US 5,642,705 A · Control system and method for direct fuel injection engine

Abstract

In a catalyst activation control system for a direct fuel injection engine for igniting primary fuel injected into each cylinder, an additional fuel is injected at least once into each cylinder from an early period to a middle period of an expansion stroke of the primary fuel combustion in accordance with the engine operating conditions, to fire the additional injection fuel by flame propagation of the preceding fuel combustion (without re-ignition) for eliminating misfire, so that an exhaust gas temperature can be raised stably to activate catalyst for purification of exhaust gas. Further, any one of the additional fuel injection method and an ignition timing retarding method can be appropriately selected in accordance with the engine operating conditions for economization of fuel. Further, whenever a quantity of heat generated by the primary fuel combustion is not large enough to fire the additional injection fuel, any one of a method of changing a stratification combustion to a uniform combustion, a method of increasing the first fuel injection amount, and a method of interrupting the additional fuel injection can be selected appropriately for protectiing the catalyst.

Claims41

Dependent claims

A method of activating a catalyst for a direct fuel injection engine, comprising the steps of:

detecting engine operating parameters;
calculating a basic fuel injection amount on the basis of the detected engine operating conditions;
checking whether n-time fuel injection is needed or not;
setting a first fuel injection amount by correcting the basic fuel injection amount on the basis of various engine operating conditions and further setting a first fuel injection timing when n-time fuel injection is not needed;
and
setting a first fuel injection amount, a second fuel injection amount, a third fuel injection amount, in sequence when n-time fuel injection is needed;
and further setting a first injection timing, a second fuel injection timing, a third fuel injection timing in sequence.

4 more elements

A catalyst activation control system for a direct fuel injection into a spark ignition multicylinder engine having a catalyst disposed in an engine exhaust system for said engine, said injection being into a combustion chamber of each cylinder for selectively performing a stratification combustion and uniform combustion, comprising:

engine operating condition detecting means for detecting various engine operating conditions;
primary fuel combustion means for performing a primary combustion by spark-igniting a primary fuel directly injected through an injector into each cylinder depending on said engine operating conditions;
and
catalyst activating means for injecting a subsidiary fuel into each cylinder during the expansion stroke of the primary fuel combustion so as to fire the subsidiary injection fuel by flame propagation of the primary fuel combustion without spark-igniting whereby an exhaust gas temperature can be raised for catalyst activation.

1 more element

Dependencies are inferred from the claim text.

Control system and method for direct fuel injection engine

Life of this patent

Control system and method for direct fuel injection engine

Life of this patent

Abstract

Claims41