Reciprocating pump valve assembly with thermal relief

Patent metadata

Field	Value
Publication number	US-9611844-B2
Application number	US-201214112683-A
Country	US
Kind code	B2
Filing date	Apr 25, 2012
Priority date	Apr 27, 2011
Publication date	Apr 4, 2017
Grant date	Apr 4, 2017

Abstract

A reciprocating pump comprises a cylinder, an inlet check valve, a piston, an outlet check valve and a purge circuit. The cylinder has a first end and a second end. The inlet check valve is disposed proximate a first end of the cylinder. The piston is disposed within the cylinder between the inlet check valve and the second end. The outlet check valve is disposed within the piston. The purge circuit extends across the inlet check valve and the outlet check valve to fluidly couple the first end and the second end.

First claim

The invention claimed is:

1. A piston pump comprising:
a cylinder comprising an inlet and an outlet;
a piston disposed within the cylinder between the inlet and the outlet and actuated by a motor to drive a fluid in a primary flow direction from the inlet to the outlet of the cylinder, wherein the piston has an outer surface that engages an inner surface of the cylinder to define a first chamber between the piston and the inlet of the cylinder and a second chamber between the piston and the outlet of the cylinder;
a first check valve disposed between the piston and the inlet and configured to permit flow of the fluid in the primary flow direction from the inlet to the first chamber and to prevent flow of the fluid from the first chamber to the inlet;
a second check valve disposed within the piston and configured to permit flow in the primary flow direction from the first chamber to the second chamber when the piston is actuated towards the inlet and to prevent flow from the second chamber into the first chamber when the piston is actuated towards the outlet;
a first bypass passage extending through the first check valve; and
a second bypass passage extending from the first check valve along the cylinder;
wherein the first and second bypass passages form a return path fluidically connecting the outlet to the inlet of the cylinder such that fluid is permitted to flow in a direction opposite the primary flow direction during each stroke of the piston when the piston engages the second bypass passage.

2. The piston pump of claim 1 wherein the first check valve comprises:
a ball seat disposed proximate the inlet;
a ball disposed within the ball seat; and
a spring biasing the ball into the ball seat;
wherein the first bypass passage extends through the ball seat.

3. The piston pump of claim 2 wherein the first bypass passage comprises a hole extending internally through the ball seat away from a mate face with the ball.

4. The piston pump of claim 1 wherein the piston comprises:
a disk-shaped head comprising:
a diameter to mate with that of the cylinder; and
a height;

a seal extending around the head to engage the cylinder.

5. The piston pump of claim 4 wherein the second bypass passage is longer than the height of the disk-shaped head.

6. The piston pump of claim 4 and further comprising a plurality of second bypass passages.

7. The piston pump of claim 4 wherein the second bypass passage comprises a groove extending along an inner surface of the cylinder.

8. The piston pump of claim 1 wherein the motor is an air motor having a rod coupled to the piston within the cylinder.

9. A reciprocating pump comprising:
a cylinder having a first end and a second end;
a piston disposed within the cylinder between the first end and the second end of the cylinder;
an inlet check valve disposed proximate the first end of the cylinder and configured to permit unidirectional flow from the first end of the cylinder to a first chamber between the piston and the inlet check valve;
an outlet check valve disposed within the piston and configured to permit unidirectional flow from the first chamber to a second chamber between the piston and the second end of the cylinder; and
a purge circuit extending across the inlet check valve and the outlet check valve to fluidly couple the first end and the second end of the cylinder and to permit flow in a direction opposite the unidirectional flow permitted by the inlet and outlet check valves, wherein the purge circuit comprises:
a first bypass passage extending through the inlet check valve; and
a second bypass passage extending around the piston and the outlet check valve, wherein the piston engages the second bypass passage with each stroke of the piston.

10. The reciprocating pump of claim 9 wherein:
the inlet check valve comprises:
a first ball seat disposed in a valve housing coupled to the cylinder;
a first ball; and
a first spring to bias the first ball toward the first ball seat and away from the piston; and

the outlet check valve comprises:
a second ball seat disposed in the piston;
a second ball; and
a second spring to bias the second ball toward the second ball seat and toward the inlet check valve.

11. The reciprocating pump of claim 10 wherein:
the first bypass passage comprises a bore through the first ball seat for the inlet check valve; and
the second bypass passage comprises a channel on an interior of the cylinder to extend across the piston and the outlet check valve.

12. The reciprocating pump of claim 9 and further comprising:
a suction tube coupled to the first end of the cylinder.

13. The reciprocating pump of claim 12 and further comprising:
a priming check valve disposed in the suction tube.

14. A method of providing thermal relief in a reciprocating piston pump, the method comprising:
pumping a fluid from a container upstream of a pump to a dispenser downstream of the pump by reciprocating a piston in a cylinder between a first end and a second end thereof, wherein displacing the piston towards the second end of the cylinder draws fluid through an inlet check valve proximate the first end, the inlet check valve permitting unidirectional flow from the first end to a first chamber between the piston and the inlet check valve, and wherein displacing the piston towards the first end of the cylinder pumps the fluid through an outlet check valve within the piston, the outlet check valve permitting unidirectional flow from the first chamber to a second chamber between the piston and the second end of the cylinder; and
relieving fluid pressure between the dispenser and the pump generated by thermal expansion of the fluid by passing thermally expanded fluid through a purge circuit fluidly coupling the first end and the second end to permit flow in a direction opposite the unidirectional flow permitted by the inlet and outlet check valves, wherein the purge circuit extends across the inlet check valve and the outlet check valve to connect the dispenser to the container when the piston is not reciprocating, and wherein the purge circuit comprises:
a first passage extending through the inlet check valve between the pump and the container; and
a second passage bypassing the piston within the cylinder, wherein the piston engages the second passage with each stroke of the piston.

15. The method of claim 14 wherein:
the first passage comprises a bore formed in a valve seat for the inlet check valve; and
the second passage comprises a channel formed on an interior of the cylinder from the first end to a height greater than that of the piston.

16. The method of claim 14 and further comprising:
balancing pressure in the cylinder on opposite sides of the piston using the purge circuit when the piston is not reciprocating.

Assignees

• Bauck Mark L
• You Zaixing
• Wu Xueshui
• Grandahl Jr Clinton Craig
• Graco Minnesota Inc

Inventors

• Bauck Mark L
• You Zaixing
• Wu Xueshui
• Grandahl Jr Clinton Craig

Classifications

• F04B53/12 Primary

  arranged in or on pistons · CPC title

• F16N11/10

  by pressure of another fluid · CPC title

• F04B49/035 Primary

  Bypassing · CPC title

• F04B53/126

  Ball valves · CPC title

• F16K15/04 Primary

  shaped as balls · CPC title