A systematic analysis of the friction losses on bearings of modern turbocharger

Abstract

In the article, a novel test rig for determining the friction losses of modern turbocharger is presented. The friction torque of the bearing of turbocharger can be measured direct and stationary at any speed up to 100,000 min–1 by the friction test rig developed by the Ostfalia, University of Applied Science (UAS). Since 2010, over 50 turbochargers were measured on the test bench in extensive measurement series. The results give valuable and new insights of the influence of the next parameters on the bearing friction losses: oil temperature, oil pressure, thrust force and oil flow rate. Furthermore, a comparison between the different bearing types (semi-floating, full floating and ball bearings) was performed. The main observations and results are discussed in the scientific article.

Design of the turbocharger bearing arrangement to increase the overall efficiency of the combustion engine

“…The journal bearings were designed to support the longer shaft, with pressures exceeding the twice the existing condition. The design concepts focused on decreasing the efficiency losses by improving rotor dynamic stability and pressure distribution [10,24]. The journal bearings were designed in two parts, journal and the steel backing.…”

Experimental Study of Systems and Oils for Direct Cooling of Electrical Machine

“…Figure 7 shows the no-load losses obtained for a variation in glycol-water temperature ranging from 25 °C to 85 °C and for a constant flow rate of 720 l/h. Figure 7 No-load losses for different water-cooling temperatures For a given cooling temperature, the mechanical power at no-load can be approximated by a quadratic form [18] depending on the driving speed of the machine.…”

“…For a speed of 14 000 rpm, a decrease in the mechanical no-load power of about 600 W is observed for an increase in water cooling from 25 °C to 85 °C. This decrease can be explained by the reduction in mechanical losses in the bearings and seals with the increase in temperature [18]. In addition, when the temperature increases, the magnetic flux induced by the magnets decreases and leads to a decrease in iron losses [10].…”

“…The main observation made for the comparison of fluids is that the viscous friction losses are mainly related to the viscosity of the fluid in contact with the shaft line [18]. In fact, lower viscosity implies lower losses.…”