NATURAL-INTAKE INTERNAL COMBUSTION ENGINE FOR VEHICLE

摘要

PROBLEM TO BE SOLVED: To further improve a fuel consumption rate, increase the productivity of an internal combustion engine with a simple structure, and also suppress the increases of the cost and weight of the internal combustion engine by operating with a mirror cycle in the entire operating range including a high load and high speed area in the natural-intake internal combustion engine for vehicle having an operating range including from a no-load area to a high load and high speed area. SOLUTION: This natural-intake internal combustion engine E for vehicle comprises a cylinder 2 for reciprocally fitting a piston 8 thereto and an intake valve 35 and an exhaust valve 36 opened and closed at specified opening and closing timings in all operating ranges including the no-load range to a high load and high speed range. The valve closing timing of the intake valve 35 is set to a specified valve closing timing before a bottom dead center or after a bottom dead center where the intake in the cylinder 2 flows reversely to the upstream of the intake valve 35, and the displacement of the internal combustion engine E is set to a specified displacement capable of providing the maximum required illustrated output of the internal combustion engine E by such an operation that the intake valve 35 is closed at the specified valve closing timing in the high load and high speed range.