Direct fuel injection engine

A method of operating a direct fuel injection internal combustion engine comprising:

• reciprocating a piston in a cylinder, including a top surface having a first outer cavity having a first cavity center axis, and a second inner cavity located entirely in the outer cavity in a top plan view and having a second cavity center axis offset from the cylinder;
• selectively injecting a fuel stream directly into the combustion chamber towards the outer and inner cavities in the top surface of the piston such that the fuel stream has an injection center axis that is slanted relative to the cylinder center axis;
• and
• igniting a stratified fuel-air mixture formed above at least one of the inner and outer cavities.

A direct fuel injection engine comprising:

• a combustion chamber;
• a piston disposed in the combustion chamber to move along a cylinder center axis, the piston including a top surface having a first outer cavity having a first cavity center axis, and a second inner cavity located in the outer cavity and having a second cavity center axis offset from the cylinder center axis of the piston in a direction perpendicular to the cylinder center axis;
• a spark plug having a tip arranged in an upper area of the combustion chamber to ignite a fuel-air mixture inside the combustion chamber;
• and
• a fuel injection valve arranged in the upper area of the combustion chamber to inject a fuel stream directly into the combustion chamber towards the outer and inner cavities in the top surface of the piston, the fuel stream having an injection center axis that is slanted relative to the cylinder center axis,
• the first and second center cavity axes of the outer and inner cavities being offset from the cylinder center axis toward where the injection center axis of the fuel stream injected from the fuel injection valve at a time of fuel injection, and
• the fuel injection valve including a fuel injection point being arranged closer to the second cavity center axis of the inner cavity than to the first cavity center axis of the outer cavity as measured perpendicular to the first and second center cavity axes of the outer and inner cavities.

A direct fuel injection engine comprising:

• a combustion chamber:
• a piston disposed in the combustion chamber to move along a cylinder center axis, the piston including a top surface having a first outer cavity having a first cavity center axis, and a second inner cavity located in the outer cavity and having a second cavity center axis offset from the cylinder center axis of the piston in a direction perpendicular to the cylinder center axis;
• a spark plug having a tip arranged in an upper area of the combustion chamber to ignite a fuel-air mixture inside the combustion chamber;
• and
• a fuel injection valve arranged in the upper area of the combustion chamber to inject a fuel stream directly into the combustion chamber towards the outer and inner cavities in the top surface of the piston, the fuel stream having an injection center axis that is slanted relative to the cylinder center axis,
• the outer cavity being generally circular in a top plan view with the first cavity center axis positioned approximately on the cylinder center axis, and
• the inner cavity being generally circular in a top plan view with the second cavity center axis positioned in a different location than the first cavity center axis.