The constantly increasing pressure to reduce CO_2 emissions and naturally also the desireto offer customers a consistently economical concept prompts the automotive industry toutilize gasoline engine combustion even outside the statutory driving cycles. Up to now,development work on the gasoline engine focused primarily on avoiding throttling losses.Parts of these losses are already avoided in VVL-concepts, stratified charge engines ordownsizing strategies. In theory, complete elimination of this share of the losses couldimprove consumption by 30 % at highly throttled operating points. Moreover, furtherpotential is also available in reducing the real gas losses, described by the losses causedby combustion when taking account of real working air composition. These losses arecaused by the isentropic exponent which is changed by pressure, temperature andworking air properties and is thus smaller than κ = 1.4 of the perfect air.A significantly leaner mixture composition can therefore bring the cycle process closer tothe ideal engine. Consistent implementation of this approach results in a concept for agasoline engine where, similar to the diesel engine, load is adjusted by quality controlinstead of throttling. This procedure reduces consumption by up to 28 % in the map and upto 10 % in the driving cycle compared to a current stratified charge concept.This article describes the concept of the "quality-controlled gasoline engine", technicalimplementation and results obtained in simulation and measurements at the engine testbench. The results are then taken to indicate fuel economy potential in driving cycles.It presents solutions for the mixture formulation, charge cycle and combustion process witha view to technical implementation of quality control in the gasoline engine for expandingthe lean combustion limit and for exhaust gas aftertreatment.
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