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Utilization of direct injection systems is one of the most promising technologies for fuel economy improvement for SI engine powered passenger cars. Engine performance is essentially influenced by the characteristics of the injection equipment. This paper will present CFD analyses of a swirl type GDI injector carried out with the Multiphase Module of AVL's FIRE/SWIFT CFD code. The simulations considered three phases (liquid fuel, fuel vapor, air) and mesh movement. Thus the transient behavior of the injector can be observed. The flow phenomena known from measurement and shown by previous simulation work [2, 7, 10, 11] were reproduced. In particular the simulations shown in this paper could explain the cause for the outstanding atomization characteristics of the swirl type injector, which are caused by cavitation in the nozzle hole.

The basic Semi-Direct-Injection System (SDIS) which is already in production for PWC and applied to small 2-wheeler engines features a low-pressure fuel injection system injecting through the rear scavenge port window in the cylinder symmetry plane onto the piston crown. The patented new SDIS Mk.II System [1] injects through an (additional) scavenge port window that is positioned above the scavenge ports and is controlled by a window in the piston skirt. This new arrangement allows longer injection duration and also other injector positions and directions. A CFD simulation by AVL's FIRE-CFD-code with moving piston and exhaust gas dynamics compares the different injector positions and directions for WOT and rated speed and for a part throttle low speed case. The SDIS Mk.II injection system consists of mass-produced automotive parts thus giving a low cost approach for present 2-stroke engines requiring only moderate engine modifications.

A new hybrid concept is applied to a small carburetted lean burn 2-stroke engine where, according to the underlying patent, the asynchronous motor is mounted on the ICE crankshaft, to provide increased torque during acceleration, lower and stabilise idle speed, replace the electric starter, act as a speed limiter, recover energy during deceleration and to provide the power for the electrically heated catalyst. The paper describes the mechanical development, the redesign of the thermodynamic parts of the donor engine, the light-off optimisation of the electrically heated catalyst, the electric and electronic development including ECU, power electronics, sensors, battery management, mapped ignition system and control strategies. The results show acceleration performance at par of a 50% bigger engine, ULEV level emissions including cold start, and no visible smoke or smell and very low particulate emissions very short after the cold start.