Patent ID: 6925971

Claim:
A free piston engine comprising: an energy generation and control assembly having a first side and a second side in opposed relation to the first side; a first combustion cylinder assembly located adjacent to the first side and including a first cylinder liner having a generally cylindrical wall that defines a first engine cylinder, which is generally centered about an axis of motion, and with the wall including at least one exhaust port extending therethrough; a second combustion cylinder assembly located adjacent to the second side and including a second cylinder liner having a generally cylindrical second wall that defines a second engine cylinder, which is generally centered about the axis of motion, and with the second wall including at least one second exhaust port extending therethrough; an inner piston assembly including a first inner piston having a head portion, an opposed rear portion, and a cylindrical side wall extending therebetween, with the cylindrical side wall generally centered about and extending in the direction of the axis of motion, and with the first inner piston being located and telescopically slidable within the first engine cylinder along the axis of motion a generally predetermined distance that defines a first piston stroke; a second inner piston having a head portion, an opposed rear portion, and a second cylindrical side wall extending therebetween, with the second cylindrical side wall generally centered about and extending in the direction of the axis of motion, and with the second inner piston being located and telescopically slidable within the second engine cylinder along the axis of motion a generally predetermined distance that defines a second piston stroke; and a push rod mounted to the first inner piston and the second inner piston and operatively engaging the energy generation and control assembly; and wherein the location in the wall of the at least one exhaust port is such that the cylindrical side wall will cover the at least one exhaust port for only a portion of the first piston stroke, and the location in the second wall of the at least one second exhaust port is such that the second cylindrical side wall will cover the at least one second exhaust port for only a portion of the second piston stroke.