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.

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.

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.

Multiphase electromagnetic machines, such as free-piston engines or compressors, may require, or supply, a pulsed power profile from or to a DC bus, respectively. The pulsed power profile may include relatively large fluctuations in instantaneous power. Sourcing, sinking, or otherwise exchanging power with an AC grid, via an inverter, may be accomplished by using an energy storage device and a DC-DC converter coupled to a DC bus. The energy storage device may aid in smoothing the pulsed power profile, while the DC-DC converter may aid in reducing fluctuations in voltage across a DC bus due to energy storage in the energy storage device.

Various embodiments of the present disclosure are directed towards free-piston combustion engines. As described herein, a driver section may be provided in a free-piston combustion engine for storing energy during an expansion stroke. The driver section may be configured to store sufficient energy to perform the subsequent stroke. In some embodiments, the driver section may be configured to store sufficient energy so as to enable the engine to operate continuously across engine cycles without electrical energy input. A linear electromagnetic machine may be provided in a free-piston combustion engine for converting the kinetic energy of a piston assembly into electrical energy.

A vehicle may include an electromechanical energy recovery system and be configured to perform a method for its operation.

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.

An object of the present invention is to provide a method and a system for implementing the method so as to alleviate the disadvantages of a reciprocating combustion engine and gas turbine when generating power. The invention is based on the idea of arranging a multifunction valve inside a combustion chamber to create more favourable favorable conditions for combustion process. The multifunction valve may act as an output valve, but it can also provide additional final compression to contents of the compression chamber and it may even capture part of energy released in a combustion process.

Various embodiments of the present disclosure are directed towards free-piston combustion engines. As described herein, a driver section may be provided in a free-piston combustion engine for storing energy during an expansion stroke. The driver section may be configured to store sufficient energy to perform the subsequent stroke. In some embodiments, the driver section may be configured to store sufficient energy so as to enable the engine to operate continuously across engine cycles without electrical energy input. A linear electromagnetic machine may be provided in a free-piston combustion engine for converting the kinetic energy of a piston assembly into electrical energy.

A combined heat and power microgrid system is provided that stores energy in the form of compressed air that can then be utilized as needed in the form, of electricity. The compressed air may be generated with energy from multiple electrical energy sources, such as renewable energy sources. The energy stored as compressed air/heat is used to charge a battery by utilizing a pulley system and a barrel housing that transfers kinetic energy generated by the release of the compressed air to an array of piezoelectric generators that can produce electricity, which is stored in the second battery. In addition, water may be extracted from the compressed air storage tank. In this way, energy produced by the renewable sources can be accessed during periods of high need or low production and water may be collected.