Note: Descriptions are shown in the official language in which they were submitted.
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IN THE UNITED STATES PATENT AND TRADEMARK OFFICE
APPLICATION FOR PATENT
TITLE: ROTARY SEALING DEVICE
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The present invention relates generally to rotary sealing devices for
hydrodynamically
lubricated sealing between relatively rotating members. More specifically, the
present invention
concerns rotary cartridges for progressing cavity type artificial lift pumps,
wherein such cartridges
are provided with hydrodynamic sealing between relatively rotatable members,
such as between a
housing and a rotary sleeve or shaft and wherein the hydrodynamic seal or
seals serve as one or more
partitions between a contaminant environment and a lubricant. Even more
specifically, the present
invention concerns a contaminant pressure responsive, lubricant pressure
amplified rotary rod seal
cartridge for rotary shaft drive mechanisms, for establishing sealing at the
shaft to reservoir interface
and to prevent loss of process fluid from the oil and gas production
reservoir. Also, the present
invention concerns a rod seal cartridge for progressing cavity artificial lift
pumps or inj ection pumps
which contain a lubricant composition for lubrication of seals and wherein the
supply of lubricant
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has a pressure being amplified above and responsive to the pressure of the
contaminant environment
region to provide a pressure differential across the seal which enhances
resistance of the seals to
contaminant intrusion.
DESCRIPTION OF THE PRIOR ART
Since progressing cavity pumps were introduced, they have steadily gained
market share in
artificial lift service because of significant and well-known economic and
technical advantages over
the beam pump. The progressing cavity artificial lift pump is relatively
simple in principle concept,
and consists of a compact surface mounted rotary drive head unit (sometimes
called a "top drive")
and a submersed Moineau-type rotor-stator arrangement. The pump stator is
attached to the lower
end of the tubing, and the rotor is attached to the lower end of a rod string
typically consisting of
conventional lift pump sucker rods. The rod string and rotor are supported and
rotationally driven
by the surface mounted drive unit. Rotation of the rotor within the stator
produces a pumping action
to lift crude oil to the earth's surface. Progressing cavity pumps and top
drives are also used as
injection pumps for pumping high pressure fluids into wells.
The surface mounted drive unit is mounted to the well head, and provides a
flow tee to direct
the crude oil to a pipeline or suitable storage vessel. A conventional
stuffing box is located above
the flow tee to seal off the relatively rotating rod string drive shaft
assembly which penetrates
through the flow tee and stuffing box. The drive unit also incorporates a
sealed and lubricated
bearing housing assembly containing rotary bearings which axially and radially
support a
spindle/shaft which in turn supports the rod string. The spindle is
rotationally driven by a prime
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mover such as an electric or hydraulic motor. The bearing housing and stuffing
box are usually
axially separated by a conventional yoke arrangement which provides the
clearance needed to service
the stuffing box, and which also provides the space needed to temporarily
clamp-off the rod string
to support the rod string weight in the event that the bearing housing
assembly must be removed for
service. The yoke is sometimes called a "booth" within the top drive industry.
The surface mounted
drive unit also incorporates coupling means to rotationally drive the rod
string. In one popular
embodiment, the bearing guided rotary spindle of the bearing housing is hollow
and incorporates a
hexagonal internal shape which engages and rotationally drives a hexagonal
"slip shaft" which is in
turn threadedly attached to the rod string.
One significant remaining weakness of present day progressing cavity
artificial lift pumps
has been the conventional stuffing box arrangement provided to seal-off the
relatively rotating rod
string as it enters the yoke area. The stuffing box is filled with
conventional packing, which is a far
from optimum solution for sealing liquids containing abrasive particulate
matter, especially in
conjunction with significant differential pressure, as is the case in the
artificial lift pump application.
Artificial lift pump stuffing boxes require frequent re-greasing and
adjustment by means of a
conventional packing gland follower to compensate for wear and minimize crude
oil leakage. In
many stuffing box applications such as low pressure pumps for non-abrasive
liquids, lubrication
provided by leakage contributes significantly to the life of the packing, but
in the progressing cavity
artificial lift pump, the leakage contains abrasives which accelerate packing
wear, and cause
corresponding wear of the mating rod surface. Adjusting the packing ring gland
follower to control
leakage is a matter of judgment, and over-tightening can cause high
interfacial contact pressures
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which cause rapid packing failure, resulting in significant crude oil leakage.
The packing of the
present day progressing cavity artificial lift pump seals directly against the
rod string, however a
specially prepared rod called a "polished rod" or "polish rod" is provided.
The polished rod is
manufactured with better surface finish and dimensional tolerance than the
remainder of the rod
string, with a view towards providing a more suitable rotary sealing surface.
Unfortunately, however,
the surface of the polished rod quickly becomes damaged from handling and
environmental exposure
in ways that promote severe packing wear. For example, polished rod corrosion
scale, pitting, and
impact damage can be very detrimental to packing life. The drive heads of many
progressing cavity
artificial lift pumps permit significant dynamic run out of the polished rod,
often in conjunction with
severe rod string vibration. Such dynamic lateral shaft motion is difficult
for any rotary sealing
system to accommodate, and tends to wallow out the stufFng box packing and
produce unacceptable
crude oil leakage. Misalignment between the bearing housing and the stuffing
box can also be a
concern by creating uneven radial loading of the packing.
SUMMARY OF THE INVENTION
It is a principal feature of the present invention to provide a
hydrodynamically lubricated seal
cartridge for the rotary drive heads of rotary artificial lift pumps for wells
which utilizes well
pressure for developing a lubricant pressure which is amplified to a pressure
level above well
pressure, thus providing pressure differential across the hydrodynamic seals
to enhance resistance
of the seals to contaminant intrusion into the lubricant chamber of the seal
cartridge mechanism and
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to stimulate hydrodynamic wedging of lubricant into the dynamic sealing
interface of the seals with
the relatively rotatable surface of the rotary wear sleeve or other rotary
element;
It is also a feature of the present invention to provide a hydrodynamically
lubricated seal
cartridge for the rotary drive heads of rotary artificial lift pumps having
one or more pistons, which
may be external of the seal cartridge or incorporated within the structure of
the seal cartridge, which
piston or pistons function as a pressure transferring wall of a lubricant
chamber and are acted upon
by contaminant pressure, also referred to as pump pressure;
An objective of the present invention is to provide a rotary seal cartridge
for progressingv
cavity artificial lift pump drive heads which is readily adaptable to ~~ting-
pumps and which
provides longer maintenance intervals and service life, and accommodates
higher pressure, compared
to the conventional stuffing box sealing arrangements now used.
Another feature of the present invention is a bearing guided sleeve which
rotates in unison
with the polished rod, and provides a smooth, hardened, true running, abrasion
resistant running
surface for the rotary seals. By maintaining a constant, non-varying seal
extrusion gap, this true-
running sleeve preserves the life of the rotary seals by minimizing extrusion
damage. This sleeve
surrounds the polished rod, but runs true on it's own bearings and does not
follow the dynamic run
out and vibration induced lateral motion of the polished rod. The
exceptionally true running
characteristic of the sleeve is insured by (1) exploitation of the hydrostatic
force of the pressure of
the crude oil process fluid to preload one of the bearings in a way that
eliminates internal bearing
running clearance, (2) by spring loading of the opposite bearing in a way that
eliminates internal
bearing running clearance while accommodating differential thermal expansion,
and in a way that
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simultaneously prevents slippage of the inner race and thereby eliminates wear
and increased internal
clearance that would otherwise result from said slippage, and (3) by axial
clamping of the outer
bearing races so that the necessary installation clearance between the outer
race and the housing bore
cannot contribute to dynamic run out. The clamping arrangement also makes the
outer races immune
from spinning within the housing bore in the event that bearing torque
increases due to damage to
the bearing running surfaces.
Briefly, the various objects and features of the present invention are
realized through the
provision of a contaminant pressure responsive, lubricant pressure amplified
or modified rotary seal
cartridge for rotary well pumps and other rotary mechanisms. The lubricant
pressure amplified rotary
seal cartridge has a housing member having a passage therethrough and having
at least a portion of
said passage being subject to contaminant pressure. A rotary member, such as a
cartridge wear
sleeve is disposed for rotation within said passage and is supported for
rotation by a bearing
assembly, such as one or more rotary cone bearings which accommodate both side
loads and axial
thrust loads to which the wear sleeve may be subjected. A plurality of spaced
seals establish sealing
between the housing member and the rotary member and define at least one and
preferably two or
more lubricant chambers between the housing and the rotary member. At least
one and preferably
two or more cylinders are provided, each having a lubricant supply chamber
which is in fluid
communication with a respective lubricant chamber. A piston is moveable within
each of the
cylinders and has a first surface area exposed to lubricant within the
lubricant supply chamber and
a second surface area being different from the first surface area and being
exposed to contaminant
pressure.
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For purposes of the present invention, the term "contaminant pressure" is
employed to define
pressure from a well or other source which acts on the pistons in a direction
toward the lubricant
supply chambers of the cylinders. Contaminant pressure may be gas pressure
from a well, the
pressure of production fluid being pumped from a well or any pressurized
liquid or gaseous medium
being directed into the cylinders for the purpose of developing a lubricant
pressure in response
thereto. The term "ambient pressure" or "environment pressure" is defined as
the pressure of the
environment in which the seal cartridge mechanism is located.
The contaminant pressure acts on the second surface area and develops a
lubricant pressure
within the lubricant supply chamber which is different from contaminant
pressure. Preferably the
lubricant pressure is amplified above contaminant pressure so that the
lubricant pressure within each
of the lubricant chambers between the housing and rotary element establishes a
pressure differential
acting toward the lower pressure contaminant or environment. The higher
lubricant pressure serves
to hold the rotary seals straight, preventing skew-induced wear of the seals.
Moreover, since the
seals are preferably hydrodynamic seals, the higher lubricant pressure acts to
enhance the wedging
effect of the lubricant into the dynamic sealing interface between the seals
and the rotary member
by preventing process fluid pressure induced distortion of the hydrodynamic
geometry of the seal.
If desired, the cylinder and piston assemblies may be arranged to develop
pressure staging
between the respective lubricant chambers to provided for effective
hydrodynamic lubrication of
each of the seals and to accommodate high pressure conditions that would
otherwise cause failure
of many types of seals. As a further alternative the cylinder and their
respective chamber
communication with the lubricant chamber or chambers between the rotary member
and the housing
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and their respective communication with contaminant pressure may be arranged
to develop lubricant
pressure which is lower than contaminant pressure responsive to contaminant
pressure acting on the
pistons of the cylinders. Lubricant pressure may be staged by appropriate
arrangement of the
contaminant pressure responsive cylinder and piston assemblies to achieve
lubricant pressure in one
or more lubricant chamber which is higher than contaminant pressure and by
achieving lubricant
pressure in one or more lubricant chambers which is lower than contaminant
pressure.
BRIEF DESCRIPTION OF THE DRAWINGS
So that the manner in which the above recited features, advantages and objects
of the present
invention are attained and can be understood in detail, a more particular
description of the invention,
briefly summarized above, may be had by reference to the preferred embodiment
thereof which is
illustrated in the appended drawings, which drawings are incorporated as a
part hereof.
It is to be noted however, that the appended drawings illustrate only a
typical embodiment
of this invention and are therefore not to be considered limiting of its
scope, for the invention may
admit to other equally effective embodiments.
In the Drawings:
FIG. 1 is a sectional view of a contaminant pressure responsive, lubricant
pressure amplified
rotary rod seal cartridge constructed in accordance with the principles of the
present invention and
showing use of the housing member of the rod seal cartridge as a structural
element of the top drive
assembly that supports the yoke and the bearing housing assembly;
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FIG. 2 is a partial sectional view of an alternative embodiment of the present
invention
employing a mounting flange that is integral with the housing member and
adapted for bolted
connection to pumped fluid flow control equipment;
FIG. 3 is a partial sectional view of another of another alternative
embodiment of the present
invention, showing a contaminant pressure responsive, lubricant pressure
amplified rotary rod seal
cartridge employing a threaded pin connection for mounting of the housing
member to a flow tee
or other pumped fluid flow control equipment;
FIG. 4 is a sectional view of a contaminant pressure responsive, lubricant
pressure amplified
rotary rod seal cartridge representing a further alternative embodiment of the
present invention where
the cartridge can be retrofit to existing top drive units by the use of
adapters;
FIG. 5 is a sectional view of a contaminant pressure responsive, lubricant
pressure amplified
rotary rod seal cartridge representing a further alternative embodiment of the
present invention and
showing lubricant pressure amplifying cylinders being separate from the
cartridge housing and
supported by a common support base;
FIG. 6 is a sectional view of a contaminant pressure responsive, lubricant
pressure amplified
rotary rod seal cartridge representing another alternative embodiment of the
present invention and
showing pressure staging of the lubricant being supplied under pressure to the
bearing chamber and
the lubricant chamber between the hydrodynamic seals;
FIG. 7 is a sectional view of a contaminant pressure responsive, lubricant
pressure amplified
rotary rod seal cartridge representing a further alternative embodiment of the
present invention and
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showing a rotary wear sleeve being secured in non-rotational relation with a
rotary driven polished
rod by means of a collet type seal retainer and clamp;
FIG. 7A is a partial sectional view of a rod seal cartridge representing a
further alternative
embodiment of the present invention and showing a rotary wear sleeve being
secured in non-
rotational relation with a rotary driven polished rod by means of a collet
type seal retainer and clamp;
FIG. 8 is a sectional view of a contaminant pressure responsive, lubricant
pressure amplified
rotary rod seal cartridge representing another alternative embodiment of the
present invention and
showing hydrodynamic seals having direct sealing engagement with a rotary
driven polished rod and
with rotary stabilization of the polished rod by internal bearing surfaces of
the cartridge housing and
by one or more bushings seated within the housing;
FIG. 9 is a sectional view of a contaminant pressure responsive, lubricant
pressure amplified
rotary rod seal cartridge representing another alternative embodiment of the
present invention and
showing a housing structure having integral cylinders each having pistons
being responsive to
contaminant or pumped pressure and pressurizing lubricant with the cylinders
at the same or
different pressures;
FIG. 10 is a sectional view of an alternative embodiment of the present
invention showing
a seal cartridge housing having seals for sealing between the housing and a
polished rod and
illustrating communication of lubricant to the seals at an amplified lubricant
pressure determined by
contaminant pressure;
FIG. 11 is a sectional view similar to that of FIG. 10 and showing separation
of the lubricant
pressure amplification cylinder from a housing having the seals therein;
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FIG. 12 is a fragmentary sectional illustration showing a housing having seals
for sealing
between the housing and a polished rod similar to that of FIGS. 10 and 11 a
showing the seals as
being a stack of O-ring energized lip seals; and
FIG. 13 is a sectional view of a contaminant pressure responsive, lubricant
pressure
amplified rotary rod seal cartridge representing another further embodiment of
the present invention
and showing a cartridge housing having integrated annular pistons therein each
pressurizing
lubricant at the same or different lubricant pressures responsive to
contaminant pressure.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
Though the present invention is discussed herein particularly as it relates to
rotary drive
mechanisms for progressing cavity pumps, such discussion is not intended to
limit the spirit and
scope of the invention. The invention will also be found to have merit in any
apparatus where a
driven rotary shaft penetrates a vessel, reservoir, or other structure and is
in contact with or contains
a liquid so that a seal mechanism is required to contain the liquid and to
protect portions of support
means which may be in the form of a apparatus from contamination.
Referring now to the drawings and first to FIG. 1, a contaminant pressure
responsive,
lubricant pressure amplified rotary rod seal cartridge, such as is employed
for rotary well pumps,
such as rotary progressing cavity pumps, is shown generally at 10. The rotary
rod seal cartridge 10
has a bearing and seal carrying housing 12 which is adapted at its lower end
14 for threaded
assembly with a cartridge mounting base 16 which may be provided with a
mounting flange 18 for
bolted assembly of the cartridge 10 to a flow tee or to other wellhead
structure as desired. It is
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understood that the cartridge mounting base 16 and the mounting flange 18 may
vary widely in
design and construction, since the wellhead and fluid flow components may vary
widely from well
to well.
The bearing and seal housing 12 defines an internal bearing locator shoulder
20 which
provides for location of roller bearing races 22 and 23 which are received
within an internal
cylindrical bearing receptacle 24 of the housing 12. Roller bearing cones 26
and 28 of a wear sleeve
bearing assembly have respective rolling bearing engagement with tapered
roller bearing elements
30 and 32 and are disposed in bearing supporting engagement with the outer
cylindrical surface 34
of a wear sleeve 36. The wear sleeve is supported for rotation and guided
during rotation by the
wear sleeve bearing assembly and defines a central passage 37 within which is
received a polished
rod 190 which is rotatably driven by a rotary pump rod drive mechanism 182.
The term "polished
rod" is conventionally used to describe a rod which is engaged by seals for
the purpose of sealing
the rod with respect to another structure. The rod is "polished" because it is
prepared by finishing
or plating and finishing to define an extremely smooth wear resistant surface
for dynamic
engagement by one or more seals. With respect to the wear sleeve 36 the lower
portion of the roller
bearing cone 28 is supported and located by a support ring 38 which is in turn
supported by a retainer
element 40, such as a snap ring or split ring which is retained within an
annular externally opening
groove of the wear sleeve. The upper portion of the roller bearing assembly is
retained by a retainer
assembly 42 which is in turn supported by a retainer ring 44 which is also
received by an externally
opening groove of the wear sleeve.
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One of the tapered roller bearing cups 22 is retained seated against the
internal bearing
locator shoulder 20 by a depending generally cylindrical retainer extension of
a bearing and seal
retainer 48. The bearing and seal retainer 48 is retained in assembly with the
housing 12 by retainer
bolts 50 which extend through bolt openings of a retainer flange 52 of the
bearing and seal retainer
48. An annular seal member 54 retained within an annular internal seal groove
of the bearing and
seal Garner housing 12 is disposed in sealing engagement with an annular
external cylindrical surface
56 of the retainer extension 46, thus sealing the retainer 48 with respect to
the housing 12. The
bearing and seal retainer 48 defines an internal bore 58 which forms a part of
a centrally located
passage through the bearing and seal carrying housing 12.
The wear sleeve 36 defines a smooth, wear resistant outer sealing surface 60
which is
engaged by an annular hydrodynamic sealing element 62 carned within an
internally facing annular
seal groove of the bearing and seal retainer 48, with the annular dynamic
sealing surface of the seal
in sealing engagement with the cylindrical polished sealing surface 60. The
annular seal 62 is
arranged with a hydrodynamic geometry 64 thereof oriented for contact with
lubricant material
contained within an annular bearing lubricant chamber or reservoir 66 which is
defined between the
housing 12 and the cylindrical polished surface 60 of the wear sleeve 36.
At its lower end portion, the wear sleeve 36 defines an outer coating 68 also
composed of an
abrasive resistant material such as nickel based tungsten carbide or any one
of a number of other
suitable wear resistant materials which defines a cylindrical polished surface
70 which is engaged
by a pair of spaced annular hydrodynamic sealing elements 72 and 74 which are
carried within
spaced internally facing annular seal grooves of the bearing and seal retainer
housing 12, with the
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annular dynamic sealing surfaces of the seals in sealing engagement with the
cylindrical polished
surface 70. Preferably, the annular sealing elements 72 and 74 are
hydrodynamic seals embodying
the principles of the hydrodynamic seals of commonly assigned U.S. Patents
Nos. .5,230,520 and
5,738,358. The uppermost one of the spaced sealing elements 72 and 74 is
oriented with its axially
varying hydrodynamic geometry 64 in communication with the lubricant of the
annular lubricant
chamber 66. The lowermost one of the spaced sealing elements 72 and 74 is
oriented with its axially
varying hydrodynamic geometry in communication with the lubricant of an
annular lubricant supply
groove 76 which is an internal groove of the bearing and seal retainer housing
12 located between
the spaced sealing elements 72 and 74.
To supply the annular bearing lubricant chamber or reservoir 66 with lubricant
at a desired
lubricant pressure to be discussed in greater detail below, the bearing and
seal retainer housing 12
defines at least one and preferably a plurality of lubricant supply passages
78 which are disposed in
communication with an externally facing elongate, essentially vertically
oriented lubricant supply
groove or slot 80. The lubricant supply groove 80 is in fluid communication
with a lubricant supply
chamber 82 of a cylinder 84 via one or more lubricant supply passages 86 of
the cylinder structure.
For filling of the lubricant supply chamber with lubricant a suitable
lubricant fitting 87 is fixed to
the cylinder 84 and is in fluid communication with the lubricant chamber 82
thereof via a lubricant
fill passage 89. The cylinder 84 is fixed to the bearing and seal retainer
housing 12 by retainer bolts
shown at 88 and is sealed to the housing 12 by an obround seal 90 such as an O-
ring which
encompasses the lubricant supply groove 80 and thus confines the lubricant to
the lubricant supply
groove. A piston 92 is moveable within the cylinder 84 and is sealed with
respect to an internal
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cylindrical surface 94 of the cylinder by an annular high pressure seal 96. A
piston stem 98 extends
upwardly from the piston 92 through an opening 100 in the top wall 102 of the
cylinder and is sealed
with respect to the cylindrical surface defining the piston opening 100 by
another high pressure seal
104 which engages a cylindrical external surface 106 of the piston stem. In
order to achieve
mechanically induced hydraulically enhanced pressurization of the lubricant
within the lubricant
supply chamber 82 of the cylinder, in absence of any pump pressure acting on
the piston, a
compression spring 108 is positioned about the piston stem with its lower end
located against the
upper wall 102 of the cylinder. The upper end of the compression spring 108
bears against a spring
retainer 112 which is secured to the piston stern by a retainer ring 114 that
is received by an external
retainer groove of the piston stem.
The piston 92 defines a contaminant pressure responsive area 116 which is of
greater
dimension than a lubricant pressure responsive area 118, and to which
contaminant pressure, which
may also be referred to as pump pressure or well pressure, is communicated by
a contaminant
passage 120 of the bearing and seal retainer housing 12 with the well bore or
fluid flow passage 122
of the flow tee or other pumped fluid flow control assembly. The contaminant
passage 120 is sealed
with respect to the cylinder structure and the bearing and seal retainer
housing 12 by an obround
sealing element 125 which is oriented about the passage 120 and disposed in
sealing engagement
with the external surface of the cylinder. Thus the pressure of the pumped
well fluid or the gas
pressure of the well being pumped acts on the contaminant pressure responsive
area 116 of the piston
92 thus imparting an upward force to the piston which is added to the upward
force of the
compression spring 108. This upwardly directed force on the piston acts on the
lubricant within the
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lubricant supply chamber 82 through the lesser pressure responsive area 118 of
the piston and results
in elevation or amplification of lubricant pressure in excess of contaminant
pressure, the elevation
or amplification being determined by the pressure responsive area ratio of
piston surfaces 116 and
118. With the lubricant pressure in the annular lubricant reservoir 66 being
greater than contaminant
pressure acting within the pumped fluid flow passage 122, any differential
pressure existing across
any of the hydrodynamic seals will be in a direction from a lubricant chamber
toward the
contaminant or environment. This feature enhances the capability of the
hydrodynamic seals to
prevent intrusion of contaminant material into the lubricant supply either
from the pumped fluid or
from the environment within which the seal cartridge is located. The lubricant
pressure prevents the
hydrodynamic geometry of the seals from being distorted by the contaminant
pressure, and also
keeps the seals straight in their grooves to prevent the skew-related abrasive
wear that could
otherwise occur if the seals were not held straight. Also, due to the
lubricant pressure being higher
than the contaminant pressure, any increasing leakage that occurs past the
rotary seals as they
degrade will be lubricant leakage rather than abrasive laden contaminant
leakage.
Since it is possible that contaminant laden pumped fluid may enter the
cylinder via the
passage 120 the plug member 113 is provided with a tapered upper surface 123
which minimizes the
volume of contaminant fluid which may enter the cylinder. The tapered upper
surface 123 also
provides for drainage of any such fluid from the cylinder after the piston has
reached the limit of its
downward travel as contaminant fluid pressure is relieved.
In order to provide a supply of lubricant under similarly amplified pressure
to the annular
lubricant supply groove 76 to provide the hydrodynamic seals 72 and 74 with
lubrication, the bearing
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and seal retainer housing 12 defines at least one lubricant supply passage 124
which is in
communication with the annular lubricant supply groove 76 and with an external
elongate generally
vertically oriented fluid supply slot or groove 126. Lubricant pressure is
confined to the lubricant
supply groove 126 by an obround sealing element 128 which is retained in an
external seal groove
of the bearing and seal retainer housing 12. A lubricant supply passage 130
defined generally at the
intersection of the side wall 132 and top wall 134 of a second lubricant
pressure amplification
cylinder 136 chamber establishes lubricant supply communication with an
internal lubricant supply
chamber 138 of the cylinder 136. For filling the internal lubricant supply
chamber 138 with
lubricant, a lubricant fitting 137 is fixed to the cylinder 136 and is in
communication with the
internal lubricant supply chamber 138 via a lubricant fill passage 139. The
second pressure
amplification cylinder is also secured to the bearing and seal retainer
housing 12 by retainer bolts
146 or by any other suitable means for retention. A piston member 140 is
moveable within the
cylinder 136 and incorporates a high pressure sealing element 142 for
maintaining dynamic sealing
of the moveable piston member with an internal cylindrical surface 144 of the
cylinder. A piston
stem 148, which may be integral with the piston 140, extends through an
opening 150 in the top wall
134 of the cylinder and is sealed with respect to the top wall 134 by a high
pressure seal 152 which
is retained within an internal seal groove of the top wall and establishes
sealing engagement with an
outer cylindrical surface 154 of the piston stem.
In order to achieve mechanically actuated hydraulically enhanced
pressurization of the
lubricant within the lubricant supply chamber 138 of the cylinder 136, in
absence of any pump
pressure acting on the piston, a compression spring 156 is positioned about
the piston stem 148 with
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its lower end in engagement with the upper wall 134 of the cylinder. The upper
end of the
compression spring 156 bears against a spring retainer 160 which is secured to
the piston stem by
a retainer ring 162 received by an external retainer groove of the piston
stem.
It should be borne in mind that the ratio of pressure amplification of the
lubricant within the
respective lubricant supply chambers 82 and 138 of the cylinders 84 and 136
will be determined by
the pressure responsive area ratio of the contaminant pressure responsive and
lubricant exposed
surface areas of the respective pistons. This ratio may be changed by changing
the dimension of the
piston stems of the pistons. Thus, if a change in the amplification of
lubricant pressure is desired,
this can be accomplished simply by replacing one or both of the pressure
amplification cylinders
with cylinders having larger or smaller dimensioned piston stems.
The lower end of the cylinder 136 is closed by a plug member 164 which is
sealed to the
internal wall surface 166 of the cylinder by an annular sealing member 168
which is retained within
an external seal groove of the plug member. The plug member 164 is retained
within the cylinder
by an annular retainer ring 170 located within an internal retainer groove at
the bottom of the
cylinder. The piston 140 and the plug member, together with the wall structure
of the cylinder,
define a contaminant pressure chamber 171. Since, as discussed above, it is
possible that
contaminant laden pumped fluid may enter the cylinder via a contaminant
pressure supply passage
172 the plug member 164 is provided with a tapered upper surface 174 which
minimizes the volume
of contaminant fluid which may enter the cylinder. The tapered upper surface
174 also provides for
drainage of any such fluid from the cylinder after the piston has reached the
limit of its downward
travel as contaminant fluid pressure is relieved.
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At its upper portion the bearing and seal retainer housing 12 defines a
mounting flange 176
having openings through which the upper ends of the piston stems extend. A
yoke or housing
member 178, sometimes called a "booth", is secured to the mounting flange 176
by bolts 180 or by
any other suitable means for assembly. The yoke 178 provides support for a
bearing housing
assembly, gearbox or other rotary drive mechanism 182, which is secured to the
yoke by retainer
bolts 184. This arrangement provides an important safety benefit, in that the
lubricant fittings 87
and 137 are remote from the rotatable polished rod 190, which means that the
pump doesn't have
to be shut down to refill the lubricant cylinders 84 and 132. This allows the
unit to be safely
serviced in field conditions. This arrangement also provides an important cost
reduction benefit, in
that the housing 12 is integrated into the top drive assembly and serves as a
necessary structural
element to support the yoke 178 and bearing housing 182, thereby eliminating
the cost that would
otherwise be incurred by providing a separate structural member to support the
yoke 178 and bearing
housing 182.
At its upper end the wear sleeve 46 defines a drive flange 186 having drive
receptacles that
receive corresponding drive elements of a drive clamp 188 that is clamped to a
polished rod 190
being driven by the bearing housing assembly, gearbox or other rotary drive
mechanism 182. Thus,
the drive clamp being driven by the rotating polished rod imparts rotation to
the wear sleeve 36. The
upper end of the wear sleeve defines a stuffing box having seals such as O-
ring seals 183 therein for
sealing between the polished rod 190 and the wear sleeve. A seal retainer 185
retains the seals 183
within the stufFng box, and is used to install the seals 183 into the stuffing
box. The seal retainer
is threaded to the upper portion of the wear sleeve and may be rotated as
desired to establish proper
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mechanical compression of the seals 183 for proper sealing thereof with
respect to the polished rod.
During rotation of the wear sleeve, the wear sleeve is supported and
stabilized with respect to the
stationary housing 12 by the roller bearing assembly. A bushing 192, which may
be composed of
bronze or any other suitable bushing material, serves to stabilize the
polished rod 190 with respect
to the lower portion of the housing. The bushing 192 provides the additional
function of providing
a close clearance with the cylindrical surface of the polished rod 190 and
minimizes entry of
particulate into the pressure amplification cylinders. The minimal clearance
of the bushing with the
polished rod serves to exclude entry of large dimensioned particulate and
minimizes entry of
particulate of minimal dimension.
The piston stems 98 and 148 each define lubricant pressure relief recesses 241
and 242
respectively which are normally located above the respective circular stem
seals 104 and 152. When
the lubricant supply chambers of the respective cylinders 84 and 136 are
filled via lubricant fittings
87 and 137, the respective piston is moved downwardly against the force of its
compression spring.
When the selected lubricant supply chamber has been filled to its maximum
extent, the pressure
relief recess of the filled cylinder will interrupt the stem seal of the
cylinder and thus will vent a
small quantity of lubricant past the seal under spring force, until the spring
causes the pressure relief
recess to disengage from the stem seal of the. cylinder, thus permitting the
stem seal to reestablish
sealing with the piston stem. This feature provides the person filing the
lubricant supply chamber
with lubricant with a visual indication that the lubricant supply chamber is
full, and prevents over-
filling. If over-filling were permitted to occur, the thermal expansion of the
lubricant could create
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very high lubricant pressure, resulting in damage to the rotary seals 62, 72
and 74, and also
potentially yielding the various pressure-retaining structures, such as the
pistons, the cylinders, etc.
One advantage of the cylinder arrangement of the present invention is that the
piston position
provides a clear visual signal of seal performance; i.e. if a seal chamber has
failed, the piston moves
to the empty position. This means that one can merely drive by the well,
without even getting out
of one's vehicle, to ascertain seal chamber integrity. Piston position, and
cylinder pressure, 'can also
be monitored remotely by the use of appropriate position and/or pressure
sensors in order to remotely
monitor sealed chamber integrity. The dual-sealed chamber arrangement of FIG.
1, and of other
FIGs. Herein, provides for redundancy. In the event that any one seal fails,
the unit can continue to
run without leakage of the pumped fluid to the environment.
Referring now to FIG. 2, the partial sectional view illustrates a simplified
alternative
embodiment of the present invention, having like components which are referred
to by like reference
numerals as compared with the embodiment of FIG. 1. The housing structure 12
of the seal cartridge
of FIG. 2 defines a lower housing end 14 having an integral mounting flange
194 having a circle of
bolt openings 196 receiving mounting bolts 198 for securing the mounting
flange to the support
flange 200 of a flanged flow tee or other flow control structure 202 from
which fluid is pumped by
the rotary pump mechanism. A seal member 204 is employed for sealing between
the mounting
flange 194 and the support flange 200. Though not shown for purposes of
simplicity, the flanges
194 and 200 may also be provided with sealing surfaces for metal to metal
sealing as well as or in
lieu of various joint seals.
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In the alternative embodiment of FIG. 3 the housing structure 12 is shown at
its lower end
14 to be provided with a standard externally threaded pin connection 204 which
is received within
a conventional internally threaded box connection 206 of a tubular flow
control member 208 such
as a flow tee or flow conduit.
Refernng to FIG. 4, the alternative embodiment shown varies from that shown in
FIG. 1 only
in that the housing element 12 defines a lower end 14 having a circle of
internally threaded bolt
openings 210 at the lower mounting end 212 for mounting of the housing to a
suitable support
flange, adapter or other supporting structure, not shown. Thus, like
components are referred to by
like reference numerals. A sealing element 213 is employed to establish
sealing of the lower end
14 of the housing 12 to the support to which the housing is mounted. In this
embodiment, the
housing structure is not required to function additionally as a structural
member for support of a
drive head support yoke as in FIG. 1. The support flange or other support
structure in this case would
also provide structural support for a drive head support yoke, thus permitting
the housing to be
structurally designed only for support of the external cylinders 84 and 136.
This feature will permit
the housing to be manufactured at significantly less cost as compared to the
embodiment of FIG. 1,
and allow it to be retrofit to many different types of top drives by the use
of various adapters.
Referring now to FIG. 5, in comparison with FIG. l and other FIGS., like
components are
referred to by like reference numerals for purposes of simplicity and to
facilitate ready understanding
to the invention. A common mounting base 211 is provided to provide support
for the cartridge
housing 12 and to support the cylinders when the cylinders are not connected
in supported relation
with the housing. The mounting base 211 has a central opening 215 through
which the polished rod
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190 extends and defines an internally threaded mounting receptacle 214 having
a circular sealing
element 216 located within a circular seal groove. When a mounting adapter, a
threaded flow tee or
other flow control conduit is threaded into the mounting receptacle 214 the
circular sealing element
216 establishes sealing with the circular end surface thereof, thus sealing
the threaded flow tee or
other flow control conduit to the common mounting base 211. The common
mounting base 210 also
defines contaminant pressure communicating passages 120 and 172 which each
communicate with
the contaminant fluid pressure within the well bore or pumped fluid passage
122. The contaminant
pressure communicating passages 120 and 172 also communicate with cylinder
receptacles 218 and
220 which form portions of the contaminant fluid pressure receiving cylinder
chambers of the
cylinders 84 and 136, respectively. Mounting bolts 222 extend through openings
in the mounting
base 211 and are received by corresponding internally threaded bolt openings
of the lower end 14
of the housing member 12 and function to secure the housing member firmly to
the mounting base.
An annular seal element 224 establishes sealing at the interface of the lower
end of the housing
member with the mounting base 21 l and prevents leakage of contaminant
pressure from contaminant
or pumped fluid flow passage 122. Likewise, the cylinder 84 is mounted to the
common support
base 211 by mounting bolts 226 and is sealed with respect to the support base
by an annular sealing
element 228. Similarly, cylinder 136 is mounted to the base 211 by mounting
bolts 230 and is sealed
to the mounting base by an annular sealing element 232.
To establish lubricant communication from the lubricant supply chamber 82 with
the
lubricant chamber 66 to provide for lubrication of the bearing assemblies and
to provide lubricant
to the annular hydrodynamic sealing elements 62 and 72, a lubricant supply
conduit 234 is connected
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in communication with the lubricant supply passage 86 of the cylinder 84 and
is also connected in
communication with a lubricant supply passage 236 of the housing, which
generally corresponds in
construction and function to the lubricant supply passage 78 of FIG. 1. Thus,
as the piston 92 is
urged upwardly by the compression spring 108 or is forced upwardly by
contaminant pressure acting
on the pressure exposed surface area 116 of the piston, the lubricant within
the lubricant supply
chamber 82 of the cylinder 84 is pressurized and is conducted via the
lubricant supply conduit to the
lubricant chamber 66 between the housing 12 and the rotary wear sleeve 36. The
pressure of the
lubricant being communicated to the lubricant chamber 66 will be determined by
the spring force
of the compression spring and by the area differential defined by the
contaminant pressure and
lubricant exposed axeas of the piston 92. In the same manner, the lubricant
supply chamber 138 of
the cylinder 136 is communicated with the lubricant chamber 76 between the
hydrodynamic seals
72 and 74 by a lubricant supply conduit 238 which has one end thereof in
communication with the
lubricant supply passage 130 of the cylinder 136 and its opposite end in
communication with a
lubricant supply passage 240 essentially corresponding to the lubricant supply
passage 124 of FIGS.
l and 4. Thus, as the piston 140 is moved upwardly by the force of its
compression spring 156 or
the combined force of the compression spring and the force developed by
contaminant pressure
acting on the piston, the lubricant present within the lubricant supply
chamber 138 is subjected to
pressure by the piston force, thus supplying pressurized lubricant to the
annular lubricant supply
groove between the hydrodynamic seals 72 and 74.
The piston stems 98 and 148 each define lubricant pressure relief recesses 241
and 242
respectively which are normally located above the respective circular stem
seals 104 and 152. When
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lubricant is injected into the lubricant supply chambers of the respective
cylinders 84 and 136 via
lubricant fitting s 87 and 137, the respective piston is moved downwardly
against the force of its
compression spring. When the selected lubricant supply chamber has been filled
to its maximum
extent, the pressure relief recess of the filled cylinder will interrupt the
stem seal of the cylinder and
thus will vent a small quantity of lubricant past the seal under spring force,
until the spring causes
the pressure relief recess to disengage from the stem seal of the cylinder,
thus permitting the stem
seal to reestablish sealing with the piston stem. This feature provides the
person filing the lubricant
supply chamber with lubricant with a visual indication that the lubricant
supply chamber is full, and
prevents over-filling. If over-filling were permitted to occur, the thermal
expansion of the lubricant
could create very high lubricant pressure, resulting in damage to the rotary
seals 62, 72 and 74, and
also potentially yielding the various elements of the device, such as the
cylinders 84 and 36, the bolts
50, 222 226 and 230, the housing 12, the pistons 92 and 140, and the bearing
and seal retainer 48.
Referring now to FIG. 6, an alternative embodiment of the present invention is
shown which
is responsive to contaminant pressure and spring force and which accomplishes
pressure staging of
lubricant pressure to the isolated lubricant chambers of the rod seal
cartridge mechanism. Since the
seal cartridge mechanism is mounted to a common base structure 211 in similar
manner as discussed
above in connection with FIG. 5, like parts are referred to by like reference
numerals. The cylinder
136 is mounted to the common base 211 in the manner discussed above in
connection with FIG. 5
and the pressurized lubricant of the lubricant supply chamber 138 is
communicated to the annular
lubricant chamber defined partially by the annular groove 76 between the
hydrodynamic seals 72
and 74. Thus, the lubricant pressure being supplied to the lubricant chamber
from the lubricant
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supply chamber of the cylinder has a ratio of lubricant pressure with respect
to contaminant pressure
similar to that discussed above.
As shown at the right hand portion of FIG. 6, the lubricant supply chamber 82
of the cylinder
84 is in communication with the lubricant chamber 66 via passage 86, supply
conduit 234 and supply
passage 236. The piston 92 is inverted with respect to the embodiments of
FIGS. 1 and 5, thus the
piston stem 106 projects downwardly from the piston and through a piston
opening of the common
base structure 211 and is sealed with respect to the common base structure by
an annular high
pressure sealing assembly 246. Thus, the piston 92 defines a smaller
contaminant pressure exposed
area 248 of the piston as compared to the piston area 250 with which the
lubricant of the lubricant
supply chamber is in contact. This phenomenon causes the lubricant pressure of
the lubricant
chamber 66 to be less than the contaminant pressure to which the piston is
exposed and causes the
lubricant pressure within the lubricant chamber 76 to be greater than the
lubricant pressure of the
lubricant chamber 66 and greater than the contaminant pressure acting on both
of the pistons 92 and
140. This pressure staging arrangement is particularly useful in injection
pumps, where the pressure
of the fluid being pumped is relatively high, because the pressure is divided
among several seals.
FIG. 7 of the drawings is a sectional view similar to that of FIG. 1, but
showing the rotatable
wear sleeve being supported in non-rotational relation with the polished rod
by a collet type clamp
and seal retainer which achieves radial and axial positioning of the rotary
wear sleeve with respect
to the polished rod, thus causing the wear sleeve to rotate with precision
concentricity with respect
to the polished rod, and causing the wear sleeve to be positioned axially by
the polished rod, the
polished rod in turn being supported by the bearings of the bearing housing
assembly (not shown)
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as discussed previously. Like parts, in comparison with FIG. 1 are referred to
by like reference
numerals. The contaminant pressure responsive, lubricant pressure amplified
rotary rod seal cartridge
includes a seal carrier housing 246 which is adapted at its lower end with
threaded bolt openings
248 for receiving mounting bolts for securing the housing to a support
structure such as an adapter
or mounting flange. The housing 246 defines a generally cylindrical internal
bearing surface 58
which serves as a bearing or bushing for journaled engagement with a generally
cylindrical outer
surface 60 of a rotary wear sleeve 36. Thus, in essence, the generally
cylindrical internal bearing
surface 58 provides a simple, low cost bearing or bushing arrangement for the
rotary rod seal
cartridge mechanism. A bushing 192, which may be composed of bronze or any
other suitable
bushing material, serves to stabilize a polished rod 190 with respect to the
lower portion of the
housing. The bushing 192 provides the additional function of providing a close
clearance with the
cylindrical surface of the polished rod 190 and minimizes entry of particulate
into the pressure
amplification cylinders. The minimal clearance of the bushing with the
polished rod serves to
exclude entry of large dimensioned particulate and minimizes entry of
particulate of minimal
dimension. Annular seals 62, 72 and 74 are located within annular internal
seal grooves of the
housing 246 and establish sealing with the outer cylindrical surface 60 of the
wear sleeve.
Preferably, the annular seals 62, 72 and 74 are hydrodynamic seals for
hydrodynamically enhanced
lubrication of the sealing interface of the seals with the wear sleeve.
It is necessary that the wear sleeve be sealed to and rotate along with the
polished rod during
operation of the pump mechanism or other rotary actuated mechanism. The upper
end of the wear
sleeve defines a stuffing box having seals such as O-ring seals 183 therein
for sealing between the
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polished rod 190 and the wear sleeve. The upper end portion 250 of the wear
sleeve defines an
internal tapered cam surface 252 which is engaged by a correspondingly tapered
external surface 254
of a seal retainer element 256 in the form of a collet. A seal retainer cap
element 185 defines a top
wall 258 defining an opening through which the polished rod 190 extends and
defines an internally
threaded side wall 260 which is received in threaded engagement by an
externally threaded section
262 of the upper end portion 250 of the wear sleeve. As the seal retainer cap
is threaded onto the
externally threaded upper end of the wear sleeve the top wall of the seal
retainer cap forces the seal
retainer element 256 downwardly and causes the tapered surfaces 252 and 254 to
interact in cam-like
fashion to drive the seal retainer element radially inwardly into gripping
relation with the outer
surface of the polished rod 190 and thus fractionally securing the seal
retainer element and thus the
wear sleeve in non-rotatable, axially fixed relation with the polished rod.
Simultaneously, downward
movement of the seal retainer element may compresses the seal members 183 and
to enhance the
sealing capability thereof.
The partial sectional view of FIG. 7A discloses an alternative seal retainer
and collet clamp
mechanism as compared to that of FIG. 7. In this case, a collet type seal
retainer and clamp element
264 defines a tapered outer surface 266 which is engaged by an internally
tapered surface 268. As
the retainer cap 185 is rotated for tightening on the threaded section 262 of
the wear sleeve, the collet
clamp element 264 is driven radially inwardly by the reaction of tapered
surfaces 266 and 268 for
clamping engagement with the outer surface of the polished rod and thus
fractionally securing the
seal retainer element and thus the wear sleeve in non-rotatable, axially fixed
relation with the
polished rod. An annular stop flange 270 engages the upper end of the wear
sleeve and prevents
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over-compression of the annular sealing elements 183 as the retainer cap is
further threaded to
enhance the gripping effect of the collet type seal retainer and clamp 268.
The present invention is also applicable to situations where the use of a
rotary sleeve is not
desired or deemed appropriate. As shown in the sectional view of FIG. 8, an
alternative embodiment
is shown which incorporates many of the features shown and described above in
connection with
FIG. 4. Thus like components of these Figures are referred to by like
reference numerals. The
contaminant pressure responsive, lubricant pressure amplified rotary rod seal
cartridge 10 of FIG.
8 incorporates a bearing and seal Garner housing 272 having a circle of bolt
openings 210 at its lower
end 212 for mounting of the housing to a base or other support structure. A
circular sealing element
216 provides for sealing of the housing with respect to the base, adapter or
other support structure.
The housing defines an internal bore 58 which is dimensioned for bearing or
journaled engagement
by the external cylindrical surface of the polished rod 190. A bushing 276,
typically composed of
bronze or other suitable journal material, is retained within a bushing
receptacle 278, and has
journaled engagement with the outer cylindrical surface of the polished rod
and functions to provide
for additional stabilization of the polished rod as it is rotated within the
seal cartridge.
A plurality of annular seals 62, 72 and 74 are retained within internal seal
grooves of the
housing 272 with sealing surfaces thereof disposed in dynamic sealing
engagement with the outer
cylindrical surface of the polished rod 190. Preferably the seals 62, 72 and
74 are hydrodynamic
seals of the nature described above. To provide for lubrication of the bearing
interface between the
housing and the polished rod and between the seals 62 and 72, the lubricant
supply chamber 82 of
the lubricant pressure amplification or modification cylinder 84 is in
communication with the
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housing/polished rod interface 280 via passages 86, 80 and 78 and by annular
lubricant supply
groove 282. Thus, the lubricant being conducted to the housing/polished rod
interface 280 will be
at a lubricant pressure determined by the force of the compression spring 108
and the pressure of any
contaminant medium acting on the contaminant pressure responsive area 116 of
the piston 92.
The annular region between the seals 72 and 74 is supplied with pressurized
lubricant from
the lubricant supply chamber 138 of the cylinder 136 via passages 130, 126,
124 and 76 such as is
discussed in detail hereinabove. Thus, all of the seals 62, 72 and 74 are
efficiently supplied with
lubricant, with the pressure of the lubricant being determined by contaminant
pressure acting on the
respective pistons of the cylinders and being combined by the force of the
compression springs 108
and 156.
FIG. 9 is a sectional view of a further alternative embodiment of the present
invention, shown
generally at 10, having an integral housing and lubricant pressure
amplification system for the rotary
rod seal cartridge, thus simplifying manufacturing costs and resulting in a
rotary seal cartridge
mechanism that can be efficiently manufactured. The contaminant pressure
responsive, lubricant
pressure amplified rotary rod seal cartridge 10 is provided with a body
structure 12 having an upper
portion thereof constructed essentially as shown in FIGS. 4, 5 and 6. From the
lower portion of the
body structure 12 projects a pair of cylinders 84 and 136 which are preferably
integral with the body
structure as shown, but which may be assembled in any suitable fashion to the
body structure.
Preferably, the cylinders 84 and 136 are arranged in diametrically opposed
relation, but such
orientation is not required within the sprit and scope of the present
invention. Within the cylinder
84 a piston member 92 is moveable and is sealed with respect to an internal
cylindrical surface 94
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of the cylinder by an annular sealing element 96. A piston stem 98 projecting
from one side of the
piston 92 extends through a seal 104 which is carried by a removable cylinder
wall 284 which is
secured within the cylinder 84 by a retainer ring 286 received within an
internal retainer groove
defined within the end of the cylinder. The end wall 284 is sealed with
respect to the cylinder by
an annular sealing element 288.
The piston, cylinder and end wall collectively define a lubricant supply
chamber 82 which
is supplied with lubricant via a lubricant supply fitting 87 and passage 89.
The piston stem 98
defines an external tapered pressure relief recess shoulder 290 which normally
is located outwardly
of the annular seal 104 of the removable cylinder wall 284. In the event
sufficient lubricant is
injected into the lubricant supply chamber 82 to drive the piston 92 beyond
its desired limit of travel,
the tapered pressure relief recess shoulder 290 will move into the annular
seal 104, thereby breaking
its seal with the piston stem and permitting leakage of lubricant to occur.
Additionally, the lubricant
venting feature is important to prevent damage to the seal cartridge mechanism
in the event a
condition of thermal expansion of the lubricant should occur. As the lubricant
is heated, either by
changes in ambient temperature or by seal friction induced heat build-up
during rotary pump
operation, the thermally expanding lubricant will drive the piston in a
direction toward the
contaminant. At the point of maximum allowable travel of the piston the
tapered pressure relief
shoulder with move to venting position with respect to the stem seal of the
piston and cylinder
assembly thus venting excessive lubricant pressure from the cylinder.
Immediately upon venting,
the piston stem will again be moved by the spring 108 to its sealed position
with respect to the stem
seal. This lubricant venting feature provides a visual indication that the
cylinder is completely filled
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with lubricant and also minimizes the potential for damaging internal
components of the cylinder
or seal cartridge by over-filling and lubricant thermal expansion. For
example, if seal 72 is a
hydrodynamic seal, the hydrodynamic pumping action thereof could potentially
over-fill lubricant
supply chamber 138 in the absence of the lubricant venting pressure relief 297
of piston 140. The
tapered or chamfered pressure relief shoulder also serves a guiding function
to guide the piston stem
through the cylinder top wall seals during assembly of the pistons with the
cylinders. For supplying
pressurized lubricant from the lubricant supply chamber 82 of the cylinder 84,
a lubricant supply
passage 86, extending through a structural member 292 is in communication with
the lubricant
chamber 66 within which the roller bearing assemblies are contained. Thus, the
roller bearing
assemblies are efficiently lubricated during rotation of the wear sleeve. The
pressurized lubricant
within the lubricant chamber 66 also furnishes the annular sealing elements 62
and 72 with lubricant.
Preferably, seals 66, 72 and 74 are hydrodynamic seals so that movement of the
lubricant during
rotation of the wear sleeve 36 develops hydrodynamic wedging of lubricant into
the dynamic sealing
interface between the seals and the relatively rotatable surfaces of the
rotary wear sleeve.
The opposite cylinder 136 is also provided with a removable cylinder wall 294
which is
secured within the end of the cylinder by a retainer ring 296 or other
suitable method, such as a circle
of threaded fasteners, and is sealed with respect to the cylinder by a seal
ring 298. A lubricant
supply passage 130 extends through another structural element 300 and
communicates the lubricant
supply chamber 138 of the cylinder with the annular lubricant supply groove 76
which forms a part
of a lubricant chamber between the housing and the rotary wear sleeve and
between the sealing
elements 72 and 74. The contaminant pressure present within the pumped fluid
or contaminant
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passage 122 acts simultaneously on the pistons 92 and 140 and thus
simultaneously develops
pressures within the respective lubricant supply chambers which is dependent
upon the differential
area ratio of the surface areas of the pistons which are exposed to
contaminant pressure and the
surface areas of the pistons which are in contact with the lubricant. Thus,
the lubricant pressures
being communicated to the respective lubricant chambers may be different if
desired. The integral
housing and cylinder arrangement shown in FIG. 9 is easily manufactured by
simple techniques,
such as casting and lathe turning. Mill work is minimized by this
construction, greatly reducing the
cost of the assembly.
Within the spirit and scope of the present invention, lubricant at a pressure
amplified by
contaminant pressure may be communicated directly to seals that establish
sealing between the
housing 12 and polished rod 190. With regard to FIG. 10, the removable
cylinder 132 is mounted
to the seal cartridge housing 12 by mounting bolts 146. The region within the
cylinder 132 below
the piston member 140 is in communication with the annular contaminant or
pumped pressure via
the passage 172 of the cartridge housing 12. In this case the chamber or
passage 172 is at pump or
well pressure via housing clearance with the polished rod 190 and the
clearance of the bushing 276
with the polished rod. Lubricant is communicated from the lubricant supply
chamber 138 of the
cylinder 132 by a lubricant supply passage 130 of the cylinder and by a
lubricant supply passage 86
which is in communication with a lubricant chamber 66 within which seals 72
are also located. If
desired, the seals 72 may be hydrodynamic seals such as indicated above, or
the seals may have any
other suitable geometry as desired. Centrally of the stack of seals 172 a
lantern ring 285 is located
to maintain the central seals of the seal stack in spaced relation so that the
pressurized lubricant is
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conducted essentially centrally of the seal stack. The seals 72 are retained
by a seal retainer 287
which is secured to the housing 12 by retainer bolts 289.
The embodiment of FIG. 11 differs from the embodiment of FIG. 10 in that the
cylinder 136
is separated from the cartridge housing 12 and the lubricant and contaminant
pressures are
communicated from the cylinder to the housing by means of supply conduits. The
lubricant supply
passage 130 from the lubricant supply chamber 138 and the lubricant supply
passage 86 of the
housing 12 are in communication with a lubricant supply conduit 291 for
conducting pressurized
lubricant to the lubricant chamber in which the seals 72 and located. A
contaminant or pumped fluid
supply conduit 293 is connected to the cylinder closure plug member 164 and is
in communication
with the contaminant pressure supply passage 172 to the cartridge housing 12
for communicating
contaminant or pumped fluid pressure from the well fluid or pumped fluid
passage 122 into the
contaminant pressure chamber 171 of the cylinder. The plug member 164 defines
a tapered surface
174 which tapers to the central opening 175 of the plug member, thus draining
contaminant fluid,
which may contain some solid components from the contaminant pressure chamber
171, thus
minimizing the 'contaminant material to which the seal 142 of the piston may
be subjected.
FIG. 12 basically discloses the housing 12, seal retainer 287 and polished rod
190 which
corresponds to FIGS. 10 and 11. A plurality of seals 77, which may be of any
suitable type such as
the O-ring energized lip seals shown, are positioned in stacked relation and
establish sealing between
the housing 12 and the polished rod 190. Centrally of the seal gland, where
the gland is intersected
by the lubricant supply passage 86, the seals are spaced, with the upper seals
being subjected to
upwardly directed force responsive to lubricant pressure and with the lower
group of seals of the seal
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stack being forced downwardly by lubricant pressure. As with the other
arrangements, any leakage
past the seals will be clean lubricant, rather than the potentially abrasive-
laden fluid from fluid
passage 122.
Referring now to FIG. 13 of the drawings is a sectional view showing a
contaminant pressure
responsive lubricated rotary rod seal cartridge generally at 10 having a
housing 302 having a bottom
wall 304 and a side wall 306. The bottom wall 304 is provided with threaded
bolt holes 30~ which
receive mounting bolts for mounting the housing to a support base, adapter or
any other suitable
support structure. A seal 310 is received within an annular seal groove of the
bottom wall 304 for
sealing the bottom wall to the support base and preventing leakage of
contaminant pressure. The
bottom wall 304 also defines a centrally oriented recess 312 which is in
communication with a
pumped fluid supply passage 314. The centrally oriented recess 312 also
defines a portion of a
centrally located wear sleeve passage 316 extending through the housing 302.
The housing structure 302 also defines an interior bearing and seal support
housing which
corresponds in structure and function with the housing 12 and is thus referred
to by the same
reference numeral. Other like components are also referred to by like
reference numerals. The
interior bearing and seal support housing 12 is integral with and projects
upwardly from the bottom
wall 304 and defines an internal bearing locator and support shoulder 20 which
provides for location
and support of roller bearing cup 22 of one or more roller bearing assemblies
located within an
internal cylindrical bearing receptacle. The bearing assemblies have inner
roller bearing cones 26
and a plurality of tapered roller members 30, but may take any other suitable
form within the spirit
and scope of the present invention. A rotary wear sleeve 36 is supported by
the bearings within the
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36
centrally located passage 314 and is retained in relation to the bearing
assemblies by support rings
38 and 42 and retainer rings 40 and 44. A retainer element 48 has threaded
assembly with the upper
externally threaded section 318 of the interior bearing and seal carrying
housing 12. The bearings
are retained seated against the internal bearing locator and support shoulder
20 by a depending
annular retainer extension 46 which may be integrated with, or separable from
retainer element 48.
An annular seal 62, which may be a hydrodynamically lubricated sealing element
is carried
with an annular seal groove of the retainer element 48 and is disposed in
sealing engagement with
the outer cylindrical polished surface 60 of the wear sleeve 36. Additional
annular sealing elements
72 and 74, which are also preferably hydrodynamic seals of the character
described above, are
located within spaced seal grooves of the housing 12 and are in sealing
engagement with the outer
cylindrical polished surface 60 of the wear sleeve 36 . The seals 62 and 72
cooperate with
the housing 12 and the wear sleeve to define an annular lubricant chamber 66
and seals 72 and 74
cooperate with the housing 12 and the wear sleeve and with an annular
lubricant supply groove 76
to define another annular lubricant chamber.
iVVithin the spirit and scope of the present invention it is desirable to
pressurize the lubricant
within the lubricant chambers in response to contaminant pressure. It is also
desirable to achieve
pressurization of the lubricant within the lubricant chambers in absence of
contaminant pressure to
ensure lubrication of the sealing interfaces of the various seals with the
relatively rotatable surface
of the wear sleeve or other rotary member, and to hold the seals in position
to prevent skew-related
wear and that would otherwise occur if the seals were not held in position by
lubricant pressure. The
housing structure defines a contaminant pressure passage 320 which is in
communication with an
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37
annular piston chamber 322 having a bottom wall 324 and a pair of spaced
facing cylindrical wall
surfaces 326 and 328. A pair of annular piston members 330 and 332 are
moveable within the
annular piston chamber and are urged in one axial direction by respective
compression springs 108
and 156. The compression springs act on the pistons to apply mechanical spring
force which
develops lubricant pressure within the respective lubricant chambers which
feeds lubricant to the
annular hydrodynamic seals 62, 72 and 74 and thus provides for efficient
abrasive exclusion of the
respective sealing interfaces in absence of contaminant pressure. Thus, as
operation of the rotary
pumping system of a well is initiated and before pumped fluid reaches the
wellhead for application
of significant contaminant pressure to the pistons, spring force enhanced
lubricant pressurization
continuously occurs and holds the seals in unskewed orientation, and thus
prevents excessive wear
of the seals.
The annular piston 330 has an annular seal 334 which is disposed in sealing
engagement with
the cylindrical internal surface 326 of the side wall 306 of the housing
structure. The annular piston
330 is shown at its maximum upward position, with an annular shoulder 336
being in stopped
engagement with a piston seal retainer element 338 having an annular seal 340
thereof being in
sealing engagement with a cylindrical extension 342 of the annular piston 330.
The retainer element
338 is secured to the side wall 306 of the housing 302 by a threaded
connection 331 and is sealed
with respect to the side wall by an annular sealing element 339.
Annular piston member 332 carries an external seal 350 which is in sealing
engagement with
a cylindrical sealing surface 352 of the piston 330, thus providing for a
sealed relationship between
the pistons 330 and 332 regardless of the positions thereof within the annular
piston chamber 322.
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The piston 332 is also provided with an annular seal 354 which is in sealing
engagement with the
outer cylindrical surface 328 of the housing 12. The annular piston 332 is
also shown in its
maximum upward position, with its aimular shoulder 358 in stopped engagement
with the bearing
and seal retainer element 48. A cylindrical extension 360 of the annular
piston 332 is in sealing
engagement with a circular seal 362 of the bearing and seal retainer 48.
For pressurization of lubricant within the lubricant chamber 66 within which
the bearings are
located, a lubricant supply passage 364 is drilled or otherwise formed in the
wall structure of the
housing element 12 and is in communication with the lubricant supply chamber
366 which is defined
between the piston 332 and the bearing and seal retainer 48. A lubricant
supply port 368 in the
depending annular bearing retainer 46 communicates the lubricant supply
passage with the lubricant
chamber 66. Thus, as the piston 332 is acted upon by contaminant pressure, the
piston applies
pressure developing force to the lubricant within the lubricant chamber 66 to
provide for lubrication
and pressurized positioning of the seals. In absence of contaminant pressure,
the compression spring
108 acting on the piston 332 develops sufficient force on the piston to ensure
the feed of pressurized
lubricant within the lubricant chamber to ensure lubrication and pressurized
positioning of the seals.
Seals that are used in applications with little or no differential pressure
can become locally
skewed due to the combined effects of compression and thermal expansion. If
seal skew is present,
rotation can cause environmental abrasives to impinge upon and abrade the
sealing lip, and
consequently abrade the shaft or other rotary element. The compression springs
of the various
embodiments set forth herein achieve mechanically induced hydraulic
pressurization of the lubricant
medium. This hydraulic pressure acts on the various seals and forces the seals
against their gland
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walls even when contaminant pressure is absent and thus eliminates any skew of
the seals. This
feature ensures minimal wear and extended service life of the seals.
For pressurization of lubricant within the annular lubricant chamber defined
between the
seals 72 and 74, the wall structure of the housing 12, the bottom wall 304 and
the side wall 306 is
drilled to form a lubricant supply passage 370 which is in communication with
the annular lubricant
groove 76 and with the lubricant supply chamber 372 between the piston 330 and
the piston seal
retainer element 338. Thus, as the piston 330 is subjected to upwardly
directed force imparted to
the piston by contaminant pressure or spring force or both, pressurized
lubricant is supplied to the
annular lubricant chamber between the seals 72 and 74, thus providing the
seals with efficient
lubrication at all times.
In view of the foregoing it is evident that the present invention is one well
adapted to attain
all of the objects and features hereinabove set forth, together with other
objects and features which
are inherent in the apparatus disclosed herein.
As will be readily apparent to those skilled in the art, the present invention
may easily be
produced in other specific forms without departing from its spirit or
essential characteristics. The
present embodiment is, therefore, to be considered as merely illustrative and
not restrictive, the scope
of the invention being indicated by the claims rather than the foregoing
description, and all changes
which come within the meaning and range of equivalence of the claims are
therefore intended to be
embraced therein.
