Search Results

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.

The ceramic insert concept far an uncooled, DI diesel engine was evaluated. Small improvements in fuel consumption were projected for this engine relative to a ceramic coated engine. A PSZ cylinder head plate, lip insert in the piston and above-the-rings cylinder liner operated successfully for short term tests after finite element analyses, Weibull failure analyses and iterative testing and design modifications. Heat loss was reduced 25% and the fuel consumption was improved 5 to 9% relative to a water-cooled engine. The combustion analysis parameters indicated that the ceramic insert engine provided higher in-cylinder temperatures relative to the ceramic coated engine.

Advanced techniques for regenerating diesel particulate traps are described. A bypassable trap system minimized regeneration thermal energy requirements. Thermal regeneration systems with burners or electric resistance heaters were evaluated. Regeneration emissions and fuel consumption penalties were measured. Catalytic fuel additives consisting of octoate based compounds of copper and nickel, and copper and cerium provided reductions of up to 410°F in trap regeneration temperature. Durability tests confirmed frequent self regeneration with fuel additives. Over 95% of the fuel additive was collected by the trap. The useful life of the trap having a volume equal to engine displacement was estimated to be 30,000 miles.

Capabilities of DI diesel engines for passenger cars were evaluated in a research program. Three experimental DI diesel engines, a naturally aspirated 2.4L four cylinder engine and a naturally aspirated and turbocharged 1.3L three cylinder engine, were designed, built and developed. Design parameters and calibrations were determined for optimized power and fuel economy at low emission levels. The effects of cylinder displacement and turbocharging were evaluated. Vehicle tests showed that the DI diesel engine provided an 11 to 13% improvement in fuel economy relative to the IDI diesel engine. The low mileage objectives assumed for the 1985 Federal emission standards were met at vehicle test weights up to 3125 lbs.

Thermal and catalytic techniques for regenerating particulate traps were assessed. The thermal technique used a burner which heated engine exhaust to the ignition temperature of the particulates to achieve over 90% regeneration effectiveness. HC, CO and particulate emissions resulting from combustion of particulates and burner exhaust were 25 to 50% of the allowable vehicle emissions for one CVS cycle. The fuel consumed by the burner was 9% of the fuel consumed by a vehicle over one CVS cycle. Problems with burner nozzle clogging, ignition reliability, trap durability and control system requirements were identified. In the catalytic technique, Diesel fuel containing .5 gm/gal lead and .25 gm/gal copper lowered the ignition temperature of the particulates by 425°F so that periodic regeneration occurred. The trap collected nearly all of the lead and copper resulting in limited trap life, and deposits on the engine fuel nozzles tended to increase HC emissions.

The effects of current mechanical fuel control systems on CVS emissions and maximum fueling rate smoke levels of light-duty Diesel engines were investigated. A comparison of emission projections made from steady state mapping data and actual vehicle emission test results indicated that modifications to the transient fueling characteristics had the potential to reduce particulate emissions by over 20%. An experimental Diesel electronic fuel control system was developed and used to assess the effects of fuel control system modifications on Diesel vehicle emissions and smoke levels. Modified governor characteristics were shown to provide a 37% reduction in particulate emissions relative to the baseline min-max governor. Maximum fueling rate calibrations were developed to provide constant smoke levels across the engine speed range.

Diesel engine particulates collected on a trap cause the exhaust back pressure to increase and adversely affect fuel economy and vehicle performance. Therefore, a trap must be periodically regenerated by oxidizing the collected particulates. Several techniques for regenerating a Diesel particulate trap are discussed. Regeneration was achieved with high speed and high load engine operation. Lead, added to the Diesel fuel, acted as a catalyst and reduced the ignition temperature of particulates collected on a trap by about 300°F. Throttling the intake air flow increased exhaust temperature to facilitate regeneration at moderate vehicle speeds. An externally fueled burner provided regeneration over the widest range of engine operating conditions, including idle.

The emission control potential of typical divided chamber, light-duty Diesel engines was investigated by using engine dynamometer mapping tests, vehicle tests with engines modified to implement selected control strategies for reduced emission levels, experiments with combustion system modifications, and evaluations of techniques for the exhaust treatment of particulate emissions. A dynamometer mapping program was conducted on a Diesel engine with a swirl chamber combustion system to determine the emission control capability with modulated EGR and fuel injection timing. Emission projections from mapping tests, confirmed by selected vehicle test results, indicated that the low mileage engineering objectives assumed for the .41/3.4/1.0/.6 gm/mi HC/CO/NOx/particulate emission level may be approached in experimental laboratory vehicles up to 3000 lb. inertia weight with optimized control systems.

Engine-fuel relationships of the Ford PROCO stratified charge engine have been examined. The test program was conducted in three phases to assess the interrelationships between exhaust emissions, fuel economy, octane requirement, and fuel properties in an experimental, research, single cylinder, stratified charge PROCO (programmed combustion) engine. In Phase I, tests were conducted at a steady-state speed-load condition to determine the effect of engine calibration parameters on emissions and fuel economy after an initial evaluation of engine operation with three different ignition system configurations. A dual ignition system produced reliable, misfire-free operation with the dilute mixtures and high EGR rates tested. In Phase II, five fuels with significantly different volatility properties and composition were tested to determine their effect on emissions and fuel economy of the PROCO engine.

The Ford PROCO stratified charge engine combines the desirable characteristics of premixed charge and Diesel engines. The outstanding characteristics of premixed charge engines are their high specific output, wide speed range, light weight and easy startability but they exhibit only modest fuel economy and relatively high exhaust emissions. The desirable characteristic of the Diesel engine is its outstanding fuel economy. However, the disadvantages of the Diesel, which include noisy operation, limited speed range, exhaust odor, smoke, hard startability, and particulate emissions have tended to limit their acceptance. In the gasoline fueled, PROCO stratified charge engine, direct cylinder fuel injection permits operation at overall lean mixture ratios and higher compression ratio. These features enable the PROCO engine to achieve brake specific fuel consumption values in the range of prechamber diesel engines.

The intent of this paper is to put into proper perspective the relationships among the vehicle, the thermodynamic cycle, and the combustion process as they relate to exhaust emissions from a gas turbine-powered passenger car. The influence of such factors as car size, installed power, regeneration, and other cycle variables on level road load fuel economy, and on the production of oxides of nitrogen and carbon monoxide, are examined. In limited checks against experimental data, the mathematical model of the combustor used in this study has proved to be a reliable indicator of emission trends. The calculated emission levels are not final, however, with deficiencies subject to improvement as new combustor concepts are developed.

Two steam-powered passenger ears have been designed, built, and tested. The SE-101 is an intermediate sport coupe incorporating the comfort and convenience features of a modern passenger car and vehicle performance comparable to a low-powered automobile. The SE-124 is a very low-power intermediate sedan with manual start and semiautomatic control. The characteristics of these cars were evaluated relative to the operational requirements of current transportation needs, with particular emphasis on exhaust emissions. Start-up time, exhaust emissions, fuel economy, acceleration, and water consumption data are presented. Although any one of these characteristics may be improved at the expense of others, it does not appear that any compromise can satisfy all of the areas required by today's motorist.