Patent ID: 8601988

Claim:
A free piston assembly comprising: at least one piston accommodating device; at least one piston device having a first piston surface and a second piston surface facing away from said first piston surface which is moveable in a linear manner in the corresponding piston accommodating device; an expansion space which is arranged in the piston accommodating device and delimited by the first piston surface; wherein the piston device is arranged to be driven by the action of a medium which expands in the expansion space; a resilience space arranged in the at least one piston accommodating device, said resilience space being delimited by the second piston surface; wherein the resilience space is connected to at least one pre-compression chamber in fluidic manners; and at least one linearly moveable active element that is connected to the piston device; wherein the at least one piston accommodating device comprises a side from which there is guided out the at least one linearly moveable active element; wherein the at least one active element is guided through the at least one pre-compression chamber; wherein at least one channel, which has a first opening and a second opening, is arranged on the at least one active element; wherein the position of the first opening and the second opening in relation to the resilience space and a pre-compression space of the pre-compression chamber is dependent on the position of the at least one active element; and wherein the pre-compression space and the resilience space are connected together in fluidic manner via the channel in one or more positions of the piston device.