Appeal No. 1997-0287
Application 08/263,034
magnetic thrust bearing, which turbo compressor is
conventionally supported by oil bearings. A complete
magnetic bearing system can be thereby achieved to
realize an oil-free design and, hence, an economical
turbo compressor reduced in running cost, maintenance
cost or the like.
Thus, Miura discloses an active magnetic thrust bearing system
and fluid thrust balancing system in combination with a turbo
compressor, where the fluid thrust balancing system is for the
purpose of reducing the thrust on the active magnetic thrust
bearings. Miura also discloses that the fluid thrust
balancing controller and active magnetic thrust bearing
controller are coupled together.
One of ordinary skill in the art of designing turbo
machinery would have recognized that the same problem of
variations in axial thrust exists in turbo machinery having
active magnetic bearings such as Andres and would have been
motivated to employ a fluid thrust balancing system as taught
in Miura in addition to the active magnetic thrust bearings to
offset the thrust load on the thrust bearings. The
combination of Andres and Miura appears sufficient to
establish a prima facie case of obviousness. We consider
Appellants' arguments before deciding whether a prima facie
case has been made.
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