Appeal No. 1999-1778
Application No. 08/888,365
increased stress to these areas of the wall” (column 2, line 67
through column 3, line 2). Concerning the configuration of the
fins, Booth states the following:
As shown in FIG. 2 and in these and other
preferred embodiments, the apex angle of fin 26 is
preferably asymmetrical with respect to a radius 32 of
the circular transverse cross-sectional shape. Such
radius 32 intersects a spirally disposed fin 26 to
form respective angles of approximately 13E and
approximately 15E with regard to sloped sides 28,30 of
the inverted V-shaped fin 26. In such a manner,
sloped sides 28,30 of the inverted V-shaped fin 26 do
not in these preferred embodiments slope down at the
same angle with respect to inner surface 16 of tubular
member 10. Accordingly, the shape of the several
spiral grooves 24 between the spirally disposed fins
26 is that of an irregular trapezoid, as shown in FIG.
2. [Column 4, lines 14-26; emphasis added.]
The essence of the examiner’s rejection of claim 1 is that,
although Fujimoto does not disclose the convex portion (6) and
inner fins (7) of the heat exchanger tube as being asymmetrical
in cross-sectional shape, it would have been obvious to one of
ordinary skill in the art to so shape these elements of
Fujimoto’s tube in view of the teachings of Booth.
However, appellants argue on page 5 of the brief that Booth
proposes to overcome the tendency of the tube to split by
increasing the amount of wall available to be stretched by
7
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