Appeal 2006-1849
Application 10/387,139
For two reasons, we are not convinced by Appellants’ argument that,
since Christians does not disclose any condenser icing problem, there is no
motivation to combine Hipsky’s two turbine environmental control system
that prevents icing with Christians’ integrated environmental control system.
First, Christians indicates that ice forms in the passages 140 and 142 leading
to the condenser 92 (col. 7, ll. 65-67, Figure 1). Ice formation in the
passages leading to the condenser suggests ice formation in the condenser.
Second, though Christians does use some of the heated bleed air to remove
the ice from the passages, using the two turbine system of Hipsky would
allow the air to be made colder using the second turbine while also
preventing ice formation in the condenser and in the passages leading
thereto. This benefit from using the two turbine system provides added
motivation for combining Hipsky’s second turbine with an air cycle machine
in Christians’ integrated environmental control system. Using Hipsky’s two
turbine environmental control system imparts greater temperature control of
the air leaving each of the turbines, such that the air leaving the first turbine
will be at a higher temperature thereby preventing ice formation (Hipsky,
col. 4, ll. 45-47).
We are not persuaded by Appellants’ argument that Hipsky’s
disclosure that icing is advantageous is some applications teaches away from
the combination. In fact, the ability to control whether or not icing occurs is
a desirable feature that is achievable using the two turbine system of Hipsky
where the expansion ratios of the turbines are controlled (Hipsky, col. 5, ll.
10-25). Instead of teaching away from the combination of Hipsky’s second
turbine with an air cycle machine in Christians’ integrated environmental
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