Measurement of frictional torque of a directacting valvetrain using a shaft-to-shaft torque transducer to study the effect of Laser Surface Texturing on friction reduction

Abstract

The study of tribological applications requires measuring various parameters, including RPMs, friction, and wear. The useful information is sometimes not readily available in a measurement and requires further postprocessing to extract that information. In this research, a production engine test rig has been developed to study a direct-acting valvetrain’s tribological performance for various operating conditions. The measurement of the drive torque is carried out by using a shaft-to-shaft torque transducer. The total drive torque is a combination of geometric torque and frictional torque. The geometric torque is not affected by changes in parameters such as surface modification or lubricant chemistry but the frictional torque changes. We need to extract the frictional torque from the total drive torque to study the effect of any parameter or operating condition change on friction. As variation in frictional torque helps the tribologists to compare the performance of different parameter changes. This paper explains the complete procedure of measuring the experimental frictional torque from drive torque data. In this study, the frictional torque variation between an untextured and a textured tappet shim is studied for a direct acting cam tappet contact of a real production engine.