Note: Descriptions are shown in the official language in which they were submitted.
CA 02486223 2009-10-23
MANIFOLD ASSEMBLY FOR RECIPROCATING PUMP
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0002] The present invention relates generally to reciprocating pumps, and
more
specifically to a manifold assembly of an oil field mud or service pump.
2. Background of the Invention
[0003] In oil field operations, reciprocating pumps are often used for various
purposes. Some reciprocating pumps are generally known as "service pumps" that
are
typically used for operations such cementing, acidizing, or fracing the well.
Typically, these service pumps run for short periods of time, but on a
frequent basis.
Other reciprocating pumps, generally known as "mud pumps," are typically used
for
circulating drilling mud downhole through a drill string and back up to the
surface
along the outer surface of the drill string during drilling operations.
Typically, these
mud pumps run for long continuous periods of time.
[0004] A typical reciprocating pump has a fluid end block with an inlet and an
outlet
for fluid to enter and exit the pumping chambers. The piston chambers are
horizontal.
The inlet is typically located below the piston chambers, and is fed fluid
from an inlet
manifold attached below the piston chamber. Inlet valve assemblies generally
extend
vertically upward from a lower surface of the fluid end block, and into the
piston
chambers, to selectively open the inlets of the piston chambers.
[00051 Outlet valve assemblies also typically extend vertically down from the
upper
surface of the fluid end block to selectively open the outlet of the piston
chamber.
Each outlet vavve assembly is generally coaxial with an inlet valve assembly.
The
outlet discharges the fluid to a discharge manifold. The vertical dimension of
the
fluid end is fairly large because the inlet valve assembly is located directly
below the
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outlet assembly. In some installations, the amount of space for the fluid end
is
limited.
SUMMARY OF THE INVENTION
[0006] In this invention, a cylinder or fluid end block assembly fora
reciprocating
pump includes a block body. The block body defines a piston chamber adapted to
receive a piston of the reciprocating pump. The cylinder block assembly has an
outlet
valve assembly positioned within the block body. The outlet valve assembly is
positioned such that it is in fluid communication with the piston chamber. An
outlet
valve retainer retains the outlet valve relative to the piston chamber. The
cylinder
block assembly also includes an inlet valve assembly. The inlet valve assembly
extends through a side of the block body to the piston chamber. An inlet valve
retainer also retains the inlet valve assembly relative to the piston chamber.
The
cylinder block assembly also includes a discharge passage extending from the
outlet
valve assembly to another side of the block body. A portion of the discharge
passage
extends between the inlet valve assembly and the inlet valve retainer.
[0007] The cylinder block assembly can have an inlet valve assembly that
includes a
first flange and a second flange connected by a column. In this inlet valve
assembly
the column extends through the discharge passage. The first flange in such an
assembly defines a first cross-sectional area while the second flange defines
a second
cross-sectional area. The first cross-sectional area is larger than the second
cross-
sectional area. The column defines a third cross-sectional area that is
smaller than
both the first and second cross-sectional areas defined by the first and
second flanges.
[0008] The invention can also optionally include an inlet valve assembly
having a
spring-loaded valve extending from the second flange. The spring-loaded valve
extends from the second flange through the piston chamber to an inlet of the
piston
chamber to selectively open and close the inlet of the piston chamber. The
spring-
loaded valve can include a valve member and a spring member. The spring member
biases the valve member toward a closed position to sealingly engage the inlet
of the
piston chamber. The spring member actuates the valve member to an open
position
when the pressure differential across the valve member is larger than a
predetermined
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amount. The first and second flanges, and the column remain stationary
relative to the piston
chamber so that the valve member moves relative to the second flange.
[0008A] More particularly, the invention in one broad aspect provides a
cylinder block
assembly for a reciprocating pump, comprising a block body defining a piston
chamber
adapted to receive a piston of a reciprocating pump, an outlet valve assembly
positioned
within the block body and having an outlet valve actuation axis in fluid
communication with
the piston chamber, and an outlet valve retainer that retains the outlet valve
relative to the
piston chamber. An inlet valve assembly is positioned within the block body
and has an inlet
valve actuation axis in fluid communication with the piston chamber, the inlet
valve actuation
axis being parallel to and non-coaxial with the outlet valve actuation axis.
An inlet valve
retainer retains the inlet valve assembly relative to the piston chamber, and
a discharge
passage extends from the outlet valve assembly to a side of the block body, a
portion of the
discharge passage extending between the inlet valve assembly and the inlet
valve retainer.
[0008B] The invention also pertains in another aspect to a reciprocating pump
assembly having a pump housing that houses a crankshaft, a plurality of
pistons mechanically
connected to the crankshaft for pumping a fluid through a cylinder block, the
cylinder block
defining a cylindrical piston chamber for each of the pistons that receives
fluid from an inlet
manifold and a fluid outlet that conveys fluid to an outlet manifold. The
reciprocating pump,
comprises a plurality of outlet valves associated with and being in fluid
communication with
each respective piston chamber defined by the cylinder block, which outlet
valves actuate
along a respective outlet valve axis to an open position when an outlet valve
fluid pressure
differential exceeds a predetermined outlet valve differential across
respective ones of the
outlet valves. A plurality of inlet valves extend through a side of the
cylinder block portion
to each of respective ones of the piston chambers, which inlet valves actuate
along a
respective inlet valve axis to an open position when an inlet valve fluid
pressure differential
exceeds a predetermined inlet valve differential across respective ones of the
inlet valves, the
inlet valve axes being parallel to and offset from respective ones of the
outlet valve axes. A
plurality of discharge passages extends from respective ones of the outlet
valves to the outlet
manifold. An inlet valve retainer is provided for each of the inlet valves
that retains
respective ones of the inlet valves relative to respective ones of the piston
chambers, each of
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the inlet valve retainers extending along respective ones of the inlet valve
axes and through
respective ones of the discharge passages.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Figure 1 is a schematic elevational view of a reciprocating pump
assembly
constructed in accordance with this invention.
[0010] Figure 2 is a top plan schematic view of the reciprocating pump
assembly
shown in Figure 1.
[0011] Figure 3 is a sectional view of a portion of the pump assembly shown in
Figure
1.
[0012] Figure 4 is a sectional view of another portion of the pump assembly
shown
in Figure 1.
[0013] Figure 5 is a partial sectional view of the fluid inlet portion of one
of the
cylinders in the pump assembly shown in Figure 4.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0014] 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 motor 12, located adjacent crankshaft housing 13, drives reciprocating
pump 11. Motor
12 optionally transfers rotational movement to pump 11 through belts, chains,
gears, or a
direct coupling. A plunger or piston rod housing 15 attaches to a side of
crankshaft housing
13 and extends to a cylinder or fluid end block 17. Fluid end block 17
preferably includes
a plurality of cylinders, each with a fluid inlet portion 19 and a fluid
outlet portion 21.
[0015] Referring to Figure 2, piston rod housing 15 has several portions, each
portion
comprising a plunger or piston throw 23. Reciprocating pump 11 as shown in
Figure 2 has
three piston throws 23, which is commonly known 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
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those skilled in the art, the features and aspects described are easily
applicable for a
quintuplex pump. Each piston throw 23 houses a pony rod 33 (Figure 3), which
connects to a piston 35 (Figure 4) extending to fluid end 17. As shown in
Figure 2,
each piston throw 23 extends in the same longitudinal direction from
crankshaft
housing 13.
(0016] Referring to Figure 3, a portion of reciprocating pump 11 housed within
crankshaft housing 13 is shown. Crankshaft housing; 13 encloses a crankshaft
25,
which is typically connected to motor 12 (Figure 1). Motor 12 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 of fluid end 17 helps minimize the primary,
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. Pony 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 pony rod 33.
[0017] Referring to Figure 4, piston 35 connects to pony rod 33 for pumping
the fluid
passing through reciprocating pump 11. Fluid end 17 connects to the end of
piston
rod housing 15 that is opposite from crankshaft housing 13 (Figure 1).
Cylinder 17
typically includes a cylinder chamber 37, which is where the fluid being
pumped by
reciprocating pump 11 is pressurized by piston 35. Cylinder 17 preferably
includes an
inlet valve 39 and an outlet valve 41, with outlet valve 41 located rearward
of inlet
valve 39. Valves 39, 41 are preferably spring-loaded valves, which are
actuated by a
predetermined differential pressure. Inlet valve 39 actuates to control fluid
flow
through fluid inlet portion 19 into cylinder chamber 37, and outlet valve 41
actuates to
control fluid flow through fluid outlet portion 21 from cylinder chamber 37.
Inlet and
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outlet valves 39, 41 reciprocate on axes that are parallel to each other. An
outlet valve
retainer or threaded nut 42 engages a threaded bore formed in cylinder and
holds
outlet valve 41 in position relative to cylinder chamber 37. A discharge
passage 43
extends through a side of fluid outlet portion 21 and through fluid inlet
portion 19 to
discharge manifold 22. In the preferred embodiment, discharge passage 43 is
located
above cylinder chamber 37 and extends in a substantially longitudinal
direction from
outlet valve 41 to discharge manifold 22.
[0018] In the preferred embodiment, inlet valve 39 is preferably an assembly
that
includes a suction or inlet valve cover or retainer 45 that is located
substantially above
cylinder chamber 37. Suction valve cover 45 is a spool-shaped member with a
first
flange or upper portion 47 and a second flange or lower portion 49 and a stem
or
column 51 extending therebetween. In the preferred embodiment, lower portion
49
has a height that is substantially the same as the portion of fluid inlet
portion 19
located between discharge passage 43 and cylinder chamber 37. Column 51,
extending above lower portion 49, preferably has a height that is
substantially equal to
the height of discharge passage 43 so that the lower edge of upper portion 47
is
substantially flush with the upper edge of discharge passage 43. Column 51
preferably extends to a height that provides the portion of discharge passage
43
extending through inlet valve cover 45 with a cross-sectional area that is
equal to or
greater than the cross-sectional area of the other portions of discharge
passage 43. In
the preferred embodiment, an inlet valve retainer or threaded nut 53 having a
threaded
profile is positioned above upper portion 47, and engages a threaded profile
on fluid
inlet portion 19 to hold inlet valve cover 45 relative to discharge passage
43.
[0019] As illustrated also in Figure 5, upper portion 47 includes a top
surface 55 and a
bottom surface 57. Lower portion 49 also preferably includes a top surface 59
and a
bottom surface 61. Column 51 extends between bottom surface 57 of upper
portion
47 and top surface 59 of lower portion 49. As best :illustrated in Figure 5,
upper
portion 47, lower portion 49, and column 51 are all substantially
cylindrically shaped,
with each having their own respective diameters. In the preferred embodiment,
upper
portion 47 has a larger diameter than column 51 and lower portion 49, and
lower
portion 49 has a larger diameter than column 51. Fluid. being pumped from
cylinder
CA 02486223 2004-10-28
chamber 37 through discharge passage 43 is allowed to flow between upper and
lower
portions 47 and 49 around column 51.
[0020] Piston 35 reciprocates, or moves longitudinally toward and away from
cylinder 17, as crankshaft 25 rotates. As piston 35 moves longitudinally away
from
cylinder chamber 37, the pressure of the fluid inside chamber 37 decreases,
creating a
differential pressure across inlet valve 39, which actuates valve 39 and
allows the
fluid to enter cylinder chamber 37 through fluid inlet portion 19 from inlet
manifold
20. The fluid being pumped enters cylinder chamber 37 as piston 35 continues
to
move longitudinally away from cylinder 17 until the pressure difference
between the
fluid inside chamber 37 and the fluid in fluid inlet manifold 20 is small
enough for
inlet valve 39 to actuate to its closed position. As piston 35 begins to move
longitudinally toward cylinder 17, the pressure on the fluid inside of
cylinder chamber
37 begins to increase. Fluid pressure inside cylinder chamber 37 continues to
increase
as piston 35 approaches cylinder 17 until the differential pressure across
outlet valve
41 is large enough to actuate valve 41, which allows the fluid to exit
cylinder 17
through discharge passage 43 extending through fluid outlet and inlet portions
21, 19.
In the preferred embodiment, fluid is only pumped across one side of each
piston 35,
therefore reciprocating pump i 1 is a single-acting reciprocating pump.
[0021] During operation, inlet valve cover 45 experiences both upward and
downward forces from the fluid discharged from cylinder chamber 37 through
discharge passage 43, however the net force on valve cover 45 during the
suction and
discharge strokes is upward. During discharge, bottom surface 57 of upper
portion 47
experiences an upward force due to the fluid being discharged through
discharge
passage 43 around column 51, while top surface 59 of lower portion 49
experiences a
downward force from the fluid being discharged through discharge passage 43
around
column 51.
[0022] As mentioned above, in the preferred embodiment, upper portion 47 has a
larger diameter than lower portion 49. The forces experienced on bottom
surface 57
of upper portion 47 and top surface 59 of lower portion 49 are directly
proportional to
the surface area upon which the fluid discharge pressure in discharge passage
43 is
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applied. Due to the larger diameter of upper portion 47 compared to lower
portion 49,
the surface area upon which the fluid in discharge passage 43 applies pressure
is
larger. Therefore, the force upon upper portion 47 from. the fluid in
discharge passage
43 is larger than the downward force acting upon lower portion 49.
Consequently, a
net upward force is experienced by inlet valve cover 45 based upon the
discharge
fluid pressure located within discharge passage 43 flowing around column 51.
[0023] The combination of the upward force on the bottom surface 61 of lower
portion 49, and the net upward force from the fluid being discharged in
discharge
passage 43 on inlet valve cover 45 is greater than the downward force applied
on the
top surface 55 of upper portion 47 during both suction and discharge cycles of
reciprocating pump 11. Inlet valve cover 45 does not receive net oscillating
forces as
fluid is pumped into and out of cylinder chamber 37 because a net upward force
biases inlet valve cover 45 in a generally upward direction during both
suction and
discharge cycles of reciprocating pump 11. Having a net upward force on inlet
valve
cover 45 during both suction and discharge strokes of piston 35 thereby
reduces wear,
and increases the reliability and efficiency of reciprocating pump 11.
[0024] Offsetting the discharge and suction valves reduces the height of the
fluid end.
Also, the suction valves can be accessed without removing the discharge
valves.
[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, inlet
valve
cover 45 and threaded nut 53 could be combined to form a single part as
opposed to
two independent parts which would perform substantially the same function as
inlet
valve cover 45 described above.
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