Investigations on the power losses and thermal behaviour of rolling element bearings

Abstract

Temperature levels and distributions in rolling element bearings (REBs) depend on many parameters such as load, rotational speed, lubricant, etc. In this context, the understanding of power loss and heat generation mechanisms is a major issue especially for REBs operating at high speeds, since they largely control the component behaviour, its capacity to operate at high temperatures, and ultimately its integrity. It is commonly accepted that the power losses in high-speed bearings can be divided into (a) sliding friction losses in the contacts between the rolling elements and races, (b) sliding friction losses (Couette flow) at the cage/race and cage/rolling elements contacts, (c) oil churning losses for splash and dip lubrication. However, there is no general agreement about two other sources namely rolling friction and drag forces, but it seems that whatever the chosen model be the resulting total power losses are equivalent. In the present study, a thermal network approach is presented in order to estimate the temperatures at different locations within a thrust angular ball bearing. Several power loss distributions inside the REBs are considered and their influences on different power losses and on temperatures along with the important role of the oil—air mixture are highlighted.

Transient Thermal Modeling of Ball Bearing Using Finite Element Method

“…As previously described, TNM is based on analytical equations solved for a discrete number of nodes that represent the main components, media and mechanisms of heat exchange that characterize a bearing chamber. In accordance with the approach presented in Pouly [3], the following additional assumptions/limitations:…”

“…Harris [2] shows a steady-state thermal resistance approach on a roller bearing assembly, highlighting the limitations. Pouly et al [3], again using the TNM, focus on the power losses in high-speed bearings, with emphasis on the rolling friction and drag forces losses, aside from other sources of power losses. The referred study demonstrates that the overall power losses obtained are comparable to other approaches when adjustments are made on the air fraction in the lubricant.…”

“…The study also highlights the sensitivity of temperature distribution that is dependent on heat source localisation. This is shown to vary from 70% to 100% and dependent on how the power losses are defined when predicting the heat absorbed by the oil [3].…”

Experimental investigation and thermal analysis of coupler-rocker ball bearing

“…The heat generated in the bearing is dissipated to the surrounding through modes of heat transfer. Most researchers [5,6,8,12,[15][16][17][18] designed thermal resistance network model to calculate the heat transfer through conduction and convection from the bearing. This method comprises of the network of resistances constructed among different components of the test bearing assembly.…”

Two Phase Flow Pattern of Injection Lubrication in High Speed Bearings

“…There are many researches on the lubrication of rolling bearings, but they are based on the study of the pressure distribution and oil film thickness of single-phase flow [3][4][5]. Coe et al [6][7] through the temperature field analysis and experiment of bearing. Parker [8][9] compares the heat production, temperature and lubricating oil of three kinds of angular contact ball bearings, and presents an empirical formula for oil content: (1) Among them, XCAV is the volume fraction of lubricant in the bearing cavity, which is used to characterize the degree of mixing of oil and gas, W is the oil supply, N is the bearing speed, and d m is the bearing pitch diameter.…”