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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.