Rocket piston internal combustion engine

An improvement to the crank piston for reciprocating operation within a cylinder of any internal combustion engine includes a short cylinder defining a recess under a piston crown port plate closing the recess to define a bounce gas chamber therein. A rocket piston disc is disposed for reciprocation within the bounce gas chamber. The plate defines a plurality of openings therethrough to permit communication of combustion gas between the engine cylinder and the chamber above the piston disc. The rocket piston disc is sized to allow combustion gas to leak behind the disc into the bounce gas chamber. The disc operates as a rocket piston by first trapping a fraction of peak pressure as bounce gas between the disc and the bottom of the cylinder, next compressing this bounce gas in response to auto-ignition gas pressure exerted through the ports, and then providing supplemental crank power as the rocket piston disc is pushed upward to seat by the increased pressure bounce gas. In one embodiment, a support member in the form of a conical spring can be provided to hold the rocket piston disc near a seat in the port plate. The spring force rate may be increased to raise bounce pressure if desired.