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Gas chromatographic methods for analyzing hydrocarbon species in vehicle exhaust emissions were compared in terms of their collection efficiency, detection limit, repeatability and number of species detected using cylinder gas and tailpipe emission samples. The main methods compared were a Tenax cold trap injection (TCT) method (C5-C12 HCs) and a cold trap injection (CTI) method (C2-C4 HCs; C5-C12 HCs). Our own direct (DIR) method was used to confirm the collection efficiencies. Both methods yielded good results, but the CTI method showed low collection efficiency for some C2-C4 HCs. Measurement of individual species is needed with this method for accurate analysis of tailpipe emissions. Both the CTI method and the TCT method combined with the DIR method for determining C2-C4 HCs yielded nearly the same ozone specific reactivity values for the NMHC species analyzed.

A model has been developed for estimating the oil vaporization rate from the cylinder liner of a reciprocating engine. The model uses input from an external cycle simulator and an external liner oil film thickness model. It allows for the change in oil composition and the change in oil film thickness due to vaporization. It also estimates how the passage of the compression and scraper rings combine with the vaporization to influence the steady-state composition of the oil layer in the upper ring pack. Computer model results are presented for a compression-ignition engine using a range of liner temperatures, several engine speeds, and two different oils. Vaporization is found to be highly dependent on liner temperature and steady-state oil composition. The steady-state oil composition near the top of the cylinder is found to be significantly different than the composition of the oil near the bottom of the cylinder.

An aerodynamic model of the entrainment of the head wall quench layer during blowdown and exhaust of an internal combustion engine has been developed. The model may be used to calculate the time resolved concentration and mass flowrate of hydrocarbons (HC) in the exhaust, from a knowledge of engine geometry and operating conditions. It predicts that the area As from which HC are swept will be proportional to the cube root of the ratio of the quench layer thickness δq to the thickness of the viscous boundary layer δv. Since the mass of HC emitted is proportional to the product of the HC density ρHC, the area As and the thickness δq, the HC emissions will be proportional to the product ρHC δq4/3 and this is the most important factor determining the emissions.

As a new generation sports car engine to lead the field in the 1990s, a 3.0 liter, 60°V, type 6 cylinder, 4 cam, 24 valve engine (VG30DETT) has been developed to achieve the utmost in high performance levels and reliability. it has been mounted on the new model 300ZX and announced in the North America and Japanese markets. The VG30DETT engine is based on the previous VG30DE engine (the engine mounted on the former model 300ZX designed for the market in Japan). The main components, the major driving and the lubrication systems including such parts as the crank shaft,con-rod, cylinder block, piston, exhaust manifold, and oil pan of the VG30DE were thoroughly reviewed and revised. The VG30DETT engine is the result of redesigning the structure of the engine itself and its parts and components to assure durability under, high-level performance requirements.

A novel engine management strategy for achieving fast catalyst light-off without the use of an exhaust air pump in a port-fuel-injected, spark ignition engine was developed. A conventional 4-cylinder engine was operated with three cylinders running rich and the fourth one as an air pump to supply air to the exhaust manifold. Under steady-state cold coolant conditions, this strategy achieved near total oxidation of CO and HC with sufficiently retarded spark timing, resulting in a 400% increase in feedgas enthalpy flow and a 90% reduction in feedgas HC emissions compared to conventional operation. The strategy was also evaluated for crank starts. Using the existing engine hardware, implementing the strategy resulted in a reduction in catalyst light-off time from 28.0 seconds under conventional operation to 9.1 seconds.

A twin-land oil control ring (TLOCR) model is used to evaluate TLOCR friction and the results are compared to the experiment measurement in a single cylinder floating liner engine under motoring condition. The model is based on a correlation between the hydrodynamic pressure and film thickness, which is generated using a deterministic model. The well-known three-regime lubrication is predicted with the model for ring with different ring tensions under various engine running conditions. A good match is found for the model and experiment results.

A complete one-dimensional mixed lubrication model has been developed to predict oil film thickness and friction of the piston ring-pack. An average flow model and a roughness contact model are used to consider the effects of surface roughness on both hydrodynamic and boundary lubrication. Effects of shear-thinning and liner temperature on lubricant viscosity are included. An inlet condition is applied by considering the unsteady wetting location at the leading edge of the ring. A ‘film non-separation’ exit condition is proposed to replace Reynolds exit condition when the oil squeezing becomes dominant. Three lubrication modes are considered in the model, namely, pure hydrodynamic, mixed, and pure boundary lubrication. All of these considerations are crucial for studying the oil transport, asperity contact, and friction especially in the top dead center (TDC) region where the oil control ring cannot reach.

Technologies for improving the fuel economy of gasoline engines have been vigorously developed in recent years for the purpose of reducing CO2 emissions. Increasing the compression ratio is an example of a technology for improving the thermal efficiency of gasoline engines. A significant issue of a high compression ratio engine for improving fuel economy and low-end torque is prevention of knocking under a low engine speed. Knocking is caused by autoignition of the air-fuel mixture in the cylinder and seems to be largely affected by heat transfer from the intake port and combustion chamber walls. In this study, the influence of heat transfer from the walls of each part was analyzed by the following three approaches using computational fluid dynamics (CFD) and experiments conducted with a multi-cooling engine system. First, the temperature rise of the air-fuel mixture by heat transfer from each part was analyzed.

This paper describes the use of a modified quasi-dimensional spark-ignition engine simulation code to predict the extent of cycle-to-cycle variations in combustion. The modifications primarily relate to the combustion model and include the following: 1. A flame kernel model was developed and implemented to avoid choosing the initial flame size and temperature arbitrarily. 2. Instead of the usual assumption of the flame being spherical, ellipsoidal flame shapes are permitted in the model when the gas velocity in the vicinity of the spark plug during kernel development is high. Changes in flame shape influence the flame front area and the interaction of the enflamed volume with the combustion chamber walls. 3. The flame center shifts due to convection by the gas flow in the cylinder. This influences the flame front area through the interaction between the enflamed volume and the combustion chamber walls. 4. Turbulence intensity is not uniform in cylinder, and varies cycle-to-cycle.

There have been strong demands recently for reductions in the fuel consumption and exhaust emissions of diesel engines from the standpoints of conserving energy and curbing global warming. A great deal of research is being done on new emission control technologies using direct-injection (DI) diesel engines that provide high thermal efficiency. This work includes dramatic improvements in the combustion process. The authors have developed a new combustion concept called Modulated Kinetics (MK), which reduces smoke and NOx levels simultaneously by reconciling low-temperature combustion with pre-mixed combustion [1, 2]. At present, research is under way on the second generation of MK combustion with the aim of improving emission performance further and achieving higher thermal efficiency [3]. Reducing heat rejection in the combustion chamber is effective in improving the thermal efficiency of DI diesel engines as well as that of MK combustion.

This paper concerns research on an emission control system aimed at reducing emission levels to well below the ULEV standards. As emission levels are further reduced in the coming years, it is projected that measurement error will increase substantially. Therefore, an analysis was made of the conventional measurement system, which revealed the following major problems. 1. The conventional analyzer, having a minimum full-scale THC range of 10 ppmC, cannot measure lower concentration emissions with high accuracy. 2. Hydrocarbons are produced in various components of the measurement system, increasing measurement error. 3. Even if an analyzer with a minimum full-scale THC range of 1 ppmC is used in an effort to measure low concentrations, the 1 ppmC measurement range cannot be applied when the dilution air contains a high THC concentration. This makes it impossible to obtain highly accurate measurements. 4.

Since the stable operating region of a gasoline-fueled HCCI engine is limited to the part load condition, a mode change between SI and HCCI combustion is required, which poses an issue due to the difference in combustion characteristics. This report focuses on the combustion characteristics in the transitional range. The combustion mode in the transitional range is investigated by varying the internal EGR rate, intake air pressure, and spark advance timing in steady-state experiments. In this parametric study, stable SI-CI combustion is observed. This indicates that the combustion mode transition is possible without misfiring or knocking, regardless of the speed of variable valve mechanism which includes VVA, VVEL, VTEC, VVL and so on, though the response of intake air pressure still remains as a subject to be examined in the actual application.

Technologies for improving the fuel economy of gasoline engines have been vigorously developed in recent years for the purpose of reducing CO2 emissions. Increasing the compression ratio for improving thermal efficiency and downsizing the engine based on fuel-efficient operating conditions are good examples of technologies for enhancing gasoline engine fuel economy. A direct-injection system is adopted for most of these engines. Direct injection can prevent knocking by lowering the in-cylinder temperature through fuel evaporation in the cylinder. Therefore, direct injection is highly compatible with downsized engines that frequently operate under severe supercharging conditions for improving fuel economy as well as with high compression ratio engines for which susceptibility to knocking is a disadvantage.

The thermal environment in the automotive engine compartment is expected to become increasingly severe in the years ahead owing to the installation of a large-size manifold catalyst to reduce exhaust emissions, among other factors. This will make it even more important to analyze the engine compartment layout in terms of heat flow considerations at the design conceptualization stage of a new vehicle. In this research, a flow analysis program called DRAG4D was applied to find the flow velocity distribution and ambient air temperature distribution in the engine compartment during driving, idling and after the engine was turned off. This original program developed at Nissan takes into account the effects of the energy balance and buoyancy, and provides a practical level of prediction accuracy. The time required to create an analytical model and perform the computations has been shortened by using an automatic grid generation function, based on a solid model, and experimental equations.

The aim of this study is to gain a better understanding of the mechanism of knocking with respect to flame propagation behavior based on 3D simulations conducted with the Universal Coherent Flamelet Model. Flame propagation behavior under the influence of in-cylinder flow was analyzed on the basis of the calculated results and experimental visualizations. Tumble and swirl flows were produced in the cylinder by inserting various baffle plates in the middle of the intake port. A comparison of the measured and calculated flame propagation behavior showed good agreement for various in-cylinder flow conditions. The results indicate that in-cylinder flow conditions vary the flame propagation shape from the initial combustion period and strongly influence the occurrence of knocking.

An automatic matching method for engine control parameters is described which can aid efficient development of new engine control systems. In a spark-ignition engine, fuel is fed to a cylinder in proportion to the air mass induced in the cylinder. Air flow meter characteristics and fuel injector characteristics govern fuel control. The control parameters in the electronic controller should be tuned to the physical characteristics of the air flow meter and the fuel injectors during driving. Conventional development of the engine control system requires a lot of experiments for control parameter matching. The new matching method utilizes the deviation of feedback coefficients for stoichiometric combustion. The feedback coefficient reflects errors in control parameters of the air flow meter and fuel injectors. The relationship between the feedback coefficients and control parameters has been derived to provide a way to tune control parameters to their physical characteristics.

With the development of downsized spark ignition (SI) engines, low-speed pre-ignition (LSPI) has been observed more frequently as an abnormal combustion phenomenon, and there is a critical need to solve this issue. It has been acknowledged that LSPI is not directly triggered by autoignition of the fuel, but by some other material with a short ignition delay time. It was previously reported that LSPI can be caused by droplets of lubricant oil intermixed with the fuel. In this work, the ignition behavior of lubricant component containing fuel droplets was experimentally investigated by using a constant volume chamber (CVC) and a rapid compression and expansion machine (RCEM), which enable visualization of the combustion process in the cylinder. Various combinations of fuel compositions for the ambient fuel-air mixture and fractions of base oil/metallic additives/fuel for droplets were tested.

This paper provides an overview of spark-ignition engine unburned hydrocarbon emissions mechanisms, and then uses this framework to relate measured engine-out hydrocarbon emission levels to the processes within the engine from which they result. Typically, spark-ignition engine-out HC levels are 1.5 to 2 percent of the gasoline fuel flow into the engine; about half this amount is unburned fuel and half is partially reacted fuel components. The different mechanisms by which hydrocarbons in the gasoline escape burning during the normal engine combustion process are described and approximately quantified. The in-cylinder oxidation of these HC during the expansion and exhaust processes, the fraction which exit the cylinder, and the fraction oxidized in the exhaust port and manifold are also estimated.

To meet future particle mass and particle number standards, gasoline vehicles may require particle control, either by way of an exhaust gas filter and/or engine modifications. Soot levels for gasoline engines are much lower than diesel engines; however, non-combustible material (ash) will be collected that can potentially cause increased backpressure, reduced power, and lower fuel economy. The purpose of this work was to examine the ash loading of gasoline particle filters (GPFs) during rapid aging cycles and at real time low mileages, and compare the filter performances to both fresh and very high mileage filters. Current rapid aging cycles for gasoline exhaust systems are designed to degrade the three-way catalyst washcoat both hydrothermally and chemically to represent full useful life catalysts. The ash generated during rapid aging was low in quantity although similar in quality to real time ash. Filters were also examined after a low mileage break-in of approximately 3000 km.

An analysis method for characterizing fuel behavior during spark-ignition engine starting has been developed and applied to several sets of start-up data. The data sets were acquired from modern production vehicles during room temperature engine start-up. Two different engines, two control schemes, and two engine temperatures (cold and hot) were investigated. A cycle-by-cycle mass balance for the fuel was used to compare the amount of fuel injected with the amount burned or exhausted as unburned hydrocarbons. The difference was measured as “fuel unaccounted for”. The calculation for the amount of fuel burned used an energy release analysis of the cylinder pressure data. The results include an overview of starting behavior and a fuel accounting for each data set Overall, starting occurred quickly with combustion quality, manifold pressure, and engine speed beginning to stabilize by the seventh cycle, on average.