P.M. Lee

Extraction and tribological investigation of top piston ring zone oil from a gasoline engine

Abstract With tightening emission regulations, increased expected fuel economy, and longer drain intervals impacting on lubricant formulation, greater understanding of how oil degrades in an automotive engine is becoming ever more important. Equally significant is the effect that this degraded lubricant has on the tribological operation of the engine, particularly its overall internal friction and component wear In a previous paper, four tests to degrade oil in a single cylinder engine were reported [1]. These tests were set up such that the lubricating oil was degraded in the ring pack before returning to the sump, where it was sampled and chemical and rheological analysis undertaken. This paper reports the extension of this work using the same Hydra engine and describes how oil has additionally been extracted from the rear of the top piston ring during engine operation. This extracted oil has then been subjected to similar analysis as the sump oil samples in the previous tests, along with additional analysis to look at the tribological properties of the oil using tribometers. The results clearly show significant differences in the rheological, tribological, and chemical properties of the fresh oil and used sump oil samples when compared with the top ring zone (TRZ) oil samples, particularly the effect of load on the levels of volatiles present in the TRZ samples and their effect on traction and friction coefficient values during tribological testing.

Tribometer investigation of the frictional response of piston rings with lubricant contaminated with the gasoline engine biofuel ethanol and water

Ethanol is considered a potential long-term replacement for gasoline but information on the impact of ethanol on engine lubricant performance is scarce. Therefore, it is of prime importance to investigate the effect of ethanol on lubricants and engines that currently operate on gasoline. A bench-top test programme was undertaken on a modified Plint TE77 reciprocating tribometer to simulate the piston ring and cylinder wall interface. The Taguchi statistical experimental design method was used to quantify the effect of ethanol and the associated water contamination on friction with a commercially available fully formulated lubricant. Control factors and potential interactions were selected based on the TE77 capability and typical gasoline engine operating conditions. The statistical results show that while independently ethanol does not significantly contribute to friction reduction, the independent contribution from water is moderate when compared with the combined effect of ethanol and water. The water–temperature and load–speed interactions provide a small contribution to friction reduction while the ethanol–load and temperature–load interactions contribute moderately to the same.

The degradation of lubricants in gasoline engines: Development of a test procedure to evaluate engine oil degradation and its consequences for rheology

Tests have been undertaken to study the effects of engine parameters and lubricant blends on oil degradation and engine components. A single cylinder spark ignition research engine was used for this work. The cam shaft was run on fully formulated oil and the crank and piston ring pack on the test oils. Samples were extracted from the sump, whilst the engine was running under controlled conditions, and rheological and chemical analysis data obtained from these samples. The methodology behind the testing and the engine set up is presented, as are results for the viscosity, sump carbonyl concentration and the end of test component condition for the four tests undertaken. Comparisons between the oil blends, engine parameters and results are discussed before conclusions are drawn and areas for further work highlighted.

Lubricant Degradation Studies Using a Single Cylinder Research Engine

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.Copyright

An innovative integrated approach to testing motorcycle drive chain lubricants

An innovative integrated approach to the testing and comparison of motorcycle drive chain lubricants is presented. This is a novel way of testing the lubricant by using loaded operating chains and sprockets. A test rig has been designed to operate chains and sprockets in a clean environment and allow direct comparison between different lubricants. The advantage of this method over previous techniques is that it allows the differentiation of lubricants in a more controlled operating environment and evaluates the overall lubricant performance as opposed to individual properties. The lubricants tested were a wax spray, PTFE spray and drip fed light oil. The test rig allowed measurement of the power saved by the lubricant in running the chains and sprockets. Chain length and component masses were also taken before and after running the chains and sprockets under load on the test rig. The results clearly show that any lubricant is preferable to none. The drip fed oil provided the greatest power saving and wear protection between the chain rollers and pins and the spray lubricants provided the highest level of protection between the rollers and sprockets.

The Tribological and Chemical Analysis of Top Ring Zone Samples of Fully Formulated Oil Taken From a Four Stroke Gasoline Engine

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 the new CEC, ILSAC and OEM specifications, there is an ever increasing need to understand the effect of oil degradation on the operating conditions and tribological performance of engines [1]. This work samples oil from the rear of the top piston ring of an engine during the first 15 minutes from cold start and operating at steady state under three different loads. These samples, used 40 hour sump oil and fresh oil have been subjected to tribological tests and chemical analysis.Copyright