基於巢狀式撓性放大機構之壓電噴射閥設計

Abstract

目前主流的壓電噴射閥使用各式壓電放大機構，提供噴射閥撞針擊發膠水所需之運動行程。然而普通的放大機構為獲得足夠的放大倍率，佔據的體積往往較為龐大，造成壓電噴射閥的尺寸無法進一步小型化。為此，本研究提出一款採用改進型巢狀式撓性放大機構的壓電噴射閥。此巢狀式撓性放大機構結合了菱形式、槓桿式及半菱形式三種撓性放大機構設計以提升空間利用率。實際完成之巢狀式撓性放大機構尺寸為33.5 mm × 34.2 mm × 10 mm，透過13.65倍的位移放大率達到207.5 μm之最大行程。壓電致動器之最大推力23.14 N、機構剛性為0.1115 N/μm、共振頻率為1946 Hz，兼顧了結構緊湊性並滿足壓電噴射閥的工作情境。在此放大機構之基礎上，本研究設計一款尺寸為72.7 mm × 69.5 mm × 20 mm之小型壓電噴射閥，並進行對壓電噴射閥實際點膠實驗，以瞭解膠水黏度、擊發間距、開啟時間與壓力等參數對點膠穩定性的影響。量測結果顯示在擊發1000 cP 黏度矽油時，相同擊發參數下之液珠尺寸的一致性相當高，其尺寸數據變異係數皆在1.7 % 以下；且液珠尺寸也隨壓力和撞針開啟時長呈線性的變化。然而在應對較高黏度的矽油時，則遭遇因放大機構出力不足而無法保持穩定擊發的狀況。未來可進一步對壓電噴射閥的輸出力量性能進行改進，以期提升壓電噴射閥的應用範圍。

Piezoelectric jetting dispensing valves commonly adopt various displacement amplification mechanisms to achieve the stroke necessary for precise glue dispensing. However, conventional mechanisms often require bulky volume to realize sufficient amplification ratios, resulting in low spatial utilization and limiting valve miniaturization. To address this, this thesis proposed a compact piezoelectric jetting dispensing valve incorporating an improved nested compliant amplification mechanism. This mechanism integrates three compliant designs—diamond-type, lever-type, and semi-diamond-type—within a compact rectangular space, maximizing spatial efficiency. The developed mechanism measured 33.5 mm × 34.2 mm × 10 mm, achieving a maximum displacement of 207.5 μm and an amplification ratio of 13.65. Its maximum output force, stiffness, and resonant frequency were 23.14 N, 0.1115 N/μm, and 1946 Hz, respectively, demonstrating compactness and jetting suitability. Based on this mechanism, a compact valve was developed. Dispensing experiments investigated the effects of fluid viscosity, firing frequency, opening time, and input pressure on jetting stability. Results showed that with 1000 cP silicone oil, droplet sizes were highly consistent under identical firing conditions and varied linearly with parameter changes. At higher viscosities, limited output force led to unstable jetting. These findings suggest future work should enhance output performance to expand applicability to a broader range of fluids.