壓縮機為冷凍空調系統中重要的噪音源之一，由噪音傳遞的原理與途徑可以分成結構傳遞音與流場傳遞音兩大類型，消音罩及儲液器為壓縮機中重要的消聲器組件，本研究中特別討論此二部分的聲場特性。迴轉式壓縮機屬容積式壓縮機，因其週期性間歇式進排氣行為，產生強烈的進排氣壓力脈衝，導致氣流脈衝的壓力擾動行為顯著，其次變頻壓縮機其轉速頻率也會影響壓縮機內聲場特徵。本研究從2100 RPM至4800 RPM的轉速進行殼內聲壓泵浦段與吐出口段的量測，結果清楚地呈現除了有隨著壓縮機轉速倍頻變化的特徵頻率以外，聲場特徵並不會因為壓縮機運轉速度的不同而有很大差異。本論文中亦有進行殼外聲場量測，因壓縮機殼外噪音受到機殼強度與結構模態的影響，結果亦顯示殼內、外聲場特性相近，聲場特徵不會因為壓縮機運轉速度的不同而有很大差異。 為研究壓縮機消音器的減噪特性，本研究亦進行消音罩吐出口直徑大小(3mm、4mm及7mm)參數修改的比較，結果中呈現吐出口直徑大小3mm、4mm之組合其消音特性，殼內與殼外各轉速聲場特性趨勢相同，在低頻段(0 Hz~1600 Hz)效益非常大，尤其於300 Hz~900 Hz與1100Hz~1200Hz的頻帶之間有著明顯的抑制效果。 除此之外，還經由模擬分析結構特性與實驗量測比對，探討儲液器結構對振動噪音的影響性。經模擬結果發現儲液器為無隔板形式時，其模態振型主要來自內管擺動及外壁的變形。而實驗結果可以看出有裝設隔板設計對於儲液器聲場的影響。儲液器實驗與模擬結果比對具有相同的特性結果。 ;Compressor contributes significant noise in an air-conditioning system. The rotary compressor considered here is a positive displacement compressor because of its periodic intermittent intake and exhaust. The strong intake and exhaust pressure pulses can affect the fundamental frequency of the sound in the compressor. On the other hand, different operating speeds of the motor give similar envelope of frequency domain sound. This can be proved from the internal sound measurements in the pump section and in the discharge section for rotation speed 2100 RPM to 4800 RPM. In this research, the sound field outside the casing was also measured and discussed. The muffler and the accumulator in the compressor are the most important components designed to reduce the noise. The sound field characteristics of these two parts were discussed. This research studied the measured sound from two different mufflers; and the one with two spouts (diameters 3mm and 4mm) preforms better than the one with one larger spout (diameter 7mm). In addition, the vibration char-acteristics of the accumulator structure were numerically and experimentally inves-tigated. The simulated natural frequencies of the structure are close to the experiment result. The frequency domain of measured sound also show peaks at frequencies near the simulated natural frequencies. Then, the effect of adding inner plate in the ac-cumulator was analyzed by studying the measured sound pressure.
