可變負重之二連桿與平行四連桿機構的設計

Abstract

本文提出一個可變負重的二連桿與平行四連桿機構的設計。一個可承載負重，且在任何位置都能完全抵消重力影響的機構稱為重力平衡機構。重力平衡機構可不費力的在與重力方向平行的方向上移動，且在任何位置都能達到靜平衡。本研究以二連桿與平行四連桿機構為基礎，可平衡不同負重的重力平衡機構。 藉由分析二連桿中重力位能在二連桿上的負重與桿件間夾角改變時的變化情形，並利用達到平衡時總能量恆為定值的原理，可以得到相對應的彈力位能形式。藉由求出的彈力位能方程式可得出平衡負重可變的二連桿機構的彈簧安裝方式。 由於平行四連桿機構與二連桿機構具有相似運動特性，重力位能在負重與桿件間夾角改變時的變化情形也與二連桿機構相似，所以可將在二連桿得出的彈簧安裝方式應用在平行四連桿機構上，得出一個可變負重的平行四連桿機構設計。

ABSTRACT The design of 2-bar and 4-bar parallelogram mechanism with load adjusting ability is presented. A mechanism which sustains the load, and compensates the effect of gravity is called “Gravity Equilibrator”. A gravity equilibrator can be moved in corresponding to the direction of gravity effortlessly and achieve static balance in any position at the same time. The design in this paper is therefore based on the 2-bar and 4-bar parallelogram mechanisms which compensate variable load of the mechanism. Through employing the methodology of conservation of potential energy, and by analyzing the variation of potential energy of 2-bar mechanism while the load and the angle between bars are varied, the spring potential energy can thus be obtained. The installation of springs on 2-bar mechanism can thus be gained by the spring potential energy. Since the 4-bar parallelogram mechanism is similar to the 2-bar mechanism, the spring installation on the 2-bar can then also be applied to the 4-bar parallelogram mechanism.