車輛之振動噪音是影響舒適性的重要指標,電動車除去了引擎點火燃燒之激振源;相形之下,在一般道路駕駛時,變速箱換檔所引起的瞬間不平滑振動就變得更顯著。因此本論文主要針對電動中型巴士在平滑路面行駛時,探討變速箱換檔時的振動噪音現象。 研究中,應用電腦輔助工程設計軟體SolidWorks來建立電動中型巴士三維設計圖,分析模型是使用前處理器HyperMesh建置有限元素模型。所建置的分析模型與實車量測所得之頻率響應結果相比,以驗證模型之正確性。對全車之振動分析是使用LS-Dyna套裝軟體內的穩態動力響應(Steady State Dynamics Response, SSD),噪音分析則是應用邊界元素法(Boundary Element Method, BEM)。依分析所得之振動噪音路徑,改善車艙內噪音以及駕駛和乘客乘坐之舒適性。 研究結果顯示,改變馬達腳橡膠形狀以及車體結構的厚度對振動噪音改善有很大的影響,改善後,駕駛座以及乘客座振動噪音最大可有效減少68%。
Vehicle noise and vibration is one of key indicator for riding comfort. Electric vehicles do not have the vibration excitation triggered by engine firing; therefore, the smoothness of gear shifting seems relatively important for regular street drive. This thesis focuses on the effect of gear shifting to the noise and vibration of a midsize electric bus. In the study, the computer aided design tool, SolidWorks, is used to create the three-dimensional structure of the bus; and a pre-processor, HyperMesh, is used to establish the analysis model. The analysis model is validated with hardware testing. The full vehicle vibration analysis is performed using Steady State Dynamics Response of LS-Dyna software, and interior sound pressure is carried out using Boundary Element Method. Based on the noise path analysis, improvement is proposed. The results show that the motor mounts and the structures have significant impact to the noise and vibration of the vehicle. Through the optimization, 68% improvement is reached.