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The inherent drastic reduction of CO2, additionally to the limitation of pollutant emission, but at high level of propulsion power and torque as conditions of customer acceptance, imposes the introduction of new concepts of propulsion generation and management. A drastic reduction of CO2 - as cumulated quantity in the atmosphere - is possible by both reduction of specific energy consumption well-to-wheel for propulsion as well as by the utilization of regenerative fuels, ensuring a significant recycling of CO2 emissions from propulsion systems by photosynthesis. Alternative scenarios to the classical automobile propulsion by piston engine show remarkable potentials in terms of power characteristic, energy consumption or pollutant emissions. On the other hand, the development of internal combustion engines is moving from sophisticated mechanics to modular and adaptable process management.

The similar targets of future spark-ignition (SI) and compression-ignition (CI) engines consisting in the noticeable increase of specific power concomitantly with the drastic reduction of fuel consumption and pollution in a wide operation range lead to similar development of thermodynamic functions and technical solutions. The achieved modular level of implementation of functions and solutions in advanced piston engines allows to establish common development platforms for both SI and CI engines. Such functions are the scavenging management, the spray-guided mixture formation by fuel direct injection, the exhaust gas recirculation and the homogeneous charge compression ignition. Under the technical solutions to their generation there are the super- or turbocharging, the variable control of intake-and exhaust valves and the direct injection techniques by common rails or by high pressure modulation.

The worldwide development of mobility - on air, earth or water - is generally characterized by a trade-off between high power and high torque against low specific energy consumption and low pollutant emission. The achieved diversity of propulsion systems and energy sources for mobility allows to develop advantageous combination scenarios between the utilized energy forms, energy conversion modules, energy storage units on board and propulsion machines. The paper presents the available energy sources and the derivable regenerative fuels, the global CO2 balance for representative propulsion configurations and the specific aspects of the energy storage on board. The most advanced concepts of propulsion - from fuel cells to the hybrid systems are presented in an overview, in relationship with their specific advantages and disadvantages.

The application of supercharging as a measure to improve the engine performances is a basic feature for downsizing concepts applied for advanced automobile engines. The adaptation of such concept to a high speed compact SI engine with a speed range between 2.000rpm and 9.000rpm forms the object of this paper. The determination of the special adapted control strategy as well as the necessary modifications of the basic engine were conducted in this work by mean of simulation with the 1D Code BOOST and coupled modules from 3D simulation by the code FIRE. The used models were generated and calibrated going out from the individual components to be connected: an 1000cc/2 cylinder/4 stroke engine and a screw type compressor. The adaptation of the engine to the supercharging concept, imposed modifications of the valve course and timing as well as of the intake ducts shaping.

The propulsion of future motorcycles and small vehicles will be determined by the reduction of dimensions, weight, fuel consumption and pollutant emission for a considered power output, implicating an improved control of the internal process stages consisting on scavenging, mixture formation and combustion. A main support of such process improvement is the internal mixture formation by gasoline direct injection. However, the compactness and the high-speed range of a small engine for two-wheelers, marine or garden equipment make the application of direct injection more difficult than for automotive engines. On the other hand, after the initially tested wall- and air- guided techniques, it is generally recognized that the only way for a successful large scale utilization of gasoline direct injection is the spray-guided mixture formation.

High power-to-volume ratio and significant reduction of fuel consumption and pollution are paramount development targets for both SI and CI engines for automotive propulsion. Their implementation within a broad function range generated modular technical solutions - as elements of a general down-sizing platform - which are successful applicable in both SI and CI engines. The effects of such techniques, from super-charging or turbocharging, variable valve control and direct injection up to exhaust gas recirculation, autoignition-generated combustion and catalyst system indicate a merging which causes a basic discussion about the convergence of SI and CI engines.

The present and the future legislation norms require increasingly the compliance of strict limits concerning the pollutant emissions of internal combustion engines. According to the usual standards, the measured engine performances are normalized to defined atmospheric conditions. However, the variation of the atmospheric conditions implicates a modification of the thermodynamical and chemical processes during the mixture formation and combustion. The standards take these modifications only indirectly into account in a passive mode without any active correction. The paper presents the results of analysis of the effects of different atmospheric conditions (as pressure, temperature or humidity) on the internal processes of a four-stroke four-valve research engine working with direct injection when using a specially developed integrated sensor for the simultaneous measurement of the atmospheric parameters.

The internal mixture formation by gasoline direct injection offers a remarkable potential to improve the engine performances and to reduce the pollutant emission, due to the large possibilities of process control. On the other hand, the control mechanisms their selves are more complex and sensitive at speed or load variations than the ones used for external mixture formation. The spray characteristics, as well as the shape of injection rate have to be accurately adapted to every condition of load, speed and surrounding. This paper presents a method for the effective optimization of GDI techniques for SI engines, which is exemplified by a system with direct injection by high pressure modulation. The method is based on the interactive optimization of the processes within the injection system respectively during the spray evolution, by a feed-back strategy between separate numerical simulations of both processes.

The worldwide demand for vehicles, respectively for their diversity, corresponding to specific utilizations, increases continuously. On the other hand, the energy resources, the ecological aspects and the traffic flow lead to severe requirements to every new vehicle and propulsion system. Between necessities, specific utilization aspects and requirements, numerous configurations of propulsion systems are conceivable. This paper presents a classification of conventional and advanced propulsion systems and of their combination concepts in base of following criteria: energy resources, ecological aspects, technical feasibility, expected costs. The paper gives an overview of different propulsion systems and of the required energy form - including storage or conversion on board.

The development of advanced techniques for an improved control of scavenging, mixture formation and thereby of the combustion in IC engines is more and more supported by numerical simulation models. However, the benefits in reducing the specific fuel consumption and the pollutant emission are not spectacular. On the other hand, the recent evolution of the fuel cell systems - which let expect a commercial application for automotive propulsion in the next years - demonstrates a remarkable efficiency. There appears a challenge for the IC engines, considering the utilization of similar energetic sources for both systems. This imposes an accelerated optimization of the processes in thermal engines - the central problem being the control of combustion. In this context, the basic models should be reconsidered.

The potential of fuel direct injection regarding the performances of a SI engine is transformable in significant advantages only by an accurate control of the internal air/fuel mixture formation. A main control element is the adaptability of the injection law, respectively of the spray characteristics to the thermodynamic conditions within the combustion chamber for different load and speed. This paper presents a method for the effective implementation of GDI techniques to SI engines, which is exemplified by a system with injection law modulation by pressure. The method is based of the interactive optimization of the processes within the combustion chamber respectively within the injection system, by a feed-back strategy between separate numerical simulations of both systems. For both modules the calibration is ensured by appropriate experimental analysis.

The extremely advantageous power-to-weight, respectively power-to-bulk ratio of two-stroke engines in comparison with four-stroke engines are determining arguments for their further application in light powered two-wheelers. On the other hand, the disadvantages of actual two-stroke engines regarding high pollutant emission, respectively high bsfc - in conditions of the drastic limitation of the pollutant level in the next years - will hinder such applications, if a new quality of the two-stroke process cannot be achieved. As demonstrates in numerous research works, the scavenging improvement of a two-stroke engine can lead to a restricted amelioration of these values, but not to another level. The gasoline direct injection is considered to have the highest potential for such development.

Going from the example of the urban traffic in Europe, where the car use in town areas generally do not exceed 50 km/day, a series hybrid vehicle with light and compact thermal engine as an auxiliary power unit (APU) is demonstrated to be a promising concept. The paper describes such a configuration in base of a developed two-stroke engine with electronically controlled gasoline direct injection. The injection system is characterized by a high-pressure modulation obtained in base of the water hammer effect, which can be accurately adapted for a wide load and speed range of the engine. In this assembly the engine has extremely small dimensions and a dry weight of 8 kg, requiring a place which do not disturb the functions of the basic electric vehicle. The performances are convicting, the CO2 emission being reduced 3 times in comparison with a series four-stroke engine for the same car type, with an autonomy of 340 km and with a maximum speed of 100 km/h.

The hydrocarbon emission of a two-stroke engine can be partially decreased by scavenging improvement, but emission levels of a four-stroke engine can be achieved only by changing the mixture formation concept, specifically excluding the fuel from the scavenging process. Numerous research projects of gasoline direct injection - from liquid injection to air assisted systems - have been concentrated on two-stroke engines, determining the selection of the concepts which are suitable for series applications. This paper presents such a concept, based on the ram tuned injection: The system is characterized by a pressure modulation which can be adapted for an appropriate injection law, determining a suitable mixture formation for an engine with specific features. This electronically controlled injection system has been developed as a compact low cost unit for application to two-stroke engines with swept volumes of 50 cm3 and 125 cm3 which equip the two-wheeled vehicles.

In the application of direct fuel injection to an SI engine the fuel spray characteristics such as droplets velocity and diameter, as well as the penetration length in the combustion chamber - but especially their variation with engine speed and injected quantity - are determining criteria for a mixture formation with the required quality. These characteristics are of particular importance for high speed engines because of the large range of speed variation and become stringent for high speed two-stroke engines where a very short mixture formation time is imposed.

A new Diesel mixture formation process for small high-speed two-stroke engine applications has been developed by the authors. Different injection techniques were applied. A conventional mechanically governed injection system is compared with an electronically controlled ram-tuned fuel injection system. The latter results in more advantageous characteristic values of the engine.