Search

Reduction in friction ensures fuel economy, control on emissions and durability of components in internal combustion engines. A modern gasoline internal combustion engine was instrumented to determine the friction values at the cam–roller interface considering the effects of surface treatment and engine operating state. A series of tests under different operating speeds and lubricant inlet temperatures were undertaken using both an original surface roller and a Wonder Process Craft (WPC) surface-treated engine roller. The results clearly revealed a substantial reduction in friction magnitude for the WPC surface-treated engine roller in comparison to the original roller while operating under similar conditions, indicating their strong potential for employment in engines. An increase in friction with the rise in temperature was also observed for both types of rollers, whereas increased lubricant entraining velocity due to higher operating speed had the opposite impact. A considerable reduction in frictional drive torque ranging from 8% to 28% was observed by employing the WPC-treated roller in comparison to original/untreated roller at various operating conditions, which signifies the strong potential for employment of WPC surface treatment in the roller/follower valve train engines. [ABSTRACT FROM AUTHOR]

Reduction in friction ensures fuel economy, control on emissions and durability of components in internal combustion engines. A modern gasoline internal combustion engine was instrumented to determine the friction values at the cam–roller interface considering the effects of surface treatment and engine operating state. A series of tests under different operating speeds and lubricant inlet temperatures were undertaken using both an original surface roller and a Wonder Process Craft (WPC) surface-treated engine roller. The results clearly revealed a substantial reduction in friction magnitude for the WPC surface-treated engine roller in comparison to the original roller while operating under similar conditions, indicating their strong potential for employment in engines. An increase in friction with the rise in temperature was also observed for both types of rollers, whereas increased lubricant entraining velocity due to higher operating speed had the opposite impact. A considerable reduction in frictional drive torque ranging from 8% to 28% was observed by employing the WPC-treated roller in comparison to original/untreated roller at various operating conditions, which signifies the strong potential for employment of WPC surface treatment in the roller/follower valve train engines.

In this study, a numerical investigation is presented to calculate the flash temperature at the cam–tappet junction area using different easy-to-use theoretical models available in the literature. Flash temperature models use many assumptions and simplifications. Consequently, it will be beneficial to compare flash temperatures obtained from different models. It has been observed that the results obtained from different models vary substantially. Detailed reasoning has been provided for the variation in results. It has been found that high flash temperature is present in direct acting valve trains. The flash temperature caused the total friction force to decline. In light of experimental evidence, it can be deduced that the mixed friction force model shows less sensitivity to temperature. [ABSTRACT FROM AUTHOR]

The performance and durability of tribological components in roller follower valve train is governed mainly by the roller rotational behaviour. Pure rolling of roller on the camshaft surface is essential to achieve the optimum valve train efficiency. The increase in roller slip can lead to high valve train power loss due to increase in sliding friction and can increase the wear rate of mating surfaces of camshaft and roller. In this research work, a modern gasoline engine having end-pivoted roller finger follower valve train configuration has been instrumented to investigate the effects of Wonder Process Craft surface treatment on roller slip. Comprehensive test programme has been undertaken at transient camshaft speeds by employing the New European Drive Cycle under different oil temperatures and pressures. Remarkable reduction in roller slip was recorded for Wonder Process Craft surface treated roller as compared to the original unmodified roller indicating its strong potential of employment in engine valve train. The test rig, surface treatment of roller, instrumentation, experimentation, results and discussion have been presented in detail in this paper. [ABSTRACT FROM AUTHOR]