Influence of Grease in Mechanical Efficiency of Constant Velocity Joints

The required Fuel Economy improvement to meet increasing CAFE standards and the global trend to reduce CO₂ emissions has prompted automakers to look at new technologies and optimize current technologies. One area of focus is the reduction of mechanical energy losses in driveline systems, which translate to less fuel consumption. Even though the driveline and chassis components account for only 2% (approximately) of the total mechanical losses in passenger vehicles, automakers have shown interest in maximizing the mechanical efficiency of driveline systems. A key component of any driveline system is the Halfshaft (HS), consisting of two Constant Velocity Joints (CVJ’s). The efficiency of CVJ’s is dependent on the joint architecture, angle of operation, transmitted torque, rotational speed and the grease selected for lubrication. Premium Tripots have the highest mechanical efficiency among CVJ’s. Ball-type joints tend to have lower efficiency. However, with the proper grease selection, the mechanical efficiency of conventional fixed joints can be as high as the efficiency of joints with more complex geometry, where it matters the most, at typical running angles under 10°.