Rotating shaft vibration monitor

A system for monitoring an effect of torque on a rotating shaft, comprising;

• a first plurality of detectable means circumferentially distributed along an outer surface of said rotating shaft at a first axial location thereof;
• a second plurality of detectable means circumferentially distributed at said equal intervals along the outer surface of said rotating shaft at a second axial location thereof, said second axial location being separated from said first axial location by a predetermined distance;
• first detecting means for outputting a pulse in response to each event wherein one of said first plurality of detectable means is located at a first predetermined angular position opposing said first detecting means, said pulses output by said first detecting means forming a first pulse train;
• second detecting means for outputting a pulse in response to each event wherein one of said second plurality of detectable means is located at a second predetermined angular position opposing said second detecting means, said pulses output by said second detecting means forming a second pulse train;
• processing means for computing a wave number of a torsional wave propagating axially in said rotating shaft in dependence on variations in a difference in phase angles between corresponding pulses of said first and second pulse trains, and
• first means for directing light onto said rotating shaft at said first axial location such that light reflected by said first detectable means impinges on said first detecting means and second means for directing light onto said rotating shaft at said second axial location such that light reflected by said second detectable means impinges on said second detecting means.

A system for monitoring an effect of torque on a rotating shaft, comprising:

• a first plurality of detectable means circumferentially distributed along an outer surface of said rotating shaft at a first axial location thereof;
• a second plurality of detectable means circumferentially distributed at said equal intervals along the outer surface of said rotating shaft at a second axial location thereof, said second axial location being separated from said first axial location by a predetermined distance;
• first detecting means for outputting a pulse in response to each event wherein one of said first plurality of detectable means is located at a first predetermined angular position opposing said first detecting means, said pulses output by said first detecting means forming a first pulse train;
• second detecting means for outputting a pulse in response to each event wherein one of said second plurality of detectable means is located at a second predetermined angular position opposing said second detecting means, said pulses output by said second detecting means forming a second pulse train;
• processing means for computing a wave number of a torsional wave propagating axially in said rotating shaft in dependence on variations in a difference in phase angles between corresponding pulses of said first and second pulse trains, wherein said processing means comprise means for quantizing the time intervals between corresponding pulses of said first and second pulse trains and means for determining the relative twist angle between first and second cross-sectional portions of said rotating shaft at said first and second axial locations respectively over time in dependence on said quantized time intervals, and
• means for displaying first and second wave patterns showing the variation of said relative twist angle over time for said first and second cross-sectional portions.

A method for monitoring an effect of torque on a rotating shaft, comprising the steps of:

• detecting the time at which predetermined circumferential portions of said rotating shaft at a first axial location thereof reach a first predetermined angular position;
• outputting a first electrical signal which varies as a function of detection of said predetermined circumferential portions at said first predetermined angular position;
• detecting the time at Which predetermined circumferential portions of said rotating shaft at a second axial location thereof reach a second predetermined angular position;
• outputting a second electrical signal which varies as a function of detection of said predetermined circumferential portions at said second predetermined angular position;
• computing a wave number of a torsional wave propagating axially in said rotating shaft in dependence on variations in a difference in phase angles between said first and second electrical signals, wherein said first electrical signal comprises a first train of electrical pulses and said second electrical signal comprises a second train of electrical pulses and said variations in a difference in phase angles are determined by quantizing the time intervals between corresponding pulses of said first and second pulse trains;
• and
• determining the relative twist angle between first and second cross-sectional portions of said rotating shaft at said first and second axial locations respectively over time in dependence on said quantized time intervals, and displaying first and second wave patterns showing the variation of said relative twist angle over time for said first and second cross-sectional portions.