Analysis on Operating Characteristics of Four-position Double-pass Electrothermal Pneumatic Microvalve
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摘要: 本研究提出的四位双通电热气动微阀是在传统气动微阀的基础上,对阀通道结构和控制方法进行创新设计,采用封闭气腔内设置电热片的方式,通过控制电热片的通电与否和电流强度,实现了4个工作位双向导通的控制作用,并根据需要调整压力的阈值; 运用COMSOL软件对电热气动微阀的传热过程、流场特性和阀膜片的受力情况进行数值分析,通过对气腔内部的电流-压力特性、膜片的应力应变特征、流体通道内的速度和压力分布的分析,从而对电热气动微阀的各方面进行分析。研究发现:四位双通电热气动微阀内部膜片的应力主要集中在膜片与气室接触位置和阻流障碍位置;流体通道内的速度和压力变化主要集中在阻流障碍与膜片之间的通道内;当电热器通相应的电流强度时,温度在1 s内可以达到85 ℃左右。Abstract: The four-bit double pass electrothermal pneumatic microvalve is proposed based on the traditional pneumatic microvalve in this research, in which its valve channel structure and control method are innovatively designed: it adopts the way of setting electric heating sheets in the closed air cavity, and controls the electric heating Whether or not and the current intensity, the four-position bidirectional control effect is realized, and the pressure threshold can be adjusted according to needs. The COMSOL software is used to numerically analyze the heat transfer process, flow field characteristics and the force of the valve diaphragm. The current-pressure characteristics inside the air cavity, the stress-strain characteristics of the diaphragm, the velocity in the fluid channel, the pressure distribution, and various aspects of the electrothermal pneumatic microvalve were simulated. The study found that the stress of the diaphragm in the four-bit double pass electrothermal pneumatic microvalve is mainly concentrated in the position where the diaphragm contacts the air chamber and the position of the obstruction obstacle; the speed and pressure changes in the fluid channel are mainly concentrated in the obstruction obstacle and the diaphragm. When the electric heater passes the corresponding current intensity, the temperature can reach about 85 ℃ in 1 s.
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表 1 电热微阀尺寸表
μm h1 h2 h3 h4 h5 d1 d2 d3 d4 1 000 100 500 1 200 300 2 000 2 000 200 300 表 2 四位双通电热微阀功能图
电热片 向右流通 向右不通 向左流通 向左不通 1 - + - + 2 - - + + 注: “+”表示不导电,“-”表示导电。 -
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