Experimental Measurement of Roller Slip with change in Lubricant Inlet Pressure in the End-Pivoted Roller Follower Assembly

Abstract

A recent experimental study in SMME, NUST (Khurram M. et al., 2014) has revealed roller slip in the end-pivoted roller followers with lubricant having a direct impact on the roller slip. This thesis reports a research that further investigates the relationship between the lubricant pressure and the roller slip between the end-pivoted rollers and cam-lobes. The study has been carried out on Toyota Prius 1NZK engine in with minimum test bed alterations to investigate the relationship between lubricant pressure and roller slip by simulating the original lubrication system of the engine and using Group 4 base oil with a viscosity of 4 cSt. It has been concluded that with the rise in the inlet lubrication pressure in the end-pivoted roller followers, the Hydraulic Lash Adjuster forces the roller onto the cam-lobe. There is in an increase in asperity conditions as boundary and EHL lubrication regimes tend to be more dominant. As a result of this increase in pressure, roller speed increases compared to that at lower pressures. This subsequently results in a decrease in roller slippage. This study reveals that end pivoted roller followers are more efficient at higher lubricant inlet pressure. A unique system developed by (Khurram M. et al., 2014) to measure roller slip, using extremely small Giant Magnetoresistive (GMR) ADL chip and a small alnico magnet, has been incorporated in the study the details of which have also been reported. Detailed description of the entire analysis including the experimental setup, test procedures and the results has been published in this document along with a thorough explanation of the units under consideration and their working principals.