| Characterization of the lubrication regimes and quantification of the frictional losses are very important factors for the design of durable IC engines with an improved fuel economy. The purpose of the current study is to develop a tribology test rig that allows for the direct measurement of the instantaneous friction force between the piston-assembly and the cylinder liner. In addition, the primary and secondary motions of the piston are directly measured by a tri-axial miniature accelerometer. The experimental results have been used herein to assess the variations of the friction force and the lubrication regimes of the piston-assembly during the running-in period of the engine. Moreover, the effects of oil viscosity and engine speed on the lubrication regimes of the piston-assembly have been examined. In addition, coefficient of friction curves at top-dead-center (TDC), bottom-dead-center (BDC) and locations of maximum piston speed during the up-stroke and down-stroke have been generated based on the Stribeck curve. Furthermore, the data corresponding to the instantaneous friction force and piston speed were used to calculate the oil film thickness throughout the engine cycle. |
