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The proposed paper deals with the development process and initial measurement results of an opposed-piston combustion engine for application in a Free-Piston Linear Generator (FPLG). The FPLG, which is being developed at the German Aerospace Center (DLR), is an innovative internal combustion engine for a fuel based electrical power supply. With its arrangement, the pistons freely oscillate between the compression chamber of the combustion unit and a gas spring with no mechanical coupling like a crank shaft. Linear alternators convert the kinetic energy of the moving pistons into electric energy. The virtual development of the novel combustion system is divided into two stages: On the one hand, the combustion system including e.g. a cylinder liner, pistons, cooling and lubrication concepts has to be developed.

The present paper deals with the experimental investigation of homogeneous charge compression ignition in a free-oscillating two-stroke free-piston engine. The Free Piston Linear Generator (FPLG), which is being developed at the German Aerospace Center (DLR), is an innovative internal combustion engine for the generation of electrical power. This concept can for example be used in hybrid electric vehicles, as an auxiliary power unit or in combined heat and power units. The FPLG consists of three main components. In the two-stroke combustion unit, heat is released by burning a fuel-air mixture and a piston is accelerated. This energy is then converted into electric energy in the second component, the linear generator. This subsystem consists of electromagnetic coils as a stator and permanent magnets as a mover. The mover is rigidly coupled to the combustion piston.

The present paper introduces the Free Piston Linear Generator (FPLG) - a compact electricity generation unit, which is being developed at the German Aerospace Center (DLR). It is designed as a free-piston combustion engine with integrated linear generator. This combination allows for highly efficient conversion of the chemical energy stored in a fuel to electrical energy. By combining a two stroke combustion chamber, a linear alternator and an adjustable gas spring the engine design results in a compact package. In comparison to conventional combustion engines, additional degrees of freedom are available for controlling the combustion process. In this context efficiency advantages are expected due to the missing mechanical link to a crank which leads to flexibility in terms of stroke and compression ratio. Applied as a range-extender-unit, the system provides additional electric energy to electric vehicles in case of discharged batteries.

The need to reduce weight of large and heavy components used by the automotive and aerospace industries such as engine block, cylinder head cover and helicopter gearbox housing has led to the development of new Mg gravity casting alloys that provide adequate properties and cost effective solution. The new Mg gravity casting alloys are designed for high stressed components that operate at a temperature up to 300°C. These new alloys exhibit excellent mechanical properties and creep resistance in T-6 conditions. The present paper aims at introducing three new Mg gravity casting alloys designated MRI 201S, MRI 202S and MRI 203S, which were recently developed by the Magnesium Research Institute of DSM and VW. Apart from the excellent high temperature performance of these alloys, they provide adequate castability and dimension stability along with good weldability and corrosion resistance.

Recently several new magnesium alloys for high temperature applications have been developed with the aim to obtain an optimal combination of die castability, creep resistance, mechanical properties, corrosion performance and affordable cost. Unfortunately, it is very difficult to achieve an adequate combination of properties and in fact, most of the new alloys can only partially meet the required performance and cost. This paper aims at evaluating the current status of the newly developed alloys for powertrain applications. The paper also addresses the complexity of magnesium alloy development and illustrates the effect of alloying elements on properties and cost. In addition, the paper presents an attempt to set the position of each alloy in the integrated space of combined properties and cost