2134/13351
Christopher E. Baker
Christopher E.
Baker
Stephanos Theodossiades
Stephanos
Theodossiades
Homer Rahnejat
Homer
Rahnejat
Brian Fitzsimons
Brian
Fitzsimons
Influence of in-plane dynamics of thin compression rings on friction in internal combustion engines
Loughborough University
2013
Compression ring
In-plane dynamics
Modal response
Mixed regime of lubrication
Aerospace Engineering
Mechanical Engineering not elsewhere classified
Mechanical Engineering
2013-10-14 11:03:07
Journal contribution
https://repository.lboro.ac.uk/articles/journal_contribution/Influence_of_in-plane_dynamics_of_thin_compression_rings_on_friction_in_internal_combustion_engines/9573962
The compression ring-bore conjunction accounts for significant frictional parasitic losses relative to
its size. The prerequisite to improving the tribological performance of this contact is a fundamental
understanding of ring dynamics within the prevailing transient nature of regime of lubrication.
Studies reported thus far take into account ring-bore conformance, based on static fitment of the
ring within an out-of-round bore, whose out-of-circularity is affected by manufacturing processes,
surface treatment and assembly. The static fitment analyses presume quasi-static equilibrium
between ring tension and gas pressure loading with generated conjunctional pressures. This is an
implicit assumption of ring rigidity whilst in situ. The current analysis considers the global modal
behaviour of the ring as an eigenvalue problem, thus including its dynamic in-plane behaviour in the
tribological study of a mixed-hydrodynamic regime of lubrication. The results show that the contact
transit time is shorter than that required for the ring to reach steady state condition. Hence, the
conjunction is not only subject to transience on account of changing contact kinematics and varied
combustion loading, but also subject to perpetual ring transient dynamics. This renders the ring-bore
friction a more complex problem than usually assumed in idealised ring fitment analyses. An
interesting finding of the analysis is increased ring-bore clearance at and in the vicinity of top dead
centre, which reduces the ring sealing effect and suggests a possible increase in blow-by. The current
analysis, integrating ring in-plane modal dynamics and mixed regime of lubrication includes salient
features which are closer representation of practice, an approach which has not hitherto been reported in literature.