Methods and apparatus for multiple channel mass flow and ratio control systems

Patent metadata

Field	Value
Publication number	US-10698426-B2
Application number	US-201815973190-A
Country	US
Kind code	B2
Filing date	May 7, 2018
Priority date	May 7, 2018
Publication date	Jun 30, 2020
Grant date	Jun 30, 2020

Abstract

Fluid control systems, including mass flow control systems, mass flow ratio control systems, and mass flow and ratio control systems, as well as corresponding methods for fluid control are provided. These systems allow one shared pressure sensor to be used for multiple flow channels, and a controller which can accurately determine mass flow on the basis of fluid pressure detected by this shared pressure sensor.

First claim

What is claimed is:

1. A fluid control system comprising:
a plurality of flow channels carrying fluids, each flow channel comprising a flow restrictor, a flow regulating valve and a channel pressure sensor between the flow restrictor and the flow regulating valve;
a shared flow channel carrying the fluids to or from the plurality of flow channels, the flow restrictor in each flow channel being between the channel pressure sensor and the shared flow channel;
a shared pressure sensor in the shared flow channel configured to detect a shared flow channel pressure; and
a controller that determines mass flow through each of the flow channels based on channel pressures and the shared flow channel pressure and controls the flow regulating valves of the flow channels to control mass flow through each flow channel, wherein the controller determines through recursive calculation (1) channel pressures for positions that are adjacent to the flow restrictors and opposite to the channel pressure sensors of the plurality of flow channels, (2) mass flow through each flow channel, and (3) total mass flow through the shared channel.

2. The fluid control system of claim 1 , wherein the controller determines mass flow through each flow channel based on property of the fluid flowing therethrough, property of the flow restrictor, and flow channel property between the flow restrictor and the shared pressure sensor.

3. The fluid control system of claim 2 , wherein the controller determines mass flow through a flow channel of the plurality of flow channels by (i) assuming a flow channel pressure adjacent to the flow restrictor and opposite to the channel pressure sensor of the flow channel, the channel pressure sensor providing a detected flow channel pressure, (ii) determining the mass flow through the flow channel based on the flow channel pressure adjacent to the flow restrictor and opposite to the channel pressure sensor and the detected flow channel pressure for the flow channel, (iii) determining total mass flow on the basis of mass flows through each of the flow channels of the plurality of flow channels, (iv) calculating the flow channel pressure adjacent to the flow restrictor and opposite to the channel pressure sensor of the flow channel using the total mass flow determined in step (iii), and repeating steps (ii) to (iv).

4. The fluid control system of claim 3 , wherein the shared flow channel is downstream from the plurality of flow channels.

5. The fluid control system of claim 4 , wherein the shared flow channel is upstream from the plurality of flow channels.

6. The fluid control system of claim 4 , further comprising a second plurality of flow channels, each flow channel of the second plurality of flow channels comprising a flow restrictor, a flow regulating valve and a channel pressure sensor between the flow restrictor and the flow regulating valve;
the shared flow channel carrying fluids from the plurality of flow channels to the second plurality of flow channels;
for each flow channel of the second plurality of flow channels, the flow restrictor being between the channel pressure sensor and the shared flow channel; wherein the controller further determines mass flow through each of the flow channels of the second plurality of flow channels based on channel pressures and the shared flow channel pressure and controls the flow regulating valves of the flow channels to control mass flow through each flow channel.

7. The fluid control system of any claim 6 , wherein the plurality of flow channels and the second plurality of flow channels are part of an integrated system.

8. The fluid control system of claim 7 , wherein the shared pressure sensor is not part of the integrated system.

9. The fluid control system of claim 4 , wherein the controller calculates a flow channel pressure adjacent to a flow restrictor and opposite to a channel pressure sensor of an i-th flow channel, the i-th flow channel being upstream from the shared flow channel, using Equation (1): P d,i =ƒ pd (P d ,Q t , V i ,L i ) (1); where ƒ Pd is a function of downstream pressure P d detected by the shared pressure sensor, total flow through the shared flow channel Q t , and volume V i and length L i of the i-th flow channel from its restrictor to the shared pressure sensor.

10. The fluid control system of claim 9 , wherein ƒ Pd is provided by Equation (2): ƒ Pd (P d ,Q t , V i ,L i )=k i,1 ·P d +k i,2 ·Q t +k i,3 ·V i +k i,4 ·L i (2); where k i,1 , k i,2 , k i,3 and k i,4 are empirically or experimentally obtained linear coefficients.

11. The fluid control system of claim 4 , wherein the controller calculates a flow channel pressure adjacent to a flow restrictor and opposite to a channel pressure sensor of a j-th flow channel using Equation (6): P u,j =ƒ Pu (P u ,Q t , V j ,L j ) (6); where ƒ Pu is a function of upstream pressure P u detected by the shared pressure sensor, total flow through the shared flow channel Q t , and volume V j and length L j of the j-th flow channel from its restrictor to the shared pressure sensor.

12. The fluid control system of claim 11 , wherein ƒ Pu is provided by Equation ƒ Pu (P u ,Q t , V j ,L j )=k j,1 ·P u +k j,2 ·Q t +k j,3 ·V j +k j,4 ·L j (7); where k j,1 , k j,2 , k j,3 and k j,4 are empirically or experimentally obtained linear coefficients.

13. A fluid control method, comprising:
flowing fluids through a plurality of flow channels, each flow channel comprising a flow restrictor and a flow regulating valve;
flowing the fluids to or from the plurality of flow channels through a shared flow channel;
detecting a shared flow channel pressure in the shared flow channel;
detecting a flow channel pressure for each flow channel between its flow regulating valve and its flow restrictor;
determining mass flow through each of the flow channels based on the flow channel pressures and the shared flow channel pressure by recursively calculating (1) mass flow through each flow channel, (2) channel pressures for positions that are adjacent to the flow restrictors and opposite to the channel pressure sensors of the plurality of flow channels, and (3) total mass flow through the shared channel; and
controlling the flow regulating valves of the flow channels to control mass flow through each flow channel.

14. The fluid control method of claim 13 , wherein mass flow through each flow channel is determined based on property of the fluid flowing therethrough, property of the flow restrictor, and flow channel property between the flow restrictor and where the shared flow channel pressure is detected.

15. The fluid control method of claim 13 , wherein determining mass flow through a flow channel of the plurality of flow channels comprises (i) assuming a flow channel pressure adjacent to the flow restrictor and opposite to the channel pressure sensor of the flow channel, (ii) determining the mass flow through the flow channel based on the flow channel pressure adjacent to the flow restrictor and opposite to the channel pressure sensor and the detected flow channel pressure for the flow channel, (iii) determining total mass flow on the basis of mass flows through each of the flow channels of the plurality of flow channels, (iv) calculating the flow channel pressure adjacent to the flow restrictor and opposite to the channel pressure sensor of the flow channel using the total mass flow determined in step (iii), and repeating steps (ii) to (iv).

16. The fluid control method of claim 13 , further comprising flowing fluids from the plurality of flow channels through the shared channel and into a second plurality of f

Assignees

• Mks Instr Inc

Inventors

• Ding Junhua
• L'Bassi Michael
• Cole Wayne

Classifications

• G05D7/0664 Primary

  the plurality of throttling means being arranged for the control of a plurality of diverging flows from a single flow (G05D7/0652 takes precedence; ratio control G05D11/13) · CPC title

• G05D7/0658 Primary

  the plurality of throttling means being arranged for the control of a single flow from a plurality of converging flows (G05D7/0652 takes precedence; ratio control G05D11/13) · CPC title

• G05D11/139

  by measuring a value related to the quantity of the individual components and sensing at least one property of the mixture · CPC title

• G05D7/0652 Primary

  the plurality of throttling means being arranged in parallel · CPC title

• G01F5/005

  by measuring pressure or differential pressure, created by the use of flow constriction · CPC title