Appeal No. 2001-1628 Page 3
Application No. 09/054,794
primary air jets wherein said swirler airflow is swirled and delivered to said
venturi; and
(c) a fuel nozzle positioned inside the upstream end of said primary swirler
adjacent to said venturi and along the longitudinal axis thereof, said fuel nozzle
further comprising a fuel passage therein through which fuel is sprayed into said
venturi at a designated spray angle; and an air passage therein through which
purge airflow is discharged into said venturi, substantially parallel to the
longitudinal axis of said venturi; wherein said purge airflow is sufficient to provide
a boundary layer of air along the inner surface of said venturi wall.
THE REJECTION
Claims 1 to 7 stand rejected under 35 U.S.C. § 103 as being unpatentable over
Koshoffer et al.1 (Koshoffer) in view of Shekleton et al.2 (Shekleton). The examiner's
basis for this rejection as set forth on pages 3-4 of the answer (Paper No. 16, mailed
October 31, 2000) is as follows:
Koshoffer teaches the invention substantially as disclosed and as claimed: a
combustor 10 having a fuel injector assembly 38 comprising an air nozzle having
venturi walls 92 and a plurality of primary air jets 78 interposed between the
swirler upstream and downstream ends, and a fuel injector 40. However,
Koshoffer does not teach an air purge passage, the exits of the air purge
passage and the fuel passage being coaxial, the purge air preventing the fuel
from contacting the venturi walls of the air injector. It was known in the art at the
time of the claimed invention that fuel/air injectors of the type claimed
experienced coking problems when the fuel would contact the high temperature
surface of the venturi wall (see for example Ekstedt 3, 899, 834, col 1, ll. 44-46,
brought here for example of "common knowledge" only; Ekstedt is incorporated
by reference in Koshoffer col. 1, l. 27, and it is not part of the rejection).
Shekleton teaches a gas-turbine fuel injector comprising an air purge passage
1 U.S. Patent No. 4,584,834 issued April 29, 1986.
2 U.S. Patent No. 5,321,950 issued June 21, 1994.
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