US Patent 7464673 Single-ended barrel engine with double-ended, double roller pistons

An internal combustion barrel engine includes an engine housing and an elongated power shaft. A combustion cylinder and a guide cylinder are spaced apart and disposed on a common cylinder axis. A double-ended piston includes a combustion end disposed in the combustion cylinder so as to define a combustion chamber between the combustion end and the closed end of the combustion cylinder. A guide end is disposed in the guide cylinder. Combustion occurs only in the combustion cylinder and does not occur in the guide cylinder.