引擎振動系統的減振研究

Abstract

引擎振動系統的減振研究 研究生：陳俊行 指導教授：金大仁 博士 國立交通大學機械工程研究所 中文摘要 本文的研究方向在建立一個引擎系統減振分析的套裝軟體來模擬評估多自由度引擎系統振動的情況，設計方法是模擬引擎系統為一個立體方塊模組，引擎模組表面任意三點有彈簧墊片支撐，受引擎運轉時的週期性作用力影響產生振動。在此正常條件下，探討如何重新設計引擎懸吊系統的支撐方法，來達成降低引擎正常運轉時的振動量。避免正常行駛時產生的衝擊震盪傳至車內其他的零件上造成損傷，藉此提高引擎振動系統整體的可靠度。 在理論方面，根據振動學中模態分析的觀念，來推導立體六自由度系統運動的可能情形。經由已知振動系統的剛性、質量、支撐彈簧墊片放置位置與阻尼係數、引擎在三十筆轉速下共三百筆作用力頻率與任意轉速下任意頻率時量測引擎上三點的主軸方向加速度絕對值和相對應的相位角，來計算出此時引擎系統內部藉由汽缸與變速箱運轉時產生的激振。並以此時的簡諧激振力，來設計變更振動系統的剛性、支撐彈簧墊片放置位置與阻尼係數，來避開引擎系統產生不穩的共振問題，並提供適合支撐引擎的懸吊系統，使引擎內產生的振動傳至車身其他系統時，達成穩定而明顯的減振效果。 在使用介面方面，使用AutoCAD繪圖軟體中AutoLISP的執行動作功能支援下，直接由Fortran主程式連結至AutoCAD來做一個系統參數輸入與相對應3D瀑布狀頻譜圖輸出的表示。並在執行AutoLISP程式的同時，利用AutoCAD繪圖軟體中DCL ( Dialogue Control Language )的AutoCAD程式表像化功能，建立自己所需特殊的交談框，在多樣化的介面與提供AutoLISP程式執行時所需的資料或選項於一身下，使程式使用介面更人性化且容易執行，未來更可經由實際實驗對照，發展成為最佳化設計引擎系統減振目的之套裝軟體，進而大幅改善工程師操作使用上的工作效益。

A Study of Vibration Suppression of Engine Systems Student : Jyun-Sing Chen Advisor : Dr. Tai-Yan Kam Institute of Mechanical Engineering National Chiao Tung University Abstract The purpose of this paper is to construct a software for an analysis of vibration suppression of an engine system, which is simulated as a six-degrees of freedom system. In the vibration analysis, the engine system is treated as a solid block supporting by a number of springs, which is excited by internally generated forces. Here we establish a method to redesign suspension system to support the engine and achieve an objective of decreasing vibration when the engine works normally so that the effects of engine vibration transmitting to other components can be reduced and the reliability of the whole engine oscillation system can be improved. In the theoretical aspect, the concept of modal analysis is used in the vibration analysis and design of the engine system. The internal forces of the engine system at any rotational speed are first identified for given stiffness, mass, and damping matrices using measured accelerations at some specific point on the engine system. We then use the periodic internal forces to redesign stiffnesses and positions of the supporting springs and damping coefficient of the system to reduce its vibration responses. To facilitate the analysis and redesign processes, we make a connection between Fortran main program and AutoCAD interface to input parameters and output a three-dimentional waterfall shape frequency spectrum which is accomplished by writing the AutoLISP program in AutoCAD interface ( Computer Aided Drafting software ). Furthermore, we take advantage of the program's presentment function and use the DCL program ( Dialogue Control Language ) to devise our own special dialog boxes ( Program Dialog Boxes ) which are full of varieties and make user interfaces smarter and easier to execute. In the future, the program can be expanded to include more functions, and become more powerful by using optimization theory in the design of the engine system.