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Autoignition for most fuel-air mixtures in engines is preceded by relatively slow chemical changes. These changes are the main area of interest in this contribution, since a better control of the autoignition process in homogeneously charged motored engines may become potentially more viable through a better understanding of the reactions that lead to autoignition. An approach to modify the partial oxidation process is by changing the composition of the charge through a deliberate recirculation of some of the exhaust gases back into the cylinder. These recycled gases, when not fully cooled, can influence the autoignition process thermally. They may also contain small concentrations of active chemical species that could influence kinetically the partial oxidation processes of the engine.

A progressive reduction in the permitted level of phosphorus in lubricating oils, coupled with concern to maintain engine and transmission durability, means that it is becoming increasingly important to understand the detailed mechanism of antiwear additive behavior. This paper describes a new experimental technique, which is able to measure both the thickness and distribution of antiwear additive films in rolling/sliding contacts. This enables the kinetics of antiwear film build-up to be investigated and the influence of the reaction film on friction and wear to be monitored. In the current paper, this technique is used to compare the film-forming behavior of ash-containing and ashless antiwear additives.

“Without lubricants, all the machines in the whole world would grind to a halt”. This often used sentence, summarises rather well the increasingly important role of lubrication in our modern world in constant evolution.

This paper describes the design, development and operation of a digital electronic piston telemetry system. A feature is the multiplicity of operating modes, including two-way communication. The system has been demonstrated to work with thermocouples and accelerometers embedded in the piston of a very small engine at speeds of over 2000rev/m. The piston-mounted components can be fitted to a piston as small as 80mm diameter, and the size is reduced with every modification as smaller more powerful electronic components become available. Typical results are quoted in the paper

As emission regulations for off-road engines become more and more stringent, alternative fuel off-road engines are being developed rapidly. This paper studies a closed-loop controlled LPG system, which was developed and tested on four lawn and garden engines. The four engines studied are Kohler 18hp, Kohler 13 hp, Briggs & Stratton 6 hp, and Briggs & Stratton 5hp engines, which power Toro walk-behind commercial lawn mowers, John Deere lawn tractors, John Deere walk-behind commercial lawn mowers, and Toro walk-behind commercial lawn mowers, respectively. All engines are four-stroke, spark-ignited and air-cooled. The fuel management system is an air valve based closed-loop controlled dedicated LPG system. The emissions and durability test results are presented. It was found that all engines operating on propane had significantly lower exhaust emissions than those of gasoline baselines.

A swirl-type injector is commonly used for the gasoline direct injection IC engines. To control and optimize the engine combustion, analyses of mixture formation process inside the cylinder are quite important. In this study, an evaluation of a DDM (Discrete Droplet Model) including breakup and evaporation sub-models has been made by making comparisons between the calculation and measurement. In the calculation, two kinds of initial conditions were tested; one was from empirical expressions and the other was from calculated results using a VOF (Volume Of Fluid) model that had a feature to examine the free fluid surface of a liquid fuel spray. As a result, the authors have found that a DDM can basically explain the spray formation process. However, much further modification of the breakup model and initial conditions would be required to have a quantitatively good agreement between the calculation and measurement

The fuel consumption of heavy duty diesel engines is of great importance to fleet operators, since fuel can contribute up to 30% of the operating costs. This paper discusses the differences between fuel economy oils for heavy duty diesel engines and passenger car engines. A simple model is then presented showing how the reduced friction due to the use of fuel economy lubricants (both in the engine and the transmission) can lead to fuel consumption benefits. By including realistic losses due to air resistance and tyre rolling resistance, the model can predict fuel consumption benefits under different speed and load conditions that are in reasonable agreement with the benefits found in carefully controlled field trials.

Organotypic cultures of precision-cut rat lung slices are exposed three hours to 5 dilutions of a continuous exhaust flow. The exhausts from three fuelings are tested (filtered and not): gazole, gazole/RME mixture (70 % / 30%) and RME. Different parameters are assessed: ATP and GSH (cell viability), TNFα production (proinflammatory response) and nucleosomes (apoptosis). After exposure, the ATP level is only modified by the highest concentrations of gazole/RME or RME exhausts (filtered and not); the GSH level is decreased for each of the concentrated filtered exhausts. Moreover, only the whole gazole exhaust leads to a modification of TNFα production. At last, the whole gazole exhaust leads to an increase of slice nucleosome level in a dose-dependent way; RME supplementation or filtration significantly attenuates this effect.

The effect of the Swirl Control Valve (SCV) on the in-cylinder flow characteristics was studied using LDA measurement in a single cylinder four-valve spark ignition engine with a SCV. Mean velocity, root-mean-square (rms) velocity fluctuation, and frequency structure of the velocity fluctuation were analyzed to illustrate flow features under the SCV open and closed conditions. The results show that when the SCV is open, large-scale flow structure in the cylinder is mainly tumble vortex, which will distort and break up during the late stage of the compression stroke. The rms velocity fluctuation increases during the compression process and reaches its maximum at certain crank angle before TDC. Larger scale eddies and lower frequency structures in the flow field become more near the end of compression process due to breakup of the tumble. The rms velocity fluctuation in the combustion chamber is roughly uniform at the end of the compression process.

The deterioration of the friction reducing properties of engine oils containing molybdenum dithiocarbamates (MoDTCs) in service was studied. A quantitative analysis of MoDTCs and zinc dithiophosphates (ZDTPs) remaining in aged oils revealed that ZDTPs were consumed faster than MoDTCs. The consumption rate of ZDTPs was slow in the presence of MoDTCs and peroxide-decomposing antioxidants. The frictional properties of aged oils were evaluated with a reciprocating friction tester (SRV tester). The friction coefficient measured with the SRV tester was correlated to the properties of the aged oils, such as the TAN increase, TBN, and concentration of remaining ZDTPs.

For environmental and economical reasons, reduction of fuel consumption is becoming a major concern for car and truck manufacturers and customers. Analysis of consumer way of using their cars indicates, that it is by working on low temperature and low engine rotating speed that benefits given by the lubricant can be optimized. Analysis of customers way of using their trucks indicates that the engine is mainly working at stabilized temperature, in hydrodynamic conditions; in such conditions (for exemple highway), the reduction of fuel consumption coming from the engine lubricant is rather low, compared with passenger car applications. On that basis, specific rig tests have been developed to help the lubricant formulator. Each of these tests is specifically designed, for different engine friction area study: valve train, rings/liner, crankshaft bearings. The correlation between engine friction on each area and fuel consumption reduction is discussed.

With Euro III emissions standards requiring a 50% reduction in current diesel car emissions from January 1st 2000, there is a need to improve fuel consumption and thus reduce exhaust emissions. One of the ways this is being addressed is by the introduction of lower viscosity crankcase oils and by the use of friction modifiers within these oils. The resulting reduced engine friction contributes to improved fuel economy and should also aid engine cold start ability. To investigate the cold start abilities of different crankcase oils, a matrix consisting of six different oil formulations was tested at -20°C, - 25°C and -30°C in a two litre four cylinder diesel engine. The tests were conducted using a dynamometer, with the engine being driven by the dynamometer at nominal cranking speed for 30 seconds and then increased to cold idle speed for a further 30 seconds.

Historically, fuel cost conscious customers have tended to purchase diesel passenger cars. However, with increasing competition from alternative fuels and lean burn and direct injection gasoline fuelled engines, diesel engined vehicles currently face tough challenges from the point of fuel economy and emissions. In gasoline engines, low viscosity friction modified oils have demonstrated their potential for reducing internal engine friction and thus improving fuel economy, without adversely effecting engine durability. These fuel economy improvements have led to the introduction of such a low viscosity friction modified 5W-30 oil as the initial and service fill for the majority of Ford products sold in Europe. The trend towards even lower viscosities continues. To assess the potential benefits and issues of moving to 5W-20 in diesel engines, a short pilot study has been conducted using a Ford 1.8l direct injection diesel engine.

The effect of sampling conditions on the diesel exhaust aerosol characteristics has been studied so far with the application of Electrostatic Classifiers under steady state conditions. This paper aims at examining the same effects with application of an Electrical Low Pressure Impactor under transient engine operating conditions. Explanation of the results obtained takes into account the different operational characteristics of this new technique (recorded magnitude, size range and resolution). The study confirms particle formation in the dilution tunnel and downstream of a DPF and also coagulation of liquid particles in the tunnel. However, separation of the liquid particle phase has led to modification of the aerosol properties in a direction which may be conversely recorded by instruments based on different operation principles.

Measurements of exhaust emissions were conducted for six alternative diesel fuels in a 2.2L, direct-injection diesel engine. Triplicate 13-mode, steady-state test sequences were performed for each fuel, as well as an ASTM D975 low sulfur No. 2 diesel (2DLS) control fuel, which served as the baseline. The alternative fuels include California Reference fuel, a low-sulfur diesel, a Fischer-Tropsch diesel, and three blends: 20 percent Fischer-Tropsch/80 percent low-sulfur diesel; 20 percent biodiesel/80 percent low-sulfur diesel; and 15 percent DMM/85 percent low-sulfur diesel. All six alternative fuel formulations demonstrated benefits by reducing particulate matter (PM) emissions without significant increases in oxides of nitrogen (NOx). The largest decrease in PM emissions was achieved with the 15 percent DMM blend. On average, over the 13 test points, the DMM blend reduced PM emissions by 52 percent in comparison to the baseline diesel fuel.

The paper highlights the use of a light duty axle efficiency test for evaluating the fuel economy performance of automotive gear lubricants. Both final peak axle temperatures and torque efficiencies are recorded for several multigrade automotive gear lubricants. The dependence of temperature on torque efficiencies for the gear lubricants tested are discussed for a variety of driving conditions: city, highway and severe service. Temperature and torque efficiency data show strong dependence on additive system and viscosity- temperature characteristics of the gear lubricants under different driving conditions. A discussion of lubricant rheology and its importance to maintaining film strength for adequate bearing and gear lubrication as related to optimum torque efficiency and axle temperature under varying loads and pinion speeds is also provided.

The Office of Heavy Vehicle Technologies supports research to enable high-efficiency diesel engines to meet future emissions regulations, thus clearing the way for their use in light trucks as well as continuing as the most efficient powerplant for freight-haulers. Compliance with Tier 2 rules and expected heavy duty engine standards will require effective exhaust emission controls (aftertreatment) for diesels in these applications. DOE laboratories are working with industry to improve emission control technologies in projects ranging from application of new diagnostics for elucidating key mechanisms, to development and tests of prototype devices. This paper provides an overview of these R&D efforts, with examples of key findings and developments.

Detroit Diesel Corporation (DDC) is developing the DELTA 4.0L V6 engine, specifically for the North American light truck market. This market poses unique requirements for a diesel engine, necessitating a clean sheet engine design. DELTA was developed from a clean sheet of paper, with the first engine firing just 228 days later. The process began with a Quality Function Deployment (QFD) analysis, which prioritized the development criteria. The development process integrated a co-located, fully cross-functional team. Suppl iers were fully integrated and maintained on-site representation. The first demonstration vehicle moved under its own power 12 weeks after the first engine fired. It was demonstrated to the automotive press 18 days later. DELTA has repeatedly demonstrated its ability to disprove historical North American diesel perceptions and compete directly with gasoline engines. This paper outlines the Generation 0.0 development process and briefly defines the engine.