Tapered Roller Bearings with Improved Efficiency and High Power Density for Automotive Transmissions

Abstract

<div class="htmlview paragraph">This paper is focusing on the performance enhancement of the tapered roller bearings supporting the transfer shaft in a push belt type Continuously Variable Transmission (CVT). It also provides an objective comparison, based on test results, with the fixed/floating ball bearings alternative arrangement. The influence of different design parameters such as cup and cone race profile, roller length / diameter ratio, surface finish etc., is quantified in the analytical and experimental investigation. The bearings power loss is calculated and measured for operating conditions that are relevant in a vehicle fuel economy cycle.</div> <div class="htmlview paragraph">Additional specific aspects related to the use of tapered roller bearings, such as setting and mounting procedures, are discussed under similar considerations. The paper contains a system analysis of the transfer shaft interacting with the variator output shaft and with the differential. Shaft and gear mesh deflections are evaluated in the general context of system stiffness for improved durability and NVH behavior.</div> <div class="htmlview paragraph">The conclusions of this paper can be extended to the tapered roller bearings employed in other types of automotive transmissions; the CVT application was selected only for its higher emphasis on fuel economy.</div>