微重力环境中的气体质量流量控制器研究

提出了一种高可靠气体质量流量控制器设计. 介绍了该流量控制器的原理和结构. 通过比较不同的气体流量传感器和阀门, 选择了可满足空间科学实验设备可靠性要求的MEMS传感器和针阀. MEMS质量流量计的输出电压(代表实际气体流量), 经过减法电路放大和A/D采样之后, 与设定电压(代表设定的气流流量)进行比较, 差值信号输入给PID控制器, 由其输出步进电机的控制脉冲数和方向, 步进电机驱动器驱动电机调节流过针阀的气体流量, 使之与设定流量相等. 给出了利用该气体质量流量控制器控制氧气流量的实验结果. 该系统可实现流量的灵活调节, 并具备空间科学实验设备所要求的性能, 为未来在空间利用气体流量连续可调的质量流量控制计进行燃烧科学实验奠定了基础. 

Research of a Mass Flow Controller for Microgravity Environment

A highly reliable method of mass-flow controller design is proposed. The controller is composed of 4 parts, i.e., control circuit, Micro-Electro-Mechanical Systems (MEMS), needle valve and step motor. Different gas flow meters and control valves are compared, and then MEMS and needle valve are selected. The MEMS, as an integrated chip, has better vibration resistance and smaller size, and its working temperature can meet the space experimental requirements. The output voltage from MEMS is amplified by subtraction amplifier circuit, through A/D sampling and software filtering, and an output voltage value is obtained, which denotes the actual gas flow. By comparing the sampling value and the set value of gas mass flow, PID algorithm is used to count step motor control parameters, including the amount of pulse and the direction. Then the needle valve adjusts gas mass flow by step motor to reach the set value of gas mass flow. The experimental results are given by using this gas mass flow controller for oxygen flow control. The whole system can neatly adjust gas flow in demand and reach the experimental requirements for space equipment. It lays the foundation of using mass flow controller in China's future space experiment.