US 12,259,739 B2
Advanced pressure based mass flow controllers and diagnostics
Arun Nagarajan, Freemont, CA (US); Daniel Mudd, Freemont, CA (US); and Mohamed Saleem, Freemont, CA (US)
Assigned to Illinois Tool Works Inc., Glenview, IL (US)
Filed by Illinois Tool Works Inc., Glenview, IL (US)
Filed on Nov. 19, 2019, as Appl. No. 16/688,950.
Claims priority of provisional application 62/841,110, filed on Apr. 30, 2019.
Prior Publication US 2020/0348702 A1, Nov. 5, 2020
Int. Cl. G05D 7/06 (2006.01); G01F 1/00 (2022.01); G01L 9/00 (2006.01)
CPC G05D 7/0623 (2013.01) [G01F 1/00 (2013.01); G01L 9/0098 (2013.01); G05D 7/0617 (2013.01); G05D 7/0647 (2013.01); G05D 7/0635 (2013.01)] 18 Claims
OG exemplary drawing
 
1. A mass flow controller for controlling fluid flow rate, the mass flow controller comprising:
a valve assembly comprising at least one valve and being in fluid communication with at least one upstream location and at least one downstream location in a same flow path as the upstream location, wherein the at least one valve has a valve stem and a valve seat;
at least one semiconductor based pressure sensor in fluid communication with the at least one upstream location and the at least one downstream location;
a position sensor communicably coupled with the at least one valve; and
a controller communicably coupled with the valve assembly and the at least one pressure sensor, wherein the controller is configured to:
determine pressures for the upstream location and the downstream location; and
control the valve assembly to adjust a valve stroke of the at least one valve in fluid communication with the upstream and downstream locations based on an actual fluid flow rate and a desired positive fluid flow rate;
receive a value indicative of a measurement of an actual position of the valve stem from the position sensor as the valve stem moves from the valve seat following the adjustment; and
perform diagnostics on the mass flow controller by comparing the actual position of the valve stem relative to a predetermined position of the valve stem, the predetermined position of the valve stem determined in response to the desired positive fluid flow rate, the predetermined position determined from a predetermined relationship between the pressures for the upstream location and the downstream location and the position of the valve stem, and determined from a predetermined relationship between the desired positive fluid flow rate and the valve stroke.