Fluid flow controller and method of operation

Patent 6539968 Issued on April 1, 2003. Estimated Expiration Date:

September 20, 2020. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

2666297

3271994

3335748

3559482

3570807

3807456

3814541

3841520

3910113

Constant flow valve for low flow rates
Patent #: 4015626
Issued on: 04/05/1977
Inventor: Thordarson

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Inventors

Application

No. 666039 filed on 09/20/2000

US Classes:

137/10, By speed of fluid73/861.52, With restriction137/486, Responsive to change in rate of fluid flow137/487.5, Electrically actuated valve138/44, Central path251/118WITH MATERIAL GUIDE OR RESTRICTOR

Examiners

Primary: Buiz, Michael
Assistant: Krishnamurthy, Ramesh

Attorney, Agent or Firm

Foreign Patent References

0468793 EP. 01/13/1992
0689040 EP. 12/13/1995
WO 87/00267 WO. 01/13/1987

International Class

G05D 007/06

Abstract

A fluid mass flow controller, particularly adapted for controlling mass flow rates of toxic and reactive gases used in semiconductor device fabrication, includes a control circuit connected to pressure sensors for sensing the differential pressure across a flow restrictor in the mass flow controller for controlling a valve to control the fluid mass flow rate to a setpoint. The control circuit compares the differential pressure with the downstream pressure at a measured temperature with a data set of a gas passing through the flow controller for a range of differential pressures and downstream pressures and adjusts the flow control rate accordingly. The flow controller is mechanically uncomplicated including a two part body for supporting the pressure sensors, a remotely controllable flow control valve and the flow restrictor. The flow restrictor may comprise an orifice or nozzle but preferably comprises a sintered metal plug having a predetermined porosity for the expected materials and flow conditions to which the flow controller will be exposed. Process gases to be controlled by the flow controller are tested to provide data sets of mass flow rates at selected temperatures for a range of differential pressures across a flow restrictor and a range of downstream pressures.

Other References

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