Monitoring of lubrication and wear in-situ by triboelectrifi cation under grease lubrication

The stable operation of friction pairs is one of the
most critical factors to maintain the stable operation of
mechanical equipment. The real-time monitoring of lubrication
state of the friction pair is very important to ensure the normal
operation of machinery and realize early warning of wear failure,
but it is also a big challenge. In this article, a new lubrication in
situ monitoring system is designed, which can monitor the
lubrication and wear state of friction pairs through
triboelectrification. The current acquisition module and friction
coefficient acquisition module are integrated into a high vacuum
hydrodynamic oil film thickness measuring instrument to explore
the intrinsic relationship between triboelectricity and friction
coefficient curves. When severe wear occurs, the oil film at the
interface of the friction pair is no longer complete, and the accumulated triboelectric charge at the interface of the friction pair
breaks down the air and causes discharge, the friction current suddenly increases from nanoampere level to microampere level. The
time node when discharge occurs at the steel ball interface is well consistent with the time node when the friction pair suffers
serious wear. According to the corresponding relationship between the triboelectric current and the friction and wear status of the
friction pair, an early wear warning monitoring system is designed to monitor the operating status of the friction pair in real time
through triboelectric signals. When the mechanical friction pair is worn, the early warning system will send out sound and light
alarm signals and send real-time warnings to the mobile terminal through the Internet of Things, providing a new and reliable
method for real-time monitoring of friction and wear of grease-lubricated machinery.