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The increasing use of gasoline direct injection (GDI) engines coupled with the implementation of new particulate matter (PM) and particle number (PN) emissions regulations requires new emissions control strategies. Gasoline particulate filters (GPFs) present one approach to reduce particle emissions. Although primarily composed of combustible material which may be removed through oxidation, particle also contains incombustible components or ash. Over the service life of the filter the accumulation of ash causes an increase in exhaust backpressure, and limits the useful life of the GPF. This study utilized an accelerated aging system to generate elevated ash levels by injecting lubricant oil with the gasoline fuel into a burner system. GPFs were aged to a series of levels representing filter life up to 150,000 miles (240,000 km). The impact of ash on the filter pressure drop and on its sensitivity to soot accumulation was investigated at specific ash levels.

It is well known that lubricating oil consumption (LOC) is much affected by the cylinder bore deformation occurring within internal combustion engines. There are few analytical reports, however, of this relationship within internal combustion engines in operation. This study was aimed at clarifying the relationship between cylinder bore deformation and LOC, using a conventional in-line four-cylinder gasoline engine. The rotary piston method developed by the author et al. was used to measure the cylinder bore deformation of the engine’s cylinder #3 and cylinder #4. In addition, the sulfur tracer method was applied to measure LOC of each cylinder. LOC was also measured by changing ring tension with a view to taking up for discussion how piston ring conforms to cylinder, and how such conformability affects LOC. Their measured results were such that the cylinder bore deformation was small in the low engine load area and large in the high engine load area.

The Engine-Out Particulate Matter (EOPM) was collected from a spark ignition engine operating in steady state using a heated quartz fiber filter. The samples were weighted to obtain an EOPMindex and were analyzed using Scanning Electron Microscopy. The EOP Mindex was not sensitive to the engine rpm and load. When the mixture is very rich (air equivalence ratio λ less than ∼ 0.7), the EOPM comprise mostly of soot particles from fuel combustion. In the lean to slightly rich region (0.8 < λ < 1.2), however, the EOPM are dominated by particles derived from the lubrication oil.

This paper deals with the friction performance results for various new concept piston skirt profiles. The program was conducted under the assumption that friction performance varies by the total amount of oil available at each crank angle in each stroke and the instantaneous distribution of the oil film over the piston skirt area. In previous papers [1,2] it was that lower friction designs would be expected to show higher skirt slap noise. This paper discusses the correlation between friction and skirt slap for each new concept profile design. Finally, this paper explains the friction reduction mechanism for the test samples for each stroke of the engine cycle by observing the skirt movement and oil lubrication pattern using a visualization engine.

This study has been conducted aiming at reductions of piston slap noise and piston friction loss, and effects of lubricating oil supply between the piston skirt and cylinder on diesel engine have been verified through a series of experiments. Namely, lubricating oil was supplied forcibly into the piston skirt from outside of engine, and its effects on the cylinder block vibration, piston friction force, slap motion and oil consumption have been measured. As a result, it has been verified that the supply of a small amount of oil (6mL/min) to the piston skirt reduces about 50 % of the block vibration caused by the piston slap motion in idling operation, and about 20 % of the piston friction loss in full load operation. Furthermore it has verified without giving any significant adverse effect on oil consumption.

The extent of oxidation of hydrocarbons desorbing from the oil layer has been measured directly in a hydrogen-fueled, spark-ignited engine in which the lubricant oil was doped with a single component hydrocarbon. The amount of hydrocarbon desorbed and oxidized could be measured simultaneously as the dopant was only source of carbon-containing species. The fraction oxidized was strongly dependent on engine load, hydrogen fuel-air ratio and dopant chemical reactivity, but only modestly dependent on spark timing and nitrogen dilution levels below 20 percent. Fast FID measurements at the cylinder exit showed that the surviving hydrocarbons emerge late in the exhaust stroke.

A reciprocating test apparatus was constructed in which the friction of a single piston ring against a liner segment was measured. The lubrication oil film thickness was also measured simultaneously at the mid stroke of the ring travel using a laser fluorescence technique. The apparatus development and operation are described. Results are presented from a test matrix consisting of five different lubrication oils of viscosity (at 30°C) ranging from 49 to 357 cP; at three mean piston speeds of 0.45, 0.89 and 1.34 m/s; and at three ring normal loading of 1.4, 2.9 and 5.7 MPa. At mid stroke, the oil film thickness under the ring was ∼0.5 to 4 μm; the frictional coefficient was ∼0.02 to 0.1. The frictional coefficient for all the lubricants tested increased with normal load, and decreased with piston velocity. Both mixed and hydrodynamic lubrication regimes were observed. The friction behaviors were consistent with the Stribeck diagram.

A method to collect and speciate the components of gasoline absorbed in the lubricant oil using gas chromatography has been developed. Samples were collected continuously from the piston skirt, baffle and sump in a Saturn engine. A long (18 hours) test was performed to determine the build up of hydrocarbons in the sump, and a shorter (25 min) test was performed to determine the build up of hydrocarbons in the piston skirt and baffle during engine warm-up. The first experiment showed that the total hydrocarbon concentration in the sump oil reached a steady state of about 1.35% mass fraction after 11 hours of engine operation. The relative concentration of individual fuel hydrocarbon species absorbed in the oil increases exponentially with boiling point. Most of the identified species in the oil consist of the heavy end aromatics. Similar compositions but lower concentrations were found for samples collected from the piston skirt during engine warm-up.

Exhaust-gas recirculation (EGR) causes the piston ring and cylinder liners of a diesel engine to suffer abnormal wear. The present study aimed at making clear the mechanism of wear which is induced by soot in the EGR gas. The piston ring has been chrome plated and the cylinder was made of boron steadite cast iron. Detailed observations of the ring sliding surfaces and that of the wear debris contained in lubricating oil were carried out. As a result, it was found that the wear of the top ring sliding surfaces identify abrasive wear without respect to the presence of EGR by steadite on the cylinder liner sliding surface. In addition, it is confirmed in a cutting test that soot mixed lubricating oil improved in performance as cutting oil. Based on these results, we proposed the hypothesis in the present study that ring wear is accelerated at EGR because abrasive wear increases due to a lot of soot mixed into lubricating oil improving the performance of lubricating oil as cutting oil.

The Wankel rotary engine is more compact than conventional piston engines, but its oil and fuel consumption must be reduced to satisfy emission standards and customer expectations. A key step toward this goal is to develop a better understanding of the apex seal lubrication to reduce oil injection while reducing friction and maintaining adequate wear. This paper presents an apex seal dynamics model capable of estimating relative wear and predicting friction, by modeling the gas and oil flows at the seal interfaces with the rotor housing and groove flanks. Model predictions show that a thin oil film can reduce wear and friction, but to a limited extent as the apex seal running face profile is sharp due to the engine kinematics.

In internal combustion engines, the majority of the friction loss associated with the piston takes place on the thrust side in early expansion stroke. Research has shown that the Friction Mean Effective Pressure (FMEP) of the engine can be reduced if proper modifications to the piston skirt, which is traditionally barrel-shaped, are made. In this research, an existing model was applied for the first time to study the effects of different oil supply strategies for the piston assembly. The model is capable of tracking lubricating oil with the consideration of oil film separation from full film to partial film. It is then used to analyze how the optimized piston skirt profile investigated in a previous study reduces friction.

Three-piece oil control rings (TPOCR) are widely used in the majority of modern gasoline engines and they are critical for lubricant regulation and friction reduction. Despite their omnipresence, the TPOCRs’ motion and sealing mechanisms are not well studied. With stricter emission standards, gasoline engines are required to maintain lower oil consumption limits, since particulate emissions are strongly correlated with lubricant oil emissions. This piqued our interest in building a numerical model coupling TPOCR dynamics and oil transport to explain the physical mechanisms. In this work, a 2D dynamics model of all three pieces of the ring is built as the main frame. Oil transport in different zones are coupled into the dynamics model. Specifically, two mass-conserved fluid sub-models predict the oil movement between rail liner interface and rail groove clearance to capture the potential oil leakage through TPOCR. The model is applied on a 2D laser induced fluorescence (2D-LIF) engine.

Due to increasing economic and environmental performance requirements of internal combustion engines, piston manufacturers now focus more on lower friction designs. One factor strongly influencing the friction behavior of pistons is the dynamic interaction between lubricating oil, cylinder bore and piston. Therefore, the dynamic effect of the oil film in the gap between the liner and piston has been studied, using a single cylinder engine equipped with a sapphire window. This single cylinder engine was also equipped with a floating liner, enabling real-time friction measurement, and directly linking the oil film behavior to friction performance of pistons.

This paper describes a measurement method using laser induced fluorescence we have developed for simple simultaneous measurements of piston ring oil film thickness at plural points for internal combustion engines. The findings obtained by the measurements of oil film thickness on both thrust and anti-thrust sides of the piston for a mono-cylinder compact diesel engine using this new measurement method are also discussed in this paper. One of main findings is that the oil film thickness of each ring on both sides differs markedly in terms of the absolute value and the stroke- to-stroke variation. It is found that this difference in oil film thickness is caused by the difference in the amount of lubricating oil supplied to the oil ring, and the effect is greater than that of engine speed or load.

The oil control ring (OCR) controls the supply of lubricating oil to the top two rings of the piston ring pack and has a significant contribution to friction of the system. This study investigates the two most prevalent types of OCR in the automotive market: the twin land oil control ring (TLOCR) and three piece oil control ring (TPOCR). First, the basis for TLOCR friction on varying liner roughness is established. Then the effect of changing the land width and spring tension on different liner surfaces for the TLOCR is investigated, and distinct trends are identified. A comparison is then done between the TLOCR and TPOCR on different liner surfaces. Results showed the TPOCR displayed different patterns of friction compared the TLOCR in certain cases.

The distribution of lubricating oil plays a critical role in determining the friction between piston skirt and cylinder liner, which is one of the major contributors to the total friction loss in internal combustion engines. In this work, based upon the experimental observation an existing model for the piston secondary motion and skirt lubrication was improved with a physics-based model describing the oil film separation from full film to partial film. Then the model was applied to a modern turbo-charged SI engine. The piston-skirt FMEP predicted by the model decreased with larger installation clearance, which was also observed from the measurements using IMEP method at the rated. It was found that the main period of the cycle exhibiting friction reduction is in the expansion stroke when the skirt only contacts the thrust side for all tested installation clearances.

In an engine system, the piston pin is subjected to high loading and severe lubrication conditions, and pin seizures still occur during new engine development. A better understanding of the lubricating oil behavior and the dynamics of the piston pin could lead to cost- effective solutions to mitigate these problems. However, research in this area is still limited due to the complexity of the lubrication and the pin dynamics. In this work, a numerical model that considers structure deformation and oil cavitation was developed to investigate the lubrication and dynamics of the piston pin. The model combines multi-body dynamics and elasto-hydrodynamic lubrication. A routine was established for generating and processing compliance matrices and further optimized to reduce computation time and improve the convergence of the equations. A simple built-in wear model was used to modify the pin bore and small end profiles based on the asperity contact pressures.