Ex Parte Dewey et al

Board of Patent Appeals and Interferences

Oct 20, 2009

10828420 (B.P.A.I. Oct. 20, 2009)

UNITED STATES PATENT AND TRADEMARK OFFICE
____________

BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
____________

Ex parte SCOTT DEWEY and JOHN WHEAT
____________

Appeal 2009-004481
Application 10/828,420
Technology Center 2800
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Decided: October 20, 2009
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Before EDWARD C. KIMLIN, CHARLES F. WARREN, and
TERRY J. OWENS, Administrative Patent Judges.

KIMLIN, Administrative Patent Judge.

DECISION ON APPEAL
This is an appeal from the final rejection of claims 1-19. We have
jurisdiction under 35 U.S.C. § 6(b).
Claim 1 is illustrative:

1. A fuel cell system comprising:

a high voltage component;
Appeal 2009-004481
Application 10/828,420

a fuel cell stack including a positive terminal and a negative
terminal;

a first conductor electrically coupled to the positive terminal
and the high voltage component;

a second conductor electrically coupled to the negative terminal
and the high voltage component, wherein a current propagating through the
first and second conductors is in opposite directions;

a magnetic field concentrator including an opening, said first
and second conductors extending through the opening, wherein a current
propagating through the first and second conductors generate magnetic fields
that are concentrated by the magnetic field concentrator; and

a magnetic sensor positioned relative to the magnetic field
concentrator, said sensor detecting the magnetic field in the magnetic field
concentrator and providing a difference signal representative of the
difference between the current propagating through the first conductor and
the current propagating through the second conductor.

The Examiner relies upon the following references as evidence of
obviousness (Ans. 2):
Burns 3,621,334 Nov. 16, 1971
Kurokami 7,079,406 B2 Jul. 18, 2006

Appellants’ claimed invention is directed to a fuel cell system
comprising, inter alia, a magnetic field concentrator (32) having an opening
through which first and second conductors extend. Current propagated
through the conductors generates magnetic fields that are concentrated by
the concentrator and sensed by a magnetic sensor (42). Current flows
through the conductors in opposite directions and, during normal stack
operation, the current in both conductors is the same, thereby generating a
zero differential which is detected by the sensor. When the system fails by
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Application 10/828,420

the high voltage component (68) becoming electrically coupled to the
ground, the current propagating through the conductors will be different, and
the difference between the magnetic fields generated by the conductors will
be detected by the sensor, which will in turn trigger a signal to shut the
system down.
Appealed claims 1-19 stand rejected under 35 U.S.C. § 103(a) as
being unpatentable over Burns in view of Kurokami.
Appellants do not present separate arguments for any particular claim
on appeal. Accordingly, all the appealed claims stand or fall together with
claim 1.
We have thoroughly reviewed each of Appellants’ arguments for
patentability. However, we are in complete agreement with the Examiner
that the claimed subject matter would have been obvious to one of ordinary
skill in the art within the meaning of § 103 in view of the applied prior art.
Accordingly, we will sustain the Examiner’s rejection for essentially those
reasons expressed in the Answer, and we add the following primarily for
emphasis.
Appellants do not dispute the Examiner’s factual determination that
Burns, like Appellants, discloses a ground fault sensing apparatus
comprising a magnetic field concentrator having an opening through which
first and second conductors extend. Appellants acknowledge that the
magnetic core 30 of Burns operates in the same manner as the claimed
magnetic field concentrator, i.e., as a sensor which detects a differential in
the magnetic fields generated by the two conductors when a ground fault
occurs such that the system can be shut down. As acknowledged by the
Examiner, Burns does not specify that the ground fault sensing apparatus is
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Application 10/828,420

part of a fuel cell system. However, Kurokami teaches that it was known in
the art to use a ground fault detector with a variety of power sources,
including a fuel cell. Consequently, we find no error in the Examiner’s legal
conclusion that it would have been obvious for one of ordinary skill in the
art to employ the particular ground fault sensing apparatus of Burns in a fuel
cell system. In our view, Appellants’ acknowledgement in the present
Specification that fault isolation detection systems were known to be used in
fuel cell systems for safety purposes underscores the obviousness of using
the particular system of Burns. Appellants have advanced no reason why
one of ordinary skill in the art would have been dissuaded from using the
ground fault sensing circuit of Burns in a fuel cell system.
Appellants submit that “there is not enough detail in the discussion of
Kawakami [sic, Kurokami] to show that the current detector 12 employs
magnetic field cancellation, as claimed” (Reply Br. 1, second para.).
However, the particulars of a circuit using magnetic field cancellation are
disclosed by Burns.
Appellants also submit that load 70 of Burns and system 3 of
Kurokami are not described as high voltage loads. However, as pointed out
by the Examiner, the claim language “a high voltage component” is relative
in nature and, furthermore, Appellants concede that the use of high voltage
components was well-known in the art. Appellants have not made any
argument that one of ordinary skill in the art would not have considered the
ground fault sensing systems of Burns and Kurokami to be suitable for a
system that comprises a high voltage component.
As a final point, we note that Appellants base no argument upon
objective evidence of non-obviousness, such as unexpected results.
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Application 10/828,420

In conclusion, based on the foregoing and the reasons well stated by
the Examiner, the Examiner’s decision rejecting the appealed claims 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) (2008).

AFFIRMED

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