailed modelling of the wall film formation in the inlet port an accurate prediction of the engine's full load performance is possible when studying different fuels with varying fluid properties. Anyway, an integrated approach that includes measurements and numerical investigations is necessary to analyse the mixture preparation and the engine process correctly.

The piston ring and cylinder liner tribosystem is very sensitive. It is a heavily loaded system with high temperature and force exposure. High demands are made on the components in this area. These facts concern not only system components, but also the engine oil which can reach up to 300°C at the inner cylinder walls. High temperatures and force cause oil aging. As a part of the combustion chamber, the piston ring-cylinder liner tribosystem is in close contact with combustion constituents. If alternative fuels like ethanol are used, the influences to this tribosystem have to be investigated. In particular, the impacts of oil aging have to be considered to avoid higher wear and damage to the engine, to assure low fuel consumption, and to extend oil change intervals. Research work on abrasion of the ring-cylinder system was aimed to gain detailed information about the effects on this tribosystem.

One of the limits on the maximum fuel efficiency benefit to be gained from turbocharged, downsized gasoline engines is the occurrence of pre-ignitions at low engine speed. These pre-ignitions may lead to high pressures and extreme knock (megaknock or superknock) which can cause severe engine damage. Though the mechanism leading to megaknock is not completely resolved, pre-ignitions are thought to arise from local autoignition of areas in the cylinder which are rich in low ignition delay “contaminants” such as engine oil and/or heavy ends of gasoline. These contaminants are introduced to the combustion chamber at various points in the engine cycle (e.g. entering from the top land crevice during blow-down or washed from the cylinder walls during DI wall impingement).

The fuel effects on HCCI operation in a spark assisted direct injection gasoline engine are assessed. The low load limit has been extended with a pilot fuel injection during the negative valve overlap (NVO) period. The fuel matrix consists of hydrocarbon fuels and various ethanol blends and a butanol blend, plus fuels with added ignition improvers. The hydrocarbon fuels and the butanol blend do not significantly alter the high or the low limits of operation. The HCCI operation appears to be controlled more by the thermal environment than by the fuel properties. For E85, the engine behavior depends on the extent that the heat release from the pilot injected fuel in the NVO period compensates for the evaporative cooling of the fuel.