Note: Descriptions are shown in the official language in which they were submitted.
UNIBODY BYPASS PLUNGER WITH CENTRALIZED HELIX
AND CRIMPLE FEATURE
This application is a divisional application divided from Canadian Patent
Application
2,921,176 filed on February 19, 2016.
BACKGROUND OF THE INVENTION
1. Field of the Invention:
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.
2. Background of the Invention and Description of the Prior Art:
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 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.
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Date Recue/Date Received 2022-07-11
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
respectively the descent or
ascent of the plunger. 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.
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 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.
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
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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
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 formed 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.
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.
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Date Recue/Date Received 2022-07-11
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 forming a
clutch to retard the
motion of the poppet valve between open and closed positions.
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 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.
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Date Recue/Date Received 2022-07-11
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.
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.
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
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.
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
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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; and at least one
crimple to lock the retaining
nut to the valve cage.
In another embodiment there is provided a bypass plunger, comprising: a
monolithic
hollow plunger body including a body portion and a valve cage portion, the
valve cage portion
forming a first end of the monolithic plunger body; a dart valve disposed
within the valve cage
portion and having a valve head connected to a valve stem, the valve stem
extending out of the first
end; a retaining device configured to close the first end of the monolithic
plunger body and to
retain the dart valve within the valve cage, the retaining device having
threads; and one or more
crimple detents extending inwardly from a surface and acting on the threads to
permanently secure
the retaining device to the valve cage.
In another embodiment there is provided a bypass plunger, comprising: a one-
piece hollow
plunger body having first and second ends; a valve cage formed at the first
end of the hollow
plunger body, the valve cage having an open end; a dart valve comprising: a
valve stem having
first and second ends; and a valve head connected to the first end of the
valve stem, wherein the
dart valve is configured to be reciprocatingly disposed within the valve cage;
and a retaining
device installed in the open end of the valve cage thereby retaining the dart
valve within the valve
cage, wherein the valve cage further comprises one or more crimple detents,
and wherein the
retaining device include threads and is permanently secured to the open end of
the valve cage by
the one or more crimple detents pushing against the threads.
In another embodiment there is provided a bypass plunger, comprising: a
monolithic
hollow plunger body having at least one crimple detent configured to secure a
member to the
monolithic hollow plunger body, wherein the member is secured to the
monolithic hollow body by
the at least one crimple detent acting on a thread of the member.
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Date Recue/Date Received 2022-07-11
In another embodiment there is provided a method of manufacturing a bypass
plunger,
comprising: generating a monolithic hollow plunger body including a body
portion and a valve
cage portion, the valve cage portion forming a first end of the monolithic
plunger body; generating
a retaining device having threads; installing the retaining device to thereby
close the first end of the
monolithic plunger body; and deforming the valve cage to thereby generate one
or more crimple
detents that make contact with the retaining device, the one or more crimple
detents acting on the
threads to permanently secure the retaining device to the valve cage.
In another embodiment there is provided a bypass plunger, comprising: a one-
piece,
monolithic hollow plunger body extending from a first end to a second end and
including a body
portion, a fishing neck portion and a valve cage portion; the fishing neck
portion forming the first
end and the valve cage portion forming the second end of the monolithic hollow
plunger body; and
a dart valve reciprocatingly disposed within the valve cage portion and having
a valve head
connected to a valve stem; wherein the valve head includes a sealing face
located on an end of the
valve head that is opposite the valve stem; and wherein the sealing face is
configured to seat
against a valve seat of the valve cage portion.
In another embodiment there is provided a bypass plunger, comprising: a one-
piece,
monolithic hollow plunger body having a first end and a second end, the
monolithic hollow
plunger body including a body portion, a fishing neck portion and a valve cage
portion, the fishing
neck portion forming the first end and the valve cage portion forming the
second end of the
monolithic hollow plunger body, the valve cage portion including at least one
flow port through a
sidewall of the valve cage portion, and including an opening to an internal
bore within the valve
cage portion; and a dart valve disposed within the valve cage portion and
including a valve head
connected to a valve stem; wherein the valve cage portion is configured such
that the valve head is
inserted through the opening to be seated against a valve seat located at an
end of the valve cage
portion that is farther from the opening than the at least one flow port.
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In another embodiment there is provided a downhole tool for use in oil and gas
wells,
comprising: a cylindrical body configured to travel within tubing of the oil
and gas well, the
cylindrical body including an internal bore having a threaded portion and an
outer surface having a
crimple detent; and a retaining device having an exterior surface with
external threads and a
relieved space within the external threads, wherein the retaining device is
secured to the cylindrical
body by the mating of the external threads of the retaining device with the
threaded portion of the
cylindrical tubing and the crimple detent of the outer surface of the
cylindrical body extending
inwardly into the relieved space of the retaining device.
In another embodiment there is provided a method of manufacturing a downhole
tool for
use in oil and gas wells, comprising: providing a cylindrical body configured
to travel within
tubing of the oil and gas well, the cylindrical tubing body including an
internal bore having a
threaded portion and an outer surface having a crimple detent; and providing a
retaining device
having an exterior surface with external threads and a relieved space within
the external threads,
securing the retaining device to the cylindrical body by the mating of the
external threads of the
retaining device with the threaded portion of the cylindrical tubing and the
crimple detent of the
outer surface of the cylindrical body extending inwardly into the relieved
space of the retaining
device.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 illustrates a side exploded view of one embodiment of a bypass
plunger according
to the present invention;
Figure 2 illustrates a cross section view of the embodiment of Figure 1 as
assembled;
Figure 3 illustrates a cross section detail view of the lower end of the
embodiment of Figure
2 with the valve shown in an open position;
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Date Recue/Date Received 2022-07-11
Figure 4 illustrates a cross section detail view of the lower end of the
embodiment of Figure
2 with the valve shown in a closed position;
Figure 5 illustrates a side cross section detail of an end (retaining) nut and
canted coil
spring for use with the embodiment of Figures 1 - 4;
Figure 6 illustrates an end cross section detail of the end (retaining) nut
and canted coil
spring depicted in Figure 5, for use with the embodiment of Figures 1 - 4;
Figure 7 illustrates an enlarged version of Figure 3;
Figure 8 illustrates an end cross section view of the embodiment depicted in
Figure 7;
Figure 9 illustrates a side view of a hollow body according to the present
invention having
a tight helix profile disposed in a central portion of the embodiment of
Figure 1;
Figure 10 illustrates a side view of a hollow body according to the present
invention having
an open helix profile disposed in a central portion of the embodiment of
Figure 1;
Figure 11 illustrates a first example of an alternative embodiment of a
plunger valve clutch
according to the present invention;
Figure 12 illustrates a second example of an alternative embodiment of a
plunger valve
clutch according to the present invention;
Figure 13 illustrates a third example of an alternative embodiment of a
plunger valve clutch
according to the present invention;
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Date Recue/Date Received 2022-07-11
Figure 14 illustrates an alternate embodiment of the bypass plunger of Figure
1 that uses a
split bobbin clutch;
Figure 15 illustrates a first example of an alternate embodiment of a plunger
valve dart
according to the present invention;
Figure 16 illustrates a second example of an alternate embodiment of a plunger
valve dart
according to the present invention;
Figure 17 illustrates a third example of an alternate embodiment of a plunger
valve dart
according to the present invention;
Figure 18 illustrates a detail view of the profile of a feature of the
embodiment of Figure
17;
Figure 19 illustrates a die for use in a press to form a crimple used in the
embodiments of
Figures 3, 4, 7, and 8;
Figure 20 illustrates an alternate embodiment to Figure 4, showing a split
bobbin clutch
assembly for a bypass plunger within a valve cage;
Figure 21 illustrates a cross section detail view of an alternate embodiment
of the lower end
of the embodiment of Figure 3 with the valve shown in an open position; and
Figure 22 illustrates a cross section detail view of an alternate embodiment
of the lower end
of the embodiment of Figure 4 with the valve shown in a closed position.
Date Recue/Date Received 2022-07-11
DETAILED DESCRIPTION OF THE INVENTION
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
combination of four essential features incorporated in a unibody bypass
plunger (aka unibody gas
lift plunger) as disclosed herein. The principle components of the unibody
bypass plunger
include 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. The novel features of the present
invention provide
reduction of manufacturing costs, and enhanced performance, durability, and
reliability,
advantages that result through substantially greater simplicity of design and
construction. The
features of this novel combination are described as follows.
One feature is a one piece or unitary hollow body and cage 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 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,
etc. to adjust the rate of descent. This unitary design minimizes the number
of parts and the
number of joints that must be formed and secured. One principle 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.
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)
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Date Recue/Date Received 2022-07-11
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.
The outer surface of the hollow plunger body of the present invention includes
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 the present invention, between these two
groups of concentric
rings, one group at each end of the hollow body, is a series of concentric
spiral (or helical) grooves
(not unlike the "valleys" of screw threads) 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.
The "clutch" of one embodiment of the present invention consists 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
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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 or retaining nut. Advantages of this
design include
elimination of the bobbin components and greater durability.
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 invention and are not to be
construed as limiting the
invention 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 invention. 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.
Figure 1 illustrates a side exploded view of one embodiment of an integrated,
unibody
bypass plunger according to the present invention. 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
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Date Recue/Date Received 2022-07-11
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 cage 16, the sealing rings 22, 24, and the
centralized helix 24 may
all be readily tailored during manufacture for a specific application. The
plunger body includes
the following defined 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. 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. 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
/ cage 16 unit.
The crimple 20 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.
Continuing with Figure 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
Figure 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 Figure 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)
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Date Recue/Date Received 2022-07-11
disposed into an internal circumferential groove 50 (See Figure 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.
Figure 2 illustrates a partial cross section view of the embodiment of Figure
1 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
Figures 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 Figure 2.
Figure 3 illustrates a cross section detail view of the lower (valve cage 16)
end of the
embodiment of the bypass plunger 10 shown in Figure 2 with the valve dart 32
in an open position.
Figure 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.
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
Figures 7 and 8. In the
claims or in the description of the present invention, which includes a one-
piece or "unitary"
hollow plunger body and valve cage, the crimple feature may be variously
described and
Date Recue/Date Received 2022-07-11
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.
Figure 4, which is similar to Figure 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 Figure 2 with 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.
Figure 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 Figures 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 12, 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.
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
16
Date Recue/Date Received 2022-07-11
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.
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.
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.
Continuing with Figure 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
17
Date Recue/Date Received 2022-07-11
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.
There are several alternate surface finishes to be illustrated and described
(See Figures 15
through 18) - combinations of recesses, grooves, undercuts, and surface
roughness - that may 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.
Figure 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 Figures 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.
Figure 7 illustrates an enlarged version of Figure 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 Figure 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.
18
Date Recue/Date Received 2022-07-11
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 Figure 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 Figure 8, which
illustrates an end cross section view of the embodiment depicted in Figure 7.
Figure 9 illustrates a side view of a hollow body bypass plunger 60 according
to the present
invention. The plunger of Figure 1 is depicted in Figure 9 with a groove
surrounding the central
portion of the body of the plunger and forming a tight helix profile 62.
Figure 10 illustrates a side
view of a hollow body bypass plunger 70 according to the present invention
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.
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
Figures 9 and 10
provides a means of varying the rate of spin imparted to the bypass plungers
60, 70. In the
example of Figure 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 Figure 10, a plurality of helical
grooves, typically three
19
Date Recue/Date Received 2022-07-11
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.
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,
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.
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.
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
Date Recue/Date Received 2022-07-11
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.
Figures 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
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 Figures 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
performance under downhole conditions.
The split bobbins of Figures 11, 12, and 13 differ from one another in the
location of
grooves for supporting the canted-coil spring embodiment. Figure 11 has the
grooves positioned
in each side face of the bobbin halves as shown. Figure 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. Figure 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
21
Date Recue/Date Received 2022-07-11
be constructed with more than one spring installed; thus Figure 13 is provided
here to illustrate the
concept.
It is possible to use a conventional coil spring in the embodiments depicted
in each Figure
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 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 substances.
Figure 11 illustrates a first example of an alternative embodiment of a
plunger valve clutch
according to the present invention. The clutch 80 is assembled from first 82
and second 84 halves
of a split bobbin assembly 86. A first canted-coil spring 88 installed in
groove 90, and a second
canted-coil spring 92 is installed in a similar groove 94 that are 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.
Figure 12 illustrates a second example of an alternative embodiment of a
plunger valve
clutch according to the present invention. The clutch 98 is assembled from
first 92 and second 94
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
Figure 12 because it is installed on the opposite face of the split bobbin
assembly 104. When
22
Date Recue/Date Received 2022-07-11
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.
Figure 13 illustrates a third example of an alternative embodiment of a
plunger valve clutch
according to the present invention. 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.
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.
Figure 14 illustrates an alternate embodiment of the present invention that is
similar to the
embodiment of Figure 1 except Figure 14 is shown with a split bobbin clutch
instead of the canted
coil spring 42 as shown in Figure 1. The clutch, an assembly of the split
bobbin halves 140A,
140B is shown without a garter spring for clarity. The split bobbins may be
encircled by one
garter (or canted coil) spring as shown or two garter springs in the manner of
Figures 11, 12, and
13.
A partition nut 142, for retaining the bobbin assembly between the
retaining or end nut 40 and
the partition nut 142, is shown adjacent to the clutch bobbins. The partition
nut 142 is provided to
ensure the clutch assembly 140A, 140B (and garter or canted coil spring)
remains in position
between the end nut 40 and the partition nut 142.
Figures 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
23
Date Recue/Date Received 2022-07-11
of alternative surface profiles for moderating the reciprocating motion of the
valve stem within the
clutch structure of the unibody bypass plunger 10.
Figure 15 illustrates a first example of an alternate embodiment of a plunger
valve dart 150
according to the present invention. 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 with the bypass
plunger. The first groove
152 provides a retention feature to position the canted coil spring 42 to
retain the valve dart150
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
Figure 5.
Figure 16 illustrates a second example of an alternate embodiment of a plunger
dart valve
according to the present invention. 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
24
Date Recue/Date Received 2022-07-11
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 Figure 5.
Figure 17 illustrates a third example of an alternate embodiment of a plunger
dart valve
according to the present invention. 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 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 Figure 18 to be
described. This dart
valve 170 is designed for use with the split bobbin clutch designs illustrated
in Figures 11, 12, and
13 described herein above.
Figure 18 illustrates a detail view of the profile of a feature of the
embodiment of Figure
16, wherein the alternating rib-and-groove profile is more clearly shown. The
surface profile 172
of the stem 34, shown in cross section in Figure 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.
Figure 19 illustrates one example of a die for use in a press to form a
crimple used in the
embodiments of Figures 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
Figures 3,4 and 7, 8.
Date Recue/Date Received 2022-07-11
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
body of the plunger 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.
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
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 (the vise is not shown,
as it is not part of the invention and is well known to persons skilled in the
art) 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.
Figure 20 illustrates an alternate embodiment to Figure 4, showing a split
bobbin clutch
assembly 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
Figures 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
26
Date Recue/Date Received 2022-07-11
screw or a pin to prevent the loosening of the screw threads of the retaining
or end nut 40 and the
partition nut 142.
The valve dart 170, shown in Figure 20 in the valve closed (valve seated as in
Figure 4)
position within the valve cage 16, has the structure shown in Figure 17. The
surface profile 172 of
the valve stem 34 portion of the valve dart 170 is depicted in Figure 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 slightly
retracted - e.g., no more
than about 0.030 inch - within the end of the retaining nut 40.
Returning to Figures 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 Figures 21
and 22. The embodiments of Figures 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
Figures 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 invention 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 Figures 21
and 22. Included in Figures 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 stem 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.
27
Date Recue/Date Received 2022-07-11
The slipper seals 244, 246 may be formed from various ones of the PTFE
(polytetraflouroethylene) family of materials as 0-rings having a square (or
round) cross section.
Alternatives are filled Nylon such as oil-filled Nylon 6 and equivalents Moly-
filled Nylon 6, solid
lubricant-filled Nylon 6. Other alternatives include semi-crystaline, high
temperature
engineering plastics based on the PEEK (polyetheretherketone) or PAEK
(polyaryletherketone)
polymers.
While the invention has been shown in only one of its forms, it is not thus
limited but is
susceptible to various changes and modifications 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 invention. 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.
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 invention as disclosed herein.
28
Date Recue/Date Received 2022-07-11
A final note about the drawings: detail features shown in the drawings may be
enlarged to
more clearly depict the feature. Thus, several of the drawings are not
precisely to scale.
EMBODIMENTS
Embodiment 1. 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 formed 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.
Embodiment 2. The bypass plunger of Embodiment 1, wherein the valve cage
comprises: a
tubular portion of the lower end of the bypass plunger having a plurality of
outward-angled ports in
its walls to enable fluid flow there-through during descent of the bypass
plunger; wherein the ports
are each disposed at an acute angle with the longitudinal axis of the valve
cage and are separated
by substantially equal angles around the wall of the valve cage.
Embodiment 3. The bypass plunger of Embodiment 1, wherein: the poppet valve is
disposed to move between a closed position in contact with the valve seat
formed in the hollow
body just above the valve cage portion of the hollow body and an open position
disposed away
from the valve seat; and the stem of the poppet valve comprises a smooth
surface ground to a
predetermined surface roughness.
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Date Recue/Date Received 2022-07-11
Embodiment 4. The bypass plunger of Embodiment 1, wherein: the retaining nut
is locked
from turning by 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.
Embodiment 5. The bypass plunger of Embodiment 1, wherein the at least one
helical
groove comprises: a continuous groove having a predetermined pitch, depth, and
profile according
to required spin and rate of descent of the bypass plunger through a well
tubing.
Embodiment 6. The bypass plunger of Embodiment 1, wherein the at least one
helical
groove comprises: a groove extending at least one full revolution around the
outer surface of the
hollow plunger body approximately midway between the first and second ends.
Embodiment 7. The bypass plunger of Embodiment 1, wherein the at least one
helical
groove comprises: a groove extending at least one and up to six full
revolutions around the outer
surface of the hollow plunger body approximately midway between the first and
second ends.
Embodiment 8. The bypass plunger of Embodiment 1, wherein the at least one
helical
groove comprises: first and second helical grooves separated by a fixed
spacing and disposed
around the outer surface of the hollow plunger body approximately midway
between the first and
second ends thereof.
Embodiment 9. The bypass plunger of Embodiment 4, wherein each crimple detent
comprises: a formed dent in the wall of the hollow body extending inward from
the surface of the
valve cage end of the hollow body into the external threads of the retaining
nut to lock the retaining
nut to the hollow body.
Date Recue/Date Received 2022-07-11
Embodiment 10. The bypass plunger of Embodiment 1, wherein: the retaining nut
is locked
from turning by first, second, and third crimple detents extending inward from
the surface of the
valve cage at the second end of hollow body and along equally-spaced radii of
the valve cage into
corresponding relieved spaces in the proximate external threads formed in the
outer surface of the
retaining nut.
Embodiment 11. The bypass plunger of Embodiment 1, wherein: the retaining nut
is locked
from turning by at least one crimple detent extending inward from the surface
of the valve cage at
the second end of hollow body and along a radii of the valve cage into a
corresponding relieved
space in the proximate external threads formed in the outer surface of the
retaining nut.
Embodiment 12. The bypass plunger of Embodiment 1, wherein the retaining nut
further
comprises: a canted coil spring disposed within a circumferential groove
formed within the
retaining nut thereby forming a clutch for retarding the motion of the poppet
valve.
Embodiment 13. The bypass plunger of Embodiment 12, wherein the retaining nut
further
comprises: a slipper seal disposed within a circumferential groove formed
within the retaining nut
on either side of the canted coil spring thereby forming a seal against sand
particles becoming
trapped within the canted coil spring.
Embodiment 14. 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; 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.
31
Date Recue/Date Received 2022-07-11
Embodiment 15. The bypass plunger of Embodiment 14, wherein the crimple
comprises: a
conical dent in the wall of the valve cage extending inward from the surface
of the valve cage into
the external threads of the retaining nut to lock the retaining nut to the
valve cage.
Embodiment 16. The bypass plunger of Embodiment 14, wherein: the retaining nut
is
locked from turning by the at least two crimples disposed along corresponding
radii of the valve
cage and extending inward and along the corresponding radii into relieved
spaces in the external
threads of the retaining nut.
Embodiment 17. The bypass plunger of Embodiment 16, wherein: the corresponding
radii
are equally-spaced around the longitudinal axis of the valve cage.
Embodiment 18. 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 forming a clutch to retard the
motion of the poppet
valve between open and closed positions.
32
Date Recue/Date Received 2022-07-11
Embodiment 19. The bypass plunger of Embodiment 18, wherein the continuous
helical
groove comprises: a helical groove extending at least one and up to six full
revolutions around the
outer surface of the hollow plunger body approximately midway between the
first and second
ends.
Embodiment 20. The bypass plunger of Embodiment 18, wherein the continuous
helical
groove comprises: a helical groove extending at least one and up to at least
twelve full revolutions
around the outer surface of the hollow plunger body approximately midway
between the first and
second ends of the hollow plunger body, wherein the width of the helical
grooves is
proportionately narrowed as the number of grooves is increased.
Embodiment 21. The bypass plunger of Embodiment 18, wherein the first and
second
crimple detents comprise: a formed dent in the wall of the valve cage
extending inward from the
surface of the valve cage into the external threads of the retaining nut to
lock the retaining nut to
the valve cage.
Embodiment 22. The bypass plunger of Embodiment 18, wherein the canted coil
spring
comprises: an elongated coil spring formed into a torus, the coils of the
spring aligned along the
axis of the torus wherein the coils of the coil spring are canted at an acute
angle relative to the axis
of the torus.
33
Date Recue/Date Received 2022-07-11
