Analyzing Ball Bearing Capacitance Using Single Steel Ball Bearings

Abstract

A precise modeling of the capacitance of rolling element bearings is of increasing significance over the last years, e.g. in the context of bearing damage estimation in electric drives. The complexity of a steel bearing as an electrical network makes reliable validation of calculation models under realistic operating conditions nearly impossible. A way to reduce complexity in yet realistic conditions is the use of hybrid bearings with a single steel rolling element. This helps to measure only one current path through the bearing at a time and thus, gives a much clearer picture of the contact capacitance of rolling elements in and out of the load zone. The usage of different materials comes with different thermal expansion coefficients and different elasticities, which cause a significant change in load distribution. For the first time, this work considers both of these effects in calculation and validates them with corresponding experiments using single steel ball bearings.

A Review on Sensor‐Integrating Machine Elements

“…The shortcomings of the phenomenological model ( 1) accompanied by measurements by Jablonka et al [226] gave rise to include also the contributions of the unloaded rolling contacts in the capacitance network of a rolling bearing. [23,227] In the context of the digitization of industry, the demand on data of technical systems and processes is on a constant rise especially for rolling element bearings. [228] As stated above, the bearing's capacitance and therefore impedance depends on the lubrication film thickness and the Hertzian area.…”

“…[232] Capacitive lubrication film thickness measurements are since then utilized for the analysis of steel on steel contacts in the EHD regime. [226,227,233] Initial studies were conducted to better understand, model and predict the behavior of rolling bearings. [23,[234][235][236]239] The improved electric modeling of rolling element bearings enables their sensorial use.…”

“…[ 226 ] gave rise to include also the contributions of the unloaded rolling contacts in the capacitance network of a rolling bearing. [ 23,227 ]…”

Towards White-Box Modeling of Sensory-Utilized Rolling Bearings

“…Then, the threedimensional position of the inner ring in relation to the outer ring is varied till the equilibrium of forces is found. More details on the derivation of the load distribution model can be found in [7].…”

“…are currently being improved [2,3,4]. Thus, influences on the capacitance, which were previously represented by rather inaccurate constant influence factors [5,6], could be replaced for the point contact by phenomenological equations for the respective operating state, [3,4,7]. The electrical impedance of rolling bearings in fluid film lubrication depends on the capacitance of the rolling contacts.…”