Hydraulic amplifier pump for use in ultrahigh pressure liquid chromatography

• US 20030118459A1
• Filed: 12/21/2001
• Published: 06/26/2003
• Est. Priority Date: 12/21/2001
• Status: Active Grant

• Current Assignee: Waters Technologies Corporation (Waters Corporation)
• Original Assignee: Waters Investments Limited (Waters Corporation)
• Inventors: Gerhardt, Geoff C., Compton, Bruce J.
• Granted Patent: US 6,712,587 B2
• Time in Patent Office: Days
• US Class Current: 417/390
• CPC Class Codes: F04B 13/00 Pumps specially modified to deliver fixed or variable measured quantities
• CPC Class Codes: F04B 23/06 the pumps being all of reciprocating positive-displacement type
• CPC Class Codes: F04B 49/065 and making use of computers
• CPC Class Codes: F04B 9/113 reciprocating movement of the pumping members being obtained by a double-acting liquid motor
• CPC Class Codes: F04B 9/1174 with fluid-actuated inlet or outlet valve mechanically controlled F04B7/00
• CPC Class Codes: F04B 9/1178 the movement in the other direction being obtained by a hydraulic connection between the liquid motor cylinders
• CPC Class Codes: G01N 2030/324 speed, flow rate
• CPC Class Codes: G01N 2030/326 pumps
• CPC Class Codes: G01N 30/22 in high pressure liquid systems
• CPC Class Codes: G01N 30/32 of pressure or speed G01N30/36 takes precedence
• CPC Class Codes: G01N 30/34 of fluid composition, e.g. gradient G01N30/36 takes precedence
• CPC Class Codes: G01N 30/36 in high pressure liquid systems

Abstract

A hydraulic amplifier system for an ultra-high pressure liquid chromatography system. The hydraulic amplifier system includes a hydraulic cylinder comprising a primary piston chamber in which a primary piston is disposed and a secondary piston chamber in which a secondary piston is disposed. The cross-sectional area of the primary piston is larger than the cross-sectional area of the secondary piston. The difference in the cross-sectional areas of the pistons creates an amplification of the pressure in the primary piston chamber and a reduction in flow rate.

Claims

1. A hydraulic amplifier system for supplying solvent to a chromatographic system comprising:

a hydraulic cylinder which supplies pressurized solvent to said chromatographic system; and

a pump which supplies pressurized hydraulic fluid to actuate said hydraulic cylinder.

2. The hydraulic amplifier system of claim 1, wherein said hydraulic cylinder supplies solvent to said chromatographic system at a substantially constant flow rate.

3. The hydraulic amplifier system of claim 1, wherein said hydraulic cylinder comprises:

an inlet chamber;

an outlet chamber;

a primary piston disposed in said inlet chamber, said primary piston being driven by said pressurized hydraulic fluid;

a secondary piston disposed in a secondary piston chamber, said secondary piston being activated by said primary piston;

wherein a cross-sectional area of said primary piston is larger than a cross-sectional area of said secondary piston, such that a pressure in said secondary piston chamber is greater than a pressure in said inlet chamber, and a flow rate through said secondary piston chamber is less than a flow rate through said outlet chamber.

4. The hydraulic amplifier system of claim 3, wherein a ratio of said cross-sectional area of said primary piston to said cross-sectional area of said secondary piston is at least 4:

1.

5. The hydraulic amplifier system of claim 3, further including a linear position transducer 14 which measures the position of said primary piston and said secondary piston.

6. The hydraulic amplifier system of claim 3, further including a multiple port valve which regulates flow to said primary piston, thereby controlling said primary piston operates in one of a pump mode and a refill mode.

7. The hydraulic amplifier system of claim 3, further including a first pressure transducer which measures pressure in an inlet chamber of said hydraulic cylinder and a second pressure transducer which measures pressure in an outlet chamber of said hydraulic cylinder, wherein measurements of said first pressure transducer and said second pressure transducer are used to compute a pressure difference across said primary piston and said pressure in said secondary piston.

8. The hydraulic amplifier system of claim 1, further including a system controller for controlling said hydraulic amplifier system.

9. The hydraulic amplifier system of claim 1, further including an outlet check valve which regulates the supply of solvent to said chromatographic system.

10. The hydraulic amplifier system of claim 3, further including an inlet check valve which supplies solvent to said secondary piston chamber.

11. A hydraulic amplifier system for supplying solvent to a chromatographic system comprising:

a first hydraulic cylinder which supplies a first pressurized solvent to said chromatographic system;

a first pump which supplies pressurized hydraulic fluid at a substantially constant rate to actuate said first hydraulic cylinder;

a second hydraulic cylinder which supplies a second pressurized solvent to said chromatographic system; and

a first pump which supplies pressurized hydraulic fluid at a substantially constant rate to actuate said second hydraulic cylinder.

12. The hydraulic amplifier system of claim 11, wherein said first hydraulic cylinder supplies said first solvent to said chromatographic system at a first constant flow rate and said second hydraulic cylinder supplies said second solvent to said chromatographic system at a second constant flow rate.

13. A hydraulic amplifier system as claimed in claim 11, wherein said first and second hydraulic cylinders comprise:

an inlet chamber;

an outlet chamber;

a primary piston disposed in said inlet chamber, said primary piston being driven by said pressurized hydraulic fluid;

a secondary piston disposed in a secondary piston chamber, said secondary piston being activated by said primary piston;

wherein a cross-sectional area of said primary piston is larger than a cross-sectional area of said secondary piston, such that a pressure in said secondary piston chamber is greater than a pressure in said inlet chamber, and a flow rate through said secondary piston chamber is less than a flow rate through said outlet chamber.

14. A hydraulic amplifier system as claimed in claim 13, wherein a ratio of said cross-sectional area of said primary piston to said cross-sectional area of said secondary piston is at least 4:

1.

15. A hydraulic amplifier system as claimed in claim 13, further including:

a first linear position transducer which measures the position of said primary piston and said secondary piston of said first hydraulic cylinder; and

a second linear position transducer which measures the position of said primary piston and said secondary piston of said secondary hydraulic cylinder.

16. A hydraulic amplifier system as claimed in claim 13, further including:

a first multiple port valve which regulates flow to said primary piston of said first hydraulic cylinder, thereby controlling said primary piston of said first hydraulic cylinder operates in one of a pump mode and a refill mode; and

a second multiple port valve which regulates flow to said primary piston of said second hydraulic cylinder, thereby controlling said primary piston of said second hydraulic cylinder operates in one of a pump mode and a refill mode

17. A hydraulic amplifier system as claimed in claim 13, further comprising:

a first pressure transducer which measures pressure in said inlet chamber of said first hydraulic cylinder;

a second pressure transducer which measures pressure in said outlet chamber of said first hydraulic cylinder, wherein measurements of said first pressure transducer and said second pressure transducer are used to compute a pressure difference across said primary piston of said first hydraulic cylinder;

a third pressure transducer which measures pressure in said inlet chamber of said second hydraulic cylinder; and

a fourth pressure transducer which measures pressure in said outlet chamber of said second hydraulic cylinder, wherein measurements of said third pressure transducer and said fourth pressure transducer are used to compute a pressure difference across said primary piston of said second hydraulic cylinder.

18. A hydraulic amplifier system as claimed in claim 13, further including a system controller for controlling said hydraulic amplifier system.

19. A hydraulic amplifier system as claimed in claim 11, further including:

a first outlet check valve attached to said first hydraulic cylinder which regulates the supply of said first solvent to said chromatographic system; and

a second outlet check valve attached to said second hydraulic cylinder which regulates the supply of said second solvent to said chromatographic system.

20. The hydraulic amplifier system of claim 13, further including:

a first inlet check valve attached to said first hydraulic cylinder which supplies said first solvent to said secondary piston chamber of said first hydraulic cylinder; and

a second inlet check valve attached to said second hydraulic cylinder supplies said second solvent to said secondary piston chamber of said second hydraulic cylinder.