Apparatus and method for sealing internal combustion engines

A four-stroke internal combustion engine having an inlet and an exhaust comprised of:

• a generally fixed piston, such that the piston has an outer surface, and such that the outer surface has at least one non-planar sealing ring groove;
• a hollow cylinder having one closed end,
• the cylinder having an inner diameter approximately the same as the diameter of the piston, and configured such that the cylinder overlaps the piston, so that the cylinder may rotate and translate relative to the piston;
• a chamber between the piston and the closed end of the cylinder,
• such that the volume of the chamber can be varied by the translation of the cylinder relative to the piston;
• a cam means which couples the translation of the cylinder to its rotation;
• at least one opening in the piston which serves as an intake port;
• at least one opening in the piston which serves as an exhaust port;
• at least one recess in the hollow cylinder which serves as a transfer port;
• such that the piston intake port and cylinder transfer port are in periodic registry during the cylinder rotation to allow fluid to enter the chamber through the intake port and transfer port, and such that the piston exhaust port and cylinder transfer port are in periodic registry during the cylinder rotation to allow fluid to exit the chamber through the transfer port and the exhaust port;
• and
• at least one non-planar primary sealing ring, such that the sealing ring is substantially contained in the non-planar sealing ring groove.