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With increasing requirements for small engines in terms of functionalities and emission standards, it is essential to be able to offer an integrated full-featured injection system that will meet future requirements. The system described is particularly suitable for small to medium-sized combustion engines, such as power generators, lawnmowers and small motorcycles, and has a corresponding cost structure, compactness and a high degree of integration. The main subject of the development is an electronic fuel injection system, which can provide information about the current air-fuel mixture through model-based software algorithms and also has an integrated ignition coil. This article describes the procedure and the status of the research results of this development project. The basis of the method as already known from similar approaches of stimulating the running engine by a defined feedforward control of the injection quantity.

During the start-up phase of machines it can happen that tools are inadvertently rotating, which is caused by the half-throttle setting. Due to the starting throttle locking mechanism, the engine's rotational speed is above the engagement speed of the tool (for example the chain of a chain saw). This article describes the software algorithms developed by PRUFREX that are able to prevent rotation of the tool upon machine start at idle. The patented software solution is able to differentiate between start behavior with and without a starting throttle locking mechanism based on the machine's speed and time information and, as a result, can identify or estimate the position of the throttle valve. The effect of the algorithms is the switch-over between different ignition curves that are stored in the microcontroller-operated ignition modules. This includes a provision in the start ignition curve that prevents the tool from rotating.