Abstract
Keywords: motorcycle driveline, NVH, judder, tip-in-back-out, idle gear rattle, clonk
A detailed knowledge of vehicle behaviour is a crucial competence of every motorcycle manufacturer. Specialized dynamic simulation environment for motorcycle design and simulation techniques allow the engineers foreseeing the vehicle behaviour under different driving conditions and finding the best setup for drivability, handling and stability. A particular application field which is not yet a standard development approach for motorcycle makers is the dynamical simulation for dimensioning driveline components. Judder vibrations, idle gear rattle, drive gear rattle, "clonks" during the gearshift and other NVH phenomena can compromise the driving comfort up to a reasonable reduction of the vehicle drivability. In some cases dynamic effects of the driveline can cause a great reduction of the durability of driveline components. In a number of design decisions, such uncertainties lead to over-dimensioning of torque transmitting parts and cause unwanted extra weight. These phenomena are often not the result of single element malfunction, but rather of the interaction between the components. For this reason these problems are very hard to foresee early in the development process, prior to building physical prototypes of the complete driveline. This contribution intends to show the concepts developed by BMW-Motorcycle and hofer AG for the evaluation and optimization of the complete driveline of a motorcycle in the virtual environment. Critical load situations e.g. acceleration and deceleration at different loads, gear shifts and alternation of load including hopping, are used to test the behaviour of the virtual driveline. Different solutions and design parameters of the driveline components can be tested in order to find the best configuration for all abovementioned phenomena. This systematic and targeted optimization approach enables the manufacturer to avoid expensive and timeconsuming trial and error loops in the development process.