Flow rate control using mass flow rate control device

摘要

A process and device enabling accurate mass flow control is described. A mass flow controller can be re-specified corresponding to multiple types of actual process gases and multiple flow rate ranges, even after the mass flow controller has been shipped. Calibration gas data is derived using actual flow rate versus a flow rate setting signal to generate calibration gas data. Actual gas data is derived by measuring actual flow rate versus a flow rate setting signal for each actual gas and saving. Subsequently, prior to operating the mass flow rate control device, the characteristic data for an actual and the calibration gas characteristic data is recalled. The calibration gas characteristic data is then converted to controlled flow rate correction data based on the actual gas characteristic data that is saved to the control unit and the actual gas flow rate is corrected based on this controlled flow rate correction data.

主权项

1. A method for controlling flow rate of a gas flowing on a flow path, comprising the steps of:
(a) providing a flow rate control device configured to perform feedback control of a flow rate of a gas flowing on a flow path based on a target flow rate and a sensed flow rate, wherein the target flow rate is a target value for an intended mass flow rate of the gas flowing on the flow path, and wherein the sensed flow rate is a sensed mass flow rate of the gas flowing on the flow path; (b) providing control data that includes a plurality of control parameters respectively associated with mutually different mass flow rates wherein the control data is associated with a type of the gas flowing on the flow path, and wherein said providing of the control data comprising the steps of:
(b1) providing first characteristic data that includes a plurality of first characteristic parameters respectively associated with flow characteristics of a standard gas through the provided flow rate control device, wherein the first characteristic parameters are associated with mutually different mass flow rates for the standard gas through the provided flow rate control device, and wherein the first characteristic data is stored in semiconductor memory of a storage unit of the flow rate control device;(b2) providing second characteristic data that includes a plurality of second characteristic parameters respectively associated with mutually different mass flow rates of at least one working gas that is different than the standard gas, wherein the second characteristic parameters reflect standardized characteristics of the flow of the working gas in a class of flow rate control devices that includes the control rate flow device relative to the flow of the standard gas through the class of flow rate control devices, and wherein the second characteristic parameters are saved to a swappable computer readable medium, the swappable computer readable medium itself capable of being swapped out more easily than the storage unit of the flow rate device and wherein the swappable computer readable medium is not semiconductor memory; and(b3) reading the first characteristic data from the storage unit, reading the second characteristic data from the swappable computer readable medium, and generating the plurality of control parameters based on the first and second characteristic parameters thereby generating the control data, (c) generating a corrected sensed flow rate based on the sensed flow rate and a selected one of the plurality of control parameters, wherein the selected control parameter is determined based on at least one of the sensed flow rate and the target flow rate; and (d) controlling the flow rate of the gas flowing on the flow path by using feedback control using the flow rate control device and referring to the control data, based on at least one of the target flow rate, the corrected sensed flow rate, and a control parameter that is determined based on at least one of the target flow rate and the sensed flow rate from among the plurality of control parameters.