Ex Parte Dadd

Board of Patent Appeals and Interferences

Jun 15, 2009

10890775 (B.P.A.I. Jun. 15, 2009)

UNITED STATES PATENT AND TRADEMARK OFFICE
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BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
________________

Ex parte PAUL M. DADD
________________

Appeal 2009-001633
Application 10/890,775
Technology Center 2800
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Decided:1 June 15, 2009
________________

Before KENNETH W. HAIRSTON, JOHN A. JEFFERY, and
BRADLEY W. BAUMEISTER, Administrative Patent Judges.

BAUMEISTER, Administrative Patent Judge.

DECISION ON APPEAL

1 The two-month time period for filing an appeal or commencing a civil
action, as recited in 37 C.F.R. 1.304, begins to run from the decided date
shown on this page of the decision. The time period does not run from the
Mail Date (paper delivery) or Notification Date (electronic delivery).
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STATEMENT OF THE CASE
Appellant appeals under 35 U.S.C. § 134 (2002) from the Examiner’s
final rejection of claims 1-3, 6-11, 14, 15, 17-21, and 23-40. Claims 41-68
have been withdrawn from prosecution for being directed towards non-
elected inventions.2 We have jurisdiction under 35 U.S.C. § 6(b) (2002).
We affirm-in-part.

A. Appellant’s invention
Appellant invented devices for regulating the pressure pulses and flow
pulses that are emitted from the exhausts of internal combustion engines,
compressors, poppet valves, and the like to attenuate the noise generated by
these pulses (Abstract). The first claimed embodiment of the invention3
includes a pair of concentrically-spaced-apart hollow cylinders, or
“enclosures,” forming a pair of fluid-flow passageways. The interior of the
inner enclosure forms the first, axial passageway, and the annular space
between the inner and outer enclosures forms the second passageway. At
least one vane is disposed in this annular space, causing the second
passageway to be helical in form. The second passageway is therefore
longer than the first passageway. The outlet end of the outer enclosure
extends axially beyond that of the inner enclosure and includes a reflecting
member. The reflecting member causes a portion of the pressure pulses
passing through the second, helical passageway to be reflected as expansion
waves back through the helical passageway.

2 See page 2 of the Office Action mailed Sept. 28, 2006, making the
requirement for restriction final.
3 See generally Spec. ¶¶ [0021] – [0032]; figs. 1 and 2.
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The second claimed embodiment of the invention4 is a variation of the
first embodiment, the two embodiments being related as a combination and
subcombination, respectively. The second embodiment includes all of the
structures of the first embodiment and further includes additional enclosures
attached to the entry end and exit end of the first embodiment. More
specifically, a pair of truncated cone-shaped enclosures is connected to the
respective ends of the first embodiment’s outer enclosure, and an additional
pair of hollow cylindrical enclosures is connected to the truncated ends of
the cones. Each of the additional pair of cylindrical enclosures therefore has
a smaller diameter than that of the outer enclosure.
Claims 1-3, 6-11, 14, 15, 17-21 and 23-30 are linking claims, reading
on both the first-embodiment subcombination and the second-embodiment
combination. Claims 31-40 are directed to the second-embodiment
combination.

B. The claims
Independent claim 1 is illustrative. It reads as follows:
1. A device adapted to be connected to a source of
pressure pulses and flow pulses so as to receive and
regulate the pressure pulses and flow pulses, the device
having:
an entry end with an opening therein adapted to be
placed in fluid communication with one or more outlets
in the source from which the pressure pulses and flow
pulses are emitted, and

4 See generally Spec. ¶¶ [0033] – [0036]; figs. 3 and 4.
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an exit end with an opening therein in fluid
communication with the opening in the entry end of the
device and allowing for the discharge from the device of
the pressure pulses and flow pulses generated by the
source after the pressure pulses and flow pulses
generated by the source have passed through the device;
and
a reflecting member located in the device so as to
reflect at least a portion of each pressure pulse, whereby
the noise generated by the pressure pulses is attenuated.

C. The references and rejections

The Examiner relies on the following prior art references to show
unpatentability:
Venter US 4,683,978 Aug. 4, 1987
Takagawa5 JP 5-332121 A Dec. 14, 1993

Claims 1-3, 6-11, 14, 15, 17-21, and 23-40 stand rejected under 35
U.S.C. § 103(a) as obvious over Venter in view of Takagawa.
Rather than repeat the arguments of Appellant or the Examiner, we
refer to the Brief and the Answer for their respective details.6 In this
decision, we have considered only those arguments actually made by
Appellant. Arguments which Appellant could have made but did not make

5 We refer to the official English translation, entered into the record June 8,
2009.
6 We refer to (1) the Appeal Brief filed July 10, 2007; (2) the Examiner’s
Answer mailed Sept. 14, 2007; and (3) the Reply Brief filed Nov. 14, 2007,
throughout this opinion.
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in the Briefs have not been considered and are deemed to be waived. See 37
C.F.R. § 41.37(c)(1)(vii).

ISSUES
The Examiner asserts that all of the claims on appeal are rendered
obvious when the exhaust silencer of Venter is modified to further possess
an exhaust muffler reflecting member as taught by Takagawa (Ans. 3-5).
Appellant first asserts that for various reasons it would not have been
obvious to combine Venter and Takagawa in the manner alleged by the
Examiner (App. Br. 7-18). Appellant also asserts that even if the references
were combined, the combination would not meet all the limitations of all of
the claims (App. Br. 7). The issues before us, then, are:
I. Has Appellant shown that the Examiner erred in finding that the cited
prior art collectively teaches or suggests an exhaust muffler that is capable
of attenuating exhaust noise that is generated by pressure and flow pulses
received from an exhaust source wherein the muffler comprises, among
other elements, a reflecting member that reflects at least a portion of each
pressure pulse, as recited by claims 1-3 and 17?
II. Has Appellant shown that the Examiner erred in finding that the cited
prior art collectively teaches or suggests modifying Venter’s muffler such
that (1) the cross-sectional area of the at least one second passageway is
approximately three times the cross-sectional area of the first passageway, as
recited in claims 7 and 8; and (2) the at least second passageway is
approximately equal to the flow area of the first passageway, as recited in
claim 10?
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III. Has Appellant shown that the Examiner erred in finding that the cited
prior art collectively teaches or suggests modifying Venter’s muffler so as to
include a reflecting member that comprises an annulus having an outer
circumference and an inner circumference, the annulus being attached along
its outer circumference to the second enclosure at the exit end of the device,
whereby the inner circumference of the annulus comprises the opening in the
exit end of the device, as recited in claims 6 and 9?
IV. Has Appellant shown that the Examiner erred in finding that the cited
prior art collectively teaches or suggests constructing a muffler with an
annulus-shaped reflecting member such that the first passageway and the at
least one second passageway terminate and merge short of the reflecting
member annulus by a distance at least sufficiently great so as not to impede
flow from the at least one second passageway to the opening in the exit of
the device, as recited in claim 15?
V. Has Appellant shown that the Examiner erred in finding that it would
have been obvious to have positioned a reflecting member within a muffler
constructed according to the combined teachings of Venter and Takagawa in
a manner such that the muffler would particularly enable the reflected
pressure pulse expansion wave to enter the exhaust outlet while the flow
pulse is being emitted from the outlet, as recited in claim 18?

FINDINGS OF FACT
The record supports the following Findings of Fact (FF) by a
preponderance of the evidence:
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1. Venter states that an object of the invention is to provide an exhaust
silencer for an internal combustion engine that provides good dampening of
noise without excessive back pressure (Venter, col. 1, ll. 1-10; col. 4, ll. 3-7).
2. Venter’s muffler 10 includes a cylindrical shell 16 having an entry
end with an opening adjacent to inlet chamber 26 and having an exit end
with an opening adjacent to outlet chamber 30 (Venter, e.g., fig. 1).
3. The entry end of Venter’s muffler is adapted to be placed in fluid
communication with the exhaust of an internal combustion engine (Venter,
fig. 1; col. 1, ll. 1-10).
4. The exit end of Venter’s muffler is in fluid communication with the
opening in the entry end of the device (Venter, fig. 1; col. 1, ll. 1-10).
5. Venter’s muffler includes a central axial tube 19 that is concentrically
spaced within cylindrical shell 16 (Venter, e.g., fig. 1; col. 2, ll. 25-62).
6. The central axial tube of Venter’s muffler has (1) an open end forming
an upstream axial inlet 20.1; (2) a closed downstream end “blanked” or
blocked off by transverse barrier 20.2; (3) an axial flow passage 20; and (4)
a transverse outlet 24 provided by a cluster of openings arranged at the
downstream end of the axial passage (Venter, e.g., fig. 1; col. 2, ll. 25-62).
7. Venter’s muffler includes a helical baffle 21 that defines a helical
passage 22 around the axial passage 20, within the shell 16 (Venter, col. 2,
ll. 32-34).
8. None of facts 1-7 are disputed by Appellant.
9. Venter’s transverse barrier prevents the portion of the exhaust
entering the axial flow passage of the central axial tube from leaving directly
through the tube’s downstream end. Instead, the exhaust is diverted to the
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tube’s cluster of openings that constitute the transverse outlet (Venter, e.g.,
fig. 1; col. 1, ll. 20-23).
10. After passing through the transverse outlet, the portion of the exhaust
from Venter’s axial flow passage recombines with the portion of exhaust
traveling through the helical passage and proceeds to pass through the
adjacent outlet chamber and exit from the outlet opening (Venter, e.g., fig. 1;
col. 1, ll. 14-23).
11. The cross-sectional area of Venter’s central axial tube is less than the
cross-sectional area of the opening in the exit end of the cylindrical shell
(Venter, fig. 1).
12. Venter discloses the following preferred or typical dimensions,
ranges, and ratios:
(1) the diameter of the inlet and outlet openings may be 50 mm
(col. 3, ll. 43-44);
(2) the radial length of the baffle may be about 40 mm (col. 3,
ll. 44-45);
(3) the diameter of the central axial support tube can vary from
about 20 mm to about 40 mm, depending upon the size and
power of the engine to which the silencer to be applied (col.
3, ll. 45-48);
(4) the length of the cylindrical shell may vary from about 250
mm to about 500 mm (col. 3, ll. 48-50);
(5) the helical flow passage at its mean diameter may be two to
six times as long as the axial flow passage (col. 1, ll. 41-42);
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(6) the axial length of the inlet chamber may be at the most one
diameter of the cylindrical shell (col. 1, ll. 46-48);
(7) the axial length of the outlet chamber may lie in the range
of four-tenths of one diameter and two-thirds of one
diameter of the cylindrical shell (col. 1, l. 65 – col. 2, l. 2);
(8) the ratio of the cross-sectional area of the axial flow passage
to the area of the helical flow passage may lie in the range of
one-fifth and two-thirds (col. 1, ll. 51-54);
(9) the flow area of the transverse outlet out of the axial flow
passage into the helical flow passage may be at least half the
cross-sectional area of the helical flow passage, and at the
most may be equal to twice the cross-sectional area of the
helical flow passage (col. 1, ll. 59-64);
(10) the axial pitch of the helical baffle may be at least equal to
the radial height of the baffle between the axial flow passage
and the cylindrical shell, and at the most may be equal to
three times the radial height (col. 2, ll. 3-6);
(11) the cylindrical shell’s axial length may be between two to
five times its diameter (col. 2, ll. 7-9); and
(12) the cross-sectional flow area of the helical exhaust passage
defined by the baffle within the cylindrical shell is of the
same order as that of the inlet and outlet openings and is
preferably greater (col. 3, ll. 38-42).
13. Venter discloses that “[t]he radial length of the baffle 21 may be about
40 mm, and the diameter of the central axial support tube 19 can vary from
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about 20 mm to about 40 mm, depending upon the size and power of the
engine to which the silencer is to be applied” (Venter, col. 3, ll. 44-48).
14. Venter indicates that the presence of the helical vanes is responsible
for dampening the noise (Venter, col. 3, ll. 30-37).
15. Venter states that “various combinations of shell, casing, core, and
baffle shape . . . are possible” (Venter, col. 3, ll. 51-54) and that “[f]or larger
engines or for high performance engines, the diameter of the cylindrical
shell of the silencer or its length may be increased, or both may be
increased” (Venter, col. 4, ll. 11-13).
16. Appellant’s Specification discloses that effective tuning of the engine
can be accomplished by selecting an appropriate cross-section-area ratio for
the passageways in combination with also properly spacing the reflecting
member from the outlets in the engine (Spec. ¶ [0029]).
17. Takagawa discloses that the configuration of third expansion chamber
34 causes exhaust gas “E” exiting the annular, second expansion chamber 33
to be reflected backwards by rear plate 22 towards the “blind patch” 27. The
blind patch 27 then re-reverses the gas flow towards the tail pipe 25
(Takagawa, Fig. 1, ¶ [0013]).
18. Appellant’s Specification discloses additional enclosures attached to
the annular reflecting member of Appellant’s subcombination without being
deemed to be part of the reflecting member (Spec. ¶¶ [0033] – [0045], figs.
3-8).
19. Venter teaches that it was known to outlet exhaust from a cylindrical
muffler through a frustro-conical-shaped outlet chamber 30 that is positioned
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downstream from an axial flow passage and helical passage (Venter, fig. 1;
col. 2, ll. 49-53).
20. Takagawa teaches that it was known to outlet exhaust from a
cylindrical muffler through a third expansion chamber 34 that is defined by a
flat, annular rear plate 22 and cylindrical tail pipe 25 (Takagawa, Fig. 1; ¶
[0013]).
21. Appellant’s Specification does not provide any express definition or
objective standard for determining how much a flow must be reduced in
order for the flow to be deemed to be “impeded.”
22. A general dictionary definition of “impede” is “to block or make
progress or action difficult” (The Free Dictionary,
http://www.thefreedictionary.com/impede (last visited May 11, 2009)).
23. Appellant’s Specification indicates that (1) the muffler may be
constructed such that a portion of each pressure pulse that is reflected by the
reflecting member will be reflected as an expansion wave back through the
opening in the entry end of the device to the one or more outlets in the
source such that the expansion wave arrives at the one or more outlets at the
same time that at least a portion of a flow pulse is being emitted from the
one or more outlets; and (2) this condition can be met by intentionally
spacing the reflecting member from the outlets a particular distance that “can
be determined empirically or through calculations applying formulas that
govern the speed of travel of the pressure pulses and the corresponding
reflected expansion waves” (Spec. ¶ [0026]).
24. Venter generally discloses a muffler that balances the goals of
silencing exhaust and reducing back pressure (Venter, col. 1, ll. 1-10).
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PRINCIPLES OF LAW
1. Appellant has the burden on appeal to the Board to demonstrate error
in the Examiner’s position. See In re Kahn, 441 F.3d 977, 985-86 (Fed. Cir.
2006).
2. In KSR Int’l Co. v. Teleflex Inc., 550 U.S. 398 (2007), the Supreme
Court emphasized “the need for caution in granting a patent based on the
combination of elements found in the prior art,” id. at 415, and discussed
circumstances in which a patent might be determined to be obvious. In
particular, the Court emphasized that “the principles laid down in Graham
[v. John Deere Co., 383 U.S. 1 (1966)] reaffirmed the ‘functional approach’
of Hotchkiss [v. Greenwood, 52 U.S. 248 (1850)],” id., and reaffirmed
principles based on its precedent that “[t]he combination of familiar
elements according to known methods is likely to be obvious when it does
no more than yield predictable results.” Id. at 416. The Court explained:
When a work is available in one field of endeavor, design
incentives and other market forces can prompt variations of it,
either in the same field or a different one. If a person of
ordinary skill can implement a predictable variation, § 103
likely bars its patentability. For the same reason, if a technique
has been used to improve one device, and a person of ordinary
skill in the art would recognize that it would improve similar
devices in the same way, using the technique is obvious unless
its actual application is beyond his or her skill.
Id. at 417. The operative question in this “functional approach” is thus
“whether the improvement is more than the predictable use of prior art
elements according to their established functions.” Id. The KSR Court also
cited United States v. Adams, 383 U.S. 39 (1966) (“when a patent claims a
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structure already known in the prior art that is altered by the mere
substitution of one element for another known in the field, the combination
must do more than yield a predictable result”) Id. at 416.

ANALYSIS
I.
Venter discloses a muffler that silences the exhaust of an internal
combustion engine (FF 1). Venter’s muffler 10 includes a cylindrical shell
16 having an entry end with an opening adjacent to inlet chamber 26 and
having an exit end with an opening adjacent to outlet chamber 30 (FF 2).
The entry end of Venter’s muffler is adapted to be placed in fluid
communication with the exhaust of an internal combustion engine (FF 3):
i.e., “in fluid communication with one or more outlets in a source from
which pressure pulses and flow pulses are emitted,” as recited in claim 1.
The exit end of Venter’s muffler is in fluid communication with the opening
in the entry end of the device (FF 4): i.e., the exit end’s opening “allow[s]
for the discharge from the device of pressure pulses and flow pulses
generated by the [exhaust] source after the pulses generated by the source
have passed through the device,” as required by claim 1. A central axial
tube 19 is concentrically spaced within cylindrical shell 16 (FF 5). The
central axial tube has (1) an open end forming an upstream axial inlet 20.1;
(2) a closed downstream end blocked off by transverse barrier 20.2; (3) an
axial flow passage 20; and (4) a transverse outlet 24 provided by a cluster of
openings arranged at the downstream end of the axial passage (FF 6). A
helical baffle 21 defines a helical passage 22 around the axial passage 20,
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within the shell 16 (FF 7). None of these facts are disputed by Appellant
(FF 8).
The Examiner asserts that Venter discloses all of the elements of
claim 1 except for “a reflecting member located in the device so as to reflect
at least a portion of each pressure pulse, whereby the noise generated by the
pressure pulses is attenuated” (Ans. 3-4). The Examiner then concludes that
it would have been obvious to modify Venter’s muffler so as to include the
reflecting member of Takagawa’s muffler (Ans. 4-5). Appellant disputes
that it would have been obvious to modify Venter’s muffler in such a
manner (App. Br. 7-13). With respect to claims 1-3 and 17, we need not
decide whether the Examiner’s proposed modification to Venter’s muffler is
proper because Venter itself discloses “a reflecting member” as required by
claim 1. Venter also discloses every other element of claim 1-3 and 17 as
well.
Venter’s transverse barrier prevents the portion of the exhaust
entering the axial flow passage of the central axial tube from leaving directly
through the tube’s downstream end. Instead, the exhaust is diverted—or
“reflected”—to the tube’s cluster of openings that constitute the transverse
outlet (FF 9). After passing through the transverse outlet, this portion of the
exhaust recombines with the portion of exhaust traveling through the helical
passage and proceeds to pass through the adjacent outlet chamber and exit
from the outlet opening (FF 10). Appellant even acknowledges that
the transverse barrier 20.2 at the distal end of the central axial
tube 19 causes whatever enters and passes along tube 19 to be
blocked and forced through perforated outlet 24 into helical
exhaust passage 22 where it will join and collide with whatever
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is passing along the exhaust passage 22. As a result, a
constriction and back pressure will be created in this area
(Reply Br. 3-4). Moreover, as the transverse barrier is disposed within and
normal to the exhaust flow path, one skilled in the art would understand that
the transverse barrier will reflect at least a portion of a pressure pulse
produced by the combustion engine. In re Preda, 401 F.2d 825, 826 (CCPA
1968) (“[I]n considering the disclosure of a reference, it is proper to take
into account not only specific teachings of the reference but also the
inferences which one skilled in the art would reasonably be expected to draw
therefrom”). As the transverse barrier blocks the flow and produces a back
pressure, the transverse barrier itself may be reasonably interpreted as
constituting “a reflecting member” as recited in claim 1.
Regarding dependent claims 2 and 3, the claimed means defining a
first cylindrical passageway reads on Venter’s central axial tube; the claimed
means defining at least one second, annular passageway reads on Venter’s
cylindrical shell that is arranged around the central axial tube so as to create
an annular space; and the claimed means located in the annular space for
establishing a second passageway in the form of a helical passageway reads
on Venter’s helical baffle 21. Moreover, as Venter’s first passageway length
through the central axial tube is shorter than the length of the second, helical
passageway, the first portion of each pressure pulse and flow pulse that
enters the first passageway will arrive at the opening in the exit end of
Venter’s device respectively before any fraction of the second portion of the
same pressure pulse or flow pulse that enters the second passageway arrives
at the opening in the exit end of the devices.
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Claim 17 depends from claim 2 and further recites, “wherein the
cross-sectional area of the first passageway is equal to or less than the cross-
sectional area of the opening in the exit end of the device.” The cross-
sectional area of Venter’s central axial tube is less than the cross-sectional
area of the opening in the exit end of cylindrical shell (FF 11).
In summary, Venter discloses all of the elements of claims 1-3 and 17.
As such, Appellant has not persuaded us that the Examiner erred in finding
that the cited prior art collectively teaches or suggests all of the elements of
these claims. See In re Meyer, 599 F.2d 1026, 1031 (CCPA 1979) (noting
that obviousness rejections can be based on references that happen to
anticipate the claimed subject matter). Accordingly, we affirm the
Examiner’s rejection of claims 1-3 and 17.

II.
Claims 7 and 8, which respectively depend from claims 2 and 3, both
further recite, “wherein the total cross-sectional area of the at least one
second passageway is approximately three times the cross-sectional area of
the first passageway” (emphasis added). Relying on Venter’s disclosure at
column 1, lines 59-64, the Examiner states that the ratio for the claimed
cross-sectional areas within Venter’s devices is approximately equal (Ans.
6). Appellant argues that Venter’s disclosure is ambiguous and
indiscriminate in its use of the terms “cross-sectional area” and “flow area”
(App. Br. 14). In support of this argument, Appellant compares the passage
of Venter cited by the Examiner with a second passage of Venter: “[t]he
ratio of the cross-sectional area of the axial flow passage to the area of the
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helical flow passage may lie in the range one-fifth and two-thirds” (App. Br.
14 (citing Venter, col. 1, ll. 52-55)).
Contrary to Appellant’s assertion, Venter’s discussion of the various
dimensions, areas, and ratios is more than reasonably clear; its usage of
terms is reasonably definite. Further, a close reading of Venter indicates that
the Examiner and Appellant have both misinterpreted Venter’s disclosure.
The ratio relied upon by the Examiner is a comparison of the area of the
cluster of openings through the wall of the central axial tube to the cross-
sectional area of the helical second flow passage (FF 12(9) (emphasis
added)). In contrast, the alternative ratio that was noted by Appellant is a
comparison of “the cross-sectional area of the axial flow passage to the area
of the helical flow passage (FF 12(8) (emphasis added)). But as Appellant
notes, the terms “cross-sectional area” and “area of the helical flow passage”
do not have the same meaning (App. Br. 14 (citing Appellant’s Spec. ¶
[0029], ll. 15-31)).7 The “cross-sectional area” is measured in a plane that is
perpendicular to the muffler’s axial direction (see, e.g., figs. 1 and 3; Venter
fig. 2). In contrast, “flow area” appears to reference an area within the
annular space that is bounded radially by the first and second enclosures (or
inner and outer cylindrical shells) and bounded axially by adjacent vanes
(Spec. ¶ [0029]).
A close reading of Venter therefore indicates that the cross-sectional
areas of relevance to claims 7 and 8 are actually disclosed on the second—
not first—page of Venter’s two-page Specification. More specifically,

7 Compare also claims 7 and 8 (reciting “total cross-sectional area”
(emphasis added)) with claims 10 and 11 (reciting “total flow area”
(emphasis added)).
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Venter discloses “[t]he radial length of the baffle 21 may be about 40 mm,
and the diameter of the central axial support tube 19 can vary from about 20
mm to about 40 mm, depending upon the size and power of the engine to
which the silencer is to be applied” (FF 13). Converting these dimensions
into areas,8 Venter discloses that the cross-sectional area of the second
passageway may be approximately 8 to 24 times the cross-sectional area of
the first passageway.
As Venter effectively discloses that the cross-sectional area ratio is in
the range of 8:1 to 24:1, Venter does not disclose a cross-sectional area ratio
of 3:1 as recited in claims 7 and 8. We must therefore decide whether it
would have been obvious to modify the relative areas of Venter’s axial tube
and cylindrical shell so as to satisfy this condition—that is, whether it would
have been obvious to increase the axial tube’s relative diameter so as to be
approximately one half the shell’s diameter.
Venter states that an object of the invention is to provide an exhaust
silencer for an internal combustion engine that provides good dampening of
noise without excessive back pressure (FF 1). Venter indicates that the
presence of the helical vanes is responsible for dampening the noise (FF 14).
Venter discloses the following preferred or typical dimensions or ranges: (1)
the diameter of the inlet and outlet openings; (2) the radial length of the
baffle; (3) the diameter of the central axial support tube; (4) the length of the
cylindrical shell; (5) the ratio of the helical flow passage to the axial flow

8 Aaxial = п(D/2)2; Ahelical = п[(RL + D /2)2 - Aaxial]; where Aaxial is the cross-
sectional area of the axial flow passage, Ahelical is the cross-sectional area of
the helical flow passage, D is the diameter of the axial flow passage, and RL
is the radial length of the helical flow passage.
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passage; (6) the respective ratios of the axial lengths of the inlet and outlet
chambers to the diameter of the cylindrical shell; (7) the ratio of the cross-
sectional area of the axial flow passage to the area of the helical flow
passage; (8) the ratio of the flow area of the transverse outlet out of the axial
flow passage into the helical flow passage to the cross-sectional area of the
helical flow passage; (9) the ratio of the axial pitch of the helical baffle to
the radial height of the baffle; (10) the ratio of the cylindrical shell’s axial
length to its diameter; and (11) the ratio of the cross-sectional flow area of
the helical exhaust passage to the inlet and outlet openings (FF 12). Venter
also states that “various combinations of shell, casing, core, and baffle shape
. . . are possible” and that “[f]or larger engines or for high performance
engines, the diameter of the cylindrical shell of the silencer or its length may
be increased, or both may be increased” (FF 15).
Read as a whole, one of ordinary skill in the art would reasonably
understand that the helical vanes of Venter’s annular passageway are more
efficient than the axial flow passage in dampening noise, while the presence
of the axial flow passage reduces the muffler’s back pressure. See Preda,
401 F.2d at 826 (noting that “in considering the disclosure of a reference, it
is proper to take into account not only specific teachings of the reference but
also the inferences which one skilled in the art would reasonably be
expected to draw therefrom”). As such, one would have further reasonably
expected that increasing the relative diameter of Venter’s axial tube so as to
be approximately one half of the shell’s diameter would increase the
muffler’s drop in back pressure while reducing the muffler’s noise
dampening capability.
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Appellant argues that the claimed ratio does not constitute an obvious
change in size or optimization (App. Br. 14-15). Rather, “the significance of
the specific relationship claimed is not taught by Venter . . . . The limitation
highlights a structural relationship that results in effective engine tuning, a
condition that is not disclosed by either Venter or Takagawa” (id.). This
argument is not convincing.
Appellant’s Specification discloses that effective tuning of the engine
can be accomplished by selecting an appropriate cross-section-area ratio for
the passageways in combination with also properly spacing the reflecting
member from the outlets in the engine (FF 16). But claims 7 and 8 do not
include any limitations regarding the reflecting member’s spacing. As such,
Appellant has not shown that any unexpected results are attributable solely
to the claimed ratio. See In re Peterson, 315 F.3d 1325, 1330 (Fed. Cir.
2003) (noting that
[i]n general, an applicant may overcome a prima facie case of
obviousness by establishing ‘that the [claimed] range is critical,
generally by showing that the claimed range achieves
unexpected results relative to the prior art range.’ That same
standard applies when, as here, the applicant seeks to optimize
certain variables by selecting narrow ranges from broader
ranges disclosed in the prior art. Moreover, the applicant's
showing of unexpected results must be commensurate in scope
with the claimed range.”
(second emphasis added) (citations omitted)).
Accordingly, Appellant has not persuaded us that the Examiner erred
in finding claims 7 and 8 to be obvious in view of the combined teachings of
the cited prior art. Accordingly, we affirm the obviousness rejection of
claims 7 and 8.
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Dependent claim 10 further recites, “[t]he device of claim 8 wherein
the total flow area of the at least one second passageway is approximately
equal to the flow area of the first passageway.” Based upon the same
rationale just applied to the claimed cross-sectional area ratio, we find that it
would have been further obvious to have also particularly set the flow areas
of the first and second passageways to be approximately equal. Changes to
the respective flow areas will dictate what percentage of exhaust passes
through the first and second passages. The specific percentages of exhaust
that pass through the respective passages will, in turn, also affect the
muffler’s noise dampening and back pressure.

III.
Claims 6 and 9, which respectively depend from claims 3 and 8, both
further recite:
wherein the reflecting member comprises an annulus having an
outer circumference and an inner circumference, the annulus
being attached along its outer circumference to the second
enclosure at the exit end of the device, whereby the inner
circumference of the annulus comprises the opening in the exit
end of the device.
Venter’s transverse barrier is not an annulus, and Venter does not
appear to disclose such an annulus. We must therefore decide whether
Venter’s muffler can be modified according to the teachings of Takagawa so
as to include an annulus-shaped reflecting member as recited in claims 6 and
9. Since the following analysis indicates that Venter’s muffler can be so
modified, we then decide whether such a modification would have been
obvious to one of ordinary skill in the art at the time of the invention.
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The Examiner’s rejection could have more clearly explained how
Venter’s muffler is being modified so as to further include Takagawa’s rear
plate 22 and tail pipe 35. Nonetheless, we understand the Examiner’s
proposed modification to entail removing Venter’s inlet truncated-cone
outlet chamber 30 and substituting in its place the combination of
Takagawa’s rear plate 22 and tail pipe 25. To wit, Venter’s combination of
the central axial tube with its transverse outlet, transverse barrier, cylindrical
shell, and helical baffle remains unchanged. The cylindrical shell remains
positioned relative to the central axial tube such that the shell’s outlet end
extends axially beyond the transverse barrier, thereby providing an outlet
expansion chamber (see Takagawa, Figs. 1, 3). Takagawa’s rear plate 22
and tail pipe 25 are attached to the outlet end of Venter’s shell such that a
space is maintained between the transverse barrier and the tail pipe.
According to such a modification, pulses exiting Venter’s helical
passage would be reflected from the rear plate into the outlet expansion
chamber, subsequently reflected a second time by the backside of the
transverse barrier, and ultimately passed through the tail pipe. See, e.g., FF
17 (Takagawa discloses that the configuration of expansion chamber 34
causes exhaust gas “E” exiting the annular, second expansion chamber 33 to
be reflected backwards by rear plate 22 towards the blind patch 27 (or
backside of the barrier for inner pipe 26). The blind patch 27 then re-
reverses the flow towards the tail pipe 25).
Restated, Takagawa’s substituted rear plate—not Venter’s transverse
barrier—would constitute the claimed annulus-shaped reflecting member. In
further regard to claim 9, the inner circumference of the rear plate annulus
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comprises the claimed opening in the exit end of the muffler. The tail pipe
25 is interpreted as constituting a separate structural element, additional to
the subcombination device of claim 9. See, e.g., Spec. ¶¶ [0033]-[0045];
Figs. 3-8; FF 18 (disclosing additional enclosures attached to the annular
reflecting member of Appellant’s subcombination without being deemed to
be part of the reflecting member, and thereby evidencing that Takagawa’s
tail pipe may be reasonably interpreted as not constituting part of the
reflecting member).
In short, claims 6 and 9 read on a muffler that is modified in the
manner set forth above. The only remaining issue is whether such a
modification would have been obvious.
In the present case, Venter teaches that it was known to outlet exhaust
from a cylindrical muffler through a frustro-conical-shaped outlet chamber
30 that is positioned downstream from an axial flow passage and helical
passage (FF 19). Takagawa teaches that it was known to outlet exhaust from
a cylindrical muffler through an outlet, third expansion chamber 34 that is
defined by a flat, annular rear plate 22 and cylindrical tail pipe 25 (FF 20).
As such, the modification of Venter outlined above appears to be nothing
more than the substitution of art-recognized functionally equivalent
structures for sealing the outlet end of a muffler. Either one of these
structures will work in conjunction with the rest of Venter’s muffler to
produce the predictable result of silencing exhaust to at least some degree.
We need not further speculate as to which, if either, of the two structures
works better. Claim 6 does not set forth any limitation or requirement
relating to how effectively the muffler performs.
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Claim 9 depends from claim 8, which was addressed in section II
above. As noted at the beginning of this section, claim 9, like claim 6,
further requires that the reflecting member comprises an annulus. Claim 11
depends from claim 9. Like claim 10, which was addressed above in section
II, claim 11 further requires that the flow areas of the first and second
passages be approximately equal. For the reasons set forth above in relation
to claim 6, combined with the reasons set forth in section II relating to
claims 8 and 10, we therefore sustain the Examiner’s rejection of claims 9
and 11.

IV.
Claim 14 depends from claim 6, and claim 15 depends from claim 14.
Claims 14 and 15 together further require that “the first passageway and the
at least one second passageway terminate and merge short of the annulus by
a distance at least sufficiently great so as not to impede flow from the at least
one second passageway to the opening in the exit of the device.” Appellant
argues that “[t]here is no teaching in either Venter or Takagawa that would
lead one skilled in the art to locate the back plate in the claimed manner”
(App. Br. 16). We disagree.
The Specification does not provide any express definition or objective
standard for determining how much a flow must be reduced in order for the
flow to be deemed to be “impeded” (FF 21). However, a general dictionary
definition of “impede” is “to block or make progress or action difficult” (FF
22 (emphasis added)). As such, the broadest reasonable interpretation of the
claim language, “a distance at least sufficiently great so as not to impede
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flow,” is “any distance at least sufficiently great so as not to completely
block flow.” See In re Am. Acad. of Sci. Tech Ctr., 367 F.3d 1359, 1369
(Fed. Cir. 2004) (noting that, during examination, the claims must be
interpreted as broadly as their terms reasonably allow). If “impede” were to
alternatively require any narrower interpretation, a question would be raised
as to whether the scope of claim 15 is sufficiently clear so as to inform the
public of the boundaries of what structures would infringe the claim.
Turning to the rejection, it would have been obvious to one of
ordinary skill in the art to have constructed the muffler according to the
combined teachings of Venter and Takagawa [hereinafter the prior-art
muffler] such that this muffler would have a sufficiently great space between
the second passageway and the combination of the rear plate reflecting
member and tail pipe so as to not completely block the flow. This is so
because one of ordinary skill would have desired the prior-art muffler to
work as intended—to discharge exhaust. When so spaced, the annular rear
plate reflecting member would not “impede” flow.

V.
Dependent claim 18 recites:
18. The device of claim 1 wherein the reflecting member is
adapted to be spaced from at least one of the one or more
outlets a distance such that the at least a portion of each
pressure pulse that is reflected by the reflecting member is
reflected as an expansion wave back through the opening in the
entry end of the device to the one or more outlets in the source
such that the expansion wave arrives at the one or more outlets
while at least a portion of a flow pulse is being emitted from the
one or more outlets.
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(emphasis added). The Examiner acknowledges that Venter does not
disclose this limitation (Ans. 3-4), but states that Takagawa does (Ans. 4).
More specifically, the Examiner contends that this limitation merely
constitutes an intended use of the claimed structure and that the language
does not structurally distinguish the claimed invention over the prior-art
muffler (Ans. 12).
The Examiner is correct that the functional language following the
claim language “adapted to be” is directed towards an intended use of the
device. The referenced engine outlets are never positively recited in claim
18 or parent claim 1. Also, neither of claims 1 and 18 requires the further
presence of any inlet-end enclosures that may interconnect the claimed
muffler to the referenced exhaust outlet. As such, the Examiner is correct
that the prior-art muffler must merely possess a structure that is capable of
being connected to an exhaust outlet—either directly or indirectly by means
of at least one or more enclosures that form an inlet end—so as satisfy the
claimed criteria. See Ex parte Masham, 2 USPQ2d 1647 (BPAI 1987)
(noting that a claim containing a “recitation with respect to the manner in
which a claimed apparatus is intended to be employed does not differentiate
the claimed apparatus from a prior art apparatus” if the prior art apparatus
teaches all the structural limitations of the claim).
Nonetheless, the Examiner still has the burden of demonstrating that
the prior-art muffler would in fact possess all of the structural limitations
that would make it capable of producing the criteria recited in claim 18.
However, the Examiner does not cite to any evidence that indicates—either
expressly, implicitly, or inherently—that the prior-art muffler would be
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capable of producing the criteria required by claim 18. The Examiner’s
Answer is simply devoid of any rationale or basis to support the bald
conclusion that the prior-art muffler would be capable of causing at least a
portion of each pressure pulse that is reflected by the reflecting member to
be reflected as an expansion wave back through the opening in the entry end
of the device to the one or more outlets in the source such that the expansion
wave arrives at the one or more outlets at the same time that at least a
portion of a flow pulse is being emitted from the one or more outlets.
Further, the record alternatively indicates that these claimed events
will not inherently occur at the same time for all prior-art mufflers,
irrespective of the reflector plate’s position. Rather, Appellant’s
Specification indicates that this condition is met by intentionally spacing the
reflecting member from the outlets a particular distance that “can be
determined empirically or through calculations applying formulas that
govern the speed of travel of the pressure pulses and the corresponding
reflected expansion waves” (FF 23). This disclosure seems to further imply
that it is at least theoretically possible for the reflecting plate to be positioned
either too close to, or too far from, the exhaust outlet for the flow pulse and
reflected pressure pulse to pass through the exhaust outlet simultaneously.
For example, it might be the case that the speed at which pressure
pulses propagate is so much faster than the speed at which flow pulses
propagate that it would always be possible to satisfy the criteria of claim 18
with all prior-art mufflers, irrespective of the reflector plate’s position within
the muffler. To wit, the criteria of claim 18 could always be satisfied by
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providing exhaust source outlets, inlet-end connectors, or both of sufficient
and appropriate length.
Alternatively though, it might be the case that the speed at which
pressure pulses propagate is so close to the speed at which flow pulses
propagate that it would be possible to construct a prior-art muffler that is not
capable of satisfying the criteria of claim 18. To wit, the rate at which the
pressure pulse propagates may be so close to that of the flow pulse that,
depending on the prior-art muffler’s dimensions and the reflecting plate’s
position therein, the pressure pulse expansion wave might not be able to
reach the exhaust outlet by the time the pressure pulse exits the exhaust
outlet.
There simply is not sufficient evidence on the record, however, to
determine which of these scenarios is correct. Moreover, the Examiner
apparently concedes that a prior-art muffler’s ability to satisfy the condition
required by claim 18 does depend upon the reflector plate’s position within
the muffler. The Examiner concedes this point by further contending that
the claim language regarding the reflector member’s spacing constitutes (1)
an obvious discovery of the optimum or working range pursuant to In re
Aller;9 and (2) an obvious change in size pursuant to In re Rose10 (Ans. 12).
Accordingly, the Examiner has not established a prima facie case that prior-
art mufflers according to the combined teachings of Venter and Takagawa
would necessarily be capable of satisfying the condition required by claim
18.

9 In re Aller, 220 F.2d 454, 456 (CCPA 1955).
10 In re Rose, 220 F.2d 459 (CCPA 1955).
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The Examiner has also failed to establish a prima facie case that it
would have been obvious to have positioned the reflector member within the
prior-art muffler in a manner that would particularly enable the reflected
pressure pulse expansion wave to enter the exhaust outlet while the flow
pulse is being emitted from the outlet. Venter generally discloses a muffler
that balances the goals of silencing exhaust and reducing back pressure (FF
24), but neither Venter nor Takagawa appears to teach or suggest that these
goals may be balanced by specifically causing the conditions recited in claim
18 to occur simultaneously. Further, the Examiner provides no evidence on
appeal that such an approach was known at the time of the invention.
“‘[R]ejections on obviousness grounds cannot be sustained by mere
conclusory statements; instead, there must be some articulated reasoning
with some rational underpinning to support the legal conclusion of
obviousness.’” KSR, 550 U.S. at 418 (quoting Kahn, 441 F.3d at 988). The
Examiner’s invocation of the holdings in Aller and Rose is insufficient.
Citations to case law do not constitute, nor substitute for, evidence on the
record.
For the foregoing reasons, Appellant has persuaded us of error in the
Examiner’s obviousness rejection of claim 18. Accordingly, we reverse the
Examiner’s rejection of that claim and also claims 19-21 and 23-40 which
depend from claim 18.

CONCLUSIONS OF LAW
I. Appellant has not shown that the Examiner erred in finding that the
cited prior art collectively teaches or suggests an exhaust muffler that is
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capable of attenuating exhaust noise that is generated by pressure and flow
pulses received from an exhaust source wherein the muffler comprises,
among other elements, a reflecting member that reflects at least a portion of
each pressure pulse. Accordingly, Appellant has not shown that the
Examiner erred in rejecting claims 1-3 and 17 under § 103.
II. Appellant has not shown that the Examiner erred in finding that the
cited prior art collectively teaches or suggests modifying Venter’s muffler
such that (1) the cross-sectional area of the at least one second passageway is
approximately three times the cross-sectional area of the first passageway;
and (2) that the at least second passageway is approximately equal to the
flow area of the first passageway. Accordingly, Appellant has not shown
that the Examiner erred in rejecting claims 7, 8, and 10 under § 103.
III. Appellant has not shown that the Examiner erred in finding that the
cited prior art collectively teaches or suggests modifying Venter’s muffler so
as to include a reflecting member that comprises an annulus having an outer
circumference and an inner circumference, the annulus being attached along
its outer circumference to the second enclosure at the exit end of the device,
whereby the inner circumference of the annulus comprises the opening in the
exit end of the device. Accordingly, Appellant has not shown that the
Examiner erred in rejecting claims 6, 9, and 11 under § 103.
IV. Appellant has not shown that the Examiner erred in finding that the
cited prior art collectively teaches or suggests constructing a muffler with an
annulus-shaped reflecting member such that the first passageway and the at
least one second passageway terminate and merge short of the reflecting
member annulus by a distance at least sufficiently great so as not to impede
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flow from the at least one second passageway to the opening in the exit of
the device. Accordingly, Appellant has not shown that the Examiner erred
in rejecting claims 14 and 15 under § 103.
V. Appellant has shown that the Examiner erred in finding that it would
have been obvious to have positioned a reflecting member within a muffler
constructed according to the combined teachings of Venter and Takagawa in
a manner such that this muffler would particularly enable the reflected
pressure pulse expansion wave to enter the exhaust outlet while the flow
pulse is being emitted from the outlet. Accordingly, Appellant has shown
that the Examiner erred in rejecting claims 18-21 and 23-40 under § 103.

DECISION
We sustain the Examiner's rejection with respect to claims 1-3, 6-11,
14, 15, and 17. Therefore, the Examiner’s rejection of claims 1-3, 6-11, 14,
15, and 17 is affirmed.
We do not sustain the Examiner's rejections with respect to claims 18-
21 and 23-40. Therefore, the Examiner’s rejection of claims 18-21 and 23-
40 is reversed.
No time period for taking any subsequent action in connection with
this appeal may be extended under 37 C.F.R. § 1.136(a)(1)(iv).

AFFIRMED-IN-PART

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