U.S. patent application number 12/785192 was filed with the patent office on 2011-11-24 for wafer stuffing box.
This patent application is currently assigned to BLACKHAWK TECHNOLOGY COMPANY. Invention is credited to Mark Bertane, Michael Dominik, Steven R. Massie.
Application Number | 20110284204 12/785192 |
Document ID | / |
Family ID | 44971483 |
Filed Date | 2011-11-24 |
United States Patent
Application |
20110284204 |
Kind Code |
A1 |
Bertane; Mark ; et
al. |
November 24, 2011 |
WAFER STUFFING BOX
Abstract
A low-profile wafer stuffing box includes a plurality of
replaceable seals located within a single, unitary body. The body
includes a central bore with a plurality of internal channels, a
first internal channel located proximate a top surface of the body,
a second internal channel located proximate a bottom surface of the
body, and a third internal channel being located between the first
internal channel and the second internal channel. An internal fluid
corridor extends from the front wall through the stuffing box body
and into the third internal channel. The low-profile wafer stuffing
box may be used on reciprocating piston pumps.
Inventors: |
Bertane; Mark; (Glen Ellyn,
IL) ; Massie; Steven R.; (West Chicago, IL) ;
Dominik; Michael; (Homewood, IL) |
Assignee: |
BLACKHAWK TECHNOLOGY
COMPANY
Glen Ellyn
IL
|
Family ID: |
44971483 |
Appl. No.: |
12/785192 |
Filed: |
May 21, 2010 |
Current U.S.
Class: |
166/68 ;
166/84.1 |
Current CPC
Class: |
E21B 33/08 20130101;
E21B 43/127 20130101 |
Class at
Publication: |
166/68 ;
166/84.1 |
International
Class: |
E21B 33/02 20060101
E21B033/02; E21B 33/08 20060101 E21B033/08; E21B 43/00 20060101
E21B043/00 |
Claims
1. A reciprocating piston pump comprising: a riser pipe; a well
head attached to the riser pipe; a sucker rod disposed within the
riser pipe and extending through the well head, the sucker rod
having a piston attached thereto; an actuator having an actuator
rod operatively coupled to a ball screw, at least a portion of the
ball screw being disposed within the actuator rod; a motor
connected to the actuator and operatively coupled to the ball
screw, the motor rotating the ball screw within the actuator rod;
and a wafer stuffing box disposed between the well head and the
actuator, the wafer stuffing box including a stuffing box body and
a central bore running through the stuffing box body, the central
bore including an internal channel; wherein the actuator rod is
connected to the sucker rod by a connection fitting, the actuator
rod having an outer diameter that is greater than or equal to an
outer diameter of the connection fitting, and the central bore has
an inner diameter that is substantially equal to the outer diameter
of the actuator rod.
2. The reciprocating piston pump according to claim 1, further
comprising a plurality of inner channels within the central bore of
the wafer stuffing box.
3. The reciprocating piston pump according to claim 1, wherein one
side of the wafer stuffing box body comprises a recessed
channel.
4. The reciprocating piston pump according to claim 3, further
comprising a resilient seal disposed in the recessed channel.
5. The reciprocating piston pump according to claim 1, further
comprising a seal disposed in the inner channel.
6. The reciprocating piston pump according to claim 1, wherein the
wafer stuffing box includes a zerk fitting fluidly connected to an
internal corridor, the internal corridor being fluidly connected to
the internal channel for transferring a lubricant into the central
bore.
7. The reciprocating piston pump according to claim 1, comprising a
plurality of inner channels in the central bore.
8. A low-profile wafer stuffing box for a reciprocating piston
pump, the low-profile wafer stuffing box comprising: a stuffing box
body having a first side, a second side, a front wall, a rear wall,
and a pair of side walls; a central bore extending through the
stuffing box body from the first side to the second side; a
plurality of internal channels within the central bore, a first
seal disposed in a first internal channel and a second seal
disposed in a second internal channel, a third internal channel
being disposed between the first internal channel and the second
internal channel; an internal fluid corridor extending from the
front wall through the stuffing box body and into the third
internal channel.
9. The reciprocating piston pump according to claim 8, wherein the
one of the first and second seals comprises an inverted
channel.
10. The reciprocating piston pump according to claim 9, wherein the
inverted channel comprises two angled sidewalls connected by a
channel floor.
11. The reciprocating piston pump according to claim 10, wherein
the channel floor is oriented substantially perpendicular to a
longitudinal axis of the central bore.
12. The reciprocating piston pump according to claim 10, further
comprising a semi-rigid insert disposed in the inverted
channel.
13. The reciprocating piston pump according to claim 12, wherein
the semi-rigid insert comprises a segmented metal ring.
14. The reciprocating piston pump according to claim 9, wherein the
inverted channel comprises a pair of angled sidewalls that meet in
a center of the inverted channel.
15. The reciprocating piston pump according to claim 14, further
comprising an outer shelf connected to an angled surface, the outer
shelf being oriented substantially perpendicular to a longitudinal
axis of the wafer stuffing box.
16. The reciprocating piston pump according to claim 8, further
comprising a recessed channel on one side of the stuffing box
body.
17. The reciprocating piston pump according to claim 16, wherein
the first internal channel includes a rod wiper seal and the second
internal channel includes a scraper seal.
18. The wafer stuffing box of claim 16, further comprising a
resilient seal disposed within the recessed channel.
19. The wafer stuffing box of claim 18, further comprising a zerk
fitting disposed on the front wall, the zerk fitting being fluidly
connected to the internal fluid corridor.
20. A wafer stuffing box for a reciprocating piston pump, the wafer
stuffing box comprising: a body including a top side, a bottom
side, a front wall, a rear wall, and a pair of side walls; a
central opening extending through the body from the top side to the
bottom side; a plurality of internal channels disposed within the
central opening, a first internal channel being located near the
top side of the body, a second internal channel being located near
a bottom side of the body, and a third internal channel being
located between the first and second internal channels; an internal
corridor extending from the front side to the third internal
channel, the internal corridor being capable of transporting a
lubricant into the third internal channel; a rod scraper seal
disposed in the second internal channel, the rod scraper seal
including an inner cylindrical surface, an outer cylindrical
surface, and an inverted scraper channel on a bottom of the rod
scraper seal between the inner cylindrical surface and the outer
cylindrical surface; a semi-rigid insert disposed within the
inverted scraper channel; a rod wiper seal disposed in the first
internal channel, the rod wiper seal including an inner cylindrical
surface and an outer cylindrical surface, the inner cylindrical
surface being longer than the outer cylindrical surface along a
longitudinal axis of the rod wiper seal, an outer ledge connected
to a top end of the outer cylindrical surface, and an angled
surface connecting the outer ledge to the inner cylindrical
surface; an external channel disposed on the bottom side of the
body, the external channel surrounding the central opening; and a
resilient seal disposed within the external channel.
Description
FIELD OF THE DISCLOSURE
[0001] This invention relates generally to devices and methods for
pumping liquids and more particularly to stuffing box seals for
reciprocating piston pumps.
BACKGROUND OF THE INVENTION
[0002] There are a variety of techniques for pumping fluids from
underground reservoirs. Over a hundred years ago, general windmill
and hand pump systems were developed to access well water for
drinking and irrigation. The devices used top head drive piston
pumps and stand pipes for the fluid discharge. This basic
technology, albeit in more advanced forms, is in use today. Of
course today, pumping systems are used in a variety of applications
and come in a variety of other forms as well.
[0003] Many modern pumping techniques, for example, are called upon
to pump underground fluid in a liquid sealed manner. This is
particularly useful because in many applications, such as leachate
removal from a landfill, the fluids being pumped can be hazardous
to people and the environment. As a result, modern pumping systems
often include mechanisms that prevent leakage.
[0004] Modern reciprocating piston pumps used to pump wells
generally include a reciprocatable sucker rod having a piston at
one end, where the sucker rod and piston are disposed in a riser
pipe. As the sucker rod and piston reciprocate within the riser
pipe, liquid is pumped up the riser pipe by the piston and
ultimately to the ground for discharge. Actuators are used to move
the sucker rod within the riser pipe. The actuator may be attached
to a stand pipe surrounding the riser pipe. The actuator may
include an actuator rod that is moved within the actuator by
electrical, mechanical, or pneumatic means. The actuator rod is
connected to the sucker rod via a rod connector.
[0005] To prevent leakage, known pumping systems use a stuffing box
mounted near the top of the ground seal for the well. The stuffing
box forms a seal between the sucker rod and the actuator housing to
prevent pumped fluid from spilling onto the ground or seeping into
the actuator via the actuator rod.
[0006] Stuffing box designs, however, can fail to give long enough
seal lifetimes. Seal failures occur too frequently, especially
where pumps are used to pump against substantial back pressure
(liquid head pressure) and where pumps are used to pump fluid with
substantial amounts of grit or other contaminants.
[0007] Many stuffing box designs suffer from short life times and
replacement problems. For example, stuffing boxes that use packing
gland materials for sealing are problematic because of the constant
need to readjust the packing material. In these devices, materials
like graphite impregnated twine (plumber's oakum) or slant split
rubber bo-rings are used as the packing material, screwed down in
the stuffing box by a packing gland nut to create a liquid tight
seal against the drive rod. The packing material has to be
compressed just right to form a tight seal. However, if the
material is too compacted, the material may squeeze against the
drive rod and cause stalling of the pumping system. If the packing
material is too loose, fluid leakage will occur.
[0008] Moreover, the reciprocating action of the sucker rod in the
riser pipe will wear on the packing material, unpacking the
material and necessitating replacement of the stuffing box assembly
or finding some way of re-packing the packing material into the
desired, operable range.
[0009] Furthermore, it is time consuming to change out many of the
current stuffing box designs. In order to change the stuffing box,
or the seals within the stuffing box, the actuator must be
disconnected from the well head and the actuator rod must be
disconnected from the sucker rod at the rod connector and the rod
connector must be removed from the actuator rod. Finally, the
stuffing box may be slid off of the actuator rod and replaced with
a new stuffing box, or the seals in the old stuffing box are
replaced with new seals. Assembly occurs in the reverse.
[0010] Due to these problems, previous attempts to extend the
service life of the stuffing boxes have been made. Most of these
attempts have involved adding more seals to the stuffing box. Some
stuffing boxes now include 4 or more seals. However, simply adding
more seals to the stuffing box has not significantly extended the
service life of most known stuffing boxes.
SUMMARY OF THE INVENTION
[0011] A low-profile wafer stuffing box includes a plurality of
replaceable seals located within a single, unitary body. The body
includes a central bore with a plurality of internal channels, a
first internal channel located proximate a top surface of the body,
a second internal channel located proximate a bottom surface of the
body, and a third internal channel being located between the first
internal channel and the second internal channel. An internal fluid
corridor extends from the front wall through the stuffing box body
and into the third internal channel.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a side sectional view of a piston pump constructed
in accordance with teachings in the disclosure;
[0013] FIG. 2 is a close up side sectional view of the actuator, a
wafer stuffing box, and the discharge tee of the piston pump of
FIG. 1;
[0014] FIG. 3 is a side exploded view of the actuator of the piston
pump of FIG. 1;
[0015] FIG. 4 is a bottom perspective view of the wafer stuffing
box of FIG. 2;
[0016] FIG. 5 is a top plan view of the wafer stuffing box of FIG.
2;
[0017] FIG. 6 is a side cross-sectional view of the wafer stuffing
box of FIG. 2;
[0018] FIG. 6A is a close up of an internal channel of the wafer
stuffing box of FIG. 6;
[0019] FIG. 7 is a cross-sectional view of the wafer stuffing box
of FIG. 6 including replaceable seals disposed in internal channels
of the wafer stuffing box;
[0020] FIG. 8 is a cross-sectional view of the wafer stuffing box
of FIG. 2 disposed on the actuator rod of the piston pump of FIG. 1
with the actuator rod being coupled to a sucker rod with a
compression rod connector;
[0021] FIG. 9A is a bottom plan view of one of the replaceable
seals of FIG. 7, in particular, a scraper seal;
[0022] FIG. 9B is a cross-sectional view of the scraper seal of
FIG. 9A;
[0023] FIG. 10 A is a top plan view of another one of the
replaceable seals of FIG. 7, in particular, a rod wiper seal;
and
[0024] FIG. 10B is a cross-sectional view of the rod wiper seal of
FIG. 10A.
DETAILED DESCRIPTION
[0025] FIG. 1 illustrates one example of a piston pump 100
constructed in accordance with the teachings of the disclosure. The
piston pump 100 includes a riser pipe 102 and a valve assembly 104
attached to one end of the riser pipe 102. The valve assembly 104
includes a piston 106 connected to a drive or sucker rod 108. The
sucker rod 108 may be made of fiberglass, metal, or any other
suitable material. The sucker rod 108 extends through a flow
chamber 110 in the riser pipe 102 and the sucker rod 108 is movable
in a reciprocating motion through the flow chamber 110 thereby
causing the piston 106 to also move in a reciprocating motion,
which pumps liquid in a direction from the valve assembly 104
towards a discharge tee 112. The discharge tee 112 may be connected
to a pipeline (not shown) for transportation of the liquid to a
treatment site or collection system.
[0026] A motor 114 is operatively connected to the sucker rod 108
by an actuator 116 having an actuator rod 120. Limit switches 118
may measure movement (e.g., count numbers of strokes) of the
actuator rod 120 as the motor 114 moves the actuator rod 120. The
limit switches 118 may send signals to a controller (not shown) as
the actuator rod 120 passes by the limit switches 118 so that the
controller knows the location of the actuator rod 120. The
controller sends signals to the motor 114 based on input from the
limit switches 118 and a programmed operational routine, thereby
controlling the frequency and direction that the motor 114 moves
the actuator rod 120, and thus the sucker rod 108 and piston 106.
The actuator rod 120 and the sucker rod 108 may be attached to one
another with a connection fitting 121 (FIG. 2). The motor 114 may
be a variable speed motor to move the actuator at different speeds
and/or frequencies. The motor 114 may be electrically or
pneumatically actuated.
[0027] A yoke 124 (FIG. 2) connects the actuator 116 to the
discharge tee 112, which is connected to a well head 122. The yoke
124 may include a top plate 126 and a bottom plate 128 separated by
one or more pillars 130. The pillars 130 keep the top and bottom
plates 126, 128 separated, thereby forming a space 132 that
accommodates a wafer stuffing box 134. The space 132 is large
enough to accommodate a plurality of stacked wafer stuffing boxes
if desired. The wafer stuffing box 134 seals fluid within the flow
corridor 110 from the inside of the actuator 116. The wafer
stuffing box 134 may include one or more seals (as set forth
hereinafter) that scrape fluid off of, or otherwise seal fluid
from, the actuator rod 120 before the fluid can enter into the
actuator housing 136, thereby protecting internal components of the
actuator 116 from any harmful characteristics of the fluid.
[0028] FIG. 3 illustrates a fragmented view of the actuator 116.
The actuator housing 136 is located between a motor coupling 138
and a bottom plate 140. The bottom plate 140, in turn, is coupled
to the yoke 124 (FIG. 2). A bearing housing 142 including a zerk
fitting 144 is located near the top of the actuator housing 136,
proximate the motor coupling 138. The zerk fitting 144 forms a
sealable passage for lubrication of a thrust bearing 145. The motor
coupling 138, bearing housing 142, actuator housing 136, and bottom
plate 140 may be attached to one another via virtually any means of
attachment, such as, for example, fasteners 146, welding, adhesive,
etc. Inner components of the actuator 116 include a coupling device
148 comprising a coupling sleeve 150, a top shear coupling 152a and
a bottom shear coupling 152b. The coupling device 148 connects a
ball screw 154 to the motor 114 so that the ball screw 154 rotates
as the motor 114 turns. The shear couplings 152a, 152b provide
safety protection for the actuator in that the shear couplings
152a, 152b are designed to fail before the motor 114 or actuator
rod 120 should the sucker rod 108 or actuator rod 120 become stuck.
A ball screw nut 156 rides longitudinally along the ball screw 154
as the ball screw 154 rotates. The ball screw nut 156 is threadedly
connected to the ball screw 154. The ball screw nut 156 is attached
to an anti-rotation block 158, which prevents the actuator rod 120
from rotating with the ball screw 154. Instead, the rotation of the
ball screw 154 is transformed into linear motion via the ball screw
nut 156 and the anti-rotation block 158 so that the actuator rod
120 reciprocates longitudinally within the actuator 116 as the ball
screw 154 rotates.
[0029] FIG. 4 illustrates one embodiment of a wafer stuffing box
134 constructed in accordance with the teachings of the disclosure.
The wafer stuffing box 134 includes a body forming a rectangular
box shape in this embodiment. However, other shapes are possible,
such as, for example, cylindrical (having any cross-sectional
shape, such as, circular, oval, square, rectangular, polygonal,
etc), irregular, etc. The wafer stuffing box 134 body includes a
top surface 160, a bottom surface 162, a front wall 166, a rear
wall 168, and two side walls 164. The wafer stuffing box 134 also
includes one or more apertures 170 for receiving fasteners to
attach the wafer stuffing box 134 to the bottom plate 128 of the
yoke 124 (FIG. 2). A central opening 172 extends through the wafer
stuffing box 134 from the top surface 160 to the bottom surface
162. The central opening 172 is sized to receive the actuator rod
120 (FIG. 3). The central opening 172 includes one or more internal
channels 174 for receiving seal assemblies, or to provide
lubrication, as will be discussed further hereinafter. The bottom
surface 162 also may include a circular resilient seal 176. The
resilient seal 176 may take on virtually any shape, such as, for
example, circular, oval, rectangular, polygonal, etc. The resilient
seal 176 is seated within an external channel 178 formed in the
bottom surface 162 of the wafer stuffing box 134. The resilient
seal 176 forms a seal between adjacent wafer stuffing boxes 134
when a plurality of wafer stuffing boxes 134 are stacked within the
yoke 124.
[0030] FIGS. 5, 6, and 6A illustrate various parts of the wafer
stuffing box 134 of FIG. 4. In particular, FIG. 6 illustrates three
internal channels 174a, 174b, 174c. Other embodiments may include
more or less than three internal channels. In the illustrated
example, internal channels 174a and 174c are configured to secure a
seal (discussed further hereinafter) within the internal channels
174a, 174c respectively. Internal channel 174b is fluidly connected
to the zerk fitting 144, for example the internal channel 174b may
be connected to the zerk fitting 144 via an internal corridor 180
(FIG. 5). During operation, a maintenance technician can lubricate
the wafer stuffing box 134 by forcing a lubricant through the zerk
fitting 144, into the internal corridor 180, and into the internal
channel 174b. The lubricant may be held between the seals disposed
in internal channels 174a and 174c, thus enhancing the sealing
ability of the wafer stuffing box 134. Moreover, certain lubricants
may provide a protective coating to protect the actuator rod 120
against corrosion, impingement damage, or other harm. Keeping the
actuator rod 120 smooth and in good condition lengthens seal life
because rough actuator rods 120 have been observed to shorten seal
life by snagging and tearing the seals during actuation of the
actuator rod 120.
[0031] The bottom internal channel 174c may include an internal
shelf 182 and a chamfered portion 184 (FIG. 6A). The chamfered
portion 184 may serve to align a seal during insertion into the
bottom internal channel 174 and the internal shelf 182 helps to
secure the seal in the bottom internal channel 174. The chamfered
portion 184 may take on virtually any angle, the angle preferred to
be in the range of approximately 10.degree. and approximately
80.degree., and highly preferred to be in the range of
approximately 15.degree. and approximately 45.degree..
[0032] The wafer stuffing box 134 of FIGS. 4-6A is approximately
45/8 inches long, approximately 3 inches wide, and approximately 1
inch high. The central opening 172 has a larger diameter D1 (FIG.
7) proximate the top surface 160, and a smaller diameter D2 between
the top internal channel 174a and the bottom internal channel 174c.
In the embodiment of FIG. 7, the larger diameter is approximately
1.135 inches and the smaller diameter is approximately 1.001
inches. The larger diameter D1 allows a seal disposed in the top
internal channel 174a to flex and rotate somewhat during actuation
of the actuator rod 120 in order to wipe the actuator rod 120 clean
of any remaining fluid and/or lubricant. The smaller diameter D2
helps to contain lubricant within the internal channel 174b, while
simultaneously keeping the actuator rod 120 precisely centered
within the central opening 172. Of course, the dimensions herein
with respect to FIG. 4 are exemplary only. Those skilled in the art
may size the wafer stuffing box 134 as needed for any particular
operation.
[0033] The disclosed wafer stuffing box 134 advantageously results
in a relatively low-profile housing. In particular, in the example
disclosed in FIGS. 4-7, the low-profile body has a thickness that
is less than or equal to a diameter of the central opening 172. In
the particular example disclosed in FIGS. 4-7, each of the front,
rear, and side walls 166, 168, 164 has a height (as illustrated in
FIGS. 6 and 7) that is less than or equal to either diameter (D1 or
D2) of the central opening 172. As a result, the disclosed wafer
stuffing box 134 requires a smaller yoke 124 and/or a plurality of
the disclosed wafer stuffing boxes may be stacked one upon another
within a standard sized yoke 124.
[0034] An additional advantage of the disclosed wafer stuffing box
134 is that all of the replaceable seals (e.g., scraper seal 186
and rod wiper seal 188) are located within a single, unitary wafer
stuffing box body. This configuration results in fewer parts to
manufacture and stock. Thus, the disclosed wafer stuffing box 134
is less expensive to manufacture and less costly to stock as
inventory.
[0035] Moreover, the disclosed wafer stuffing box 134 has a sealing
ability that meets or exceeds the sealing ability of prior art
stuffing boxes while using fewer internal seals (e.g., the scraper
seal 186 and the rod wiper seal 188). As a result, manufacturing
costs are significantly reduced.
[0036] FIG. 7 illustrates a cross-sectional view of an example of
the wafer stuffing box 134 with a scraper seal 186 disposed in the
bottom internal channel 174c and a rod wiper seal 188 disposed in
the top inner channel 174a. The scraper seal 186 and the rod wiper
seal 188 are further described with respect to FIGS. 9 and 10.
[0037] The scraper seal 186 may be desirably formed of a
semi-stiff, yet flexible material such as, for example,
Teflon.RTM., plastic, Buna Nitrile, Viton.RTM., polyurethane, etc.
The scraper seal 186 has an inner diameter 186i and an outer
diameter 186o. A central bore forms an inner cylindrical surface
190. The scraper seal 186 also includes an outer cylindrical
surface 192. Between the inner cylindrical surface 190 and the
outer cylindrical surface 192 is an inverted scraper channel 194.
The inverted scraper channel 194 includes an angled inner surface
196 beginning at a bottom side of the scraper seal 186 and joining
the inner cylindrical surface 190 forming a sharp scraping point
191. The sharp scraping point 191 scrapes fluid off of the actuator
rod 120, funneling removed fluid into the inverted channel 194. An
outer angled surface 198 beginning at the bottom side of the
scraper seal 186 joins the outer cylindrical surface 192. The inner
and outer angled surfaces 196, 198 are joined by a channel floor
200 that in the embodiment of FIGS. 9A and 9B is substantially
perpendicular to the inner and outer cylindrical surfaces 190, 192.
To enhance the stiffness of the scraper seal 186, thereby
maintaining the sharp scraping point 191 in contact with the
actuator rod 120, and to prolong the useful life of the scraper
seal 186, a semi-rigid insert 202 is disposed within the scraper
channel 194. In one embodiment, the semi-rigid insert 202 may be a
segmented metal ring made of, for example, brass or any other metal
that is softer than chrome plated stainless steel. However, the
semi-rigid insert 202 may be formed from virtually any semi-rigid
material. The semi-rigid insert 202 especially stiffens the inner
cylindrical surface 190 to maintain a solid interface between the
scraper seal 186 and the actuator rod 120.
[0038] Like the scraper seal 186, the rod wiper seal 188 includes
an inner cylindrical surface 204 and an outer cylindrical surface
206. However, unlike the scraper seal 186, the inner cylindrical
surface 204 is longer than the outer cylindrical surface 206 along
a longitudinal axis of the rod wiper seal 188. An exterior of the
rod wiper seal 188 includes a ledge 208 and an angled surface 210
connecting the inner cylindrical surface 204 to the ledge 208. Like
the scraper seal 186, the rod wiper seal 188 includes an inverted
wiper channel 212 on a bottom side of the rod wiper seal 188.
However, unlike the scraper seal 186, the inverted wiper channel
212 does not have a channel floor. Rather, the inverted wiper
channel 212 includes an inner angled surface 214 and an outer
angled surface 216 that meet in a center of the inverted wiper
channel 212, thereby forming an inverted v-shape in the
cross-section. The rod wiper seal 188 may be formed of any
substantially resilient material such as, for example, Buna
Nitrile, Viton.RTM., Teflon.RTM., plastic, etc.
[0039] Returning now to FIG. 8, the wafer stuffing box 134 is
illustrated as being mounted on the actuator rod 120. Some
elements, such as the yoke 124 are omitted for clarity in this
Figure. The actuator rod 120 is attached to the sucker rod 108 via
the connection fitting 121. As the actuator rod 120 reciprocates
towards the motor (not shown, upward in FIG. 8), the scraper seal
186 scrapes fluid off of the external surface of the actuator rod
120 via the sharp scraping point 191. The actuator rod 120 may be
lubricated if any lubricant is disposed in inner channel 174b.
Finally, the rod wiper seal 188 wipes any lubricant and/or
remaining fluid off of the actuator rod 120 before that portion of
the actuator rod 120 moves into the actuator housing. Due to
friction between the actuator rod 120 and inner cylindrical surface
204 of the rod wiper seal 188, the rod wiper seal 188 may pivot
slightly, to allow a top of the rod wiper seal 188 to move radially
outward as the actuator rod 120 ascends. This movement may cause
the inverted channel 212 to expand slightly, forcing an edge of the
inverted channel 212 and the inner cylindrical surface 204 into
firm contact with the actuator rod 120. This movement angles the
edge between the inverted channel 212 and the inner cylindrical
surface 204 into the actuator rod 120, thereby enhancing wiping of
the actuator rod 120 and forcing any fluid or lubricant removed
from the actuator rod 120 into the inverted channel 212.
[0040] During removal of the wafer stuffing box 134, for
replacement of the seals, for example, the sucker rod 108 is
disconnected from the connection fitting 121. After the sucker rod
108 is disconnected, the wafer stuffing box 134 will slide off of
the end of the actuator rod 120, and over the connection fitting
121 because the outer diameter of the actuator rod 120 is greater
than, or equal to, the outer diameter of the connection fitting
121. Thus, the disclosed wafer stuffing box 134 is an improvement
over prior art stuffing boxes, which required removal of the
connection fitting 121 from the actuator rod 120 prior to removing
the stuffing box because the connection fitting was larger than the
diameter of the actuator rod 120.
[0041] Unlike known stuffing boxes that include packing gland
material, the disclosed wafer stuffing box 134 does not include the
packing gland material that is forced out of an opening in order to
seal the actuator rod. Thus, the disclosed wafer stuffing box 134
does not require a tightening mechanism to squeeze packing gland
material of an opening in the stuffing box body. As a result, the
disclosed wafer stuffing box 134 does not suffer from problems of
over-tightening (which induces unnecessary drag and friction on the
actuator rod causing premature failure of the stuffing box,
actuator rod, or motor), uneven tightening (which can cause
misalignment of the actuator rod), and constant readjustment due to
packing gland material loss. Moreover, the disclosed wafer stuffing
box 134 centers more easily than known stuffing boxes during
installation, thus reducing uneven side wear of the actuator rod or
replaceable seals.
[0042] Although certain piston pumps and stuffing boxes have been
described herein in accordance with the teachings of the present
disclosure, the scope of the appended claims is not limited
thereto. On the contrary, the claims cover all embodiments of the
teachings of this disclosure that fairly fall within the scope of
permissible equivalents.
* * * * *