Abstract: An internal combustion engine having a cylinder head body with a pentroof-shaped combustion chamber comprises a piston including a piston cavity and a caldera-shaped protrusion provided around the piston cavity, a fuel injector for injecting fuel downward to the piston cavity and a spark plug disposed obliquely in proximity to an intake valve. The piston cavity is provided on the top surface of the piston being offset on the spark plug side. Further, the caldera-shaped protrusion is slanted towards the spark plug side. Therefore, injected fuel collides against a down-slope of the piston cavity and is diffused partly towards the spark plug and partly towards the cylinder head. As a result, a locally rich air-fuel mixture is formed around the spark plug so as to enable stratified charge combustion.

Abstract: An internal combustion engine having a cylinder head body with a pentroof-shaped combustion chamber comprises a piston including a piston cavity and a circular protrusion provided around the piston cavity, a fuel injector for injecting fuel downward to the piston cavity and a spark plug provided in proximity to an intake valve. Fuel is injected in a shape of a hollow cone and collides against the piston cavity and is diffused The diffused fuel is carried on the tumble flow of intake air and gathers around the electrode of the spark plug, this contributing to securing a stable stratified charge combustion. Further, the configuration of the circular protrusion prevents the sprayed fuel from scattering towards the cylinder wall.