System and method for control of fluid pressure

• US 20070128046A1
• Filed: 12/02/2005
• Published: 06/07/2007
• Est. Priority Date: 12/02/2005
• Status: Active Grant

• Current Assignee: Entegris Incorporated
• Original Assignee: Entegris Incorporated
• Inventors: Cedrone, James, Gonnella, George
• Granted Patent: US 7,850,431 B2
• Time in Patent Office: Days
• US Class Current: 417/2
• CPC Class Codes: F04B 1/08 regulated by delivery pressure
• CPC Class Codes: F04B 2203/0209 Rotational speed
• CPC Class Codes: F04B 2205/03 Pressure in the compression chamber
• CPC Class Codes: F04B 2205/04 Pressure in the outlet chamber
• CPC Class Codes: F04B 23/04 Combinations of two or more pumps
• CPC Class Codes: F04B 23/06 the pumps being all of reciprocating positive-displacement type
• CPC Class Codes: F04B 41/06 Combinations of two or more pumps
• CPC Class Codes: F04B 43/088 with two or more tubular flexible members in series F04B43/1133 takes precedence
• CPC Class Codes: F04B 49/065 and making use of computers
• CPC Class Codes: F04B 49/08 Regulating by delivery pressure
• CPC Class Codes: F04B 49/103 Responsive to speed
• CPC Class Codes: F04B 51/00 Testing machines, pumps, or pumping installations

Abstract

Embodiments of the present invention are related to a pumping system that accurately dispenses fluid using a multiple stage (“multi-stage”) pump. More particularly, embodiments of the present invention provide for control of a feed stage pump to regulate fluid pressure at a downstream dispense stage pump. According to one embodiment of the present invention, a pressure sensor at the dispense stage pump determines the pressure in a dispense chamber. When the pressure reaches a predefined threshold, the dispense stage pump can begin to increase the available volume of the dispense chamber, thereby causing the pressure in the dispense chamber to drop. As the pressure decreases/increases at the downstream pump, the pressure applied by the upstream pump can bed increased/decreased.

Claims

1. A system for controlling fluid pressure in a pump comprising:

a first stage pump;

a second stage pump in fluid communication with and downstream of the first stage pump;

a pressure sensor to measure the pressure of a fluid at the second stage pump;

a pump controller to control fluid pressure at the second stage pump by adjusting the operation of the first pump, the pump controller coupled to the first stage pump;

second stage pump and pressure sensor, the pump controller operable to;

receive pressure measurements from the pressure sensor; and

if a pressure measurement from the pressure sensor indicates that the pressure at the second stage pump has reached a first predefined threshold, cause the first stage pump to assert less pressure on the fluid.

2. The system of claim 1, wherein pump controller is further operable to:

cause the first pump to assert more pressure on the fluid if the a pressure measurement from the pressure sensor indicates the pressure at the second stage pump has fallen below a second predefined threshold.

3. The system of claim 2, wherein the first predefined threshold is a maximum pressure threshold and the second predefined threshold is a minimum pressure threshold.

4. The system of claim 2, wherein the first pump asserts more pressure by increasing the speed of a first pump motor and asserts less pressure by decreasing the speed of the first pump motor.

5. The system of claim 2, wherein the controller is further operable to:

cause the second stage pump to retract at a constant rate when a pressure measurement from the pressure indicates that the fluid pressure has reached an initial threshold.

6. The system of claim 1, wherein the first predefined threshold is a set point.

7. The system of claim 6, wherein the pump controller is further operable to cause the first pump to assert more pressure on the fluid if a pressure measurement from the pressure sensor indicates that the fluid pressure is below the set point.

8. The system of claim 7, wherein the first pump asserts more pressure on the fluid by increasing the speed of a first pump motor and asserts less pressure on the pressure on the fluid by decreasing the speed of the first pump motor.

9. The system of claim 7, wherein the pump controller is further operable to cause the second stage pump to retract at a constant rate when a pressure measurement from the pressure sensor indicates that the fluid pressure has reached the set point.

10. The system of claim 1, further comprising a filter located between the first pump and the second pump.

11. A method for controlling fluid pressure of a dispense pump in multi-stage pump, comprising:

applying pressure to a fluid at a feed pump;

determining a fluid pressure at a dispense pump downstream of the feed pump;

if the fluid pressure at the dispense pump reaches predefined maximum pressure threshold, decreasing pressure on the fluid at the feed pump; and

if the fluid pressure at the dispense pump is below a predefined minimum pressure threshold, increasing pressure on the fluid at the feed pump.

12. The method of claim 11, wherein increasing pressure on the fluid comprises increasing a feed motor speed and decreasing pressure on the fluid comprises decreasing the feed motor speed.

13. The method of claim 11, wherein the feed pump increases and decreases pressure on the fluid to maintain and approximately constant pressure at the dispense pump for a period of time.

14. The method of claim 11, wherein the maximum pressure threshold and minimum pressure threshold are equal to a set point.

15. The method of claim 14, further comprising:

determining that the fluid pressure at the dispense pump has reached the set point; and

increasing the available volume for fluid at the dispense pump at a constant rate.

16. The method of claim 11, further comprising stopping the feed pump and the dispense pump when the dispense pump reaches a home position.

A computer program product comprising a set of computer instructions stored on one or more computer readable media, said set of computer instructions further comprising instructions executable by one or more processors to:

receive pressure measurements from the pressure sensor; and

compare the pressure measurements to the first predefined threshold;

if a pressure measurement from the pressure sensor indicates that the pressure at the second stage pump has reached a first predefined threshold, direct the first stage pump to assert less pressure on the fluid.

17. The computer program product of claim 17, wherein said set of computer instructions further comprise instructions executable to direct the first pump to assert more pressure on the fluid if the a pressure measurement from the pressure sensor indicates the pressure at the second stage pump has fallen below a second threshold.

21. The computer program product of claim 17, wherein the first predefined threshold is a set point.

18. The computer program product of claim 18, wherein the first predefined threshold is a maximum pressure threshold and the second predefined threshold is a minimum pressure threshold.

19. The computer program product of claim 18, wherein the first pump asserts more pressure by increasing the speed of a first pump motor and asserts less pressure by decreasing the speed of the first pump motor.

20. The computer program product of claim 18, wherein the set of computer instructions further comprise instructions executable to:

direct the second stage pump to retract at a constant rate when a pressure measurement from the pressure indicates that the fluid pressure has reached an initial threshold.

22. The computer program product of claim 22, wherein the set of computer instructions further comprise instructions executable to direct the first pump to assert more pressure on the fluid if a pressure measurement from the pressure sensor indicates that the fluid pressure is below the set point.

24. The computer program product of claim 22, wherein the set of computer instructions further comprise instructions executable to direct the second stage pump to retract at a constant rate when a pressure measurement from the pressure sensor indicates that the fluid pressure has reached the set point.

23. The computer program product of claim 23, wherein the first pump asserts more pressure on the fluid by increasing the speed of a first pump motor and asserts less pressure on the pressure on the fluid by decreasing the speed of the first pump motor.

25. A multiple stage dispense pump comprising:

a feed pump further comprising;

a feed chamber;

a feed diaphragm in the feed chamber;

a feed piston in contact with the feed diaphragm to displace the feed diaphragm;

a feed lead screw coupled to the feed piston;

a feed motor coupled to the feed lead screw to impart rotation to the feed lead screw to cause the feed piston to move;

a filter in fluid communication with the feed chamber;

an isolation valve between the feed pump and the filter to allow or restrict fluid flow from the feed chamber to the filter;

a dispense pump in fluid communication with the filter, the dispense pump further comprising;

a dispense chamber;

a dispense diaphragm in the dispense chamber;

a dispense piston in contact with the dispense diaphragm to displace the dispense diaphragm;

a dispense lead crew coupled to the dispense piston to displace, the dispense piston in the dispense chamber;

a dispense lead screw coupled to the dispense piston;

a dispense motor coupled to the dispense lead screw to impart rotation to the dispense lead screw to cause the dispense piston to move;

a barrier valve between the filter and the dispense pump to allow or restrict fluid flow from the filter to the dispense chamber

a pressure sensor exposed to the dispense chamber to measure a fluid pressure in the dispense chamber; and

a controller connected to the pressure sensor, feed motor and dispense motor, the controller, during a filtration segment in which both the isolation valve and barrier valve are open, is operable to;

receive pressure measurements from the pressure sensor;

when a pressure measurement indicate that the pressure of a fluid in the dispense chamber has initially reached a set point, direct the dispense motor to operate at an approximately constant rate to retract the dispense piston; and

for a subsequent pressure measurement, direct the feed motor to operate at a decreased speed if the subsequent pressure measurement indicates that the pressure of the fluid in the dispense chamber is below the set point and direct the feed motor to operate at an increased speed if the subsequent pressure measurement is above the set point;

wherein the multiple stage pump is adapted for use with semiconductor manufacturing process fluids.

26. The multiple stage pump of claim 26, wherein the controller is further operable to direct the feed motor and dispense motor to stop when the dispense motor reaches a home position.