Note: Descriptions are shown in the official language in which they were submitted.
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UNIBODY BYPASS PLUNGER AND VALVE CAGE WITH SEALABLE PORTS
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims the benefit of U.S. Provisional
Application No.
62/639,388, filed March 6, 2018, and is a continuation-in-part of U.S.
Application No.
15/048,491, filed February 19, 2016, which claims the benefit of U.S.
Provisional Application
No. 62/118,575, filed February 20, 2015.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention generally relates to gas lift devices for
rejuvenating low-
producing or non-productive oil or gas wells, and more particularly to
improvements in the
design and construction of bypass plungers.
[0004] 2. Background of the Invention and Description of the Prior Art
[0005] A conventional bypass plunger is a device that is configured to
freely descend and
ascend within a well tubing, typically to restore production to a well having
insufficient pressure
to lift the fluids to the surface. It may include a self-contained valve¨also
called a "dart" or a
"dart valve" in some embodiments--to control the descent and ascent. Typically
the valve is
opened to permit fluids in the well to flow through the valve and passages in
the plunger body as
the plunger descends through the well. Upon reaching the bottom of the well,
the valve is closed,
converting the plunger into a piston by blocking the passages that allow
fluids to flow through
the plunger. With the plunger converted to a piston, blocking the upward flow
of fluids or gas,
the residual pressures in the well increase enough to lift the plunger and the
volume of fluid
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above it toward the surface. Upon reaching the surface, the fluid is passed
through a conduit for
recovery, the valve in the plunger is opened by a striker mechanism, and the
plunger descends to
repeat the cycle.
[0006] In a typical bypass plunger the valve is similar to a poppet valve,
with a valve head
attached to one end of a valve stem, such as an intake valve of an internal
combustion engine.
The valve head, at the inward end of the stem, may be configured to contact a
valve seat within
the hollow body of the plunger. The stem protrudes outward of the bottom end
of the plunger
body. A clutch device may surround the stem of the valve to retard and control
the motion of the
stem and thereby maintain the valve in an open or closed configuration during
the descent or
ascent of the plunger, respectively. The valve thus moves between these two
positions to open
the flow passages at the surface when the plunger contacts the striker
mechanism, and to close
the bypass passages at the bottom of the well when the stem strikes the
bottom, usually at a
bumper device positioned at the bottom of the well. Descent of the plunger is
controlled by
gravity, which pulls it toward the bottom of the well when the valve is open.
Based on
characteristics of the well and the design of the plunger, fall speeds of the
plunger within the well
tubing will vary. If descent of the plunger is slow, shut-in or non-production
time of the well
may increase and production may be lost or delayed. However, if the descent of
the plunger is
too fast, the downhole bumper spring assembly and/or the plunger may be
damaged when the
plunger reaches the bottom of the well tubing. Typically, multiple designs and
configurations of
plungers must be manufactured and/or kept in stock to accommodate the various
and changing
conditions of the well.
[0007] This valve or "dart" may be held open or closed by the clutch-
typically a device that
exerts circumferential friction around the valve stem. The dart may be held
within a hollow cage
attached to the plunger by a threaded retainer or end nut at the lower end of
the plunger
assembly. Thus, the valve reciprocates between an internal valve seat (valve
closed) in a hollow
space inside the cage and the inside surface of the lower end of the cage
(valve open). A
conventional clutch is appropriate for some applications, especially when its
assembly is well
controlled to produce uniform assemblies. Such a clutch may be formed of a
bobbin split into
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two hemispherical halves and surrounded by one or two ordinary coil springs
that function as a
sort of garter to clamp the stem of the valve or dart between the two halves
of the bobbin,
thereby resisting the sliding motion of the stem within the bobbin. The clutch
assembly is
typically held in a fixed position within the cage. Each garter' spring is
wrapped around its
groove and the ends crimped together, typically in a hand operation that is
subject to some
variability in the tension around the bobbin halves and possible failure of
the crimped joint,
which could affect the reliability of the clutch when in a downhole
environment.
[0008] While
generally effective in lifting accumulated fluids and gas of unproductive
wells
such conventional bypass plungers tend to be complex and suffer from
reliability problems in an
environment that subjects them to high impact forces, very caustic fluids,
elevated temperatures
and the like. Various ways have been attempted to simplify construction of
bypass plungers,
improve their reliability and performance, and to reduce the cost of
manufacture. However,
failures remain common, and a substantial need exists to eliminate the causes
of these failures.
What is needed is a bypass plunger design that solves the structural problems
with existing
designs and provides a more reliable and efficient performance in the downhole
environment.
SUMMARY OF THE INVENTION
[0009]
Accordingly there is provided a bypass plunger comprising a unitary hollow
plunger
body and valve cage formed in one piece having first and second ends, the
valve cage formed at
the second end, and the valve cage having internal threads at its distal end
for receiving a
retaining nut having external threads at one end thereof; a poppet valve
having a valve head
connected to a valve stem, the poppet valve reciprocatingly disposed within
the valve cage such
that the valve head is oriented toward a valve seat foi ________________ tiled
within the hollow body; a retaining nut
having external threads formed in the outer surface thereof and corresponding
to internal threads
formed in the distal end of the valve cage to retain the poppet valve within
the valve cage; and at
least one helical groove formed for at least one-half revolution around the
outer surface of the
hollow plunger body for a portion of the length of the hollow body
approximately midway
between the first and second ends.
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[0010] In another embodiment, there is provided a bypass plunger comprising
a unitary
hollow plunger body and cage, the valve cage formed at a lower end thereof and
configured with
internal threads at its lower end for receiving a retaining nut having
external threads at one end
thereof; a poppet valve having a valve head connected to a valve stem and
reciprocatingly
disposed within the valve cage; and a retaining nut having external threads
for closing the lower
end of the valve cage to retain the poppet valve within the valve cage; and at
least two crimples
to lock the retaining nut to the valve cage.
[00111 In another embodiment there is provided a bypass plunger comprising
a unitary
hollow plunger body and valve cage, the valve cage formed at a lower end
thereof and
configured with internal threads at its lower end for receiving a retaining
nut having external
threads at one end thereof; a poppet valve having a valve head connected to a
valve stem and
reciprocatingly disposed within the valve cage, a retaining nut having
external threads for
closing the lower end of the valve cage to retain the poppet valve within the
valve cage; a
continuous helical groove machined into a central portion of the hollow body
midway between
upper and lower ends thereof and having a predetermined pitch, depth, and
profile according to
required spin and rate of descent of the bypass plunger through a well tubing;
first and second
crimple detents extending inward from the surface of the valve cage at the
second end of hollow
body and along first and second opposite radii of the valve cage into
corresponding relieved
spaces in the proximate external threads formed in the outer surface of the
retaining nut; and a
canted coil spring disposed within a circumferential groove formed into the
inside wall of the
retaining nut such that the canted coil spring exerts a substantial radial
clamping force on the
stem of the poppet valve, thereby &mining a clutch to retard the motion of the
poppet valve
between open and closed positions.
[0012] Accordingly there is provided a clutch assembly for a bypass plunger
having a valve
cage and a reciprocating dart valve, the dart valve having a round stem and
disposed within the
valve cage, the clutch assembly comprising: a partition nut, threadably
installed within an
internal thread of an open end of the valve cage following installation of the
dart valve in the
valve cage; a split bobbin assembly having first and second hemispherical
halves, each half of
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the split bobbin assembly having formed there around at least one
circumferential groove, and
the assembly installed on the stem of the dart valve; a coil spring disposed
in each
circumferential groove to secure the split bobbin assembly around a stem of
the dart valve,
thereby forming the clutch assembly; a retaining nut threadably installed
within the internal
thread of the valve cage following installation of the clutch assembly within
the valve cage, and
at least first and second crimples formed into the outer surface of the valve
cage and extending
into relieved spaces formed in an external thread formed on each one of the
retaining nut and the
partition nut.
[0013] In another embodiment there is provided a clutch for a bypass
plunger having a
reciprocating valve, comprising a clutch body formed as a circular split
bobbin assembly having
first and second halves, the assembly defined by a central axis, an inside
radius, an outside
radius, and first and second opposite faces normal to the central axis; a
circumferential groove
disposed in the surface defined by the outside radius of the split bobbin
assembly; and a canted-
coil spring disposed in the circumferential groove to secure the split bobbin
assembly around a
valve stem.
[0014] Accordingly there is provided a dart valve for a bypass plunger, the
dart valve
disposed to move reciprocatingly within a valve cage of the bypass plunger
between seated and
unseated positions and constrained by a clutch mechanism within the valve cage
or its retaining
nut, comprising a poppet valve comprising a valve stem and a valve head; a
valve head
connected to one end of the valve stem, the valve head including a sealing
face to make sealing
contact with a valve seat within the bypass plunger; and the valve stem
includes a predetermined
surface profile for moderating tension produced by the clutch mechanism during
the
reciprocating motion of the poppet valve
[0015] In another embodiment there is provided an improved valve dart
assembly for a one-
piece hollow plunger body and valve cage of a bypass plunger, the valve cage
formed at a lower
end of the hollow plunger body and configured with internal threads at its
open lower end, the
improvement comprising a poppet valve having a valve head connected to a valve
stem and
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reciprocatingly disposed within the valve cage; a retaining nut having
external threads at one end
thereof for engaging internal threads formed in the open lower end of the
valve cage to retain the
poppet valve within the valve cage, and a canted coil spring disposed within a
circumferential
groove formed into the inside wall of the retaining nut such that the canted
coil spring exerts a
substantial radial clamping force on the stem of the poppet valve, thereby
forming a clutch to
retard the motion of the poppet valve between open and closed positions.
[0016] In accordance with this disclosure, the exemplary embodiments
discussed herein may
include bypass flow ports that can be altered or sealed to control and/or
adjust the flow of fluids,
including oil, gas, and other fluids, through the plunger.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The accompanying drawings are part of the present disclosure and are
incorporated
into the specification. The drawings illustrate examples of embodiments of the
disclosure and, in
conjunction with the description and claims, serve to explain various
principles, features, or
aspects of the disclosure. Certain embodiments of the disclosure are described
more fully below
with reference to the accompanying drawings. However, various aspects of the
disclosure may
be implemented in many different forms and should not be construed as being
limited to the
implementations set forth herein.
[0018] FIG. 1 illustrates a side exploded view of one embodiment of a
bypass plunger
according to the present disclosure.
[0019] FIG. 2 illustrates a cross section view of the embodiment of FIG. l
as assembled.
[0020] FIG 3 illustrates a cross section detail view of the lower end of
the embodiment of
FIG. 2 with the valve shown in an open position.
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[0021] FIG. 4 illustrates a cross section detail view of the lower end of
the embodiment of
FIG. 2 with the valve shown in a closed position.
[0022] FIG. 5 illustrates a side cross section detail of an end (retaining)
nut and canted coil
spring for use with the embodiment of FIGS. 1-4.
[0023] FIG. 6 illustrates an end cross section detail of the end
(retaining) nut and canted coil
spring depicted in FIG. 5, for use with the embodiment of FIGS. 1-4.
[0024] FIG. 7 illustrates an enlarged version of FIG 3.
[0025] FIG. 8 illustrates an end cross section view of the embodiment
depicted in FIG. 7.
[0026] FIG. 9 illustrates a side view of a hollow body according to the
present disclosure
having a tight helix profile disposed in a central portion of the embodiment
of FIG. 1.
[0027] FIG. 10 illustrates a side view of a hollow body according to the
present disclosure
having an open helix profile disposed in a central portion of the embodiment
of FIG. 1.
[0028] FIG. 11 illustrates a first example of an alternative embodiment of
a plunger valve
clutch according to the present disclosure.
[0029] FIG. 12 illustrates a second example of an alternative embodiment of
a plunger valve
clutch according to the present disclosure.
[0030] FIG. 13 illustrates a third example of an alternative embodiment of
a plunger valve
clutch according to the present disclosure.
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[0031] FIG. 14 illustrates an alternate embodiment of the bypass plunger of
FIG. 1 that uses
a split bobbin clutch.
[0032] FIG. 15 illustrates a first example of an alternate embodiment of a
plunger valve dart
according to the present disclosure.
[0033] FIG. 16 illustrates a second example of an alternate embodiment of a
plunger valve
dart according to the present disclosure.
[0034] FIG. 17 illustrates a third example of an alternate embodiment of a
plunger valve dart
according to the present disclosure.
[0035] FIG. 18 illustrates a detail view of the profile of a feature of the
embodiment of FIG.
17.
[0036] FIG. 19 illustrates a die for use in a press to form a crimple used
in the embodiments
of FIGS. 3, 4, 7, and 8.
[0037] FIG. 20 illustrates an alternate embodiment to FIG. 4, showing a
split bobbin clutch
assembly for a bypass plunger within a valve cage.
[0038] FIG. 21 illustrates a cross section detail view of an alternate
embodiment of the lower
end of the embodiment of FIG. 3 with the valve shown in an open position.
[0039] FIG. 22 illustrates a cross section detail view of an alternate
embodiment of the lower
end of the embodiment of FIG. 4 with the valve shown in a closed position.
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[0040] FIG. 23 illustrates an embodiment of a plunger in accordance with
the disclosure with
the valve dart in an open position and at least one plug.
[0041] FIGS. 24 to 24C illustrate an embodiment of a plunger in accordance
with the
disclosure.
[0042] FIGS. 25 and 25A illustrate an embodiment of a plunger in accordance
with the
disclosure.
[0043] FIGS. 26 and 26A illustrate an embodiment of a plunger in accordance
with the
disclosure.
DETAILED DESCRIPTION OF THE INVENTION
[0044] In an advance in the state of the art, the novel bypass plunger
described herein with
the aid of the accompanying drawings yields improvements in a number of areas.
The result is a
novel unibody bypass plunger (aka unibody gas lift plunger) as disclosed
herein. The unibody
bypass plunger includes the one-piece hollow plunger body and the integral
valve cage formed at
its lower end. The valve cage assembly includes a valve dart and a clutch
mechanism enclosed
within the cage. A retaining nut (or end nut) that retains the valve dart and
clutch mechanism
within the cage completes the valve dart cage assembly. Novel features of the
present disclosure
provide reduction of manufacturing costs, and enhanced performance,
durability, and reliability,
advantages that may result through substantially greater simplicity of design
and construction.
The features of this novel combination are described as follows.
[0045] One feature is a one piece or unitary hollow body and cage (the
"unibody"
construction) with flow ports in the integral valve cage (disposed at the
lower end of the plunger
body) that can be altered to control the flow of fluid through the plunger on
descent. During
descent, the plunger falls through the well and any fluids therein. The fluids
flow though the
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angled ports in the valve cage and the hollow body of the plunger. The ports
in the cage may be
oriented at different angles, varied in number, relieved, sealed/plugged, etc.
to adjust the rate of
descent. This unibody design minimizes the number of parts and the number of
joints that must
be formed and secured, and the sealable flow ports minimize the number of
different plungers to
be manufactured and kept in inventory. One benefit of the one-piece or
"unibody" construction is
fewer parts to assemble and secure together, and the elimination of failures
in the mechanisms
used to secure the parts together.
[0046] The valve cage at the lower end and the end cap (if used) at the
upper end are mated
to the respective ends of the hollow plunger body with threaded joints and
secured with a crimp
("crimple") formed in at least two equally spaced locations around the hollow
body. The crimple
functions as an inward-formed dent that effectively indents the wall of the
valve cage portion of
the hollow body into a corresponding relief machined into the external threads
of the (smaller)
outside diameter of the retaining nut. The retaining nut (alternately "end
nut"), thus threadably
secured to the lower end of the valve cage, functions to close the open end of
the valve cage and
retain the poppet valve within the valve cage. The crimple feature eliminates
the need for
separate parts such as pins, screws, ball detents, lock nuts or washers, etc,
to lock a threaded joint
from loosening. The advantage of the crimple technique and mechanism is to
more reliably
prevent the inadvertent disassembly of the components secured to the bypass
plunger with screw
threads, thereby ensuring a true unibody bypass plunger that remains a single
unit throughout
many cycles of use. The term crimple is a contraction of the terms crimp and
dimple, to
characterize the crimp as approximating a crimp at a defined point as compared
with a
circumferential crimp.
[0047] The outer surface of the hollow plunger body of the present
disclosure may include a
series of concentric rings or ridges machined into the outer surface of the
hollow body for
approximately one third the overall length of the hollow body at each end. The
rings or ridges
thus provided act as a seal to minimize the clearance between the plunger and
the inside of the
well tubing through which it descends and ascends. In accordance with the
present disclosure,
between these two groups of concentric rings, one group at each end of the
hollow body, a series
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of concentric spiral (or helical) grooves (not unlike the "valleys" of screw
threads) may be
machined into the central portion of the outer surface of the hollow body. The
"central" portion
may typically (but not exclusively) be approximately the central one-third of
the length of the
hollow body. The pitch and profile of these spiral grooves may be varied
between a tight helix
and an open helix to vary the rate of spin of the plunger as it descends and
ascends. The purpose
of spinning the plunger is to prevent flat spots from forming on the outside
surface of the
plunger, which reduce the effectiveness and the useful life of the bypass
plunger. The cross
section profile of the grooves may also be varied to facilitate the spin rate.
[0048] The "clutch" of one embodiment of the present disclosure may consist
of a canted-
coil garter spring disposed within a circumferential groove inside the end
nut. In other words, no
bobbin is used, split or otherwise; just the canted coil spring that is
disposed within its groove
and wrapped 360 degrees around the stem of the valve dart. As used in the
inventive plunger, the
coils of the spring as formed are canted in the direction of its torroidal
centerline (i.e., a line
passing through the center of each coil of the spring) in a circumferential
direction around the
stem diameter. The coils of the canted coil spring, unlike a conventional coil
spring in which the
coils are disposed substantially at right angles to the centerline of the
spring, are disposed at an
acute angle relative to the centerline of the spring. This configuration
allows the spring to exert
tension at right angles to its centerline against the outside diameter surface
of the valve dart stem.
This property is enhanced when the outer diameter of the canted-coil spring is
constrained by a
cylindrical bore or in a groove surrounding the spring. The surface of the
valve dart stem in one
embodiment is preferably machined to a surface roughness of approximately 8 to
50
microinches, a standard specification for a very smooth finish. The canted
coil spring is supplied
in a 360 degree form with its ends welded together (thereby forming a
torroidal shape), enabling
it to be dimensioned to fit within a machined groove in the end nut or
retaining nut. Advantages
of this design include elimination of the bobbin components and greater
durability,
[0049] In the appended drawings, reference numbers that appear in more than
one figure
refer to the same structural feature. The drawings depict at least one example
of each
embodiment or aspect to illustrate the features of the present disclosure and
are not to be
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construed as limiting the disclosure thereto. In addition, several alternative
embodiments of a
clutch mechanism for a plunger valve that utilizes canted-coil springs, and
several alternative
embodiments of a plunger valve dart having different valve stem profiles are
included to suggest
the scope of modifications that may be made to these components without
departing from the
concepts employed in the present disclosure. It should be understood that the
term "plunger dart"
or simply "dart" may also be named a poppet valve or a valve dart herein, all
of which refer to
the same component.
[0050] FIG. 1 illustrates a side exploded view of one embodiment of an
integrated, unibody
bypass plunger according to the present disclosure. The unibody bypass plunger
10 is formed as
a single hollow plunger body 12 machined from a suitable material such as a
stainless steel alloy.
Such materials are well known in the art. Forming the hollow plunger body as a
single piece
simplifies construction by reducing the number of parts to be connected
together with screw
threads, thereby reducing the opportunities for failure when a threaded joint
fails. Further, the
profiles of the flow ports in the valve cage 16, the sealing rings 22, 26, and
the centralized helix
24 may all be readily tailored during manufacture for a specific application.
The plunger body
includes the following sections: an ID fishing neck 14, an upper section of
sealing rings 22, an
intermediate or central section of helical ridges or grooves 24, a lower
section of sealing rings
26, and a valve cage 16 for enclosing and retaining a poppet valve or valve
dart 32.
[0051] The valve cage 16 includes a plurality of flow ports 18 disposed at
typically two to
four equally-spaced radial locations around the valve cage 16, and in some
embodiments may
include, for example, one to eight or more flow ports 18 depending on the
intended application.
The flow ports 18 may be oriented at different angles, varied in number,
relieved, sealed, and/or
plugged to adjust flow rates through the plunger 10 and, thereby,
control/optimize fall speed of
the plunger 10. In exemplary embodiments, one or more of the flow ports 18 may
be sealed by a
plug 19 (FIG. 23), as described below.
[0052] In the illustrated embodiment, two or more crimples 20 to be
described may be
positioned as shown near the lower end of the hollow body 12 at valve cage 16.
The crimple 20
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provides a mechanism to lock a retaining nut or end nut 40 threaded on the
open, lower end of
the valve cage 16. The hollow body 12 may further include wear grooves 30
disposed at selected
ones of the sealing rings 22, 26 as shown. Further, disposed within the
retaining or end nut 40
when the bypass plunger is assembled is a canted-coil spring 42 that functions
as a clutch. This
novel clutch design, which does not require use of a bobbin or similar
structure, will be described
herein below.
[0053] Continuing with FIG. 1, the assembly of the bypass plunger 10
includes a valve dart
32 inserted head-end first through the valve cage 16 into the lower end of the
hollow body 12.
The valve head 36 and its sealing face 38 form a poppet valve head at the end
of stem 34. When
installed in the hollow body 12, the sealing face 38 of the poppet valve or
dart 32 is shaped to
contact a valve seat 48 machined into the internal bore 52 of the hollow body
12 as shown in
FIG. 4 that depicts the valve dart 32 in a closed position. The valve dart 32
may be retained
within the valve cage 16 by the end nut 40 that may be installed in the lower
end of the valve
cage 16 and secured by screw threads 28 (See FIG. 7). The end nut 40 includes
in this
embodiment an external circular groove 44 around part of its threaded portion.
This groove 44
provides a relieved space so that a crimple 20 to be described may extend into
the groove 44 to
lock the external threads of the end nut 40 to corresponding internal threads
in the lower end of
the valve cage 16. The end nut 40 also preferably includes a canted-coil
spring 42 (to be
described) disposed into an internal circumferential groove 50 (See FIG. 5).
The canted-coil
spring 42 replaces a conventional clutch often used with dart-equipped
plungers and provides a
simpler and more effective structure to retard or brake the motion of the
valve stem as it moves
between open and closed positions.
[0054] FIG. 2 illustrates a partial cross section view of the embodiment of
FIG. I as
assembled to depict the relationship of several internal features of the
bypass plunger 10. The
valve dart 32, shown in its open position for descent, is confined within the
valve cage 16 by the
retaining nut 40. The canted-coil spring 42 surrounds the stem 34 of the valve
dart 32 to retard its
motion within the valve cage 16. The canted-coil spring 42 is retained within
the circumferential
groove 50 machined into the inner bore of the retaining nut 40, as more
clearly shown in FIGS.
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3-6. The inner bore 52 of the hollow body 12 includes valve seat 48 and flow
ports 18 cut
through the wall of the valve cage 16. One example of the profiles of the
sealing rings 22, 26 and
the helical grooves 24 are also depicted in FIG. 2.
[0055] FIG. 3 illustrates a cross section detail view of the lower (valve
cage 16) end of the
embodiment of the bypass plunger 10 shown in FIG. 2 with the valve dart 32 in
an open position.
In the open position, the valve dart 32 is positioned such that the flow ports
18 are unobstructed
and fluids and/or gases are permitted to flow through the plunger 10 (bypass
condition) during
descent of the plunger 10 within the well tubing. FIG. 3 also depicts the use
of a crimple 20 that
deforms the wall of the valve cage 16 so that an extended portion of the
crimple 20--the crimp
21, formed as a dent in the outer surface of the valve cage 16--protrudes into
a relieved portion
44 of the screw threads of the retaining or end nut 40. Persons skilled in the
art will appreciate
that the relieved portion 44 may be machined as a drilled hole of limited
depth or a punched
opening that may be round, oval, or rectangular in shape. In some cases, the
formation of the
crimple on the outer surface of the valve cage may extend into the threads of
the retaining nut 40
sufficiently to prevent the retaining nut from loosening.
[0056] The crimple 20 thus functions similar to a set screw or a pin to
prevent the loosening
of the screw threads. This feature is shown and described in greater detail
for FIGS. 7 and 8. In
the claims or in the description of the present disclosure, which includes a
one-piece or
"unibody" hollow plunger body and valve cage, the crimple feature may be
variously described
and understood as being disposed in the "hollow body" or in the "valve cage"
portion of the
hollow body. Moreover, persons skilled in the art will recognize that the
crimple feature is a
technique that may be used in place of set screws, pins, etc., to secure
threaded components from
turning relative to each other. For example, end nuts at either end of a
plunger body or a bumper
spring or other similarly constructed device, may employ a crimple as
described herein to useful
advantage.
[0057] FIG. 4, which is similar to FIG. 3, illustrates a cross section
detail view of the lower
end of the embodiment of the valve cage (16) portion of the bypass plunger
shown in FIG. 2 with
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the valve dart 32 in a closed or seated position, with the sealing face 38 of
the valve head 36
seated against the valve seat 48 inside the valve cage 16, and the opposite
end of the valve dart
32 slightly retracted--e.g., no more than about 0.030 inch--within the end of
the retaining nut 40.
In the closed position, the valve dart 32 obstructs flow of fluids and/or
gases through the flow
ports 18 and the plunger body 12, preventing a bypass or flow-through
condition, thus enabling
the plunger to ascend to the surface.
[0058] FIG. 5 illustrates a side cross section detail of the end
(retaining) nut 40 and the
canted-coil spring 42 for use with the embodiment of FIGS. 1-4. In this
illustrated embodiment
the canted-coil spring 42 is disposed within a circumferential groove 50
inside the end nut 40.
The canted-coil spring 42 provides a clutch action on the stem 34 of the valve
dart 32 without
using a bobbin, split or otherwise. Only the canted-coil spring 42 that is
disposed within its
groove 50 and wrapped 360 degrees around the stem 34 of the valve dart 32 acts
to restrain the
motion of the dart valve 32. As used in the illustrated bypass plunger 10, the
coils of the spring
42 as formed are canted in the direction of its centerline, that is, in a
circumferential direction
around the stem 34 diameter.
[0059] The coils of the canted-coil spring, unlike a conventional coil
spring in which the
coils are disposed substantially at right angles to the centerline of the
spring, are disposed at an
acute angle relative to the centerline of the spring 42. This configuration
allows the canted coils
of spring 42 to exert tension radially inward at right angles to its
centerline against the outer
surface of the valve stem 34. The particular specifications of the canted-coil
spring, such as the
material used for the spring wire, its overall diameter, the diameter of the
coils, the acute angle
the coils form relative to the centerline of the spring, etc., may be selected
to suit the particular
dimensions of the bypass plunger, its expected environment, and other
conditions of use. The
performance of the canted-coil spring design is facilitated by the surface
finish provided on the
surface of the stem 34. Optimum performance is provided when the surface
finish, preferably
produced by machining, is held within the range of 8 to 50 microinches.
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[0060] Advantages of this bobbinless, canted-coil spring design include at
least the
following: (a) reduction in the number of components required to provide the
clutch function; (b)
the canted-coil spring 42 is supported in a more confined space, reducing the
likelihood of failure
during hard impacts; (c) the need to assemble a split bobbin-with-garter
springs clutch is
eliminated--the canted-coil spring is simply inserted into its circumferential
groove 44; and (d)
the use of a conventional clutch bobbin assembly is eliminated. These
advantages arise from the
simplicity and the construction of the canted-coil spring.
[0061] Unlike a typical garter spring, which as supplied is simply a coil
spring that must be
formed into a circle and the ends typically crimped together (a hand-assembly
operation that is
prone to errors such as in cutting to length and crimping, etc.), the canted-
coil spring 42 is
supplied to specification with the ends welded and the circular, torroidal-
form coil properly
dimensioned and configured for the particular application. Also unlike the
garter spring, the
canted-coil spring 42 need only be inserted into the circumferential groove 50
in the end nut 40,
while the garter spring must be assembled onto the split bobbin; again a more
complex hand-
assembly operation. Thus the use of the canted-coil spring 42 ensures a leaner
manufacturing
process of a bypass plunger 10 that is substantially more reliable because of
the more durable
spring, and the more consistent tension it provides. These features markedly
improve the impact
resistance of the shifting mechanism (the valve cage 16, end nut 40, and
canted-coil spring 42) of
the unibody bypass plunger 10 disclosed herein.
[0062] Continuing with FIG. 5, the surface of the stem 34 is preferably
machined and
finished to a surface roughness of approximately 8 to 50 microinches. The
combination of the
radial tension and the specified surface finish provides the appropriate
amount of friction to
control the motion of the valve dart 32 between the open and closed positions
of the stem 34 of
the valve dart 32. As noted above, the advantages of this design include
elimination of the
bobbin components and greater durability.
[0063] There are several alternate surface finishes to be illustrated and
described (See FIGS.
15 through 18)--combinations of recesses, grooves, undercuts, and surface
roughness--that may
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be applied to the stem 34 of the valve dart 32 to limit or control the
shifting of the valve dart 32
during operation of the bypass plunger 10. These features can improve the
operation of the
bypass plunger under a variety of conditions while descending or ascending in
the well tubing.
For example, recesses such as snap ring grooves may be located at strategic
locations along the
stem 34 to prevent the stem 34 from sliding too easily within the canted-coil
spring 42 or restrain
the sliding when the bypass plunger encounters a condition that it might
otherwise interpret as
contacting the striker at the surface or the bumper spring at the bottom of
the well.
[0064] FIG. 6 illustrates an end cross section detail of the end
(retaining) nut 40 and canted-
coil spring 42 surrounding the stem 34 of the valve dart 32 for use with the
embodiment of FIGS.
1-4. As shown, the canted coil spring is supplied in a 360 degree form that is
dimensioned to fit
within the machined groove 50 in the end nut 40.
[0065] FIG. 7 illustrates an enlarged version of FIG. 3 to depict the form
of the crimple 20
used to lock the retaining or end nut 40 to the valve cage 16. The crimple
embodiment is an
effective technique for locking the threaded joint between the retaining or
end nut 40 and the
valve cage 16. This form of locking the joint also acts to prevent loosening,
thereby extending
the life of the joint. As shown, the crimple 20 is formed as a detent 20, 21
into the outer surface
of the valve cage 16. The dent or crimple 20 extends radially inward through
the threads 28 of
the retaining or end nut 40 and valve cage 16 and into the circumferential
recess 44 (shown in
cross section in FIG. 7). The detent 20, 21 may be approximately rectangular
in cross section to
enable the narrower dimension to extend more readily into the recess 44.
[0066] Alternatively, the profile of the detent 20, 21 may be approximately
conical in form,
as though formed by a center punch having a conical point In practice, the
crimple detent 20, 21
may be formed using a press as is well-known in the art. One preferred example
of a die used in
a press to form the crimple is illustrated in FIG. 19 to be described. The
detent 20, 21 is
preferably placed in at least two locations, on opposite sides of the valve
cage 16--i.e.,
approximately 180 degrees apart around the body of the valve cage 16 as shown
in FIG. 8, which
illustrates an end cross section view of the embodiment depicted in FIG. 7.
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[0067] FIG. 9 illustrates a side view of a hollow body bypass plunger 60
according to the
present disclosure. The plunger of FIG. 1 is depicted in FIG. 9 with a groove
surrounding the
central portion of the body of the plunger and forming a tight helix profile
62. FIG. 10 illustrates
a side view of a hollow body bypass plunger 70 according to the present
disclosure having a
more open helix profile 72 formed of several grooves, also disposed in a
central portion 24 of the
plunger 70. The helical feature disposed in the central portion 24 of the
plungers 60, 70 may be
called a centralized helix that is formed to cause the plunger to rotate as it
ascends and descends
or travels up and down through the well bore. Since the seal provided by the
sealing rings 22, 26
is not total, fluids and gases escape past the sealing rings 22, 26. As the
plunger 60, 70 passes
through the well bore, the fluids and gases impart a torque to the plunger 60,
70 by the
mechanism of the helical grooves 62, 72 respectively. The result is a
reduction in the occurrence
of flat spots along the outside diameter of the sealing rings 22, 26 of the
body of the plunger 60,
70 and consequent longer life.
[0068] The continuous helical groove machined into the central portion of
the hollow body
midway between the upper and lower ends thereof may have a predetermined
pitch, depth, and
profile. The variation in the pitch of the helical grooves 62, 72 as shown in
FIGS. 9 and 10
provides a means of varying the rate of spin imparted to the bypass plungers
60, 70. In the
example of FIG. 9, a single helical groove 62 encircles the body of the
plunger 60 from one up to
as many as eight times. Lengthening the fluid path around the plunger 60 tends
to reduce the spin
rate of the plunger 60. In the example of FIG. 10, a plurality of helical
grooves, typically three or
four (but could be from one to as many as twelve) spaced at equal intervals
around the plunger
body 60 provides a shorter fluid path around the plunger 70 to increase the
spin rate of the
plunger 70 In applications where the number of helical grooves is greater than
the typical
number of three to four, the width of the helical grooves may be
proportionately narrowed as the
number of grooves is increased.
[0069] It is important to note that the central helix 62, 72 is positioned
mid-way between the
sealing rings so as not to impair the sealing function of the sealing rings
22, 26 yet still provide a
mechanism to cause the plunger 60, 70 to rotate during its up-and-down
travels. Moreover,
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experience has shown that placing the helical grooves near the ends of the
plunger body 60, 70
causes the outside diameter of the plunger to wear faster, reducing the
profile depth and
effectiveness of the helical grooves and reducing the life of the bypass
plunger 60, 70.
[0070] The concept of the centralized helix may also be used with good
effect in sand
plungers used in sand-producing wells by improving the movement of the plunger
through sand-
bearing fluid because of the rotation imparted to the sand plunger. The
rotation may also tend to
keep the helical grooves--and the space between the plunger body and the well
tubing free of
sand build-up through the effects of centrifugal force.
[0071] One of the usual components of a dart or poppet valve as used in a
bypass or gas-lift
plunger is some form of clutch to restrain the motion of the dart, thereby
ensuring the efficient
operation of the dart in controlling the operation of the plunger. A
conventional split-bobbin
clutch may employ a circular bobbin split into two equal hemispherical halves
to enable
convenient assembly around the stem of the dart or poppet valve. The two
halves are generally
held against the stem by one or more (usually two) so-called "garter springs"
disposed in grooves
surrounding the bobbin assembly. Each bobbin half encircles the stem for
slightly less than a full
180 degrees, so that the inside surface of each bobbin half may make direct
contact with the stem
of the dart under the tension provided by the garter spring(s). The clutch
assembly is generally
secured within the body of the plunger through which the dart reciprocates
during its use. The
clutch, through the friction exerted against the stem, acts to damp the motion
of the stem within
the bypass plunger so that it remains in the required closed or opened
position during ascent or
descent respectively through the well tubing.
[0072] FIGS. 11, 12, and 13 illustrate several alternative embodiments of a
split-bobbin
clutch assembly for use with darts (or dart valves or poppet valves) to
restrain the motion of the
dart and to support the dart in its closed and open positions within a bypass
plunger. These
embodiments differ from conventional clutches in the type of spring used in
place of a garter
spring and the location of the canted-coil spring on the bobbin assembly.
Conventional split
bobbin clutches typically use one or two ordinary coil springs that are
wrapped around the
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bobbin assembly and its ends crimped together to form a circular loop around
the bobbin. The
spring tension of an ordinary coil spring, that acts like a rubber band around
the bobbin, exerts an
inward force to clamp the bobbin halves around the dart stem. In contrast, the
springs used in the
clutches illustrated in FIGS. 11, 12, and 13 have their coils canted at an
acute angle with the
centerline of the spring. That is, the coils of the spring all slant in the
same direction, and the
ends of the canted-coil spring are permanently secured together by welding
during the
manufacture of the canted-coil spring. The tension against the stem results
from the inherent
tension of the slanted (canted) coils, not from the tension in a coil spring
stretched around the
bobbin and stem. Thus, the spring merely needs to be looped over the bobbin
halves during
assembly. This results in uniform unit-to-unit clutch assemblies, which
translates to greater
dependability of the clutch perfolinance under downhole conditions.
[0073] The split bobbins of FIGS. 11, 12, and 13 differ from one another in
the location of
grooves for supporting the canted-coil spring embodiment. FIG. 11 has the
grooves positioned in
each side face of the bobbin halves as shown. FIG. 12 depicts the grooves
formed in the faces of
the bobbin but intersecting the outer diameter of the bobbin so that the
grooves are formed along
the outer edges of the bobbin. FIG. 13 shows a single groove formed around the
perimeter of the
bobbin, with a canted-coil spring installed in the groove. In this embodiment,
a bobbin could be
constructed with more than one spring installed; thus FIG. 13 is provided here
to illustrate the
concept.
[0074] It is possible to use a conventional coil spring in the embodiments
depicted in each of
FIGS. 11, 12, and 13. However, several advantages are provided by the use of a
canted-coil
spring to hold the bobbin halves together. (1) The manufacturing process of
assembling the
bobbins is much simpler, involving substantially less hand work and
opportunity for errors in
assembly. (2) This configuration provides a more consistent tension because
the variation
between individual ones of the canted-coil springs can be held to a much
closer tolerance than
ordinary coil springs that must be individually assembled on the bobbin. (3)
The impact
resistance of the clutches assembled with canted-coil springs is greater
because the springs can
be specified with stronger spring constants, the ends are more securely
fastened, and the inward
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tension exerted by the canted-coil configuration can be greater and more
closely controlled.
These advantages provide superior service life and reliability, and lower
operating costs,
especially important in downhole conditions characterized by high impacts and
corrosive
sub stances.
[00751 FIG. 11 illustrates a first example of an alternative embodiment of
a plunger valve
clutch according to the present disclosure. The clutch 80 is assembled from
first 82 and second
84 halves of a split bobbin assembly 86. A first canted-coil spring 88 is
installed in groove 90,
and a second canted-coil spring 92 is installed in a similar groove 94 that is
visible in the cut-
away portion of the figure. When assembled on a valve stem, the clutch 86
includes a gap 96
between the first 82 and second 84 halves of the split bobbin assembly 86. The
gap 96 ensures
that the tension exerted on the stem by the clutch 80 will be maintained.
[00761 FIG. 12 illustrates a second example of an alternative embodiment of
a plunger valve
clutch according to the present disclosure. The clutch 98 is assembled from
first 100 and second
102 halves of a split bobbin assembly 104. A first canted-coil spring 106 is
installed in groove
108, and a second canted-coil spring 110 is installed in a similar groove 112
that is not fully
visible in FIG. 12 because it is installed on the opposite face of the split
bobbin assembly 104.
When assembled on a valve stem the clutch 98 includes a gap 114 between the
first 100 and
second 102 halves of the bobbin assembly 104. The gap 114 ensures that the
tension exerted on
the stem by the clutch 98 will be maintained.
[00771 FIG. 13 illustrates a third example of an alternative embodiment of
a plunger valve
clutch according to the present disclosure. The clutch 116 is assembled from
first 118 and second
120 halves of a split bobbin assembly 122. A first canted-coil spring 124 is
installed in groove
126. If another canted-coil spring is desired, a second groove would be
required. When
assembled on a valve stem the clutch 116 includes a gap 128 between the first
118 and second
120 halves of the spilt bobbin assembly 122. The gap 128 ensures that the
tension exerted on the
stem by the clutch 116 will be maintained.
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[0078] It should be appreciated by persons skilled in the art that a single
canted-coil spring is
adequate for most applications because the spring can be manufactured within a
given size
constraint and spring-constant as assembled to exert the required inward
radial force and it is
thus not required to perform trial and error operations to select the proper
springs.
[00791 FIG. 14 illustrates an alternate embodiment of the present
disclosure that is similar to
the embodiment of FIG. 1 except FIG. 14 is shown with a split bobbin clutch
assembly 140
instead of the canted coil spring 42 as shown in FIG. 1. The clutch assembly
140, which is an
assembly of the split bobbin halves 140A, 140B, is shown without a garter
spring for clarity. The
split bobbin halves 140A, 140B may be encircled by one garter (or canted coil)
spring as shown
or two garter springs in the manner of FIGS. 11, 12, and 13. A partition nut
142, for retaining the
clutch assembly 140 between the retaining or end nut 40 and the partition nut
142, is shown
adjacent to the clutch bobbin halves 140A, 140B. The partition nut 142 is
provided to ensure the
clutch assembly 140 (and garter or canted coil spring) remains in position
between the end nut 40
and the partition nut 142.
[0080] FIGS. 15 through 18 illustrate several embodiments of the valve stem
34 portion of
the valve dart. These embodiments describe surface finishes or profiles
including several
examples of alternative surface profiles for moderating the reciprocating
motion of the valve
stem within the clutch structure of the unibody bypass plunger 10.
[0081] FIG. 15 illustrates a first example of an alternate embodiment of a
plunger valve dart
150 according to the present disclosure. The valve dart 150 includes first 152
and second 154
grooves that encircle the stem 34 near each end of the stem 34. The grooves in
the illustrated
embodiment are formed as snap-ring grooves, a standard form for retaining snap
rings that is
easily produced during manufacture of the valve dart 150. In the illustrated
embodiment, the
snap-ring grooves, in cross section, may be formed as a 0.094 inch radius
(R.094, or,
approximately 0.10") into the stem 34, to a depth of approximately 0.01 inch.
For other
embodiments requiring other bypass plunger body diameters, these dimensions
may be varied or
scaled according to the dimensions of the bypass plunger and the canted-coil
spring to be used
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with the bypass plunger. The first groove 152 provides a retention feature to
position the canted
coil spring 42 to retain the valve dart 150 closed as the plunger ascends. The
first groove 152
acts to resist vibration effects that might tend to open the valve during
ascent. Such intermittent
opening and closing of the valve dart reduces the efficiency of the plunger in
lifting the fluids
and gas to the surface. Similarly, the second groove 154 acts to resist
vibration effects that might
tend to close the valve during descent. Such intermittent closing of the dart
valve 150 reduces the
speed of the plunger as it descends from the surface to the bottom of the well
to begin a new lift
cycle The stem 34 is preferably machined to a surface roughness of 8 to 50
microinches as in the
embodiment shown in FIG. 5.
[0082] FIG. 16 illustrates a second example of an alternate embodiment of a
plunger dart
valve according to the present disclosure. The dart valve 160 includes first
162 and second 164
grooves or recessed regions that encircle the stem 34 near each end of the
stem 34. The first
groove 162 in the illustrated embodiment is formed as a snap-ring groove, a
standard form for
retaining snap rings that is easily produced during manufacture of the dart
valve 160. The first
groove 162 is provided to enable the canted-coil spring to retain the dart
valve 160 in a closed
position for ascent of the plunger. The second groove or recessed region 164
at the other end of
the stem 34 near the valve head 36 is similar to the first groove or recessed
region 162 except
that it is substantially wider along the length of the stem 34 to provide a
predetermined amount
of freedom for the dart valve to open even if it contacts the striker at the
surface with less than
the expected amount of upward-directed force. The longer intermediate length
166 of the stem
34 is similarly recessed from the nominal stem diameter. This feature, by
allowing the valve dart
160 to gain momentum as it moves within the valve cage 16, facilitates the
movement of the
stem 34 of the dart valve 160 through the restraining action of the canted-
coil spring 42 as the
dart valve moves between open and closed positions. The surface is preferably
machined to a
surface roughness of 8 to 50 microinches as in the embodiment shown in FIG. 5.
[0083] FIG. 17 illustrates a third example of an alternate embodiment of a
plunger dart valve
according to the present disclosure. In this embodiment of the dart valve 170,
substantially the
entire length of the stem 34 includes a surface profile 172 formed of closely-
spaced alternating
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ribs and grooves having a substantially uniform profile--for instance
resembling a sinusoidal
wave in the illustrated example--as depicted in the detail view of FIG. 18 to
be described. This
dart valve 170 is designed for use with the split bobbin clutch designs
illustrated in FIGS. 11, 12,
and 13 described herein above.
[0084] FIG. 18 illustrates a detail view of the profile of a feature of the
embodiment of FIG.
17, wherein the alternating rib-and-groove profile is more clearly shown. The
surface profile 172
of the stem 34, shown in cross section in FIG. 17 illustrates both the ribs
174 and the grooves
176 formed according to a radius R and separated by a spacing S. The radius R
may be within
the range of 0 020 inch to 0.150 inch and the spacing S between an adjacent
crest and trough
may be within the range of 0.020 inch to 0.075 inch. The values of R on a
particular valve stem
should be constant and the values of S on a particular valve stem should be
constant.
[0085] FIG. 19 illustrates one example of a die for use in a press to foun
a crimple used in
the embodiments of FIGS. 3, 4, 7, and 8. The body 200 of the die includes a
reduced diameter
shank 202 that is shaped at its end to form the crimple 20 in the outer
surface of the valve cage
16 portion of the unibody bypass plunger body 12. The crimple 20 is shown in
detail in FIGS. 3,
4, 7, and 8. The crimple 20, an indentation into the outer surface of the
valve cage 16, is
produced by the shape of the crimple blade 204. The crimple blade 204 as
shaped includes a
major radius 206, a minor radius 208, and a fillet radius 210. The major
radius 206 shapes the
blade 204 to the radius of the plunger body 12 at the location of the crimple
20. The major radius
is formed to a radial dimension slightly larger than the body of the plunger
to be formed. Thus,
when the blade 204 contacts the plunger body and begins to form the crimple
20, the stresses
produced in the metal plunger body 12 tend to flow outward, forming a smoother
crimple 20.
Different plunger body diameters will, of course require separate dies having
the appropriate
major radius for the work piece.
[0086] The minor radius 208 is provided for a similar reason--to allow the
stresses of
formation to flow outward along the work piece. A small fillet radius 210 is
provided on the
outside edges of the blade 204 to reduce stress riser occurrence, a phenomenon
well-understood
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in the machine arts. The operation of the press with the die 200 installed
proceeds in a slow,
controlled manner, after the work piece--the body 12 of the plunger--is
supported in a fixture or
vise (not shown) opposite the die 200. This procedure achieves the desired
crimp 21 into the
recess 44 of the retaining nut 40. The curvatures of the major 206, minor 208,
and fillet 210 radii,
besides reducing stresses in the metal also retard the formation of cracks,
both during
manufacturing and during use of the bypass plungers in the field, where the
plunger is subject to
hard impacts under some conditions.
[0087] FIG. 20 illustrates an alternate embodiment to FIG. 4, showing a
split bobbin clutch
assembly 140 for a bypass plunger as disposed within a valve cage. The clutch
assembly is held
in place between the retaining or end nut 40 and a partition nut 142, both of
which are locked in
position by the use of a crimple 20. The crimple 20 deforms the wall of the
end nut 40 and the
valve cage 16, so that an extended portion of the crimples 20--(same as the
crimp 21 shown in
FIGS. 3 and 4)--protrudes into a respective relieved portion 44 of the screw
threads of both the
retaining or end nut 40 and the partition nut 142. The crimple 20 thus
functions similar to a set
screw or a pin to prevent the loosening of the screw threads of the retaining
or end nut 40 and the
partition nut 142.
[0088] The valve dart 170, shown in FIG. 20 in the valve closed (valve
seated as in FIG. 4)
position within the valve cage 16, has the structure shown in FIG. 17 (for
clarity, the surface
profile 172 is not shown). The surface profile 172 of the valve stem 34
portion of the valve dart
170 is depicted in FIG. 18. The clutch bobbin halves 140A and 140B are held
against the stem 34
of the valve dart 170 by springs 144 (which could be canted-coil or
conventional coil springs)
that are installed in the grooves 146 formed into the circumference of the
bobbin halves 140A
and 140B. Note that, when the valve dart 170 is seated inside the valve cage
16, the opposite end
of the valve dart 170 is slightly retracted--e.g., no more than about 0.030
inch--within the end of
the retaining nut 40.
[0089] Returning to FIGS. 3 and 4, which depict the open and closed state
of the dart valves
within the valve cage, an alternate embodiment of the valve dart assembly is
depicted in FIGS.
21 and 22. The embodiments of FIGS. 3 and 4, and 21 and 22 illustrate dart
valves equipped
with the canted coil spring that functions as the clutch mechanism. The
alternate embodiment of
FIGS. 21 and 22 is preferred when the bypass plunger is used in downhole
environments where
sand is frequently suspended in the fluids being lifted to the surface, It is
preferred in this
alternate embodiment of the present disclosure to provide seals on either side
of the canted coil
spring to minimize the possibility for particles of sand to become lodged in
the coils of the
canted-coil spring, thereby reducing its effectiveness as a clutch mechanism.
The valve dart 232
within the valve cage 216 is shown in open and closed positions or states,
respectively, in FIGS.
21 and 22. Included in FIGS. 21 and 22 are first and second "slipper seals"
244, 246, each one
installed in respective circumferential grooves 252, 254 formed in the inside
bore of the retaining
or end nut 240. The slipper seals 244, 246 are disposed on either side of the
canted-coil spring
242 installed in its circumferential groove 250 formed in the end nut 240.
Like the canted coil
spring 242, the slipper seals 244, 246 surround the stein 234 of the valve
dart 232, thereby
forming a seal against sand or other types of particles becoming trapped
within the canted coil
spring 242.
100901 The slipper seals 244, 246 may be formed from various ones of the
P 11-E
(polytetraflouroethylene) family of materials as 0-rings having a square (or
round) cross section.
Alternatives are filled Nylonnsluch as oil-filled Nyloin and equivalents Moly-
filled Nylon 6,
solid lubricant-filled NylorTm6. Other alternatives include semi-crystalline,
high temperature
engineering plastics based on the PEEK (polyetheretherketone) Of PAEK
(polyaiyletherketone)
polymers.
[00911 FIG. 23 illustrates an embodiment in accordance with the
disclosure with the valve
dart 32 in the open position and having at least one of the flow ports 18
closed or sealed by the
plug 19. Fluids and/or gases are blocked from flowing through the plugged flow
port 18, as
described in more detail below,
[0092] It is also within the scope or this disclosure that the plug 19
may be designed as a
sleeve that includes a passageway therethrough (not shown), rather than a
solid component. The
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plug sleeve including the passageway effectively reduces the inner diameter of
the flow port 18
and reduces an amount of fluids and/or gases that are allowed to flow through
the plugged flow
port 18. This modification permits further adjustment and control of the fall
speeds of the
plunger 10.
[00931 FIGS. 24 to 24C illustrate an embodiment in accordance with the
disclosure of a
plunger 300 that includes the open helix profile 72 and at least one plug 19
disposed in at least
one of the flow ports 18. The plunger 300 is shown, for example only, with
eight flow ports.
However, any number of flow ports 18, as appropriate for the implemented
environment, is
considered to be within the scope of this disclosure. Any or all of the flow
ports 18 may be
configured to be plugged or sealed by plug 19, and the plunger 300 is intended
to be employed
with any number, from zero to all, of the flow ports 18 each including a plug
19. The greater the
number of flow ports 18 that are sealed by plugs 19, the less fluids and/or
gases are permitted to
flow through the plunger 300, and thus, the slower the fall speed of the
plunger 300. The plugs
19 may be attached to the flow port 18 via an appropriate fastening means
determined by the
intended environment. Plug fasteners may include, as non-limiting examples,
threads (FIG.
24B), set screws, detents, welding, adhesives, etc., and/or the plug 19 may be
held in the flow
port 18 by interference fit.
[00941 The arrows in FIG. 24B illustrate, as an example only, flow of well
fluids and/or
gases through the valve cage 16 of plunger 300 with at least one of the flow
ports 18 closed by
plug 19. As illustrated, fluids and/or gases flow freely through the open flow
ports 18, but are
redirected around an outside of the plunger 300 where the flow ports 18 are
plugged. The plug
19 prevents flow though the sealed/plugged flow port 18, which inhibits or
slows descent of the
plunger 300 through the well tubing
[00951 FIGS. 25 and 25A illustrate an embodiment in accordance with the
disclosure of a
plunger 310 that includes central sealing rings 324 and is shown with eight
flow ports 18. At
least one of the flow ports 18 of plunger 310 is configured to receive the
plug 19 to adjust the fall
speed of the plunger 310.
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[00961 FIGS. 26 and 26A illustrate an embodiment in accordance with the
disclosure of a
plunger 320 that includes central sealing rings 324 and a flutes 372 located
between the valve
cage 16 and the sealing rings 26. Plunger 320 is shown with eight flow ports
18, and at least one
of the flow ports 18 of plunger 320 is configured to receive the plug 19 to
adjust the fall speed of
the plunger 320. Flutes 372 function similar to the helix 72, as described
above.
[0097] While exemplary embodiments of the disclosure have been shown, the
disclosure is
not limited and various changes and modifications may be made without
departing from the
spirit thereof. For example, canted-coil springs may be used to advantage in
split bobbin clutches
as described herein. Further, the profiles of the helical grooves and the flow
ports in the cage, the
surface finishes, the relative placements of the canted coil spring within the
retaining nut
attached to the cage, the form of the poppet valve--its stem, valve head, and
the corresponding
valve seat in the plunger body, the number of canted coil springs used within
the retaining nut or
in a split bobbin clutch assembly, the shape of the crimple and the die used
to form it, are some
illustrative examples of variations that fall within the scope of the
disclosure. Moreover, the
crimple feature is a technique that may be used in place of set screws, pins,
etc., to secure
threaded components from turning relative to each other. For example, end nuts
at either end of a
plunger body or a bumper spring or other similarly constructed device, may
employ a crimple as
described herein to useful advantage. The canted-coil spring used as a clutch
may also be used in
other structures for controlling sliding or reciprocating motion of a shaft
within the bore of a
corresponding structure of a device.
[00981 In regard to the use of a canted-coil spring in a clutchless
embodiment of a valve dart
assembly, several of the disclosed embodiments may use split bobbin clutch
assemblies in the
claimed combinations, wherein canted-coil springs or conventional coil springs
may be used to
hold the bobbin halves together around the stem of the valve dart, without
departing from the
concepts of the disclosure as disclosed herein.
[00991 Conditional language, such as, "can," "could," "might," or "may,"
unless specifically
stated otherwise, or otherwise understood within the context as used, is
generally intended to
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convey that certain implementations could, but do not necessarily, include
certain features and/or
elements while other implementations may not. Thus, such conditional language
generally is not
intended to imply that features and/or elements are in any way required for
one or more
implementations or that one or more implementations necessarily include these
features and/or
elements. It is also intended that, unless expressly stated, the features
and/or elements presented
in certain implementations may be used in combination with other features
and/or elements
disclosed herein.
[0100] The specification and annexed drawings disclose example embodiments
of the
present disclosure. Detail features shown in the drawings may be enlarged
herein to more clearly
depict the feature. Thus, several of the drawings are not precisely to scale.
Additionally, the
examples illustrate various features of the disclosure, but those of ordinary
skill in the art will
recognize that many further combinations and permutations of the disclosed
features are
possible. Accordingly, various modifications may be made to the disclosure
without departing
from the scope or spirit thereof. Further, other embodiments may be apparent
from the
specification and annexed drawings, and practice of disclosed embodiments as
presented herein.
Examples disclosed in the specification and the annexed drawings should be
considered, in all
respects, as illustrative and not limiting. Although specific terms are
employed herein, they are
used in a generic and descriptive sense only, and not intended to the limit
the present disclosure.
29
