NOVELTY - The converter (1) has a piston outer body (8) mounted in a combustion cylinder (2) along a longitudinal axis (16). An internal gas passage (11) is connected to a valve stem (18) that slidably extends away from a top surface (10). Another gas passage (22) is near an end (7) of a cylinder wall (5), where the body is connected to a magnetic sleeve (23). A stationary magnetic field coil (24) provides an axial force on a piston (4). The stem extends slidably through an outer surface (44), and a frame part (27) is attached to a valve stem part extending outside the piston.    USE - Used for converting energy and providing different thermodynamic cycles e.g. Atkinson-like cycle, as a pump in an internal combustion engine e.g. 2-stroke engine and 4-stroke engine, in automotive propulsion of vehicle e.g. small mid-size and large hybrid vehicle for feeding electrical power to an electric drive motor and spark ignition (SI) engine, and in a stationary applications for generation of electrical power.    ADVANTAGE - The converter comprising high speed processing systems provides accurately timed magnetic impulses, thus fast accurate and variable control of the port timing is possible without the need for complicated mechanical structures. The delaying of the inlet valve opening and/or matching of the outlet ports and various thermodynamic cycles can be obtained. The need for the vulnerable piston, connecting rod and crankshaft construction is avoided and hence the system is lightweight, allows higher pressures and greater reliability, and increases the specific output of the generator. A full balance of forces is possible, thus reducing mechanical friction, size and manufacturing cost.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional view of a linear free piston energy converter comprising two opposed co-axial pistons.    Linear free piston energy converter (1)    Combustion cylinder (2)    Piston (4)    Cylinder wall (5)    End (7)    Piston outer body (8)    Top surface (10)    Internal gas passage (11)    Side surface (15)    Longitudinal axis (16)    Valve stem (18)    Gas passages (21, 22)    Magnetic sleeve (23)    Stationary magnetic field coil (24)    Frame parts (26, 27, 28)    Power coils (30)    Stationary field coils (31, 32)    Outer surface (44)