VIBRATION MONITORING DEVICE USING ACCELEROMETER TO MEASURE DISPLACEMENT

• US 3,859,847 A
• Filed: 09/06/1972
• Issued: 01/14/1975
• Est. Priority Date: 09/06/1972
• Status: Expired due to Term

• Current Assignee: David C. Ronemus
• Original Assignee: David C. Ronemus
• Inventors: Ronemus, David C.
• Primary Examiner(s): Gill, James J.
• Application Number:
  US05/286,623
• Time in Patent Office: 860 Days
• Field of Search: 73/70,71,71.1,71.2,71.4 33/147N,174E,174Q
• US Class Current: 73/660
• CPC Class Codes: G01H 1/003 of rotating machines G01H1/10 takes precedence

Abstract

The vibration of a rotating shaft is measured with a unitary shaft rider biased against the circumference of the shaft with a coil spring. The shaft rider is relatively light weight for true tracking at high frequencies of vibration and the accelerometer used to measure the absolute value of the vibration is disposed upon the top of the shaft rider close to the rotating shaft. The acceleration signal from the accelerometer is provided to an electronics module at the top or outside portion of a bearing cap in which the rider, spring and accelerometer are disposed. This is adapted for measuring frequency of vibrations over a wide range and for measuring low frequency vibration. The rider has a very low propensity for tangential movement, which if present could give a false indication of vibration.

Claims

1. A vibration monitoring device for monitoring the radial vibratory motion of a rotating shaft in an apparatus relative to an inertial frame of reference, where the rotating surface of the shaft is radially spaced from the surface of the apparatus in a plane generally transverse to the axis of the shaft by a distance which is relatively large when compared with the diameter of the shaft, where a communicating channel of relatively small crosssection when compared with the diameter of the shaft is present between the apparatus surface and the shaft surface for thereby providing access to the shaft surface from the apparatus surface for monitoring the vibratory motion of the shaft, comprising:

indicating means disposed outside of said channel;

an absolute vibration measuring transducer disposed in said channel and electrically connected to said indicating means for converting mechanical movement which is provided to said transducer into an electrical signal which signal is provided to said indicating means to give an indication of the magnitude of said mechanical movement; and

a unitary shaft rider disposed in said channel but not affixed thereto comprising a generally homogeneous structural material, one portion of which is disposed in physical contact with said transducer and generally is the only means of support for said transducer and another portion which is generally disposed against said shaft for the purpose of transmitting a portion of the mechanical vibratory movement of said shaft relative to said inertial frame of reference at any instant of time to said transducer, said entire transducer being generally only radially movable relative to said shaft in said channel during coversion of said mechanical motion to said electrical signal.

2. The combination as claimed in claim 1 wherein said shaft rider has an axis generally transverse to the tangent of the outer surface of said shaft at that portion of said shaft where said rider is tracking at any instant of time, a shaft rider guide means disposed in said channel, said guide means allowing said shaft rider to move generally unimpeded in the direction of said axis in response to said vibratory motion in said shaft but generally impeding rotary movement of said rider about said rider axis.

3. A vibration monitoring device for monitoring the radial vibratory motion of a rotating shaft in an apparatus relative to an inertial frame of reference, where the rotating surface of the shaft is radially spaced from a surface of the apparatus in a plane generally transverse to the axis of the shaft by a distance which is relatively large when compared with the diameter of the shaft, where a communicating channel of small cross-section when compared with the diameter of the shaft is present between the apparatus surface and the shaft surface for thereby providing access to the shaft surface from the apparatus surface for monitoring the vibratory motion of the shaft, comprising:

indicating means disposed outside of said channel;

AN absolute vibration measuring transducer disposed in said channel and electrically connected to said indicating means for converting mechanical movement which is provided to said transducer into an electrical signal which signal is provided to said indicating means to give an indication of the magnitude of said mechanical movement;

a shaft rider member disposed in said channel but not affixed thereto one portion of which is disposed in physical contact with said transducer and generally is the only means of support for said transducer and another portion of which is generally disposed against said shaft for the purpose of transmitting a portion of the mechanical vibratory movement of said shaft relative to said inertial frame of reference at any instant of time to said transducer, said entire transducer being generally only radially movable relative to said shaft in said channel during conversion of said mechanical motion to said electrical signal; and

coil spring means, one portion of which is held generally fixed relative to said apparatus surface and another portion of which is disposed against said transducer to provide a force of spring compression to thereby cause said shaft rider member which is in physical contact with said transducer to generally track said rotating shaft.

4. The combination as claimed in claim 3 wherein said shaft rider has an axis generally transverse to the tangent of the outer surface of said shaft at that portion of said shaft where said rider is tracking at any instant of time, shaft rider guide means disposed in said channel, said guide means allowing said shaft rider to move generally unimpeded in the direction of said axis in response to said vibratory motion in said shaft but generally impeding rotary movement of said rider about said rider axis.

5. The combination as claimed in claim 4 wherein said shaft rider member comprises generally homogeneous structural material.

6. The combination as claimed in claim 5 wherein said guide means comprises a cylindrical tube, said cylindrical tube having disposed therein at least a portion of said coil spring means, at least a portion of said transducer and at least a portion of said shaft rider for protecting and guiding said last three mentioned elements.

7. A vibration monitoring device for monitoring the radial vibratory motion of a rotating shaft in an apparatus relative to an inertial frame of reference, where the rotating surface of the shaft is radially spaced from a surface of the apparatus in a plane generally transverse to the axis of the shaft by a distance which is relatively large when compared with the diameter of the shaft, where a communicating channel of relatively small cross-section when compared with the diameter of the shaft is present between the apparatus surface and the shaft surface for thereby providing access to the shaft surface from the apparatus surface for monitoring the vibratory motion of the shaft, comprising:

indicating means disposed outside of said channel;

an absolute vibration measuring transducer disposed in said channel and electrically connected to said indicating means for converting mechanical movement which is provided to said transducer into an electrical signal which signal is provided to said indicating means to give an indication of the magnitude of said mechanical movement;

a shaft rider member disposed in said channel but not affixed thereto, one portion of which is disposed in physical contact with said transducer and generally is the only means of support for said transducer and another portion of which is disposed against said shaft for the purpose of transmitting a portion of the mechanical vibratory movement of said shaft relative to said inertial frame of reference at any instant of time to said transducer, said shaft rider having an axis generally transverse to the tangent of the outer surface of said shaft at that portion of said shaft where said shaft rider is tracking at any instant of time, saId entire transducer being generally only radially movable relative to said shaft in said channel during conversion of said mechanical motion to said electrical signal; and

shaft rider guide means disposed in said channel, said guide means allowing said shaft rider to move generally unimpeded in the direction of said axis in response to said mechanical vibratory movement in said shaft but generally impeding rotary movement of said rider about said rider axis.

8. A vibration monitoring device for monitoring the radial vibratory motion of a rotating shaft in an apparatus relative to an inertial frame of reference, where the rotating surface of the shaft is radially spaced from a surface of the apparatus in a plane generally transverse to the axis of the shaft by a distance which is relatively large when compared with the diameter of the shaft where a communicating channel of relatively small cross-section when compared with the diameter of the shaft is present between the apparatus surface and the shaft surface for thereby providing access to the shaft surface from the apparatus surface for monitoring the vibratory motion of the shaft, comprising:

indicating means disposed outside of said channel;

an absolute vibration measuring transducer disposed in said channel and electrically connected to said indicating means for converting mechanical movement which is provided to said transducer into an electrical signal which signal is provided to said indicating means to give an indication of the magnitude of said mechanical movement;

a shaft rider disposed in said channel but not affixed thereto, one portion of which is disposed in physical contact with said transducer and generally is the only means of support for said transducer and another portion of which is disposed against said shaft for transmitting a portion of the mechanical movement of said shaft relative to said inertial frame of reference at any instant of time to said transducer, said entire transducer being generally only radially movable relative to said shaft in said channel during conversion;

of said mechanical motion to said electrical signal; and

spring means affixed at one end thereof to said channel and at another end thereof to said shaft rider for tracking said shaft rider on said shaft.

9. The combination as claimed in claim 8 comprising a protective housing for said transducer, said spring means comprising a coil spring disposed against said protective housing.

10. A vibration monitoring device for monitoring the radial vibratory motion of a rotating shaft in an apparatus, where the rotating surface of the shaft is radially spaced from a surface of the apparatus in a plane generally transverse to the axis of the shaft by a distance which is relatively large when compared with the diameter of the shaft, where a communicating channel of relatively small cross-section when compared with the diameter of the shaft is present between the apparatus surface and the shaft surface for thereby providing access to the shaft surface from the apparatus surface for monitoring the vibratory motion of the shaft, comprising:

indicating means disposed outside of said channel;

a transducer disposed in said channel and electrically connected to said indicating means for converting mechanical movement provided to said transducer into an electrical signal which signal is provided to said indicating means to give an indication of the magnitude of said mechanical movement;

a shaft rider member disposed;

in said channel but not affixed thereto comprised of generally homogeneous structural material, one portion of which is disposed in physical contact with said transducer and generally is the only means of support for said transducer and another portion of which is generally disposed against said shaft for the purpose of transmitting said mechanical vibratory movement of said shaft at any instant of time to said transducer, said entire transducer being generally only radially movaBle relative to said shaft in said channel during conversion of said mechanical motion to said electrical signal, said shaft rider having an axis generally transverse to the tangent of the outer surface of said shaft at that portion of said shaft where said rider is tracking at any instant of time;

coil spring means, one portion of which is held generally fixed relative to said apparatus surface and another portion of which is disposed against said transducer to provide a force of spring compression to thereby cause said shaft rider member which is in physical contact with said transducer to generally track said rotating shaft; and

a cylindrical tubular shaft rider guide means disposed in said channel, said guide means allowing said shaft rider to move generally unimpeded in the direction of said axis in response to said mechanical movement in said shaft but generally impeding movement of said rider in a direction transverse to said axis, said guide means communicating with the surface of said shaft, said guide means having disposed therein at least a portion of said coil spring means, at least a portion of said transducer and at least a portion of said shaft rider for protecting said last three mentioned elements, said guide means having disposed therein a recess, said rider having disposed thereon a protrusion a portion of which is disposed in said recess, said recess being oriented to cooperate with said protrusion to allow said rider to move substantially unimpeded in the direction of said axis but not to allow said rider to rotate substantially about said axis.

11. A vibration monitoring device for monitoring the radial vibratory motion of a rotating shaft in a bearing mount, where the rotating surface of the shaft is radially spaced from a surface of the bearing mount in a plane generally transverse to the axis of the shaft by a distance which is relatively large when compared with the diameter of the shaft, where a communicating channel of relatively small cross-section when compared with the diameter of the shaft is present between the bearing mount surface and the shaft surface for thereby providing access to the shaft surface from the bearing mount surface for monitoring the vibratory motion of the shaft comprising:

indicating means disposed outside of said channel;

an accelerometer disposed in said channel and electrically connected to said indicating means for converting mechanical movement provided to said accelerometer into an electrical signal which signal is provided to said indicating means to give an indication of the magnitude of said mechanical movement;

a shaft rider disposed in said channel but not affixed thereto comprising an integral protective housing at the upper portion thereof for enclosing said accelerometer, said shaft rider being disposed adjacent to said shaft for transmitting a portion of the mechanical movement of said shaft at any instant of time to said accelerometer; and

a coil spring disposed in compressible relationship between said channel wall and said integral protective housing of said shaft rider to bias said shaft rider against said shaft.