Apparatus and method for self-calibration of mass flow controller
First Claim
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1. A self-calibrating mass flow controller, comprising:
- a mass flow sensor configured to produce an electronic signal representative of mass flow in the mass flow controller as a function of the flow sensed by the sensor;
a mass flow calibrator operative to produce an independent electronic signal representative of mass flow in the mass flow controller as a function of the flow sensed by the calibrator, the mass flow calibrator includes a pressure sensor operative to measure pressure of gases within a receptacle of predetermined volume between a bypass included in the mass flow sensor and an outlet control valve; and
an electronic controller configured to correlate the mass flow signal from the mass flow sensor to the rate of flow indicated by the independent electronic signal from the mass flow calibrator.
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Abstract
A mass flow controller includes a mass flow sensor and a calibrator configured to perform a self-calibration on the mass flow controller. The calibrator generates flow measurements that are used as “standards” and flow measurements from the mass flow sensor are correlated to flow measurements from the calibrator.
80 Citations
54 Claims
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1. A self-calibrating mass flow controller, comprising:
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a mass flow sensor configured to produce an electronic signal representative of mass flow in the mass flow controller as a function of the flow sensed by the sensor;
a mass flow calibrator operative to produce an independent electronic signal representative of mass flow in the mass flow controller as a function of the flow sensed by the calibrator, the mass flow calibrator includes a pressure sensor operative to measure pressure of gases within a receptacle of predetermined volume between a bypass included in the mass flow sensor and an outlet control valve; and
an electronic controller configured to correlate the mass flow signal from the mass flow sensor to the rate of flow indicated by the independent electronic signal from the mass flow calibrator. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A self-calibrating mass flow controller comprising:
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a thermal mass flow sensor configured to sense the flow of gas in the mass flow controller and to produce an electronic signal representative of the sensed flow;
an electronic controller;
an outlet control valve operated by the controller to allow a predetermined flow of gas through the mass flow controller; and
a pressure sensor operative to measure the pressure of gas within the receptacle formed between the thermal mass flow sensor'"'"'s bypass and the outlet control valve, the receptacle thus-formed being of predetermined volume, the electronic controller configured to operate the outlet valve to vary the flow through the mass flow controller, to take the time derivative of the pressure signal, to normalize the time derivative signal, and to correlate the signal from the thermal mass flow sensor to the normalized time derivative signal. - View Dependent Claims (21, 22, 23, 24, 25)
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26. A method of self-calibrating a mass flow controller that includes a mass flow sensor, an electronic controller, and a mass flow calibrator, comprising the steps of:
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a mass flow controller'"'"'s mass flow sensor producing an electronic signal representative of mass flow in the mass flow controller as a function of the flow sensed by the sensor;
the mass flow controller'"'"'s mass flow calibrator producing an independent electronic signal representative of mass flow in the mass flow controller as a function of the flow sensed by the calibrator, the mass flow calibrator includes a pressure sensor operative to measure pressure of gases within a receptacle of predetermined volume between a bypass of the mass flow sensor and an outlet control valve; and
the mass flow controller'"'"'s electronic controller correlating the mass flow signal produced by the mass flow sensor in response to its sensed flow within the mass flow controller to the flow indicated by the independent electronic signal produced by the mass flow calibrator in its sensing of flow in the mass flow controller. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46)
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47. A method of calibrating a self-calibrating mass flow controller comprising the steps of:
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a thermal mass flow sensor sensing the flow of gas in the mass flow controller and producing an electronic signal representative of the sensed flow;
an electronic controller operating an outlet control valve to allow a varied flow of gas through the mass flow controller; and
a pressure sensor measuring the pressure of gas within the receptacle formed between the thermal mass flow sensor'"'"'s bypass and the outlet control valve, the receptacle thus-formed being of predetermined volume;
the electronic controller taking the time derivative of the pressure signal, normalizing the time derivative signal, and correlating the signal from the thermal mass flow sensor to the normalized time derivative signal. - View Dependent Claims (48, 49, 50, 51, 52, 53, 54)
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Specification