Tribology of power train systems

Tribology of power train system

Effect of cylinder deactivation on tribological performance of piston compression ring and connecting rod bearing

Thermo-mixed-hydrodynamics of compression rings and big-end bearings are presented. Frictional losses under normal engine operating conditions for a gasoline engine and those with cylinder deactivation (CDA) are predicted. With CDA, the combustion chamber pressure increases in the active cylinders, whilst some residual pressure remains in the deactivated ones. For the former, the increased in-cylinder temperatures reduce viscous friction, whilst reducing the load carrying capacity, promoting increased boundary interactions. In deactivated cylinders, lower contact temperatures yield increased viscous friction. Overall, a 5% improvement in expended fuel is expected with the application of CDA. However, 10% of these gains are expended due to increased friction. The study demonstrates the need to consider total system effects when introducing new technologies such as CDA

A tribo-multibody model for valve train kinematic analysis, quasi-statics of lubricated contact and assessment of structural integrity

A tribo-multibody model for valve train kinematic analysis, quasi-statics of lubricated contact and assessment of structural integrit

A review of some tribo-dynamics phenomena from micro- to nano-scale conjunctions

The paper provides some highlights in the developments of theories of lubrication and contact mechanics from early pioneering works of Reynolds and Hertz to the establishment of elastohydrodynamic phenomenon by Ertel and Grubin. Some historical discourse is made on the development of elastohydrodynamic theory in the past 6 decades, with particular attention paid to the contact of rolling element bearings. The steady miniaturisation of devices has led to progressively smaller contacts of individual features with lighter load share and diminishing gaps. The ultra-thin films are supported by interaction potentials that significantly deviate from bulk continuum behaviour of lubricating films, with insignificant contributions due to viscous–elastic nature of contacts. Using the same theme of rolling element contacts, the paper highlights the action of some of these dominant forces at close range