Multilobe floating ring bearings for automotive turbochargers

Floating ring bearings are commonly applied in automotive turbocharger machinery because they are inexpensive and are able to reduce unbalance-induced vibrations. This type of bearings, however, can become a source of noise due to oil whirl-induced sub-synchronous vibrations. This study examined whether the concept of a floating ring bearing with a lobed clearance might be a solution to diminish oil whirl induced vibrations. A numerical model is developed to evaluate the dynamic behavior of the coupled rotor-bearing system. The resulting run-up simulations have been validated with experimental results of turbocharger run-up measurements. The results of the plain floating ring design and the multilobe floating ring design are compared, showing that the multilobe floating ring bearing design is superior in suppressing both synchronous and sub-synchronous vibrations at the cost of a slight increase in friction losses. Hence, multilobe floating ring bearings are an attractive alternative to plain floating ring bearings for automotive turbocharger applications.