Appeal No. 1999-0519
Application 08/728,224
to or less than” the lower operating frequency of the shaft;2
and
then disposing a mass having a predetermined weight (W) in
combination with the rotating shaft “at said second order
critical frequency node, whereby said mass maintains said
adjusted first order critical frequency at a frequency equal
to or less than said lower operating frequency, thereby con-
trolling lateral vibration of said rotating shaft as said
2We understand from appellant’s specification that in a
typical shaft system, the second order critical frequency
would normally occur at a rotational frequency higher than the
upper operating frequency of the rotating shaft, so that the
operation of the shaft system is not affected thereby. How-
ever, it is common in many shaft systems for the first order
critical frequency to occur within the operating frequency
range, thereby introducing the potential for shaft instability
and undesirable vibratory characteristics. As noted on page 4
of the specifica- tion, an object of appellant’s invention is
to provide a method and apparatus for controlling lateral
vibration in a shaft system by shifting the first order
critical frequency of a rotating shaft out of an operational
frequency range of the shaft system, without changing the
second order critical frequency. Thus, with regard to appel-
lant’s method claim 1, we understand that the “first order
critical frequency” set forth in the preamble is one which
occurs within the operational frequency range of the rotating
shaft, while the “adjusted first order critical frequency” is
equal to or, more preferably, less than the lower operating
frequency of the rotating shaft.
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