Piston rod assembly for a fluid paint pump

Patent metadata

Field	Value
Publication number	US-2020088190-A1
Application number	US-201916688621-A
Country	US
Kind code	A1
Filing date	Nov 19, 2019
Priority date	Feb 21, 2017
Publication date	Mar 19, 2020
Grant date	—

Abstract

A wear sleeve is removably mounted on a piston rod. The piston rod includes a piston cap, a piston rod body, and a piston head, with at least one of the piston cap and the piston head being removable from the piston rod body. The wear sleeve is disposed over the piston rod body and prevents the piston rod from contacting dynamic seals disposed within a pump. The wear sleeve is mechanically secured in a cylindrical recess on the piston rod between a cap shoulder of the piston cap and a head shoulder of the piston head.

First claim

1 . A piston for pumping paint through a displacement pump of a paint spraying system, the piston comprising:
a piston rod body elongate along an axis between a first end and a second end; a piston head connected to the second end; a cylindrical relief extending around the piston rod body between the cap shoulder and the head shoulder; and a wear sleeve disposed about the piston rod body within the cylindrical relief; wherein the piston rod body is removably connected to the piston head by a mounting portion of the piston rod extending into a receiving portion of the piston head.

2 . The piston of claim 1 , wherein the receiving portion is a socket formed in the piston head and the mounting portion is a shank projecting from the second end.

3 . The piston of claim 2 , wherein the shank extends axially from the second end.

4 . The piston of claim 2 , wherein interfaced threading is formed on the socket and the shank, the interfaced threading securing the piston head to the piston rod body.

5 . The piston of claim 1 , wherein a check valve is disposed in the piston head.

6 . The piston of claim 1 , wherein a dynamic seal is disposed on an exterior surface of the piston head.

7 . The piston of claim 6 , wherein the dynamic seal is formed from a plurality of packing rings.

8 . The piston of claim 1 , further comprising:
a piston cap disposed at the first end, the piston cap including a radially-projecting connecting portion.

9 . The piston of claim 1 , wherein the piston head includes a first head end and a second head end, the receiving portion extending into the first head end and a central bore extending into the second head end, wherein at least one port extends through an exterior surface of the piston head and is in fluid communication with the central bore.

10 . The piston of claim 9 , wherein the piston head includes a flange extending radially from an exterior surface of the piston head.

11 . The piston of claim 10 , wherein a relief is formed on the piston head between the second head end and the flange, the relief configured to receive a dynamic seal.

12 . The piston of claim 10 , wherein at least a portion of the at least one port extends through the flange.

13 . The piston of claim 9 , wherein the piston head includes a head shoulder formed at the first head end, the head shoulder at least partially defining the cylindrical relief.

14 . A displacement pump for a paint spraying system, the displacement pump comprising:
a cylinder having an upstream end and a downstream end; a first dynamic seal mounted in the cylinder; and the piston of claim 1 , wherein the piston extends into the cylinder through the first dynamic seal; wherein the piston is configured to reciprocate within the cylinder and relative to the first dynamic seal; and wherein the wear sleeve is disposed between the first dynamic seal and the piston such that the wear sleeve is the only part of the piston contacting the first dynamic seal during reciprocation.

15 . The displacement pump of claim 8 , further comprising:
a second dynamic seal disposed on an exterior surface of the piston head, wherein the second dynamic seal is configured to reciprocate relative to the cylinder.

16 . A piston for pumping paint through a displacement pump of a paint spraying system, the piston comprising:
a piston rod body elongate along an axis between a first end and a second end; a piston head connected to the second end; and a first dynamic seal mounted on an exterior surface of the piston head; wherein the piston rod body is removably connected to the piston head by a mounting portion of the piston rod extending into a receiving portion of the piston head.

17 . The piston of claim 16 , wherein the receiving portion is a socket formed in the piston head and the mounting portion is a shank projecting from the second end.

18 . The piston of claim 17 , wherein the shank including external threads and the socket includes internal threads configured to mate with the external threads to secure the piston head to the piston rod body.

19 . The piston of claim 16 , wherein the piston head includes a first head end and a second head end, the receiving portion extending into the first head end and a central bore extending into the second head end, wherein at least one port extends through an exterior surface of the piston head and is in fluid communication with the central bore.

20 . The piston of claim 19 , wherein the piston head includes a flange extending radially from an exterior surface of the piston head, and wherein the at least one port is disposed on a first side of the flange and the first dynamic seal is disposed on a second side of the flange.

Assignees

• Graco Minnesota Inc

Inventors

• Horning Jeromy D
• Wrobel Steve J

Classifications

• F04B53/147

  Mounting or detaching of piston rod · CPC title

• F04B53/144 Primary

  Adaptation of piston-rods · CPC title

• F04B1/0408 Primary

  Pistons · CPC title

• F04B19/22

  of reciprocating-piston type · CPC title

• F04B53/14

  Pistons, piston-rods or piston-rod connections · CPC title