微型氣壓振動器之設計開發與性能研究

Abstract

傳統高頻振動器多使用壓電效應或磁變形效應的原理。電氣式振動器的熱效應一直是為人詬病的特性。本論文利用氣體自我降溫的特點，以氣體軸承氣壓致振的原理，開發設計小型、高功率輸出、高效率的高頻振動器。設計上使用兩個對向配置的軸向氣體軸承，將其間的致動件來回推擠，利用微小氣膜間隙下氣體可壓縮性所產生的不穩定現象，使致動件產生振動的效果。性能分析透過理論計算與有限元素模擬，對承載力、剛性與激振頻率作出預測；實驗則包含無負載、負載特性的量測，最後透過振動影響參數質量和彈簧負載的調整，提出具體設計改良。實驗成果驗證了氣鎚現象作為氣壓式振動器原理的可行性，系統為一直徑30mm、高31mm 之圓柱體結構，測試頻率最高為5.4kHz，供氣壓力4bar 時質量負載可達1kg，最高有65%的能量轉換效率和66W 的功率輸出，經由設計改良，振動器的性能可獲得進一步的提升。

Most conventional high-frequency vibrators generate the working power based on the piezoelectric and magnetostrictive effects. After entering the transducing system, the input time-varying electric energy will then be transferred into solid-body vibration; however, the heat dissipated has always been a critical issue of such vibrators. Therefore, the objective of this research was to develop a miniature high-frequency vibrator with high power output and high energy efficiency, which took advantage of the self-cooling property of gas and the pneumatic instability to trigger the vibration motion. Two aerostatic bearings were placed in the opposite configuration with the driven part oscillating back and forth due to the pneumatic hammer phenomenon. Full analysis was done by both theoretical calculation and finite element method. Predictions of load capacity, equivalent stiffness, and excited vibrating frequency were all proved possible and applicable while measurements of the unloading and loading characteristics of the vibrator were carried out by experiments. Besides, parameters including driven mass and spring loading effect were examined to a thorough understanding. In the end, modifications for the designed vibrator were proposed to acquire better system performance.