The present invention relates in general to two-stroke-per-cycle, direct-fuel-oil-injected IC internal combustion (IC) engines — and to a new thermodynamic cycle of operation for these types of engines that provides, among other things, higher efficiency, more complete combustion, less fuel consumption, almost no harmful or hazardous emissions, and greater mechanical simplicity than prior art IC engines. We believe this is the best engine in the two-stroke IC space.

It is not a Diesel cycle (constant pressure while burning), or a variation of the Diesel cycle which burns almost all of the fuel during the power stroke. It is a constant-volume-while-burning cycle. In accordance with one aspect of the present invention, there are provided new concepts of controlling the motion of the pistons in IC engines that can overcome many of the inefficiencies of the prior art.

The pistons are coupled to a crankshaft to hold the pistons at or near End Of Stroke (EOS) for at least the time fuel is burned in the combustion chamber or at least the time fuel is injected into the combustion chamber, during maximum power generation. In accordance with another aspect of the present invention, there are provided IC engines that replace the connecting rods with scotch yokes, including slots in the yokes where the bearings ride that are shaped differently than those in state-of-the-art scotch yokes. Prior art scotch yokes have slots with straight sides perpendicular to the motion of the pistons which control the pistons in a conventional manor. The present invention includes curved scotch yoke slots holding the pistons at or near EOS for an extended time period. In accordance with yet another aspect of the present invention, there are provided IC engines including cams on crankshaft throws holding the pistons at or near EOS for an extended time period.