Abstract
Wear of the journal bearings in a diesel engine is usually caused by asperity contact. Increased contact potential is caused by the asperity contact between the journal bearing and the shell. This paper analyzes the relationship between the contact potential and asperity contact and presents a method based on contact potential to monitor the bearing wear caused by asperity contact. A thermo-elastic hydrodynamic lubrication (THL) model of the journal bearing on the test bench was established and was verified by measuring its axis orbit. The asperity contact proportion was calculated based on this THL model, and its relationship with the measured contact potential was determined. The main contribution of this paper is to present a new method for monitoring the lubrication conditions of journal bearings in a diesel engine based on contact potential. The results showed that (a) when the minimum oil film thickness was less than 5 μm, asperity contact occurred between the bearing shell and the journal, which led to a sharp increase in contact pressure and a rapid increase in friction power consumption. Further, (b) there was a positive correlation between contact potential and asperity contact. The contact potential was greater than 0.75 mv when asperity contact occurred. These results proved that asperity contact could be accurately monitored using the contact potential, and the feasibility of using the contact potential to monitor the lubrication condition of a bearing was verified.
Highlights
25% of total friction losses in machines are caused by bearings, especially in certain high-power internal combustion engines, where the proportion of the total loss may reach as high as40% [1]
To study bearing wear monitoring based on a contact potential method, a single-factor fault simulation test is needed
Studies have shown that the lubrication state of the journal bearings in a diesel engine is a state of mixed lubrication between hydrodynamic lubrication and dry friction
Summary
25% of total friction losses in machines are caused by bearings, especially in certain high-power internal combustion engines, where the proportion of the total loss may reach as high as. Taking into account the time dependence of temperature in lubricant film, Tucker predicted the thermal design problem for a generic two-axial groove bearing [4]. These studies are steady-state analyses of bearing lubrication that did not consider the influence of external load changes. The relationship between the contact voltage, asperity contact, minimum oil film, and axis orbit was not further analyzed. To study bearing wear monitoring based on a contact potential method, a single-factor fault simulation test is needed. The contact potential could reflect whether the bearing journal and shell were experiencing asperity contact and whether the bearing had entered the mixed lubrication condition. The contact potential could be used to monitor the lubrication condition of the journal bearing
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
