Appeal No. 2002-1840
Application 09/134,993
with the late stage rotor disks 3 and 6 of a high pressure
compressor. In proposing to combine Liebl, Burrus and Zaehring
to reject claim 1, the examiner submits that it would have been
obvious to one of ordinary skill in the art
to have the cooling air of Liebel [sic] further cooled
by the heat exchanger of Burrus, because the higher
pressure ratios in jet engines at the time of the
claimed invention rendered the air at the compressor
exit too hot for cooling purposes . . . [and] to use
the Zaehring compressor [sic, impeller] in the Liebel
[sic] gas turbine engine, in order to enable the
cooling flow 14 [to] negotiate the adverse pressure
gradient required to reach the root of the last
compressor stage of the engine [final rejection, page
3].
Liebl, however, gives no indication that recycled air stream
14 is too hot for its intended purpose or is impeded from
entering the compressor by an adverse pressure gradient. The
examiner’s speculation that the Liebl engine experiences these
problems is completely lacking in evidentiary support.
Furthermore, Burrus does not use heat exchanger 100 to prepare
air for cooling a compressor and Zaehring does not utilize
impeller ribs 9 to feed cooling air into a compressor. In this
light, it is evident that the only suggestion for combining
Liebl, Burrus and Zaehring in the manner proposed by the examiner
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