Abstract: Superior piston bowl and combustion chamber configurations are designed for a reverse tumble spark ignition direct injection engine. The piston includes a shallow bowl extending from adjacent an edge of the piston head to an inner side slightly beyond a peak. The bowl features a bowl lip re-entrant angle at the spark plug location having an open or positive re-entrant angle. On lateral edges of the bowl between the inner and outer edges, wing like extensions include negative re-entrant angles. These help contain the injected fuel within the bowl during combustion. Other features of the combustion chamber include vertical intake ports that produce a weak reverse tumbling air flow motion with a tumble ratio of about 0.6, which allows increased flow efficiency of the port. An injector spray cone angle of 90 degrees is preferred with a bowl sized to capture the spray. Various additional features are disclosed.

Abstract: The present invention provides a fuel injector mounted on a side of a combustion chamber and delivers an ovalized fuel spray toward an oblong piston bowl of the chamber. The ovality of the spray is selected in relation to the oblong piston bowl and the motion of the combustion chamber air charge during the piston compression stroke to maintain the fuel charge within the piston bowl volume (including the space above the bowl) during compression and combustion of the fuel charge in the chamber. The shape of the oval spray may be adjusted as desired. In a specific embodiment, the ovality of the fuel spray indicated by the ratio of the major dimension to the minor dimension is in the range of about 2/1 to 4/1 for delivery into an oblong piston bowl with an ovality of about 1.2/1 to 1.5/1.