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During a period from an engine start to activation of a catalytic emission control device, a direct injection spark ignition engine is operated in a stratified stoichiometric charge combustion mode under the control of an engine controller. In the stratified stoichiometric combustion mode, a fuel in

During a period from an engine start to activation of a catalytic emission control device, a direct injection spark ignition engine is operated in a stratified stoichiometric charge combustion mode under the control of an engine controller. In the stratified stoichiometric combustion mode, a fuel injection system carries out a direct cylinder injection on the compression stroke to produce a relatively rich stratified air fuel mixture closely around a spark plug, in a background of a relatively lean air fuel mixture produced homogeneously over the combustion chamber by a direct cylinder injection on the intake stroke or a port or passage injection on or before the intake stroke.

대표청구항 ▼

1. An engine system comprising:a direct injection spark ignition internal combustion engine which comprises a fuel injector for injecting fuel directly into a combustion chamber of the engine, and a spark plug for igniting an air fuel mixture in the combustion chamber; and an engine controller for o

1. An engine system comprising:a direct injection spark ignition internal combustion engine which comprises a fuel injector for injecting fuel directly into a combustion chamber of the engine, and a spark plug for igniting an air fuel mixture in the combustion chamber; and an engine controller for operating the engine in a first stratified charge combustion mode for producing a substantially stoichiometric air fuel mixture concentrated around the spark plug at a time of ignition in a predetermined engine operating region by variably controlling ignition timing and at least one of fuel injection quantity and timing during a compression stroke, for detecting a predetermined request condition requesting a temperature increase of a catalytic emission control device disposed in an exhaust passage of the engine, and for operating the engine in a second stratified charge combustion mode for producing a richer-than-stoichiometric air fuel mixture of a rich air fuel ratio richer than a stoichiometric ratio concentrated around the spark plug at the time of ignition by controlling the fuel injection quantity and fuel injection timing of compression stroke fuel injection on the compression stroke by the fuel injector and the ignition timing of the spark plug when the predetermined request condition is detected, wherein the richer-than-stoichiometric air fuel mixture concentrated around the spark plug at the time of ignition is in an ignitable atomized state with an ignitable air fuel ratio, and wherein the controller sets a fuel atomization interval from a time of a compression stroke fuel injection to the time of ignition longer in the second stratified combustion mode than in the first stratified combustion mode.