A free piston apparatus includes a piston receptacle in which a piston device having a piston is reciprocable along an axis. The piston receptacle includes or forms a combustion chamber delimited by a wall arrangement forming an inlet opening for the supply of fresh gas and an outlet opening for the removal of exhaust gas. Fresh gas is suppliable via a supply conduit. The free piston apparatus includes a housing for fresh gas which is connected to the supply conduit in a flow direction of the fresh gas being supplied. The housing forms a settling chamber for fresh gas which surrounds the piston receptacle at least in sections in the region of the inlet opening in a circumferential direction of the axis. The settling chamber opens into the combustion chamber via the inlet opening.

Disclosed is a linear expander includes: a body portion including a suction hole through which a fluid having a first pressure flows in, a discharge hole through which the fluid flows out with a second pressure that is lower than the first pressure, and first and second holes connecting an expansion space formed between the suction hole and the discharge hole, a first linear generating portion and a second linear generating portion respectively causing pistons provided in the first hole and the second hole to linearly reciprocate to generate an induced electromotive force with an expansion force generated when the fluid having the first pressure expands to the fluid having the second pressure, a suction valve opening and closing the suction hole, and a discharge valve and closing the discharge hole.

Various embodiments of the present invention are directed toward a linear combustion engine, comprising: a cylinder having a cylinder wall and a pair of ends, the cylinder including a combustion section disposed in a center portion of the cylinder; a pair of opposed piston assemblies adapted to move linearly within the cylinder, each piston assembly disposed on one side of the combustion section opposite the other piston assembly, each piston assembly including a spring rod and a piston comprising a solid front section adjacent the combustion section and a gas section; and a pair of linear electromagnetic machines adapted to directly convert kinetic energy of the piston assembly into electrical energy, and adapted to directly convert electrical energy into kinetic energy of the piston assembly for providing compression work during the compression stroke.

A free piston apparatus includes a piston receptacle in which a piston device having a piston is reciprocable along an axis. The piston receptacle includes or forms a chamber delimited by a wall arrangement forming an inlet opening and an outlet opening. A cooling device is arranged on the piston receptacle for cooling the wall arrangement. The cooling device includes or forms a cooling channel arranged radially outside on the wall arrangement. The cooling channel has first and second cooling regions axially on opposing sides of the outlet opening. The piston receptacle includes or forms an outlet chamber, arranged outside on the wall arrangement, for exhaust gas exiting via the outlet opening. The cooling channel has a third cooling region which flow-connects the first cooling region and the second cooling region along the outlet chamber and is positioned at least in sections radially outside of the outlet chamber.

The present invention relates to a free-piston linear apparatus, comprising a piston arranged within a cylinder, said piston being configured for linear displacement within the cylinder; a combustion chamber arranged on one side of said piston and a gas expansion chamber arranged on an opposite side of said piston, wherein said piston is drivable under the action of a fuel medium expanding in the combustion chamber; an exhaust vent arranged to release exhaust gas from the combustion chamber to an exhaust system, wherein said exhaust system comprises a heat exchanger configured to transfer residual heat from said exhaust gas to said gas expansion chamber in order to heat the gas expansion chamber; and wherein said gas expansion chamber comprises at least one gas port for injecting and/or releasing gas into/from the gas expansion chamber.

A free piston apparatus includes a piston receptacle in which a piston device having a piston is reciprocable along an axis. The piston receptacle includes a combustion chamber delimited by a wall arrangement forming an inlet opening for the supply of fresh gas and an outlet opening for the removal of exhaust gas. The free piston apparatus includes an inflow device, which has the inlet opening and is configured such that fresh gas flowing into the combustion chamber is directed to an incident flow region in the combustion chamber arranged offset axially to the inlet opening, which incident flow region is arranged off-center relative to the axis. A method for operating a free piston apparatus includes operating an inflow device which has an inlet opening configured such that fresh gas is directed to an incident flow region in a combustion chamber offset axially to the inlet opening.

A free piston apparatus includes a piston receptacle in which a piston device having a piston is linearly reciprocable. The piston receptacle includes or forms a combustion chamber delimited by a wall arrangement forming a first opening and a second opening. The openings include an inlet opening for the supply of fresh gas and an outlet opening for the removal of exhaust gas for a uniflow scavenging of the combustion chamber. Movement of the piston device is controllable by a control device. The bottom dead center of the piston can be adjustable such that when the piston adopts the bottom dead center, the first opening is partially unblocked and partially blocked for adjusting a free cross sectional area of the first opening. An opening duration can also be adjustable. A method for operating a free piston apparatus includes controlling movement of a piston device with a control device.

Disclosed is a thermodynamic cycle process, performing transfer between mechanical and heat energies, by changing a state of a fluid, including: an expansion of the fluid, an energy retrieval from the fluid expansion, a step of powering a liquid pump or a gas compressor with the retrieved energy, using a cyclic free piston expander which alternatively changes direction of the free piston sliding: by alternatively: closing the fluidic communication between the both opposite sides of the free piston, to make different from each other the pressures applied respectively thereon, so the free piston slides in a first direction, opening a fluidic communication between both opposite sides of the free piston, to make equal to each other the pressures applied respectively thereon, so the free piston slides in a second direction opposite to the first direction, the free piston sliding, directly and mechanically, opening and closing, the fluidic communication.

The present invention relates to a free-piston linear apparatus, comprising a piston arranged within a cylinder, said piston being configured for linear displacement within the cylinder; a combustion chamber arranged on one side of said piston and a gas expansion chamber arranged on an opposite side of said piston, wherein said piston is drivable under the action of a fuel medium expanding in the combustion chamber; an exhaust vent arranged to release exhaust gas from the combustion chamber to an exhaust system, wherein said exhaust system comprises a heat exchanger configured to transfer residual heat from said exhaust gas to said gas expansion chamber in order to heat the gas expansion chamber; and wherein said gas expansion chamber comprises at least one gas port for injecting and/or releasing gas into/from the gas expansion chamber.

Various embodiments of the present invention are directed toward a linear combustion engine, comprising: a cylinder having a cylinder wall and a pair of ends, the cylinder including a combustion section disposed in a center portion of the cylinder; a pair of opposed piston assemblies adapted to move linearly within the cylinder, each piston assembly disposed on one side of the combustion section opposite the other piston assembly, each piston assembly including a spring rod and a piston comprising a solid front section adjacent the combustion section and a gas section; and a pair of linear electromagnetic machines adapted to directly convert kinetic energy of the piston assembly into electrical energy, and adapted to directly convert electrical energy into kinetic energy of the piston assembly for providing compression work during the compression stroke.