摘要
本論文使用主動式噪音控制(Active noise control, ANC)技術於消音器來抵消汽車引擎噪音。傳統消音器所使用的方法利用消音器中設置不連續管路及擋板孔洞使噪音溢出，透過吸音棉來抵消噪音，但此方法只能抵消高頻噪音且會產生引擎背壓( Back pressure)，導致汽車油耗增加。本論文參考市售消音器外部構造，採用壓克力材料建立大小(296mm(W)*150mm(H)*450mm(L))相同的模型並在消音器內部設置兩個喇叭與直通管，改善傳統消音器無法抵消低頻噪音和背壓的問題。 本論文使用多種演算法在所設置的消音器中來比較系統控制性能。由實驗結果得知，平行窄頻主動噪音控制消噪性能最佳，透過分貝計測量噪音消除能力可達到10dBA。另外本論文在也改善直接/平行窄頻主動噪音控制的噪音分組方式來提升噪音控制性能。本論文也在平行窄頻主動噪音控制的架構下加入回授主動噪音控制形成混合式主動噪音控制(Hybrid ANC)，來增強參考訊號的正確性，改善因引擎轉速改變過快所導致的頻率失真問題。最後本論文使用了主動噪音等化器(Active noise equalizer, ANE)來改變引擎噪音的頻譜，驗證系統功能。
並列摘要
This thesis applies active noise control (ANC) techniques to mufflers to reduce engine noise of vehicles. Conventional mufflers use the passive ways such as sound absorbing materials to block the noise. These methods are effective to reduce high frequency sound; however, the engine noises usually have their main power at low frequencies. Besides, the sound absorbing material in muffler leads to back pressure to the engine, degrading engine power delivery and increasing fuel consumption. An ANC muffler with the sizes 296mm(W)*150mm(H)*450mm(L) was built to verify the performance using the ANC techniques. Two loudspeakers are placed inside the acrylic muffler as the secondary loudspeakers to generate anti-noises to cancel the engine noise. A straight stainless pipe was applied as the exhaust pipe in the muffler without any sound absorbing material. So, the presented work is free from back pressure to the engine. Experimental results compare several ANC algorithms including the direct, the direct/parallel and the parallel structures schemes with simulated 2400 rpm and 3600 rpm engine noises. A modified direct/parallel structure is also proposed to enhance the performance of the noise cancellation. The frequency mismatch problem resulting from acceleration or deceleration of rotating speed of the engine is also investigated. Active noise equalizer (ANE) function is also examined too.
參考文獻
延伸閱讀
- 陳泓宇、白明憲（2018）。基於多通道反濾波原理之主動式管路噪音控制器。應用聲學與振動學刊，10(1&2)，1-7。https://doi.org/10.6282/JASV.201812_10(2).0001
- 廖國鈞（2011）。主動式噪音控制–應用於鼾聲消除〔碩士論文，中原大學〕。華藝線上圖書館。https://doi.org/10.6840/cycu201100541
- 陳光漢、林榮政、王志宏、陳鍊（1997）。主動式噪音控制應用於管線噪音防制。載於中華民國振動與噪音工程學會（主編），中華民國振動與噪音工程學會論文集（頁97-111）。中華民國振動與噪音工程學會。https://doi.org/10.30028/CSSVANNUAL.199705.0097
- 陳冠勳（2018）。主動噪音控制應用於管路型噪音消除〔碩士論文，中原大學〕。華藝線上圖書館。https://doi.org/10.6840/cycu201800008
- 呂昆原、陳坤男、賴文毅、林瑋銘（2015）。Dynamic Characteristics of Automotive Exhaust Systems。載於中華民國振動與噪音工程學會（主編），中華民國振動與噪音工程學會論文集（頁109-114）。中華民國振動與噪音工程學會。https://www.airitilibrary.com/Article/Detail?DocID=a0000192-201506-201509220005-201509220005-109-114