Note: Descriptions are shown in the official language in which they were submitted.
CA 02486229 2009-10-21
COOLANT SYSTEM FOR PISTON
AND LINER OF RECIPROCATING PUMPS
BACKGROUND OF THE INVENTION
1. Field of the Invention
[00021 The present invention relates generally to reciprocating pumps, more
specifically to a coolant system for the piston and liner of the reciprocating
pumps.
2. Background of the Invention
100031 In oil field operations, reciprocating pumps are often used for various
purposes. Some reciprocating pumps, generally known as "mud pumps," are
typically
used for well drilling operations. During operation, the pistons and liners of
the
pumps generate large amounts of heat due to friction. It is desirous to cool
the liners
and pistons in order to extend their operation lives, which in turn increases
overall
efficiency and reduces down-time for maintenance.
[00041 Prior systems for cooling pistons and liners includes various coolant
injector
systems. For example, in one system, a coolant line or hose is physically
coupled to
the piston rod with a the hose feeding into the piston. The coolant hose moves
with
the piston rod during operations. The hose in this system typically has a
short life due
to wear associated with moving with the piston rod. Another system includes a
hose
that connects to an outer surface of the piston rod that transmits the coolant
through
the piston rod to a sprayer located in the piston rod adjacent the piston. The
hose in
this assembly also has problems with wear because the hose connects to and
reciprocates with the piston rod.
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CA 02486229 2009-10-21
SUMMARY OF THE INVENTION
[0005] In this invention, a reciprocating pump assembly includes piston rod
that is
movable and reciprocates in order to pump a fluid. The piston rod has a piston
portion at an end that stokes within a piston chamber. The pump assembly also
includes a piston rod sleeve that houses the piston rod. The piston rod sleeve
does not
reciprocate with the piston rod, so the piston rod sleeve remains stationary.
The piston
rod sleeve also defines and annulus between the piston rod and the piston rod
sleeve.
The pump assembly has a fluid line that leads into the annulus. The fluid line
delivers
coolant to the annulus. The pump assembly also includes a flow passage. The
flow
passage has an inlet in fluid communication with the annulus for receiving the
coolant. The passage also has an outlet in fluid communication with the piston
chamber for delivering the coolant.
[0006] The flow passage of the pump assembly may be located within the piston
rod.
As such, the coolant flows through an interior of the piston rod between the
inlet and
outlet of the flow passage. The pump assembly can also include a fluid
sprayer. The
sprayer is typically located at the outlet of the flow passage in order to
deliver a spray
of fluid into the piston chamber.
[0007] The piston rod can include an outer shell that has an inner
circumference. The
piston rod can also include a pony rod that is located within the outer shell
and has an
outer circumference that is less than inner circumference of the outer shell.
The pony
rod and the outer shell define a clearance between the inner surface of the
outer shell
and the outer surface of the pony rod. The clearance can be a portion of the
flow
passage for carrying the coolant from the annulus and the piston chamber.
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CA 02486229 2009-10-21
[0007A] By way of example, the invention comprehends a reciprocating pump
assembly, comprising a housing having a piston chamber with a working fluid
inlet
and a working fluid outlet, a crankshaft rotatably driven in the housing, and
a
connector rod having a first end mounted to the crankshaft for rotation
therewith and
a second end. A movable piston rod is pivotally mounted to the second end of
the
connector rod, the piston rod having a piston portion at an end that stokes
linearly
within the piston chamber, and the piston portion having a working fluid side
for
pumping out the outlet working fluid entering the inlet. A stationary piston
rod
sleeve houses the piston rod and defines an annulus, and a cooling fluid line
leads into
the annulus. A cooling fluid flow passage has an inlet in fluid communication
with
the annulus and an outlet in fluid communication with the piston chamber on a
side
of the piston portion opposite the working fluid side for cooling the piston
portion.
[0007B] Another aspect of the invention comprehends a reciprocating pump
assembly, comprising a movable piston rod having a piston at an end that
strokes
within a piston chamber, the piston rod having an outer shell with a tubular
cross
section and a pony rod extending therethrough, the outer shell and the pony
rod
defining a clearance between the outer surface of the pony rod and the inner
surface
of the outer shell. The piston rod also has a tubular extension attached to
the outer
shell and the pony rod, the tubular extension defining an extension annulus. A
stationary piston rod sleeve houses each of the piston rod and the pony rod
and
defines a sleeve annulus, and a fluid line leads into the sleeve annulus. The
flow
passage comprises the clearance between the pony rod and outer shell and the
extension annulus, the flow passage having an inlet located in the clearance
that is in
fluid communication with the sleeve annulus and an outlet located in the
tubular
extension that is in fluid communication with the piston chamber.
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CA 02486229 2009-10-21
[0007C] Still further, the invention pertains to a method of cooling a portion
of
a reciprocating pump, comprising providing a movable piston rod with a piston
portion, the piston rod having a flow passage extending therethrough with an
outlet
in fluid communication with a piston chamber, housing the piston rod within a
piston
rod sleeve that defines an annulus, connecting a fluid line to the piston rod
sleeve so
the fluid line is in fluid communication with the annulus, reciprocating the
piston rod
within the piston rod sleeve, and transmitting a coolant from the fluid line
to the
outlet of the flow passage.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] Figure 1 is a schematic elevational view of a reciprocating pump
assembly constructed in accordance with this invention.
[0009] Figure 2 is a top plan schematic view of the reciprocating pump
assembly shown in Figure 1.
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[0010] Figure 3 is a sectional view of a portion of the pump assembly shown in
Figure 1.
[0011] Figure 4 is an enlarged sectional view of a portion of the pump
assembly
shown in Figure 1.
[0012] Figure 5 is an enlarged portion of the portion of the pump assembly
shown in
Figure 4.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0013] Referring to Figure 1, a reciprocating pump 11 includes a crankshaft
housing
13 that comprises a majority of the outer surface of reciprocating pump 11
shown in
Figure 1. A piston rod housing 15 attaches to a side of crankshaft housing 13
and
extends to a piston chamber or cylinder 17. Cylinder 17 preferably includes a
fluid
inlet 19 and a fluid outlet 21 (Figure 2).
[0014] Referring to Figure 2, piston rod housing 15 is segmented into three
portions,
each portion comprising a piston throw 23. Reciprocating pump 11 as shown in
Figure 2 has three piston throws 23, which is commonly know as a triplex, but
could
also be segmented for five piston throws 23, which is commonly known as a
quintuplex pump. The description focuses on a triplex pump, but as will be
readily
apparent to those skilled in the art, the features and aspects described are
easily
applicable for pumps with various numbers of piston throws 23. Each piston
throw
23 houses a piston rod 33 (Figure 3) extending toward cylinder 17. As shown in
Figure 2, each piston throw 23 extends in the same longitudinal direction from
crankshaft housing 13.
[0015] Referring to Figure 3, a portion of reciprocating pump 11 housed within
crankshaft housing 13 is shown. Crankshaft housing 13 houses a crankshaft 25,
which is typically connected to a motor (not shown). The motor (not shown)
rotates
crankshaft 25 in order to drive reciprocating pump 11. In the
preferred.embodiment,
crankshaft 25 is cammed so that fluid is pumped from each piston throw 23 at
alternating times. As is readily appreciable by those skilled in the art,
alternating the
cycles of pumping fluid from each of cylinders 17 helps minimize the primary,
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secondary, and tertiary (et al.) forces associated with reciprocating pump 11.
In the
preferred embodiment, a connector rod 27 includes an end that connects to
crankshaft
25 and another end that engages a crosshead 29. Connector rod 27 connects to
crosshead 29 through a crosshead pin 31, which holds connector rod 27
longitudinally
relative to crosshead 29. Connector rod 27 pivots about crosshead pin 31 as
crankshaft 25 rotates with the other end of connector rod 27. A piston rod 33
extends
from crosshead 29 in a longitudinally opposite direction from crankshaft 25.
Connector rod 27 and crosshead 29 convert rotational movement of crankshaft 25
into
longitudinal movement of piston rod 33. A crosshead housing 32, located in
crankshaft housing 13, extends longitudinally away from crankshaft 25. In the
preferred embodiment, crosshead housing 32 guides crosshead 29 as crosshead 29
reciprocates longitudinally relative to crankshaft 25.
[0016] Referring to Figure 4, a piston portion 35 connects to piston rod 33
for
pumping the fluid passing through reciprocating pump 11. As illustrated in
Figure 4,
piston portion 35 is a piston. Cylinder 17 (Figure 1) connects to the end of
piston rod
housing 15 extending away from crankshaft housing 13 (Figure 1). Cylinder 17
typically includes a cylinder chamber, which is where the fluid being pumped
by
reciprocating pump 11 is pressurized by piston 35. Piston rod 33 preferably
includes
an outer shell or outer casing 37 and a pony rod 39, that are each connected
to and
extending away from crosshead 29. Pony rod 39 is preferably a solid shaft
having a
threaded profile toward the end extending away from crosshead 29. Outer casing
37
preferably encloses a substantial portion of pony rod 39, thereby defining a
rod
annulus 40 in the area between pony rod 39 and outer casing 37.
[0017] Piston rod 33 also preferably includes a tubular extension or extension
rod 41
connected to the ends of pony rod 39 and outer casing 37. Extension rod 41
extends
longitudinally away from crankshaft 25 (Figure 3) to connect piston rod 33
with
piston 35. Piston rod 33 also preferably includes a rod clamp assembly 43 that
connects extension rod 41 with the ends of outer casing 37 and pony rod 39. In
the
preferred embodiment, rod clamp assembly 43 includes an intermediate casing 45
that
abuts an end portion of outer casing 37 and receives a portion of pony rod 39.
A
portion of intermediate casing 45 is flared so that the outer diameter of
intermediate
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CA 02486229 2004-10-28
casing 45 located toward the end extending away from crankshaft 25 is greater
than
other portions of intermediate casing 45. Extension rod 41 also has a flared
portion
located toward the end of extension rod 41 that is being connected to pony rod
39 and
outer casing 37.
[0018] The flared portions of intermediate casing 45 and extension rod 41 abut
and
are held relative to each other by an outer clamp 47. Outer clamp 47 encloses
the
interface of intermediate casing 45 and extension rod 41. Outer clamp 47 has a
recess
portion which surrounds the flared portions of extension rod 41 and
intermediate
casing 45. Therefore, as outer casing 37 reciprocates longitudinally toward
and away
from crankshaft 25, extension rod 41 must also reciprocate toward and away
crankshaft 25.
[0019] In the preferred embodiment, extension rod 41 is a tubular member which
also
receives and encloses a portion of pony rod 39. Preferably an inner sleeve 49,
having
a threaded profile that matingly engages with the threaded profile located
toward the
end of pony rod 39 extending away from crankshaft 2:5, is positioned at the
interface
of intermediate casing 45 and extension rod 41. Intermediate casing 45
preferably
includes an inner bore which receives a portion of inner sleeve 49 and
prevents inner
sleeve 49 from moving relative to intermediate casing 45 closer to crankshaft
25.
Extension rod 41 also preferably has an inner bore which receives a portion of
inner
sleeve 49, which prevents inner sleeve 49 from moving relative to extension
rod 41.
In the preferred embodiment, an extension rod annulus 50 is defined between
piston
35, inner sleeve 49, the end of pony rod 39 extending away from crankshaft 25,
and
the interior of extension rod 41. Piston 35 connects to the end of extension
rod 41
extending away from rod clamp assembly 45. In the preferred embodiment, a
plurality of passages 51 extend longitudally through inner sleeve 49, between
rod
annulus 40 and extension rod annulus 50, around the threaded portion of pony
rod 39
so that rod annulus 40 and extension annulus 50 are in fluid communication
through
rod clamp assembly 43.
[0020] A piston liner 55 adjoins to an interior surface of cylinder 17. In the
preferred
embodiment, piston liner 55 is in fluid communication with an interior portion
of
CA 02486229 2004-10-28
cylinder 17 and thereby defining a pumping chamber of reciprocating pump
assembly
11. Piston 35 slidingly engages piston liner 55 as piston 35 reciprocates
longitudinally toward and away from crankshaft 25. Reciprocating piston 35
within
piston liner 55 causes the volume of the pumping chamber to increase and
decrease as
piston 35 reciprocates longitudinally toward and away from crankshaft 25,
thereby
positively displacing the fluid being pumped through reciprocating pump 11.
[00211 Piston 35 typically experiences wear from the heat created by sliding
engagement of piston liner 55 during normal pumping operations. Typically the
fluid
being pumped through the pumping chamber of reciprocating pump 11 helps to
lubricate and cool the portion of piston liner 55 on the cylinder side of
piston 35. A
coolant assembly 57 provides coolant to the crankshaft 25 side of piston 35 to
prevent
excessive heat and wear between piston 35 and piston liner 55. In the
preferred
embodiment, coolant assembly 57 preferably includes a piston rod sleeve or
coolant
sleeve 59 extending between crosshead housing 32 and the portion of crankshaft
housing 13 that engages piston rod housing 15. Coolant sleeve 59 preferably
encloses
outing casing 37 of piston rod 33 and is stationary. Seats 61 preferably seal
the end of
coolant sleeve 59 adjacent crosshead housing 32 and the end of connector
sleeve 59
adjacent rod clamp assembly 43. The interior surface of coolant sleeve 59 and
seals
61 thereby define a sleeve annulus 63 surrounding outer casing 37 of piston
rod 33.
In the preferred embodiment, a fluid line or injector hose 65 injects a
coolant into
sleeve annulus 63 through a sleeve port 67 extending through a side of sleeve
59.
Injector hose 65 typically extends away from lubricator sleeve 59 to an outer
surface
of crankshaft housing 13 to receive the coolant from a coolant source (not
shown).
[00221 In the preferred embodiment, seal 61 located adjacent crosshead housing
32 is
placed a predetermined distance from seal 61 located adjacent the end of
crankshaft
housing 13 extending away from crankshaft 25, such that the distance between
seals
61 is greater than or substantially equal to the length of the stroke of
piston 35. In the
preferred embodiment, an outer shell or casing port 69 extends through a side
of outer
casing 37 of piston rod 33. Rod annulus 40 and sleeve annulus 63 are in full
communication through outer casing port 69. Rod annulus 40 and sleeve annulus
63
are in fluid communication throughout the entire stroke length of the piston
rod. In
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the preferred embodiment, outer casing port 69 is formed on a portion of outer
casing
37 such that outer casing port 69 is always substantially between seals 61
during
operations of reciprocating pump 11. Therefore, coolant from injector hose 65
that
accumulates in sleeve annulus 63 can readily communicate through outer casing
port
69 into rod annulus 40 while piston rod 33 reciprocates toward and away from
crankshaft 25. In the preferred embodiment, the coolant that communicates from
sleeve annulus 63 through outer casing port 69 travels along pony rod 33
toward
passages 51 and inner sleeve 49. The coolant communicates through passages 51
from rod annulus 40 and into extension annulus 50 toward piston 35.
[0023] Referring to Figures 4 and 5, a spray port 71 is formed in extension
rod 41 at a
position adjacent piston 35. An injector sprayer 73 is preferable located
within a
spray port 71. Spray port 71 and injector sprayer 73 are preferably angled so
that
coolant is sprayed along the crankshaft 25 (Figure 3) side of piston 35 and
piston liner
55. Therefore, in the preferred embodiment the coolant flows from sleeve
annulus 63
through a continues passage that includes outer casing port 69, rod annulus
40,
passages 51 within clamp assembly 43, extension annulus 50 and spray port 71.
This
flow passage is merely a preferred embodiment, and as will be readily
appreciated by
those skilled in the art, this passageway is subject change due to slight
variations.
[0024] Coolant assembly 57 advantageously provides coolant to the crankshaft
25
side of piston 35 and piston liner 55. This reduces excessive heat and wear
between
piston 35 and piston liner 55. Coolant assembly 57 also advantageously
provides and
assembly in which fluid line or fluid hose 65 remains stationary during pump
operations. Therefore, hose 65 is not subject to the reciprocating movements
that
cause wear and failure in previous cooling assemblies. Accordingly, pumping
operations can continue for longer periods of time between replacement of the
fluid
hose 65.
[0025] While the invention has been shown in only one of its forms, it should
be
apparent to those skilled in the art that it is not so limited, but is
susceptible to various
changes without departing from the scope of the invention. For example,
injector
hose 65 can extend from lubricator sleeve 59 toward a side portion of
crankshaft
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housing 13 as shown in Figure 4 or toward a lower portion of crankshaft
housing 13
as shown in Figure 3 to receive coolant fluid from a coolant source (not
shown). A
further example that can be readily appreciated by those still in the art,
while the
invention has only been shown with respect to mud pumps, the same lubrication
system can also be easily adapted for service pumps using a piston attached to
a pony
rod.
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