Abstract
Motorcycles are vehicles regarding which users have extremely strong preferences, so riding comfort determines a large portion of their commercial value. In order to provide the high level of riding comfort sought by motorcycle owners, we must select the most effective settings for the engine and the drive train. This paper concerns fluctuations in longitudinal acceleration when a motorcycle is accelerated, which is one of the benchmarks for evaluating riding comfort. This phenomenon consists of fluctuations in longitudinal acceleration during acceleration that cause an uncomfortable feeling for the rider, so the fluctuations in acceleration must be moderate. In composing the simulation model, we modeled the entire drive train from the crankshaft to the tire into a model. By comparing the results of the simulation model and of field tests, we confirmed that it is possible to simulate fluctuations in the revolutions of the drive train. Based on the results of the simulation, it was possible to posit that fluctuations in the longitudinal acceleration were attributable to play in the dog clutch. We then employed that simulation model to study potential methods for reducing fluctuations in longitudinal acceleration during acceleration. We carried out sensitivity analysis by varying the mechanical properties of the drive train, such as moment of inertia, spring characteristics, and damping characteristics. As a result, we were able to conduct studies on potential improvement methods in various combinations prior to the field tests. We then conducted riding tests to confirm the effects of the improvement measures. We recorded the longitudinal body acceleration data during the riding tests with an accelerometer mounted on the fuel tank, and the effects of improvement were quantitatively confirmed. As a result, by conducting the necessary studies prior to carrying out field tests, we were able to focus on the most promising improvement method, and we were able to provide a far more comfortable riding feeling, thereby receiving a more positive rider's evaluation of longitudinal acceleration.
Keywords: Vehicle Dynamics, Motorcycle, Riding feeling, Simulation