Investigation on the Gearbox Radiated Noise Optimization Under Acceleration Conditions of Electric Bus Based on Gear Micro-modification Methods

Abstract

Because of the superior advantages of electric bus on energy saving and emission reduction than the traditional diesel bus, the electric buses are widely used in short-distance travel and urban public transportation. However, during the use of the electric bus, according to the reflection of the passengers and the drivers, the noise was abnormal under the two-gear and the three-gear acceleration conditions. Compared with the traditional diesel bus, the gearbox noise of electric bus is more prominent due to time varying loads effect and the absence of diesel engine masking effect under the acceleration condition, which deteriorates the NVH characteristics of the whole vehicle. Therefore, the gearbox of electric bus is researched as an object in this paper. The test results showed that the radiated noise of the gearbox under the three-gear acceleration condition was significantly higher than the two-gear acceleration condition, and the meshing noise of the shifting gear of the three-gear was found to be the main source of the gearbox radiation noise under the three-gear acceleration condition by order analysis, so the shifting gears of the three-gear were optimized as an object. In this paper, the boundary element radiation noise model has been established in the acoustic radiation software, and the radiated noise model has been verified by the bench test under the three-gear acceleration condition. In order to optimize the gearbox radiated noise under the three-gear acceleration condition, method of gear microscopic modification has been used to optimize the transmission error (TE) and the radiated noise.