Method and system for a mass flow controller with reduced pressure sensitivity
DCFirst Claim
1. A flow controller with reduced sensitivity to pressure, comprising:
- an inlet;
an outlet;
a flow path coupled to the inlet and the outlet;
a flow sensor coupled to the flow path;
a control valve downstream of the flow sensor and upstream of the outlet; and
a control system operable to;
generate a first signal corresponding to a time rate of change of pressure sensed by a pressure sensor coupled to the flow path;
receive a second signal corresponding to a setpoint for the flow controller;
receive a third signal corresponding to a measured flow determined by the flow sensor;
generate an error term by combining each of the first signal, the second signal and the third signal; and
adjust the flow controller based on the error term,wherein a volume of the flow path downstream of the flow sensor and upstream of the control valve is optimized.
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Abstract
Systems and methods for mass flow controllers which minimize false flow conditions and display a reduced sensitivity to pressure transients are disclosed. Pressure gradients that exist within the volume of a mass flow controller fluid path are minimized in order to limit the potential energy contained in compressed or pressurized process gas. Additionally, process gas pressure may be monitored using a pressure sensor. This pressure signal is utilized in conjunction with a control algorithm to cancel the detrimental effect of certain flow components. These mass flow controllers may be used as drop in replacements for legacy mass flow controllers and reduce the cost of gas sticks due to elimination of discrete components such as pressure regulators, gas filters, pressure transducers, local pressure displays, isolation valves, seals, etc.
134 Citations
44 Claims
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1. A flow controller with reduced sensitivity to pressure, comprising:
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an inlet; an outlet; a flow path coupled to the inlet and the outlet; a flow sensor coupled to the flow path; a control valve downstream of the flow sensor and upstream of the outlet; and a control system operable to; generate a first signal corresponding to a time rate of change of pressure sensed by a pressure sensor coupled to the flow path; receive a second signal corresponding to a setpoint for the flow controller; receive a third signal corresponding to a measured flow determined by the flow sensor; generate an error term by combining each of the first signal, the second signal and the third signal; and adjust the flow controller based on the error term, wherein a volume of the flow path downstream of the flow sensor and upstream of the control valve is optimized. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A system for reducing the sensitivity of a flow controller to pressure, comprising:
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a pressure sensor; a flow controller, including; an inlet; an outlet; a flow path coupled to the inlet and the outlet; a flow sensor coupled to the flow path; and a control valve downstream of the flow sensor and upstream of the outlet; and a control system operable to; generate a first signal corresponding to a time rate of change of pressure sensed by the pressure sensor; receive a second signal corresponding to a setpoint for the flow controller; receive a third signal corresponding to a measured flow determined by the flow sensor; generate an error term by combining each of the first signal, the second signal and the third signal; and adjust the flow controller based on the error term. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. A gas stick with reduced sensitivity to pressure disturbances, comprising:
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a pressure sensor coupled to the gas stick; a flow controller coupled to the gas stick, including; an inlet coupled to the gas stick; an outlet coupled to the gas stick; a flow path coupled to the inlet and the outlet; a flow sensor coupled to the flow path; and a control valve downstream of the flow sensor and upstream of the outlet; and a control system coupled to the flow controller, the control system operable to; generate a first signal corresponding to a time rate of change of pressure sensed by the pressure sensor; receive a second signal corresponding to a setpoint for the flow controller; receive a third signal corresponding to a measured flow determined by the flow sensor; generate an error term by combining each of the first signal, the second signal and the third signal; and adjust the flow controller based on the error term. - View Dependent Claims (32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44)
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Specification