Apparatus and method for pressure fluctuation insensitive mass flow control
First Claim
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1. A process control system comprising:
- a process controller including a processor, a sensor interface, and an actuator interface, and configured to generate a control signal as a function of a sensed mass flow and measured fluctuations in pressure of a gas flow controlled by a mass flow controller, wherein the process controller is configured so as to provide a control signal to the mass flow controller that controls the mass flow controller to produce a constant flow of gas at an outlet of the mass flow controller irrespective of fluctuations in pressure of gas at the inlet.
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Abstract
A mass flow controller includes a thermal mass flow sensor in combination with a pressure sensor to provide a mass flow controller that is relatively insensitive to fluctuations in input pressure. The pressure sensor and thermal sensor respectively provide signals to an electronic controller indicating the measured inlet flow rate and the pressure within the dead volume. The electronic controller employs the measured pressure to compensate the measured inlet flow rate and to thereby produce a compensated measure of the outlet flow rate, which may be used to operate a mass flow controller control valve.
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9 Claims
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1. A process control system comprising:
a process controller including a processor, a sensor interface, and an actuator interface, and configured to generate a control signal as a function of a sensed mass flow and measured fluctuations in pressure of a gas flow controlled by a mass flow controller, wherein the process controller is configured so as to provide a control signal to the mass flow controller that controls the mass flow controller to produce a constant flow of gas at an outlet of the mass flow controller irrespective of fluctuations in pressure of gas at the inlet. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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