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Improved Fuel Metering for Port Fuel Injection by Controlled Valve Operation
Abstract:
Engine management systems combined with fuel injectors allow a precise fuel metering for a robust combustion process. Stricter emission legislations increase the requirements for these port fuel injection systems (PFI), whereas the price is still the main driver in the emerging low cost 2-wheeler market. Therefore, a holistic mechatronic approach is developed by Bosch, which allows an improved fuel metering over life time and furthermore provides new possibilities for diagnosis without changing the injector itself.
This example of an intelligent software solution provides the possibility to further improve the accuracy of the fuel metering of an injector. By use of the information contained in the actuation voltage and current, the opening and closing times of the injector are derivable. The present paper illustrates how these features can be used to extend the dynamic flow range of injectors (minimum amount of fuel compared to the maximum amount of fuel) and how the deviations from injector to injector can be reduced. In order to improve the robustness of the system regarding varying operating conditions (battery voltage, pressure, temperature…), an adaptation algorithm is introduced. This adaptation algorithm reduces air fuel ratio deviations in dynamics and by that the emissions, which cannot be directly reduced by an oxygen sensor. Besides the possible reduction of emissions, cylinder imbalances can be compensated and thereby the engine smoothness especially in idling is improved. In addition to the potential analysis, new possibilities for upcoming system trends are discussed.