U.S. patent application number 12/534243 was filed with the patent office on 2011-02-03 for seal ring with auxiliary ring for earth-boring bit.
This patent application is currently assigned to Baker Hughes Incorporated. Invention is credited to Terry J. Koltermann, Chih C. Lin, Don Quy Nguyen, Gregory W. Peterson, Gregory L. Ricks, Anton Zahradnik.
Application Number | 20110024199 12/534243 |
Document ID | / |
Family ID | 43525951 |
Filed Date | 2011-02-03 |
United States Patent
Application |
20110024199 |
Kind Code |
A1 |
Zahradnik; Anton ; et
al. |
February 3, 2011 |
Seal Ring With Auxiliary Ring for Earth-Boring Bit
Abstract
An elastomeric seal ring is located between each bearing pin and
each cone of an earth-boring bit. An auxiliary ring or band is
imbedded within an annular recess formed in the inner diameter of
the seal ring. A portion of the inner diameter of the seal ring as
well as the auxiliary ring are in dynamic contact with the bearing
pin. The auxiliary ring has a geometric feature that enhances
radial flexibility but prevents it from sealing. The geometric
feature may be a transverse cut, notches in either the inner or
outer diameters, or holes extending between the sides of the
auxiliary ring. The auxiliary ring has lubricating properties.
Inventors: |
Zahradnik; Anton;
(Sugarland, TX) ; Ricks; Gregory L.; (Spring,
TX) ; Peterson; Gregory W.; (Fort Worth, TX) ;
Nguyen; Don Quy; (Houston, TX) ; Lin; Chih C.;
(Spring, TX) ; Koltermann; Terry J.; (The
Woodlands, TX) |
Correspondence
Address: |
Bracewell & Giuliani LLP
P.O. Box 61389
Houston
TX
77208-1389
US
|
Assignee: |
Baker Hughes Incorporated
Houston
TX
|
Family ID: |
43525951 |
Appl. No.: |
12/534243 |
Filed: |
August 3, 2009 |
Current U.S.
Class: |
175/412 |
Current CPC
Class: |
E21B 10/25 20130101 |
Class at
Publication: |
175/412 |
International
Class: |
E21B 10/25 20060101
E21B010/25 |
Claims
1. An earth boring bit having a body with a depending bearing pin,
and a cone rotatably mounted to the bearing pin, the cone having a
plurality of cutting elements, the improvement comprising: an
elastomeric seal ring having an outer portion in sealing engagement
with a seal surface on the cone and an inner portion in sealing
engagement with a seal surface on the bearing pin; an annular
recess extending around one of the portions of the seal ring; an
auxiliary ring carried in the annular recess and having a face
urged by the seal ring into contact with one of the sealing
surfaces; said one of the portions of the seal ring has sections on
opposite lateral sides of the auxiliary ring that sealingly engage
said one of the seal surfaces; and a geometric feature in the
auxiliary ring that enhances radial flexibility of the auxiliary
ring and prevents it from sealing.
2. The bit according to claim 1, wherein the geometric feature
comprises a fluid communication path extending from one of the
lateral sides to the other of the lateral side of the auxiliary
ring.
3. The bit according to claim 1, wherein the geometric feature
comprises: a skive cut extends from one of the lateral sides to the
other of the lateral sides, completely severing the auxiliary ring;
and the skive cut is formed at an acute angle relative to the
lateral sides of the auxiliary ring.
4. The bit according to claim 1, wherein the geometric feature
comprises: at least one hole extending through the auxiliary ring
from one its lateral sides to the other of its lateral sides.
5. The bit according to claim 1, wherein: the auxiliary ring has an
inner diameter and an outer diameter; and the geometric feature
comprises at least one recess on at least one of the diameters that
extends from one of its lateral sides to the other of its lateral
sides.
6. The bit according to claim 1, wherein: the annular recess is
located in the inner portion of the seal ring, and the auxiliary
ring is in sliding engagement with the seal surface on the bearing
pin; and the auxiliary ring is formed of a self-lubricating
material.
7. The bit according to claim 1, wherein the auxiliary ring is
formed of a material that consists essentially of PTFE.
8. The bit according to claim 1, wherein the auxiliary ring is
formed of a material consisting essentially of PTFE and a filler
material selected from one or more of the following: carbon
graphite, glass fibers, and metallic particles.
9. The bit according to claim 1, wherein the auxiliary ring is
formed of PEEK with a filler of PTFE.
10. An earth boring bit, comprising: a body having a depending
bearing pin; a cone having a cylindrical cavity mounted rotatably
on the bearing pin, the cone having an exterior containing a
plurality of cutting elements, the cone and the bearing pin
defining bearing spaces filled with a lubricant; a seal ring of
nitrile rubber, having an outer diameter in sealing contact with
the cavity of the cone and an inner diameter in sealing contact
with the bearing pin, the seal ring having an exterior side exposed
to drilling fluid during operation and an interior side exposed to
lubricant within the bearing spaces; an annular recess formed in
the inner diameter of the seal ring between the interior and
exterior sides; at least one thermoplastic auxiliary ring having an
interior side and an exterior side and located in the annular
recess, the auxiliary ring having an inner diameter urged by the
seal ring into dynamic contact with the bearing pin; and at least
one pathway extending from the interior side to the exterior side
of the auxiliary ring to increase radial flexibility of the
auxiliary ring.
11. The bit according to claim 10, wherein the pathway comprises a
cut that severs the auxiliary ring.
12. The bit according to claim 10, wherein the auxiliary ring has
an outer diameter in contact with a base of the annular recess, and
said at least one pathway comprises a plurality of recesses formed
on one of the diameters of the auxiliary ring.
13. The bit according to claim 10, wherein said at least one
pathway comprises a plurality of holes in the auxiliary ring, each
extending from the interior side to the exterior side.
14. The bit according to claim 10, wherein the inner diameter of
the auxiliary ring after the seal ring and auxiliary ring are
installed in the groove of the cone and prior to installing the
cone on the bearing pin are less than an outer diameter of the
bearing pin; and the pathway allows the auxiliary ring to rapidly
expand during installation of the cone on the bearing pin.
15. The bit according to claim 10, wherein the auxiliary ring is
formed of a material that consists essentially of PTFE.
16. The bit according to claim 10, wherein the auxiliary ring is
formed of a material consisting essentially of PTFE and a filler
material selected from one or more of the following: carbon
graphite, glass fibers, and metallic particles.
17. The bit according to claim 10, wherein the auxiliary ring is
formed of PEEK with a filler of PTFE.
18. An earth boring bit, comprising: a body having a depending
bearing pin; a cone having a cylindrical cavity mounted rotatably
on the bearing pin, the cone having an exterior containing a
plurality of cutting elements; an annular groove in the cylindrical
cavity of the cone; a seal ring of elastomeric material and having
an outer portion in sealing contact with the groove and an inner
portion; an annular recess extending around the inner portion of
the seal ring, defining segments of the seal ring on each side of
the recess that are in dynamic sealing contact with the bearing
pin; an auxiliary ring within the annular recess of the seal ring,
the auxiliary ring having an outer diameter in contact with a base
of the annular recess and an inner diameter in contact with the
bearing pin, the auxiliary ring having an interior side and an
exterior side; the inner diameter of the auxiliary ring after the
seal ring and auxiliary ring are installed in the groove of the
cone and prior to installing the cone on the bearing pin being less
than an outer diameter of the bearing pin; and a cut extending from
the interior side to the exterior side of the auxiliary ring,,
severing and providing radial flexibility to the auxiliary ring to
allow the auxiliary ring to rapidly expand during installation of
the cone on the bearing pin.
19. The bit according to claim 18, wherein prior to installation of
the auxiliary ring and the seal ring in the annular recess in the
cone, the inner diameter of the auxiliary ring is greater than the
outer diameter of the bearing pin.
20. The bit according to claim 18, wherein the auxiliary ring is
formed of a material that has less elasticity than the seal ring.
Description
FIELD OF THE INVENTION
[0001] This invention relates in general to elastomeric seals for
earth boring roller cone bits, and in particular to a seal ring
having an annular recess containing an auxiliary ring of a
different material.
BACKGROUND OF THE INVENTION
[0002] One type of earth-boring bit has a body with at least one
rotatable cone mounted to a depending bearing pin. Typically there
are three cones, each having rows of cutting elements. The cutting
elements may be machined from the metal of the cone, or they may
comprise tungsten carbide inserts pressed into holes in the
exterior of the cone.
[0003] The cone has a cavity that inserts over the bearing pin,
forming a journal bearing. The clearances between the bearing
surfaces are filled with a grease or lubricant. A seal assembly
seals between the bearing pin and the cone near the mouth of the
cone.
[0004] The seal assembly serves to prevent loss of lubricant to the
exterior. Also, the seal assembly serves to exclude debris and
cuttings of the borehole from entering the journal bearing.
Typically the outer diameter of the seal assembly rotates with the
cone and the inner diameter seals against the bearing pin in
dynamic contact.
[0005] Many different seal assemblies have been proposed and used
in the prior art. A variety of shapes of elastomeric seals have
been employed. Elastomeric seals that have different materials on
the inner and outer diameters are known. Elastomeric seals with
carbon fiber fabric on the dynamic portions of the seal are also
known. In addition, metal face seal assemblies including an
elastomer that urges the metal faces together are also known.
SUMMARY OF THE INVENTION
[0006] The seal assembly of this invention comprises a seal ring of
an elastomeric material. The seal ring has an inner portion that
seals against a sealing surface on the bearing pin and an outer
portion that seals against a sealing surface in the cone. At least
one auxiliary ring is mounted in a annular recess formed in one of
the portions of the seal ring and has a face urged by the seal ring
into contact with the sealing surface of the bearing pin or the
cone. The auxiliary ring is of a material that differs from the
seal ring. In one embodiment, the auxiliary ring is located on the
inner portion of the seal ring and provides lubrication to the seal
surface on the bearing pin.
[0007] In the preferred embodiment, the auxiliary ring does not
form a seal against the bearing pin or the cone. It has a
geometrical feature that enhances the radial flexibility of the
auxiliary ring during installation of the cone on the bearing pin.
The geometrical feature is preferably a discontinuity or a pathway
one side to the other of the auxiliary ring. The pathway increases
flexibility of the auxiliary ring but also prevents it from serving
as a seal. In one embodiment, the geometrical feature comprises a
transverse cut that severs the auxiliary ring. In another
embodiment, notches are formed in the inner or outer diameters. In
a third embodiment, holes extend through the width of the auxiliary
ring from its interior side to its exterior side.
[0008] The seal ring may have more than one auxiliary ring. One of
the auxiliary rings may be formed of a self-lubricating material
for providing lubrication to the seal ring. Optionally, an
auxiliary ring may be located on the outer diameter of the seal
ring for frictionally engaging the cone to resist rotation of the
seal ring relative to the cone.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a side elevational view of an earth-boring bit
constructed in accordance with this invention.
[0010] FIG. 2 is an enlarged sectional view of one of the cones and
bearing pins of the earth-boring bit of FIG. 1, illustrating a seal
ring having imbedded auxiliary rings in accordance with the
invention.
[0011] FIG. 3 is a further enlarged sectional view of a portion of
the seal ring and auxiliary rings of FIG. 2.
[0012] FIG. 4 is a schematic sectional view of an inner diameter
portion of one of the auxiliary rings imbedded within the seal ring
of FIG. 2, illustrating a grooved pattern.
[0013] FIG. 5 is a partial sectional view of another embodiment of
a seal ring and auxiliary ring.
[0014] FIG. 6 is a partial sectional view of another embodiment of
a seal ring and auxiliary ring.
[0015] FIG. 7 is a partial sectional view of another embodiment of
a seal ring and auxiliary ring.
[0016] FIG. 8 is a partial sectional view of another embodiment of
a seal ring and auxiliary ring.
[0017] FIG. 9 is a front view of another embodiment of an auxiliary
ring in accordance with the invention.
[0018] FIG. 10 is a side elevational view of the auxiliary ring of
FIG. 9.
[0019] FIG. 11 is an enlarged sectional view of a seal ring having
an auxiliary ring of FIG. 9 installed therein.
[0020] FIG. 12 is a partial front view of another embodiment of an
auxiliary ring.
[0021] FIG. 13 is a transverse cross-sectional view of still
another embodiment of an auxiliary ring.
DETAILED DESCRIPTION OF THE INVENTION
[0022] Referring to FIG. 1, bit 11 has a body 13 with a threaded
upper end for connection to a drill string for rotation about an
axis of body 13. Body 13 has at least one and preferably three bit
legs 15. A bearing pin 17 (FIG. 2) depends downward and inward from
each bit leg 15.
[0023] A cone 19 mounts rotatably to each bearing pin 17. Each cone
19 has a plurality of rows of cutting elements 21. In the example
shown, cutting elements 21 comprise tungsten carbide inserts
pressed into mating holes drilled in the metal of each cone 19.
Alternatively, cutting elements 21 could comprise teeth machined
into the metal of each cone 19.
[0024] A lubricant compensator 23 supplies lubricant to bearing
spaces between the interior of each cone 19 and bearing pin 17.
Lubricant compensator 23 also equalizes the pressure of the
lubricant with the exterior pressure in the borehole.
[0025] Referring to FIG. 2, bearing pin 17 has a cylindrical
journal surface 25 that serves as a bearing for the weight imposed
on drill bit 11 (FIG. 1). A last machined surface 27 encircles
bearing pin 17 on the inside of each bit leg 15. Cone 19 has a
cavity 29 with interior surfaces that mate with the exterior
surfaces of bearing pin 17. Cone 19 and bearing pin 17 have means
for locking cone 19 on bearing pin 17. In this embodiment, the
locking means comprises a plurality of balls 31 located within
mating grooves formed on bearing pin 17 and in cone cavity 29.
[0026] A seal groove 33 is formed in cavity 29 near its mouth. In
this embodiment, groove 33 is rectangular when viewed in
cross-section. Groove 33 has a flat base or outer diameter 33a,
when viewed in transverse cross-section, and two flat sidewalls
33b.
[0027] A seal ring 35 is carried within groove 33 for sealing
lubricant against leakage to the exterior. Seal ring 35 is formed
of an elastomeric material of a type that is conventional for
elastomeric seals for earth-boring bits. Preferably this material
comprises a nitrile rubber such as hydrogenated nitrile butadiene
rubber, but it could be other types of material as well. Seal ring
35 has an outer portion or diameter 37 that seals against groove
33. Seal ring 35 has an inner diameter or portion 41 that may
appear flat when viewed in the transverse cross-section of FIG. 2.
Inner diameter 41 seals and normally rotatably slides against
bearing pin journal surface 25. Seal ring 35 has an exterior side
42a and an interior side 42b, which are shown in parallel planes,
but could be other shapes. Side 42a is on the exterior side of seal
ring 35 and is exposed to drilling fluid during operation through
the clearance between last machined surface 27 and the backface of
cone 19. Side 42b is on the interior side of seal ring 35 and is in
contact with lubricant contained in the bearing spaces. Sidewalls
42a, 42b are spaced slightly from groove sidewalls 33b so as to
accommodate deformation.
[0028] At least one thermoplastic auxiliary band or ring 43 is
located within seal ring 35. Three auxiliary rings 43 are shown in
this embodiment, but the number could be less or more. Referring to
FIG. 3, in this embodiment, each auxiliary ring 43 is located
within an annular recess or annular recess 45 formed in seal ring
inner diameter 41. Auxiliary rings 43 may be bonded within annular
recesses 45 or held by friction. Each auxiliary ring 43 has a
contacting face 47 on its inner diameter that is urged by seal ring
35 into dynamic contact with bearing pin journal surface 25.
[0029] In this example, auxiliary rings 43 are spaced apart from
each other along the axis of bearing pin 17. The spacing results in
annular sections 49 of seal ring 35 located on each lateral side of
each auxiliary ring 43, each section 49 sealing against bearing pin
journal surface 25. One of the sections 49 is located between
exterior side 42a and its closest auxiliary ring 43 and another
between interior side 42b and its closest auxiliary ring 43. Also,
a section 49 exists between each of the auxiliary rings 43. The
width of seal ring 35 from interior side 42b to exterior side 42a
is greater than the total combined width of the contacting face 47
of each auxiliary ring 43.
[0030] In FIG. 2, auxiliary rings 43 are shown with a rectangular
configuration when viewed in transverse cross-section, each having
a cylindrical contact face 47 and a cylindrical outer diameter.
However, other cross-sectional configurations are feasible. In FIG.
3, auxiliary rings 43 are shown with a circular configuration.
[0031] Auxiliary rings 43 also slidingly engage journal surface 25,
but do not form a sealing engagement with journal surface 25
because they serve other purposes. Auxiliary rings 43 may be formed
of a material containing a lubricant additive for providing
lubrication to journal surface 25. In the preferred embodiment,
auxiliary rings 43 are formed of one of the following materials:
polytetrafluoroethylene ("PTFE"), polyaryletheretherketone or
polyether ether ketone ("PEEK"), polyphenylenesulfide and fiber
reinforced composites thereof. For lubrication, the material may
contain more than 20% by volume lubricant additive. PTFE is a
material that lubricates, but PEEK is not self-lubricating. As
example, the material of auxiliary rings 43 could consist
essentially of the following: 100% virgin PTFE; PTFE with the
balance being a filler up to about 25% of carbon graphite, glass
fibers, or metallic particles; or PEEK with a filler of PTFE of 15%
or more. However, other materials are also feasible. The material
should be resistant to relative high temperatures and resistant to
abrasion due to cuttings and other erosive particles in the
drilling fluid. Typically the material of auxiliary rings 43 is not
as flexible as the material of seal ring 35.
[0032] The lubricant additive of auxiliary ring 43 flows or is
imparted to journal surface 25 so as to lubricate the portions of
journal surface 25 dynamically engaged by seal ring 35. Material
thus is intended to be dispersed or worn away from faces 47 of
auxiliary rings 43. Auxiliary rings 43 intended for lubrication
thus have a less wear resistance than seal ring 35. Alternately,
auxiliary rings 43 could be intended to exclude debris, and in that
instance may or may not have lubricant additives.
[0033] Micro texturing may be formed in the inner diameters 47 of
each auxiliary ring 43. Micro texturing comprises very shallow
recesses formed in the surface by known techniques, such as by
laser. A wide variety of texturing is feasible. As an example, FIG.
4 shows generally sinusoidal grooves 51 extending in three rows
around the inner diameter 47. Grooves 51 tend to retain lubricant
on journal surface 25.
[0034] In operation, as bit 11 rotates, each cone 19 will rotate
about its bearing pin 17 (FIG. 2). Each seal ring 35 will tend to
rotate with its cone 19 and sealingly engage journal surface 25 of
bearing pin 17 in dynamic sliding contact. Auxiliary rings 43 also
engage journal surface 25 in dynamic contact but not sealing
contact.
[0035] In FIG. 5, a cone 53 is mounted on a roller bearing pin 55,
generally as in the first embodiment. Seal ring 57 has an inner
portion that seals in rotating dynamic contact with bearing pin
journal surface 59 and an outer portion that seals against cone
cavity 61. In this embodiment, a single auxiliary ring 63 is
mounted in an annular recess on the inner portion of seal ring 57.
Auxiliary ring 63 has a generally flat face that contacts but does
not seal against journal surface 59. The remaining cross-sectional
shape of auxiliary ring 63 is curved and convex. Portions of the
inner portion of seal ring 57 on the interior and exterior sides of
auxiliary ring 63 sealingly engage journal surface 59.
[0036] In FIG. 6, a cone 65 is mounted on a bearing pin 67
generally as in the first embodiment. Seal ring 69 has an inner
portion that seals in rotating dynamic contact with bearing pin
journal surface 71 and an outer portion that seals against cone
cavity 73. In this example, there are two auxiliary rings 75, 77,
and each has a contacting face with a different configuration.
Auxiliary ring 75 is located on the exterior side of auxiliary ring
77 and has a convex or rounded cross-sectional shape, including its
contacting face. Auxiliary ring 77 may be formed of a material that
provides lubrication and may be softer than auxiliary ring 75 and
seal ring 69.
[0037] In FIG. 7, a cone 79 is mounted on a bearing pin 81
generally as in the first embodiment. Seal ring 83 has an inner
portion that seals in rotating dynamic contact with bearing pin
journal surface 85 and an outer portion that seals against a groove
87 in cone 79. Groove 87 is triangular shaped in this example. Seal
ring 83 has a flat exterior side 89a and a flat interior side 89b
that wedge against the sides of annular recess 87. A single
auxiliary ring 91 in shown on the inner portion of seal ring 83 in
engagement with journal bearing surface 85, but more than one is
feasible. Auxiliary ring 91 may be of various shapes and is shown
to have a shape generally like that of auxiliary ring 63 in FIG.
5.
[0038] In FIG. 8, a cone 93 is mounted on a bearing pin 95
generally as in the first embodiment. Seal ring 97 has an inner
portion that seals in rotating dynamic contact with bearing pin
journal surface 99 and an outer portion that seals against a groove
101 in cone 93. Two auxiliary rings 103 are shown on the inner
diameter of seal ring 97. Auxiliary rings 103 are shown with shapes
similar to that of auxiliary ring 63 in FIG. 5.
[0039] An outer auxiliary ring 105 is shown embedded within an
annular recess on the outer diameter of seal ring 97 and in
frictional engagement with the base of cone groove 101. Outer
auxiliary ring 105 serves to frictionally grip cone 93 to resist
slippage and rotation of seal ring 97 relative to cone 93. Outer
auxiliary ring 105 may be formed of a material that has good
gripping properties, the hardness of which may be less than seal
ring 97. Outer auxiliary ring 105 may have a variety of shapes, but
is shown as having a shape similar to auxiliary ring 63 of FIG. 5.
Although not expected, it is possible that one prefers to cause
seal ring 97 to remain stationary on bearing pin 95 while cone 93
rotates. If so, auxiliary ring 105, having a high surface friction,
would be located on the inner diameter of seal ring 97 and one or
more auxiliary rings 103 for retarding wear and/or enhancing
lubrication would be located on the outer diameter of seal ring
97.
[0040] FIGS. 9-12 illustrating auxiliary rings that have more
flexibility so as to be rapidly expanded in diameter when the cone
is being installed on the bearing pin. Auxiliary ring 107 may be
any one of the auxiliary rings 43, 63, 75, 77, 91, 103 or 105
previously discussed. Auxiliary ring 107 has a geometric feature to
enhance radial flexibility, which in this embodiment comprises a
transverse cut 109 that completely severs it, creating two ends
that abut each other. As shown in FIG. 10, cut 109 is preferably a
skive cut, extending in a straight line from one side 111 to the
other side 113. Cut 109 is formed at an acute angle 115 relative to
a plane containing either side 111 or side 113. The angle may vary
and is shown to be about 10 degrees. Cut 109 is thus also at an
angle relative to the axis 117 of auxiliary ring 107. Cut 109 forms
a fluid communication pathway that prevents auxiliary ring 107 from
sealing against journal surface 25 of bearing pin 17 (FIG. 2).
[0041] Referring to FIG. 11, auxiliary ring 107 is shown installed
within an annular recess 119 in the inner diameter 120 of a seal
ring 121. Seal ring 121 may be similar to seal rings 35, 57, 69,
83, or 97 previously discussed. In this example, seal ring 121 has
a high aspect ratio, which is its radial thickness compared to its
axial width. Seal ring 121 may have ribs 123 on each side to
stabilize ring 121 within its groove (not shown). Seal ring 121 is
shown in a relaxed position before installation in its groove.
Prior to installing seal ring 121 in groove 33 of cone 19 (FIG. 2),
the face or inner diameter 125 of auxiliary ring 107 is recessed
within annular recess 119. Once installed between cone groove 33
and bearing pin journal surface 25(Fig. 2), inner diameter 125 of
auxiliary ring 107 will be in contact with bearing pin journal
surface 25 and flush with inner diameter 120 of seal ring 121.
[0042] Auxiliary ring 107 may be installed in annular recess 119
without attempting to stretch inner diameter 120 of seal ring 121.
Instead, auxiliary ring 107 is squeezed or forced radially inward
so that its outer diameter 127 is smaller than inner diameter 120
of seal ring 121. While doing so, the ends of auxiliary ring 107
formed by cut 109 will slide past and overlap each other. Once in
alignment with annular recess 119, the radial inward force is
removed, allowing auxiliary ring 107 to resiliently spring into
annular recess 119. Once in annular recess 119, outer diameter 127
of auxiliary ring 107 will be in contact with the inner diameter of
annular recess 119 and its inner diameter 125 will be slightly
recessed, as shown in FIG. 11.
[0043] Normally, after installing auxiliary ring 107 in annular
recess 119, seal ring 121 would then be placed in a cone seal
groove such as seal groove 33 of cone 19 (FIG. 2). Prior to
installing seal ring 121 in seal groove 33, inner diameter 125 is
slightly greater than the outer diameter of journal surface 25
(FIG. 2). After installation in groove 33, the outer diameter or
base 33a of groove 33 will push the inner diameter 120 of seal ring
121 and the inner diameter 125 of auxiliary ring 107 radially
inward to a diameter smaller than the outer diameter of journal
surface 25. The smaller inner diameters create an interference,
which for example, may be about 0.010 inch on a side.
[0044] The installer will supply sufficient force and optionally
impacts to force cone 19 over bearing pin 17. Journal surface 25
will force the seal ring and auxiliary ring inner diameters 120 and
125 to rapidly expand outward as cone 19 moves onto bearing pin 17.
Unlike seal ring 121, auxiliary ring 107 may be formed of a
material that is less elastic and does not quickly expand. Cut 109
allows the rapid radial expansion to occur without any chance of
damaging auxiliary ring 107. After installation on bearing pin 17,
seal ring 37 will be squeezed against journal surface 25 to a
desired amount, typically from 5 to 15%. Inner diameter 125 of
auxiliary ring 107 will be in contact with journal surface 25.
[0045] Cut 109 will prevent auxiliary ring 107 from sealing against
bearing pin journal surface 25 because it forms a fluid
communication path. Any pressure differential between its sides 111
would allow fluid to flow past auxiliary ring 107. However,
auxiliary ring 107 is not intended to seal as this is done by seal
ring 121. Auxiliary ring 107 will not be exposed to a pressure
differential from one of its sides 111 to the other as long as seal
ring 121 is sealing properly.
[0046] There are alternatives to allow the rapid expansion of
auxiliary ring 107 rather than forming a cut. For example, FIG. 12
shows an auxiliary ring 129 with one or more notches 131 formed in
the inner diameter of auxiliary ring 129. Alternately, notches 131
could be formed in the outer diameter. Notches 131 are spaced apart
from each other around the circumference of auxiliary ring 129 and
extend from one lateral side to the other. Notches 131 would reduce
the radial thickness of auxiliary ring 107 where they occur, making
auxiliary ring 129 more flexible. Notches 131 also form fluid
communication pathways between the lateral sides of auxiliary ring
129.
[0047] FIG. 13 shows a sectional view of an auxiliary ring 133. In
this embodiment, at least one and preferably several holes 135 are
formed in auxiliary ring 133. Each hole 135 axially extends from an
interior side to an exterior side of auxiliary ring 133. Preferably
holes 135 are spaced equally around the circumference of auxiliary
ring 133. Holes 135 increase the radialy flexibility of auxiliary
ring 133 to allow it to rapidly be expanded in diameter. Holes 135
provide fluid communication pathways across auxiliary ring 133,
preventing sealing across auxiliary ring 107 to occur.
[0048] The term "auxiliary" has been used in connection with the
rings, whether designed to exclude and trap debris, or to
lubricate, or to resist rotation. This term is used only for
convenience and not in a limiting manner.
[0049] The invention has significant advantages. Auxiliary rings
with lubricating properties may be used to add lubrication, which
reduces heat and prolongs the life of the seal ring. Auxiliary
rings with gripping properties may be used to resist rotation of
the seal ring. Auxiliary rings may also serve to exclude
debris.
[0050] While the invention has been shown in only a few of its
forms, it should be apparent to those skilled in the art that it is
not so limited but is susceptible to various changes without
departing from the scope of the invention.
* * * * *