Note: Descriptions are shown in the official language in which they were submitted.
~136667
This invention is related to a seal assembly, and
more particularly to a seal assembly which may be used with
downhole oil well hydraulic pumps to seal between the pump
body and a housing which contains or mounts the pump when it
is installed in the well.
T'nis is a division of copending Canadian Patent
Application Serial number 330,781, filed June 28, 1979.
Some pumps used in this oil well service are provided
with some type of seal around the pump body to seal ~ithin
- 10 portions of the pump housing. Typically these seals are
constructed with a metal ring to provide sufficient radial
strength and prevent their being dislodged from the pump body
while the pump is-installed in or removed from the well.
Because these prior art seal constructions include a metal rina,
the seal cannot be radially expanded and slipped over the pump
body for installation. This construction necessitates the pump
body being made in several separable sections to allow for
installation of these seals. This multiple section construction
complicates the manufacture of the pump body as well as requiring
additional seals within the pump.
.,~. ... .
According to the present invention there is provided
a seal assembly for sealin~g around a tubular member which is
mounted within an opening in a housing or the like. The assembly
includes a cross-sectional generally dovetail shaped groove
around the tubular member with one side of the groove being
dovetailed in the bottom portion only and having the outer
portion of the side inclined in a divergent relation from the
groove. An annular seal element is mounted within the aroove
and extends therefrom and includes an inner portion contacting
cg/ ~
: ; :
~136667
the bottom of the groove, ~n auter portion extends from the
groove, and an outer peripheral sealinq surface is provided
on the exterior of the seal element. The seal element has a
lip formed at one end portion thereof by a recess around the
outer perimeter thereof which undercuts a segment of the seal
ring at that end portion thereof. The lip is shaped so that
the fluid acting toward the end portion of the seal element
havin~ the lip will urge the lip outward into sealin~ engagement
with the housing.
One object of this invention is to provide a seal
assembly overcoming the aforementioned disadvantaqes o the
prior art devices.
Still an object of a specific embodiment of the
invention is to provide a seal assembly for a do~hole oil well
hydraulic pump which can be easily slipped over the pump body
and held in place by the shape of the groove around the body.
It is also an object of a specific embodiment of the
invention to provide a seal assembly for a hydraulic oil well
pump which can withstand repeated assembly and disassembly by
installing the pump body within the housing and removing it
from the housing-without damage to the seal element.
Various other objects, advantages, and features of
this invention will become apparent to those skilled in the
art from the following discussion, taken in conjunction with
the accompanying drawings, in which:
DESCRIPTION OF THE DRAWINGS
Fig. 1 is a cutaway pictorial elevation view of a
segment of well casing having a hydraulically actuated down-
hole pump housing and pump body mounted therein;
~- 2 -
cg/~V
.:
113f~667
Fig. 2 is a cross-sectional elevation view of a seq-
ment of a pump housing and a segment of a pump body having
the seal assembly of thls invention with the seal element
spaced from the entrance to the pump housing prior to instal-
lation;
Fig. 3 is a cross-sectional elevation viéw of a
segment of the pump housing and pump body shown in Fig. 2
with the seal assembly installed;
Fig. 4 is an enlarged cross-sectional elevation view
1~ of the seal element alone in a free position;
Fig. 5 is an enlarged cross-sectional elevation view
of a segment of the pump body having the groove and with the
seal element shown positioned therein in dashed lines; and
Fig. 6 is an enlarged cross-sectional elevation view
of a segment of the pump body and pump housing t~7ith the seal
ring mounted therein showing the seal element with fluid
pressure applied toward the seal from the upper portion of the
figure or the end of the seal havin~ the recess.
- 2a -
cg/~C~
'' ' " ' 1136667
The following is a discussion and description of
preferred specific embodiments of the seal assembly of this
invention, such being made with reference to the drawings,
whereupon the same reference numerals are used to indicate
the same or similar parts and/or structure. It is to be
understood that such description and discussion is not to
unduly limit the scope of the invention.
Detailed Description
Referring to Fig. 1, such shows a downhole oil well
10 hydraulically actuated pump and employing the seal assemblies
of this invention mounted within a segment of casing 10. The
~ pump consists of a pump housing 12 which is sealingly mounted
within casing 10 and is hollow on the interior thereof to
receive and mount the pump body 14 which contains the working
15 elements of the pump. Pump body 14 contains a pair of pis-
tons 16 which are secured to opposite ends of a pump rod 18.
Pump rod 18 extends through a reversing valve assembly 20
which controls the motion of the pistons 16. Fluid passage-
ways between pump body 14 and pump housing 12 are sealed by
20 a plurality of seal assemblies 22. The several seal assem-
blies 22 are a plurality of the seal assembly of this inven-
tion and provide seals at the points within the pump where
fluid under pressure i5 transmitted between pump housing 12
and pump body 14.
Fig. 2 shows a segment of pump housing 12 and a
segment of pump body 14 with seal assembly 22 around pump
body 14 in a spaced relation to the pump housing bore 24
where it will ultimately reside when installed. Displacement
of pump body 14 into its final resting position in pump hous-
30 ing 12 positions the seal assembly within the confines of
seal bore 24. Positioning seal assembly 22 at this location
rad;ally compresses the seal element 26 to produce a fluid
tight seal between pump body 14 and pump housing 12.
Fig. 4 shows seal element 26 in an enlarged cross-
35 sectional view with the seal element in its undeformed or
free state. Seal member 26 is constructed of a molded
elastomeric compound andformed in the shown shape. The
interior of seal element 2S has an inner peripheral surface
28 which is uniform in cross-section and substantially the
1~36667
--4--
same diameter as the bottom of the groove in which the seal
element will be mounted. The exterior of seal element 26 has
an outer peripheral surface 30 which is inclined relative to
inner peripheral surface 28. A recess at one end of seal
5 element 26 around the outer periphery thereof forms a lip 32.
Outer peripheral surface 30 is inclined or tapered so the
- portion of the seal element having lip 32 is at the greater
thickness portion of the seal element. Seal end surface 36
is inclined relative to inner peripheral surface 28 and ori-
10 ented to fit within the confines of the dovetail groovearound the valve body 14. Seal end surface 36 is smoothly
curved to join seal inner peripheral surface 28 as shown.
Seal end surface 40 is angularly oriented to cor-
respond with the internal shape of the dovetail groove in
15 valve body 14. Seal end surface 40 is smoothly curved to
join seal inner peripheral surface 28 as shown. Around the
outer peripheral portion of this end of seal element 26, the
recess which forms lip 32 includes an elongated side 42 sub-
stantially parallel to inner peripheral surface 28 and ex-
20 tending from end surface 40 toward the opposite end of theseal element. Elongated surface 42 joins a radially inner
end of a cross-sectionally S-shaped surface which connects
on its other end with outer peripheral surface 30. An inner
curved portion 44 of this S-shaped surface extends toward
25 seal element end 36 and the other curved portion 46 of this
S-shaped surface extends in the opposite direction thereby
forming lip 32. The S-shaped surface in its radially outer
portion forms a portion of lip 32 and its radially inner
portion forms an undercut of the material which comprises
- 3~ the lip. The radial thickness of this undercut can be ap-
proximately the same as the radial thickness of lip 32 in
its thickest portion as shown in the drawings. This propor-
tion will allow significant flexure of lip 32 and accomoda-
tion for radial compression of the seal element to insure
35 proper sealing.
Fig. 5 shows in an enlarged view the sealing ele-
ment groove in pump body 14. This groove is generally dove-
tailed in its cross-sectional shape and includes a bottom
surface which is parallel to the longitudinal axis of valve
' 1136667
-5-
body 14 and opposed sides, one of ~7hich extends to pump body
outer surface 48 in a uniform fashion and the other of which
extends to pump body outer surface 48 in a broken or two step
fashion. Referring to the lower portion of Fig. 5, this
shows the simplest groove side which includes a curved sur-
face 50 connecting grooYe ~ottom surface 47 to an inclined
groo~e side 52 that extends to pump body outer surface 48.
At the opposite side of the groove, another curved surface 54
connects groove bottom surface 47 with a short inclined
10 groove side 56 that terminates approximately at the mid-depth
of the groove. Inclined groove side 56 is oriented in the
opposite direction to incline groo~é side 52. Ano~her groove
end surface 58 is inclined in the opposite direction to sur-
face 56 and joins the radially outer end of groove side 56
15 and connects with pump body outer surface 48 in order to pro-
vide a relief in that end portion of the sealing element
groove which makes the dovetail feature in that side of the
groove approximately one half the depth of the dovetail
feature in the opposite side of the groove.
Fig. 5 shows seal element 26, in dashed lines,
positioned in the sealing element groove. Seal element 26 is
sized to fit within the confines of the dovetailed shaped
groove wherein seal end surfaces 36 and 40 rest adjacent to
groove sides 52 and 56 and inner peripheral seal surface 28
25 rests in adjacent to grooYe bottom surface 47. On the outerperiphery of seal element 26, outer peripheral surface 30
aligns with pump body outer surface 48 at the juncture of
groove inclined side surface 52 and seal end surface 36.
Because seal element 26 is thicker through the portion ha~ing
30 lip 32, that portion of the seal element extends radially
outward beyond the cylindrical plane or form defined by the
pump body outer surface 48 and that portion of the seal is
displaced upon installation of the pump body in pump housing
12.
Fig. 6 illustrates the seal element in a position
it assumes when pump body 14 is mounted within pump housing
12 and fluid pressure is applied to the seal element from
between the pump housing and pump body at the end of the seal
with lip 32. Seal outer peripheral surface 30 is in flush
,,,,, , , _ , _ , . _, ~ _ _ ,, ., . . _, . , _ . _ . _ . .. .. ..... ... . . .. . . .. . . . . . . .. . .
.. . . .. .
~1366~i7
--6--
fluid tigh~ sealing contact with pump housing ~ore 24. Be-
cause of the fluid pressure in the cavity between lip 32 and
groove side 58, seal element 26 is urged generally toward the
opposite side of the groove and the recess around the outer
perimeter of the seal element can be deformed somewhat as
shown in Fig. 6.
A feature of the seal assembly of this invention
lies in the tapered construction of the seal element outer
peripheral surface. This shape permits a seal element to be
10 easily slipped into pump housing bore 24 because the seal is
gradually compressed as it is moved into bore 24 from a
larger diameter portion of pump housing 12. Removal of the
pump body and the seal from the pump housing is also assisted
by the tapered construction because it provides less drag
15 when sliding over pump housing bore 24 than would a non-
tapering or substantially constant diameter seal element.
In use of this seal assembly, it can seal when fluid pressure
is applied from either direction; however, it is preferred
that fluid pressure be applied toward the end having lip 32.
Another feature of the seal assembly of this in-
vention is that the seal element is constructed of a material
which is sufficiently resilient to enable it to be stretched
over a pump housing and into place in the groove. This fea-
ture overcomes the heretofore requirement of pump bodies to
25 be made in several separable segments. Because this seal
assembly does not require a sectionalized separable pump
housing, it makes simpler pump housing designs possible by
eliminating threaded connections, etc. which are necessary
to take them apart. Groove end surface 58 permits the seal
30 ring to be slipped easily into the groove by deforming the
seal ring. To install the seal ring, it is simply slipped
over the outer surface of the pump body and into the groove.
For use in the downhole hydraulic pump, the seal
assembly of this invention has a definite advantage over the
35 seal assemblies previously used because it can be slipped
over the pump body and positioned in the groove. Prior art
constructions, discussed above, have multiple segment pump
bodies that are separated at the seal groove because the seal
elements have an encapsulated rigid support ring which cannot
1136667
--7--
be stretched over ~he pump body. Because this seal element
can be easily stretched over the pump body for installation,
it simplifies the pump design and construction because it
eliminates the need for joints in the pump body.
Although the seal assembly of this invention is
shown with a downhole hydraulic pump,-it can obviously be
used with other equipment where a seal of this nature is
needed or desirable. For example, the seal assembly can be
used where it is desired to seal between two conduits like
10 in couplings.
