U.S. patent number 3,720,140 [Application Number 05/173,506] was granted by the patent office on 1973-03-13 for pump piston.
This patent grant is currently assigned to G. W. Murphy Industries, Inc.. Invention is credited to Larry E. Lee.
United States Patent |
3,720,140 |
Lee |
March 13, 1973 |
PUMP PISTON
Abstract
A single-acting pump having an elastomeric and synthetic fabric
piston seal ring and means to supply fluid to the piston to cool
and clean the piston and cylinder.
Inventors: |
Lee; Larry E. (Houston,
TX) |
Assignee: |
G. W. Murphy Industries, Inc.
(Houston, TX)
|
Family
ID: |
22632341 |
Appl.
No.: |
05/173,506 |
Filed: |
August 27, 1971 |
Current U.S.
Class: |
92/87; 92/240;
277/434 |
Current CPC
Class: |
F04B
53/143 (20130101); F04B 53/164 (20130101) |
Current International
Class: |
F04B
53/00 (20060101); F04B 53/16 (20060101); F04B
53/14 (20060101); F01b 031/00 () |
Field of
Search: |
;92/87,240,244
;277/227,233,71 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Schwadron; Martin P.
Assistant Examiner: Hershkovitz; A.
Claims
What is claimed is:
1. In a pump having a cylinder,
a single acting piston operative in said cylinder,
said single acting piston including an axially extending
cylindrical portion terminating in an enlarged radially extending
annular flange portion, said cylindrical portion having an external
diameter considerably less than the internal diameter of said
cylinder and said annular flange portion having a diameter
commensurate with the internal diameter of said cylinder,
a single elastomeric sealing ring positioned upon the cylindrical
portion of said piston in abutting engagement with said annular
flange portion.
a member carried by said cylindrical portion and engaging said
sealing ring to retain same in engagement with said flange, readily
releasable means clamping said member and sealing ring upon said
cylindrical portion of said piston,
said sealing ring having a sliding engagement with the inner
surface of said cylinder,
said annular flange portion having a circumferential fluid
passageway provided in the peripheral surface thereof,
said annular flange portion having fluid passageways communicating
with said circumferential fluid passageway to conduct a fluid to
the inner surface of said cylinder proximate said sealing ring and
flange portion to form a continuous film of fluid behind said
piston for cooling and cleaning the cylinder and sealing ring.
Description
SUMMARY
This invention relates to pump pistons for use in mud or slush
pumps used in connection with petroleum well drilling apparatus,
pipeline, mining and related industries, and particularly to a
piston having an elastomeric seal ring including synthetic material
fabric and fluid means for washing, cooling and lubricating the
piston and the wall of the cylinder or liner in which it
operates.
In double-acting pumps, the piston is flooded on both sides, as is
the liner, with the fluid being pumped, whereas, in a single-acting
pump, only the working face of the piston is so flooded so that on
the back stroke of the piston abrasive substances may be on the
liner, and the wall thereof may be relatively dry, which can result
in abrasive wear on the piston, seal ring and liner wall, and which
may result in excessive heating of these parts particularly in
modern high speed pumps.
It is an object of this invention to provide a new and improved
piston for a single-acting pump, which piston employs an
elastomeric seal ring having synthetic material fabric which has a
relatively low operating temperature limit but which gives superior
results over other piston seals when supplied with the new and
improved fluid circulating system of the invention.
My invention has other objects and advantages some of which, with
the foregoing, will be set forth in the description which
follows.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is fragmentary sectional view of a single-acting pump
showing the piston in operating position in a liner.
FIG. 2 is an enlarged view, partly in axial section, of the pump
and piston shown in FIG. 1.
FIG. 3 is an enlarged view, partly in axial section, showing
another embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIGS. 1 and 2, a pump piston cylinder assembly is
shown comprising a single-acting piston 10 carried by a piston rod
11 and adapted for reciprocation within a cylinder or liner 12. The
piston 10 includes a piston head 13 having an axially extending
cylindrical portion 14 and a radially extending annular flange 15.
The piston rod 11 has a reduced threaded end 16 and an annular
flange 17. The piston head 13 is mounted on the threaded end 16 and
a nut 18 secures the piston head 13 against the annular flange
17.
A seal ring 20 is placed on the cylindrical portion 14 against the
flange 15, and an annular spacer 21, which is contoured to fit the
working face of the seal ring 20, is placed against the ring 20.
The seal 20 and spacer 21 are secured on the piston head 13 by
means of a split retaining ring 22 or other suitable means. The
piston rod 11 may have wrench flats 23 thereon to hold the rod with
a wrench while the nut 18 is being applied to or removed from the
rod. The rod 11 has a flange 24 which is adapted to be connected to
a power source which is shown generally at 25. The piston head 13
has a groove 26 into which is disposed a seal ring 27 to effect
sealing between the end 16, the head 13 and the flange 17.
The seal ring 20 may comprise generally an elastomeric material
such as Buna-N or, other suitable material, having molded therein a
fabric 26 which may comprise a regular weave or square woven nylon
fabric or other suitable synthetic material.
The periphery of flange 15 when new has a small diametral clearance
with the wall of the liner 12 of preferably about two and one-half
thousandths to about seven and one-half thousandths of an inch. The
flange 15 has an annular groove 28 in its periphery. A radially
extending hole 29 is drilled inwardly from the bottom of the groove
28. Another hole 30 is provided in flange 15 to intersect hole 29
and thereby establish communication with the annular groove 28. A
tube 31 is secured in the hole 30. Seal means 31a is provided
between the wall of the hole 30 and the tube 31. The tube 31 may be
secured to the piston rod 11 by means of clamps 32. A flexible
conduit 33 is connected at one end to the tube 31 and connected at
its other end to a pressure source of fluid, which may be water or
other suitable fluid. As can be seen in FIG. 1, the flexible
conduit permits the piston to be moved from its rearward position,
as shown, to a forward position, moving a distance indicated at
34.
Another embodiment of the invention is shown in FIG. 3, which is
similar to that shown in FIGS. 1 and 2, except that fluid supply in
this embodiment is carried through flexible conduit 40 which is
threadedly secured into piston rod 41, communicating with
passageways 42 and 43. The flange 44 of piston head 45 has
passageways 46 communicating with passageway 43 and an annular
groove 47 in the periphery of flange 44.
In operation, fluid in sufficient volume under ample pressure is
forced between the piston flange and cylinder to form a continuous
film of fluid behind the piston. This fluid film cools, cleans and
lubricates the seal ring and cylinder and helps to prevent air and
foreign material from being drawn into the working chamber by the
piston on its back stroke.
The fluid forced through the small clearance between the piston
flange and cylinder is more efficient, more uniformly distributed,
and less fluid is required than an open spray system which directs
a stream of liquid onto the back side of the piston.
The fabric 26, which is preferably nylon or the like molded into
the seal ring 20, is much superior to the cotton fabrics previously
used in such pump piston seals because it has higher tensile
strength, a lower coefficient of friction and a good ability to
stretch before breaking. Such a seal will have greatly increased
field performance if it can be kept sufficiently cool in operation.
Nylon or the like is much more heat sensitive than cotton fabric,
but its other properties, as above mentioned, make such a
nylon-reinforced seal very desirable especially for use in modern
high speed pumps. With the cooling arrangement of my invention,
such seal has been proven to be superior in actual field use.
While the embodiments of the invention as herein disclosed
constitute preferred forms, it is to be understood that other forms
may be adopted within the scope of the appended claims.
* * * * *