GE AVIO S.r.l.

Patent Trials and Appeals Board

Sep 1, 2021

2021001833 (P.T.A.B. Sep. 1, 2021)

UNITED STATES PATENT AND TRADEMARK OFFICE
UNITED STATES DEPARTMENT OF COMMERCE
United States Patent and Trademark Office
Address: COMMISSIONER FOR PATENTS
P.O. Box 1450
Alexandria, Virginia 22313-1450
www.uspto.gov
APPLICATION NO. FILING DATE FIRST NAMED INVENTOR ATTORNEY DOCKET NO. CONFIRMATION NO.
15/348,657 11/10/2016 Daniele COUTANDIN 316450-US-3/GECV-1843 6106
122218 7590 09/01/2021
Dority & Manning, P.A. and GEC-Aviation
Post Office Box 1449
Greenville, SC 29602-1449
EXAMINER
MARIEN, ANDREW JAMES
ART UNIT PAPER NUMBER
3745
NOTIFICATION DATE DELIVERY MODE
09/01/2021 ELECTRONIC
Please find below and/or attached an Office communication concerning this application or proceeding.
The time period for reply, if any, is set in the attached communication.
Notice of the Office communication was sent electronically on above-indicated "Notification Date" to the
following e-mail address(es):
oc.prosecution@ge.com
usdocketing@dority-manning.com
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
____________________

BEFORE THE PATENT TRIAL AND APPEAL BOARD
____________________

Ex parte DANIELE COUTANDIN
____________

Appeal 2021-001833
Application 15/348,657
Technology Center 3700
____________

Before JENNIFER D. BAHR, CARL M. DEFRANCO, and
LISA M. GUIJT, Administrative Patent Judges.

GUIJT, Administrative Patent Judge.

DECISION ON APPEAL

STATEMENT OF THE CASE
Appellant1 seeks our review under 35 U.S.C. § 134(a) of the rejection
of claims 1–6, 10, and 14. We have jurisdiction under 35 U.S.C. § 6(b).
We AFFIRM.

1 We use the word “Appellant” to refer to “applicant” as defined in 37
C.F.R. § 1.42. Appellant identifies the General Electric Company as the real
party in interest. Appeal Br. 3.
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THE INVENTION
Appellant’s invention relates to “a gas turbine engine stage provided
with a labyrinth seal.” Spec. 1:7–9. Claims 1, 5, and 14 are the independent
claims on appeal. Claim 1, reproduced below, is illustrative of the subject
matter on appeal.
1. A gas turbine engine stage, the stage extending along a
rotation axis and comprising:
a static part;
a rotating part; and
a labyrinth seal arranged radially between said static part
and rotating part and comprising:
a) a layer of abradable material, which is arranged on said
static part, is continuous in the axial direction and, in an initial
assembly configuration, is radially delimited by a cylindrical
surface having a constant diameter; and
b) at least three tabs, that radially project from said rotating
part, are axially set apart from each other and end with respective
tips, directly facing said layer of abradable material in the radial
direction;
characterized in that said three tabs are constituted by:
first and second side tabs and
one intermediate tab, which is arranged in an intermediate
axial position between said side tabs and has a smaller radial
height than that of said side tabs;
the layer of abradable material is radially defined by a
shaped surface defining first and second seats, which have been
fretted by the tips of said first and second side tabs during
operation and are axially separated from each other by a step of
said shaped surface, wherein the first seat is positioned between
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the step and a forward portion of the abradable material which is
axially forward of the first side tab and which extends radially
inward past a tip of the first side tab towards the labyrinth seal
and the second seat is positioned between the step and an aft
portion of the abradable material which is axially aft of the
second side tab and which extends radially inward past a tip of
the second side tab towards the labyrinth seal; and
the tip of said intermediate tab is arranged at said step and
wherein the forward portion of the abradable material has a
height relative to a bottom of the first seat greater than a height
of the step and wherein the aft portion of the abradable material
has a height relative to a bottom of the second seat greater than a
height of the step.

THE REJECTIONS
The Examiner relies upon the following as evidence in support of the
rejections:
Name Reference(s) Date
Naudet US 4,604,030 Aug. 5, 1986
Mason US 5,096,376 Mar. 17, 1992
Nakano US 2011/0068539 A1 Mar. 24, 2011
Zeng US 2012/0043728 A1 Feb. 23, 2012
The following rejections are before us for review:
I. Claims 1, 4, 5, 10, and 14 stand rejected under 35 U.S.C.
§ 103 as unpatentable over Naudet, Nakano, and Mason.
II. Claims 2, 3, and 6 stand rejected under 35 U.S.C. § 103
as unpatentable over Naudet, Nakano, Mason,2 and Zeng.

2 We view the omission of Mason in the rejection of the dependent claims as
a typographical error, as the rejection cites Naudet and Nakano “as applied
to claims 1 and 5,” and Naudet and Nakano are applied in combination with
Mason in rejecting claims 1 and 5. Final Act. 13–14. Logically, the
dependency of claims 2, 3, and 6 on independent claims 1 and 5 necessitates
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OPINION
Rejection I
Regarding independent claim 1, the Examiner finds that Naudet
discloses, inter alia, a gas turbine engine stage with a labyrinth seal
comprising a layer of abradable material arranged on a static part and at least
three tabs radially projecting from a rotating part, as claimed. Final Act. 3–4
(citing, e.g., Naudet Fig. 1). The Examiner determines that Naudet does not
disclose that the intermediate tab has a smaller radial height than the side
tabs, and thus, also the differences in the opposing abraded material relative
to the height of the forward and aft portions as compared to a step, as
required by claim 1. Id. at 5–6.
The Examiner relies on Nakano disclosing, with reference to Figure 8,
an intermediate tab (i.e., fin 72) having a smaller radial height than the side
tabs (i.e., fins 72), and reasons that it would have been obvious to have
modified Naudet’s intermediate tab to have a smaller radial height than the
side tabs, as taught in Nakano, “to enhance seal performance.” Final Act. 6
(citing Nakano ¶ 18).
The Examiner relies on Mason for teaching that “teeth cut into the
abradable seal land during relative motions between the rotating and non-
rotating engine components,” such that “[i]t is known . . . to make a seal and
to reduce clearances [such] that the tab structure[] cut[s] into the abradable
material.” Id. at 6–7 (citing Mason 1:50–55). The Examiner reasons that it
would have been obvious “to have employ[ed] the teachings of Mason to

the inclusion of Mason to render obvious the subject matter of claims 2, 3,
and 6, which incorporate the limitations of claims 1 and 5.
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form seals with the teeth cutting into the abradable surface,” as applied to
Naudet, to allow for “less damage to the engine and seal.” Id. at 7.
Appellant argues that Naudet does not disclose forward and aft
portions having a greater height than a height of a step, or an intermediate
tab smaller than the first and second side tabs, but rather, Naudet discloses
three tabs having the same height. Appeal Br. 10; see also Reply Br. 3.
However, Appellant’s argument does not address the rejection as articulated
by the Examiner in that the Examiner relies on Nakano, not Naudet, for
disclosing these claim limitations and proposes modifying Naudet, in view
of Nakano (and in further view of Mason) to result in the claimed subject
matter. In other words, the Examiner responds correctly that non-
obviousness cannot be established by attacking references individually
where the rejection is based upon the teachings of a combination of
references. In re Merck & Co., Inc., 800 F.2d 1091, 1097 (Fed. Cir. 1986);
In re Keller, 642 F.2d 413, 425 (CCPA 1981). See Ans. 5.
Appellant also argues that “Naudet does not disclose an abradable
material having a shaped surface formed by the tips of the tabs.” Appeal Br.
10; see also Reply Br. 3.
We are not persuaded by Appellant’s argument.
First, Naudet discloses, with reference to a prior art labyrinth seal (i.e.,
without Naudet’s improvement) depicted in Figure 1, as relied on by the
Examiner, that “wear seal 9 . . . cooperates in known manner, with lips 10 of
a labyrinth seal rigid with the rotor, in order to reduce leakages resulting
from the pressure difference existing across the stator stage.” Naudet 3:37–
41 (emphases added). Second, the Examiner further relies on Mason for
teaching that a known manner of wearing the abradable material of a
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labyrinth seal is to have “[t]he teeth cut into the abradable seal land during
relative motions between the rotating and non-rotating engine components,”
such that “relative motion of the engine components can be accommodated
without deforming the seal labyrinth teeth or damaging the engine.” Mason
1:50–55. Indeed, even Appellant’s Specification admits, in the Background
of the Invention section, that
[l]abyrinth seals are widely used between the stator and the
rotor in aeronautical turbines, to limit the passage of gas streams
from a higher pressure cavity to a lower pressure one. As is
known, the labyrinth seal works by trying to create a narrow and
tortuous passage for the drawn gas flow. . . .
To maximize the sealing properties, labyrinth seals of the
known type have one part on the stator, defined by a layer of
abradable material . . . , and one part on the rotor, composed of a
series of radial tabs . . . .
. . . . The seal is configured such that, during operation, the
tip of each radial tab frets a corresponding seat within the layer
of abradable material, because of thermal expansion and of the
relative rotation.
Once the seats have been fretted, . . . [t]his configuration
helps to increase the head losses and thereby improve the sealing
properties, as it increases the tortuosity of the gas path and
narrows as much as possible the passage cross section for these
gases.
. . . .
This configuration also has the advantage that each radial
tab digs its own seat in the most appropriate way on the basis of
relative movements in each engine.
Spec. 1:11–2:22 (emphases added).
Thus, to the extent Naudet does not expressly disclose that the surface
of wear seal 9 is shaped by being abraded by lips 10, the Examiner’s reliance
on Mason for such a teaching is sufficient to render obvious this claimed
subject matter.
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Appellant further argues that “Nakano discloses teeth of differing
heights but does not disclose an abradable material with first and second
seats,” as required by claim 1. Appeal Br. 10; see also Reply Br. 3.
However, Appellant’s argument does not address the Examiner’s
combination, wherein Nakano’s fins 72 of differing heights are used to
modify Naudet’s lips 10 of a labyrinth seal, wherein the modified lips 10 of
Naudet fret wear seal 9, in a known manner as evidenced by Mason,
resulting in the claimed shaped surface on Naudet’s wear seal 9.
Next, Appellant argues that Nakano teaches that “the abradable layer
85 need not be employed” (quoting Nakano ¶ 168) and also that Nakano’s
“depressions and protrusions are pre-formed – not formed by tips of the
tabs.” Appeal Br. 10–11. However, Appellant’s argument that Nakano’s
abradable layer is optional or that, when employed, the abradable layer is
pre-formed with steps corresponding to the fins does not apprise us of error
in the Examiner’s finding that Nakano expressly discloses an intermediate
fin (or tab) having a smaller radial height than the side fins (or tabs). Nor
does Appellant apprise us of error in the Examiner’s reasoning that it would
have been obvious to a person of ordinary skill, at the time of the invention,
to have modified Naudet’s tabs of equal heights to have an intermediate tab
having a smaller radial height than the side tabs, as taught by Nakano, to
enhance seal performance, as Nakano specifically teaches that “depressions
and protrusions may be formed [on the turbine rotor’s surface] and the
length of the fins 71 may be adjusted in accordance therewith” because
“[b]y doing so, . . . the steam passing through moves in a zig-zag manner,
[such that] the sealing performance can be enhanced.” Nakano ¶ 167
(emphasis added); cf. Spec., supra (disclosing that known and widely used
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labyrinth seals use teeth to fret a corresponding abradable surface to increase
the tortuosity of the gas path).
Appellant further argues that “Nakano specifically tries to avoid
contact between the fins and the surfaces 83, 85, 87.” Appeal Br. 10–12
(citing Nakano ¶¶ 17, 22, 29, 35, 139, 156, 163); Reply Br. 3. Appellant
concludes that “Nakano teaches away from forming seats in an abradable
material using the tips of tabs/fins” and “Nakano applies the abradable
material to a pre-formed surface – the abradable material taking the shape of
the pre-formed surface as opposed to being formed during operation by the
tips of the tabs.” Appeal Br. 12–13.
The Examiner points out correctly that, although Nakano discloses a
preference for maintaining a gap between the fins and the opposing surface
such that the fins do not come into contact with the opposing surface,
Nakano also discloses that “the gap between the fins and the opposing
surface can be set so as to allow contact therebetween to some extent.” Ans.
6 (citing Nakano ¶ 42). Notably, a reference does not teach away, however,
if it merely expresses a general preference for an alternative invention but
does not “criticize, discredit, or otherwise discourage” investigation into the
invention claimed. In re Fulton, 391 F.3d 1195, 1201 (Fed. Cir. 2004). In
other words, we agree with the Examiner that Nakano does not teach away
from modifying the tabs of a labyrinth seal to have different heights to result
in a more tortuous path when the tabs fret uneven surfaces in the abradable
material of the opposing surface, in a labyrinth seal designed to perform as
known and widely used, as evidenced by Mason.
Finally, Appellant argues that Mason does not disclose the claimed
forward and aft portions having a greater height than a seat in the shaped
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surface formed by the tips fretting the abradable surface material, as required
by claim 1, or further, that “[o]ne skilled in the art would not interpret the
Mason reference [as] teaching the use of relative motions between rotating
and nonrotating engine components for a predetermined structure.” Appeal
Br. 13; Reply Br. 3–4. The Examiner responds that “Mason teaches that the
teeth cut into abradable material during relative motion between
components” and Mason is relied upon for teaching “the intended purpose of
the abradable material of the seals and further explain how the seals work.”
Ans. 7. The Examiner explains that the Examiner’s combination, which
involves modifying Naudet’s tabs, in view of Nakano, results in the claimed
“seat and step structure during operation” (id.), in view of Mason’s teaching
that tabs are known to be used to form a shaped surface in abraded material.
Appellant’s argument does not apprise us of error in the Examiner’s finding
relative to Mason or reasoning in view of Mason.
Accordingly, we sustain the Examiner’s rejection of independent
claim 1. Appellant relies on the same arguments for the patentability of
independent claims 5 and 14, and also dependent claims 4 and 10, as relied
on for the patentability of independent claim 1 supra. Therefore, for
essentially the same reasons as set forth supra, we also sustain the
Examiner’s rejection of independent claims 5 and 14, and dependent claims
4 and 10. Appeal Br. 14–16.
Rejection II
Appellant relies on the same arguments for the patentability of
dependent claims 2, 3, and 6 as relied on for the patentability of independent
claim 1 supra and as also applied to independent claim 5. Appeal Br. 16.
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Therefore, for essentially the same reasons as set forth supra, we also sustain
the Examiner’s rejection of dependent claims 2, 3, and 6.
CONCLUSION
The Examiner’s decision rejecting claims 1–6, 10, and 14 is affirmed.
DECISION SUMMARY
In summary:
Claim(s)
Rejected
35
U.S.C.
§
Reference(s)/Basis Affirmed Reversed
1, 4, 5, 10,
14
103 Naudet, Nakano, Mason 1, 4, 5, 10,
14

2, 3, 6 103 Naudet, Nakano, Mason,
Zeng
2, 3, 6
Overall
Outcome
1–6, 10, 14

TIME PERIOD FOR RESPONSE
No time period for taking any subsequent action in connection with
this appeal may be extended under 37 C.F.R. § 1.136(a). See 37 C.F.R.
§ 1.136(a)(1)(iv).
AFFIRMED