Apparatus for and method of controlling internal combustion engine

A method of controlling a spark-ignition internal combustion engine, comprising the steps of:

• injecting fuel directly into a combustion chamber of the spark-ignition engine using a fuel injection means;
• igniting, in a vicinity of said fuel injection means, a fuel-air mixture in said combustion chamber using an ignition means;
• detecting an output torque of the spark-ignition engine using a torque detection means;
• introducing intake air into said combustion chamber using a valve means;
• controlling an amount of the fuel to be injected from said fuel injection means, and a timing of the injection of the fuel, using a fuel control means;
• controlling an ignition timing of said ignition means using an ignition timing control means;
• controlling an amount of the intake air into said combustion chamber using an intake air amount control means;
• in order that a value of the output torque detected by said torque detection means can approach a predetermined value, using said fuel control means to change the fuel amount and using said intake air amount control means to change the intake air amount to thereby change an air/fuel ratio in said combustion chamber in such a manner so that said value approaches said predetermined value;
• when fuel consumption is under a partial load, igniting the air-fuel mixture after the fuel is injected into said combustion chamber as a spray, to thereby cause a resulting flame to spread into a cylinder of the engine to effect combustion therein;
• and
• when a fuel consumption load is increased to a point where soot is produced in a stratified combustion, injecting the fuel into the combustion chamber a plurality of times in a divided manner to produce a premixture within the cylinder by a front-half injection that is burned when a flame, produced by a latter-half injection, is jetted into the cylinder.

A method for controlling a spark-ignition internal combustion engine, said engine including a fuel injection means for injection fuel directly into a combustion chamber of the engine, an ignition means, located in a vicinity of said fuel injection means, for igniting a fuel/air mixture in said combustion chamber, a torque detection means for detecting an output torque of the engine, a valve means for introducing air into said combustion chamber, and a control means for controlling an amount of the fuel to be injected into said combustion chamber, an amount of the air to be introduced into said combustion chamber, timing of fuel injection into said combustion chamber, and timing of ignition of said air/fuel mixture in said combustion chamber, said method comprising the steps of:

• controlling the relative amounts of fuel and air passing into said combustion chamber to change an air/fuel ratio in said combustion chamber to such a degree that a value of the output torque of the engine approaches a predetermined value;
• igniting the air/fuel mixture at a predetermined time after said fuel is injected as a spray into said combustion chamber to produce a flame which spreads into a cylinder of the engine for effecting combustion therein;
• and
• injecting the fuel into the combustion chamber a plurality of times in a divided manner, when a fuel consumption load increases to such a degree that soot is produced in a stratified combustion, so as to produce a premixture within said cylinder by a front-half injection that is burned when a flame, produced by a latter-half injection, is jetted into the cylinder.

A spark-ignition internal combustion engine comprising:

• a cylinder having therein a combustion chamber defined by a cylindrical portion and a vertically-movable piston;
• a fuel injection means for injecting fuel directly into said combustion chamber;
• ignition means for igniting a mixture of air and fuel in said combustion chamber;
• ignition timing control means for controlling an ignition timing of said ignition means, said ignition means being provided at an inner peripheral wall surface of said cylindrical portion of said combustion chamber;
• and
• fuel injection control means for causing said fuel injection means to inject fuel into said combustion chamber as a late injection during a stroke of the cylinder which corresponds to a time approaching said ignition timing, wherein said fuel is injected into said combustion chamber in such a manner as to cause the air/fuel mixture in said chamber to become stratified, and to thereby form a fuel-rich mixture in a central region of said chamber and a fuel-lean mixture at a peripheral region of said chamber.