Ex Parte Meier et al

Patent Trial and Appeal Board

Aug 28, 2017

12162307 (P.T.A.B. Aug. 28, 2017)

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.
12/162,307 06/30/2009 Reinhold Meier 011235.60480US 9818
23911 7590
CROWELL & MORING LLP
INTELLECTUAL PROPERTY GROUP
P.O. BOX 14300
WASHINGTON, DC 20044-4300
EXAMINER
EDGAR, RICHARD A
ART UNIT PAPER NUMBER
3745
NOTIFICATION DATE DELIVERY MODE
08/30/2017 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):
edocket @ crowell. com
tche @ crowell. com
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
BEFORE THE PATENT TRIAL AND APPEAL BOARD
Ex parte REINHOLD MEIER, CLAUS MUELLER,
KARL-HEINZ DUSEL and ROLAND HUTTNER
Appeal 2016-001037
Application 12/162,307
Technology Center 3700
Before STEVEN D.A. McCARTHY, CHARLES N. GREENHUT and
ERIC C. JESCHKE, Administrative Patent Judges.
McCARTHY, Administrative Patent Judge.
DECISION ON APPEAL
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1 The Appellants identify the real party in interest as MTU Aero
Engines AG, formerly known as MTU Aero Engines GmbH, of Munich,
Germany.
STATEMENT OF THE CASE
The Appellants1 appeal under 35 U.S.C. § 134(a) from the Examiner’s
decision finally rejecting claims 18, 28, 36 and 41 under pre-AIA 35 U.S.C.
§ 103(a) as being unpatentable over Tuffs (US 2004/0265120 Al, publ. Dec.
30, 2004) in view of Antonellis (US 4,526,508, issued July 2, 1985) and
European Powder Metallurgy Ass’n, Additive Manufacturing Technology
(“Promoting Powder Metallurgy Tech.”), or, in alternative, over Antonellis
in view of Tuffs and Promoting Powder Metallurgy Tech.', and claims 35,
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Application 12/162,307
37, 38, 40, 42 and 43 under § 103(a) as being unpatentable over Tuffs in
view of Antonellis, Promoting Powder Metallurgy Tech, and Otto (US
4,368,074, issued Jan. 11, 1983), or, in alternative, over Antonellis in view
of Tuffs, Promoting Powder Metallurgy Tech, and Otto. (See Final Office
Action, mailed Jan. 9, 2015, at 4 & 7). We have jurisdiction under 35
U.S.C. § 6(b).
We AFFIRM.
THE CLAIMED SUBJECT MATTER
The claims on appeal are directed to producing guide blade segments
for gas turbines. The background of the claimed subject matter is best
derived from the teachings of the prior art.
In a gas turbine engine, “hot, high pressure gases are expanded
through [a] turbine section to produce useful work.” (Antonellis, col. 1,11.
22 & 23). The turbine section typically includes a rotor assembly and a
stator assembly. The rotor assembly includes rotor discs mounted on a
common axle that extends in the direction of the surrounding gas flow.
Rotor blades project radially outwardly from each disc. The rotor blades are
symmetrically arranged about the axle and are angled so that the expanding
gases flowing axially over both the rotor discs and axle turn the rotor blades,
thereby turning the rotor discs and the axle to produce useful work. (See
Antonellis, col. 1,11. 30-36).
The stator assembly shapes the flow of the expanding gases so as to
increase the amount of energy transferred by the flow to the rotor blades.
The stator assembly includes an outer casing that confines the flow to the
vicinity of the rotor blades. The outer casing mounts symmetrically-
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Appeal 2016-001037
Application 12/162,307
arranged, radially inwardly projecting stator vanes or guide blades. The
guide blades direct the expanding gases against the rotor blades at angles
favorable to extracting useful work. (See Antonellis, col. 1,11. 38—45).
Because the rotor assembly turns while the stator assembly remains
stationary, a radial clearance must be left between the guide blades and the
rotor assembly. The ability of the guide blades to shape the flow of the
expanding gases depends on the bulk of the expanding gases flowing
between the guide blades rather than through the radial gap between the
guide blades and the rotor assembly. (See Antonellis, col. 1,11. 45—53). For
this reason, the radial gap between the guide blades and the rotor assembly
must be sealed.
As explained in the Specification:
Assigned to the radially inner end of. . . each guide blade of a
guide blade segment is an inner cover band, wherein, in order to
guarantee an optimal degree of efficiency of a gas turbine, [the]
radially inner gap between the inner cover band of the guide
blades and the rotor of the gas turbine needs to be sealed. Sealing
the radially inner gap between the inner cover band and the rotor
of the gas turbine is accomplished using what is commonly called
an inner air seal, wherein, for this purpose, sealing elements are
assigned to the inner band of the guide blade segments. These
sealing elements can be designed as honeycomb seals.
(Spec., para. 3).
The Specification explains that conventional sealing elements were
manufactured separately from the guide blades and then soldered to the
blades. According to the Specification, the soldered joints between the
guide blades and the sealing elements represented thermo-mechanical weak
points; and the separate manufacture, and subsequent joining, of the guide
blades and sealing elements required unnecessary manufacturing effort.
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Application 12/162,307
(See Spec., para. 4). The Appellants seek to address these problems by
manufacturing the sealing element as an integral part of the inner cover
band. (See Spec., para. 5). At least the first of the problems identified by
the Appellants, the potential thermo-mechanical weakness of soldered or
brazed joints, was recognized, at least in general terms, in the prior art:
Tuffs teaches that “problems may be experienced with the brazed joints”
(see Tuffs, para. 4); and suggests the substitution of an integral structure for
a brazed joint so that there is “no possibility of the [honeycomb seal]
becoming detached from [a] substrate” (see Tuffs, para. 77).
Claims 18 and 28 are independent. Claim 28 recites:
28. A method for producing a guide blade segment of a
gas turbine, wherein the guide blade segment has a guide blade
and an inner cover band on a radially inner end of the guide
blade, comprising the step of:
integrally forming a honeycomb seal and the inner cover
band of the guide blade segment by building up the honeycomb
seal and the inner cover band integrally in layers in a generative
manufacturing method consisting of electron-beam melting or
laser melting.
ISSUE
The Appellants argue that it would not have been obvious to combine
the teachings of Antonellis, Tuffs and Promoting Powder Metallurgy Tech.
because Tuffs teaches an open cell structure 38 incorporated into a seal
structure 30, whereas Antonellis teaches a seal land 94 fabricated from a
honeycomb material, supported by an inner end 48 of a guide blade, that is,
the stator vane 26. (See App. Br. 3 & 4; Reply Br. 1—3). The sole issue in
this appeal is:
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Would it have been obvious in view of the teachings of Tuffs to have
modified the attachment of the seal land 94 of Antonellis to the inner end 48
of the stator vane 26 as proposed by the Examiner?
FINDINGS OF FACT
The record supports the following findings of fact (“FF”) by a
preponderance of the evidence.
Tuffs
1. Tuffs describes a turbine seal segment 20 for a high pressure
turbine stage 22 of a gas turbine engine 10. (See Tuffs, paras. 47 and 50).
Each turbine seal segment 20 takes the form of an arc-shaped sealing
element. The turbine seal segments 20 together form a substantially
cylindrical seal segment ring that encases the rotating turbine blades. (See
Tuffs, para. 50). The tips 3d of the turbine blades 22 cooperate with the
turbine seal segments 20, as depicted in Figure 2 of Tuffs, to restrict the flow
of expanding gases through the radial gap between the turbine blades and the
seal segment ring.
2. Tuffs teaches that the turbine seal segments 20 should be
abradable, to allow the tips 3d of the turbine blades 22 to wear away the seal
segments to optimum sizes and shapes. (See Tuffs, para. 3). Tuffs teaches
that conventional abradable seal segments were fabricated by brazing a
honeycomb material, that is, an open cell structure, in place on a substrate;
and subsequently filling the cells of the honeycomb material with metal
powder. (See Tuffs, para. 3).
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3. As mentioned earlier, Tuffs teaches that “problems may be
experienced with the brazed joints” between the honeycomb material and the
substrates (see Tuffs, para. 4); and suggests the substitution of an integral
structure for a brazed joint so that there is “no possibility of the open cell
structure . . . becoming detached from the substrate” (see Tuffs, para. 77).
4. Tuffs teaches using powder fed laser welding to deposit the
honeycomb material, that is, the open cell structure 38, on the substrate 54.
(See Tuffs, paras. 7, 55 & 56; see also Ans. 5).
5. As the Appellants correctly point out, Tuffs does not teach
fabricating the honeycomb material on an inner cover ring of a stator vane or
guide blade.
Antonellis
6. Antonellis describes a gas turbine engine 10 including a turbine
section 16. The turbine section 16 includes a rotor assembly 20 and a stator
assembly 22. (See Antonellis, col. 3,11. 46—55 & Fig. 1). The stator
assembly 22 includes radially inwardly projecting guide blades or stator
vanes 26, 28, 30. (See Antonellis, col. 3,11. 57—59; & Figs. 1 & 2).
7. As depicted in Figure 2 of Antonellis, an inner end 48 of the
stator vane 26 mounts an annularly extending seal land 94 fabricated from a
honeycomb material. The seal land 96 cooperates with annularly extending
knife edge elements 94 projecting radially outwardly from the rotor
assembly 20 to provide a labyrinth seal 98 between the rotor assembly 20
and the stator assembly 22. (See Antonellis, col. 4,11. 51—55).
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8. Although Antonellis teaches that the seal land 94 is “attached”
to the inner end 48 of the stator vane 26 (see Antonellis, col. 4,11. 51—53),
Antonellis does not describe the manner of attachment further.
Promoting Powder Metallurgy Tech, and Otto
9. We adopt and incorporate by reference the Examiner’s
unchallenged findings regarding the teachings of Promoting Powder
Metallurgy Tech, on pages 5 and 6 of the Final Office Action, mailed
January 9, 2015.
10. We adopt and incorporate by reference the Examiner’s
unchallenged findings regarding the teachings of Otto on page 7 of the Final
Office Action.
ANALYSIS
Antonellis describes an annularly extending seal land 94 that is
fabricated from a honeycomb material and attached to an inner end 48 of a
stator vane 26. (See FF 7 and 8). Antonellis does not appear to describe
how the seal land 94 is attached to the inner end 48 of the stator vane 26.
Tuffs criticizes conventional brazed joints between open cell foil honeycomb
and metal substrates. (See FF 3). Tuffs teaches the substitution of an
integral structure for a brazed joint so that there is “no possibility of the open
cell structure . . . becoming detached from the substrate” (see FF 3, quoting
Tuffs, para. 77); and suggests instead fabricating such open cell honeycomb
foil material by deposition on a metal substrate using powder fed laser
welding. Promoting Powder Metallurgy Tech, suggests that selective laser
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melting would have been a known substitute for powder fed laser welding.
(See FF 9, incorporating by reference Final Act. 5 & 6).
Regardless of the specific sealing structure described by Tuffs, it
would have been obvious from Tuffs’ teachings regarding the advantages of
powder fed laser welding in a turbine engine environment; and from
Promoting Powder Metallurgy Tech.’s suggestion that selective laser
melting might be substituted for powder fed laser welding, to have used a
deposition technique such as selective laser melting to fabricate an open cell
honeycomb foil seal land on the inner end (that is, the inner cover band) of
the guide blade described by Antonellis. (See Final Act. 6 & 7). We sustain
the rejection of claims 18, 28, 36 and 41 under § 103(a) as being
unpatentable over Antonellis in view of Tuffs and Promoting Powder
Metallurgy Tech. Because the Appellants argue the patentability of claims
35, 37, 38, 40, 42 and 43 solely on the basis of perceived deficiency in the
combined teachings of Antonellis, Tuffs and Promoting Powder Metallurgy
Tech, as applied to the subject matter of independent claims 18 and 28, we
also sustain the rejection of claims 35, 37, 38, 40, 42 and 43 under § 103(a)
as being unpatentable over Antonellis in view of Tuffs, Promoting Powder
Metallurgy Tech, and Otto.
We do not sustain the rejection of claims 18, 28, 36 and 41 under §
103(a) as being unpatentable over Tuffs in view of Antonellis and
“Promoting Powder Metallurgy Tech',” or the rejection of claims 35, 37, 38,
40, 42 and 43 under § 103(a) as being unpatentable over Tuffs in view of
Antonellis, Promoting Powder Metallurgy Tech, and Otto. The Examiner
has not articulated a persuasive reason why one of ordinary skill in the art,
familiar with the teachings of Antonellis, would have modified Tuffs
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structure by replacing the seal segment 30 described by Tuffs with a seal
located on the radially inner end of a guide blade. (See App. Br. 3 & 4;
Reply Br. 1 & 2).
DECISION
We AFFIRM the Examiner’s decision rejecting claims 18, 28, 35—38
and 40-43.
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).
AFFIRMED
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