Free piston internal combustion engine with piston head having a radially moveable cap

摘要

A free piston internal combustion engine includes a combustion cylinder having an inside surface. A piston which is reciprocally disposed within the combustion cylinder includes a piston head and a plunger rod. The plunger rod is attached to the piston head and has a longitudinal axis. The piston head includes a non-metallic cap and a metallic skirt. The cap has a outside surface lying closely adjacent to and defining a bearing surface with the inside surface of the combustion cylinder. The cap is substantially immovably attached to the skirt in a direction parallel to the longitudinal axis of the plunger rod, and is movably attached to the skirt in a radial direction relative to the longitudinal axis of the plunger rod.