NZ758223B2

NZ758223B2 - A bearing monitoring method and system

Info

Publication number: NZ758223B2
Application number: NZ758223A
Authority: NZ
Inventors: Iain Epps
Original assignee: Iain Epps
Filing date: 2018-05-10
Publication date: 2024-12-03

Abstract

This invention relates to a bearing monitoring method and system suitable for the monitoring of faults in rolling element bearings. The method and system utilize an acceleration sensor that is sensitive to both acceleration and housing strain and which has the effect of amplifying acceleration events that coincide with areas of the housing strain signal that correspond to bearing ball-pass events. The housing strain signal due to ball- pass events can be used to synchronise or otherwise modify the sampling of acceleration signals, or to determine bearing performance characteristics.

Claims

CLAIMS :

1. A bearing monitoring system comprising: i. a rolling element bearing housing; ii. a force sensor attached to the housing which generates output signals, 5 the force sensor comprising one or more sensor elements arranged to be sensitive to acceleration and strain; iii. a strain detection circuit which receives the output signals and generates strain signals representative of housing strain; iv. an acceleration detection circuit which receives the output signals and 10 generates acceleration signals representative of acceleration forces applied to the housing; and v. a processing circuit adapted to: use the strain signals to synchronise the acceleration signals to rolling element pass events; and 15 generate one or more signals indicative of bearing condition based on the synchronised acceleration signals.

2. A bearing monitoring system as claimed in claim 1 wherein the strain signals are used to window the acceleration signals and the windowed acceleration signals 20 are accumulated to generate one or more signals indicative of bearing condition.

3. A bearing monitoring system as claimed in any one of the preceding claims wherein the processing circuit accumulates both the strain and acceleration 25 signals.

4. A bearing monitoring system as claimed in any one of the preceding claims wherein the processing circuit determines bearing fault severity based on the separation between an entry event representative of where a rolling element 30 enters a fault region, and an exit event representative of where a rolling element exits a fault region.

5. A bearing monitoring system as claimed in any one of the preceding claims wherein the processing circuit determines the position of a fault based on a phase of the strain signal and a phase of events in the acceleration signal.

6. A bearing monitoring system as claimed in any one of the preceding claims wherein the force sensor is attached to the housing so as to enhance its sensitivity to housing strain. 10

7. A bearing monitoring system as claimed in any one of the preceding claims wherein the one or more sensor elements that comprise the force sensor is selected from piezoelectric sensors, electromagnetic sensors, MEMs (micro- electromechanical systems) sensors, other electromechanical sensors, optical sensors and electro-resistive sensors capable of sensing strain and/or 15 acceleration.

8. A method of monitoring the condition of a rolling element bearing via a sensor attached to a housing supporting the bearing, the sensor being sensitive to strain and acceleration, the method comprising: 20 i. developing a strain signal from the output of the sensor representing housing strain; ii. developing an acceleration signal from the output of the sensor representing housing acceleration forces; iii. using the strain signal to synchronise the acceleration signal to rolling 25 element pass events; and iv. determining bearing condition based on the synchronised acceleration forces.

9. A method as claimed in claim 8 wherein the strain signal is used to window the 30 acceleration signal and a plurality of windowed acceleration signals are accumulated to generate one or more signals indicative of bearing condition.

10. A method as claimed in any one of claims 8 to 9 wherein both the strain and acceleration signals are accumulated.

11. A method as claimed in any one of claims 8 to 10wherein bearing fault severity 5 is determined based on the separation between an entry event, representative of where a rolling element enters a fault region, and an exit event, representative of where a rolling element exits a fault region.

12. A method as claimed in any one of claims 8 to 11 wherein the position of a fault 10 is determined based on a phase of the strain signal and a phase of the acceleration signal.

13. A method as claimed in any one of claims 8 to 12 wherein bearing condition is determined by isolating acceleration events which have the same repetition 15 period as the strain signal, or the same repetition period as a known multiple of strain signal period.

14. A method as claimed in any one of claims 8 to 13 wherein bearing condition is determined by using known bearing geometry and a period between 20 acceleration events to determine defect width.

15. A method as claimed in any one of claims 8 to 14 wherein bearing condition is determined by using known bearing geometry and the phase of acceleration events with respect to the strain signal to determine a defect angular position.