ClearSign Combustion Corporation

Patent Trials and Appeals Board

Jul 27, 2020

2019005331 (P.T.A.B. Jul. 27, 2020)

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.
15/091,906 04/06/2016 DOUGLAS W. KARKOW 2651-253-03 6122
134647 7590 07/27/2020
Launchpad IP, Inc.
914 164th St. SE
Suite B-12 #433
Mill Creek, WA 98012
EXAMINER
LAU, JASON
ART UNIT PAPER NUMBER
3762
NOTIFICATION DATE DELIVERY MODE
07/27/2020 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):
docket@launchpadip.com
renise@launchpadip.com
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
BEFORE THE PATENT TRIAL AND APPEAL BOARD
Ex parte DOUGLAS W. KARKOW, JOSEPH COLANNINO, ROBERT E.
BREIDENTHAL, and CHRISTOPHER A. WIKLOF
Appeal 2019-005331
Application 15/091,906
Technology Center 3700
Before CHARLES N. GREENHUT, MICHAEL J. FITZPATRICK, and
MICHELLE R. OSINSKI, Administrative Patent Judges.
GREENHUT, Administrative Patent Judge.
DECISION ON APPEAL
STATEMENT OF THE CASE
Pursuant to 35 U.S.C. § 134(a), Appellant1 appeals from the
Examiner’s decision to reject claims 1–25. See Final Act. 1. We have
jurisdiction under 35 U.S.C. § 6(b).
We REVERSE.

1 We use the word Appellant to refer to “applicant” as defined in 37 C.F.R.
§ 1.42. Appellant identifies the real party in interest as ClearSign
Combustion Corporation, having an address at 12870 Interurban Avenue
South, Seattle, WA 98168. Appeal Br. 3.
Appeal 2019-005331
Application 15/091,906

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CLAIMED SUBJECT MATTER
The claims are directed to a pre-mixed fuel burner with perforated
flame holder. Claim 1, reproduced below, is illustrative of the claimed
subject matter:
1. A combustion system, comprising:
a premix chamber configured to receive an oxidant and a
fuel, wherein the premix chamber is configured to provide an
oxidant-fuel mixture into a chamber volume; and
a perforated reaction holder positioned within the chamber
volume, wherein the perforated reaction holder is displaced from
the premix chamber and aligned with the premix chamber to
receive the oxidant-fuel mixture;
wherein the perforated reaction holder carries a
combustion reaction while at least part of the oxidant-fuel
mixture combusts;
wherein the premix chamber is configured to receive an
oxidant inlet extending at least partially into the premix chamber
and a fuel inlet at least partially carried within the oxidant inlet;
and
wherein the oxidant inlet is terminated, inside the premix
chamber, at an angle that directs incoming fuel and oxidant away
from an outlet of the premix chamber and causes the fuel stream
and the oxidant stream to mix in a pair of counter-rotating
vortices within the premix chamber mix prior to passing through
the outlet.
Appeal 2019-005331
Application 15/091,906

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REFERENCES
The prior art relied upon by the Examiner is:
Name Reference Date
Stack US 3,155,142 Nov. 3, 1964
Wojcieson US 4,443,182 Apr. 17, 1984
Taylor US 5,326,257 July 5, 1994
Mauzey US 2004/0058290 A1 Mar. 25, 2004
Leinemann US 2006/0008755 A1 Jan. 12, 2006
Krauklis US 2006/0292510 A1 Dec. 28, 2006
Borissov US 2012/0064465 A1 Mar. 15, 2012
REJECTIONS
Claim 1 is rejected under 35 U.S.C. § 103 as being unpatentable over
Taylor and Borissov. Final Act. 2.
Claims 1–3, 5, 6, 8, 10–13, 16, 19, 24, and 25 are rejected under
35 U.S.C. § 103 as being unpatentable over Stack, Taylor, and Borissov.
Final Act. 3.
Claim 4 is rejected under 35 U.S.C. § 103 as being unpatentable over
Stack, Taylor, Borissov, and Krauklis. Final Act. 7.
Claims 7 and 9 are rejected under 35 U.S.C. § 103 as being
unpatentable over Stack, Taylor, Borissov, and Leinemann. Final Act. 7.
Claims 14, 15,2 20, 22, and 23 are rejected under 35 U.S.C. § 103 as
being unpatentable over Stack, Taylor, Borissov, and Wojcieson. Final Act.
9.

2 Even though the Examiner failed to include reference to claim 15 in the
heading for this rejection (see Final Act. 9), the Examiner makes reference
to this claim within the body of the rejection (see id. at 10). We consider the
failure to include reference to claim 15 in the heading a typographical error,
and therefore, we list claim 15 as being subject to this ground of rejection.
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Application 15/091,906

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Claims 17, 20, and 21 are rejected under 35 U.S.C. § 103 as being
unpatentable over Stack, Taylor, Borissov, and Mauzey. Final Act. 11.
Claim 18 is rejected under 35 U.S.C. § 103 as being unpatentable over
Stack, Taylor, Borissov, Mauzey, and Wojcieson. Final Act. 13.
OPINION
A central issue in this appeal is the Examiner’s reliance on certain
chambers or portions of chambers in Taylor, Borissov, and Stack as the
recited “premix chamber” as recited in each of independent claims 1 and 16,
the only independent claims before us. Reply Br. 2–3, 5.
There does not appear to be any dispute that a “premix chamber” in
this context must at the very least be associated with the mixing of fuel and
oxidant. Irrespective of general or art-specific definitions, the language of
claim 1 itself goes further, requiring the “fuel inlet” to be “carried within the
oxidant inlet,” which itself must be “extending at least partially into,” and
“terminated[] inside,” “the premix chamber,” “within” which “the fuel
stream and the oxidant stream . . . mix.” Claim 1. Claim 16 makes similar
requirements of the premix chamber in the contexts of the following recited
method steps:
receiving an oxidant in a premix chamber from an oxidant
inlet extending at least partially into the premix chamber;
receiving a hydrocarbon fuel into the premix chamber
from a fuel inlet at least partially carried within the oxidant inlet;
mixing the hydrocarbon fuel in the premix chamber, to
generate an oxidant-fuel mixture . . .
Taylor and Stack are similar in that, contrary to the language of claims
1 and 16, premixing of the fuel and oxidizer appears to occur at some
undisclosed location. Taylor illustrates the air and fuel supply 40
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Application 15/091,906

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schematically. From the schematic illustration alone, it could be argued that
it is not clear if the box 40 and the line connecting box 40 to conduit 42
represent premixed, or separate streams of, fuel and air. The Examiner
appears to believe the latter is a possibility based on the Examiner’s
proposed modification to Taylor to replace box 40 and its associated
connection line with the separate streams described in Borissov. See Ans.
17–18 (annotating Taylor Fig. 1 with what appears to be a combination of
modified versions of Figures 4 and 7 of Borissov). However, as Appellant
points out Taylor consistently refers to delivering a “premixed supply of air
and fuel into the lower interior region 22 via conduit 42. Appeal Br. 21
(citing Taylor col. 4, ll. 6 et seq.); see also Taylor col. 4, ll. 15–16. Because
the air and fuel in Taylor are mixed prior to entering plenum 48 in Taylor, it
is not reasonable in this context for the Examiner to rely on plenum 48 as the
recited “premix chamber.” See Final Act. 2. With respect to Stack, the
Examiner’s reliance on the space defined by diffuser plate 15 on its
lowermost end (when viewed in Figure 2 of Stack), feed plate 12 on its
uppermost end and the internal bore of housing portion 13b, suffers from a
similar shortcoming because Stack states: “A pipe 14 is suitably provided
for introduction of combustible gas-air mixtures to the feed plate 12.” Stack
col. 3, ll. 37-38. As Appellant points out, this passage, along with the
following passage encouraging stratification prevention, strongly suggests
that fuel and oxidant are mixed prior to arriving at the space the Examiner
relies upon as the recited “premix chamber.” Appeal Br. 26 (citing Stack col.
3, ll. 37 et seq.).
The Examiner also points to Borissov as disclosing a “premix
chamber.” Final Act. 3, 4. There is nothing wrong, per se, with pointing out
Appeal 2019-005331
Application 15/091,906

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a reference teaches subject matter for which the Examiner has already cited
another reference, contrary to Appellant’s suggestion. Appeal Br. 25.
However, in this instance, Appellant’s confusion in understanding the
precise position taken by the Examiner in the Final Action is understandable.
In any case, the Examiner’s position in this regard appears to be clarified in
conjunction with the annotated Taylor Figure on page 18 of the Answer
mentioned above and the similar annotation of Figure 2 of Stack illustrated
on page 23 of the Answer.
The Examiner indicates that it is the region of Borissov’s chamber
within swirler nozzle or a diverging outlet 51, referred to as cone 51 that
constitutes a “premix chamber” according to claim 1 and, by implication,
claim 16. Ans. 16–17.
First, although not necessarily controlling, “[p]rior art references may
be ‘indicative of what all those skilled in the art generally believe a certain
term means . . . [and] can often help to demonstrate how a disputed term is
used by those skilled in the art.’ Accordingly, the PTO’s interpretation of
claim terms should not be so broad that it conflicts with the meaning given
to identical terms in other patents from analogous art.” In re Cortright, 165
F.3d 1353, 1358 (Fed. Cir. 1999) (citation omitted). Here, in the embodiment
relied on by the Examiner, Borissov never refers to the “upstream end”
(Ans. 16) of the combustion chamber 33 itself as being a chamber. Nor does
Borissov refer to a presumably relatively small region near or within nozzle
or cone 51 as a chamber. Borissov was clearly aware of the word “chamber”
and knew that it took some identifiable boundaries to create one as
evidenced by Borissov’s reference to combustion chamber 433 being
separated by diaphragm 477 into a “main combustion chamber 433a and a
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pre-chamber 433b” (emphasis added) when describing the alternate
embodiment depicted in Figure 12 of Borissov.3 Borissov para. 104.
Even assuming that the region within cone 51 is reasonably regarded
as a chamber, there is no dispute that the “pre” in “premix” refers to mixing
that occurs before combustion. Borissov neither illustrates nor discloses the
precise location of ignition in the embodiment depicted in Figures 1–8.
However, Borissov discloses an “igniter (not shown in the Figures for this
embodiment) positioned proximate the 10 local circulation region LCR
and/or the fuel nozzle 49 to initiate combustion.” Borissov para. 65. Nozzle
49 is depicted in Figures 1 and 4 of Borissov on the upstream end of the
region within cone 51 which the Examiner relies on as being the “premix
chamber.” Of course, if combustion occurs proximate nozzle 49 sufficiently
upstream of cone 51, there is clearly little or no premixing of fuel and
oxidant within cone 51. The Examiner posits that Borissov’s mention of a
possible igniter location as proximate local circulation region LCR places
the igniter at the downstream end of cone 51. Ans. 16–17. However, even if
this were the case, it is not clear from Borissov’s disclosure what level and
what type of premixing, if any, would occur in this region within cone 51. In
order to arrive at the counter-rotating vortices required to exist within the
premix chamber according to claims 1 and 16, the Examiner relies on the

3 The Examiner does not place any reliance on the embodiment of Borissov
depicted in Figure 12 in support of the Examiner’s grounds for rejecting the
claims on appeal. Accordingly, neither will we. See 37 C.F.R. § 41.50(a)(1)
(“The Board, in its decision, may affirm or reverse the decision of the
examiner in whole or in part on the grounds and on the claims specified by
the examiner.”) (emphasis added). Although the Board is authorized to reject
claims under 37 C.F.R. § 41.50(b), no inference should be drawn when the
Board elects not to do so. See MPEP § 1213.02.
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Application 15/091,906

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flow pattern that exists outside of the Examiner’s own delineation of the
extents of the premix chamber. See Ans. 18 (illustrating Borissov’s
circulation region incorporated into Taylor). Borissov indicates that
“counterflow CF” is of “hot flue gases directed back into the throat 57.”
Borissov para. 70. We understand this to mean that the counterflow in
Borissov is mainly or entirely comprised of the gaseous products of
combustion as opposed to the fuel and oxidant reactants. Appeal Br. 24.
Thus, even under the Examiner’s proposed interpretation of the premix
chamber in Borissov, the Examiner fails to demonstrate how the proposed
combination would yield the claimed subject matter. Reply Br. 2.
Moreover, it is not clear on the record before us what benefit, if any,
could be expected by extracting the elements of Borissov’s combustion
region and placing them upstream of the combustion regions in either Taylor
or Stack. See Ans. 18, 23; Appeal Br. 27–28. The Examiner does not explain
and it is not apparent why Borissov’s teachings relating to the manner in
which combustion occurs in Borissov’s burner would be relevant to the
particular regions in Taylor and Stack in which the Examiner proposed to
incorporate elements from Borissov.
CONCLUSION
For the foregoing reasons, the Examiner’s rejections are REVERSED.
Appeal 2019-005331
Application 15/091,906

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DECISION SUMMARY
Claims
Rejected
35 U.S.C. § Reference(s)/Basis Affirmed Reversed
1 103 Taylor, Borissov 1
1–3, 5, 6, 8,
10–13, 16,
19, 24, 25
103 Stack, Taylor,
Borissov
1–3, 5, 6, 8,
10–13, 16,
19, 24, 25
4 103 Stack, Taylor,
Borissov, Krauklis
4
7, 9 103 Stack, Taylor,
Borissov,
Leinemann
7, 9
14, 15, 20,
22, 23
103 Stack, Taylor,
Borissov,
Wojcieson
14, 15, 20,
22, 23
17, 20, 21 103 Stack, Taylor,
Borissov, Mauzey
17, 20, 21
18 103 Stack, Taylor,
Borissov, Mauzey,
Wojcieson
18
Overall
Outcome
1–25

REVERSED