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Sector mesh modeling is the dominant computational approach for combustion system design optimization. The aim of this work is to quantify the errors descending from the sector mesh approach through three geometric modeling approaches to an optical diesel engine. A full engine geometry mesh is created, including valves and intake and exhaust ports and runners, and a full-cycle flow simulation is performed until fired TDC. Next, an axisymmetric sector cylinder mesh is initialized with homogeneous bulk in-cylinder initial conditions initialized from the full-cycle simulation. Finally, a 360-degree azimuthal mesh of the cylinder is initialized with flow and thermodynamics fields at IVC mapped from the full engine geometry using a conservative interpolation approach. A study of the in-cylinder flow features until TDC showed that the geometric features on the cylinder head (valve tilt and protrusion into the combustion chamber, valve recesses) have a large impact on flow complexity.

Two combustion systems were developed and optimized for an engine for a power cylinder of 0.8-0.9L/cylinder. The first design was a re-entrant bowl concept which was based on the combustion system of a smaller engine with roughly 0.5L/cylinder. The second design was a chamfered bowl concept, a variant of a reentrant bowl that deliberately splits fuel between the bowl and the squish region. For each combustion system concept, nozzle tip protrusion, swirl, and nozzle configuration (number of holes, nozzle flow, and spray angle) were optimized. Several similarities between combustion system concepts were noted, including the optimal swirl and number of holes. The resulting optimums for each concept were compared. The chamfered combustion system was found to have better part-load emissions and fuel consumption tradeoffs. Full load performance was similar at low speed between the two combustion systems, but the reentrant combustion system had advantages at high engine speed and load.

A new, 1-D analytical engine thermal management tool was developed to model piston, oil and coolant temperatures in the Ford 3.5L engine family. The model includes: a detailed lubrication system, including piston oil-squirters, which accurately represents oil flow rates, pressure drops and component heat transfer rates under non-isothermal conditions; a detailed coolant system, which accurately represents coolant flow rates, pressure drops and component heat transfer rates; a turbocharger model, which includes thermal interactions with coolant, oil, intake air and exhaust gases (modeled as air), and heat transfer to the surroundings; and lumped thermal models for engine components such as block, heads, pistons, turbochargers, oil cooler and cooling tower. The model was preliminarily calibrated for the 3.5L EcoBoost™ engine, across the speed range from 1500 to 5500 rpm, using wide-open-throttle data taken from an early heat rejection study.

A test cell was developed for evaluating a 6-speed automatic transmission. The target vehicle had an internal combustion 5.4L gasoline V8 engine. An electric dynamometer was used to closely simulate the engine characteristics. This included generating mean torque from the ECU engine map, with a transient capability of 10,000 rpm/second. Engine inertia was simulated with a transient capability of 20,000 rpm/second, and torque pulsation was simulated individually for each piston, with a transient capability of 50,000 rpm/second. Quantitative results are presented for the correlation between the engine driven and the dynamometer driven transmission performance over more than 60 test cycles. Concerns about using the virtual engine in validation testing are discussed, and related to the high frequency transient performance required from the electric dynamometer. Qualitative differences between the fueled engine and electric driven testing are presented.

Piston slap is a problem that plagues many engines. One of the most difficult aspects of designing to eliminate piston slap is that slight differences in operating conditions and in part geometries from build to build can create large differences in the magnitude of piston slap. In this paper we will describe a design for robustness CAE approach to eliminating piston slap. This approach considers the variations of the significant control factors in the design, e.g. piston pin offset, piston skirt design, etc. as well as the variation in the noise factors the system is subjected to, e.g. assembly clearance, skirt collapse, peak cylinder pressure, cylinder pressure rise rate, and location of peak cylinder pressure. Using analytical knowledge about how these various factors impact the generation of piston slap, a piston design for low levels of piston slap can be determined that is robust to the various noise factors.

Engine excitation forces have been studied in the past using one of two methods; a lumped sum or a totally distributed approach. The lumped sum approach gives the well-understood engine inherent unbalance and the totally distributed approach is used in engine CAE models to determine the overall engine response. The approach that will be described in this paper identifies an intermediate level of sophistication. The methodology implemented considers single cylinder forces on the engine block, piston side thrust and main bearing forces, and decomposes them into their order content. The forces are then phased and geometrically distributed appropriately for each cylinder and then each order is analyzed relative to know distributions that are NVH concerns, V-block breathing, block side wall breathing, and block lateral and vertical bending.

Combustion flame geometry calculation is a critical task in the design and analysis of combustion engine chamber. Combustion flame directly influences the fuel economy, engine performance and efficiency. Currently, many of the flame geometry calculation methods assume certain specific chamber and piston top shapes and make some approximations to them. Even further, most methods can not handle multiple spark plug set-ups. Consequently, most of the current flame geometry calculation methods do not give accurate results and have some built-in limitations. They are particularly poor for adapting to any kind of new chamber geometry and spark plug set-up design. This report presents a novel methodology which allows the accurate calculation of flame geometry regardless of the chamber geometry and the number of spark plugs. In this methodology, solid models are used to represent the components within the chamber and unique attributes (colors) are attached respectively to these components.

Spark knock pressure oscillations can be detected by a cylinder pressure transducer or by an accelerometer mounted on the engine block. Accelerometer-based detection is lower cost but is affected by extraneous mechanical vibrations and the frequency response of the engine block and accelerometer. The knock oscillation frequency changes during the expansion stroke because the chamber geometry is changing due to the piston motion and the burned gases are cooling. Spectrogram analysis shows the time-dependent frequency content of the pressure and acceleration signals, revealing characteristic signatures of knock and mechanical vibrations. Illustrative spectrograms are presented which yield physical insight into accelerometer-based knock detection.

Torque converter clutch friction interface and automatic transmission fluid (ATF) temperatures, pressure difference across the clutch piston, flow through the friction material grooves, and engine crankshaft dynamic torque were measured for typical operating conditions on a running transmission. The friction coefficient, clutch unit pressure, fraction of heat rejected to ATF flowing through the grooves, and time dependent thermal response were determined. Simplified heat transfer calculations were compared with thermal data. Clutch interface temperatures were assessed as they relate to the process of friction material and ATF degradation. The inductively powered radiotelemetry system was found to be a robust and powerful tool for investigating continuously slipping clutch system performance.

Application process, and performance in engine dynamometer and high mileage vehicle fleet durability tests of Plasmaspray coated bore aluminum block engines are discussed. Fuel economy, oil consumption, power and wear data for Ford 4.6L-V8 aluminum block engines utilizing very low cost iron/iron oxide base coatings, and stainless steel/BN solid film lubricant Plasmasprayed coatings are presented. Test results from Ford's 100 hour Piston & Gasket Engine Dynamometer Durability Tests, and Fleet Vehicle Durability Tests show ring/bore wear reductions of more than 40% relative to production cast iron bore systems with Oil Economy averaging more than 13,600 km/l (8000 mi/qt).

An investigation describing engine friction reduction benefits attainable via the introduction of Solid Film Lubricants to piston skirts is presented. Ford II-25 thermoset and II-25 waterborne molybdenum disulfide based solid film lubricants were shown through single cylinder motored engine experiments, to produce piston system friction reductions of 12 to 17% at 1500 rpm. Further tests undertaken in fired engine dynamometer studies, on a 1.91 1-4 CVH engine, demonstrated total engine friction reductions of 6% at W.O.T. conditions. The reduced engine friction resulted in lowering BSFC at 850 rpm by 3 to 4%. Tests conducted by Powertrain Operations confirmed durability. II-25 thermoset was selected for production implementation on all new Ford engines starting from model year 1995.

A process for creating a Customer Correlated, Accelerated, Life Test is presented. This process, which results in a model for predicting reliability, has been applied to a cold weather piston scuff problem. In this paper, the authors will discuss development of frequency distributions for customer environmental and operational use, establishment of customer based failure criteria, development of an accelerated test based on degradation, selection of testing strategies, data analyses, and measurement techniques.

A single-cylinder, two-valve engine was operated with independent cooling circuits for the engine block and cylinder head to investigate the effect of temperature distribution on HC emissions. The goal was to understand and quantify the mechanisms responsible for decreased HC emissions at elevated temperatures. Tests were run at a typical road load condition using two different fuels (a 97 RON blend and isopentane - to eliminate liquid fuel and oil layer absorption effects). The total HC emissions (97 RON fuel) decreased by 15-20% with an increase in either the cylinder head or engine block coolant temperature from 71 to 110 °C. When operating with isopentane the HC emissions decreased by 15-20% with an increase in the engine block temperature from 71 to 110 °C but were essentially unaffected by cylinder head temperature. This indicates that the cylinder head temperature primarily influenced the HC emissions from liquid fuel effects.

Friction and scuffing resistance characteristics of two piston alloy materials have been investigated by using a long-stroke reciprocating test rig. Tests were conducted under the same load, speed, and starved changing to dry lubrication conditions until the scuffing failure occurred, as indicated by a sudden change of the frictional force signal which was monitored continuously. Measured friction coefficient and scuffing threshold and life results were obtained, and the piston alloy with the better scuffing resistance capability has been identified. Surface texture of new and scuffed piston and cylinder bore specimen surfaces have been measured and characterized by a combination of amplitude and spacing parameters.

A model is presented which incorporates the key mechanisms in the formation and reduction of unburned HC emissions from spark ignited engines. The model includes the effects of piston crevice volume, oil layer absorption / desorption, partial burns, and in-cylinder and exhaust port oxidation. The mechanism for the filling and emptying of the piston crevice takes into account the location of the flame front so that the flow of both burned gas and unburned gas is recognized. Oxidation of unburned fuel is calculated with a global, Arrhenius-type equation. A newly developed submodel is included which calculates the amount of unburned fuel to be added to the cylinder as a result of partial burns. At each crankangle, the submodel compares the rate of change of the burned gas volume to the rate of change of the cylinder volume.

Rheological measurements were performed on a series of lubricants for flexible fuel vehicles, and blends of water or methanol in these oils. A series of measurements, including kinematic viscosity, viscosity at low and high shear rates, low shear viscosity under borderline pumping conditions, and density were performed on all oils and blends. The effects of mixing conditions, such as mixing speed and temperature on these properties were also studied. Viscosity increases when water emulsifies in oils. Methanol exhibits limited solubility in all oils, but more so in synthetic base oils. Viscosity tests at 248 K (-25°C) do not indicate the onset of critical pumping conditions, even at high concentrations of water or methanol. Tests at high shear rates at 323 K (50°C) suggest that water-oil emulsions are quite stable, while methanol-oil blends lose their methanol content either due to evaporation or shear-induced separation.

A structural ceramic diesel engine has the potential to provide low heat rejection and significant improvements in fuel economy. Analytical and experimental evaluations were conducted on the critical elements of this engine. The structural ceramic components, which included the cylinder, piston and pin, operated successfully in a single cylinder engine for over 100 hours. The potential for up to 8-11% improvement in indicated specific fuel consumption was projected when corrections for blow-by were applied. The ringless piston with gas squeeze film lubrication avoided the difficulty with liquid lubricants in the high temperature piston/cylinder area. The resulting reduction in friction was projected to provide an additional 15% improvement in brake specific fuel consumption for a multi-cylinder engine at light loads.

This paper presents the design and operation of a new stepped bore master cylinder (fast-fill) which also integrates the rear brake proportioning valves and brake failure warning device in one major assembly. This design optimizes weight, performance and package together with several unique design features. It incorporates a combination of a plastic reservoir, permanent mold aluminum body, steel pistons, and minaturized steel proportioning valves resulting in a significant weight and cost reduction versus equivalent hydraulic actuation systems.

A method for the measurement of nitric oxide (NO) in photochemical smog research was developed using the chemiluminescence from the rapid reaction between ozone (O3) and NO. An instrument based on this method has been constructed; it is applicable to a number of automotive problems. This NO detector has been tested extensively in both laboratory and dynamometer experiments, and has been shown to have several outstanding features: detection sensitivity of 0.01-5000 ppm, selective detection for NO, continuous monitoring with fast response time, and good stability and ease of operation. Examples of results obtained in turbine experiments and in vehicle exhaust analysis are presented.