Internal combustion engine

An internal combustion engine comprising:

• a cylinder head having an inner wall;
• a spark plug arranged at a central portion of the inner wall of said cylinder head;
• a fuel injector arranged on a peripheral portion of the inner wall of said cylinder head;
• a piston having a top face having a depression extending from a point beneath said spark plug to a point beneath a tip portion of said fuel injector, fuel being injected from said fuel injector toward a spherically concaved inner wall of said depression and the spherically concaved inner wall of said depression is symmetrical with respect to a vertical plane including both said spark plug and said fuel injector and has therein a groove extending from a lowermost bottom portion of the spherically concaved inner wall to a position underneath said spark plug along said vertical plane;
• and
• control means for controlling an injection time of said fuel injector in response to an engine load, to inject fuel at a time at which fuel injected by said fuel injector and moving along an axis of injection impinges upon the spherically concaved inner wall of said depression at substantially a right angle when the engine is operating under a heavy load, and to retard the injection time and inject fuel at a time at which said fuel injected by said fuel injector and moving along said axis of injection impinges obliquely upon the spherically concaved inner wall of said depression at an acute angle, to thereby cause an impinged fuel to flow along the spherically concaved inner wall of said depression toward the point beneath said spark plug due to an inertial thereof when the engine is operating under a light load.

An internal combustion engine comprising:

• a cylinder head having an inner wall;
• a spark plug arranged at a central portion of the inner wall of said cylinder head;
• a fuel injector arranged on a peripheral portion of the inner wall of said cylinder head;
• a piston having a top face having a depression extending from a point beneath said spark plug to a point beneath a tip portion of said fuel injector, fuel being injected from said fuel injector toward a concaved inner wall of said depression and the concaved inner wall of said depression having a grooved formed thereon between a lowermost bottom portion of the concaved inner wall of said depression and an upper edge of said depression which is located beneath said spark plug;
• and
• control means for controlling an injection time of said fuel injector in response to an engine load, to inject fuel at a time at which fuel injected by said fuel injector and moving along an axis of injection impinges upon the concaved inner wall of said depression at substantially a right angle when the engine is operating under a heavy load, and to retard the injection time and inject fuel at a time at which said fuel injected by said fuel injector and moving along said axis of injection impinges obliquely upon the concaved inner wall of said depression at an acute angle, to thereby cause an impinged fuel to flow along the concaved inner wall of said depression toward the point beneath said spark plug due to an inertial thereof when the engine is operating under a light load.