BACKGROUND OF THE INVENTION
The present invention relates generally to aspirating face seals for rotor and
stator assemblies and, more particularly, to rotatable and non-rotatable gas
bearing face surfaces of aspirating face seals with pull off springs to retract the
non-rotatable gas bearing face surface away from the rotatable gas bearing face
surface during periods of low pressure differentials across the seal.
Aspirating face seals are used to minimize leakage through a gap between two
components and from a higher pressure area to a lower pressure area. Such
seals have been disclosed for use in rotating machinery, including, but not
I mited to, turbomachinery such as gas turbine engines used for power
generation and for aircraft and marine propulsion. Aspirating face seals are
designed to minimize leakage of a fluid such compressed air or combustion gases
between a rotor and a stator in gas turbine engines.
Conventional aspirating face seals typically have the rotor configured as
oppositely facing rotatable and non-rotatable seal elements, with the rotatable
seal element either being attached to, or being a monolithic portion of the rotor.
Such seals typically have the non-rotatable seal element configured being axially
movably attached to a portion of the stator. The rotatable and non-rotatable seal
elements are generally annular, generally perpendicular to the longitudinal axis
0f the rotor, generally opposing, axially spaced apart, and proximate each other.
Typically, the first rotatable and non-rotatable elements together define a radially
extending air bearing and a radially extending air dam positioned radially inward
01 the air bearing. An air bearing surface of the first element and an air dam

surface of the first element generally lie in the same plane. The air bearing
surface of the second element has a hole which is an outlet for a first
oassageway connecting the hole with air from a higher pressure side of the seal.
The stator has a second passageway which carries air, which has passed the air
Jam from the higher pressure side of the seal, to a lower pressure side of the
seal. Known seal designs have also included an aspirator tooth extending from
!:he stator axially across, and radially inward of, the air dam, with the aspirator
r.ooth having a tip spaced apart from and proximate the rotor. It is also important
o note that aspirating face seal technology uses phrases such as "air bearing",
air dam", and "air flow", wherein it is understood that the word "air" is used to
describe the working fluid of the seal. The working fluid of an aspirating face seal
can include, without limitation, compressed air, combustion gases, and/or steam.
Reference may be had to U.S. Pat. Nos. 5,311,734 and 5,975,537 for more
details on aspirating face seals and their operation.
Many aspirating face seals use multiple coil springs positioned circumferentially
iiround a portion of the stator for urging the non-rotatable seal element and its
iion-rotatable gas bearing surface away from the rotatable seal element and its
lotatable gas bearing surface when the engine is not running or when the
pressure differential across the aspirating seal is low. The multiple spring concept
includes many non-axisymetric parts which are exposed to the severe operating
(environment of a gas turbine engine. This includes significant dust which at high
velocity can quickly erode away the material of interrupted features like coil
springs. Some seals do not use springs and may allow rubbing of the rotor and
stator elements each time the engine is started causing premature part wear out.
[t is important to note that an aspirating face seal is a non-contacting seal in that
:he first and second parts of the seal are not suppose to touch but could for
5hort periods of time during which they experience what are known as rubs.
Aspirating face seals generate significant heat and/or scratch rotor surfaces
lA/hen seal rubs occur. It is, thus, desirable to minimize heat input into th3
rotating component and maintain a smooth surface flush. Excessive heat input
into the rotor component can result in material degradation which in turn can
lead to premature component crack initiation. A rough surface finish could result
in excessive seal leakage and create a stress riser, which could also cause
premature component crack initiation.
BRIEF DESCRIPTION OF THE INVENTION
A gas turbine engine aspirating face seal includes a rotatable engine member
and a non-rotatable engine member and a leakage path therebetween. An
annular generally planar non-rotatable gas bearing face surface is operably
associated with the non-rotatable engine member and an annular generally
planar rotatable gas bearing face surface is operably associated with the
rotatable engine member. The non-rotatable and rotatable gas bearing face
surfaces is circumscribed about and generally perpendicular to a centerline axis.
A substantially fully annular pull off biasing means is operably disposed for
urging the non-rotatable gas bearing face surface axially away from the rotatable
gas bearing face surface and circumscribed about the centerline axis. The pull off
biasing means may be at least one wave spring or one bellville washer. The non-
rotatable gas bearing face surface may be on a face seal ring mounted on a
translatable cylindrical piston which is axially movable and supported by the non-

rotatable engine member. The spring chamber may be formed in part by radially
extending static and axially movable flanges attached to a face seal support
structure and the translatable cylindrical piston respectively, wherein the face
seal support structure is supported by the non-rotatable engine member. The
rotatable engine member may be a rotor disk or, in a more particular
embodiment, the rotatable engine member is a side plate mounted on a rotor
disk and the non-rotatable gas bearing face surface is on a face seal ring
mounted on a translatable cylindrical piston which is axially movable and
supported by the non-rotatable engine member.
The seal may further include an auxiliary seal having a restrictor tooth radially
spaced apart: from and proximate to a seal land disposed between the rotatable
engine member and non-rotatable engine member. More particularly, the seal
may further include an auxiliary seal disposed across the leakage path radially
inwardly of the gas bearing face surfaces. The auxiliary seal may include an
annular restrictor tooth radially spaced apart from and proximate to an annular
seal land having an annular auxiliary seal surface circumscribed around the
engine centerline axis.
The seal may include radially inner and outer tooth rings axially extending away
from a first one of the gas bearing face surfaces across the leakage path and
towards a second one of the gas bearing face surfaces. An annular plenum is
located between the inner and outer tooth rings and a portion of the first gas
bearing face surface between the inner and outer tooth rings. Alternatively, the
seal may include a primary restrictor dam radially spaced apart from the non-
rotatable gas bearing face surface by an annular vent channel.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
FIG. 1 is a cross-sectional view illustration of a portion of an exemplary gas
turbine engine high pressure turbine and an aspirating gas bearing face seal with
axially extending teeth and a first exemplary embodiment of a one piece annular
pull off wave spring.
FIG. 2 is a perspective view illustration of a single wrap wave spring in FIG. 1.
FIG. 3 is a cross-sectional view illustration of a portion of an exemplary gas
turbine engine high pressure turbine and a second exemplary embodiment of a
gas bearing face seal with rotatable axially extending teeth.
FIG. 4 is a perspective view illustration of double wrap wave spring.
PIG. 5 is a cross-sectional view illustration of a portion of an exemplary gas
Dearing face seal as illustrated in FIG. 1 without axially extending teeth.
=IG. 6 is a cross-sectional view illustration of the aspirating gas bearing face seal
with a pull off bellville washer.
DETAILED DESCRIPTION OF THE INVENTION
llustrated in FIG. 1 is a portion of a gas turbine engine including a combustor 10
md a high pressure turbine 14 circumscribed around an engine centerline axis
l6. The high pressure turbine 14 includes a static turbine nozzle 18 and a
rotatable turbine stage 22 having coolable turbine blades 24 mounted on a rim
26 of a rotor disk 27 of the turbine stage 22. A portion of high pressure
compressor discharge air 20 not burned in a combustor of the engine is directed
from a relatively stationary inducer 29 to air cooling passages 32 In the rotatable
'otor disk 27 for cooling blades 24. The cooling passages 32 are axlally and
:lrcumferentlally bounded by a side plate 34 which also helps retain the blades
M in slots 36 in the rim 26 of the rotor disk 27. Compressor discharge air 20 Is
Jirected by the inducer 29 across a high pressure region 48 through apertures 33
n the side plate 34 to the air cooling passages 32.
i\n aspirating face seal 40 is used to restrict leakage of the high pressure
compressor discharge air 20 from the relatively high pressure region 48 to a
relatively low pressure region 46 at the juncture 49 between an rotatable enginj
riember exemplified by the rotor disk 27 and a non-rotatable engine member
scructure 58, The non-rotatable engine 58 depends from the turbine nozzle 18
and supports the Inducer 29. The face seal 40 Includes a leakage path 45
between rotatable and non-rotatable engine members and between a rotatable
aid non-rotatable gas bearing face surfaces 62 and 68 of the seal 40. The
rotatable and non-rotatable gas bearing face surfaces 62 and 68 are
ci'cumscrlbed around and generally perpendicular to the engine centerline axis
1 j. Non-rotatable Is defined as not rotating with the rotor disk 27 or other parts
ot an engine rotor during engine operation.
Illustrated in FIG. 1 is a first exemplary embodiment of the face seal 40 of the
present invention having a substantially fully annular pull off biasing means 82
cli cumscribed about the centerline axis 16 and operably disposed for urging the
non-rotatable gas bearing face surface 68 axially away from the rotatable gas
bearing face surface 62 of tlie seal 40 when the engine is not running and/or
when the pressures in the high and low pressure regions 48 and 46 are
substantially equal. The term pull off is used because the biasing means 82 is
used for urging the non-rotatable gas bearing face surface 68 away from the
rotatable gas bearing face surface 62.
The annular pull off biasing means 82 is illustrated in FIG. 1 as a pull off wave
spring 84 (also known as a cockle spring) disposed within a continuous annular
spring chamber 85 formed in part between radially extending static and axially
movable flanges 86 and 87 attached to the face seal support structure 52 and a
translatable cylindrical piston 88 respectively. The wave spring 84 may be a
single wrap wave spring as illustrated In FIG. 2 or a multiple wrap wave spring as
illustrated by a double wrap wave spring 91 in FIG. 4. Other alternative annular
pull off biasing means 82 include, but are not restricted to, wave or wavy
^A/ashers and bellville washers 93 which is illustrated in FIG. 6. IMore than one
spring or washer may be disposed in the spring chamber 85. The substantially
fully annular pull off biasing means 82 uses one or two springs or their
equivalent that are unitary or one piece as opposed to the use of the multiple
spring coil spring design that has many more parts both springs and coil spring
:hambers. The present invention has less parts, is therefore cheaper to
:onstruct, and is less susceptible to erosion due to dust at a high velocity.
The face seal 40 is designed to restrict leakage of the high pressure compressor
discharge air 20 through the leakage path 45 from the relatively high pressure
'egion 48 to the relatively low pressure region 46 at the juncture 49 between the
'otatable turbine stage 22 and the non-rotatable engine member 58. Tlie
exemplary seal 40 illustrated in FIG. 1 has non-rotatable annular radially inner
and outer axially extending tooth rings 42 and 44 extend axially away from the
non-rotatable gas bearing face surface 68 towards the rotatable gas bearing face
surface 62 on the side plate 34. In alternate embodiments, the annular radially
nner and outer axially extending tooth rings 42 and 44 may be rotatable and
extend axially away from the rotatable gas bearing face surface 62 towards the
lon-rotatable gas bearing face surface 68.
\ face seal ring 60 is mounted on the non-rotatable axially translatable cylindrical
oiston 88 which is axially movably supported on a non-rotatable face seal
support structure 52 attached to the non-rotatable engine member. The face
seal support structure 52 is fixed with respect to and supported by the non-
¦otatable engine member 58. Circumferentially spaced apart guide and support
oins 130 extend aftwardly from the face seal ring 60 through bushings 132
disposed in pin receiving holes 134 extending through guide and support pin
'langes 138 mounted on the face seal support structure 52 forming a guide and
support assembly. The guide and support assembly helps to radially support and
axially guide the face seal ring 60.
The radially inner and outer axially extending tooth rings 42 and 44 are mounted
Dn the face seal ring 60 and extend radially outward from the axially facing
generally planar non-rotatable gas bearing face surface 68 towards the axially
'acing generally planar rotatable substantially planar gas bearing face surface 62.
The face seal ring 60 is supported for axial movement with respect to the
¦otatable gas bearing face surface 62 which is on the side plate 34 that is
Tiounted to the rotor disk 27. The radially inner and outer tooth rings 42 and 44
Drovide for low heat input into the rotatable component which is exemplified
nerein as the side plate 34 and the rotor disk 27 to which it is mounted. The
'adially inner and outer tooth rings 42 and 44 help maintain a smooth rotor
surface finish which is exemplified herein as the rotatable gas bearing face
surface 62.
An annular plenum 69 is bounded by the inner and outer tooth rings 42 and 44
and the non-rotatable gas bearing face surface 68 radially extending between
the inner and outer tooth rings 42 and 44. The inner and outer tooth rings 42
and 44 extend axially towards the rotatable gas bearing face surface 62 on the
side plate 34 and have pointed ends 66 proximate to the rotatable gas bearing
face surface 62. A plurality of circumferentially spaced apart vent passages 93
through the face seal ring 60 provide pressure communication between the
plenum 69 and low pressure region 46. The vent passages 96 vent the plenum
69 with low pressure air from the low pressure region 46 therein during engine
operation when there is a substantial pressure differential between high and low
pressure regions 48 and 46. An axial gap G is defined between the non-rotatable
gas bearing face surface 68 and the rotatable gas bearing face surface 62.
An annular auxiliary seal 73 is also used to restrict airflow across the leakage
path 45 and to create sufficient pressure, when the engine is operating, to urge
the face seal ring 60 towards the rotatable gas bearing face surface 62. The
auxiliary seal 73 includes an annular restrictor tooth 74 extending radially across
the leakage path 45 towards an annular seal land 80 having an annular auxiliary
seal surface 78. A radial gap H is defined between the annular restrictor tooth 74
and the auxiliary seal surface 78. The restrictor tooth 74 is radially spaced apart
from and proximate the annular seal land 80. The annular restrictor tooth 74 and
annular seal land 80 are circumscribed around the engine centerline axis 16. In
the exemplary embodiment of the invention illustrated in FIG. 1, the restrictor
tooth 74 is attached to the rotatable side plate 34 and the seal land 80 having
the auxiliary seal surface 78 is attached to the face seal ring 60.
The face seal ring 60 is designed to translate between axial retracted and sealinq
positions RP and SP respectively as measured at the non-rotatable gas bearing
face surface 68, denoted by arrows marked accordingly, as a result of forces
acting on the face seal ring 60. The face seal ring 60 is illustrated in its sealing
position in the FIGS. The forces are the result of pressures in the relatively low
and high pressure regions 46 and 48 acting on surfaces and spring forces of the
biasing or biasing means 82. When the engine is running and the face seal ring
60 is in the sealing position SP and there is an operational clearance C between
the pointed ends 66 of the inner and outer tooth rings 42 and 44 and the
rotatable gas bearing face surface 62. In one exemplary embodiment of the
invention, when the face seal ring 60 in the sealing position SP, the axial gap G is
about 25 mils (0.025 inches), the radial gap H is about 100-150 mils (0.1-0.15
inches), and the operational clearance C is about 1-8 mils (0.001-0.008 inches).
In such an exemplary embodiment, a radius midway between the inner and
outer tooth rings 42 and 44 to the engine centerline axis 16 may be about 10
inches.
The face seals of the present invention avoid significant amounts of heating and
scratching of the rotor surfaces when seal rubs occur. Thus, reducing heat input
into the rotating components and maintaining a smootii surface finisln of tlie
rotating seal surface. This reduces the possibility of material degradation and
premature component crack initiation. A coating could be applied to the inner
and outer tooth rings 42 and 44, also referred to as rotor axial seal teeth, to
further minimize heat input into the rotor part, exemplified herein as the side
plate 34 and the rotor disk 27 to which it is mounted. Another coating could be
applied to the static part to minims heat generation and protect the parent
material of the static part from scratches.
During low or no power conditions the face seal ring 60 and the inner and outer
tooth rings 42 and 44 are biased away from the rotatable gas bearing face
surface 62 by the biasing means 82. During higher power operation, the
restrictor tooth 74 restricts the discharge air 20 flowing from the relatively high
pressure region 48 to the relatively low pressure region 46 thereby causing a
pressure differential between high and low pressure regions 48 and 46. The
pressure differential between high and low pressure regions 48 and 46 acts on
the face seal ring 60 and urges the face seal ring 60 and the inner and outer
tooth rings 42 and 44 and tooth toward the rotatable gas bearing face surface
62.
A portion of the high pressure discharge air 20 is supplied to a gas bearing space
100, which includes the annular plenum 69, between the face seal ring 60 and
the rotatable gas bearing face surface 62 through the vent passages 96 in the
face sealing ring to establish a predetermined gas bearing face clearance.
Pressure forces developed in the gas bearing space 100 oppose further motion of
the face seal ring 60 and the inner and outer tooth rings 42 and 44 toward the
'Otatable gas bearing face surface 62. Accelerations and otiier motion of the face
seal ring 60 and the inner and outer tooth rings 42 and 44 towards the rotatable
gas bearing face surface 62 increases the pressure forces in the gas bearing
jpace 100, thereby urging the face seal ring away from the rotatable gas bearing
ace surface to maintain the predetermined clearance.
As the engine is started, the compressor discharge pressure rises and the
pressure in the high pressure region 48 begins to rise because the restrictor
100th 74 restricts the discharge air 20 flowing from the relatively high pressure
legion 48 to the relatively low pressure region 46. The pressure differential
hetween the low and high pressure regions 46 and 48 results in a closing
pressure force acting on face seal ring 60. The pressure force acts against a
spring force from the biasing means 82 to urge face seal ring 60 and the inner
iind outer tooth rings 42 and 44 toward the rotatable gas bearing face surface
(2.
hs face seal ring 60 reaches the sealing position SP, the axial gap G becomes
nuch smaller than the radial gap H, the pressure drop across the restrictor tooth
/ 4 is insubstantial and airflow caused by the pressure drop between the low and
Mgh pressure regions 46 and 48 occurs substantially across gap between the
f 3ce seal ring 60 and the inner and outer tooth rings 42 and 44 and the rotatable
gas bearing face surface 62. Thus, gas bearing forces are developed at the non-
r )tatable gas bearing face surface 68 and the rotatable gas bearing face surface
62 which, acting with the spring force, balance the closing force and maintain
t le operational clearance C between the pointed ends 66 of the inner and outer
ti)oth rings 42 and 44 and the rotatable gas bearing face surface 62 at a
predetermined size.

A secondary seal means, such as a circumferentially extending split piston ring
secondary seal 120, is provided to allow the face seal ring 60 to translate axially
in response to the motions of the rotating surface on the rotor. The piston ring
secondary seal 120 is urged radially inwardly by spring means, such as second
coil springs 76, against a radially inwardly facing annular inner surface 118 of the
face seal ring 60. A circumferentially extending secondary seal dam 122 on the
oiston ring secondary seal 120 is urged into radial sealing engagement with the
nner surface 118. The piston ring secondary seal 120 is urged axially by a third
spring means, such as by a plurality of circumferentially spaced third coil springs
L24, into engagement with an axially facing substantially planar sealing surface
L26 on the face seal support structure 52.
Ilustrated in FIG. 3 is a second exemplary embodiment of a face seal 40 of the
present invention having axially extending annular radially inner and outer
otatable tooth rings 142 and 144 mounted on the side plate 34 which is
-attached to the rotatable turbine stage 22. The rotatable tooth rings 142 and 14}
iire engagable with a substantially planar non-rotatable gas bearing face surface
68. The face seal ring 60 includes the non-rotatable gas bearing face surface
: 68 and is mounted on the translatable cylindrical piston 88 which is axially
movably supported on the non-rotatable face seal support structure 52. The
iiner and outer rotatable tooth rings 142 and 144 extend axially from the
rotatable gas bearing face surface 162 towards and have teeth which are
proximate the non-rotatable gas bearing face surface 168. The face seal ring 60
(ontaining the non-rotatable gas bearing face surface 168 is supported for axial
novement with respect to the inner and outer rotatable tooth rings 142 and 144
c n the side plate 34 which is attached to the rotor disk 27. The annular restrictor
tooth 74 is attached to the face seal ring 60 and the auxiliary seal surface 78 and
the seal land 80 are attached to the rotatable side plate 34.
Illustrated in FIG. 5 is a third exemplary embodinnent of an aspirating face seal
180 of the present invention. The face seal ring 60 includes a primary restrictor
dam 184 radially spaced apart from a substantially planar non-rotatable gas
bearing face surface 188 by an annular vent channel 190. The segmented
channel resembles circumferentially distributed pockets. The non-rotatable gas
bearing face surface 188 is proximate to a rotatable gas bearing face surface 194
and the seal 180 is designed to operate with an operational clearance C
therebetween during engine operation. An annular deflector 200 extends radialh/
from the rotatable gas bearing face surface 194 towards the annular vent
channel 190 and may extend slightly into the vent channel. The deflector 200
prevents a strong airflow or jet from developing across the rotatable gas bearing
face surface 194 due to a large differential pressure between the relatively low
and high pressure regions 46 and 48. Such a high speed flow or jet could
produce a sufficient pressure drop so as to cause the non-rotatable gas bearing
^ace surface 188 to be sucked towards and into the rotatable gas bearing face
surface 194.
(A/hile there have been described herein what are considered to be preferred and
exemplary embodiments of the present invention, other modifications of the
nvention shall be apparent to those skilled in the art from the teachings herein
and, it is therefore, desired to be secured in the appended claims all such
Tiodifications as fall within the true spirit and scope of the invention. Accordingly,
vvhat is desired to be secured by Letters Patent of the United States is the
nvention as defined and differentiated in the following claims.

WE CLAIM
1. A gas turbine engine aspirating face seal comprising:
a rotatable engine member and a non-rotatable engine member and a
leakage path therebetween,
an annular generally planar non-rotatable gas bearing face surface
operably associated with said non-rotatable engine member,
an annular generally planar rotatable gas bearing face surface operably
associated with said rotatable engine member,
said non-rotatable and rotatable gas bearing face surfaces being
circumscribed about and generally perpendicular to a centerline axis,
a substantially fully annular pull off biasing means operably disposed for
urging said non-rotatable gas bearing face surface axially away from said
rotatable gas bearing face surface and circumscribed about said centerline
axis, and
said pull off biasing means including at least one wave spring or one
belleville washer circumscribed about said centerline axis.
2. A seal as claimed in claim 1 wherein non-rotatable gas bearing face
surface is on a face seal ring mounted on a translatable cylindrical piston
which is axially movable and supported by said non-rotatable engine
member.

3. A seal as claimed in claim 2 wherein said at least one wave spring or one
belleville washer is disposed within a continuous annular spring chamber
formed in part by radially extending static and axially movable flanges
attached to a face seal support structure and said translatable cylindrical
piston respectively wherein said face seal support structure is supported
by said non-rotatable engine member.
4. A gas turbine engine aspirating face seal comprising:
a rotatable engine member and a non-rotatable engine member and a
leakage path therebetween,
an annular generally planar non-rotatable gas bearing face surface
operably associated with said non-rotatable engine member,
an annular generally planar rotatable gas bearing face surface operably
associated with said rotatable engine member,
said non-rotatable and rotatable gas bearing face surfaces being
circumscribed about and generally perpendicular to a centerline axis,
a substantially fully annular pull off biasing means operably disposed for
urging said non-rotatable gas bearing face surface axially away from said
rotatable gas bearing face surface and circumscribed about said centerline
axis, and
said rotatable engine member being a rotor dlsl< having turbine blades
mounted on a rim thereof.
5, A gas turbine engine aspirating face seal comprising:
a rotatable engine member and a non-rotatable engine member and a
leakage path therebetween,
an annular generally planar non-rotatable gas bearing face surface
operably associated with said non-rotatable engine member,
an annular generally planar rotatable gas bearing face surface operably
associated with said rotatable engine member,
said non-rotatable and rotatable gas bearing face surfaces being
circumscribed about and generally perpendicular to a centerline axis,
a substantially fully annular pull off biasing means operably disposed for
urging said non-rotatable gas bearing face surface axially away from said
rotatable gas bearing face surface and circumscribed about said centerline
axis, and
wherein said rotatable engine member is a side plate mounted on a rotor
disk and said non-rotatable gas bearing face surface is on a face seal ring
mounted on a translatable cylindrical piston which is axially movable and
supported by said non-rotatable engine member.
6. A seal as claimed In claim 5 wherein said pull off biasing means includes
at least one wave spring or one belleville washer.
7. A seal as claimed in claim 6 comprising an auxiliary seal having a restrictor
tooth radially spaced apart from and proximate to a seal land disposed
between said rotatable engine member and said non-rotatable engine
member.
8. A seal as claimed in claim 6 comprising an auxiliary seal disposed acoss
said leakage path radially inwardly of said gas bearing face surfaces, said
auxiliary seal comprising an annular restrictor tooth radially spaced apart
from and proximate to an annular seal land having an annular auxiliary
seal sutface circumscribed around said engine centerline axis.
9. A gas turbine engine aspirating face seal comprising:
a rotatable engine member and a non-rotatable engine member and a
leakage path therebetween,
an annular generally planar non-rotatable gas bearing face surface
operably associated with said non-rotatable engine member,
an annular generally planar rotatable gas bearing face surface operably
associated with said rotatable engine member,
said non-rotatable and rotatable gas bearing face surfaces being
circumscribed about and generally perpendicular to a centerline axis.
a substantially fully annular pull off biasing means operably disposed for
urging said non-rotatable gas bearing face surface axially away from said
rotatable gas bearing face surface and circumscribed about said centerline
axis,
radially inner and outer tooth rings axially extending away from a first one
of said gas bearing face surfaces across said leakage path and towards a
second one of said gas bearing face surfaces, and
an annular plenum located between said inner and outer tooth rings and a
portion of said first gas bearing face surface between said inner and outer
tooth rings.
10. A seal as claimed in claim 9 wherein said pull off biasing means includes
at least one wave spring or one belleville washer.
11. A seal as claimed in claim 10 wherein said non-rotatable gas bearing face
surface is on a face seal ring mounted on a translatable cylindrical piston
which is axially movable and supported by said non-rotatable engine
member.
12. A seal as claimed in claim 11 wherein said spring chamber is formed in
part by radially extending static and axially movable flanges attached to a
face seal support structure and said translatable cylindrical piston
respectively wherein said face seal support structure is supported by said
non-rotatable engine member.
13. A gas turbine engine aspirating face seal comprising:
a rotatable engine member and a non-rotatable engine member and a
leakage path therebetween,
an annular generally planar non-rotatable gas bearing face surface
operably associated with said non-rotatable engine member,
an annular generally planar rotatable gas bearing face surface operably
associated with said rotatable engine member,
said non-rotatable and rotatable gas bearing face surfaces being
circumscribed about and generally perpendicular to a centerline axis,
a substantially fully annular pull off biasing means operably disposed for
urging said non-rotatable gas bearing face surface axially away from said
rotatable gas bearing face surface and circumscribed about said centerline
axis, and
a primary restrictor darn radially spaced apart from said non-rotatable gas
bearing face surface by an annular vent channel,
14. A seal as claimed in claim 13 wherein said pull off biasing means includes
at least one wave spring or one belleville washer.
15. A seal as claimed in claim 14 wherein said non-rotatable gas bearing face
surface is on a face seal ring mounted on a translatable cylindrical piston
which is axially movable and supported by said non-rotatable engine
member.
16. A seal as claimed in claim 15 wherein said at least one wave spring or one
belleville washer is disposed within a continuous annular spring chamber
formed in part by radially extending static and axially movable flanges
attached to a face seal support structure and said translatable cylindrical
piston respectively wherein said face seal support structure is supported
by said non-rotatable engine member.
17. A seal as claimed in claim 16 comprising an auxiliary seal having a
restrictor tooth radially spaced apart from and proximate to a seal land
disposed between said rotatable engine member and said non-rotatable
engine member.
18. A seal as claimed in claim 16 comprising an auxiliary seal disposed across
said leakage path radially inwardly of said gas bearing face surfaces, said
auxiliar/ seal comprising an annular restrictor tooth radially spaced apart
from and proximate to an annular seal land having an annular auxiliary
seal surface circumscribed around said engine centerline axis.

This invention relates to a gas turbine engine aspirating face seal (40)
comprising; a rotatable engine member (28) and a non-rotatable engine member
(58) and a leakage path (45) therebetween, an annular generally planar non-
rotatable gas bearing face surface (68) operably associated with said non-
rotatable engine member (58), an annular generally planar rotatable gas bearing
face surface (62) operably associated with said rotatable engine member (28),
said non-rotatable and rotatable gas bearing face surfaces (68, 62) being
circumscribed about and generally perpendicular to a centerline axis (16. A
substantially fully annular pull off biasing means (82) operably disposed For
urging said non-rotatable gas bearing face surface (68) axially away from said
rotatable gas bearing face surface (62) and circumscribed about said centerline
axis (16).