Turbocharger Bearings

Hannu Jääskeläinen

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Abstract: Bearings are a critical component of the turbocharger that affects its durability and reliability. Modern turbocharger bearings can be split into two main types: hydrodynamic journal bearing systems and ball bearing systems. Other potential bearing technologies include foil air bearings and active magnetic bearings.

Design Considerations

Turbocharger bearings systems are an often overlooked but critical component of the turbocharger. A properly designed bearing system can spell the difference between a turbocharger design that operates efficiently and effectively over the life of the engine and one that is plagued by durability problems. Turbocharger bearing systems are also evolving in the face of increased pressure to reduce engine fuel consumption and emissions. Newer engines often demand higher turbocharger efficiencies that in in many cases, can be partially achieved by reducing losses due to the bearing system.

The turbocharger bearing system must be tolerant of [2538]:

In an era of increased pressure to reduce emissions and fuel consumption, reducing bearing friction can play a critical role in improving cold start emissions and fuel economy. Also, as engine oil viscosities become lower, either through the use of low viscosity oils or dilution by fuel during post injections for DPF regeneration, turbocharger bearing systems must adapt to maintain rotor-dynamic stability and to avoid increased wear [3414].

Modern commercial turbocharger bearing systems can be split into two principal types: hydrodynamic journal bearing systems and ball bearing systems. Hybrid systems are also possible that combine journal and ball bearings.