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The rotary engine provides high power density compared to piston engine, but one of its downside is higher oil consumption. A model of the oil seals is developed to calculate internal oil consumption (oil leakage from the crankcase through the oil seals) as a function of engine geometry and operating conditions. The deformation of the oil seals trying to conform to housing distortion is calculated to balance spring force, O-ring and groove friction, and asperity contact and hydrodynamic pressure at the interface. A control volume approach is used to track the oil over a cycle on the seals, the rotor and the housing as the seals are moving following the eccentric rotation of the rotor. The dominant cause of internal oil consumption is the non-conformability of the oil seals to the housing distortion generating net outward scraping, particularly next to the intake and exhaust port where the housing distortion valleys are deep and narrow.

The rotary engine provides high power density compared to piston engine, but one of its downside is higher oil consumption. In order to better understand oil transport, a laser induced fluorescence technique is used to visualize oil motion on the side of the rotor during engine operation. Oil transport from both metered oil and internal oil is observed. Starting from inside, oil accumulates in the rotor land during inward motion of the rotor created by its eccentric motion. Oil seals are then scraping the oil outward due to seal-housing clearance asymmetry between inward and outward motion. Cut-off seal does not provide an additional barrier to internal oil consumption. Internal oil then mixes with metered oil brought to the side of the rotor by gas leakage. Oil is finally pushed outward by centrifugal force, passes the side seals, and is thrown off in the combustion chamber.

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.

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.

To understand the effects of crevices on the engine-out hydrocarbon emissions, a series of engine experiments was carried out with different piston crevice volumes and with simulated head gasket crevices. The engine-out HC level was found to be modestly sensitive to the piston crevice size in both the warmed-up and the cold engines, but more sensitive to the crevice volume in the head gasket region. A substantial decrease in HC in the cold-to-warm-up engine transition was observed and is attributed mostly to the change in port oxidation.

A method for determining the flame contour based on the flame arrival time at the fiber optic (FO) spark plug and at the head gasket ionization probe (IP) locations has been developed. The experimental data were generated in a single-cylinder Ricardo Hydra spark-ignition engine. The head gasket IP, constructed from a double-sided copper-clad circuit board, detects the flame arrival time at eight equally spaced locations at the top of the cylinder liner. Three other IP's were also installed in the cylinder head to provide additional intermediate data on flame location and arrival time. The FO spark plug consists of a standard spark plug with eight symmetrically spaced optical fibers located in the ground casing of the plug. The cylinder pressure was recorded simultaneously with the eleven IP signals and the eight optical signals using a high-speed PC-based data acquisition system.

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.

The adoption of turbine engines for automotive power plants has been hampered by the high cost, high leakage and high wear rate of present designs of ceramic-matrix regenerators. Proposals are made and analyzed here for design directions to achieve substantial improvements in all three areas. These include lower-cost extruded and pressed matrices; and clamping seals coupled with incremental movement of the rotary-regenerator matrix.

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.

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.