System and method for improving the accuracy of a rate of decay (ROD) measurement in a mass flow controller

Patent metadata

Field	Value
Publication number	US-9810377-B2
Application number	US-201314378539-A
Country	US
Kind code	B2
Filing date	Mar 4, 2013
Priority date	Mar 7, 2012
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

A mass flow controller includes at least one conduit having a fluid inlet and a fluid outlet, the conduit defining a flow path along which the fluid flows. The mass flow controller also includes a modified inlet block having an inlet aperture, an inlet channel, and a reservoir fluidly coupled to the inlet channel and the conduit that enhances flow through the controller and improves rate-of-decay measurements. The mass flow controller includes at least one flow sensor that generates a flow sensor signal that is proportional to the mass flow rate of the fluid through the conduit. The mass flow controller includes a control subsystem coupled to a flow sensor and a valve assembly to control flow through the conduit.

First claim

What is claimed:

1. A system for determining a flow rate of a compressible fluid, the system comprising:
an upstream isolation valve, a conduit comprising a fluid inlet and a fluid outlet, the conduit defining a flow path along which the fluid flows;
a mass flow controller located downstream from the upstream isolation valve along the conduit;
an inlet block of the mass flow controller, the inlet block comprising an inlet passage, an inlet channel, and a reservoir comprising one or more chambers that are fluidly coupled to the inlet channel upstream from a location at which the inlet channel is fluidly coupled to a bypass of the conduit, wherein the reservoir is sized and configured, based on operating conditions, to enable a rate of decay measurement to be performed on the system without interrupting the flow of fluid delivered to the fluid outlet, and wherein the inlet block is formed from a single piece of material;
wherein filler material is disposed within the reservoir;
at least one pressure sensor that generates a pressure sensor signal that is indicative of the pressure of the fluid within the conduit, the at least one pressure sensor being coupled to a controller that is operable to generate a pressure sensor based pressure measurement for the fluid, the pressure sensor based pressure measurement being determined at least in part from the pressure sensor signal; and
at least one flow sensor that generates a sensor signal that is indicative of a flow rate of the fluid through the conduit, the at least one flow sensor being coupled to a controller that is operable to generate a flow sensor based flow rate for the fluid, the sensor based flow rate being determined at least in part from the flow sensor signal.

2. The system for determining a flow rate of a compressible fluid of claim 1 , wherein the reservoir comprises a hollowed area adjacent the inlet channel.

3. The system for determining a flow rate of a compressible fluid of claim 2 , wherein the hollowed area is oval.

4. The system for determining a flow rate of a compressible fluid of claim 1 , wherein the reservoir comprises a plurality of chambers.

5. The system for determining a flow rate of a compressible fluid of claim 4 , wherein the plurality of chambers are arranged in series to define a fluid flow path.

6. The system for determining a flow rate of a compressible fluid of claim 4 , wherein the plurality of chambers comprises one or more tubes.

7. A method of manufacturing a mass flow controller, the method comprising:
providing a block to secure components of the mass flow controller;
forming a conduit comprising a fluid inlet and a fluid outlet to define a fluid flow path;
providing an inlet block comprising an inlet passage, an inlet channel fluidly coupled to the fluid inlet, and a reservoir fluidly coupled to the inlet channel upstream from a location at which the inlet channel is fluidly coupled to a bypass of the conduit, wherein the reservoir is sized and configured, based on operating conditions, to enable a rate of decay measurement to be performed without interrupting the flow of fluid to the fluid outlet, and wherein the inlet block is formed from a single piece of material;
providing filler material within the reservoir;
providing at least one flow sensor that generates a flow sensor signal proportional to the flow rate of fluid through the conduit;
providing at least one pressure sensor that generates a pressure sensor signal that is indicative of the pressure of the fluid within the conduit, coupling the at least one flow sensor and the at least one pressure sensor to a control subsystem that is operable to
receive the flow sensor signal and generate a flow sensor based flow rate for the fluid;
and coupling a valve assembly to the block and establishing a communicative coupling between the control subsystem and the valve assembly, wherein the control subsystem is operable to control the valve assembly to adjust the rate of fluid through the conduit.

8. The method of claim 7 , wherein the reservoir comprises a hollowed area adjacent the inlet channel.

9. The method of claim 8 , wherein the hollowed area is oval in cross-section.

10. The method of claim 7 , wherein the reservoir comprises a plurality of chambers.

11. The method of claim 10 , wherein the plurality of chambers comprise tubes.

12. A mass flow controller, comprising:
at least one conduit comprising a fluid inlet and a fluid outlet, the conduit defining a flow path along which the fluid flows;
an inlet block comprising an inlet passage, an inlet channel, and a reservoir fluidly coupled to the inlet channel upstream from a location at which the inlet channel is fluidly coupled to a bypass of the conduit, wherein the reservoir is configured, based on the operating conditions of the fluid, to facilitate a rate of decay measurement of the pressure of the fluid within the conduit while the mass flow controller is operational, and wherein the inlet block is formed from a single piece of material;
wherein filler material is disposed within the reservoir;
at least one pressure sensor that generates a pressure sensor signal that is indicative of the pressure of the fluid within the conduit, the at least one pressure sensor being coupled to a controller that is operable to generate a pressure sensor based pressure
measurement for the fluid, the pressure sensor based pressure measurement being determined at least in part from the pressure sensor signal;
at least one flow sensor that generates a flow sensor signal indicative of a flow rate of the fluid through the conduit, the at least one flow sensor being coupled to a controller that is operable to generate a flow sensor based flow rate for the fluid, the flow sensor based flow rate being determined at least in part from the flow sensor signal;
a control subsystem coupled to the at least one flow sensor; and
a valve assembly communicatively coupled to the control subsystem and operable to adjust the rate of fluid through the conduit.

13. The mass flow controller of claim 12 , wherein the reservoir comprises a hollowed area adjacent the inlet channel.

14. The mass flow controller of claim 12 , wherein the reservoir comprises a chamber.

15. The mass flow controller of claim 12 , wherein the reservoir comprises a plurality of chambers.

16. The mass flow controller of claim 15 , wherein the plurality of chambers are arranged in series to define a fluid flow path.

17. The mass flow controller of claim 15 , wherein the inlet block is formed from a material selected from the group consisting of stainless steel, high performance alloy, a ceramic, and a plastic.

Assignees

• Illinois Tool Works

Inventors

• Kehoe Anthony
• Lull John
• Valentine Bill
• Ellec Chris

Classifications

• G05D7/0635

  by action on throttling means (G05D7/0688, G05D7/0694 take precedence) · CPC title

• F17D5/00 Primary

  Protection or supervision of installations (arrangements for protecting foundations E02D31/00; protecting pipes from damage or internal or external wear F16L57/00, against corrosion and scale F16L58/00; investigation of the fluid-tightness of structures G01M3/00) · CPC title

• Y10T137/7784

  Responsive to change in rate of fluid flow · CPC title

• Y10T137/8175

  Plural · CPC title

• G01F1/6965 Primary

  comprising means to store calibration data for flow signal calculation or correction · CPC title