In-cylinder injection type spark ignition internal combustion engine

An in-cylinder injection type spark ignition internal combustion engine, comprising:

• a combustion chamber formed between a lower surface of a cylinder head and a top face of a piston inserted in a cylinder, said lower surface of the cylinder head having a first intake opening and a second intake opening and a first exhaust opening and a second exhaust opening, said first and second intake openings being located on one side of and along a plane including an axis of the cylinder and said first and second exhaust openings being located on the other side of and along said plane;
• a fuel injector which directly injects a fuel into said combustion chamber;
• a spark plug provided in said cylinder head such that a portion of the spark plug protrudes into said combustion chamber;
• an intake port having one end that communicates with said first and second intake openings, said intake port extending through said cylinder head toward an upper surface of the cylinder head;
• an exhaust port having one end that communicates with said first and second exhaust openings, said exhaust port extending through said cylinder head toward a side face of the cylinder head;
• a first intake valve including a valve body that opens and closes said first intake opening, and a shaft portion formed integrally with the valve body, said first intake valve being placed in a selected one of a first position in which the intake port is held in communication with the combustion chamber such that intake air is allowed to flow into the combustion chamber, and a second position in which the intake port is shut off from the combustion chamber such that the intake air is inhibited from flowing into the combustion chamber;
• a second intake valve including a valve body that opens and closes said second intake opening, and a shaft portion formed integrally with the valve body, said second intake valve being placed in a selected one of the first and second positions;
• a first exhaust valve including a valve body that opens and closes said first exhaust opening, and a shaft portion formed integrally with the valve body, said first exhaust valve being located in a substantially symmetrical relationship with said first intake valve with respect to said plane, said first exhaust valve being placed in a selected one of a third position in which the exhaust port is held in communication with the combustion chamber such that an exhaust gas is allowed to be discharged from the combustion chamber, and a fourth position in which the exhaust port is shut off from the combustion chamber such that the exhaust gas is inhibited from being discharged from the combustion chamber;
• a second exhaust valve including a valve body that opens and closes said second exhaust opening, and a shaft portion formed integrally with the valve body, said second exhaust valve being located in a substantially symmetrical relationship with said second intake valve with respect to said plane, said second exhaust valve being placed in a selected one of the third and fourth positions;
• and
• a single camshaft including a plurality of cam portions which respectively drive said first and second intake valves and said first and second exhaust valves to open and close the first and second intake valves and the first and second exhaust valves, said camshaft being supported by said cylinder head and extending substantially in parallel with said plane,
• wherein the intake port extends in a direction substantially perpendicular to at least one of a first shortest line connecting the distal end of a shaft portion of said first intake valve and the distal end of a shaft portion of said first exhaust valve, and a second shortest line connecting the distal end of a shaft portion of said second intake valve and the distal end of a shaft portion of said second exhaust valve.

An in-cylinder injection type spark ignition internal combustion engine, comprising:

• a combustion chamber defined by a lower surface of a cylinder head and an upper surface of a piston provided within a cylinder;
• an intake port, a first end of said intake port being in communication with said combustion chamber through an intake opening provided at one side of a plane including a longitudinal axis of the cylinder, and a second end of said intake port being open at an upper surface of said cylinder head;
• an intake valve for opening and closing said intake opening, said intake valve being provided at an angle with respect to the longitudinal axis of the cylinder such that a shaft portion of said intake valve extends away from the longitudinal axis of the cylinder within said one side of the plane;
• an exhaust port communicating with said combustion chamber through an exhaust opening provided at the other side of the plane;
• an exhaust valve for opening and closing said exhaust opening, said exhaust valve being provided at an angle with respect to the longitudinal axis of the cylinder such that a shaft portion of said exhaust valve extends away from the longitudinal axis of the cylinder within the other side of the plane;
• and
• a single cam shaft supported by the cylinder head within a region defined by shaft portions of said intake valve and said exhaust valve,
• wherein said intake port extends within one of a region between the shaft portion of said intake valve and said single cam shaft, and a region between the shaft portion of said exhaust valve and said single cam shaft.