Ex Parte De Marcos et al

Patent Trial and Appeal Board

Nov 18, 2014

11503163 (P.T.A.B. Nov. 18, 2014)

UNITED STATES PATENT AND TRADEMARK OFFICE
____________________

BEFORE THE PATENT TRIAL AND APPEAL BOARD
____________________

Ex parte ELENA DE MARCOS, CHRISTIAN STEINBACH,
NICOLAS ULIBARRI, and
MARTIN ANDREA VON PLANTA
____________________

Appeal 2012-007045
Application 11/503,163
Technology Center 3700
____________________

Before: JENNIFER D. BAHR, MICHAEL L. HOELTER, and
BRANDON J. WARNER, Administrative Patent Judges.

BAHR, Administrative Patent Judge.

DECISION ON APPEAL

STATEMENT OF THE CASE
Elena De Marcos et al. (Appellants) appeal under 35 U.S.C. § 134
from the Examiner’s decision rejecting claims 1, 2, 4–6, 9, 10, 12, 13, and
16–21 under 35 U.S.C. § 103(a) as being unpatentable over Döbbeling ’574
(US 6,702,574 B1, issued Mar. 9, 2004), Bortz (US 5,470,224, issued Nov.
28, 1995), Döbbeling ’878 (US 5,586,878, issued Dec. 24, 1996), Gutmark
(US 6,918,256 B2, issued July 19, 2005), Eisinger (US 5,489,202, issued
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Application 11/503,163

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Feb. 6, 1996), and Feldermann (US 5,944,507, issued Aug. 31, 1999).1 We
have jurisdiction under 35 U.S.C. § 6(b).
We AFFIRM.

THE CLAIMED SUBJECT MATTER
Claim 1, reproduced below, is illustrative of the claimed subject
matter.
21. A premix burner for operating a combustion chamber with a
gaseous and/or liquid fuel, comprising:
a swirl generator for inducing a swirl flow in an
incoming combustion air flow; and
means for injecting fuel into the swirl flow, the swirl
generator having at least two cone shell segments which fit
together to form a flow body and together enclose a conically
formed swirl space with a cone angle y and air inlet slits
directed tangentially to the length of the cone, wherein the cone
angle y is greater than or equal to 20°, the swirl generator has a
downstream burner diameter of greater than 180 mm, and the
burner length is less than one meter.

OPINION
Appellants argue all the rejected claims (i.e., claims 1, 2, 4–6, 9, 10,
12, 13, and 16–21) together in contesting the rejection. Appeal Br. 4–8.
Thus, we select claim 21 to decide the appeal as to all of the claims in the
group. 37 C.F.R. § 41.37(c)(1)(vii) (2011).

1 The Examiner’s statement of the rejection as being based upon only
Döbbeling ’574, Döbbeling ’878, and Bortz is puzzling, in light of the
Examiner’s reliance on the additional references in explaining the rejection.
See Final Rejection 3, 5, 6; Answer 4, 6, 8.
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Application 11/503,163

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The Examiner found that Döbbeling ’574 discloses a premix burner
comprising all of the structural elements recited in claim 21, but does not
specifically disclose a cone angle greater than or equal to 20°, a downstream
burner diameter of greater than 180 mm, and a burner length of less than one
meter, as also recited in the claim. Answer 4–7. However, the Examiner
found disclosure in the prior art of a premix burner cone half angle of 10.95°
(i.e., a cone angle of 21.9°) and a downstream premix burner diameter of 33
inches (i.e., 838 mm). Id. at 6, 7 (citing Döbbeling ’878 and Bortz,
respectively).2 The Examiner additionally found that Gutmark and Eisinger
show that “the general condition of the burner length is known in [the] prior
art” (id. at 10) and that swirl burner length was recognized as a result-
effective variable at the time of Appellants’ invention (id. at 8, 10,
discussing the prior art’s teaching of varying burner length for optimization).
In light of the teachings of Döbbeling ’878, Bortz, Gutmark, and
Eisinger, the Examiner reasoned that a cone angle of about 20°, a
downstream burner diameter of greater than 180 mm, and a burner length of
less than one meter are “deemed a matter of optimization within prior art
conditions.” Id. at 7 (citing In re Aller, 220 F.2d 454, 456 (CCPA 1955)).
Referring to their annotated reproduction of Figure 1 of Döbbeling
’574, Appellants argue that the change of direction and impingement of the
flow on the wall of transition geometry 200 of Döbbeling ’574 can destroy
the swirl generated in swirl generator 100, and that increasing the cone angle
(C) of the swirl generator would decrease the angle (B) defined by the cone

2 The Examiner also mentioned Feldermann’s teaching of a swirl burner
cone angle of between 30 and 40 degrees, but appears to have relied
primarily on Döbbeling ’878 for the cone angle. Id. at 8.
Appeal 2012-007045
Application 11/503,163

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of the swirl generator and the walls of the transition geometry, thereby
degrading burner operation. Appeal Br. 6. Therefore, according to
Appellants, it would “make no sense to increase angle C.” Id. Appellants
argue that “in Bortz, the downstream diameter can be almost freely chosen,
because there are no problems related to flow or swirl separation caused by
the cone angle and thus the downstream diameter”; that Bortz’s disclosure of
an outer burner diameter of 33 inches is completely unrelated to a swirl
generator such as that of Döbbeling ’574; and that the differences between
the burners of Döbbeling ’574 and Bortz are of such a nature that an
ordinarily skilled artisan, even having been made aware of Bortz’s
disclosure, would not have been prompted to modify Döbbeling ’574 to have
a burner diameter of greater than 180 mm. Id. at 5.
Appellants’ arguments are not convincing. Even accepting
Appellants’ position that there is some minimum value required for the angle
(B) defined between the cone of the swirl generator and the walls of the
transition geometry, in order to avoid degradation of operation, Appellants
do not direct our attention to any evidence that might suggest that a cone
angle of 20° or a downstream diameter of greater than 180 mm would create
an angle (B) falling below such minimum value. Appellants’
characterization of the Examiner’s combination as increasing the cone angle
of Döbbeling ’574 is pure speculation because, as noted by the Examiner,
Döbbeling ’574 “is silent as [to] the value of the cone angle.” Answer 9. As
for any differences between the burners of Döbbeling ’574 and Bortz, we
note that Bortz, read as a whole, characterizes the 33-inch burner diameter of
the two stage rapid mix burner as being more suitable for retrofit
applications than the larger diameter of the basic rapid mix burner (RMB).
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Application 11/503,163

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Bortz, col. 4, ll. 53–55 (pointing out that the larger size of the basic RMB
can create difficulties in retrofit applications); col. 11, ll. 5–11 (describing a
basic RMB exit diameter of 60 inches, as compared with the 33-inch
diameter of the improved two stage rapid mix burner). In other words, Bortz
does not characterize the 33-inch (i.e., 838-mm) burner diameter as being
larger than a conventional burner diameter, nor do Appellants direct us to
any evidence showing that the claimed downstream burner diameter is in
excess of that which would have been contemplated by a person of ordinary
skill in the art for the burner of Döbbeling ’574. Accordingly, Appellants do
not demonstrate error in the Examiner’s determination that a person of
ordinary skill in the art, faced with the silence of Döbbeling ’574 with
respect to cone angle and downstream burner diameter, would have looked
to conventional cone angle and downstream burner diameter values such as
those taught in Döbbeling ’878 and Bortz for the burner of Döbbeling ’574.
Finally, the Examiner correctly determined that the claimed burner
length amounts to routine optimization. Where the general conditions of a
claim are disclosed in the prior art, and the optimized variable is a result-
effective variable, it is not inventive to discover the optimum or workable
ranges by routine experimentation. In re Applied Materials, Inc., 692 F.3d
1289, 1295 (Fed. Cir. 2012); see In re Boesch, 617 F.2d 272, 276 (CCPA
1980) (“[D]iscovery of an optimum value of a result effective variable . . . is
ordinarily within the skill of the art.”) (citations omitted). Eisinger
evidences recognition in the prior art that burner length is a result-effective
variable, and, in fact, illustrates a process of optimizing burner length for a
typical steam generation system, to avoid the critical length that will result in
severe thermoaccoustic oscillations. Eisinger, col. 7, l. 58 to col. 9, l. 59.
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Application 11/503,163

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Appellants argue that Eisinger discloses a burner length of 1977 mm,
which exceeds one meter, and thus teaches away from a burner length of less
than one meter, as called for in claim 21. Appeal Br. 7. This argument
evinces a misapprehension of Eisinger’s teachings. Eisinger does not teach
a burner length of 1977 mm. Rather, Eisinger finds, for the particular
optimization example illustrated, that this length for the cold section of the
burner approximates the predicted critical length that results in severe
thermoaccoustic oscillations; thus, Eisinger teaches avoiding this length.
See Eisinger, col. 9, ll. 22–59. Specifically, Eisinger teaches, for the
illustrated optimization, a cold section length of greater than or equal to
3095 mm or less than or equal to 132 mm, and, thus, an overall length of
greater than or equal to 3745 mm or less than or equal to 782 mm,3 to
provide an appropriate safety margin. Id., col. 9, ll. 39–59.
Appellants additionally argue that Döbbeling ’878 teaches that the
burner length should be extended to get the droplets to evaporate. Appeal
Br. 7. According to Appellants, given the disclosure of Döbbeling ’878,
“the burner length must be long.” Id. at 8. This line of argument is not
convincing because it is directed to Döbbeling ’878, which is relied upon
only for its teaching with respect to cone angle, and not to Döbbeling ’574,
which is the primary reference the Examiner proposes to modify. Moreover,
the broad assertion that the burner length must be long is insufficient to
establish that a length of one meter, which falls within the claimed range,
would be too short for the burner of Döbbeling ’574.

3 Eisinger’s indication of a burner length less than or equal to “132 mm”
(col. 9, l. 59) is an ostensible error; this is the calculated value for the cold
section length.
Appeal 2012-007045
Application 11/503,163

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For the above reasons, Appellants’ arguments fail to apprise us of
error in the Examiner’s rejection of claim 21. We sustain the rejection of
claims 1, 2, 4–6, 9, 10, 12, 13, and 16–21 as unpatentable over
Döbbeling ’574, Bortz, Döbbeling ’878, Gutmark, Eisinger, and
Feldermann.

DECISION
The Examiner’s decision rejecting claims 1, 2, 4–6, 9, 10, 12, 13, and
16–21 as unpatentable over Döbbeling ’574, Bortz, Döbbeling ’878,
Gutmark, and Eisinger is affirmed.

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

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