迴轉式壓縮機零組件之結構聲場耦合分析

變頻冷氣機中的迴轉式壓縮機，經常有振動與噪音的問題，因壓縮機運轉時會有轉速變化，對內部工況產生轉速與溫度的變化，影響冷媒的溫度與壓力，常有流動的噪音產生。本文特別針對冷媒流動的組件如過濾瓶及缸體內部泵組合件之消音罩，探討結構與冷媒相互影響所產生的振動與噪音。首先由模型驗證(model verification, MV)，確認過濾瓶與消音罩組件的分析模型，主要有兩項工作，實驗模態分析(experimental modal analysis, EMA)與有限元素分析(finite element analysis, FEA)，FEA包含了模態分析和簡諧響應分析。進行過濾瓶FEA時，由於有限元素模型是影響分析結果的關鍵之一，為了取得過濾瓶的有限元素模型，因此需進行過濾瓶的模型更新，再比對EMA之模態參數。接著透過FEA取得的等效過濾瓶的分析模型，建立純空腔聲場分析模型及結構振動與聲場耦合分析模型。探討過濾瓶不同系統模型的差異，比較結構的振動、結構內部及外部的聲音壓力特性，並且也建立了聲場分析概念的基礎。本文除了針對過濾瓶結構，也對消音罩進行模型驗證與聲場分析，探討結構的振動與聲場特性。為了探討壓縮機缸體內部的消音罩聲場特性，分別進行了聲場模態分析和聲場簡諧響應分析，也分別取得消音罩內部的純空腔聲場系統，以及結構振動與聲場耦合系統的傳遞損失(transmission loss, TL)，並且比較兩種系統模型的TL差異。結果顯示，在TL的截斷頻率，其對降低聲音幾乎沒有影響，會對應於消音罩的腔體聲場模態，此特性有助於消音罩之設計分析。此外，進行了壓縮機運轉時有無消音罩之實驗量測，並比較其聲音壓力頻譜差異，確實和消音罩TL有相當程度的關聯性。本文針對過濾瓶與消音罩建立了結構聲振耦合分析技術，可供未來研究整機壓縮機系統的聲場分析，輔助壓縮機零組件的開發設計以降低振動與噪音。

關鍵字

過濾瓶；純空腔聲場分析；消音罩；結構聲振耦合分析；模型驗證；傳遞損失

並列摘要

When the rotary compressor is running in the inverter air conditioner, there are often noise and vibration problems. When the rotation speed changes in operation, the rotation speed and temperature change due to the internal working conditions, which affect the temperature and pressure of the refrigerant, and there induce flow fluctuation noise. This work aims to discuss the interaction between the structure and the refrigerant, resulting in noise and vibration, for those components such as the accumulator and the muffler cover of the pump assembly inside the cylinder. This work conducts model verification (MV) to verify the numerical model of the accumulator and the muffler cover. MV is divided into two main tasks, i.e. experimental modal analysis (EMA) and finite element analysis (FEA). FEA includes modal analysis and harmonic response analysis. In performing the FEA of the accumulator, the finite element model is one of the keys that affect the analysis results. To obtain the finite element model of the accumulator, it is necessary to update the model and then compare the modal parameters from the EMA. Based on the obtained equivalent model of the accumulator, the pure cavity acoustic analysis model and the structure vibroacoustic coupling analysis model can then be established and analyzed. This study shows the differences between different system models of the accumulator, compares the vibration of the structure, and the sound pressure characteristics inside and outside the structure, and also establishes the basis for structural vibroacoustic analysis. In addition to the accumulator structure, the model verification and structural vibroacoustic analysis of the muffler cover are also carried out to discuss the vibration and acoustic characteristics of the structure. To study the sound transmission characteristics of the muffler cover inside the compressor cylinder, both the acoustic modal analysis and the acoustic harmonic response analysis are performed to examine the Transmission Loss (TL) for the pure cavity acoustic system inside the muffler cover as well as for the structure vibroacoustic system. This study compares the TLs between the structure vibroacoustic coupling analysis and the pure cavity acoustic analysis for the muffler cover. Results show the cutoff frequencies of TL, which with little effect on reducing sound, correspond to the cavity acoustic modes. This provides a clue for the muffler design. The sound pressure spectra of the compressor measured experimentally with and without the muffler cover are compared and correlated to TL having a considerable agreement. This work establishes the structure vibroacoustic analysis techniques for the accumulator and the muffler cover that can be extended to other components or even the compressor system. This will lead to assist development and design of compressors in reducing noise and vibration.

並列關鍵字

Accumulator ； Pure Cavity Acoustic Analysis ； Muffler Cover ； Structure Vibroacoustic Coupling Analysis ； Model Verification (MV) ； Transmission Loss

參考文獻

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