The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 18, 2016
Filed:
Feb. 13, 2014
Junhua Ding, Boxborough, MA (US);
Michael L'bassi, Sterling, MA (US);
Junhua Ding, Boxborough, MA (US);
Michael L'Bassi, Sterling, MA (US);
MKS Instruments, Inc., Andover, MA (US);
Abstract
A mass flow controller comprises: a pressure-based flow meter, a thermal-based flow meter, a control valve, and a system controller. The pressure-based flow meter and thermal-based flow meter each measure flow rate of mass through the mass flow controller. The control valve controls the flow rate in response to a control signal generated as a function of the flow rate as measured by thermal-based flow meter when the measured flow rate is relatively low, and as a function of the flow rate as measured by the pressure-based flow meter when the flow rate is relatively high. A comparison of the flow measurements of the two flow meters can be used to (a) sense pressure disturbances at low flow rates, and (b) sense when the thermal-based flow meter is out of calibration so that a zero offset signal can be applied to the thermal-based flow meter.