Combustion process for engine of spark ignition, fuel injection type

Claim 2

A combustion process for operating an internal combustion engine of the spark ignition, fuel injection type during idle speed and part throttle conditions of operation, including the steps of, inducting a charge of essentially fresh air into each of the engine cylinders with a motion promoting mixing with fuel to be subsequently injected thereinto, injecting fuel into each of said cylinders late in the compression cycle so as to provide a localized overrich mixture in the combustion zone at the time of ignition thereby reducing the formation of oxides of nitrogen and an overall lean mixture in the cylinder, and progressively throttling the intake of said air into said cylinders and decreasing fuel flow thereinto upon decrease in load in a manner to progressively increase the air/fuel ratio from a near stoichiometric value until a predetermined value substantially greater than stoichiometric is reached whereby the said predetermined value substantially leaner than stoichiometric air/fuel ratio is thereafter maintained to provide total combustion within a predetermined period while minimizing residual quantities of unburned hydrocarbons and other undesirable elements in the combustion products.

Claim 3

A combustion process as in claim 1, including recirculating a portion of the exhaust gases into the engine cylinders during part throttle operations to reduce the formation of oxides of nitrogen by reducing availability of oxygen anD thereby reducing peak combustion chamber temperatures.

Claim 4

A combustion process for operating an internal combustion engine of the spark ignition, fuel injection type over the entire load range of said engine comprising the steps of, inducting an unthrottled charge of essentially fresh air into each of the engine cylinders during wide open throttle full load conditions of engine operation, injecting fuel into each of said cylinders in a manner providing an overall slightly richer than stoichiometric air/fuel mixture in the cylinders upon mixing therebetween for a maximum output of said engine, igniting said charge, decreasing the fuel supply to said cylinders as a function of the decrease in engine load without throttling the intake of air thereinto so that the overall air/fuel ratio in said cylinder leans as engine load decreases, continuing the leaning until a minimum desirable air/fuel ratio lower limit substantially leaner than stoichiometric is reached, and subsequently continuing to inject fuel into each cylinder late in the compression cycle whereby a localized overrich mixture exists in the combustion zone at ignition thereby reducing the formation of oxides of nitrogen while progressively throttling the air intake into said cylinders in proportion to the decrease in load on said engine in a manner to maintain essentially constant the substantially leaner than stoichiometric overall air/fuel ratio in said cylinders the latter being lean enough to minimize the existence of unburned hydrocarbons and other undesirable combustion products and yet sufficiently combustible to complete total combustion within a predetermined time providing optimum efficient engine operation.

Claim 5

A combustion process for operating an internal combustion engine of the spark ignition, fuel injection type over the entire load range of said engine comprising the steps of, inducting an unthrottled charge of essentially fresh air into each of the engine cylinders during wide open throttle full load conditions of engine operation, injecting fuel into each of said cylinders in a manner providing an overall slightly richer than stoichiometric air/fuel mixture in the cylinders upon mixing therebetween for a maximum output of said engine, igniting said charge, decreasing the fuel supply to said cylinders as a function of the decrease in engine load without throttling the intake of air thereinto so that the overall air/fuel ratio in said cylinder leans as engine load decreases, continuing the leaning until a minimum desirable air/fuel ratio lower limit substantially leaner than stoichiometric is reached, and subsequently continuing to inject fuel into each cylinder late in the compression cycle whereby a localized overrich mixture exists in the combustion zone at ignition thereby reducing the formation of oxides of nitrogen while progressively throttling the air intake into said cylinders in proportion to the decrease in load on said engine in a manner to maintain essentially constant the substantially leaner than stoichiometric overall air/fuel ratio in said cylinders the latter being lean enough to minimize the existence of unburned hydrocarbons and other undesirable combustion products and yet sufficiently combustible to complete total combustion within a predetermined time providing optimum efficient engine operation.

Claim 6

A combustion process as in claim 3, including recirculating exhaust gases into the engine cylinders during part throttle operations to reduce the formation of oxides of nitrogen by reducing peak combustion temperatures.