Fuel Consumption for Gearshifts

Abstract

The thesis work aims to quantify the effects of interesting variables such as engine speed, engine torque, vehicle mass, rear axle ratio, vehicle speed and road inclination on a gearshift event regarding fuel consumption and transport time. The cost of a gearshift is determined for gearshift between gear 11 and 12 in a AMT overdrive transmission. Firstly, the cost was calculated using simulations that are carried out in the Global simulation platform (GSP) by creating a DOE based simulation matrix where all the above mentioned interesting variablesare varied. The results obtained from these simulations are formulated in the form of thumb rules for the cost of a gearshift in terms of interesting variables. These thumb rules will be used to further develop better gear shifting strategies and also to develop further fuel-saving functions. Secondly, testing on trucks was carried out to measure/estimate the cost of a gearshift. This was done to verify the obtained results from GSP simulations. Since time and resources were limited, the truck test is performed only on certain cases of simulation matrix which were available at the test facility. During truck testing the drive cycle called Borås-Landvetter-Borås cycle is used as this is the most suitable drive cycle which has long stretches of constant road inclination suitable for performing a gearshift at various cruising speeds as that was a requirement