U.S. patent application number 12/685490 was filed with the patent office on 2010-12-02 for reciprocating pump.
Invention is credited to Vladimir SCEKIC.
Application Number | 20100303655 12/685490 |
Document ID | / |
Family ID | 42352640 |
Filed Date | 2010-12-02 |
United States Patent
Application |
20100303655 |
Kind Code |
A1 |
SCEKIC; Vladimir |
December 2, 2010 |
RECIPROCATING PUMP
Abstract
A reciprocating pump including a sleeve comprising a first flow
path element and a plunger receivable in the sleeve is provided.
The plunger includes a fluid contact face and second flow path
element in fluid communication with the fluid contact face. The
sleeve and the fluid contact face define a compression chamber
comprising an inlet and an outlet. The sleeve and the plunger are
moveable relative to one another for adjusting overlap between the
first flow path element and the second flow path element for
diverting flow of fluid from the compression chamber and out of the
second flow path element during a discharge stroke to control flow
of fluid pumped out of the outlet.
Inventors: |
SCEKIC; Vladimir; (New
Westminster, CA) |
Correspondence
Address: |
OYEN, WIGGS, GREEN & MUTALA LLP;480 - THE STATION
601 WEST CORDOVA STREET
VANCOUVER
BC
V6B 1G1
CA
|
Family ID: |
42352640 |
Appl. No.: |
12/685490 |
Filed: |
January 11, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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61144367 |
Jan 13, 2009 |
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Current U.S.
Class: |
417/490 |
Current CPC
Class: |
F04B 39/10 20130101 |
Class at
Publication: |
417/490 |
International
Class: |
F04B 7/06 20060101
F04B007/06; F04B 39/10 20060101 F04B039/10 |
Claims
1. A reciprocating pump comprising: (a) a sleeve comprising a first
flow path element; (b) a plunger receivable in the sleeve, the
plunger comprising: i. a fluid contact face and ii. a second flow
path element in fluid communication with the fluid contact face;
wherein the sleeve and the fluid contact face define a compression
chamber comprising an inlet and an outlet; and wherein the sleeve
and the plunger are moveable relative to one another for adjusting
overlap between the first flow path element and the second flow
path element for diverting flow of fluid from the compression
chamber and out of the second flow path element during a discharge
stroke to control flow of fluid pumped out of the outlet.
2. A reciprocating pump according to claim 1, wherein the sleeve
comprises a sidewall, and the first flow path element comprises a
control hole formed in the sidewall of the sleeve.
3. A reciprocating pump according to claim 2, wherein the plunger
comprises a sidewall, and the second flow path element comprises a
channel formed in the sidewall of the plunger.
4. A reciprocating pump according to claim 1, wherein the sleeve
comprises a sidewall, and the first flow path element comprises a
channel formed in the sidewall of the sleeve.
5. A reciprocating pump according to claim 4, wherein the plunger
comprises a sidewall, the second flow path element comprises a bore
formed in the plunger, and a first end of the bore defines a
control hole formed in the sidewall of the plunger.
6. A reciprocating pump according to claim 5, wherein the sleeve
and the plunger are rotatable relative to one another about a
common axis for adjusting the overlap between the control hole and
the channel.
7. A reciprocating pump according to claim 6, wherein the overlap
is adjustable between a range of no overlap, whereby no fluid is
diverted away from the compression chamber, and complete overlap
whereby fluid is completely diverted away from the compression
chamber.
8. A reciprocating pump according to claim 7, wherein the sleeve is
rotatable.
9. A reciprocating pump according to claim 7, wherein the plunger
is rotatable.
10. A reciprocating pump according to claim 9, wherein the channel
is helical.
11. A reciprocating pump according to claim 3, wherein the control
hole is in fluid communication with an overflow chamber.
12. A reciprocating pump according to claim 6, wherein the channel
is in fluid communication with an overflow chamber.
13. A reciprocating pump according to claim 12, wherein the
overflow chamber is in fluid communication with a fluid port
upstream of the inlet.
14. A reciprocating pump according to claim 13, wherein the sleeve
comprises a hollow cylinder with an opening for receiving the
plunger.
15. A reciprocating pump according to claim 14, wherein the plunger
comprises a cylinder.
16. A reciprocating pump according to claim 15, wherein the control
hole is round.
17. A reciprocating pump comprising: (a) a sleeve comprising a
sidewall, the sidewall comprising a control hole; (b) a plunger
receivable in the sleeve, the plunger comprising: i. a fluid
contact face and ii. a helical channel in fluid communication with
the fluid contact face; wherein the sleeve and the fluid contact
face define a compression chamber comprising an inlet and an
outlet; and wherein the sleeve and the plunger are rotatable
relative to one another about a common longitudinal axis to adjust
the overlap between the control hole and the helical channel for
diverting flow of fluid from the compression chamber and out of the
control hole during a discharge stroke to control flow of fluid
pumped out of the outlet.
18. A reciprocating pump according to claim 17, wherein the sleeve
is rotatable.
19. A reciprocating pump according to claim 18, wherein the control
hole is in fluid communication with an overflow chamber.
20. A reciprocating pump according to claim 19, wherein the
overflow chamber is in fluid communication with a fluid port
upstream of the inlet.
21. A reciprocating pump according to claim 20, wherein the sleeve
comprises a hollow cylinder with an opening for receiving the
plunger.
22. A reciprocating pump according to claim 21, wherein the plunger
comprises a cylinder.
23. A reciprocating pump comprising: (a) a sleeve comprising a
sidewall, the sidewall comprising a helical channel; (b) a plunger
receivable in the sleeve, the plunger comprising: i. a fluid
contact face; ii. a sidewall; iii. a bore in fluid communication
with the fluid contact face, a first end of the bore defining a
control hole formed in the sidewall; wherein the sleeve and the
fluid contact face define a compression chamber comprising an inlet
and an outlet; and wherein the sleeve and the plunger are rotatable
relative to one another about a common longitudinal axis to adjust
the overlap between the control hole and the channel for diverting
flow of fluid from the compression chamber and out of the control
hole during a discharge stroke to control flow of fluid pumped out
of the outlet.
24. A reciprocating pump according to claim 23, wherein the sleeve
is rotatable.
25. A reciprocating pump according to claim 24, wherein the helical
channel is in fluid communication with an overflow chamber.
26. A reciprocating pump according to claim 25, wherein the
overflow chamber is in fluid communication with a fluid port
upstream of the inlet.
27. A reciprocating pump according to claim 26, wherein the sleeve
comprises a hollow cylinder with an opening for receiving the
plunger.
28. A reciprocating pump according to claim 27, wherein the plunger
comprises a cylinder.
29. A reciprocating pump comprising: (a) a sleeve; (b) a plunger
receivable in the sleeve, the plunger comprising a fluid contact
face, wherein the sleeve and the fluid contact face define a
compression chamber comprising an inlet and an outlet; (c) an
accumulator in fluid communication with the compression chamber for
diverting flow of fluid away from the compression chamber during a
discharge stroke to control flow of fluid pumped out of the output,
the accumulator comprising: i. a housing; ii. a control element
slidingly receivable in the housing, the control element comprising
a fluid contact face, the fluid contact face and the housing
defining an accumulation chamber; iii. a moveable stop configured
to adjustably define a maximum volume of fluid diverted to the
accumulation chamber by restricting movement of the control
element; and iv. a force means biasing the control element away
from the moveable stop.
30. A reciprocating pump according to claim 29 wherein the housing
comprises a hydraulic cylinder.
31. A reciprocating pump according to claim 30 wherein the control
element comprises a piston, and a travel of the piston is
adjustably restricted by the moveable stop.
32. A reciprocating pump according to claim 31 wherein a first
pressure exerted by the force means is less than a second pressure
sufficient to pump fluid out of the outlet.
33. A reciprocating pump according to claim 32 wherein the force
means comprises a spring.
34. A reciprocating pump according to claim 33 wherein the spring
comprises a compression spring.
35. A reciprocating pump according to claim 32 wherein the force
means comprises a source of fluid pressure.
36. A reciprocating pump according to claim 35 wherein the fluid
pressure is air pressure.
37. A reciprocating pump according to claim 31 wherein the moveable
stop comprises an annular ring disposed in the housing, wherein the
travel of the piston is restricted by abutment of a bearing surface
of the piston against the annular ring.
38. A method of controlling flow of fluid pumped by a reciprocating
pump during a discharge stroke, the method comprising: (a)
providing a reciprocating pump comprising a sleeve and a plunger
receivable in the sleeve, the sleeve comprising a first flow path
element, the plunger comprising a face and a second flow path
element in fluid communication with the face, wherein the sleeve
and the face define a compression chamber comprising an inlet and
an outlet, and the sleeve and the plunger are rotatable along a
common axis relative to one another; and (b) rotatably adjusting
overlap between the first flow path element and the second flow
path element to divert flow of fluid from the compression chamber
and out of the control hole.
39. A method according to claim 38 wherein step (b) comprises
rotating the sleeve.
40. A method according to claim 38 wherein step (b) comprises
rotating the plunger.
41. A method according to claim 40 further comprising: (c) allowing
fluid flowing out of the second flow path element to flow to an
overflow chamber.
42. A method according to claim 41 further comprising: (d) allowing
fluid from the overflow chamber to flow to a fluid port upstream of
the inlet.
43. A method of controlling flow of fluid pumped by a reciprocating
pump during a discharge stroke, the method comprising: (a)
providing a reciprocating pump comprising a compression chamber and
an accumulator in fluid communication with the compression chamber,
the accumulator comprising: i. a housing; ii. a control element
slidingly receivable in the housing, the control element comprising
a fluid contact face, the fluid contact face and the housing
defining an accumulation chamber; and iii. a moveable stop
configured to restrict movement of the control element to define a
maximum volume of the accumulation chamber; (b) moving the moveable
stop to adjust the maximum volume of the accumulation chamber to
control a volume of fluid diverted from the compression chamber to
the accumulation chamber.
44. A method according to claim 43 wherein step (a) comprises
providing a force means to bias the control element away from the
moveable stop.
45. A method according to claim 44 wherein step (a) comprises
maintaining a first pressure exerted by the force means to be less
than a second pressure sufficient to pump fluid out of an outlet of
the reciprocating pump.
46. (canceled)
47. (canceled)
Description
TECHNICAL FIELD
[0001] This invention relates to reciprocating pumps, and more
particularly reciprocating pumps having flow control for use for
example in mud-pumping and frac-pumping applications in the
oil-and-gas industry and in reciprocating gas compressors.
BACKGROUND
[0002] Reciprocating pumps are commonly used in applications where
high volumes of fluid need to be pumped at high pressures. Highest
efficiency reciprocating pumps are most commonly driven by a crank
or cam mechanism. Since any given crank or cam mechanism provides
for a constant stroke of the plunger, currently two methods are
usually used for controlling volumetric flow of these pumps: [0003]
changing the liner/plunger size (liners and plungers of smaller
diameter provide for less flow per stroke of the pump and vice
versa), [0004] changing the speed of the pump (slowing down the
pump will result in less "strokes per minute" which will result in
less flow of fluid and vice versa).
[0005] Both methods have serious limitations. Changing the liners
and plungers is labour-intensive and requires skilled labour, and
the pump must be taken out of service while the change is being
done, resulting in "down time" of the pump. Controlling the speed
may be practical within a limited range if a diesel or gas engine
is being used as a prime mover. However, if an electric motor is
used as a prime mover, very expensive and inefficient speed
controls need to be used, such as VFD or DC controllers. In order
to achieve an appropriate match between pumping requirements and
capabilities of the engines used as prime movers, expensive,
multispeed transmissions are often used, especially in frac-pumping
applications where such transmissions are often 6, 7 or even
8-speed units. Mud-pumping applications often use 2-speed
transmissions. In reciprocating gas compressor applications,
various factors influence the discharged flow of gas, including
temperature, humidity and the age of the engine.
[0006] Accordingly, there is a need for efficient and inexpensive
apparatus and methods for controlling the volumetric flow of fluid
discharged from reciprocating pumps.
SUMMARY
[0007] The present invention provides for "active" stroke control
of reciprocating pumps. Some or all of a plunger stroke can be
rendered ineffective by diverting fluid away from the compression
chamber of a pump. Controlling the amount of this ineffective
portion of the stroke is used to control the actual volume of fluid
being pumped out of a pump and downstream of a discharge valve.
[0008] One aspect of the invention provides a reciprocating pump
having a sleeve and a plunger receivable in the sleeve. The sleeve
has a first flow path element. The plunger has a fluid contact face
and a second flow path element in fluid communication with the
fluid contact face. The sleeve and the fluid contact face define a
compression chamber having an inlet and an outlet. The sleeve and
the plunger are moveable relative to one another for adjusting
overlap between the first flow path element and the second flow
path element for diverting flow of fluid from the compression
chamber and out of the second flow path element during a discharge
stroke to control flow of fluid pumped out of the outlet.
[0009] Another aspect of the invention provides a reciprocating
pump having a sleeve and a plunger receivable in the sleeve. The
sleeve has a sidewall with a control hole. The plunger has a fluid
contact face and a helical channel in fluid communication with the
fluid contact face. The sleeve and the fluid contact face define a
compression chamber with an inlet and an outlet. The sleeve and the
plunger are rotatable relative to one another about a common
longitudinal axis to adjust the overlap between the control hole
and the helical channel for diverting flow of fluid from the
compression chamber and out of the control hole during a discharge
stroke to control flow of fluid pumped out of the outlet.
[0010] A further aspect of the invention provides a reciprocating
pump having a sleeve and a plunger receivable in the sleeve. The
sleeve has a sidewall with a helical channel. The plunger has a
fluid contact face, a sidewall, and a bore in fluid communication
with the fluid contact face. A first end of the bore defines a
control hole formed in the sidewall. The sleeve and the fluid
contact face define a compression chamber with an inlet and an
outlet. The sleeve and the plunger are rotatable relative to one
another about a common longitudinal axis to adjust the overlap
between the control hole and the channel for diverting flow of
fluid from the compression chamber and out of the control hole
during a discharge stroke to control flow of fluid pumped out of
the outlet.
[0011] Another aspect of the invention provides a reciprocating
pump having a sleeve and a plunger receivable in the sleeve. The
plunger has a fluid contact face, and the sleeve and the fluid
contact face define a compression chamber with an inlet and an
outlet. The pump also includes an accumulator in fluid
communication with the compression chamber for diverting flow of
fluid away from the compression chamber during a discharge stroke
to control flow of fluid pumped out of the output. The accumulator
has a housing, a control element slidingly receivable in the
housing, a moveable stop, and a force means biasing the control
element away from the moveable stop. The control element has a
fluid contact face, and the fluid contact face and the housing
defining an accumulation chamber. The moveable stop is configured
to adjustably define a maximum volume of fluid diverted to the
accumulation chamber by restricting movement of the control
element.
[0012] A further aspect of the invention provides a method of
controlling flow of fluid pumped by a reciprocating pump during a
discharge stroke. The method includes the steps of:
(a) providing a reciprocating pump with a sleeve and a plunger
receivable in the sleeve, the sleeve having a first flow path
element, the plunger having a face and a second flow path element
in fluid communication with the face, wherein the sleeve and the
face define a compression chamber comprising an inlet and an
outlet, and the sleeve and the plunger are rotatable along a common
axis relative to one another; and (b) rotatably adjusting overlap
between the first flow path element and the second flow path
element to divert flow of fluid from the compression chamber and
out of the control hole.
[0013] Another aspect of the invention provides a method of
controlling flow of fluid pumped by a reciprocating pump during a
discharge stroke. The method includes the steps of:
(a) providing a reciprocating pump with a compression chamber and
an accumulator in fluid communication with the compression chamber,
the accumulator having a housing; a control element slidingly
receivable in the housing, the control element having a fluid
contact face, the fluid contact face and the housing defining an
accumulation chamber; and a moveable stop configured to restrict
movement of the control element to define a maximum volume of the
accumulation chamber; and (b) moving the moveable stop to adjust
the maximum volume of the accumulation chamber to control a volume
of fluid diverted from the compression chamber to the accumulation
chamber.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] In drawings which show non-limiting embodiments of the
invention:
[0015] FIG. 1 is a perspective see-through view of one embodiment
according to the present invention;
[0016] FIGS. 2A to 2C are side see-through views of the embodiment
shown in FIG. 1 at sequential stages of a discharge stroke from
bottom dead centre to top dead centre;
[0017] FIGS. 3A to 3C are side see-through views of the embodiment
shown in FIG. 1 at sequential stages of a discharge stroke from top
dead centre to top dead centre;
[0018] FIGS. 4A to 4C are side see-through views of the embodiment
shown in FIG. 1 at sequential stages of a discharge stroke from top
dead centre to top dead centre; and
[0019] FIG. 5 is a schematic view of one embodiment according to
the present invention.
LIST OF REFERENCE CHARACTERS
[0020] 10 reciprocating pump [0021] 12 plunger [0022] 14 sleeve
[0023] 16 overflow chamber [0024] 18 fluid contact face of plunger
12 [0025] 20 compression chamber [0026] 22 axis [0027] 24 control
hole [0028] 26 channel [0029] 100 reciprocating pump [0030] 112
plunger [0031] 114 sleeve [0032] 118 fluid contact face of plunger
112 [0033] 120 compression chamber [0034] 128 discharge valve
[0035] 130 discharge manifold [0036] 132 suction valve [0037] 134
suction manifold [0038] 136 hydraulic cylinder [0039] 138 fluid
port [0040] 140 piston [0041] 141 fluid contact face of piston 140
[0042] 142 stop [0043] 143 accumulation chamber [0044] 144 air
pressure source
DETAILED DESCRIPTION
[0045] It will be appreciated that numerous specific details are
set forth in order to provide a thorough understanding of the
exemplary embodiments described herein. However, it will be
understood by those of ordinary skill in the art that the
embodiments described herein may be practiced without these
specific details. In other instances, well-known methods,
procedures and components have not been described in detail so as
not to obscure the embodiments described herein. Furthermore, this
description is not to be considered as limiting the scope of the
embodiments described herein in any way, but rather as merely
describing the implementation of the various embodiments described
herein.
[0046] FIG. 1 shows a plunger 12, sleeve 14 and overflow chamber 16
of the "wet end" of a reciprocating pump 10 according to one
embodiment of the present invention.
[0047] The "power end" of plunger 12, shown at the bottom right of
FIG. 1, is connected to the cross-head of the pump (not shown)
which is, in turn, connected to the crankshaft via a connecting rod
(not shown). Rotary motion of the crankshaft is converted into a
linearly oscillating motion of plunger 12. Plunger 12 can move
between top dead centre ("TDC", or the position furthest away from
the crankshaft where the crank-throw and connecting rod are in
line) and Bottom Dead Centre ("BDC", or the position nearest to the
crankshaft where the crank-throw and connecting rod are in line).
Reciprocating pump 10 may also be a cam-driven pump. Movement from
TDC to BDC is referred to as the suction stroke; movement from BDC
to TDC is referred to as the discharge stroke. Reference herein to
the term "stroke" of the plunger will be to the discharge stroke
unless otherwise stated.
[0048] The "wet end" of plunger 12, shown at the upper left of FIG.
1, and in particular fluid contact face 18 is in contact with the
fluid being pumped and, with the surrounding walls of sleeve 14,
define compression chamber 20. Reference herein to the term "fluid"
includes liquids, including suspensions such as drilling mud, and
gases.
[0049] A typical reciprocating pump also comprises a pump-head
assembly which incorporates inlets or suction valves and outlets or
discharge valves (not shown), each allowing flow of fluid in one
direction only (either into the sleeve or out of it).
[0050] Reference is now made to FIGS. 2A to 2C. Sleeve 14 is
rotated about axis 22 such that a first flow path element, such as
control hole 24 formed in a sidewall of sleeve 14, overlaps with a
second flow path element, such as channel 26 formed in a sidewall
of plunger 12, throughout the discharge stroke. Channel 26 may be
helical. Reference herein to the term "channel" includes any
formation on and/or in the plunger through which fluid can flow
including cutouts, grooves, bores and the like. Fluid can thus be
diverted from compression chamber 20 through helical channel 26,
through control hole 24, into overflow chamber 16 and back to a
fluid port (not shown) upstream of the suction valve of pump 10. As
this diverted fluid flow is uninterrupted during the discharge
stroke, pump 10 runs completely unloaded, that is, no fluid is
actually pumped.
[0051] Reference is now made to FIGS. 3A to 3C. Sleeve 14 is
rotated about axis 22 such that control hole 24 overlaps with
helical channel 26 only at the beginning and the end of the
discharge stroke, allowing the path of flow to be diverted only for
these portions of the discharge stroke. Near the middle of the
stroke, control hole 24 faces a solid wall of plunger 12 thus
interrupting the diverted flow path and forcing the fluid to exit
compression chamber 20 through the discharge valve. Pump 10 thus
runs loaded only at the middle of the discharge stroke.
[0052] Reference is now made to FIGS. 4A to 4C. Sleeve 14 is
rotated about axis 22 such that control hole 24 overlaps with
helical channel 26 only near the middle of the stroke. Near the
beginning and the end of the stroke, control hole 24 faces the
solid wall of plunger 12 thus interrupting the diverted flow path
and forcing the fluid to exit compression chamber 20 through the
discharge valve. Pump 10 thus runs loaded only at the beginning and
end of the discharge stroke.
[0053] Sleeve 14 can also be rotated about axis 22 such that
control hole 24 never overlaps with helical channel 26. In this
position (not shown), flow of fluid cannot be diverted through
control hole 24, forcing all of the fluid to exit compression
chamber 20 through the discharge valve. Pump 10 thus runs fully
loaded throughout the discharge stroke.
[0054] Control of the diverted fluid flow can be achieved through a
number of combinations of channels and control holes. In some
embodiments a plurality of channels and/or control holes may be
provided. In some embodiments, the channel may be provided on the
sleeve and the control hole may be defined by a first end of a bore
formed in the plunger (with another end of the bore formed at the
fluid contact face of the plunger). In some embodiments, the
plunger (instead of the sleeve) may be rotated to effect flow
control. In some embodiments, both the plunger and the sleeve may
be rotated to effect flow control. The channels and control holes
may be any suitable size or shape that, in overlapping cooperation
during a discharge stroke, permit incremental, graduated or
step-wise control of fluid flow.
[0055] FIG. 5 shows a reciprocating pump 100 according to another
embodiment of the invention. Many components shown, notably plunger
112, sleeve 114, fluid contact face 118, and compression chamber
120 are similar in all aspects to equivalents components of
reciprocating pump 10. Outlet or discharge valve 128, discharge
manifold 130, inlet or suction valve 132 and suction manifold 134
are also shown. An accumulator, in the form of a hydraulic cylinder
136 in this particular embodiment, is connected to compression
chamber 120 by the means of a fluid port 138. A control element, in
the form of a piston 140 in this particular embodiment, can slide
dynamically inside hydraulic cylinder 136, and pushed back and
forth by pressure from fluid from compression chamber 120, towards
stop 142, and by pressure from a force means 144 biasing piston 140
away from stop 142. A fluid contact face 141 of piston 140 and
hydraulic cylinder 136 define an accumulation chamber 143.
[0056] Force means 144 may be any suitable source of pressure for
biasing piston 140 away from stop 142. In the illustrated
embodiment, force means 144 is a source of air pressure. In other
embodiments, force means 144 may, for example, be spring (e.g. a
compression spring), a deformable resilient member, or the
like.
[0057] Stop 142 is moveable and can be adjusted to restrict the
travel of piston 140 during the pump operation, thereby defining a
maximum volume of fluid that can be diverted to hydraulic cylinder
136 from compression chamber 120. Stop 142 may be any suitable
mechanical, electrical, or magnetic means for restricting the
travel of piston 140. In the illustrated embodiment, stop 142 is an
annular ring disposed in the hydraulic cylinder 136, wherein the
travel of piston 140 is restricted by abutment of a bearing surface
146 of piston 140 against the annular ring.
[0058] Before plunger 112 starts its discharge stroke, piston 140
will be moved away from stop 142 against the head of hydraulic
cylinder 136, driven by air pressure from air pressure source 144.
Suction pressure of the fluid is typically around 25 psi.
[0059] At start of discharge stroke of plunger 112, piston 140 will
start moving towards stop 142 by the pressure of fluid from
compression chamber 120. Since pressure in discharge valve 128 is
considerably higher than the air pressure from air pressure source
144 behind piston 140, no fluid will pass through discharge valve
128 until piston 140 hits stop 142. Once piston 140 hits stop 142,
pressure will start increasing in compression chamber 120 and
usable flow of fluid will start and last until the end of the
discharge stroke of plunger 112.
[0060] Once plunger 112 starts its suction stroke, piston 140 will
start moving away from stop 142 driven by air pressure from air
pressure source 144. Only once piston 140 hits the end of its
stroke opposite stop 142, suction valve will open 132 and "new"
fluid will enter compression chamber 120.
[0061] Flow control is thus effected by controlling the position of
stop 142; moving it closer to fluid port 138 of hydraulic cylinder
136 will reduce the volume of accumulation chamber 143 and thus
increase the effective pump flow; moving it away from fluid port
138 of hydraulic cylinder 136 will increase the volume of
accumulation chamber 143 and thus reducing the effective pump
flow.
[0062] The pumps described above are particularly suitable for use
in high pressure and/or high volume applications such as
mud-pumping and frac-pumping applications in the oil-and-gas
industry, as well as in reciprocating gas compressor applications.
Reciprocating pump 100 is particularly suitable for reciprocating
gas compressor applications.
* * * * *