Apparatus and method for mass flow controller with a plurality of closed loop control code sets

• US 6,868,862 B2
• Filed: 06/24/2002
• Issued: 03/22/2005
• Est. Priority Date: 06/24/2002
• Status: Expired due to Term

• Current Assignee: MKS Instruments Incorporated
• Original Assignee: MKS Instruments Incorporated
• Inventors: Shajii, Ali, Ambrosina, Jesse, Kottenstette, Nicholas
• Primary Examiner(s): Scherbel, David A.
• Assistant Examiner(s): Krishnamurthy, Ramesh
• Application Number:
  US10/178,261
• Publication Number:
  US 20030234044A1
• Time in Patent Office: 1,002 Days
• Field of Search: 700/2, 700/3, 700/4, 700/5, 700/6, 700/282, 73/11.6, 73/13.5, 732/025, 137/486, 137/487.5, 702/45, 702/100
• US Class Current: 137/487.5
• CPC Class Codes: G01F 1/684 Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
• CPC Class Codes: G01F 1/6965 comprising means to store calibration data for flow signal calculation or correction
• CPC Class Codes: G01F 1/86 Indirect mass flowmeters, e.g. measuring volume flow and density, temperature or pressure
• CPC Class Codes: G01F 25/15 specially adapted for gas meters G01F25/11 - G01F25/14, G01F25/17 take precedence
• CPC Class Codes: G01F 5/00 Measuring a proportion of the volume flow
• CPC Class Codes: G05D 7/0635 by action on throttling means G05D7/0688, G05D7/0694 take precedence
• CPC Class Codes: Y10T 137/7759 Responsive to change in rate of fluid flow
• CPC Class Codes: Y10T 137/7761 Electrically actuated valve

Abstract

A mass flow controller includes an electronic controller for which a plurality of closed loop control codes sets may be uploaded. In a dual processor embodiment, one processor may upload a plurality of codes sets for another, with the selection of codes sets determined by the uploading processor either autonomously or through user interaction.

Claims

1. A mass flow controller comprising:

a mass flow sensor configured to produce a mass flow signal representative of a gas flow through the mass flow controller; and

an electronic controller configured to produce a closed loop control signal for an outlet control valve, based on said mass flow signal, wherein said electronic controller is also configured to upload a plurality of executable closed-loop code sets, the electronic controller includes a dual-processor having a processor configured to operate in a deterministic mode, wherein the deterministic mode includes being configured to produce said closed loop control signal for the outlet control valve, and a processor configured to operate in a non-deterministic mode, wherein the non-deterministic mode includes being configured to upload said plurality of executable code sets, to select one of said executable code sets and to pass the selected code set to the deterministic processor for the processor to execute.

2. The mass flow controller of claim 1 wherein one or more executable code sets includes code for executing a diagnostic mode of operation.

3. The mass flow controller of claim 1 wherein one or more executable code sets includes code for executing a calibration mode of operation.

4. The mass flow controller of claim 1 wherein the mass flow sensor is a thermal mass flow sensor, including a sensor bypass, configured to sense the flow of fluid into the inlet of the controller.

5. The mass flow controller of claim 4 further comprising:

a pressure sensor configured to sense the fluid pressure in the volume between the thermal mass flow sensor bypass and the control valve.

6. The mass flow controller of claim 1 wherein the deterministic processor is configured to acquire a pressure signal produced by said pressure sensor and to compensate the sensed inlet flow rate sensed by said mass flow sensor using the pressure signal to thereby produce a compensated measure of the rate of fluid flow out of the controller.

7. The mass flow controller of claim 6 wherein the deterministic processor is configured to compute the time rate of change of pressure within the volume between the sensor bypass and the outlet control valve, and to use this time rate of change of pressure to produce the compensated measure of the rate of fluid flow out of the controller.

8. The mass flow controller of claim 7 wherein the deterministic processor is configured to compare the compensated measure of the rate of fluid flow out of the controller to a set value and to adjust the outlet control valve to minimize the difference between the set value and the compensated measure of the rate of fluid flow out of the controller.

9. The mass flow controller of claim 8 wherein the deterministic processor is configured to compensate the controller'"'"'s sensed in flow rate, Qi, by calculating the compensated sensed inlet flow rate, Qo, according to:

Qo=Qi−

C1(V/T)(dP/dt), where;

Qo=the compensated sensed inlet flow rate, Qi=the sensed inlet flow rate, C1=a normalizing constant, V=the volume between the sensor bypass and the outlet flow control valve, T=the temperature of the fluid within the volume, C1 is the resultant of the temperature at standard temperature and pressure divided by the pressure at standard temperature and pressure, and (dP/dt)=time rate of change of pressure within the volume.

10. The mass flow controller of claim 1 wherein the deterministic processor is a digital signal processor (DSP).

11. The mass flow controller of claim 10 further comprising an inter-processor interface configured for communication between said deterministic and non-deterministic processors.

12. The mass flow controller of claim 11 wherein the inter-processor interface is dual-ported memory with one or more locations arranged as mailboxes for the processors.

13. The mass flow controller of claim 1 wherein the non-deterministic processor is configured to provide a user interface to the mass flow controller.

14. The mass flow controller of claim 13 wherein the non-deterministic processor includes a network interface.

15. The mass flow controller of claim 14 wherein the network interface includes a web server.

16. The mass flow controller of claim 15 wherein the non-deterministic processor is configured to set up diagnostics through the network interfaces and exchange diagnostic information with the deterministic processor through the inter-processor interface and the deterministic processor is responsive to commands from the non-deterministic processor to perform diagnostic operations.

17. The mass flow controller of claim 16 wherein the deterministic processor is configured to run on-line diagnostics.

18. The mass flow controller of claim 16 wherein the network interface includes a web server and the web server is configured to set up said diagnostics.

19. The mass flow controller of claim 1 wherein the mass flow sensor is a thermal mass flow sensor, including a sensor bypass, configured to sense the flow of fluid into the inlet of the controller and the mass flow controller further comprising:

a mass flow calibrator operative to produce an electronic signal representative of mass flow in the mass flow controller independent of the mass flow sensor flow signal; and

an electronic controller configured to correlate the mass flow signal from the thermal mass flow sensor to that of the mass flow calibrator.

20. The mass flow controller of claim 19 wherein the mass flow calibrator comprises:

a variable flow gas source;

a receptacle of predetermined volume configured to receive gas from the variable flow gas source, the variable flow gas source configured to provide proportionate flow to the mass flow sensor and to the receptacle; and

a pressure differentiator configured to produce an electronic signal representative of the time derivative of gas pressure within the receptacle of predetermined volume, said time derivative signal being proportional to the mass flow signal of the mass flow calibrator.

21. The mass flow controller of claim 20 wherein the differentiator includes:

a pressure transducer configured to produce an electronic signal representative of the pressure within the receptacle;

analog differentiator circuitry configured to produce an electronic signal that is representative of the time derivative of said electronic signal representative of the pressure within the receptacle; and

an analog to digital converter configured to convert one or more values of the analog time derivative signal to digital samples of the time derivative.

22. The mass flow controller of claim 1 wherein the deterministic processor is configured to acquire one or more sensor readings.

23. The mass flow controller of claim 22 wherein the deterministic processor is configured to acquire temperature readings from a temperature sensor.

24. The mass flow controller of claim 1 further comprising one or more diagnostic outputs, wherein said deterministic processor is configured to drive at least one of said diagnostic outputs.

25. The mass flow controller of claim 1 further comprising one or more diagnostic inputs, wherein said deterministic processor is configured to read at least one of said diagnostic inputs.

26. The mass flow controller of claim 13 wherein the user interface includes a display.

27. The mass flow controller of claim 13 wherein said user interface includes an input device.

28. The mass flow controller of claim 1 wherein the non-deterministic processor is configured to provide a communications interface.

29. The mass flow controller of claim 28 wherein the communications interface is a Device Net communications interface.

30. The mass flow controller of claim 14 wherein the network interface is an Ethernet network interface.

31. The mass flow controller of claim 19 further comprising:

a valve operative to control the flow of gas in the mass flow controller under control of the electronic controller.

32. The mass flow controller of claim 19 wherein the deterministic processor is configured to employ the correlated mass flow sensor signal to control the outlet valve during non-calibration operation.

33. The mass flow controller of claim 20 wherein the gas flow is configured to supply the same gas at the same flow rate to both the mass flow sensor and the receptacle of predetermined volume.

34. The mass flow controller of claim 29 further comprising:

storage for storing one or more samples of the signal representative of the time derivative of gas pressure.

35. The mass flow controller of claim 1 wherein said electronic controller is configured to provide a network interface that permits the execution of mass flow controller active diagnostics.

36. The mass flow controller of claim 35 wherein active diagnostics code operational with the mass flow controller'"'"'s electronic controller includes code to enable the manipulation of operational signals.

37. The mass flow controller of claim 35 wherein active diagnostics code operational with the mass flow controller'"'"'s electronic controller includes code to enable the manipulation of diagnostic signals.

38. The mass flow controller of claim 35 wherein active diagnostics code operational with the mass flow controller'"'"'s electronic controller includes code to enable the monitoring of operational signals.

39. The mass flow controller of claim 35 wherein active diagnostics code operational with the mass flow controller'"'"'s electronic controller includes code to enable the monitoring of diagnostic signals.

40. The mass flow controller of claim 35 wherein on-line diagnostics code operational with the mass flow controller'"'"'s electronic controller enables on-line monitoring of operational signals.

41. The mass flow controller of claim 35 wherein on-line diagnostics code operational with the mass flow controller'"'"'s electronic controller enables on-line monitoring of diagnostic signals.

42. The mass flow controller of claim 35 wherein on-line diagnostics code operational with the mass flow controller'"'"'s electronic controller enables on-line manipulation of diagnostic signals.

43. The mass flow controller of claim 35 wherein on-line diagnostics code operational with the mass flow controller'"'"'s electronic enables on-line manipulation of operational signals.

44. The mass flow controller of claim 14 wherein the network interface comprises a web server that enables a web-enabled device connected to the world wide web to execute on-line diagnostics from the web-enabled device.

45. The mass flow controller of claim 1 wherein the mass flow controller is self-calibrating.