Appeal No. 2006-2839
Application No. 10/699,229
not enclose the latter. It is further argued (id.) that since sleeve portion 24 is not a
seal, moisture accumulated on piston 14 may enter the gap between sleeve portion
24 and piston 14 and penetrate into a space between sleeve 22 and cylinder 12.
Appellants add (id.) that neither reference teaches an end portion of a heat-shrink
sleeve that extends axially inwards from the cylinder's end.
From our review we find, for the reasons which follow, that the combined
teachings of Freitag and Kaufmann would not have suggested to an artisan the
invention recited in claim 1. At the outset, we note that because Freitag's
pneumatic spring is designed for use in the automotive industry, specifically for
motor hoods, trunk lids and the rear gate of a station wagon (col. 3, lines 59-62),
we find that the pneumatic spring is for use in an environment exposed to moisture.
In addition, we do not agree with appellants' assertion (reply brief, page 2) that
sleeve portion 24 of Kaufmann is not a seal. We find from the disclosure of
Kaufmann (col. 2, lines 46-48) that "the shrink-wrap sleeve has a cylindrical
segment 24 that wraps around an axial portion of the piston rod 14, forming a seal
which effectively prevents moisture or other contaminants from penetrating along
the rod to the cylinder 12" [emphasis added].
However, even though Kaufmann discloses cylindrical segment 24 that
wraps around an axial portion of the piston rod to form a seal, the claim requires
more. Claim 1 requires that the pressure tube has an end with an end face
surrounding a central opening. The pressure tube being shaped at said end to form
an end wall. The end face facing radially inward to define the central opening.
The piston rod extends through the central opening to form a ring-shaped gap
between the piston rod and the end face. The claim additionally requires that a
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