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Abstract. In modern compression ignited engines, one of the key innovative directions is optimization of the burn process especially to reduce emissions. This optimization can be done by ensuring a better air-fuel mixture. To answer this problem, in the current paper, the authors analysed the vertices formation and velocity inside the combustion chamber in thirteen cases, by using numerical analysis (AVL FIRE Software), to generate pure tumble motion, pure swirl motion, no in-cylinder motion of the air, and other combinations on tumble and swirl motion. The cases that were chosen combine 0%, 50%, 70% and 100% tumble and swirl motion. The greatest velocity of the in-cylinder air motion was noted when a 100%tumble and 50% swirl motion was induced (77.2 m/s at 736 degrees CA), while the smallest velocity was noted at 100% swirl and 0% tumble (71.07 m/s at 736 degrees CA). Because of the different induced motions, the vertices that form inside the combustion chamber have a great influence on air-fuel mixture and implicitly on emissions.

Abstract. The European Commission has been actively involved in the development of the World-wide harmonized Light duty Test Cycle (WLTC). The aim of that project was to develop a harmonized light duty test cycle, that represents the average driving characteristics around the world and to have a legislative world-wideharmonized procedure put in place from 2017 and onwards for determining the level of CO2 emissions. This work presents the results of the effect of automatic and manual transmissions as a drivetrain of a light duty vehicle on WLTC driving cycle. AVL Cruise software was used as simulation platform to analyse the CO2 level and fuel consumption of dynamic vehicle model using different type of drivetrains. At first the simulation tool and the most influential parameters of the driving cycle procedure are described. In the second phase various components and modules for both dynamic models using automatic and manual transmission, as well as the respective input parameters, were defined. Analyses are based on a developed dynamic vehicle model in AVL Cruise. Finally, the simulation results were evaluated and presented for the two dynamic models according to a legislative driving cycle to provide the basis fuel consumption and exhaust gas emissions.

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Abstract. European Union legislation sets mandatory emission and fuel consumption reduction targets for new vehicles and therefore economy remains a key challenge for automotive engineers. Optimizing the transmission shift schedule for an automatic transmission with double clutch is an important part of improving fuel economy. Using simulation and optimization algorithms can ensure that a truly optimal shift schedule is implemented. The main objective of this paper focuses on study the performance of a vehicle with a dual clutch transmission (DCT), with special emphasis on optimizing the shifting schedule using optimization algorithms. In order to study and simulate the shifting strategy the dynamic model is developed based on an existing model in MATLAB Simulink software. In the first phase of the paper a detailed description of the DCT technology, its main functional components and dynamic characteristics are explored. In the second phase model development and simulation concerns the major part of this work, to find the optimal shift schedule for different engine speed and engine torque as it accelerates through the transmission gears by engaging the dual clutches. Finally, the simulation results were evaluated and presented which successfully demonstrate the performance improvement of a dual clutch transmission with an optimized shifting strategy.