Intake Gas Recycled Valve Modeling of Spark Ignition Engines 2003-01-3721

This work presents the results of an implementation model of an additional valve to the cylinder of an Otto cycle internal combustion engine, to make the engine power modulation possible through recycled of the intake gases, substituting the conventional system in which the modulation is done by the throttle valve. The study was done through simulations on a real engine operating in various conditions, using a computer model elaborated in object oriented programming, based on Object Pascal language. The resulting effects of the valve closing delay on the engine parameters are analyzed, such as volumetric efficiency, compression ratio, torque, specific fuel consumption and thermal efficiency. The study showed the advantages of the proposed system in power modulation, when compared to the conventional throttle valve system. The benefits obtained were greater with partial loads and can be summarized by benefits obtained in specific fuel consumption. At maximum rotation (3600 RPM), the engine modulated by the conventional RGA system presented a reduction in the specific fuel consumption, compared to the conventional engine, that varied from approximately -2.8% (increase in the specific consumption) at full load, up to nearly 53%, at 10% load. With a load of 50%, at this rotation, the consumption reduced in approximately 15%. At 1800 RPM, operating with loads of 10%, 50% and 70%, the reductions reached 38%, 15% and 10% respectively.

All the benefits obtained with the proposed modulation system resulted from a volumetric efficiency improvement, through the elimination of the intake flow strangulation(restrain), imposed by the conventional system throttle valve. The simulations proved that the proposed modulation system leads to significant fuel economy (more than 30%) in partial loads. The impact of this on pollutant emissions and fuel consumption in large scale justifies a greater investment in the study of this proposal.