Appeal No. 97-3071
Application 08/484,729
498, 504, 190 USPQ 214, 218 (CCPA 1976).
Here, the appellant in the specification states that, in
order to reduce wear on the piston bore surface (i.e., the
surface of the bore or cylinder in which the piston
reciprocates), the piston should be provided with an “extended
curvature” having a radius which is of “sufficient” magnitude
to provide “continuous, tangential cooperation” between the
extended curvature and the surface of the bore in which it
reciprocates (see, e.g., page 13, lines 6-12; page 14, lines
11-17). These portions of the specification also state that
the “extended curvature” may be only on an extreme end portion
or continue the entire length of the piston. Page 13 of the
specification also states that
The continuous, tangential cooperation is
preferably of a conjugate nature, such that a
rolling motion occurs between the piston 38 and the
piston bore surface 32, as opposed to a sliding,
discontinuous, non-uniform motion. This cooperation
reduces wear on the piston bore surface 32 of the
cylinder block 14, by reducing the Hertzian or
contact stresses present from the “cocked” position
of the piston 38 within the piston bore 26, as the
piston 38 reciprocates and simultaneously rotates
within the piston bore 26 of the cylinder block 14.
While the instant invention contemplates a range of
radial dimensions to achieve the desired wear
reduction function, a radius R in the range of
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