Abstract
The current work introduces a new semi-floating ring bearing (SFRB) system developed for improving the rotordynamic and vibration performance of automotive turbochargers (TCs) at extreme operation conditions, such as high temperature, severe external force excitation, and large rotor imbalance. The new bearing design replaces outer oil films, i.e., squeeze film dampers (SFDs), in TC SFRBs with wire mesh dampers (WMDs). This SFRB configuration integrating WMDs aims to implement reliable mechanical components, as an inexpensive and simple alternative to SFDs, with consistent and superior damping capability, as well as predictable forced performance. Since WMDs are in series with the inner oil films of SFRBs, experimentally determined force coefficients of WMDs are of great importance in the design process of TC rotor-bearing systems (RBSs). Presently, the measurements of applied static load and ensuing deflection determine the structural stiffnesses of the WMDs. The WMD damping parameters, including dissipated energy, loss factor, and dry friction coefficient, are estimated from the area of the distinctive local hysteresis loop of the load versus WMD displacement data recorded during consecutive loading-unloading cycles as a function of applied preload with a constant amplitude of motion. The changes in WMD loss factor and dry friction coefficient due to increases in preload are more significant for the WMDs with lower density. The present work shows, to date, the most comprehensive measurements of static load characteristics on the WMDs for application into small automotive TCs. More importantly, the extensive test measurements of WMD deflection versus increasing static loads will aid to anchor predictions of future computation model.
Highlights
Automotive turbochargers (TCs) provide pressurized air into internal combustion engines (ICEs) to increase engine output power and combustion efficiency with reduced NOx and CO2 emissions [1]
In semi-floating ring bearing (SFRB), the inner fluid film acts as a hydrodynamic fixed geometry plain journal bearing while the outer fluid film acts as a squeeze film damper (SFD)
The current study presents average values of the identified parameters from three non-sequential and independent measurements of push-pull loads and wire mesh dampers (WMDs) displacements
Summary
Automotive turbochargers (TCs) provide pressurized air into internal combustion engines (ICEs) to increase engine output power and combustion efficiency with reduced NOx and CO2 emissions [1]. Bearing systems in automotive TCs must be simple, compact, reliable, and inexpensive while providing acceptable rotordynamic and noise, vibration, and harshness (NVH) characteristics. The journal bearing (i.e., the floating ring) is not stationary; it is free to float and move, but the anti-rotation pin prevents its rotation. In SFRBs, the inner fluid film acts as a hydrodynamic (i.e., self-acting) fixed geometry plain journal bearing while the outer fluid film acts as a squeeze film damper (SFD). SFRBs are prone to show large subsynchronous rotordynamic responses over extended operating
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