CROSS REFERENCE TO RELATED APPLICATION
This application claims the benefit of U.S. Provisional Application No.
61/639,560, filed April 27,2012, which is incorporated by reference herein in its
entirety.
The subject matter of this application may be related to the subject matter of
copending U.S. Patent Application No., titled "MITIGATING VORTEX PUMPING
EFFECT UPSTREAM OF OIL SEAL," filed on even date herewith, which is
incorporated by reference herein its entirety.
BACKGROUND
The subject matter disclosed herein relates generally to apparatuses and
methods for retaining fluid lubricant, such as oil, in an oil sump and/or its drain path.
More specifically, but not by way of limitation, some example embodiments relate to
apparatuses and methods for maintaining design gaps during axial exciirsions of a
shaft while also improving the limitation of oil leakage, for example from in a sump
of a turbine engine.
In a turbine engine, air is pressurized in a compressor and mixed with fuel in a
combustor for generating hot combustion gases which flow downstream through
turbine stages. These turbine stages extract energy from the combustion gases. A
high pressure turbine includes a first stage nozzle and a rotor assembly including a
disk and a plurality of turbine blades. The high pressure turbine first receives the hot
combustion gases fi-om the combustor and includes a fu-st stage stator nozzle that
directs the combustion gases downstream through a row of high pressiure turbine rotor
blades extending radially outwardly firom the first rotor disk. In a two stage turbine, a
second stage stator nozzle is positioned downstream of the first stage blades followed
in turn by a row of second stage turbine blades extending radially outwardly fi"om a
second rotor disk. The stator nozzles turn the hot combustion gas in a manner to
enhance extraction at the adjacent downstream turbine blades.
The first and second rotor disks are joined to the compressor by a
corresponding high pressure rotor shaft for powering the compressor during
operation. The high pressure turbine powers rotation of the compressor to create
compressed air for combustion, thus continuing the process. A multi-stage low
pressure turbine follows axially the two stage high pressure turbine and is typically
joined by a second shaft coaxial with the first shaft to a fan disposed upstream from
the compressor in a typical turbo fan aircraft engine configuration for powering an
aircraft in flight.
As the combustion gasses flow downstream through the turbine stages, energy
is extracted therefrom and the pressure of the combustion gas is reduced while
providing fan rotation for aviation thrust. Alternatively, the combustion gas is used to
power the compressor and a turbine output shaft for power and marine use. In this
manner, fiiel energy is converted to mechanical energy of the rotating shaft to power
the compressor and supply compressed air needed to continue the process.
During rotation of the core of the turbine engine, and at some operating
temperatures, axial excursions of the rotor shaft and parts connected thereto may
sometimes occur. Seal teeth structures have been used to seal areas of differential
pressure or oil and air and maintain pressure for pressurized seals. Ensuring that a
design gap over a discourager tooth is always maintained during these axial
excursions often required extending the opposed sealing surface, which could be
problematic to the design of surrounding components.
Of additional concern, at some operational design altitudes, for example
51,000 feet, air is of very low density. Such thin air may not have enough force
against the direction of oil seals so as to fiiUy inhibit leakage from the sump.
The problems: Oil leakage across seals may be disadvantageous for a turbine
engine. Axial excursions of the rotor and connected structures may cause an
associated sealing structure to lose a design or seal gap with an opposed land. In
some oil sump configurations, excessive pressure differential around an oil sump may
cause undesirable oil leakage.
BRIEF DESCRIPTION
At least one solution for the above-mentioned problem(s) is provided by the
present disclosure to include example embodiments, provided for illustrative teaching
and not meant to be limiting.
Some example embodiments according to at least some aspects of the present
disclosure may involve an oil sump and the prevention of oil leakage fi-om the sump,
for example through a sump seal. Pressurized air flow may be directed through a
pathway and over a widened discourager tooth. Some example widened discourager
teeth may include a tip having an extended axial length for maintaining a design gap
during axial excursions of the rotor shaft, to which tiie discourager tooth is connected.
Some example widened discourager teeth may provide an elongated region of high
velocity air flowing past, which may induce higher impulse. This higher impulse may
approach oil particles which may have moved beyond an oil seal (e.g., a labyrinth
seal) and may be more capable of changing oil particle direction to prevent oil
leakage over the discourager tooth.
An example oil sump seal pressurization apparatus for a turbine engine
according to at least some aspects of the present disclosure may include a nonrotating
oil sump housing a bearing, the bearing supporting a rotatable shaft; an oil
seal at least partially isolating an interior of the oil sump, the oil seal operatively
acting between a non-rotating structural member of the sump and the rotatable shaft; a
passage arranged to supply pressurization air to an outward side of the oil seal with
respect to the oil sump; a drain arranged to allow draining of oil and venting of at
least some of the pressurization air, the drain being positioned axially between the
passage and the oil seal; a discourager tooth disposed on the shaft and extending
radially outward towards a non-rotating land, the land being disposed axially between
the passage and the drain, the discourager tooth being spaced apart from the land in a
generally radial direction by a gap having a width, the discourager tooth including an
upper surface having a width; and/or a first adjacent tooth disposed on the shaft and
extending radially outward from the shaft. The discourager tooth width may be at
least about 1.5 times a width of the first adjacent tooth.
An example oil sump seal pressurization apparatus for a turbine engine
according to at least some aspects of the present disclosure may include a nonrotating
oil sump housing, a bearing, the bearing supporting a rotatable shaft; an oil
seal at least partially isolating an interior of the oil sump, the oil seal operatively
acting between a non-rotating structural member of the sump and the rotatable shaft; a
passage arranged to supply pressurization air to an outward side of the oil seal with
respect to the oil sump; a drain arranged to allow draining of oil and venting of at
least some of the pressurization air, the drain being positioned axially between the
passage and the oil seal; and/or a discourager tooth disposed on the shaft and
extending radially outward towards a non-rotating land, the land being disposed
axially between the passage and the drain, the discourager tooth being spaced apart
from the land in a generally radial direction by a gap having a width, the discourager
tooth including an upper surface having a widtii.
An example oil sump seal pressurization apparatus for a turbine engine
according to at least some aspects of the present disclosure may include a nonrotating
oil sump housing a bearing, the bearing supporting a rotatable shaft; an oil
seal at least partially isolating an interior of the oil sump, the oil seal operatively
acting between a non-rotating structural member of the sump and the rotatable shaft; a
passage arranged to supply pressurization air to an outward side of the oil seal with
respect to the oil sump; a sump pressurization cavity disposed at least partially aroimd
the oil sump, the sump pressurization cavity comprising a volume arranged to supply
the pressurization air to the passage; a non-rotatable windage shield disposed within
the sump pressurization cavity between the volume and a rotatable arm disposed on
the shaft; a pressurization tooth fluidicly interposing the passage and the rotatable
arm, the pressurization tooth restricting flow of the pressurization air fi-om the
passage towards the rotatable arm; a drain arranged to allow draining of oil and
venting of at least some of the pressurization air, the drain being positioned axially
between the passage and the oil seal; and/or a discourager tooth disposed on the shaft
and extending radially outward towards a non-rotating land, the land being disposed
axially between the passage and the drain, the discourager tooth being spaced apart
from the land in a generally radial direction by a gap having a width, the discourager
tooth including an upper surface having a width.
All of the above outlined features are to be understood as exemplary only and
many more features and objectives of the invention may be gleaned fi-om the
disclosure herein. Therefore, no limiting interpretation of this summary is to be
understood without fiirther reading of the entire specification, claims, and drawings
included herewith.
BRIEF DESCRffTION OF THE DRAWINGS
The subject matter for which patent claim coverage is sought is particularly
pointed out and claimed herein. The subject matter and embodiments thereof,
however, may be best understood by reference to the following description taken in
conjunction with the accompanying drawing figures in which:
FIG. 1 is a side section view of an example turbine engine;
FIG. 2 is a side section view of an example oil sump and related seal structure;
FIG. 3 is a detail section view of a labyrinth oil seal and adjacent discourager
tooth which rotates with a high pressure turbine shaft; and
FIG. 4 is a detailed cross section view of an example widened discourager
tooth, all in accordance with at least some aspects of the present disclosure.
DETAILED DESCRIPTION
In the following detailed description, reference is made to the accompanying
drawings, which form a part hereof. In the drawings, similar symbols typically
identify similar components, imless context dictates otherwise. The illustrative
embodiments described in the detailed description, drawings, and claims are not
meant to be limiting. Other embodiments may be utilized, and other changes may be
made, without departing from the spirit or scope of the subject matter presented here.
It will be readily imderstood that the aspects of the present disclosure, as generally
described herein, and illustrated in the figures, can be arranged, substituted,
combined, and designed in a wide variety of different configurations, all of which are
expUcitly contemplated and make part of this disclosure.
Reference now will be made in detail to embodiments provided, one or more
examples of which are illustrated in the drawings. Each example is provided by way
of explanation, not limitation of the disclosed embodiments. In fact, it will be
apparent to those skilled in the art that various modifications and variations can be
made in the present embodiments without departing from the scope or spirit of the
disclosure. For instance, features illustrated or described as part of one embodiment
can be used with another embodiment to still yield further embodiments. Thus it is
intended that the present invention covers such modifications and variations as come
within the scope of the appended claims and their equivalents.
Some example embodiments according to at least some aspects of the present
disclosure may relate to a gas turbine engine, wherein a combustor bums fuel mixed
with compressed air and discharges a hot combustion gas into a high pressure turbine.
Apparatus and methods according to at least some aspects of the present disclosure
may aid to limit the problems associated with axial excxursions of a rotor and
associated components. Additionally, apparatus and methods according to at least
some aspects of the present disclosure may aid to limit oil leakage through various
seal types, including but not limited to, a labyrinth oil seal at an oil sump.
The terms fore (or forward) and aft are used with respect to the engine axis
and generally mean toward the front of the turbine engine or the rear of the turbine
engine in the direction of the engine axis, respectively.
FIGS. 1-4 illustrate various example oil sump seal pressurization apparatuses
and methods of maintaining oil within an oil sump and/or limiting the effects of axial
excursions of the rotor and a discourager tooth connected thereto.
Referring initially to FIG. 1, a schematic side section view of a gas turbine
engine 10 is shown having an engine inlet end 12, a compressor 14, a combustor 16
and a multi-stage high pressure turbine 20. The gas turbine 10 may be used for
aviation, power generation, industrial, marine, or like applications. The gas turbine
10 is generally axis-S5m]metrical about axis 24. Depending on the usage, the engine
inlet end 12 may alternatively contain multistage compressors rather than a fan. In
operation, air enters through the air inlet end 12 of the engine 10 and moves through
at least one stage of compression where the air pressure is increased and directed to
the combustor 16. The compressed air is mixed with fiiel and burned providing the
hot combustion gas which exits a combustor 16 toward the high presswe turbine 20.
At the high pressure turbine 20, energy is extracted from the hot combustion gas
causing rotation of turbine blades which in turn cause rotation of the high pressure
shaft 26, which passes toward the front of the engine to continue rotation of the one or
more compressors 14. A second shaft, low pressure shaft 28, mechanically couples a
low pressure turbine 21 and a turbo fan 18 or inlet fan blades, depending on the
turbine design.
The high pressure shaft 26 rotates about the axis 24 of the engine. The high
pressure shaft 26 extends through the turbine engine 10 and is supported by bearings.
The bearings operate in oil sumps to cool parts during the high speed revolution.
Fluid leakage in and around rotating parts may significantly increase fuel
consumption and reduce engine efficiency resulting in undesirable operating
parameters for the turbine engine. Additionally, high pressiu-e gasses, such as
combustion gasses within the turbine and compressor discharge area, may leak from
high pressure areas to low pressure areas and controlling such leakage is preferred.
Control or inhibition of such leakage is performed in a variety of manners including,
for example, labyrinth seals and brush seals positioned between areas of differential
pressure. Over time, however, increased exposure to these high pressure and thermal
areas may result in loss of seal effectiveness.
In gas turbine engines it is frequently necessary or desirable to isolate a
volume, which may include one or more rotating parts in order to confine a fluid, such
as oil, and to prevent such fluid from flowing into adjacent areas or flowing out of the
volume. For example, in a gas turbine engine, it may be necessary to confine a liquid
lubricant associated with shaft bearings to a volume surrounding the bearing in order
to prevent amounts of the fluid or oil from leaking from the volume or sump. An
exemplary sump area 30 is depicted at an aft end of Ihe shaft 26. The sump area 30
includes a widened discourager tooth further to compensate for axial movement or
excursions of the shaft 26 and prevent oil leakage. Although an example embodiment
is described for this specific area, similar apparatus may be used with or applied to a
multitude of locations. Such description should therefore not be considered limiting.
In oil sump structures, pressurized air is utilized to pass aroimd or through the sump
area in order to pressurize seals and prevent leakage as well as cool oil or operating
components.
Referring now to FIG. 2, a side view of an aft oil sump area 30 is shown. In
the aft area of the turbine engine 10, one or more sumps 32 may be located which
service bearings providing for rotation of a radially itmer or low pressure shaft 28 and
a radially outer shaft or high pressure shaft 26. The high pressiu-e shaft 26
interconnects the high pressure turbine 20 and high pressure compressor 14 while the
inner shaft interconnects the low pressure compressor and low pressure turbine. The
low pressure shaft 28 extends coaxially through the high pressiure shaft 26 and may
rotate in either the same direction or opposite that of the high pressure shaft 26.
During operation of the turbine engine, the shafts may rotate at different speeds
relative to each other.
As shown in FIG. 2, at the left-hand side of the figure, a high pressure turbine
20 is represented by a rotor assembly 22 which is connected to the high pressure shaft
26 extending about the center line axis 24. The rotor assembly 22 forms a portion of
the high pressure turbine 20 and rotates with the high pressure shaft 26.
Axially aft of the rotor assembly 22 is an oil sump 32, which is defined by a
plurality of generally annular structural members 40,44 and which may be nonrotating.
These members generally define a volume above the high pressure shaft 26
wherein bearing assembly 80 operates and oil is provided for cooling and lubrication
of at least one shaft bearing, and a sump pressurization cavity comprising volumes 72,
46,62 (which may be at least partially defined by structural members 34, 36,38,40,
42,44 and 66) that at least partially surroimd the sump 32, through which
pressurization air 90 is supplied to the sxmip seals 68,70. Depending fi:om member
38 is a sump forward air seal land 50 having a rub strip 52 located along a lower
surface thereof. Beneath the sump forward air seal land 50 and engaging the rub strip
52 is a sump forward air labyrinth seal 54. Labyrinth seal 54 includes a plurality of
seal teeth which extend radially upwardly to engage the rub strip 52. In some
example embodiments, adjacent to the seal 54 may be an arm 56 and/or a nonrotatable
windage shield 60. Such an arrangement may provide a by-pass passage 62
which may be at least partially separated rotating air created by arm 56.
A pressurization tooth 64 may be disposed on shaft 26 generally radially
inward fi-om windage shield 60. To the aft of pressurization tooth 64 is a labyrinth
seal 68 which defines a forward seal for the oil sump 32. Pressurization tooth 64 may
fluidicly interpose passage 63 and rotatable arm 56 and/or may generally restrict flow
of pressurization air 90 from passage 63 towards rotatable arm 56. An aft seal 70
defines an opposite seal for the oil sump 32. Within the sump 32 is a bearing
assembly 80, for example a roller bearing assembly at least partially supporting
rotatable shaft 26.
As shown in the figure, pressurization air 90 moves radially upwardly into the
cavity or flow path 72 aft of the sump 32. The flow 90 moves upwardly through the
flow path 72 and through an aperture in the structural member 40 and, for purposes of
this description, turns forward relative to the axial direction of the engine 10,
generally toward the windage shield 60. In the structural member 42, the flow 90
passes through a member 66 and moves downwardly through the by-pass flow path
62 extending along the aft side of the windage shield 60.
In some applications, it may be desirable that the pressures at the flow path
area 72 adjacent to aft seal 70 and the pressure at the labyrinth oil seal 68 be close to
equal or that the pressure at the labyrinth oil seal 68 be slightly lower than the
pressure at the aft seal 70. The air flow 90 at the seal 68 may help create a barrier to
oil movement out from the smnp 32. When the pressure differential between aft seal
70 and the forward seal 68 is too high, oil from the sump 32 could leak beyond the
forward oil seal 68. Thus, in some example embodiments, the pressure differential
around the oil sump 32 may be limited, thereby promoting proper seal performance
and promoting oil leakage from the seals.
Some example embodiments may include a widened discourager tooth 74 in
the flow path of pressurization air 90 near oil seal 68. Widened discourager tooth
may increase the impulse of pressurization air 90 near the seal 68, which may cause
oil beyond the seal 68 to move to a drain 65 (FIG. 3), represented in broken line.
Referring now to FIG. 3, a detailed view of the flow of pressurization air 90 at
the discoiirager tooth 74 is depicted adjacent the oil sump 32. The windage shield 60
extends upwardly above a pressurization tooth 64. The detailed figure shows how
windage shield 60 directs a portion of the flow of the pressurization air 90 to the aft
side of the shield 60 (e.g., by-pass passage 62) and through a passage 63.
As the pressurization air 90 flows aft toward the labyrinth seal 68, pressure is
maintained at the seal 68 to at least partially isolate the interior of sump 32 and to
prevent oil from stmip 32 from moving forward through the seal 68 and leaking.
Since the labyrinth seal 68 fimctions as a seal for the oil sump 32, the pressurized
flow 90 on the forward side of the seal 68 (e.g., the outward side of the oil seal with
respect to the oil siunp) prevents the passage of oil from the aft side of the oil seal 68
to the forward side. Generally, oil seal 68 may operatively act between a non-rotating
structural member of the sump (e.g., structural member 44) and rotatable shaft 26.
Disposed between the passage 63 for supplying pressurization air 90 and the
oil seal 68 is the discourager tooth 74. The discourager tooth 74 may limit the
10
passage of oil particles that may have leaked past the labyrinth seal 68, and that may
tend to flow over the tooth 74 in the direction opposite of the direction of the flow of
pressurization air 90. Such passage of oil, in the opposite direction of flow of
pressurization air 90, may be undesirable. The discourager tooth 74 may maintain a
design gap from an opposed land 76. In some example embodiments, discourager
tooth 74 may be sufficiently wide to maintain such gap even during axial excursions
of the rotor shaft, which may be normal during operation. In some example
embodiments, the gap may be maintained even if a portion of the tooth 74 were to
extend axially (either forward or aft;) beyond the corresponding stationary land 76.
The discourager tooth 74 may be formed of opposed generally radially
extending surfaces 71, 73 which are joined at a radially outward end by a tooth
surface 75. The tooth surface 75 may have a width which is at least twice the width
of adjacent teeth 64 and teeth 69 of seal 68.
As shown in the figures, the pressurized air 90 passes through the passage 63
and turns aft toward the oil seal 68. After passing over the discourager tooth 74, the
air flow pressurizes the teeth 69 of labyrinth seal 68, preventing leakage of oil from
the sump 32. It should be noted that while the seal 68 is described, this is exemplary
of one area and various other seals and seal types may be utilized in concert with the
discourager tooth 74. The pressurized flow 90 is depicted moving through the seal 68
and into the sump 32, for the purpose of limiting oil from passing in the opposite
direction of flow 90 (leaking).
However, on occasion it is possible that oil can leak beyond the seal 68. The
discourager tooth 74 may provide a barrier to such leakage. During operation, the
pressurized air 90 accelerates when passing over the discourager tooth 74. Otherwise
stated, the velocity increases in this area. The present disclosure contemplates that
the impulse may be regarded as a change in momentum of an object to which a force
is applied. This is expressed as I = FAt = mAv, where:
I is impulse;
F is the force applied;
t is the time interval over which the force is applied; and,
V is the velocity of the object at a time.
11
Hence, the higher the velocity and longer the duration of the air flowing across
the discourager tooth, the more impulse the air can impart on a leaked particle of oil.
The longer the region of high velocity air over the tooth surface 75, the greater the
time interval t over which the force is applied, and the higher the impulse. As a
result, the increased impulse created by the discourager tooth 74 inhibits fiirther
forward progression of leaked oil and instead re-directs that oil back through the seal
68 and into the sump 32 or upwardly through an aperture 65 by changing momentum
of the particle. Aperture 65 may operate as a drain for leaked oil and/or may vent at
least some of the pressurization air 90. Aperture 65 may be positioned axially
between passage 63 and oil seal 68. In either event, the leaked oil is handled in a
predictable manner.
FIG. 4 is a detailed cross section view of an example widened discourager
tooth 74, according to at least some aspects of the present disclosure. Discourager
tooth 74 upper tooth surface 75 may have a width 175, which may be measured in a
generally axial direction with respect to engine axis 24 (FIG. 1). Discourager tooth
74 may be disposed on shaft 26 and/or may extend generally radially outward towards
a non-rotating land 76, which may have a length 176, which may be measured in a
generally axial direction with respect to engine axis 24 (FIG. 1). Land 76 may be
disposed axially between passage 63 and drain (aperture) 65. Discowager tooth 74
may be spaced apart, in a generally radial direction with respect to engine axis 24
(FIG. 1), from land 76 by a gap 77 having a width 78. Adjacent teeth on high
pressure shaft 26 (e.g., pressurization tooth 64 and/or oil seal 68 teeth 69) may have
respective widths 164,169, which may be measured in a generally axial direction
with respect to engine axis 24 (FIG. 1).
In some example embodiments, the discourager tooth 74 may be at least about
1.5, 2.0, or 2.5 times the width of adjacent teeth on the high pressure shaft 26, such as
the pressurization tooth 64 and the exemplary teeth 69 of the labyrinth seal 68. In
other words, in some example embodiments, discourager tooth width 175 may be at
least about 1.5 times pressurization tooth width 164 and/or seal tooth width 169. In
some example embodiments, discourager tooth width 175 may be at least about 2.0
times pressurization tooth width 164 and/or seal tooth width 169. In some example
12
embodiments, discoxirager tooth width 175 may be at least about 2,5 times
pressurization tooth widtii 164 and/or seal tooth width 169.
In some example embodiments, the upper tooth surface width 175 may be
great enough such that at least some portion of the discourager tooth upper surface 75
will always be substantially directly radially underneath the non-rotating land 76
during any anticipated axial excursion of the rotor shaft 26. Such length may be
determinable through engineering methods and analysis known to one skilled in the
art. The discourager tooth 74 therefore may compensate for axial excursions which
are capable of occurring during operation. For example, the rotor shaft 26 (FIG. 2)
due to thermal expansion, rotation, or shocks may move a distance, for example, of
0.1 inches forward. However, prior to the shaft motion due to thermal expansion,
rotation, or shock, the aft edge of the upper tooth surface 75 of the exemplary
discourager tooth 74 will be more than 0.1 inches from the forward edge of the nonrotating
land 76 in a generally axial direction. For example, the rotor shaft 26 (FIG.
2) due to thermal expansion, rotation, or shocks may move a distance, for example, of
0.1 inches aft. However, prior to the shaft motion due to thermal expansion, rotation,
or shock, the forward edge of the upper tooth siuface 75 of the exemplary discoiurager
tooth 74 will be more than 0.1 inches fi"om the aft edge of the non-rotating land 76 in
a generally axial direction. Therefore, while a portion of the tooth siuiace 75 may
extend beyond the land 76 in a fore or aft direction, the width 78 of design gap 77
between the discourager tooth 74 and land 76 may still be maintained. As a result,
flow of pressurization air 90 through gap 77 may be generally more consistent (e.g.,
pressure loss and/or velocity), which contribute to more predictable oil seal 68
performance.
As an unexpected result, in some example embodiments, the stationary land 76
opposite the discourager tooth 74 may need not be longer than usual. As this was a
method of compensating for the axial excursion, such method led to longer parts
which in turn meant higher weights. However, some example embodiments
according to at least some aspects of the present disclosure may allow shortening of
the stationary parts without loss of the design gap, as described herein.
According to some example embodiments, the discom^ager tooth 74 comprises
opposed sides extending to an upper tooth siirface 75. The upper tooth surface 75
13
may be wider (e.g., at least twice the width) than adjacent seal 68 teeth 69 and/or a
pressurization tooth 64. The upper tooth surface 75 may be designed with an axial
length (e.g., width 175) such that at least some portion of the discourager tooth land
75 will be substantially directly radially underneath the non-rotating land 76 during
any anticipated axial excursion of the rotor shaft 26. Opposite the discourager tooth
may be a land 76 defining a radial design gap 77 between the surface 75 and the land
76. The discourager tooth 74 increases velocity of pressurized air passing adjacent
the upper tooth surface 75 and maintains the air at that higher velocity for a longer
duration of time than previous designs, resulting in an increase in impulse on oil
particles that may have leaked through the oil seal 68. Additionally the wide
discourager tooth 74 may compensate for axial excursions to minimize pressure loss
and maintain a more consistent pressure at the oil seal 68 during such excursions.
In some example embodiments, a ratio of discourager tooth width 175 to gap
width 78 may be greater than about 0.5. In some example embodiments, a ratio of
discourager tooth width 175 to gap width 78 may be greater than about 1.0. In some
example embodiments, a ratio of discourager tooth width 175 to gap width 78 may be
greater than about 4.0.
While multiple inventive embodiments have been described and illustrated
herein, those of ordinary skill in the art will readily envision a variety of other means
and/or structures for performing the function and/or obtaining the results and/or one
or more of the advantages described herein, and each of such variations and/or
modifications is deemed to be within the scope of the invent of embodiments
described herein. More generally, those skilled in the art will readily appreciate that
all parameters, dimensions, materials, and configurations described herein are meant
to be exemplary and that the actual parameters, dimensions, materials, and/or
configurations will depend upon the specific application or applications for which the
inventive teachings is/are used. Those skilled in the art will recognize, or be able to
ascertain using no more than routine experimentation, many equivalents to the
specific inventive embodiments described herein. It is, therefore, to be imderstood
that the foregoing embodiments are presented by way of example only and that,
within the scope of the appended claims and equivalents thereto, inventive
embodiments may be practiced otherwise than as specifically described and claimed.
14
Inventive embodiments of the present disclosure are directed to each individual
feature, system, article, material, kit, and/or method described herein. In addition, any
combination of two or more such features, systems, articles, materials, kits, and/or
methods, if such features, systems, articles, materials, kits, and/or methods are not
mutually inconsistent, is included within the inventive scope of the present disclosure.
Examples are used to disclose the embodiments, including the best mode, and
also to enable any person skilled in the art to practice the apparatus and/or method,
including making and using any devices or systems and performing any incorporated
methods. These examples are not intended to be exhaustive or to limit the disclosure
to the precise steps and/or forms disclosed, and many modifications and variations are
possible in light of the above teaching. Features described herein may be combined in
any combination. Steps of a method described herein may be performed in any
sequence that is physically possible.
All definitions, as defined and used herein, should be understood to control
over dictionary definitions, definitions in documents incorporated by reference,
and/or ordinary meanings of the defmed terms. The indefmite articles "a" and "an,"
as used herein in the specification and in the claims, unless clearly indicated to the
contrary, should be understood to mean "at least one." The phrase "and/or," as used
herein in the specification and in the claims, should be understood to mean "either or
both" of the elements so conjoined, i.e., elements that are conjunctively present in
some cases and disjunctively present in other cases.
It should also be understood that, unless clearly indicated to the contrary, in
any methods claimed herein that include more than one step or act, the order of the
steps or acts of the method is not necessarily limited to the order in which the steps or
acts of the method are recited.
In the claims, as well as in the specification above, all transitional phrases such
as "comprising," "including," "carrying," "having," "containing," "involving,"
"holding," "composed of," and the like are to be understood to be open-ended, i.e., to
mean including but not limited to. Only the transitional phrases "consisting o f and
"consisting essentially of shall be closed or semi-closed transitional phrases,
respectively, as set forth in the United States Patent Office Manual of Patent
Examining Procedures, Section 2111.03.
15
This written description uses examples to disclose the invention, including the
best mode, and also to enable any person skilled in the art to practice the invention,
including making and using any devices or systems and performing any incorporated
methods. The patentable scope of the invention is defined by the claims, and may
include other examples that occur to those skilled in fee art. Such other examples are
intended to be wifein the scope of the claims if they have structural elements that do
not differ from the literal language of the claims, or if they include equivalent
structural elements with insubstantial differences from the literal languages of the
claims.
16

We Claim:
1. An oil sump seal pressurization apparatus for a turbine engine, the oil sump seal
pressurization apparatus comprising:
a non-rotating oil sump housing a bearing, the bearing supporting a rotatable
shaft;
an oil seal at least partially isolating an interior of the oil sump, the oil seal
operatively acting between a non-rotating structural member of the sump and the
rotatable shaft;
a passage arranged to supply pressiuization air to an outward side of the oil
seal with respect to the oil sump;
a drain arranged to allow draining of oil and venting of at least some of the
pressurization air, the drain being positioned axially between the passage and the oil
seal;
a discourager tooth disposed on the shaft and extending radially outward
towards a non-rotating land, the land being disposed axially between the passage and
the drain, the discourager tooth being spaced apart from the land in a generally radial
direction by a gap having a width, the discourager tooth including an upper surface
having a width; and
a first adjacent tooth disposed on the shaft and extending radially outward
from the shaft, the fu-st adjacent tooth having a width;
wherein the discourager tooth width is at least about 1.5 times the width of the
first adjacent tooth.
2. The oil sump seal pressurization apparatus of claim 1, wherein the discourager
tooth width is at least about 2.0 times the width of the first adjacent tooth.
3. The oil sump seal pressiuization apparatus of claim 1, wherein the discourager
tooth width is at least about 2.5 times the width of the first adjacent tooth.
4. The oil sxraip seal pressurization apparatus of claim 1,
fiuther comprising a second adjacent tooth disposed on an axially opposite
side of the discourager tooth;
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wherein the discourager tooth width is at least about 1.5 times the width of the
first adjacent tooth and the discourager tooth width is at least about 1.5 times a width
of the second adjacent tooth.
5. The oil sump seal pressurization apparatus of claim 1,
further comprising a second adjacent tooth disposed on an axially opposite
side of the discourager tooth;
wherein the discourager tooth width is at least about 2.0 times the width of the
first adjacent tooth and the discourager tooth width is at least about 2.0 times a width
of the second adjacent tooth.
6. The oil sump seal pressurization apparatus of claim 1,
ftuther comprising a second adjacent tooth disposed on an axially opposite
side of the discourager tooth;
wherein the discourager tooth width is at least about 2.5 times the width of the
first adjacent tooth and the discourager tooth width is at least about 2.5 times a width
of the second adjacent tooth.
7. The oil sump seal pressurization apparatus of claim 1, wherein a ratio of
discourager tooth width to gap width is greater than about 0.5.
8. The oil sump seal pressurization apparatus of claim 1, wherein the ratio of
discourager tooth width to gap width is greater than about 1.0.
9. The oil sump seal pressurization apparatus of claim 1, wherein the ratio of
discourager tooth width to gap width is greater than about 4.0.
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10. An oil sump seal pressurization apparatus for a turbine engine, the oil sump seal
pressxuization apparatus comprising:
a non-rotating oil sump housing a bearing, the bearing supporting a rotatable
shaft;
an oil seal at least partially isolating an interior of tiie oil sump, the oil seal
operatively acting between a non-rotating structural member of the sump and the
rotatable shaft;
a passage arranged to supply pressurization air to an outward side of the oil
seal with respect to the oil sump;
a drain arranged to allow draining of oil and venting of at least some of the
pressurization air, the drain being positioned axially between the passage and the oil
seal; and
a discourager tooth disposed on the shaft and extending radially outward
towards a non-rotating land, the land being disposed axially between the passage and
the drain, the discourager tooth being spaced apart from the land in a generally radial
direction by a gap having a width, the discourager tooth including an upper surface
having a width;
wherein a ratio of discourager tooth width to gap width is greater than about
0.5.
11. The oil sump seal pressurization apparatus of claim 10, wherein the ratio of
discourager tooth width to gap width is greater than about 1.0.
12. The oil sirnip seal pressurization apparatus of claim 10, wherein the ratio of
discourager tooth width to gap width is greater than about 4.0.
13. The oil sump seal pressurization apparatus of claim 10,
further comprising a first adjacent tooth disposed on the shaft and extending
radially outward from the shaft;
wherein the discourager tooth width is at least about 1.5 times a width of the
first adjacent tooth.
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14. The oil sump seal pressurization apparatus of claim 13,
further comprising a second adjacent tooth disposed on an axially opposite
side of the discourager tooth;
wherein the discourager tooth width is at least about 1.5 times the width of the
first adjacent tooth and the discourager tooth width is at least about 1.5 tunes a width
of the second adj acent tooth.
15. The oil sump seal pressurization apparatus of claim 10,
further comprising a first adjacent tooth disposed on the shaft and extending
radially outward from the shaft;
wherein the discourager tooth width is at least about 2.0 times the width of the
first adjacent tooth.
16. The oil sump seal pressurization apparatus of claim 15,
further comprising a second adjacent tooth disposed on an axially opposite
side of the discourager tooth;
wherein the discourager tooth width is at least about 2.0 times the width of the
first adjacent tooth and the discourager tooth width is at least about 2.0 times a width
of the second adjacent tooth.
17. The oil sump seal pressurization apparatus of claim 10,
further comprising a first adjacent tootii disposed on the shaft and extending
radially outward from the shaft;
wherein the discourager tooth width is at least about 2.5 times the width of the
first adjacent tooth.
18. The oil sump seal pressurization apparatus of claim 17,
further comprising a second adjacent tooth disposed on an axially opposite
side of the discourager tooth;
wherein the discourager tooth width is at least about 2.5 times the width of the
first adjacent tooth and the discourager tooth width is at least about 2.5 times a width
of the second adjacent tooth.
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19. An oil sump seal pressurization apparatus for a turbine engine, the oil sump seal
pressurization apparatus comprising;
a non-rotating oil simip housing a bearing, the bearing supporting a rotatable
shaft;
an oil seal at least partially isolating an interior of the oil sump, the oil seal
operatively acting between a non-rotating structural member of the sump and the
rotatable shaft;
a passage arranged to supply pressurization air to an outward side of the oil
seal with respect to the oil sump;
a sump pressurization cavity disposed at least partially around the oil sump,
the sump pressurization cavity comprising a volume arranged to supply the
pressurization air to the passage;
a non-rotatable windage shield disposed within the sump pressurization cavity
between the volume and a rotatable arm disposed on the shaft;
a pressurization tooth fluidicly interposing the passage and the rotatable arm,
the pressurization tooth restricting flow of the pressurization air from the passage
towards the rotatable arm;
a drain arranged to allow draining of oil and venting of at least some of the
pressurization air, the drain being positioned axially between the passage and the oil
seal; and
a discoiirager tooth disposed on the shaft and extendmg radially outward
towards a non-rotating land, the land being disposed axially between the passage and
the drain, the discourager tooth being spaced apart firom the land in a generally radial
direction by a gap having a width, the discourager tooth including an upper surface
having a width.
20. The oil simip seal pressurization apparatus of claim 19, wherein the
pressurization tooth extends radially outwardly from the shaft generally towards the
windage shield.