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Extensive efforts are being made to improve emissions from 2-stroke diesel engines. These improvements are primarily directed towards older model year engines with relatively high emissions compared with modern diesel engines. While most researchers focus their attention on engine design changes that promise substantial emission improvements, this work dealt with the turbocharger characteristics, especially as related to using internal coatings on both the compressor and turbine housings. Two identical turbochargers were tested on a Detroit Diesel 6V-92TA engine. One of the two turbochargers was left in its production configuration while the other was coated with a clearance control coating on the inside of the compressor and turbine housings. This coating led to a significant reduction in the tip clearance of both the compressor and turbine wheels.

This paper presents the results of an on-road evaluation of in-cylinder ceramic thermal barrier coating GPX″-4M and turbocharger clearance control coating. Engelhard Corporation carried out the testing as a part of a pre-production product development and evaluation process. Contained in the paper are the results of a three-year long experiment conducted on an Engelhard's truck. Discussed in the paper are in-service performance and durability of Engelhard's coating. The experimental fuel usage data underwent substantial statistical treatment and analysis. In combination with the unique test conditions this allowed credible conclusions regarding the truck fuel economy. It was clearly demonstrated that the truck equipped with in-cylinder GPX coated components used 1.4% less fuel than a standard truck for the same amount of work performed over a 16-month period. This fuel saving is associated with the engine rebuild.

The Japan Gas Association has been engaged in the development of a 200-kW-class ceramic natural gas engine system to be used as a co-generation power source, subsidized by Ministry of International Trade and Industry. The engine has several new concepts to achieve high efficiency and low emissions simultaneously and to enable to use natural gas as fuel supplied with low pressure in spite of diesel engine. The co-generation system needs de-NOx system. So, we developed a urea de-NOx catalyst system for high-temperature exhaust gas. This paper will describe the result in the fiscal year 1998.

A light-duty direct-injection diesel engine with dimethyl ether (DME) fuel was studied experimentally. The effects of fuel injection parameters and in-cylinder air motion, such as the pump plunger diameter, nozzle type, fuel injection timing, nozzle tip protrusion, nozzle opening pressure and swirl ratio, on performance and emissions of the DME engine were investigated. Cylinder pressure, needle valve lifts, and emissions were measured after optimization of the fuel-injection and combustion system parameters. By installing a low-pressure pump, a fuel pressure regulator, and a buffer in the fuel supply system, the vapor lock of DME in the fuel system is eliminated. The engine runs smoothly on DME over a wide range of speeds and loads. Thermal efficiency with DME fuel shows 3% higher than that with diesel fuel. The measured injection delay with DME is longer than that with diesel fuel due to the lower acoustic velocity in the liquid DME.

An emissions programme has been undertaken to gain information on the effect of selected fuel parameters on gasoline direct injection (G-DI) vehicle technology(1) with respect to exhaust emissions. Seven fuel parameters, namely aromatic, methyl-tertiary-butyl ether (MTBE), sulphur and olefin content as well as 3 distillation parameters covering the whole boiling range, were independently investigated. It was found that, overall, the fuel effects on regulated (THC, CO, NOx), particulate (Pm), and CO2 emissions were relatively small.

The direct injection gasoline spray-wall interaction was characterized inside a heated pressurized chamber using various visualization techniques, including high-speed laser-sheet macroscopic and microscopic movies up to 25,000 frames per second, shadowgraph, and doublespark particle image velocimetry. Two hollow cone high-pressure swirl injectors having different cone angles were used to inject gasoline onto a heated plate at two different impingement angles. Based on the visualization results, the overall transient spray impingement structure, fuel film formation, and preliminary droplet size and velocity were analyzed. The results show that upward spray vortex inside the spray is more obvious at elevated temperature condition, particularly for the wide-cone-angle injector, due to the vaporization of small droplets and decreased air density. Film build-up on the surface is clearly observed at both ambient and elevated temperature, especially for narrow cone spray.

Two-dimensional Mie and LIEF techniques were applied to investigate the spray propagation, mixture formation and charge distribution at ignition time inside the combustion chamber of a direct injection SI engine. The results obtained provide the propagation of liquid fuel relative to the piston motion and visualize the charge distribution (liquid fuel and fuel vapor) throughout the engine process. Special emphasis was laid on the charge distribution at ignition time for stratified charge operation. By means of a LIEF technique it was possible to measure cyclic fluctuations in the fuel vapor distributions which explain the occurrence of misfiring.

Compared with bathtub combustion chamber which is widely used in SI engines especially in China, this paper introduces an experimental investigation on the performances of SI test engine with a new squish jet-turbulence combustion chamber. The new chamber can combine inlet swirl and squish effectively. Results show that the engine with the new chamber gives better comprehensive performances. The combustion process shortens, and the lean burn limit extends.

In this work a new concept for GDI engines is presented. Concerning a stable ignition a main goal of the so called Bowl-Pre-chamber-Ignition (BPI) process is to reduce the influence of varying flow and spray effects. The characteristic signs of the concept are the dual direct injection, a centrally arranged piston bowl and the special pre-chamber spark plug, that partly dips into the bowl at TDC. During that process most fuel is injected early (intake stroke) into the intake manifold or directly into the cylinder to form a homogeneous pre-mixture. Later in the compression stroke, only a small amount of fuel is injected into the piston bowl. So formed locally stratified charge mixture is transported by the piston bowl to the pre-chamber-spark plug, the pre-chamber dips into the bowl and the mixture flows directly to the spark plug electrode. The result is a very stable lean combustion.

The paper describes detailed studies about the spray formation of a direct-injection high-pressure gasoline injector and the interaction of the droplets with the surrounding compressed air in pressure chamber experiments and inside an optically accessible research engine. Different optical techniques, like stroboscopic video technique, high-speed filming with flood-light illumination or with light-sheet illumination by a copper vapour laser, particle image velocimetry of the droplets, laser-induced fluorescence of the liquid phase, and spontaneous Raman spectroscopy for the measurement of the fuel/air ratio are used. From the recorded images spray characteristics such as spray penetration and spray cone angle are evaluated for different settings of the chamber pressure and temperature and for different rail pressures. The results show that all techniques are suitable to derive the quantities mentioned above.

Our concern was with the phenomenon of the fuel flow rate change in the injector due to deposit formation in the direct injection gasoline engine. The fundamental factors in the deposit formation on the nozzle were investigated, and engine dynamometer tests were performed. It was clarified that the residual fuel in the nozzle hole should be kept in a liquid state so that deposit precursors could be washed away by fuel injections. As a consequence, the nozzle temperature had to be below the 90 vol. % distillation temperature of the fuel, which was the most important index to suppress the deposit formation.

Nissan has developed a practical and available toroidal continuously variable transmission (T-CVT) for passenger vehicles for the first time in the world. This CVT is applicable to engines having an output of torque larger than 400 N-m and makes it possible to use a lock-up clutch at low vehicle speed, resulting in marked improvements in drivability and fuel economy. The authors have developed the T-CVT fluid, which is in this application, having excellent traction coefficient and sufficient capacity as the transmission fluid. This paper mainly describes the traction coefficient measurement procedure and the performance of the newly developed fluid.

New technologies are being commercialized across the automotive industry to address demands for improved fuel economy, emissions reductions, and improved customer satisfaction. Push-belt continuously variable transmissions (b-CVTs) are beginning to command a significant percentage of the market now dominated by manual and conventional automatic transmissions. In addition, automobile manufacturers plan to introduce the first traction drive toroidal-CVTs to the market place within the next five years. A review of the relative benefits and limitations of each of these automatic transmissions exists in the literature. In this paper we consider how the performance requirements of each of these automatic transmission systems impact automatic transmission fluid technology. The physical characteristics and screen test performance of two commercial ATFs, a b-CVTF, and two traction fluids were examined.

Engine operation with spark ignition retarded from MBT timing is used at cold start to reduce HC emissions and increase exhaust gas temperature; however it also results in increased cyclic variations. Steady-state cold fluids testing was performed to better understand the causes of the cycle-to-cycle variations. Detailed analysis of individual cycles was performed to help gain an understanding of the causes of cyclic variations. The important results were: The primary cause of cyclic variations in IMEP is variations in the combustion phasing (location of 50% mass fraction burned). The expansion ratio decreases rapidly during combustion for retarded spark timing and therefore the phasing determines individual cycle thermal efficiency and IMEP. Variations in the late burn have little impact on the IMEP as this combustion occurs close to EVO and does little expansion work.

A recently developed in-cylinder fuel injection probe was used to deposit a small amount of liquid fuel on various surfaces within the combustion chamber of a 4-valve engine that was operating predominately on liquefied petroleum gas (LPG). A fast flame ionization detector (FFID) was used to examine the engine-out emissions of unburned and partially-burned hydrocarbons (HCs). Injector shut-off was used to examine the rate of liquid fuel evaporation. The purpose of these experiments was to provide insights into the HC formation mechanism due to in-cylinder wall wetting. The variables investigated were the effects of engine operating conditions, coolant temperature, in-cylinder wetting location, and the amount of liquid wall wetting. The results of the steady state tests show that in-cylinder wall wetting is an important source of HC emissions both at idle and at a part load, cruise-type condition. The effects of wetting location present the same trend for idle and part load conditions.

The effects of fuel composition and engine operating parameters on high-pressure, direct injection gasoline (DIG) injector plugging and deposit formation have been studied. The engine used was a conventional dual-sparkplug, 2.2-liter Nissan engine modified for direct injection using one of the spark plug holes. The engine was run under 20% rich conditions to accelerate deposit formation. A ten-fuel test matrix was designed around T90, sulfur level, and olefin levels indicated in the European gasoline specifications for year 2000. The gasolines, containing no detergents, were formulated using refinery stream blends to match the specified targets. Injector flow loss was monitored by fuel flow to the engine and monitoring oxygen sensors on each of the four cylinders. The impact of fuel composition on deposit formation and injector plugging is discussed. Injector flow loss was strongly influenced by injector tip temperature.

The stability and dynamic characteristics of frictioninduced vibrations in a simplified aircraft brake model are investigated. A finite element model equipped with nonlinear frictional contact algorithm is used. The constitutive model of the interface is based on an extended version of the Oden-Martins law [1]. The interface material constants are obtained via asperity-based homogenization methodology from the profilometric information on the surface. Initial uncoupled analyses are performed to identify the basic dynamic modes of the model. Frequencies of normal vibrations of the model are found to be dependent on the interface stiffness and the piston pressure. To study the dynamic behavior of the system, its transient response is computed after a perturbation of the steadystate sliding position. It is found that, while the vibrations are subdued in some cases categorized as stable, they grow in other, unstable cases.

The four major discriminators for products in the market place are Technology, Quality,1 Cost and Delivery. Effective measurement systems and initial design quality have the largest impact on delivered field quality, program development cost and timing, as well as customer enthusiasm. System-level reliability testing methods have a major impact on the business health of any product. The implementation of laboratory forced failure testing in simultaneously applied energy environments has the largest influence for "designing in" field reliability and lowering development cost. Clearly a policy change from success based testing to forced failure testing has had the largest impact on results for the consumer.

In an effort to ensure that the characteristics of prototype friction materials do not differ from those of the “same” material when introduced into volume production and that, in production, these characteristics do not vary over time, DaimlerChrysler has instigated the processes of Shoe and Lining Fingerprinting and Production Variation Reduction. For the launch of the 1999 Jeep Grand Cherokee the concept of Production Variation Reduction was extended by the Jeep Platform and BBA Friction, Inc., to 25 pre-production batches of material to eliminate prototype to production variability.

Brake pads with an especially formulated, low-metal organic friction material were tested in a rig especially developed for brake squeal tests. The effect on squeal generation by the addition of 0, 2, 4, 8 and 12 vol% Cu2S to the friction material was investigated. All tests were performed at low speeds, moderate to low brake pressures and with disc temperatures in the range of 70-270 °C. It was found that the addition of Cu 2S consistently reduced the number of generated squeals, with an optimum around 4-8 vol% addition. Further, the addition of Cu2S also lowered the coefficient of friction for the present friction material formulation. A friction minimum was obtained at 8 vol% Cu2S. Included in this investigation were three sets of pads, all containing 8% Cu2S, but with different densities. It was found that the pads with the higher density generated fewer squeals than did the pads with the lower density.