Lubricant Degradation Studies Using a Single Cylinder Research Engine

Abstract

With increasing pressure on engine oil manufacturers to extend oil drain intervals and reduce fuel consumption, whilst changing the composition of fully formulated oils to meet new CEC, ILSAC and OEM specifications, there is ever increasing need to understand the effect of oil degradation on the operating conditions and tribological performance of engines. This poster presents mechanical changes made to a single cylinder research engine to enable the study of lubricant degradation, its transport and how this links to piston assembly tribology. A summary of the research undertaken using these changes and a sample of results obtained to date are also presented.

Bridging macroscopic lubricant transport and surface tribochemical investigations in reciprocating engines

“…1), as Lee et al [10] has shown. Watson et al [13] also showed that lubricant additive composition varied substantially from the sump, which has engine wear and deposit formation implications.…”

“…The rheology of the oil in the ring-pack region varies substantially from that of oil in the main enginepumping loop (Fig. 1), as Lee et al [10] has shown. Watson et al [13] also showed that lubricant additive composition varied substantially from the sump, which has engine wear and deposit formation implications.…”

“…Figure 1 shows a schematic of the oil-transport loops. Most of the oil circulates in the primary loop, and only a small quantity (a fraction of a millilitre [10] out of a total oil volume of a few litres for a passenger-car size cylinder) of oil resides in the ring-pack crevices.…”

“…Volatilization preferentially removes the lighter hydrocarbons from the system. Different lubricant rheology in the top-ring groove of a spark-ignition engine compared with that in the crankcase has been shown [10] experimentally using direct sampling techniques. Different metallic concentrations in the sump oil from that in the ring-pack oil have also been observed [13].…”