渦卷壓縮機軸向順從機構設計與應用之研究

Abstract

對於講究節能環保的現代化高效率變頻冷凍空調系統而言，搭載直流無刷變頻馬達之變頻渦卷式壓縮機已成為技術發展之主流。而欲克服渦卷壓縮機因應變頻容量調節伴隨而來的容積壓縮效率變化問題，首要解決之關鍵便是變頻壓縮泵的內部洩漏問題。本研究所探討之渦卷壓縮機軸向順從機構，由作用於固定渦卷背部的背壓機構與提供渦卷間隙控制的懸吊機構所組成。此順從機構可動態調整渦卷間隙使維持於一固定最佳值，以減少當負載變動時因渦卷壓縮腔室間的內部洩漏所造成的容積壓縮效率變化，使渦卷壓縮機得以在負載變動時可持續維持高容積效率。 用於實現高性能變頻低壓外殼型渦卷壓縮機的幾個軸向順從機構的關鍵技術已在本研究中完成開發與調查。首先進行軸向洩漏路徑幾何數學模型建構與數值模擬分析研究，隨後實際開發一軸向順從機構，並裝置於一低壓外殼R22冷媒空調變頻渦卷壓縮機雛型進行性能測試。實驗結果證實，藉由適當的順從機構設計，在各種轉速操作條件，皆可維持雛型壓縮機的高容積效率。而實測結果亦發現，軸向順從機構的作用能擴展空調用渦卷壓縮機可變轉速操作範圍至更高及更低轉速，並提升效率4.7%~13.5%。此外，由實測觀察發現，此軸向順從機構尚可減輕低壓外殻型壓縮機泵體機件運轉碰撞之噪音問題。 最後，為驗證所研究的軸向順從機構設計原理可廣泛適用於不同種冷媒之應用，實際進行了 R410A及R744(CO2)冷媒低壓外殼型渦卷壓縮機雛型開發案例研究，其中導入有限元素法協助進行軸向順從機構設計變更。實驗證實，本研究之軸向順從機構可成功應用於不同種冷媒之壓縮機應用。

A variable-speed scroll-type compressor (STC) with brushless DC convertor motor has become the mainstream of the technological development because of the requirements for energy-saving and environmental protection in modern high-efficiency inverter refrigeration and air conditioning systems. To overcome the problem of the volume compression efficiency change by the inverter capacity adjusting, the primary key to the solution is to solve the internal leakage problem of the variable-speed compression pump. In this study, the axial-compliance mechanism (ACM), which is composed of a backpressure regulating mechanism acting on the fixed scroll back and a suspension mechanism controlling the scroll clearance, was studied. The use of the ACM enables dynamical adjustments, which allow the scroll clearance to be maintained at a fixed optimal value in order to reduce the varying of volume compression efficiency by the internal leakage in the scroll compression chambers and the high volumetric efficiency can thus be maintained while the system load changed. Several critical techniques for accomplishing a high-performance, variable-speed low-pressure-side (LPS) STC with an ACM have been developed and investigated. First, the mathematical model of axial leakage value was constructed, and the advantages of this model were confirmed by numerical simulations and experimental validations with the developed ACM in an R22 LPS STC prototype. The experimental results showed that if the compliance mechanism is designed appropriately, the compressor can achieve a high volumetric efficiency, irrespective of the operating speed conditions. Because of the ACM, the speed range of the variable-speed scroll compressor can be extended and the efficiency can be improved by 4.7–13.5%. In addition, from the experimental observations, a fact was discovered that the ACM can also reduce the noise between the colliding components of the LPS STC. Finally, for the understanding and verification of the proposed ACM design method could be extended its application to different refrigerant STCs. Case studies of a R410A and a R744 (CO2) applications in the LPS STC prototypes was formulated in this study. Furthermore, the application of the finite element method was introduced for the ACM mechanism design changes. From the experiment results, the proposed ACM design methods can successfully applications in these different refrigerant STCs.