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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.

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.