Gas mass flow controller and flow calibration method thereof

Abstract

The invention provides a gas mass flow controller and a flow calibration method thereof. The flow calibration device in the gas mass flow controller includes a calibration cavity, a first flow regulating valve and a first state detection unit, an input end and an output of the calibration cavity. The ends are respectively connected with the output end of the first gas pipeline and the input end of the second gas pipeline; the first state detection unit is used to detect the gas state in the calibration cavity; the first flow regulating valve is arranged on the first gas pipeline; The control unit is used for calculating according to the gas state in the calibration chamber and the gas state in the second gas pipeline detected by the flow control device, so as to obtain the flow calibration value and the flow detection value of the flow control device, and based on the flow calibration value and The flow detection value is used for flow calibration. The technical scheme of the present invention can not only perform flow calibration for MFC, but also has simple algorithm, good real-time performance and accuracy, and can also be used as a pressure reducer for MFC.

Description

technical field [0001] The invention relates to the technical field of flow detection, in particular to a gas mass flow controller and a flow calibration method for the gas mass flow controller. Background technique [0002] Gas mass flow controller (Mass Flow Controller, hereinafter referred to as MFC) is used for precise measurement and control of gas mass flow. MFC is mainly composed of shunt, flow detection sensor, flow control device and control device. The flow detection sensor detects the flow in the gas pipeline, and sends out a flow analog signal, which is converted into a digital signal that can be processed by the control device after signal amplification and A / D conversion; the control device is based on the digital signal and user settings. Set the flow value, control the opening of the flow control device, in order to achieve the purpose of precise control of the gas flow. [0003] After the MFC has been working for a period of time, the accuracy will change ...

AI Technical Summary

Problems solved by technology

[0003] After the MFC has been working for a period of time, the accuracy will change due to the influence of the environment, gas or accidental factors. After a period of accumulation, the accuracy of the MFC will exceed the technical indicators of the product. Continued use in this case will affect Product quality is not even usable

In view of this situation, it is necessary to calibrate the MFC. However, at present, the user can only remove the MFC from the equipment and return it to the factory for maintenance, resulting in the shutdown of the equipment. In addition, there will be many uncertain factors in the process of returning to the factory, which will affect economic benefits and waste a lot of money. time

In addition, the existing MFC calibration method is not only complex in calculation, but also poor in real-time and accuracy of calibration

Moreover, the MFC needs to work under stable pressure conditions. Once the pressure exceeds the pressure working range of the MFC or the pressure fluctuation is too large, the MFC cannot work reliably. Therefore, the gas circuit needs to be equipped with a pressure reducer separately, but this not only increases the cost , and it will take up space resources, especially for semiconductor devices where space is very precious

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