Development of Rumble Noise Analysis Method for Electric Powertrain

<div class="section abstract"><div class="htmlview paragraph">In electric-powertrains, noise and vibration can be generated by components such as gears and motors. Often a noise phenomenon known as rumble or droning noise can occur due to low shaft order excitation at the spline. In this study, we identified the excitation source for spline induced rumble noise and developed a novel analysis method. First, a detailed spline model, believed to be the key factor for rumble noise, has been developed and verified by comparison with Finite Element Method(FEM) analysis. In order to identify an excitation source, a typical electric-powertrain assembly model including the developed spline model was constructed and simulated. Results according to changes of key factors including spline pitch errors and shaft alignment errors were analyzed. Spline radial force has been identified as an excitation source of spline induced rumble noise. This was verified through comparison with the forced vibration analysis result and time domain analysis result. This paper presents two methods for simulating spline rumble, including the key contributing factors of spline pitch errors, shaft alignment errors and unbalanced mass. Time domain method is accurate but slow. So, a faster, lower fidelity quasi-static approach has been developed and verified using time domain analysis results. Finally, an analysis process for each development stage has been established utilizing the two simulation methods. In concept design stage, quasi-static analysis is appropriate to identify robust structure for rumble noise. In detailed design stage, manufacturing tolerances could be adjusted by reviewing various conditions for rumble noise through quasi-static analysis, and a direct response review through time domain analysis is also useful to check for problems.</div></div>