A differential pressure motor comprising two working pistons and a rod that move in a hollow space. Walls defining the hollow space have five openings. A valve piston moves between and against the working pistons and can be driven by the working pistons. The valve piston with the five openings forms a valve with which an alternate impact of a first pressure and a second pressure on the working pistons is controllable when the pressures are applied to three of the five openings such that the working pistons periodically move which drives a periodic movement of the valve piston. Also disclosed are a surgical drive system with, a medical lavage system for the debridement of soft tissue and/or bone tissue having, and a medical device for brushing, rasping or sawing soft tissue and/or bone tissue with such a differential pressure motor, and a method for operating a differential pressure motor.

An assembly with a piston reciprocated with the aid of a floating head in fluid communication with the piston. The assembly may utilize a floating head that is shifted in position to promote reciprocation of the piston through the aid of pressure supplied to the floating head from a pressure volume regulator. Alternatively, the floating head may be in fluid communication with the piston at one side of the head and isolated at the other side. In this manner changing volume and pressure at this other side of the head during reciprocation may ultimately lead to floating head movement toward the piston, thereby promoting the continued reciprocation. Additional efficiencies may also be realized through unique hydraulic layouts for both operating and working fluid circulations.

An internal combustion may include a cylinder having a first combustion chamber at one end and a second combustion chamber at an opposing end, first and second cylinder heads located at an end of the first and second combustion chambers, respectively, and a double-faced piston slidably mounted within the cylinder. The piston may be configured to move in the cylinder in a first stroke from one end to another. The first stroke may include an expansion stroke portion and a non-expansion stroke portion. The non-expansion stroke portion may include a momentum stroke portion. The non-expansion stroke portion may include a scavenging phase. The engine may further include first and second piston rod portions extending from opposite faces of the piston. Passageways in the piston rod portions may be configured to communicate gases between a combustion chamber and other locations.

Provided is a power generation system with which it is possible to perform efficient power generation. The power generation system comprises: an evaporation chamber; a reciprocal heat-insulating cylinder provided with a forward-side expansion chamber and a backward-side expansion chamber; an operating fluid supply/ejection means which performs a supply flow passageway forming operation and an ejection flow passageway forming operation in an alternating and reciprocal manner; a heat-insulating expansion chamber; a liquefied operating fluid recirculating means; and a compression/liquefaction recirculating means. The heat-insulating expansion chamber may be provided separately on both the ejection flow passage downstream side of the forward-side expansion chamber and on the ejection flow passage downstream side of the backward-side expansion chamber.

An engine utilizing multiple closed loop heat exchangers. The engine makes use of a first exchanger dedicated to a given chamber of a piston assembly. This exchanger is configured to provide both heating and cooling to the chamber for changing the volume thereof in stroking the piston. The second exchanger is configured similarly to provide both heating and cooling to another chamber at the opposite side of the piston for correspondingly facilitating a change in its volume as the piston is stroked. This unique configuration allows for the working substance in the chambers, generally an operating CO.sub.2 fluid, to effectively remain in a supercritical state for the substantial duration of the thermal cycle.

Provided is a power generation system with which it is possible to perform efficient power generation. The power generation system comprises: an evaporation chamber; a reciprocal heat-insulating cylinder provided with a forward-side expansion chamber and a backward-side expansion chamber; an operating fluid supply/ejection means which performs a supply flow passageway forming operation and an ejection flow passageway forming operation in an alternating and reciprocal manner; a heat-insulating expansion chamber; a liquefied operating fluid recirculating means; and a compression/liquefaction recirculating means. The heat-insulating expansion chamber may be provided separately on both the ejection flow passage downstream side of the forward-side expansion chamber and on the ejection flow passage downstream side of the backward-side expansion chamber.

An internal combustion engine may include an engine block, a cylinder defining at least one combustion chamber, and a piston in the cylinder. The piston may travel in a first stroke from one end to an opposite end of the cylinder, and may be sized relative to the cylinder to enable an expansion stroke portion of the first stroke while the piston travels under gas expansion pressure, and a momentum stroke portion of the first stroke for the remainder of the first stroke following the expansion stroke portion. A passageway may be formed in the piston rod to communicate gas flow between a first combustion chamber and an area external to the cylinder when the piston is in a first position, and to communicate gas flow between a second combustion chamber and an area external to the cylinder when the piston is in a second position.

An internal combustion engine may include an engine block, a cylinder defining at least one combustion chamber, and a piston in the cylinder. The piston may travel in a first stroke from one end to an opposite end of the cylinder, and may be sized relative to the cylinder to enable an expansion stroke portion of the first stroke while the piston travels under gas expansion pressure, and a momentum stroke portion of the first stroke for the remainder of the first stroke following the expansion stroke portion. A passageway may be formed in the piston rod to communicate gas flow between a first combustion chamber and an area external to the cylinder when the piston is in a first position, and to communicate gas flow between a second combustion chamber and an area external to the cylinder when the piston is in a second position.

An opposed, free-piston engine includes a pair of adjacent cylinders, each extending from a first cylinder end to a second cylinder end along an elongate axis and having a first cylinder housing a first pair of opposed, free pistons including a first piston housed towards the first cylinder end and a second piston housed towards the second cylinder end; a second cylinder housing a second pair of opposed, free pistons having a third piston and a fourth piston; and a pair of link rods including a first link rod and a second link rod. The first link rod has a first link rod end and a second link rod end, the second link rod having a third link rod end and a fourth link rod end.

An internal combustion may include a cylinder having a first combustion chamber at one end and a second combustion chamber at an opposing end, first and second cylinder heads located at an end of the first and second combustion chambers, respectively, and a double-faced piston slidably mounted within the cylinder. The piston may be configured to move in the cylinder in a work stroke from one end to another. The work stroke may include an expansion stroke portion, a momentum stroke portion, and a compression stroke portion. The engine may further include first and second piston rod portions extending from opposite faces of the piston. Passageways in the piston rod portions may be configured to communicate gases between a combustion chamber and a location outside the cylinder.