U.S. patent application number 14/130511 was filed with the patent office on 2014-09-18 for circumferential seal with ceramic runner.
This patent application is currently assigned to Stein Seal Company. The applicant listed for this patent is Stein Seal Company. Invention is credited to Thurai Manik Vasagar.
Application Number | 20140265151 14/130511 |
Document ID | / |
Family ID | 51524091 |
Filed Date | 2014-09-18 |
United States Patent
Application |
20140265151 |
Kind Code |
A1 |
Vasagar; Thurai Manik |
September 18, 2014 |
Circumferential Seal with Ceramic Runner
Abstract
The disclosure describes a circumferential seal applicable to
turbine engines. The circumferential seal includes a ceramic
runner, an annular seal ring, at least one tolerance ring, and a
pair of sealing rings. The runner is circumscribed about a shaft or
a carrier within a recess along the shaft and is bounded by a
shoulder and a clamping ring. At least one non-sealing spring
mechanism is disposed between and directly contacts the shoulder
and the first end of the runner. A second end of the runner
directly contacts the clamping ring. In other embodiments, at least
one non-sealing spring mechanism is disposed between and directly
contacts the second end and the clamping ring and the first end
directly contacts the shoulder. An anti-rotation element is
attached to the clamping ring, carrier, or shaft and extends into a
slot or hole or slot along the runner. The spring(s) applies a
biasing force onto the runner toward the clamping ring or shoulder.
The annular seal ring is rotationally stationary and circumscribed
about the runner. The tolerance ring(s) directly contacts the
runner and the shaft. The runner is fixed to the shaft or carrier
via the tolerance ring(s), anti-rotation element, and spring(s) so
that the runner rotates with the shaft. The sealing rings directly
contact the runner and the shaft along the annular gap about the
tolerance ring(s).
Inventors: |
Vasagar; Thurai Manik;
(Hatfield, PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Stein Seal Company |
Kulpsville |
PA |
US |
|
|
Assignee: |
Stein Seal Company
Kulpsville
PA
|
Family ID: |
51524091 |
Appl. No.: |
14/130511 |
Filed: |
May 13, 2013 |
PCT Filed: |
May 13, 2013 |
PCT NO: |
PCT/US2013/040812 |
371 Date: |
January 2, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61789419 |
Mar 15, 2013 |
|
|
|
Current U.S.
Class: |
277/500 |
Current CPC
Class: |
F01D 11/003 20130101;
F01D 25/183 20130101; F05D 2300/20 20130101 |
Class at
Publication: |
277/500 |
International
Class: |
F01D 11/00 20060101
F01D011/00 |
Claims
1. A circumferential seal comprising: (a) a ceramic runner
circumscribed about a recess along a shaft, said recess bounded by
a shoulder and a clamping ring, a first annular gap disposed
between a first end of said ceramic runner and said shoulder, a
second end of said ceramic runner directly contacts said clamping
ring, an anti-rotation pin attached to said clamping ring and
extends into a slot along said ceramic runner, at least one
non-sealing spring mechanism disposed between and directly contacts
said shoulder and said first end along said first annular gap, said
at least one non-sealing spring mechanism applies a biasing force
onto said ceramic runner toward said clamping ring; (b) an annular
seal ring circumscribed about said ceramic runner and disposed
within a seal housing so that said annular seal ring is
rotationally stationary; (c) at least one tolerance ring directly
contacts said ceramic runner and said shaft along a second annular
gap between said ceramic runner and said shaft, said ceramic runner
fixed to said shaft via said at least one tolerance ring, said
anti-rotation pin, and said at least one non-sealing spring
mechanism so that said ceramic runner rotates with said shaft, said
at least one non-sealing spring mechanism expands and contracts in
response to expansion and contraction of said ceramic runner; and
(d) a pair of sealing rings directly contacts said ceramic runner
and said shaft between said pair of sealing rings.
2. The circumferential seal of claim 1, wherein said at least one
non-sealing spring mechanism is a wave spring.
3. The circumferential seal of claim 1, wherein said at least one
non-sealing spring mechanism is a compression spring.
4. The circumferential seal of claim 1, wherein said at least one
non-sealing spring mechanism is a plurality of compression springs
separately disposed about said first annular gap, each said
compression spring separately attached to said shoulder.
5. The circumferential seal of claim 1, wherein each said tolerance
ring and each said sealing ring separately disposed within an equal
number of annular grooves along said ceramic runner.
6. The circumferential seal of claim 1, wherein each said tolerance
ring and each said sealing ring separately disposed within an equal
number of annular grooves along said shaft.
7. The circumferential seal of claim 1, wherein said annular seal
ring forms a contact seal about said ceramic runner.
8. The circumferential seal of claim 1, wherein said annular seal
ring forms a non-contact seal about said ceramic runner.
9. The circumferential seal of claim 1, wherein at least one said
sealing ring is an O-ring, a spring-energized seal, or a
high-temperature metallic seal ring.
10. A circumferential seal comprising: (a) a ceramic runner
circumscribed about a recess along a shaft, said recess bounded by
a shoulder and a clamping ring, a first annular gap disposed
between a second end of said ceramic runner and said clamping ring,
a first end of said ceramic runner directly contacts said shoulder
along said shaft, an anti-rotation pin attached to said shoulder
and extends into a slot along said ceramic runner, at least one
non-sealing spring mechanism disposed between and directly contacts
said clamping ring and said second end along said first annular
gap, said at least one non-sealing spring mechanism applies a
biasing force onto said ceramic runner toward said shoulder; (b) an
annular seal ring circumscribed about said ceramic runner and
disposed within a seal housing so that said annular seal ring is
rotationally stationary; (c) at least one tolerance ring directly
contacts said ceramic runner and said shaft along a second annular
gap between said ceramic runner and said shaft, said ceramic runner
fixed to said shaft via said at least one tolerance ring, said
anti-rotation pin, and said at least one non-sealing spring
mechanism so that said ceramic runner rotates with said shaft, said
at least one non-sealing spring mechanism expands and contracts in
response to expansion and contraction of said ceramic runner; and
(d) a pair of sealing rings directly contacts said ceramic runner
and said shaft along said second annular gap, said at least one
tolerance ring disposed between said pair of sealing rings.
11. The circumferential seal of claim 10, wherein said at least one
non-sealing spring mechanism is a wave spring.
12. The circumferential seal of claim 10, wherein said at least one
non-sealing spring mechanism is a compression spring.
13. The circumferential seal of claim 10, wherein said at least one
non-sealing spring mechanism is a plurality of compression springs
separately disposed about said first annular gap, each said
compression spring separately attached to said clamping ring.
14. The circumferential seal of claim 10, wherein each said
tolerance ring and each said sealing ring separately disposed
within an equal number of annular grooves along said ceramic
runner.
15. The circumferential seal of claim 10, wherein each said
tolerance ring and each said sealing ring separately disposed
within an equal number of annular grooves along said shaft.
16. The circumferential seal of claim 10, wherein said annular seal
ring forms a contact seal about said ceramic runner.
17. The circumferential seal of claim 10, wherein said annular seal
ring forms a non-contact seal about said ceramic runner.
18. The circumferential seal of claim 10, wherein at least one said
sealing ring is an O-ring, a spring-energized seal, or a
high-temperature metallic seal ring.
19. A circumferential seal comprising: (a) a carrier disposed about
and directly contacts a shaft within a recess along said shaft,
said carrier rotatable with said shaft, said carrier having a
shoulder at one end; (b) a ceramic runner circumscribed about said
carrier, said ceramic runner disposed between said shoulder and a
clamping ring, a first annular gap disposed between a first end of
said ceramic runner and said shoulder, a second end of said ceramic
runner directly contacts said clamping ring, an anti-rotation key
attached to said clamping ring and extends into a slot along said
ceramic runner, at least one non-sealing spring mechanism directly
contacts said shoulder and said first end along said first annular
gap, said at least one non-sealing spring mechanism applies a
biasing force onto said ceramic runner toward said clamping ring;
(c) an annular seal ring circumscribed about said ceramic runner
and disposed within a seal housing so that said annular seal ring
is rotationally stationary; (d) at least one tolerance ring
directly contacts said ceramic runner and said carrier along a
second annular gap between said ceramic runner and said carrier,
said ceramic runner fixed to said carrier via said at least one
tolerance ring, said anti-rotation key, and said at least one
non-sealing spring mechanism so that said ceramic runner rotates
with said carrier, said at least one non-sealing spring mechanism
expands and contracts in response to expansion and contraction of
said ceramic runner; and (e) a pair of sealing rings directly
contacts said ceramic runner and said carrier along said second
annular gap, said at least one tolerance ring disposed between said
pair of sealing rings.
20. The circumferential seal of claim 19, wherein said at least one
non-sealing spring mechanism is a wave spring.
21. The circumferential seal of claim 19, wherein said at least one
non-sealing spring mechanism is a compression spring.
22. The circumferential seal of claim 19, wherein said at least one
non-sealing spring mechanism is a plurality of compression springs
separately disposed about said first annular gap, each said
compression spring separately attached to said shoulder.
23. The circumferential seal of claim 19, wherein each said
tolerance ring and each said sealing ring separately disposed
within an equal number of annular grooves along said carrier.
24. The circumferential seal of claim 19, wherein each said
tolerance ring and each said sealing ring separately disposed
within an equal number of annular grooves along said ceramic
runner.
25. The circumferential seal of claim 19, wherein said annular seal
ring forms a contact seal about said ceramic runner.
26. The circumferential seal of claim 19, wherein said annular seal
ring forms a non-contact seal about said ceramic runner.
27. The circumferential seal of claim 19, wherein at least one said
sealing ring is an O-ring, a spring-energized seal, or a
high-temperature metallic seal ring.
28. A circumferential seal comprising: (a) a carrier disposed about
and directly contacts a shaft within a recess along said shaft,
said carrier rotatable with said shaft, said carrier having a
shoulder at one end; (b) a ceramic runner circumscribed about said
carrier, said ceramic runner disposed between said shoulder and a
clamping ring, a first annular gap disposed between a second end of
said ceramic runner and said clamping ring, a first end of said
ceramic runner directly contacts said shoulder, an anti-rotation
key attached to said shoulder and extends into a slot along said
ceramic runner, at least one non-sealing spring mechanism directly
contacts said clamping ring and said second end along said first
annular gap, said at least one non-sealing spring mechanism applies
a biasing force onto said ceramic runner toward said shoulder; (c)
an annular seal ring circumscribed about said ceramic runner and
disposed within a seal housing so that said annular seal ring is
rotationally stationary; (d) at least one tolerance ring directly
contacts said ceramic runner and said carrier along a second
annular gap between said ceramic runner and said carrier, said
ceramic runner fixed to said carrier via said at least one
tolerance ring, said anti-rotation key, and said at least one
non-sealing spring mechanism so that said ceramic runner rotates
with said carrier, said at least one non-sealing spring mechanism
expands and contracts in response to expansion and contraction of
said ceramic runner; and (e) a pair of sealing rings directly
contacts said ceramic runner and said carrier along said second
annular gap, said at least one tolerance ring disposed between said
pair of sealing rings.
29. The circumferential seal of claim 28, wherein said at least one
non-sealing spring mechanism is a wave spring.
30. The circumferential seal of claim 28, wherein said at least one
non-sealing spring mechanism is a compression spring.
31. The circumferential seal of claim 28, wherein said at least one
non-sealing spring mechanism is a plurality of compression springs
separately disposed about said first annular gap, each said
compression spring separately attached to said clamping ring.
32. The circumferential seal of claim 28, wherein each said
tolerance ring and each said sealing ring separately disposed
within an equal number of annular grooves along said carrier.
33. The circumferential seal of claim 28, wherein each said
tolerance ring and each said sealing ring separately disposed
within an equal number of annular grooves along said ceramic
runner.
34. The circumferential seal of claim 28, wherein said annular seal
ring forms a contact seal about said ceramic runner.
35. The circumferential seal of claim 28, wherein said annular seal
ring forms a non-contact seal about said ceramic runner.
36. The circumferential seal of claim 28, wherein at least one said
sealing ring is an O-ring, a spring-energized seal, or a
high-temperature metallic seal ring.
37. A circumferential seal comprising: (a) a carrier disposed about
and directly contacts a shaft within a recess along said shaft,
said carrier rotatable with said shaft, said carrier having a
shoulder at one end; (b) a ceramic runner circumscribed about said
carrier, said ceramic runner disposed between said shoulder and a
clamping ring, a first annular gap disposed between a first end of
said ceramic runner and said shoulder, a second end of said ceramic
runner directly contacts said clamping ring, an anti-rotation screw
attached to said carrier and extends into a hole along said ceramic
runner, at least one non-sealing spring mechanism directly contacts
said shoulder and said first end along said first annular gap, said
at least one non-sealing spring mechanism applies a biasing force
onto said ceramic runner toward said clamping ring; (c) an annular
seal ring circumscribed about said ceramic runner and disposed
within a seal housing so that said annular seal ring is
rotationally stationary; (d) at least one tolerance ring directly
contacts said ceramic runner and said carrier along a second
annular gap between said ceramic runner and said carrier, said
ceramic runner fixed to said carrier via said at least one
tolerance ring, said anti-rotation screw, and said at least one
non-sealing spring mechanism so that said ceramic runner is
rotatable with said carrier, said at least one non-sealing spring
mechanism expands and contracts in response to expansion and
contraction of said ceramic runner; and (e) a pair of sealing
rings, at least one said sealing ring directly contacts said
ceramic runner and said carrier along said second annular gap, said
at least one tolerance ring and said anti-rotation screw disposed
between said pair of sealing rings.
38. The circumferential seal of claim 37, wherein said at least one
non-sealing spring mechanism is a wave spring.
39. The circumferential seal of claim 37, wherein said at least one
non-sealing spring mechanism is a compression spring.
40. The circumferential seal of claim 37, wherein said at least one
non-sealing spring mechanism is a plurality of compression springs
separately disposed about said first annular gap, each said
compression spring separately attached to said shoulder.
41. The circumferential seal of claim 37, wherein each said
tolerance ring and one said sealing ring separately disposed within
an equal number of annular grooves along said carrier and another
said sealing ring disposed within another said annular groove along
said clamping ring.
42. The circumferential seal of claim 37, wherein each said
tolerance ring and one said sealing ring separately disposed within
an equal number of annular grooves along said ceramic runner and
another said sealing ring disposed within another said annular
groove along said clamping ring.
43. The circumferential seal of claim 37, wherein said annular seal
ring forms a contact seal about said ceramic runner.
44. The circumferential seal of claim 37, wherein said annular seal
ring forms a non-contact seal about said ceramic runner.
45. The circumferential seal of claim 37, wherein at least one said
sealing ring is an O-ring, a spring-energized seal, or a
high-temperature metallic seal ring.
46. A circumferential seal comprising: (a) a carrier disposed about
and directly contacts a shaft within a recess along said shaft,
said carrier rotatable with said shaft, said carrier having a
shoulder at one end; (b) a ceramic runner circumscribed about said
carrier, said ceramic runner disposed between said shoulder and a
clamping ring, a first annular gap disposed between a second end of
said ceramic runner and said clamping ring, a first end of said
ceramic runner directly contacts said shoulder, an anti-rotation
screw attached to said carrier and extends into a hole along said
ceramic runner, at least one non-sealing spring mechanism directly
contacts said clamping ring and said second end along said first
annular gap, said at least one non-sealing spring mechanism applies
a biasing force onto said ceramic runner toward said shoulder; (c)
an annular seal ring circumscribed about said ceramic runner and
disposed within a seal housing so that said annular seal ring is
rotationally stationary; (d) at least one tolerance ring directly
contacts said ceramic runner and said carrier along a second
annular gap between said ceramic runner and said carrier, said
ceramic runner fixed to said carrier via said at least one
tolerance ring, said anti-rotation screw, and said at least one
non-sealing spring mechanism so that said ceramic runner is
rotatable with said carrier, said at least one non-sealing spring
mechanism expands and contracts in response to expansion and
contraction of said ceramic runner; and (e) a pair of sealing
rings, at least on said sealing ring directly contacts said ceramic
runner and said carrier along said second annular gap, said at
least one tolerance ring and said anti-rotation screw disposed
between said pair of sealing rings.
47. The circumferential seal of claim 46, wherein said at least one
non-sealing spring mechanism is a wave spring.
48. The circumferential seal of claim 46, wherein said at least one
non-sealing spring mechanism is a compression spring.
49. The circumferential seal of claim 46, wherein said at least one
non-sealing spring mechanism is a plurality of compression springs
separately disposed about said first annular gap, each said
compression spring separately attached to said clamping ring.
50. The circumferential seal of claim 46, wherein each said
tolerance ring and one said sealing ring separately disposed within
an equal number of annular grooves along said carrier and another
said sealing ring disposed within another said annular groove along
said clamping ring.
51. The circumferential seal of claim 46, wherein each said
tolerance ring and one said sealing ring separately disposed within
an equal number of annular grooves along said ceramic runner and
another said sealing ring disposed within another said annular
groove along said clamping ring.
52. The circumferential seal of claim 46, wherein said annular seal
ring forms a contact seal about said ceramic runner.
53. The circumferential seal of claim 46, wherein said annular seal
ring forms a non-contact seal about said ceramic runner.
54. The circumferential seal of claim 46, wherein at least one said
sealing ring is an O-ring, a spring-energized seal, or a
high-temperature metallic seal ring.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is based upon and claims priority from
Patent Cooperation Treaty Application No. PCT/US2013/040812 filed
May 13, 2013 which further claims priority from U.S. Provisional
Application No. 61/789,419 filed Mar. 15, 2013, both entitled
Circumferential Seal with Ceramic Runner. The subject matters of
the prior applications are incorporated in their entirety herein by
reference thereto.
FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT
[0002] None.
BACKGROUND OF THE INVENTION
[0003] 1. Field of the Invention
[0004] The invention generally relates to a sealing device for
turbine engines. Specifically, the invention is directed to a
circumferential seal disposed about a rotatable shaft wherein a
ceramic runner is attached to the shaft adjacent to a carbon
sealing ring.
[0005] 2. Background
[0006] Seal assemblies are used in gas turbine engines to prevent
or limit leakage of a fluid along the interface between a rotating
shaft and an otherwise fixed element.
[0007] By way of example, FIG. 1 shows a typical circumferential
seal 1 including a rotating component called a seal rotor 2 and a
non-rotating component called a seal stator 3. The seal rotor 2 is
made of metal, is mounted to a rotatable shaft 4, and has a
radially outward facing sealing surface 5. The seal stator 3
includes a ring 6 made of metal mounted to the housing 7 and a
sealing ring 8. The sealing ring 8 is made of carbon and includes
an inward facing sealing surface 10. The seal stator 3 and seal
rotor 2 are arranged so that the inward facing sealing surface 10
circumscribes the outward facing sealing surface 5. A small radial
gap 9 is maintained between the sealing ring 8 and seal rotor 2 to
avoid damage to the softer sealing ring 8.
[0008] A common problem associated with circumferential seals and
bushings occurs as a result of variation in the radial gap 9
between the sealing ring 8 and seal rotor 2. This variation is due
in part to the mechanical growth of the seal rotor 2 due to
centrifugal effects, but more significantly due to a disparity in
the thermal growth between the seal rotor 2, typically composed of
a material with a higher coefficient of thermal expansion, and the
sealing ring 8, typically composed of a material with a lower
coefficient of thermal expansion.
[0009] A variation in the radial gap 9 produces an undesirable
effect when it is too wide open or too narrow. If the radial gap 9
is too large, then the flow of fluid between the sealing ring 8 and
the seal rotor 2 increases so as to adversely affect pressures
within the high and low pressure sections of a turbine engine,
thereby reducing the performance and efficiency thereof. If the gap
is too small, then contact between the sealing ring 8 and seal
rotor 2 occurs and damage results to one or both components.
[0010] In U.S. Pat. No. 6,322,081, Ullah et al. describes a
circumferential seal with ceramic runner to address sealing
challenges associated with a seal system incorporating materials
with divergent thermal expansions.
[0011] Referring now to the FIG. 2, a section 11 of a gas turbine
engine is shown including a rotatable shaft 4 on which rotating
engine components, such as the radial compressor wheel 12, are
mounted. Circumscribing the rotatable shaft 4 is a stationary
housing 7. The stationary housing 7 is mounted atop a bearing 13
having an inner race 14 which is mounted on the rotatable shaft 4.
Disposed between the housing 7 and shaft 4 is a circumferential
seal 15. The circumferential seal 15 includes a seal stator 3
having a metal ring 6 mounted to the housing 7 and a carbon sealing
ring 8 mounted to its radial inward facing surface. The carbon
sealing ring 8 has a radially inward facing sealing surface 10.
[0012] The circumferential seal 15 also includes a sealing rotor
16. The rotor 16 includes a ceramic runner 17 having a radially
outward facing sealing surface 5 in rubbing contact with the
radially inward facing sealing surface 10 of the sealing ring 8 to
control leakage across the radial gap 9. At one axial end, the
runner 17 has a radially outward extending flange 18. At this same
axial end, the runner 17 has a radially inward extending flange 19
having axial faces adapted to receive an axial clamping load. The
sealing rotor 16 further includes two metallic annular clamping
members 20, 21 for providing this clamping load.
[0013] The first annular clamping member 21 includes a cylindrical
portion 22 having a radially inward extending flange 23 at one end
and a radially outward extending lip 24 at the other end. The
length and thickness of the cylindrical portion 22 are selected to
impart radial flexibility to the annular clamping member 21 so that
the cylindrical portion 22 acts as a cantilevered beam rigidly
fixed at the inward extending flange 23.
[0014] The second annular clamping member 20 has a cylindrical
portion 25 with a radially inward extending flange 26 at one end
and an axial face 27 at the other end. The cylindrical portion 25
has a plurality of circumferentially extending slots (not shown)
that impart axial flexibility to the cylindrical portion 25
allowing it to compress and expand like a coil spring. The ceramic
runner 17 is flexibly clamped between the axial face 27 and outward
extending lip 24.
[0015] The circumferential seal 15 provides substantially improved
sealing efficiency over metal seal rotors 2 by virtue of the
ceramic runner 17. The thermal growth of the ceramic is low due to
its low coefficient of thermal expansion, thus enabling the runner
17 to more closely track the sealing ring 8 resulting in a more
constant radial gap 9 throughout the entire operating envelope of a
turbine engine.
[0016] Alternatively, because the frictional and wear properties of
the ceramic-to-carbon interface are substantially improved over
those of carbon-to-metal interfaces, the ceramic runner 17 could be
in rubbing contact with the carbon sealing ring 8, thus either
eliminating or reducing the need for cooling of the seal rotor
16.
[0017] Unfortunately, the clamping mechanism employed by Ullah et
al. and other similar mechanisms know within the art are
problematic in that, when used with hard ceramic runners, the
runners are susceptible to fracture induced failures.
[0018] In U.S. Pat. No. 7,905,495, Munson describes a
circumferential seal with a ceramic runner for use within a turbine
engine.
[0019] Referring now to FIGS. 3-5, a seal assembly 28 is shown
including carbon sealing rings 33 contacting a ceramic seal runner
38. The carbon sealing rings 33 are housed within a stator 30
between a flange 31 attached to the stator 30 at a first end and a
removable locking ring 32 at a second end. The stator 30 contacts
and is attached to a housing 29 along the engine. The seal runner
38 is a cylinder or sleeve-shaped element residing about a portion
of the shaft 40. The shaft 40 is attached to a shaft structure 39
so that the shaft structure 39 and elements secured thereto rotate
with the shaft 40. A first end of the shaft 40 includes a flange 41
projecting from the shaft 40 in FIGS. 3 and 4 or attached to a
spool member 45 in FIG. 5. The spool member 45 is further attached
to the shaft structure 39. The second end of the shaft 40 includes
a locking ring 43 which is attached to the shaft 40 in a removable
fashion in FIGS. 3 and 4 or to the spool member 45 in FIG. 5.
[0020] The seal runner 38 is fixed to the shaft 40, so as to rotate
therewith, by applying a compressive force in the direction of the
flange 41 when the locking ring 43 is secured to the shaft 40 or
spool member 45. In FIGS. 3-5, a face seal 44 is provided between
the seal runner 38 and locking ring 43 to prevent gases from
bypassing the seal formed between the inward facing sealing
surfaces 34 along the sealing rings 33 and the outward facing
sealing surface 35 along the seal runner 38. In FIG. 3, a washer 42
is also provided between the seal runner 38 and the flange 41 to
prevent gases from bypassing the seal formed between the inward
facing sealing surfaces 34 and the outward facing sealing surface
35. The face seal 44 is axially compliant so that it is deformed in
response to the relative changes in the length between the seal
runner 38 and the shaft 40 and shaft structure 39.
[0021] The radial position of the seal runner 38 is maintained by a
pair of resilient member 36. In FIG. 3, each resilient member 36
includes a plurality of plates 37 each having deflectable,
resilient fingers. In FIG. 4, each resilient member 36 is a ring
with a u-shaped cross section. The resilient members 36 separately
form a gas-tight seal within the cavity between the seal runner 38
and the shaft structure 39. In FIG. 5, each resilient member 36 is
a ring with a u-shaped cross section attached to comprise a single
structure.
[0022] The assemblies taught by Munson are problematic for several
reasons. First, attachment of the seal runner 38 to the shaft 40
between the flange 41 and the compliant face seal 44 restricts or
limits axial growth of the seal runner 38 and shaft 40, thereby
allowing temperature-induced stress fractures to form along the
seal runner 38. Second, the sealing properties of the face seal 44
are compromised by cyclic expansion and contraction of components
within a turbine engine. Third, the sealing properties of the
resilient members 36 are compromised by cyclic expansion and
contraction of components within a turbine engine.
[0023] Accordingly, what is required is a means for attaching a
ceramic runner to a rotatable metal shaft that allows the runner to
be used in a circumferential seal system and avoids damage to the
runner associated with cyclic expansion and contraction of
components with a turbine engine.
[0024] What is also required is a means for attaching a ceramic
runner within a circumferential seal system to a rotatable metal
shaft that allows for sealing between the runner and shaft while
avoiding damage to the sealing surface during use.
[0025] What is also required is a means for attaching a ceramic
runner within a circumferential seal system which allows for axial
movement of the ceramic runner while avoiding the problems of the
related arts.
[0026] What is also required is a means for attaching a ceramic
runner within a circumferential seal system which avoids radial
expansion of the ceramic runner resulting from the radial expansion
of a rotatable metal shaft and components thereon.
SUMMARY OF THE INVENTION
[0027] An object of the invention is to provide a means for
attaching a ceramic runner to a rotatable metal shaft that allows
the runner to be used in a circumferential seal system and avoids
damage to the runner associated with cyclic expansion and
contraction of components with a turbine engine.
[0028] An object of the invention is to provide a means for
attaching a ceramic runner within a circumferential seal system to
a rotatable metal shaft that allows for sealing between the runner
and shaft while avoiding damage to the sealing surface during
use.
[0029] An object of the invention is to provide a means for
attaching a ceramic runner within a circumferential seal system
which allows for axial movement of the ceramic runner while
avoiding the problems of the related arts.
[0030] An object of the invention is to provide a means for
attaching a ceramic runner within a circumferential seal system
which avoids radial expansion of the ceramic runner resulting from
the radial expansion of a rotatable metal shaft and components
thereon.
[0031] In accordance with embodiments of the invention, the
circumferential seal includes a ceramic runner, an annular seal
ring, at least one tolerance ring, and a pair of sealing rings. The
ceramic runner is circumscribed about a shaft within a recess along
the shaft. The recess is bounded by a shoulder and a clamping ring.
A first annular gap is disposed between a first end of the ceramic
runner and the shoulder. A second end of the ceramic runner
directly contacts the clamping ring. An anti-rotation pin is
attached to the clamping ring and extends into a slot along the
ceramic runner. At least one non-sealing spring mechanism is
disposed between and directly contacts the shoulder and the first
end along the first annular gap. The non-sealing spring mechanism
applies a biasing force onto the ceramic runner toward the clamping
ring. The annular seal ring is circumscribed about the ceramic
runner and disposed within a seal housing so that the annular seal
ring is stationary. The tolerance ring(s) directly contacts the
ceramic runner and the shaft along a second annular gap between the
ceramic runner and the shaft. The ceramic runner is fixed to the
shaft via the tolerance ring(s), anti-rotation pin, and non-sealing
spring mechanism so that the ceramic runner rotates with the shaft.
The non-sealing spring mechanism expands and contracts in response
to expansion and contraction of the ceramic runner. The pair of
sealing rings directly contacts the ceramic runner and the shaft
along the second annular gap. The tolerance ring(s) is disposed
between the pair of sealing rings.
[0032] In accordance with other embodiments of the invention, the
non-sealing spring mechanism is a wave spring or a compression
spring.
[0033] In accordance with other embodiments of the invention, the
non-sealing spring mechanism is compression springs separately
disposed about the first annular gap and attached to the shoulder
along the shaft.
[0034] In accordance with other embodiments of the invention, each
tolerance ring and each sealing ring is separately disposed within
an equal number of annular grooves along the ceramic runner.
[0035] In accordance with other embodiments of the invention, each
tolerance ring and each sealing ring is separately disposed within
an equal number of annular grooves along the shaft.
[0036] In accordance with other embodiments of the invention, the
annular seal ring forms a contact seal or a non-contact seal about
the ceramic runner.
[0037] In accordance with other embodiments of the invention, the
sealing ring is an O-ring, a spring-energized seal, or a
high-temperature metallic seal ring.
[0038] In accordance with embodiments of the invention, the
circumferential seal includes a ceramic runner, an annular seal
ring, at least one tolerance ring, and a pair of sealing rings. The
ceramic runner is circumscribed about a recess along a shaft. The
recess is bounded by a shoulder and a clamping ring. A first
annular gap is disposed between a second end of the ceramic runner
and the clamping ring. A first end of the ceramic runner directly
contacts the shoulder along the shaft. An anti-rotation pin is
attached to the shoulder and extends into a slot along the ceramic
runner. At least one non-sealing spring mechanism is disposed
between and directly contacts the clamping ring and the second end
along the first annular gap. At least one non-sealing spring
mechanism applies a biasing force onto the ceramic runner toward
the shoulder. The annular seal ring is circumscribed about the
ceramic runner and disposed within a seal housing so that the
annular seal ring is stationary. The tolerance ring(s) directly
contacts the ceramic runner and the shaft along a second annular
gap between the ceramic runner and the shaft. The ceramic runner is
fixed to the shaft via the tolerance ring(s), anti-rotation pin,
and non-sealing spring mechanism so that the ceramic runner rotates
with the shaft. The non-sealing spring mechanism expands and
contracts in response to expansion and contraction of the ceramic
runner. The pair of sealing rings directly contacts the ceramic
runner and the shaft along the second annular gap. The tolerance
ring(s) is disposed between the pair of sealing rings.
[0039] In accordance with other embodiments of the invention, the
non-sealing spring mechanism is a wave spring or a compression
spring.
[0040] In accordance with other embodiments of the invention, the
non-sealing spring mechanism is compression springs separately
disposed about the first annular gap and attached to the clamping
ring.
[0041] In accordance with other embodiments of the invention, each
tolerance ring and each sealing ring is separately disposed within
an equal number of annular grooves along the ceramic runner.
[0042] In accordance with other embodiments of the invention, each
tolerance ring and each sealing ring is separately disposed within
an equal number of annular grooves along the shaft.
[0043] In accordance with other embodiments of the invention, the
annular seal ring forms a contact seal or a non-contact seal about
the ceramic runner.
[0044] In accordance with other embodiments of the invention, the
sealing ring is an O-ring, a spring-energized seal, or a
high-temperature metallic seal ring.
[0045] In accordance with embodiments of the invention, the
circumferential seal includes a carrier, a ceramic runner, an
annular seal ring, at least one tolerance ring, and a pair of
sealing rings. The carrier is disposed about and directly contacts
a shaft within a recess along the shaft. The carrier is rotatable
with the shaft. The carrier has a shoulder at one end. The ceramic
runner is circumscribed about the carrier and disposed between the
shoulder and a clamping ring. A first annular gap is disposed
between a first end of the ceramic runner and the shoulder. A
second end of the ceramic runner directly contacts the clamping
ring. An anti-rotation key is attached to the clamping ring and
extends into a slot along the ceramic runner. At least one
non-sealing spring mechanism directly contacts the shoulder and the
first end along the first annular gap. The non-sealing spring
mechanism applies a biasing force onto the ceramic runner toward
the clamping ring. The annular seal ring is circumscribed about the
ceramic runner and disposed within a seal housing so that the
annular seal ring is stationary. The tolerance ring(s) directly
contacts the ceramic runner and the carrier along a second annular
gap between the ceramic runner and the carrier. The ceramic runner
is fixed to the carrier via the tolerance ring(s), anti-rotation
key, and non-sealing spring mechanism so that the ceramic runner
rotates with the carrier. The non-sealing spring mechanism expands
and contracts in response to expansion and contraction of the
ceramic runner. The pair of sealing rings directly contacts the
ceramic runner and the carrier along the second annular gap. The
tolerance ring(s) is disposed between the pair of sealing
rings.
[0046] In accordance with other embodiments of the invention, the
non-sealing spring mechanism is a wave spring or a compression
spring.
[0047] In accordance with other embodiments of the invention, the
non-sealing spring mechanism is compression springs separately
disposed about the first annular gap and attached to the
shoulder.
[0048] In accordance with other embodiments of the invention, each
tolerance ring and each sealing ring is separately disposed within
an annular groove along the carrier.
[0049] In accordance with other embodiments of the invention, each
tolerance ring and each sealing ring is separately disposed within
an annular groove along the ceramic runner.
[0050] In accordance with other embodiments of the invention, the
annular seal ring forms a contact seal or a non-contact seal about
the ceramic runner.
[0051] In accordance with other embodiments of the invention, the
sealing ring is an O-ring, a spring-energized seal, or a
high-temperature metallic seal ring.
[0052] In accordance with embodiments of the invention, the
circumferential seal includes a carrier, a ceramic runner, an
annular seal ring, at least one tolerance ring, and a pair of
sealing rings. The carrier is disposed about and directly contacts
a shaft within a recess along the shaft. The carrier is rotatable
with the shaft. The carrier has a shoulder at one end. The ceramic
runner is circumscribed about the carrier and disposed between the
shoulder and a clamping ring. A first annular gap is disposed
between a second end of the ceramic runner and the clamping ring. A
first end of the ceramic runner directly contacts the shoulder. An
anti-rotation key is attached to the shoulder and extends into a
slot along the ceramic runner. At least one non-sealing spring
mechanism directly contacts the clamping ring and the second end
along the first annular gap. The non-sealing spring mechanism
applies a biasing force onto the ceramic runner toward the
shoulder. The annular seal ring is circumscribed about the ceramic
runner and disposed within a seal housing so that the annular seal
ring is stationary. The tolerance ring(s) directly contacts the
ceramic runner and the carrier along a second annular gap between
the ceramic runner and the carrier. The ceramic runner is fixed to
the carrier via the tolerance ring(s), anti-rotation key, and
non-sealing spring mechanism so that the ceramic runner rotates
with the carrier. The non-sealing spring mechanism expands and
contracts in response to expansion and contraction of the ceramic
runner. The pair of sealing rings directly contacts the ceramic
runner and the carrier along the second annular gap. The tolerance
ring(s) is disposed between the pair of sealing rings.
[0053] In accordance with other embodiments of the invention, the
non-sealing spring mechanism is a wave spring or a compression
spring.
[0054] In accordance with other embodiments of the invention, the
non-sealing spring mechanism is compression springs separately
disposed about the first annular gap and attached to the clamping
ring.
[0055] In accordance with other embodiments of the invention, each
tolerance ring and each sealing ring is separately disposed within
an annular groove along the carrier.
[0056] In accordance with other embodiments of the invention, each
tolerance ring and each sealing ring is separately disposed within
an annular groove along the ceramic runner.
[0057] In accordance with other embodiments of the invention, the
annular seal ring forms a contact seal or a non-contact seal about
the ceramic runner.
[0058] In accordance with other embodiments of the invention, the
sealing ring is an O-ring, a spring-energized seal, or a
high-temperature metallic seal ring.
[0059] In accordance with embodiments of the invention, the
circumferential seal includes a carrier, a ceramic runner, an
annular seal ring, at least one tolerance ring, and a pair of
sealing rings. The carrier is disposed about and directly contacts
a shaft within a recess along the shaft. The carrier is rotatable
with the shaft. The carrier has a shoulder at one end. The ceramic
runner is circumscribed about the carrier and disposed between the
shoulder and a clamping ring. A first annular gap is disposed
between a first end of the ceramic runner and the shoulder. A
second end of the ceramic runner directly contacts the clamping
ring. An anti-rotation screw is attached to the carrier and extends
into a hole along the ceramic runner. At least one non-sealing
spring mechanism directly contacts the shoulder and the first end
along the first annular gap. The non-sealing spring mechanism
applies a biasing force onto the ceramic runner toward the clamping
ring. The annular seal ring is circumscribed about the ceramic
runner and disposed within a seal housing so that the annular seal
ring is stationary. The tolerance ring(s) directly contacts the
ceramic runner and the carrier along a second annular gap between
the ceramic runner and the carrier. The ceramic runner is fixed to
the carrier via the tolerance ring(s), anti-rotation screw, and
non-sealing spring mechanism so that the ceramic runner is
rotatable with the carrier. The non-sealing spring mechanism
expands and contracts in response to expansion and contraction of
the ceramic runner. At least one sealing ring directly contacts the
ceramic runner and the carrier along the second annular gap. The
tolerance ring(s) and anti-rotation screw are disposed between the
pair of sealing rings.
[0060] In accordance with other embodiments of the invention, the
non-sealing spring mechanism is a wave spring or a compression
spring.
[0061] In accordance with other embodiments of the invention, the
non-sealing spring mechanism is compression springs separately
disposed about the first annular gap and attached to the
shoulder.
[0062] In accordance with other embodiments of the invention, each
tolerance ring and one sealing ring is separately disposed within
an annular groove along the carrier and another sealing ring is
disposed within another annular groove along the clamping ring.
[0063] In accordance with other embodiments of the invention, each
tolerance ring and one sealing ring is separately disposed within
an annular groove along the ceramic runner and another sealing ring
is disposed within another annular groove along the clamping
ring.
[0064] In accordance with other embodiments of the invention, the
annular seal ring forms a contact seal or a non-contact seal about
the ceramic runner.
[0065] In accordance with other embodiments of the invention, the
sealing ring is an O-ring, a spring-energized seal, or a
high-temperature metallic seal ring.
[0066] In accordance with embodiments of the invention, the
circumferential seal includes a carrier, a ceramic runner, an
annular seal ring, at least one tolerance ring, and a pair of
sealing rings. The carrier is disposed about and directly contacts
a shaft within a recess along the shaft. The carrier is rotatable
with the shaft. The carrier has a shoulder at one end. A ceramic
runner is circumscribed about the carrier and disposed between the
shoulder and a clamping ring. A first annular gap is disposed
between a second end of the ceramic runner and the clamping ring. A
first end of the ceramic runner directly contacts the shoulder. An
anti-rotation screw is attached to the carrier and extends into a
hole along the ceramic runner. At least one non-sealing spring
mechanism directly contacts the clamping ring and the second end
along the first annular gap. The non-sealing spring mechanism
applies a biasing force onto the ceramic runner toward the
shoulder. The annular seal ring is circumscribed about the ceramic
runner and disposed within a seal housing so that the annular seal
ring is stationary. The tolerance ring(s) directly contacts the
ceramic runner and the carrier along a second annular gap between
the ceramic runner and the carrier. The ceramic runner is fixed to
the carrier via the tolerance ring(s), anti-rotation screw, and
non-sealing spring mechanism so that the ceramic runner is
rotatable with the carrier. The non-sealing spring mechanism
expands and contracts in response to expansion and contraction of
the ceramic runner. At least one sealing ring directly contacts the
ceramic runner and the carrier along the second annular gap. The
tolerance ring(s) and anti-rotation screw are disposed between the
pair of sealing rings.
[0067] In accordance with other embodiments of the invention, the
non-sealing spring mechanism is a wave spring or a compression
spring.
[0068] In accordance with other embodiments of the invention, the
non-sealing spring mechanism is compression springs separately
disposed about the first annular gap and attached to the clamping
ring.
[0069] In accordance with other embodiments of the invention, each
tolerance ring and one sealing ring is separately disposed within
an annular groove along the carrier and another sealing ring is
disposed within another annular groove along the clamping ring.
[0070] In accordance with other embodiments of the invention, each
tolerance ring and one sealing ring is separately disposed within
an annular groove along the ceramic runner and another sealing ring
is disposed within another annular groove along the clamping
ring.
[0071] In accordance with other embodiments of the invention, the
annular seal ring forms a contact seal or a non-contact seal about
the ceramic runner.
[0072] In accordance with other embodiments of the invention, the
sealing ring is an O-ring, a spring-energized seal, or a
high-temperature metallic seal ring.
[0073] During operation of a turbine engine, the shaft rotates with
respect to the annular seal ring. The ceramic runner is configured
to rotate with the shaft via the non-sealing spring mechanism,
anti-rotation element, and tolerance ring(s). The non-sealing
spring mechanism applies an axial load onto the ceramic runner
biasing the runner against the clamping ring attached to the shaft.
Friction between the ceramic runner and clamping ring resists
relative rotational motion between the runner and shaft. Relative
motion is further avoided by the anti-rotation element fixed to and
movable with the shaft. The anti-rotation element contacts the
ceramic runner thereby arresting rotation between runner and shaft.
Contact by the tolerance rings between the ceramic runner and shaft
or a carrier along the shaft further resists relative rotational
motion between the runner and shaft.
[0074] In one of its aspects, the invention utilizes a spring
mechanism which deflects or compresses axially along the length of
the shaft to accommodate thermal expansion axially along the
ceramic runner during operation of the turbine engine so as to
minimize stresses within the ceramic runner thereby minimizing the
possibility of stress induced failures.
[0075] In other of its aspects, the invention utilizes a spring
mechanism which allows the ceramic runner to expand independently
relative to the shaft and/or carrier so as to minimize stresses
within the ceramic runner thereby minimizing the possibility of
stress induced failures.
[0076] In other of its aspects, the invention utilizes sealing
rings between the ceramic runner and shaft or a carrier along the
shaft which prevent oil leakage under the ceramic runner thereby
minimizing oil coking under the runner.
[0077] In other of its aspects, the invention utilizes sealing
rings between the ceramic runner and shaft or a carrier along the
shaft about the tolerance ring which prevent oil from contacting
the tolerance ring(s) thereby avoiding slippage between the runner
and shaft or carrier.
[0078] In other of its aspects, the invention utilizes one or more
sealing rings between the ceramic runner and shaft or a carrier
along the shaft to radially deflect and accommodate changes in the
clearance between the runner and shaft or carrier as the shaft
and/or carrier expands thereby avoiding radial expansion by and
damage to the runner.
[0079] In other of its aspects, the invention utilizes one or more
gapped tolerance rings between the ceramic runner and shaft or
carrier which expands circumferentially so as to accommodate
changes in the clearance between the runner and shaft or carrier as
the shaft and/or carrier expands thereby avoiding radial expansion
by and damage to the runner.
[0080] In other of its aspects, the invention separates axial
functionality of the spring mechanism from sealing function of the
sealing rings thereby minimizing degradation of the sealing rings
by thermally induced expansion and contraction cycles within a gas
turbine engine.
[0081] In other of its aspects, the invention separates radial
functionality of the tolerance ring(s) from sealing function of the
sealing rings thereby minimizing degradation of the sealing rings
by thermally induced expansion and contraction cycles within a gas
turbine engine.
[0082] The above and other objectives, features, and advantages of
the embodiments of the invention will become apparent from the
following description read in connection with the accompanying
drawings, in which like reference numerals designate the same or
similar elements.
BRIEF DESCRIPTION OF THE DRAWINGS
[0083] Additional aspects, features, and advantages of the
invention will be understood and will become more readily apparent
when the invention is considered in the light of the following
description made in conjunction with the accompanying drawings.
[0084] FIG. 1 is a cross-sectional view illustrating a
circumferential seal with metal rotor as described by Ullah et al.
in U.S. Pat. No. 6,322,081.
[0085] FIG. 2 is a cross-sectional view illustrating a
circumferential seal with ceramic rotor as described by Ullah et
al. in U.S. Pat. No. 6,322,081.
[0086] FIG. 3 is a cross-section view illustrating a
circumferential seal with a ceramic runner attached compressively
along a shaft between a flange and a locking ring and radially
supported along the shaft via a pair of resilient members each
having a plurality of plates as described by Munson in U.S. Pat.
No. 7,905,395.
[0087] FIG. 4 is a cross-section view illustrating a
circumferential seal with a ceramic runner attached compressively
along a shaft between a flange and a locking ring and radially
supported along the shaft via a pair of resilient members each
being a ring with u-shaped cross section as described by Munson in
U.S. Pat. No. 7,905,395.
[0088] FIG. 5 is a cross-section view illustrating a
circumferential seal with a ceramic runner attached compressively
along a spool member between a flange and a locking ring and
radially supported along the spool member via a pair of resilient
members each being a ring with u-shaped cross section which form a
single structure as described by Munson in U.S. Pat. No.
7,905,395.
[0089] FIG. 6a is a cross-section view illustrating a
circumferential seal with a ceramic runner recessed along a
rotatable shaft and attached thereto via at least one anti-rotation
pin and an annular spring wherein sealing and tolerance rings are
disposed between the runner and shaft within annular grooves along
the runner in accordance with an embodiment of the invention.
[0090] FIG. 6b is a cross-section view illustrating the
anti-rotation pin in FIG. 6a within a slot or hole along the
ceramic runner in accordance with an embodiment of the
invention.
[0091] FIG. 6c is a side view illustrating the tolerance ring in
FIG. 6a with a gap in accordance with an embodiment of the
invention.
[0092] FIG. 6d is a cross-section view illustrating a
circumferential seal with a ceramic runner recessed along a
rotatable shaft and attached thereto via at least one anti-rotation
pin and an annular spring wherein the spring mechanism is provided
between the ceramic runner and a clamping ring in accordance with
an embodiment of the invention.
[0093] FIG. 7a is a cross-section view illustrating a
circumferential seal with a ceramic runner recessed along a
rotatable shaft and attached thereto via at least one anti-rotation
pin and an annular spring wherein sealing and tolerance rings are
disposed between the runner and shaft within annular grooves along
the shaft in accordance with an embodiment of the invention.
[0094] FIG. 7b is a cross section view illustrating a compression
spring disposed between the ceramic runner and shaft in FIG. 7a in
accordance with an embodiment of the invention.
[0095] FIG. 7c is a cross-section view illustrating several
compression springs each within a hole along a portion of the shaft
in accordance with an embodiment of the invention.
[0096] FIG. 8a is a cross-section view illustrating a
circumferential seal with a ceramic runner disposed along a carrier
recessed along a rotatable shaft and attached to the carrier via at
least one key and a plurality of compression springs wherein
sealing and tolerance rings are disposed between the runner and
shaft within annular grooves along the carrier in accordance with
an embodiment of the invention.
[0097] FIG. 8b is a cross-section view illustrating the key in FIG.
8a within a slot along the ceramic runner in accordance with an
embodiment of the invention.
[0098] FIG. 8c is a cross-section view illustrating several
compression springs each within a hole along a portion of the
carrier in accordance with an embodiment of the invention.
[0099] FIG. 8d is a cross section view illustrating an annular
spring disposed between the ceramic runner and carrier in FIG. 8a
in accordance with an embodiment of the invention.
[0100] FIG. 8e is a cross-section view illustrating a
circumferential seal with a ceramic runner disposed along a carrier
recessed along a rotatable shaft wherein the spring mechanism is
disposed between the ceramic runner and a clamping ring in
accordance with an embodiment of the invention.
[0101] FIG. 9a is a cross-section view illustrating a
circumferential seal with a ceramic runner disposed along a carrier
recessed along a rotatable shaft and attached to the carrier via at
least one anti-rotation screw and a plurality of compression
springs wherein a first sealing ring and tolerance ring are
disposed between the runner and shaft within annular grooves along
the shaft and a second sealing ring is disposed between the runner
and a clamping ring along a groove within the clamping ring in
accordance with an embodiment of the invention.
[0102] FIG. 9b is a cross-section view illustrating the
anti-rotation screw in FIG. 9a disposed within a hole along the
carrier in accordance with an embodiment of the invention.
[0103] FIG. 9c is a cross-section view illustrating the
anti-rotation screw in FIG. 9a disposed within a hole along the
ceramic runner in accordance with an embodiment of the
invention.
[0104] FIG. 9d is a cross-section view illustrating a
circumferential seal with a ceramic runner disposed along a carrier
recessed along a rotatable shaft and attached to the carrier via at
least one anti-rotation screw and a plurality of compression
springs wherein a first sealing ring and tolerance ring are
disposed between the runner and shaft within annular grooves along
the shaft and a second sealing ring is disposed between the runner
and the carrier along a groove within the carrier in accordance
with an embodiment of the invention.
[0105] FIG. 9e is a cross-section view illustrating a
circumferential seal with a ceramic runner disposed along a carrier
recessed along a rotatable shaft wherein a spring mechanism is
disposed between the ceramic runner and a clamping ring in
accordance with an embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0106] Reference will now be made in detail to several embodiments
of the invention that are illustrated in the accompanying drawings.
Wherever possible, same or similar reference numerals are used in
the drawings and the description to refer to the same or like
parts. The drawings are in simplified form and are not to precise
scale.
[0107] While features of various embodiments are separately
described throughout this document, it is understood that such
features could be combined to form a single embodiment.
[0108] Referring now to FIGS. 6a and 7a, the circumferential seal
46 is illustrated for descriptive purposes along an upper half of
an exemplary shaft 57 rotatable about a centerline 67 along a
turbine engine. While the shaft 57 is generally represented as a
cylindrical-shaped element, other configurations are possible.
[0109] The outer diameter 100 of the shaft 57 is shown including a
recess 98. The recess 98 could include one or more regions along
the shaft 57 each having a diameter smaller than the outer diameter
100 of the shaft 57. The exemplary shafts 57 in FIGS. 6a and 7a
have a recess 98 which includes three sections arranged end-to-end
in a stepwise fashion, whereby the first section accommodates a
ceramic runner 52, the second section accommodates a clamping ring
74, and the third section accommodates a locking ring 75. The
clamping ring 74 and locking ring 75 are composed of materials
suitable for use within a turbine engine. Materials should be wear,
failure, and temperature resistant. Exemplary compositions include
metals, preferably compositions of steel. The locking ring 75
secures the various components described herein to the shaft 57
about the recess 98. It is understood that the recess 98 could
include one or more sections as well as other shapes and designs
which facilitate attachment of elements required to provide
circumferential sealing along a shaft 57.
[0110] The interface between the outer diameter 100 of the shaft 57
and the outer diameter 62 of the recess 98 is defined by a first
shoulder 55. The recess 98 could include additional shoulders
depending on the profile of the recess 98, although such features
are optional and design dependent. For example, the recess 98 in
FIGS. 6a and 7a is shown with a second shoulder 56 at the interface
between the regions for the ceramic runner 52 and clamping ring 74
formed at the discontinuity of the outer diameters 62, 79. The
second shoulder 56 acts as a mechanical stop which fixes the
clamping ring 74 at a prescribed distance from the first shoulder
55. A clearance fit could be provided between the outer diameter 79
of the shaft 57 and inner diameter 83 along the clamping ring 74 so
that the clamping ring 74 is slidable with respect to the shaft 57.
The clamping ring 74 is secured to the shaft 57 via the locking
ring 75 which could include threads along its inner diameter 84
which engage a complementary thread arrangement along the outer
diameter 80 of the shaft 57. In another example, the recess 98 at
the interface between the regions for the clamping ring 74 and
locking ring 75 is shown without a shoulder because these regions
include outer diameters 79, 80 which are approximately equal.
[0111] The ceramic runner 52 is a cylindrically-shaped or
sleeve-shaped element which is slid onto the shaft 57 during
assembly so as to circumscribe the shaft 57 about the recess 98.
The ceramic runner 52 is composed of a ceramic composition suitable
for use within a turbine engine. In preferred embodiments, the
ceramic composition should be wear, failure, and temperature
resistant. Exemplary, non-limiting compositions include silicon
nitride and silicon carbide.
[0112] The ceramic runner 52 has an inner diameter 61 which is
larger than the outer diameter 62 of the shaft 57 along the recess
98 resulting in a second annular gap 72 which avoids direct contact
between the ceramic runner 52 and shaft 57. The distance between a
first end 53 and a second end 54 of the ceramic runner 52 is less
than the axial distance between the first shoulder 55 and second
shoulder 56. The first end 53 is positioned adjacent to the first
shoulder 55 so that a first annular gap 73 separates the first end
53 from the first shoulder 55. The axial length of the first
annular gap 73 is sized to accommodate a spring mechanism. The
spring mechanism provides no sealing functionality. Although spring
mechanisms are described herein, it is understood that such
mechanisms could include other non-sealing devices which at least
resist compression and are resilient. The second end 54 directly
contacts the clamping ring 74 so that the second end 54 is
generally aligned with the second shoulder 56.
[0113] In some embodiments, the spring mechanism could be a single
annular spring 58, as represented in FIGS. 6a and 7a. Exemplary
annular springs 58 include a wave spring or a compression spring or
the like which circumscribe the shaft 57 within the first annular
gap 73. The length of the annular spring 58 in its uncompressed
state requires the annular spring 58 to be partially compressed
when assembled between the ceramic runner 52 and shaft 57. The
annular spring 58 is compressed by contact with the first shoulder
55 at one end of the annular spring 58 and the first end 53 at
another end of the annular spring 58. In its partially compressed
state, the annular spring 58 communicates a biasing force 99
axially onto the ceramic runner 52 thereby pressing the ceramic
runner 52 onto the clamping ring 74. The biasing force 99 is
preferred to maintain contact between the second end 54 of the
ceramic runner 52 and the clamping ring 74 during operation of a
turbine engine, thereby avoiding axial separation between the
ceramic runner 52 and clamping ring 74 which could occur because of
thermally induced expansion and contraction of components within
the engine. The biasing force 99 also resists rotational sliding
motion between the ceramic runner 52 and clamping ring 74 at the
second end 54. The annular spring 58 is partially compressed at or
below ambient conditions so as to allow for further compression of
the annular spring 58 during operation of a turbine engine. This
feature allows the annular spring 58 to expand and contract with
axial expansion and contraction of the ceramic runner 52 as the
ceramic runner 52 and other components heat and cool.
[0114] In other embodiments, the spring mechanism could include a
plurality of compression springs 88 or the like, as represented in
FIGS. 7b and 7c. Each compression spring 88 is axially aligned
along the direction of the shaft 57 as shown in FIG. 7b. The
compression springs 88 are further separately disposed about the
diameter of the shaft 57 along the first shoulder 55 as generally
shown in FIG. 7c, so as to communicate a biasing force 99
symmetrically about the ceramic runner 52 in the axial direction.
One end of each compression spring 88 could reside within a
complementary shaped hole 94 so that a portion of the compression
spring 88 extends into the first annular gap 73 with sufficient
length to contact the first end 53 along the ceramic runner 52. The
compression spring 88 could be mechanically fixed to the hole 94
via an interference fit or freely movable within the hole 94. The
compression springs 88 are preferred to be sufficiently long so
that each is partially compressed when assembled between the shaft
57 and ceramic runner 52. Partial compression of the compression
spring 88 maintains a biasing force 99 onto the ceramic runner 52
so that the second end 54 of the ceramic runner 52 is biased toward
and contacts the clamping ring 74. The biasing force 99 maintains
contact between the second end 54 of the ceramic runner 52 and the
clamping ring 74 during operation of a turbine engine, thereby
avoiding axial separation thereof because of thermally induced
expansion and contraction of ceramic runner 52 and other components
within the engine. The biasing force 99 also resists rotational
sliding motion between the ceramic runner 52 and clamping ring 74
at the second end 54. The compression springs 88 are partially
compressed at or below ambient conditions so as to allow for
further compression of the compression springs 88 during operation
of a turbine engine. This feature allows the compression springs 88
to expand and contract with expansion and contraction of the
ceramic runner 52 as the ceramic runner 52 and other components
heat and cool.
[0115] In other embodiments, the first end 53 could directly
contact the first shoulder 55 and the spring mechanism, either the
annular spring 58 or the compression springs 88, is disposed
between the second end 54 and clamping ring 74, as generally
represented in FIG. 6d. The first annular gap 73 now resides
between the second end 54 and clamping ring 74. The biasing force
99 is directed toward the shoulder 55. The anti-rotation pin 76
partially resides within a hole 77 and is attached to the shaft 57
along the first shoulder 55 so as to extend toward the ceramic
runner 52. Another portion of the anti-rotation pin 76 resides
within a slot 78 along the first side 53. The spring mechanisms
could be attached to the clamping ring 74 in a similar manner as
otherwise described herein for attachment to the shaft 57.
[0116] Referring again to FIGS. 6a and 7a, the second annular gap
72 between the inner diameter 61 of the ceramic runner 52 and outer
diameter 62 of the shaft 57 is shown with a pair of tolerance rings
70, 71. Although two tolerance rings 70, 71 are shown and
described, it is understood that the second annular gap 72 could
include one or more such rings. The tolerance rings 70, 71 are
generally described as a ring-shaped element with corrugations
along an inward face or an outward face and with a gap 87, the
latter feature represented in FIG. 6c (corrugated structure not
shown). Tolerance rings 70, 71 provide no sealing functionality.
When attached between the inner diameter 61 and outer diameter 62
along the gap 72, the tolerance rings 70, 71 conform to the bore
and are self-retaining thereby resisting rotational slippage
between the ceramic runner 52 and shaft 57. The tolerance rings 70,
71 could allow for axial slippage so as to avoid stresses within
the ceramic runner 52. Exemplary tolerance rings 70, 71 are the BN
Series devices sold by USA Tolerance Rings of Pennington, N.J.
(United States). The tolerance rings 70, 71 maintain proper fit
between the ceramic runner 52 and shaft 57 by expanding
circumferentially to the radial clearance between the inner
diameter 61 and outer diameter 62 by closing the gap 87. This
functionality avoids radial expansion of the ceramic runner 52
which could damage the runner 52. Each tolerance ring 70, 71
resides within an annular groove 63, 65, respectively. The annular
grooves 63, 65 are disposed along the inner diameter 61 of the
ceramic runner 52 as shown in FIG. 6a or along the outer diameter
52 of the shaft 57 as shown in FIG. 7a. The depth of each annular
groove 63, 65 should allow assembly of the ceramic runner 52 onto
the shaft 57 and proper placement of the tolerance rings 70, 71
along the shaft 57 while ensuring sufficient contact between the
tolerance rings 70, 71 and inner and outer diameters 61, 62 for
proper function of the tolerance rings 70, 71. The annular grooves
63, 65 should be at least as wide as the tolerance rings 70, 71,
preferably providing a tolerance fit which allows each tolerance
ring 70, 71 to be secured within the respective annular groove 63,
65.
[0117] Referring again to FIGS. 6a and 7a, the second annular gap
72 between the inner diameter 61 of the ceramic runner 52 and outer
diameter 62 of the shaft 57 is shown with a pair of sealing rings
68, 69. Sealing rings 68, 69 could include devices known within the
art, examples including, but not limited to, multi-directional
O-rings, unidirectional spring-energized seals, high-temperature
metallic seal rings, or other comparable devices sold by the Parker
Hannifin Corporation located in North Haven, Conn. (United States)
or other suppliers. Other exemplary seals include those sold under
the Trademark OMNISEAL.RTM. by Saint-Gobain Performance Plastics
Corporation of Aurora, Ohio (United States). When assembled between
the inner diameter 61 and outer diameter 62 about the second
annular gap 72, the sealing rings 68, 69 conform to the bore
thereby further resisting rotational slippage between the ceramic
runner 52 and shaft 57. The seal rings 68, 69 could allow for axial
slippage so as to avoid stresses within the ceramic runner 52. Each
sealing ring 68, 69 resides within an annular groove 64, 66,
respectively. The annular grooves 64, 66 are disposed along the
inner diameter 61 of the ceramic runner 52 as shown in FIG. 6a or
along the outer diameter 52 of the shaft 57 as shown in FIG. 7a.
The depth of each annular groove 64, 66 should be sufficiently deep
so as to allow assembly of the ceramic runner 52 onto the shaft 57
and proper placement of the sealing rings 68, 69 along the shaft 57
while ensuring sufficient contact between the sealing rings 68, 69
and inner and outer diameters 61, 62 for proper function of the
sealing rings 68, 69. The grooves 64, 66 should be at least as wide
as the sealing rings 68, 69, preferably with a tolerance fit
allowing each sealing ring 68, 69 to be secured within the
respective annular groove 64, 66.
[0118] The sealing rings 68, 69 are disposed about the tolerance
rings 70, 71, as represented in FIGS. 6a and 7a. The sealing rings
68, 69 are oriented along the second annular gap 72 so that the
sealing direction 101 of the sealing rings 68, 69 avoids or at
least minimizes oil and other contaminants within the higher and/or
lower pressure sides 81, 82 from entering the second annular gap 72
and interacting with the tolerance rings 70, 71. This feature
minimizes degradation to the performance of the tolerance rings 70,
71 caused by oil and other contaminants and further minimizes oil
coking under the ceramic runner 52.
[0119] The clamping ring 74 further includes at least one
anti-rotation pin 76. The anti-rotation pin 76 could reside within
a complementary shaped hole 77 along the clamping ring 74 so that a
portion of the anti-rotation pin 76 extends toward the ceramic
runner 52. The anti-rotation pin 76 could be mechanically fixed to
the hole 77 via an interference fit or slidable therein via a
clearance fit. The portion of the anti-rotation pin 76 extending
from the clamping ring 74 could reside within a slot 78 along the
ceramic runner 52. The slot 78 could extend from the inner diameter
61 of the ceramic runner 52 and partially traverse the thickness of
the ceramic runner 52 in the direction of the outward facing
sealing surface 60, as represented in FIG. 6b. The slot 78 is
dimensioned to avoid contact with the end and sides of the
anti-rotation pin 76, see FIGS. 6a and 6b, respectively. The
anti-rotation pin 76 could contact a side wall 102, the latter
shown in FIG. 6b, along the slot 78 when the ceramic runner 52
rotates relative to the clamping ring 74. The degree of rotation
before contact between the anti-rotation pin 76 and side wall 102
is determined by the clearance therebetween, which is design
dependent.
[0120] An annular seal ring 49 is circumferentially disposed about
the outward facing sealing surface 60 of the ceramic runner 52. The
annular seal ring 49 includes an inward facing sealing surface 59
which interacts with the outward facing sealing surface 60 to form
the circumferential sealing of the present invention. The annular
seal ring 49 is a ring-shaped element with or without segmentation.
In some embodiments, the inward facing sealing surface 59 could
physically contact the outward facing sealing surface 60 during
rotation of the ceramic runner 52 and shaft 57 to provide a contact
seal. In other embodiments, the inward facing sealing surface 59
and outward facing sealing surface 60 could be separated by a gap
to form a non-contact seal. In yet other embodiments, the outward
facing sealing surface 60 could include hydrodynamic pockets which
form a thin-film between inward and outward facing sealing surfaces
59, 60 during rotation of the ceramic runner 52.
[0121] The annular seal ring 49 resides within a seal housing 47
and is secured thereto via a support ring 50 and a retaining ring
51 or other like elements via methods and designs known within the
art. The annular seal ring 49 is stationary rotationally with
respect to the seal housing 47. As such, the annular seal ring 49
does not rotate with respect to the seal housing 47. The annular
seal ring 49 could move radially inward and outward to track radial
excursions of the ceramic runner 52. The seal housing 47 is secured
to a housing 48 comprising a turbine engine. Both seal housing 47
and housing 48 are shown in a generalized form for descriptive
purposes only and are not intended to limit the scope of the
claimed invention. Arrangement of the annular seal ring 49, seal
housing 47, and housing 48 about the ceramic runner 52 and shaft 57
generally defines a higher pressure side 81 and a lower pressure
side 82. The higher pressure side 81 could define the air or gas
side within a turbine engine. The lower pressure side 82 could
define the bearing or oil side within a turbine engine.
[0122] Referring again to FIGS. 6a and 7a, the outward facing
sealing surface 60 along the ceramic runner 52 is shown
approximately radially aligned with the outer diameter 100 of the
shaft 57. However, it is understood that outward facing sealing
surface 60 could extend above or be depressed below the outer
diameter 100 in other embodiments of the invention. In yet other
embodiments, it is possible for the outward facing sealing surface
60 to move radially inward and outward with respect to the outer
diameter 100 during operation of a turbine engine.
[0123] Referring now to FIG. 8a, the circumferential seal 46 is
illustrated for descriptive purposes along an upper half of an
exemplary shaft 57 along a turbine engine rotatable about a
centerline 67. In this embodiment, a ceramic runner 52 is attached
to a carrier 91 to form a cartridge 90. The cartridge 90
facilitates assembly of components comprising the circumferential
seal 46 prior to attachment to a shaft 57. This approach simplifies
assembly and repair of a turbine engine.
[0124] The outer diameter 100 of the shaft 57 is shown including a
recess 98. The recess 98 could include one or more regions along
the shaft 57 each having a diameter smaller than the outer diameter
100. The exemplary shaft 57 has a recess 98 which includes a single
section to accommodate a locking ring 75 and a carrier 91, the
latter supporting a ceramic runner 52 and a clamping ring 74. The
clamping ring 74 and locking ring 75 are composed of materials
suitable for use within a turbine engine. Materials should be wear,
failure, and temperature resistant. Exemplary compositions include
metals, preferably compositions of steel. The locking ring 75
secures the carrier 91 with the various components described herein
to the shaft 57 about the recess 98. It is understood that the
recess 98 could include one or more sections as well as other
shapes and designs which facilitate attachment of elements required
to provide circumferential sealing along a shaft 57.
[0125] The interface between the outer diameter 100 of the shaft 57
and the outer diameter 62 of the recess 98 defines a first shoulder
55. The recess 98 could include additional shoulders depending on
the profile of the recess 98, although such features are optional
and design dependent. For example, the recess 98 could include
other shoulders each defined by a discontinuity where two outer
diameters differ.
[0126] The carrier 91 is a ring-shaped element with a flange 104
which extends perpendicular from one end of an annular ring 105. In
some embodiments, a clearance fit is provided for assembly purposes
between the outer diameter 62 of the shaft 57 and inner diameter 85
of the carrier 91 so that the carrier 91 is slidable with respect
to the shaft 57. In other embodiments, an interference fit is
provided between the outer diameter 62 and the inner diameter 85
and the carrier 91 is heated to open the inner diameter 85 prior to
sliding the carrier 91 onto the shaft 57. The carrier 91 is then
cooled to fix the carrier 91 to the shaft 57. The flange 104 should
contact the shoulder 55 in addition to the annular ring 105
contacting the surface of the shaft 57. The carrier 91 is composed
of materials suitable for use within a turbine engine. Materials
should be wear, failure, and temperature resistant. Exemplary
compositions include metals, preferably compositions of steel with
a coefficient of thermal expansion comparable to that of the shaft
57 so that carrier 91 tracks the expansion and contraction of the
shaft 57.
[0127] The carrier 91 could likewise include one or more shoulders
along the surface of the annular ring 105. The interface between
the annular surface 107 along the carrier 91 and the outer diameter
106 of the carrier 91 defines a first shoulder 92. The carrier 91
could also include a first segment with an outer diameter 106 and a
second segment with an outer diameter 86. The outer diameter 106
could be larger than the other outer diameter 86 so that a second
shoulder 103 is provided at the discontinuity between the two outer
surfaces. A clearance fit could be provided between the outer
diameter 86 of the carrier 91 and inner diameter 83 along the
clamping ring 74 so that the clamping ring 74 is slidable with
respect to the carrier 91. The carrier 91 and clamping ring 74 are
secured to the shaft 57 via the locking ring 75. The locking ring
75 contacts both the clamping ring 74 and the end 93 of the carrier
91 as illustrate in FIG. 8a. The locking ring 75 includes threads
along its inner diameter 84 which engage a complementary thread
arrangement along the outer diameter 80 of the shaft 57. The force
applied by the locking ring 75 onto the carrier 91 and clamping
ring 74 should be sufficient to prevent relative motion with
respect to the shaft 57.
[0128] The ceramic runner 52 is a cylindrically-shaped or
sleeve-shaped element which is slid onto the shaft 57 during
assembly so as to circumscribe the carrier 91. The ceramic runner
52 is composed of a ceramic composition suitable for use within a
turbine engine. In preferred embodiments, the ceramic composition
should be wear, failure, and temperature resistant. Exemplary,
non-limiting compositions include silicon nitride and silicon
carbide.
[0129] The ceramic runner 52 has an inner diameter 61 which is
larger than the outer diameter 106 of the carrier 91 resulting in a
second annular gap 72 which avoids direct contact between the
ceramic runner 52 and carrier 91. The distance between a first end
53 and a second end 54 of the ceramic runner 52 is less than the
axial distance between the first shoulder 92 and second shoulder
103. The first end 53 is positioned adjacent to the first shoulder
92 so that a first annular gap 73 separates the first end 53 from
the first shoulder 92. The axial length of the first annular gap 73
is sized to accommodate a spring mechanism. The spring mechanism
provides no sealing functionality. Although spring mechanisms are
described herein, it is understood that such mechanisms could
include other non-sealing devices which at least resist compression
and are resilient. The second end 54 directly contacts the clamping
ring 74 so that the second end 54 is generally aligned with the
second shoulder 103.
[0130] In some embodiments, the spring mechanism could include a
plurality of compression springs 88 as represented in FIG. 8a and
generally described in FIGS. 7b and 7c. Each compression spring 88
is axially aligned along the direction of the shaft 57. The
compression springs 88 are further separately disposed about the
shaft 57 along the flange 104 of the carrier 91, as generally shown
in FIG. 8c, so as to communicate a biasing force 99 symmetrically
about the ceramic runner 52 in the axial direction. One end of each
compression spring 88 could reside within a complementary shaped
hole 94 within the flange 104 so that a portion of the compression
spring 88 extends into the first annular gap 73 with sufficient
length to contact the first end 53 along the ceramic runner 52. The
compression spring 88 could be mechanically fixed to the hole 94
via an interference fit or freely movable within the hole 94. The
compression springs 88 are preferred to be sufficiently long so
that each is partially compressed when assembled between the
carrier 91 and ceramic runner 52. Partial compression of the
compression spring 88 maintains a biasing force 99 onto the ceramic
runner 52 so that the second end 54 of the ceramic runner 52 is
biased toward and contacts the clamping ring 74. The biasing force
99 maintains contact between the second end 54 of the ceramic
runner 52 and the clamping ring 74 during operation of a turbine
engine, thereby avoiding separation thereof because of thermally
induced expansion and contraction of ceramic runner 52 and other
components within the engine. The biasing force 99 also resists
rotational sliding motion between the ceramic runner 52 and
clamping ring 74 at the second end 54. The compression springs 88
are partially compressed at or below ambient conditions so as to
allow for further compression of the compression springs 88 during
operation of a turbine engine. This feature allows the compression
springs 88 to expand and contract with expansion and contraction of
the ceramic runner 52 as the ceramic runner 52 and other components
heat and cool.
[0131] In other embodiments, the spring mechanism could be a single
annular spring 58, as represented in FIG. 8d. Exemplary annular
springs 58 include a wave spring or a compression spring or the
like which circumscribe the shaft 57 within the first annular gap
73 between the first end 53 of the ceramic runner 52 and first
shoulder 92 along the carrier 91. The length of the annular spring
58 in its uncompressed state requires the annular spring 58 to be
partially compressed when assembled between the ceramic runner 52
and carrier 91. The annular spring 58 is compressed by contact with
the first shoulder 92 at one side of the annular spring 58 and the
first end 53 at another side of the annular spring 58. In its
partially compressed state, the annular spring 58 communicates a
biasing force 99 axially onto the ceramic runner 52 thereby
pressing the ceramic runner 52 onto the clamping ring 74. The
biasing force 99 is preferred to maintain contact between the
second end 54 of the ceramic runner 52 and the clamping ring 74
during operation of a turbine engine, thereby avoiding separation
between the ceramic runner 52 and clamping ring 74 which could
occur because of thermally induced expansion and contraction of
components within the engine. The biasing force 99 also resists
rotational sliding motion between the ceramic runner 52 and the
clamping ring 74 at the second end 54. The annular spring 58 is
partially compressed at or below ambient conditions so as to allow
for further compression of the annular spring 58 during operation
of a turbine engine. This feature allows the annular spring 58 to
expand and contract with axial expansion and contraction of the
ceramic runner 52 as the ceramic runner 52 and other components
heat and cool.
[0132] In other embodiments, the first end 53 could directly
contact the first shoulder 92 and the spring mechanism, either an
annular spring 58 or compression springs 88, is disposed between
the second end 54 and clamping ring 74, as generally represented in
FIG. 8e. The biasing force 99 is directed toward the flange 104.
The anti-rotation key 89 is attached to the flange 104 along the
carrier 91 so as to extend toward the ceramic runner 52. A portion
of the anti-rotation key 89 resides within a slot 78 along the
first side 53. The spring mechanisms could be attached to the
clamping ring 74 as described in FIG. 8a. For example, each
compression spring 88 could partially reside within a hole 94 so as
to extend across the first annular gap 73 and contact the second
end 54.
[0133] Referring again to FIG. 8a, the second annular gap 72
between the inner diameter 61 of the ceramic runner 52 and outer
diameter 106 of the carrier 91 is shown with a pair of tolerance
rings 70, 71. Although two tolerance rings 70, 71 are shown and
described, it is understood that the second annular gap 72 could
include one or more such rings. The tolerance rings 70, 71 are
generally described as a ring-shaped element with corrugations
along an inward face or an outward face and with a gap 87, the
latter feature represented in FIG. 6c. Tolerance rings 70, 71
provide no sealing functionality. When attached between the inner
diameter 61 and outer diameter 106 along the gap 72, the tolerance
rings 70, 71 conform to the bore and are self-retaining thereby
resisting rotational slippage between the ceramic runner 52 and
carrier 91. The tolerance rings 70, 71 could allow for axial
slippage so as to avoid stresses within the ceramic runner 52.
Exemplary tolerance rings 70, 71 are the BN Series devices sold by
USA Tolerance Rings of Pennington, N.J. (United States). The
tolerance rings 70, 71 maintain proper fit between the ceramic
runner 52 and carrier 91 by expanding circumferentially to the
radial clearance between the inner diameter 61 and outer diameter
106 by closing the gap 87. This functionality avoids radial
expansion of the ceramic runner 52 which could damage the runner
52. Each tolerance ring 70, 71 resides within an annular groove 63,
65, respectively. The annular grooves 63, 65 could be disposed
along the inner diameter 61 of the ceramic runner 52 in an
arrangement similar to that shown in FIG. 6a or along the outer
diameter 106 of the carrier 91 as shown in FIG. 8a. The depth of
each annular groove 63, 65 should allow assembly of the ceramic
runner 52 onto the carrier 91 and proper placement of the tolerance
rings 70, 71 along the carrier 91 while ensuring sufficient contact
between the tolerance rings 70, 71 and inner and outer diameters
61, 106 for proper function of the tolerance rings 70, 71. The
annular grooves 63, 65 should be at least as wide as the tolerance
rings 70, 71, preferably providing a tolerance fit which allows
each tolerance ring 70, 71 to be secured within the respective
annular groove 63, 65.
[0134] Referring again to FIG. 8a, the second annular gap 72
between the inner diameter 61 of the ceramic runner 52 and outer
diameter 106 of the carrier 91 is shown with a pair of sealing
rings 68, 69. Sealing rings 68, 69 could include devices known
within the art, examples including, but not limited to,
multi-directional O-rings, unidirectional spring-energized seals,
high-temperature metallic seal rings, or other comparable devices
sold by the Parker Hannifin Corporation located in North Haven,
Conn. (United States) or other suppliers. Other exemplary seals
include those sold under the Trademark OMNISEAL.RTM. by
Saint-Gobain Performance Plastics Corporation of Aurora, Ohio
(United States). When assembled between the inner diameter 61 and
outer diameter 106 along the second annular gap 72, the sealing
rings 68, 69 conform to the bore thereby further resisting
rotational slip between the ceramic runner 52 and carrier 91. The
sealing rings 68, 69 could allow for axial slippage so as to avoid
stresses within the ceramic runner 52. Each sealing ring 68, 69
resides within an annular groove 64, 66, respectively. The annular
grooves 64, 66 are disposed along the inner diameter 61 of the
ceramic runner 52 in an arrangement similar to that shown in FIG.
6a or along the outer diameter 106 of the carrier 91 as shown in
FIG. 8a. The depth of each annular groove 64, 66 should be
sufficiently deep so as to allow assembly of the ceramic runner 52
onto the carrier 91 and proper placement of the sealing rings 68,
69 along the carrier 91 while ensuring sufficient contact between
the sealing rings 68, 69 and inner and outer diameters 61, 106 for
proper function of the sealing rings 68, 69. The grooves 64, 66
should be at least as wide as the sealing rings 68, 69, preferably
with a tolerance fit allowing each sealing ring 68, 69 to be
secured within the respective annular groove 64, 66.
[0135] The sealing rings 68, 69 are disposed about the tolerance
rings 70, 71, as represented in FIG. 8a. The sealing rings 68, 69
are oriented along the second annular gap 72 so that the sealing
direction 101 of the sealing rings 68, 69 avoids or at least
minimizes oil and other contaminants within the higher and/or lower
pressure sides 81, 82 from entering the second annular gap 72 and
interacting with the tolerance rings 70, 71. This feature minimizes
degradation to the performance of the tolerance rings 70, 71 caused
by oil and other contaminants and further minimizes oil coking
under the ceramic runner 52.
[0136] The clamping ring 74 further includes at least one
anti-rotation key 89. The anti-rotation key 89 is attached or fixed
to one side of the clamping ring 74 via techniques understood in
the art so that a portion of the anti-rotation key 89 extends
toward the ceramic runner 52. The portion of the anti-rotation key
89 extending from the clamping ring 74 could reside within a slot
78 along the ceramic runner 52. The slot 78 could extend from the
inner diameter 61 of the ceramic runner 52 and partially traverse
the thickness of the ceramic runner 52 in the direction of the
outward facing sealing surface 60, as represented in FIG. 8b. The
anti-rotation key 89 could include a circular head as shown in FIG.
8b or a substantially rectangular head. The slot 78 is dimensioned
to avoid contact with the end and sides of the anti-rotation key
89, see FIGS. 8a and 8b, respectively. The anti-rotation key 89
could contact a side wall 102, the latter shown in FIG. 8b, along
the slot 78 when the ceramic runner 52 rotates relative to the
clamping ring 74. The degree of rotation before contact between the
anti-rotation key 89 and side wall 102 is determined by the
clearance therebetween, which is design dependent.
[0137] An annular seal ring 49 is circumferentially disposed about
the outward facing sealing surface 60 of the ceramic runner 52. The
annular seal ring 49 includes an inward facing sealing surface 59
which interacts with the outward facing sealing surface 60 to form
the circumferential sealing of the present invention. The annular
seal ring 49 is a ring-shaped element with or without segmentation.
In some embodiments, the inward facing sealing surface 59 could
physically contact the outward facing sealing surface 60 during
rotation of the ceramic runner 52 and shaft 57 to provide a contact
seal. In other embodiments, the inward facing sealing surface 59
and outward facing sealing surface 60 could be separated by a gap
to form a non-contact seal. In yet other embodiments, the outward
facing sealing surface 60 could include hydrodynamic pockets which
form a thin-film between inward and outward facing sealing surfaces
59, 60 during rotation of the ceramic runner 52.
[0138] The annular seal ring 49 resides within a seal housing 47
and is secured thereto via a support ring 50 and a retaining ring
51 or other like elements via methods and designs known within the
art. The annular seal ring 49 is rotationally stationary with
respect to the seal housing 47. As such, the annular seal ring 49
does not rotate with respect to the seal housing 47. The annular
seal ring 49 could move radially inward and outward to track radial
excursions of the ceramic runner 52. The seal housing 47 is secured
to a housing 48 comprising a turbine engine. Both seal housing 47
and housing 48 are shown in a generalized form for descriptive
purposes only and are not intended to limit the scope of the
claimed invention. Arrangement of the annular seal ring 49, seal
housing 47, and housing 48 about the ceramic runner 52 and shaft 57
generally defines a higher pressure side 81 and a lower pressure
side 82. The higher pressure side 81 could define the air or gas
side within a turbine engine. The lower pressure side 82 could
define the bearing or oil side within a turbine engine.
[0139] Referring again to FIG. 8a, the outward facing sealing
surface 60 along the ceramic runner 52 and annular surface 107 of
the carrier 91 are shown approximately radially aligned with the
outer diameter 100 of the shaft 57. However, it is understood that
outward facing sealing surface 60 and annular surface 107 could
extend above or be depressed below the outer diameter 100 in other
embodiments of the invention. In yet other embodiments, it is
possible for the outward facing sealing surface 60 and annular
surface 107 to move radially inward and outward with respect to the
outer diameter 100 during operation of a turbine engine.
[0140] Referring now to FIG. 9a, the circumferential seal 46 is
illustrated for descriptive purposes along an upper half of an
exemplary shaft 57 along a turbine engine rotatable about a
centerline 67. In this embodiment, a ceramic runner 52 is attached
to a carrier 91 to form a cartridge 90. The cartridge 90
facilitates assembly of components comprising the circumferential
seal 46 prior to attachment to a shaft 57. This approach simplifies
assembly and repair of a turbine engine.
[0141] The outer diameter 100 of the shaft 57 is shown including a
recess 98. The recess 98 could include one or more regions along
the shaft 57 each having a diameter smaller than the outer diameter
100. The exemplary shaft 57 has a recess 98 which includes a single
section to accommodate a locking ring 75 and a carrier 91, the
latter supporting a ceramic runner 52 and a clamping ring 74. The
clamping ring 74 and locking ring 75 are composed of materials
suitable for use within a turbine engine. Materials should be wear,
failure, and temperature resistant. Exemplary compositions include
metals, preferably compositions of steel. The locking ring 75
secures the carrier 91 with the various components described herein
to the shaft 57 about the recess 98. It is understood that the
recess 98 could include one or more sections as well as other
shapes and designs which facilitate attachment of elements required
to provide circumferential sealing along a shaft 57.
[0142] The interface between the outer diameter 100 of the shaft 57
and the outer diameter 62 of the recess 98 defines a first shoulder
55. The recess 98 could include additional shoulders depending on
the profile of the recess 98, although such features are optional
and design dependent. For example, the recess 98 could include
other shoulders each defined by a discontinuity where two outer
diameters differ.
[0143] The carrier 91 is a ring-shaped element with a flange 104
which extends perpendicular from one end an annular ring 105. In
some embodiments, a clearance fit is provided for assembly purposes
between the outer diameter 62 of the shaft 57 and inner diameter 85
of the carrier 91 so that the carrier 91 is slidable with respect
to the shaft 57. In other embodiments, an interference fit is
provided between the outer diameter 62 and the inner diameter 85
and the carrier 91 is heated to open the inner diameter 85 prior to
sliding the carrier 91 onto the shaft 57. The carrier 91 is then
cooled to fix the carrier 91 to the shaft 57. The flange 104 should
contact the shoulder 55 in addition to the annular ring 105
contacting the surface of the shaft 57. The carrier 91 is composed
of materials suitable for use within a turbine engine. Materials
should be wear, failure, and temperature resistant. Exemplary
compositions include metals, preferably compositions of steel with
a coefficient of thermal expansion comparable to that of the shaft
57 so that carrier 91 tracks the expansion and contraction of the
shaft 57.
[0144] The carrier 91 could likewise include one or more shoulders
along the annular ring 105. The interface between the annular
surface 107 along the carrier 91 and the outer diameter 106 of the
carrier 91 defines a first shoulder 92. The carrier 91 could also
include a first segment with an outer diameter 106 and a second
segment with an outer diameter 86. The outer diameter 106 could be
larger than the other outer diameter 86 so that a second shoulder
103 is provided at the discontinuity between the two outer
surfaces. A clearance fit could be provided between the outer
diameter 86 of the carrier 91 and inner diameter 83 along the
clamping ring 74 so that the clamping ring 74 is slidable with
respect to the carrier 91. The carrier 91 and clamping ring 74 are
secured to the shaft 57 via the locking ring 75. The locking ring
75 contacts both the clamping ring 74 and the end 93 of the carrier
91 as illustrate in FIG. 9a. The locking ring 75 includes threads
along its inner diameter 84 which engage a complementary thread
arrangement along the outer diameter 80 of the shaft 57. The force
applied by the locking ring 75 onto the carrier 91 and clamping
ring 74 should be sufficient to prevent relative motion with
respect to the shaft 57.
[0145] The ceramic runner 52 is a cylindrically-shaped or
sleeve-shaped element which is slid onto the shaft 57 during
assembly so as to circumscribe the carrier 91. The ceramic runner
52 is composed of a ceramic composition suitable for use within a
turbine engine. In preferred embodiments, the ceramic composition
should be wear, failure, and temperature resistant. Exemplary,
non-limiting compositions include silicon nitride and silicon
carbide.
[0146] The ceramic runner 52 has an inner diameter 61 which is
larger than the outer diameter 106 of the carrier 91 resulting in a
second annular gap 72 which avoids direct contact between the
ceramic runner 52 and carrier 91. The distance between a first end
53 and a second end 54 of the ceramic runner 52 is less than the
axial distance between the first shoulder 92 and second shoulder
103. The first end 53 is positioned adjacent to the first shoulder
92 so that a first annular gap 73 separates the first end 53 from
the first shoulder 92. The axial length of the first annular gap 73
is sized to accommodate a spring mechanism. The spring mechanism
provides no sealing functionality. Although spring mechanisms are
described herein, it is understood that such mechanisms could
include other non-sealing devices which at least resist compression
and are resilient. The second end 54 directly contacts the clamping
ring 74 so that the second end 54 is generally aligned with the
second shoulder 103.
[0147] In some embodiments, the spring mechanism could include a
plurality of compression springs 88 as represented in FIG. 9a and
generally described in FIGS. 7b and 7c. Each compression spring 88
is axially aligned along the direction of the shaft 57. The
compression springs 88 are further separately disposed about the
shaft 57 along the flange 104 of the carrier 91, as generally shown
in FIG. 8c, so as to communicate a biasing force 99 symmetrically
about the ceramic runner 52 in the axial direction. One end of each
compression spring 88 could reside within a complementary shaped
hole 94 within the flange 104 so that a portion of the compression
spring 88 extends into the first annular gap 73 with sufficient
length to contact the first end 53 along the ceramic runner 52. The
compression spring 88 could be mechanically fixed to the hole 94
via an interference fit or freely movable within the hole 94. The
compression springs 88 are preferred to be sufficiently long so
that each is partially compressed when assembled between the
carrier 91 and ceramic runner 52. Partial compression of the
compression spring 88 maintains a biasing force 99 onto the ceramic
runner 52 so that the second end 54 of the ceramic runner 52 is
biased toward and contacts the clamping ring 74. The biasing force
99 maintains contact between the second end 54 of the ceramic
runner 52 and the clamping ring 74 during operation of a turbine
engine, thereby avoiding separation thereof because of thermally
induced expansion and contraction of ceramic runner 52 and other
components within the engine. The biasing force 99 is also resists
rotational sliding between the ceramic runner 52 and clamping ring
74 at the second end 54. The compression springs 88 are partially
compressed at or below ambient conditions so as to allow for
further compression of the compression springs 88 during operation
of a turbine engine. This feature allows the compression springs 88
to expand and contract with expansion and contraction of the
ceramic runner 52 as the ceramic runner 52 and other components
heat and cool.
[0148] In other embodiments, the spring mechanism could be a single
annular spring 58, as represented in FIG. 8d. Exemplary annular
springs 58 include a wave spring or a compression spring or the
like which circumscribe the shaft 57 within the first annular gap
73 between the first end 53 of the ceramic runner 52 and first
shoulder 92 along the carrier 91. The length of the annular spring
58 in its uncompressed state requires the annular spring 58 to be
partially compressed when assembled between the ceramic runner 52
and carrier 91. The annular spring 58 is compressed by contact with
the first shoulder 92 at one side of the annular spring 58 and the
first end 53 at another side of the annular spring 58. In its
partially compressed state, the annular spring 58 communicates a
biasing force 99 axially onto the ceramic runner 52 thereby
pressing the ceramic runner 52 onto the clamping ring 74. The
biasing force 99 is preferred to maintain contact between the
second end 54 of the ceramic runner 52 and the clamping ring 74
during operation of a turbine engine, thereby avoiding separation
between the ceramic runner 52 and clamping ring 74 which could
occur because of thermally induced expansion and contraction of
components within the engine. The biasing force 99 also resists
rotational sliding motion between the ceramic runner 52 and the
clamping ring 74 at the second end 54. The annular spring 58 is
partially compressed at or below ambient conditions so as to allow
for further compression of the annular spring 58 during operation
of a turbine engine. This feature allows the annular spring 58 to
expand and contract with axial expansion and contraction of the
ceramic runner 52 as the ceramic runner 52 and other components
heat and cool.
[0149] In other embodiments, the first end 53 could directly
contact the first shoulder 92 and the spring mechanism, either the
annular spring 58 or the compression springs 88, is disposed
between the second end 54 and clamping ring 74, as shown in FIG.
9e. The biasing force 99 is directed toward the flange 104. The
spring mechanisms could be attached to the clamping ring 74 via in
a similar manner as the attachment to the flange 104 as described
in FIG. 9a. The first annular gap 73 is now disposed between the
clamping ring 74 and second end 54.
[0150] Referring again to FIG. 9a, the second annular gap 72
between the inner diameter 61 of the ceramic runner 52 and outer
diameter 106 of the carrier 91 is shown with a tolerance ring 70.
Although one tolerance ring 70 is shown and described, it is
understood that the second annular gap 72 could include one or more
such rings. The tolerance ring 70 is generally described as a
ring-shaped element with corrugations along an inward face or an
outward face and with a gap 87, the latter feature represented in
FIG. 6c. The tolerance ring 70 provides no sealing functionality.
When attached between the inner diameter 61 and outer diameter 106
along the gap 72, the tolerance ring 70 conforms to the bore and is
self-retaining thereby resisting rotational slip between the
ceramic runner 52 and carrier 91. The tolerance ring 70 could allow
for axial slippage so as to avoid stresses within the ceramic
runner 52. An exemplary tolerance ring 70 is the BN Series devices
sold by USA Tolerance Rings of Pennington, N.J. (United States).
The tolerance ring 70 maintains proper fit between the ceramic
runner 52 and carrier 91 by expanding circumferentially to the
radial clearance between the inner diameter 61 and outer diameter
106 by closing the gap 87. This functionality avoids radial
expansion of the ceramic runner 52, which could damage the runner
52. The tolerance ring 70 resides within an annular groove 63. The
annular groove 63 could be disposed along the inner diameter 61 of
the ceramic runner 52 in an arrangement similar to that shown in
FIG. 6a or along the outer diameter 106 of the carrier 91 as shown
in FIG. 9a. The depth of the annular groove 63 should allow
assembly of the ceramic runner 52 onto the carrier 91 and proper
placement of the tolerance ring 70 along the carrier 91 while
ensuring sufficient contact between the tolerance ring 70 and inner
and outer diameters 61, 106 for proper function of the tolerance
ring 70. The annular groove 63 should be at least as wide as the
tolerance ring 70, preferably providing a tolerance fit allowing
the tolerance ring 70 to be secured within the annular groove
63.
[0151] Referring again to FIG. 9a, the second annular gap 72
between the inner diameter 61 of the ceramic runner 52 and outer
diameter 106 of the carrier 91 is shown with a sealing ring 68. The
clamping ring 74 also includes a sealing ring 69 disposed along the
vertical surface at the interface with the ceramic runner 52. In
other embodiments, the seal ring 69 could be disposed within an
annular groove 66 between the carrier 91 and the ceramic runner 52
along the second annular gap 72 further between the clamping ring
74 and anti-rotation screw 96, as shown in FIG. 9d. Sealing rings
68, 69 could include devices known within the art, examples
including, but not limited to, multi-directional O-rings,
unidirectional spring-energized seals, high-temperature metallic
seal rings, or other comparable devices sold by the Parker Hannifin
Corporation located in North Haven, Conn. (United States) or other
suppliers. Other exemplary seals include those sold under the
Trademark OMNISEAL.RTM. by Saint-Gobain Performance Plastics
Corporation of Aurora, Ohio (United States). When assembled between
the inner diameter 61 and outer diameter 106 along the second
annular gap 72, the sealing ring 68 conforms to the bore thereby
further resisting rotational slip between the ceramic runner 52 and
carrier 91. The sealing ring 68 could allow for axial slippage so
as to avoid stresses within the ceramic runner 52. The sealing ring
69 conforms to the ring-shaped surfaces to further resist
rotational slip when assembled between the clamping ring 74 and the
ceramic runner 52. Each sealing ring 68, 69 resides within an
annular groove 64, 66, respectively. The annular groove 64 could be
disposed along the inner diameter 61 of the ceramic runner 52 in an
arrangement similar to that shown in FIG. 6a or along the outer
diameter 106 of the carrier 91 as shown in FIG. 9a. The depth of
each annular groove 64, 66 should be sufficiently deep so as to
allow assembly of the ceramic runner 52 onto the carrier 91 and
proper placement of the sealing rings 68, 69 along the carrier 91
while ensuring sufficient contact between the sealing ring 68 and
inner and outer diameters 61, 106, as well as the sealing ring 69
and the ceramic runner 52 and clamping ring 74, for proper function
of the sealing rings 68, 69. The grooves 64, 66 should be at least
as wide as the sealing rings 68, 69, preferably with a tolerance
fit allowing each sealing ring 68, 69 to be secured within the
respective annular groove 64, 66.
[0152] The sealing rings 68, 69 are disposed about the tolerance
ring 70, as represented in FIG. 9a. The sealing rings 68, 69 are
oriented so that the sealing direction 101 avoids or at least
minimizes oil and other contaminants within the higher and/or lower
pressure sides 81, 82 from entering the second annular gap 72 and
interacting with the tolerance ring 70. This feature minimizes
degradation to the performance of the tolerance rings 70 caused by
oil and other contaminants and further minimizes oil coking under
the ceramic runner 52.
[0153] Referring again to FIG. 9a, the carrier 91 further includes
at least one anti-rotation screw 96. The anti-rotation screw 96 is
attached or fixed to a threaded hole 95 along the carrier 91, as
represented in FIG. 9b, via techniques understood in the art so
that a portion of the anti-rotation screw 96 extends toward the
ceramic runner 52. The end of the anti-rotation screw 96 extending
from the carrier 91 could reside within a hole or slot 97 along the
ceramic runner 52. The hole or slot 97 could extend from the inner
diameter 61 of the ceramic runner 52 and partially traverse the
thickness of the ceramic runner 52 in the direction of the outward
facing sealing surface 60. The hole or slot 97 is dimensioned to
avoid contact with the end and side of the anti-rotation screw 96,
see FIGS. 9a and 9c, respectively. The anti-rotation screw 96 could
contact a side of the hole or slot 97 when the ceramic runner 52
rotates relative to the carrier 91. The degree of rotation before
contact between the anti-rotation screw 96 and side of the threaded
hole 95 is determined by the clearance therebetween which is design
dependent.
[0154] An annular seal ring 49 is circumferentially disposed about
the outward facing sealing surface 60 of the ceramic runner 52. The
annular seal ring 49 includes an inward facing sealing surface 59
which interacts with the outward facing sealing surface 60 to form
the circumferential sealing of the present invention. The annular
seal ring 49 is a ring-shaped element with or without segmentation.
In some embodiments, the inward facing sealing surface 59 could
physically contact the outward facing sealing surface 60 during
rotation of the ceramic runner 52 and shaft 57 to provide a contact
seal. In other embodiments, the inward facing sealing surface 59
and outward facing sealing surface 60 could be separated by a gap
to form a non-contact seal. In yet other embodiments, the outward
facing sealing surface 60 could include hydrodynamic pockets which
form a thin-film between inward and outward facing sealing surfaces
59, 60 during rotation of the ceramic runner 52.
[0155] The annular seal ring 49 resides within a seal housing 47
and is secured thereto via a support ring 50 and a retaining ring
51 or other like elements via methods and designs known within the
art. The annular seal ring 49 is rotationally stationary with
respect to the seal housing 47. As such, the annular seal ring 49
does not rotate with respect to the seal housing 47. The annular
seal ring 49 could move radially inward and outward to track radial
excursions of the ceramic runner 52. The seal housing 47 is secured
to a housing 48 comprising a turbine engine. Both seal housing 47
and housing 48 are shown in a generalized form for descriptive
purposes only and are not intended to limit the scope of the
claimed invention. Arrangement of the annular seal ring 49, seal
housing 47, and housing 48 about the ceramic runner 52 and shaft 57
generally defines a higher pressure side 81 and a lower pressure
side 82. The higher pressure side 81 could define the air or gas
side within a turbine engine. The lower pressure side 82 could
define the bearing or oil side within a turbine engine.
[0156] Referring again to FIG. 9a, the outward facing sealing
surface 60 along the ceramic runner 52 and annular surface 107 of
the carrier 91 are shown approximately radially aligned with the
outer diameter 100 of the shaft 57. However, it is understood that
outward facing sealing surface 60 and annular surface 107 could
extend above or be depressed below the outer diameter 100 in other
embodiments of the invention. In yet other embodiments, it is
possible for the outward facing sealing surface 60 and annular
surface 107 to move radially inward and outward with respect to the
outer diameter 100 during operation of a turbine engine.
[0157] The invention is applicable for use within a variety of
applications wherein sealing is required about a rotatable element.
One specific non-limiting example is a turbine engine including a
circumferential seal formed between a stationary annular seal and a
rotatable runner.
[0158] The description above indicates that a great degree of
flexibility is offered in terms of the present invention. Although
various embodiments have been described in considerable detail with
reference to certain preferred versions thereof, other versions are
possible. Therefore, the spirit and scope of the appended claims
should not be limited to the description of the preferred versions
contained herein.
* * * * *