[[alternative]]Design and Modal Analysis for Dynamic Balance Mass of the Reciprocating Air Compressor Crankshaft

碩士機電工程學系[[abstract]]本研究旨在改善往復式空壓機運轉時的振動問題，尋求曲軸最佳配重。在研究中，主要目的為設計適當的曲軸配重，將可有效的縮減往復式空壓機的振動程度，且可縮小曲柄連桿機構的運動軌跡。而縮小此運動軌跡相當於減少因不平衡所引起之振動量。 研究中吾人先以解析解方式建立一個數學模式，根據空壓機尺寸與驅動規格，設計出一個符合空壓機振動與噪音要求的曲軸設計；使用有限元素軟體模擬曲軸在不同的配重下，曲軸的模態與變形情況，並利用頻譜分析儀搭配擊鎚與加速規進行模態測試用以驗證比較，建立一套完整曲軸配重設計與分析的流程。在曲軸實體加工且安裝後，吾人利用振動噪音計於往復式空壓機運轉時進行振動與噪音量測，得知本研究所設計之曲軸可降低空壓機振動量達50.62%，並驗證曲軸配重設計的可行性。[[abstract]]Improving the vibration problem is the main goal of this study for finding the optimal crankshaft counterweight of the reciprocating compressor. Therefore this research mainly aims for designing the appropriate crankshaft counterweight with effective way to reduce the vibration for a commercial reciprocating compressor. As the counterweight reduces the kinetic orbit of crankshaft connecting rod, the decreasing unbalanced orbit corresponds to less vibration. First, we will establish an analytical model for computing the counterweight of the crank based on the dimension of air compressor and drive specifications. Design issue is created for a new crankshaft that fit the air compressor with vibration and noise requirements. Finite element software is used to simulate the modal and deformed situation under variant weight of the crank. Besides, spectrum analyzer for modal testing is introduced for analyzing signals from impulse hammer and accelerometer. Through analytical, simulation and experimentation, this research develops a complete process for crankshaft counterweight design. The designed crankshaft counterweight is implemented and verified through vibration reduction of 50.62%. Experimental result validates this research output