- 會議論文
直流馬達與齒輪箱之噪音分析與改善
Noise Analysis and Improvement on Motors and Gearbox
摘要
本研究主要探討直流有刷馬達之噪音，經由量測分析得知其振動來源（齒輪及電刷）及最終噪音發聲體（馬達或減速機外殼），發展出一個降低旋轉機械類產品噪音之分析流程。流程中除了對馬達在特定的轉速進行振動與噪音測試外，另外在馬達之運轉範圍內進行升速的測試，以便使用階次追蹤分析法來釐清振動與噪音之信號與旋轉元件之間的關係。此外，若馬達之激振頻率（基本轉速頻率或其倍頻）有引發結構共振之虞，則應進行模態測試，以釐清共振所造成的影響，並將馬達之噪音值與振動量做比較，以確認問題噪音之頻率係由振動所產生，進而尋求適當的解決方案來改善（降低）馬達的噪音。在本研究之案例一中，發現馬達之高頻異音係因電刷激振頻率之諧頻引發馬達共振，在振動之傳遞途徑上施以阻絕並提高整流片之精度後，即可將馬達之總噪音量降低6.6dB（A）；在案例二中，馬達特定頻率之噪音係因齒輪箱與馬達之接合平面垂直度不佳所致，經改善後齒輪之嚙合單頻噪音1350Hz即可大幅降低11.5dB（A）。在案例三中，馬達特定頻率之問題噪音係因嚙合之齒輪對精度不足所引起，提高其加工精度後，該嚙合單頻噪音435Hz可降低21.4dB（A）。
並列摘要
This paper investigated the techniques of reducing noise generated from DC motors and their gearbox assemblies. An analysis flow chart was developed to reduce the noise from either the sources (gears and armature) or the final sound radiators such as the housings of the motors and gearboxes. Noise and vibration spectra of the motor-gearbox assemblies were first measured to assure the noise problems are caused by vibration. Running up the motors' speeds in their operating range is necessary in order to use the ”order tracking analysis” to clarify the relationship between signals and the corresponding rotating parts. Further down the stream, if resonance is speculated to be caused by excitation frequencies from fundamental frequency or its harmonics, ”modal testing” must be performed to evaluate the influence of the resonance. After that, appropriate means are then proposed to reduce the noise of machines. In this study, real cases from industry verified the practicality of the developed flow chart. In the first case, the high pitch noise was caused by resonance of the motor housing which was induced by the harmonics of the brush frequency. After isolating the transmission path of vibration and improving the precision of commutators, the total noise was reduced by 6.6 dB(A). In case II, the noise at specific frequencies was caused by insufficient verticality at the jointing planes between the motor and the gearbox. After correction, the misaligned meshing gear noise at 1350Hz was reduced by 11.5 dB(A). In the last case, the noise was produced from the meshing gears. After improving the precision of meshing gears, the meshing gear noise at 435 Hz was reduced by 21.4 dB(A).