UNITED TECHNOLOGIES CORPORATION

Patent Trials and Appeals Board

Aug 20, 2021

2021000981 (P.T.A.B. Aug. 20, 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.
15/424,927 02/06/2017 James D. Hill 95808US01;
67097-3573US1
2213
54549 7590 08/20/2021
CARLSON, GASKEY & OLDS/PRATT & WHITNEY
400 West Maple Road
Suite 350
Birmingham, MI 48009
EXAMINER
NG, HENRY
ART UNIT PAPER NUMBER
3741
NOTIFICATION DATE DELIVERY MODE
08/20/2021 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):
ptodocket@cgolaw.com
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
_______________

BEFORE THE PATENT TRIAL AND APPEAL BOARD
_______________

Ex parte JAMES D. HILL and FREDERICK M. SCHWARZ
_______________

Appeal 2021-000981
Application 15/424,927
Technology Center 3700
_______________

Before NATHAN A. ENGELS, JAMES W. DEJMEK, and
AMEE A. SHAH, Administrative Patent Judges.

DEJMEK, Administrative Patent Judge.

DECISION ON APPEAL
Appellant1 appeals under 35 U.S.C. § 134(a) from a Final Rejection of
claims 1, 8, and 20–23. The Final Office Action rejected then-pending
claims 1–4, 6, 8–10, 12, 14, 15, 17, and 20–23. See Final Act. 1, 5–16. In
an Amendment After Final (filed May 8, 2020), Appellant amended
independent claim 1 to incorporate the limitations of claims 2–4 and
canceled claims 2–4, 6, 9, 10, 12, 14, 15, and 17. See Amdt. 3–4. Appellant
had previously canceled claims 5, 7, 11, 13, 16, 18, and 19. See Amdt. 3–5

1 Throughout this Decision, we use the word “Appellant” to refer to
“applicant” as defined in 37 C.F.R. § 1.42 (2019). Appellant identifies
Raytheon Technologies Corporation as the real party in interest. Appeal
Br. 1.
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(filed Dec. 11, 2019). We have jurisdiction over the remaining pending
claims under 35 U.S.C. § 6(b).
We reverse and enter new grounds of rejection pursuant to our
authority under 37 C.F.R. § 41.50(b).

STATEMENT OF THE CASE
Introduction
Appellant’s disclosed and claimed invention generally relates to “a
mixing chamber for mixing two air sources in a gas turbine engine to utilize
as turbine cooling air.” Spec. ¶ 1. It is known that in a gas turbine engine,
components—particularly those in the turbine section—are subjected to high
temperatures. Spec. ¶¶ 4–5. Due to increased pressure in the turbine
section, it is desirable to use highly pressurized air to cool the components.
Spec. ¶ 5. According to the Specification, the “most pressurized air in the
gas turbine engine is downstream of a high pressure compressor and it is
typically hot.” Spec. ¶ 5. Thus, in order to use such highly pressurized air,
it must be cooled. Spec. ¶ 6. The Specification further describes that if the
air is cooled too much, it may not be effective under all conditions. Spec.
¶ 6. “Thus, it would be desirable to mix this cooling air with higher
temperature air.” Spec. ¶ 6.
In a disclosed embodiment, the Specification describes a gas turbine
engine comprising a compressor section and a turbine section. Spec. ¶ 7. A
housing surrounds the compressor and turbine sections. Spec. ¶ 7. In
addition, a mixing chamber is positioned radially outwardly of the housing.
Spec. ¶ 7; see also Fig. 2 (mixing chamber (116) positioned radially
outwardly from housing (117)). High pressure cooling air is tapped from a
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location downstream of the compressor and is passed through a heat
exchanger where it is cooled by lower pressure air passing across the heat
exchanger. Spec. ¶ 7. The cooled air is passed to the mixing chamber where
it is mixed with hotter air. Spec. ¶ 7. The mixed air “is returned into the
housing and utilized to cool at least the turbine section.” Spec. ¶ 7.
Claim 1 is illustrative of the subject matter on appeal and is
reproduced below with the disputed limitations emphasized in italics:
1. A gas turbine engine comprising:
a compressor section and a turbine section, said
compressor section having a last compressor stage;
high pressure cooling air tapped from a location
downstream of said last compressor stage and passed through a
heat exchanger;
lower pressure air passing across said heat exchanger to
cool said high pressure cooling air;
a housing surrounding said compressor section and said
turbine section and there being a space radially outwardly of said
housing, and a mixing chamber received in said space radially
outwardly of said housing, said mixing chamber connected to
receive said high pressure cooling air at a location downstream
of said heat exchanger, and further connected to receive air at a
temperature higher than a temperature of said high pressure
cooling air taken downstream of said heat exchanger;
mixed air from said mixing chamber returned into said
housing and utilized to cool at least said turbine section, said
mixing chamber having diverters to cause a change in a flow
direction of said high pressure cooling air and said air at a higher
temperature;
wherein said air at a higher temperature is tapped from a
common point as the high pressure cooling air which is sent into
said mixing chamber;
wherein said high pressure cooling air is tapped from a
diffuser section radially outwardly of a combustor located
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intermediate said compressor section and said turbine section;
and
wherein said mixed air passes through a compressor
diffuser downstream of said last compressor stage.

The Examiner’s Rejections2
1. Claims 1, 8, and 21–23 stand rejected under 35 U.S.C. § 103 as
being unpatentable over Seitzer et al. (US 2008/0112797 A1; May 15, 2008)
(“Seitzer”); Scoffone et al. (US 2017/0074106 A1; Mar. 16, 2017)
(“Scoffone”); and Klingels (US 6,612,114 B1; Sept. 2, 2003). Final
Act. 6–15; see also Ans. 3 (explaining that, due to Appellant’s amendments
incorporating, inter alia, the limitations of then-dependent claim 4 into
independent claim 1 after the Final Office Action, the rejection of claim 1 is
“identical to the rejection of claim 4 in the Final Rejection”).
2. Claim 20 stands rejected under 35 U.S.C. § 103 as being
unpatentable over Seitzer, Scoffone, Klingels, and Suciu et al.
(US 2015/0354465 A1; Dec. 10, 2015) (“Suciu”). Final Act. 16.

ANALYSIS3
Rejections of claims 1, 8, 20, and 21
In rejecting independent claim 1 (as amended by Appellant), the
Examiner relies on the combined teachings of Seitzer, Scoffone, and

2 In the Advisory Action (mailed May 21, 2020), the Examiner notes that
Appellant’s amendments have overcome the rejection under 35 U.S.C.
§ 112(b). See Advisory Act. 2.
3 Throughout this Decision, we have considered the Appeal Brief, filed
August 17, 2020 (“Appeal Br.”); the Reply Brief, filed November 23, 2020
(“Reply Br.”); the Examiner’s Answer, mailed October 5, 2020 (“Ans.”);
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Klingels. See Ans. 3. We begin our analysis with a brief review of the
relevant portions of these references.
Seitzer recognizes that in gas turbine engines, turbine components are
subjected to high temperatures and that the components may be cooled “by
bleeding a portion of the pressurized air from the compressor.” Seitzer ¶ 4.
Further, Seitzer describes that due to being exposed to varying temperature
conditions, the turbine components may thermally expand and contract,
which may affect the size of the turbine blade tip clearance with respect to
the turbine shroud. Seitzer ¶ 9. Seitzer discloses that active clearance
control (“ACC”) systems are known in which “relatively cool fan air or
relatively hot compressor bleed air, or a mixture thereof, are channeled to
the turbine case from which the shrouds are suspended,” thereby heating or
cooling the turbine case, as appropriate. Seitzer ¶ 14.

and the Final Office Action, mailed March 16, 2020 (“Final Act.”), from
which this Appeal is taken.
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Figure 2 of Seitzer is illustrative and is reproduced below:

Figure 2 of Seitzer illustrates a portion of a gas turbine engine
comprising an active clearance control system. Seitzer ¶¶ 20, 35. As shown
in Figure 2, high pressure cooling air (34a) is tapped from a location
downstream of a last compressor stage (18) and is passed through heat
exchanger (56) where the high pressure cooling air (34a) is cooled by bypass
fan air (34). Seitzer ¶ 38 (additionally describing that inlet circuit (58)
channels the high pressure cooling air (34a) to heat exchanger (56)). Cooled
air (34b) is passed from heat exchanger (56). Seitzer ¶ 39. Seitzer also
describes a compound distribution network comprising, inter alia, valves
(1, 2, and 3), which are controlled by controller (68). Seitzer ¶ 48. The
valves (1, 2, and 3) “control and regulate the flow through the various
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conduits of the distribution network.” Seitzer ¶ 47. More particularly the
first valve (1) controls the bypass flow of the hot compressor discharge air
(34a). Seitzer ¶ 49. The second valve (2) selectively controls or varies the
cooled compressor discharge air (34b) from heat exchanger (56) to turbine
blades (40). Seitzer ¶ 50. The third valve (3) selectively controls or varies
the flow of the cooled compressor discharge air (34b) to turbine case (48).
Seitzer ¶ 51.
In addition to describing various modes of operation in which one of
the valves is substantially fully open and the other two valves are
substantially closed, Seitzer also describes the two control valves (1, 3)
“control the relative amounts of the hot and cooled discharge air 34a, b.”
Seitzer ¶ 60 (emphasis added).
Scoffone generally relates to “mixing chambers for turbine wheel
space cooling.” Scoffone ¶ 1. In describing the mixing chamber, Scoffone
discloses that a first inlet tube delivers a first fluid and a second inlet tube
delivers a second fluid to the mixing chamber. Scoffone ¶ 22. Scoffone
describes the fluids can be purge flow or cooling flow, such as a gas (e.g.,
cooling air). Scoffone ¶¶ 22–23. Scoffone describes the “flow that enters
the mixing chamber 130 may exit the mixing chamber 130, and the baffle
plate 170 may assist in directing flow inside the mixing chamber 130 into
the exit hole(s) 210.” Scoffone ¶ 23. More specifically, regarding the baffle
plate, Scoffone teaches the baffle plate “may also enhance mixing within the
mixing chamber 130 due to a swirl of the first fluid and the second fluid.”
Scoffone ¶ 26; see also Scoffone, Fig. 4.
Klingels generally relates to “a cooling air system for reducing the
thermal loading on components in the turbine high-pressure region of gas
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turbines.” Klingels, col. 1, ll. 5–7. Klingels describes extracting the high-
pressure air to be cooled from the compressor section and passing the air
through a heat exchanger. Klingels, col. 1, ll. 18–21, col. 2, ll. 62–65.
Klingels further describes that the cooled air (i.e., discharged from the heat
exchanger) is guided through a control and mixing valve. Klingels, col. 4,
ll. 48–52. The mixing valve also has an input for the hotter air coming from
the extraction location. Klingels, col. 4, ll. 48–52. “The temperature of the
cooling air emerging from the control and mixing valve may be specifically
adjusted by mixing the cooled and the uncooled cooling air while varying
the quantity ratio.” Klingels, col. 4, ll. 52–55. Klingels further describes the
flow path of the mixed air (i.e., coming from the control and mixing valve)
is “through struts of the combustion chamber diffuser” and into the turbine
section. Klingels, col. 4, ll. 60–64.
In the Final Action, the Examiner finds Seitzer teaches, inter alia, that
high pressure cooling air is tapped from a diffuser section radially outwardly
of a combustor, the high pressure cooling air is passed through a heat
exchanger, and the output (cooled) air of the heat exchanger is passed to a
mixing chamber along with hotter air. See Final Act. 6–10. In support, the
Examiner provides an annotated version of Seitzer’s Figure 2, reproduced
below, to identify the housing and mixing chamber components in Seitzer.
See Final Act. 8.
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Figure 2 of Seitzer, as annotated by the Examiner, illustrates a cross-
section of a housing surrounding a compressor and turbine section and a
mixing chamber (illustrated as an unnumbered circle with an input of cooled
air (34b) from heat exchanger (56), via valve (3) and an input of high
pressure cooling air (34a), via valve (1)). See Final Act. 8.
In addition to the findings of Seitzer, the Examiner finds Scoffone
teaches use of diverters in a mixing chamber to “enhance mixing within the
mixing chamber” and Klingels teaches passing the mixed air from the
mixing chamber through a compressor diffuser downstream of the last
compressor stage. See Final Act. 8–9, 12–13.
Appellant disputes the Examiner’s findings that Seitzer teaches the
claimed mixing chamber. Appeal Br. 3–4; Reply Br. 1. Appellant argues
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that “[t]here is no description [(in Seitzer)] that the unnumbered circle is
anything other than a joint between two pipes.” Appeal Br. 3. Appellant
asserts there is no need for mixing within the unnumbered circle identified
by the Examiner as a mixing chamber because Seitzer describes
embodiments in which only one of the three valves is fully open while the
other two valves are substantially closed. Appeal Br. 4 (citing Seitzer
¶¶ 52–55). Appellant further argues that because there are not two flows
presented at the same time to the unnumbered circle (i.e., the mixing
chamber identified by the Examiner), there would be no need to modify
Seitzer’s so-called mixing chamber to include the diverters (i.e., baffling
plate) taught by Scoffone. Appeal Br. 4–5; Reply Br. 1. Still further,
Appellant argues that Seitzer fails to teach the high pressure cooling air is
tapped from a diffuser section radially outwardly of a combustor. Appeal
Br. 3–4.
We do not find these arguments persuasive of Examiner error. As
discussed above, we find Seitzer describes tapping high pressure cooling air
from a diffuser section radially outwardly of a combustor. See Seitzer ¶ 38,
Fig. 2 (illustrating high pressure cooling air passed to heat exchanger via
circuit (58)). In addition, as the Examiner explains, “the ‘diffuser section’
may be interpreted as the full-length plenum above combustor 20 of
Seitzer.” Ans. 4. We agree with the Examiner that this interpretation is
consistent with Appellant’s Specification and identification of housing
surrounding, inter alia, a combustor section. See Ans. 4 (citing Spec., Fig. 2
(117)). As such, the high pressure cooling air is tapped from a diffuser
section radially outwardly of the combustor.
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Further, we agree with the Examiner that the unnumbered circle in
Figure 2 of Seitzer teaches a mixing chamber. As discussed above, Seitzer
describes embodiments wherein air (34b) cooled by heat exchanger (56) via
valve (3) as well as hotter, high pressure cooling air (34a) via valve (1) are
input to the unnumbered circle (i.e., mixing chamber). See Seitzer ¶¶ 52–55,
60 (describing controlling relative amounts of each air input). We further
note that the embodiments of Seitzer identified by Appellant do not state that
only one valve is open while the others are closed. Rather, Seitzer describes
a relative setting in which the valves are “substantially” open or closed—
indicative of flow from a plurality of valves. See Seitzer ¶¶ 52–55. Because
we find Seitzer teaches a mixing chamber for mixing two different fluids
(i.e., air flows at different temperatures), we agree with the Examiner that it
would have been obvious to combine Scoffone’s teaching of a baffle plate
(i.e., diverter) with the mixing chamber of Seitzer “to enhance mixing,” as
taught by Scoffone. See Final Act. 8–9.
Appellant also asserts that Seitzer is intended to cool the turbine case
for clearance control. Appeal Br. 6. As such, Appellant argues there would
be no reason to modify the path of the air flow coming from the unnumbered
circle in Seitzer radially inwardly through the compressor diffuser, “as it
would defeat the purpose of cooling the turbine case.” Appeal Br. 6.
Moreover, Appellant argues that the Examiner’s reasoning that it is merely a
design choice as to how to route the air coming from the unnumbered circle
of Seitzer is unsupported. Appeal Br. 6–7.
In response, the Examiner explains that “having the airflow conduit
pass through the compressor diffuser as opposed to the turbine case 44, or
vice versa, would perform the same function and present no unexpected
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result.” Ans. 5. In addition, the Examiner finds that Appellant has not
demonstrated the criticality of passing the airflow conduit through the
compressor diffuser. Ans. 5.
To support a conclusion that a claim is directed to obvious subject
matter, i.e., that a feature is an obvious matter of design choice, the
Examiner must present a “convincing line of reasoning” as to why one of
ordinary skill in the art would have found the claimed feature to have been
obvious. Ex parte Clapp, 227 USPQ 972, 973 (BPAI 1985). Moreover,
when determining whether a rejection based on design choice is appropriate,
the Examiner must review the Specification and ascertain if the limitation in
question is disclosed as serving any advantage or particular purpose, or
whether it solves a stated problem. The Examiner also should explain the
reasoning used to determine that the prior art would have performed equally
as well as the claimed invention. These two steps help present the
aforementioned “convincing line of reasoning.” Clapp, 227 USPQ at 973.
Here, we agree with Appellant that the Examiner has not provided any
convincing line of reasoning why it would have been an obvious matter of
“design choice” to alter the routing of the mixed air flow of Seitzer through
the compressor diffuser, as taught by Klingels. Although there may be
reasons to make such a change (e.g., to alleviate the need to route spent
cooling air (34c) through the compressor diffuser where it is subsequently
routed to cool the turbine blades (see Seitzer ¶¶ 39, 42, Fig. 2)), such
reasoning is not on record before us. Nor has the Examiner proffered a
combination of incorporating the mixing chamber of Seitzer (as modified
with the diverters of Scoffone) to the system of Klingels. Although the
Board is authorized to reject claims under 37 C.F.R. § 41.50(b), no inference
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should be drawn when the Board elects not to do so. See Manual of Patent
Examining Procedure (“MPEP”) § 1213.02 (9th ed. Rev. 10.2019,
June 2020).
For the reasons discussed supra, we are persuaded of Examiner error.
Accordingly, we do not sustain the Examiner’s rejection of independent
claim 1. In addition, we do not sustain the Examiner’s rejections of claims
8, 20, and 21, which depend directly or indirectly therefrom.

Rejection of claims 22 and 23
Claims 22 and 23 are written in dependent claim format and recite
“wherein said swirl caused by said diverters provide efficient and thorough
mixing of said high pressure cooling air and said air at a higher
temperature.” Claim 22 purports to recite a further limitation on a gas
turbine engine “as set forth in claim 14.” Similarly, claim 23 purports to
recite a further limitation on a gas turbine engine “as set forth in claim 17.”
In the Amendment After Final, Appellant canceled claims 14 and 17
(among others). See Amdt. 3–4. Because claims 22 and 23 depend from
claims no longer pending, we pro forma reverse the Examiner’s rejection
under 35 U.S.C. § 103.

NEW GROUNDS OF REJECTION
Pursuant to our authority under 37 C.F.R. § 41.50(b), we enter new
grounds of rejection for claims 22 and 23 under 35 U.S.C. § 112(d) and
35 U.S.C. § 112(b).
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“[A] claim in dependent form shall contain a reference to a claim
previously set forth and then specify a further limitation of the subject matter
claimed.” 35 U.S.C. § 112(d).
As discussed above, claim 22 contains a reference to claim 14 and
claim 23 contains a reference to claim 17. Because the amendment
canceling claims 14 and 17 was entered by the Examiner, see Advisory
Act. 1, these claims are not “claim[s] previously set forth” for purposes of
35 U.S.C. § 112(d).
Accordingly, we newly reject claims 22 and 23 for failing to comply
with the provisions of 35 U.S.C. § 112(d).
In addition, the patent statute requires that claims “particularly point[]
out and distinctly claim[] the subject matter which the inventor or a joint
inventor regards as the invention.” 35 U.S.C. § 112(b).
Because claims 22 and 23 would incorporate by reference the
limitations of claims 14 and 17, respectively—but claims 14 and 17 have
been canceled—the scope of the subject matter encompassed by claims 22
and 23 cannot be determined without resorting to speculation. As such,
claims 22 and 23 are indefinite. See In re Wilson, 424 F.2d 1382, 1385
(CCPA 1970) (“If no reasonably definite meaning can be ascribed to certain
terms in the claim, the subject matter does not become obvious— the claim
becomes indefinite.”); see also In re Steele, 305 F.2d 859, 862 (CCPA
1962).
Accordingly, we newly reject claims 22 and 23 for failing to comply
with the provisions of 35 U.S.C. § 112(b).

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CONCLUSION
We reverse the Examiner’s decision rejecting claims 1, 8, 20, and 21
under 35 U.S.C. § 103.
We reverse, pro forma, the Examiner’s decision rejecting claims 22
and 23 under 35 U.S.C. § 103.
We enter a new ground of rejection rejecting claims 22 and 23 under
35 U.S.C. § 112(b).
We enter a new ground of rejection rejecting claims 22 and 23 under
35 U.S.C. § 112(d).

DECISION SUMMARY
Claim(s)
Rejected
35 U.S.C.
§
Reference(s)/
Basis
Affirmed Reversed New
Ground
1, 8,
21–23
103 Seitzer,
Scoffone,
Klingels
1, 8, 21–
23

20 103 Seitzer,
Scoffone,
Klingels,
Suciu
20
22, 23 112 Indefiniteness 22, 23
22, 23 112 Improper
Dependency
22, 23
Overall
Outcome
1, 8, 20–
23
22, 23

TIME PERIOD FOR RESPONSE
This decision contains a new ground of rejection pursuant to
37 C.F.R. § 41.50(b). Section 41.50(b) provides “[a] new ground of
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rejection pursuant to this paragraph shall not be considered final for judicial
review.” Section 41.50(b) also provides:
When the Board enters such a non-final decision, the appellant,
within two months from the date of the decision, must exercise
one of the following two options with respect to the new ground
of rejection to avoid termination of the appeal as to the rejected
claims:
(1) Reopen prosecution. Submit an appropriate
amendment of the claims so rejected or new Evidence relating to
the claims so rejected, or both, and have the matter reconsidered
by the examiner, in which event the prosecution will be
remanded to the examiner. The new ground of rejection is
binding upon the examiner unless an amendment or new
Evidence not previously of Record is made which, in the opinion
of the examiner, overcomes the new ground of rejection
designated in the decision. Should the examiner reject the
claims, appellant may again appeal to the Board pursuant to this
subpart.
(2) Request rehearing. Request that the proceeding be
reheard under §41.52 by the Board upon the same Record. The
request for rehearing must address any new ground of rejection
and state with particularity the points believed to have been
misapprehended or overlooked in entering the new ground of
rejection and also state all other grounds upon which rehearing
is sought.
Further guidance on responding to a new ground of rejection can be
found in the MPEP § 1214.01.
No time period for taking any subsequent action in connection with
this appeal may be extended. 37 C.F.R. § 1.136(a)(1)(iv); see 37 C.F.R.
§ 41.50(f).

REVERSED; 37 C.F.R. § 41.50(b)