SAE International The Fuel Efficiency Improvement through a Six Speed Manual Transmission Application in Passengers Vehicles with Low Displacement Engines 2011-01-1430

The objective of this paper is to share the benefits regarding a study of fuel economy improvements involving Powertrain technologies. In this case our research was concentrated in vehicles transmissions initiatives like a Six Speed Manual Transmission application in Passengers Vehicles with low displacement engines. During the last 10 years the fuel economy challenges has presented a significant growth mainly due to two simple factors. First of all the fuel price which is the main driver to keep this technological continuous improvement. This fact has a direct influence in customers satisfaction, so all car makers concentrate huge efforts to provide intelligent solutions in order to increase competitiveness, as for example, the flex fuel engines ( Figure 1 ). In parallel, the "green" appeal raises everyday stronger. Therefore the air pollution caused by vehicles gas emissions reinforces this commitment. So low displacement engines are the key to achieve these targets however it brings many limitations like short transmission ratios as consequence of low torque capacity. Base on such assumptions, it's fundamental to maximize the torque usage provided by the engine which is managed through a mechanical transmission. So the gears ratios selection is an important technique to explore alternatives to get the best torque usage for a defined engine torque curve.