Abstract: A heat exchanger system for a Stirling engine includes a heater connected to the expansion space by a pair of parallel flow ducts, and a cooler connected to the compression space by a pair of parallel flow ducts. A circulator is arranged in one of the heater ducts and one of the cooler ducts to continuously circulate working fluid from the working space, through the heat exchanger, and back into the same working space. The expansion and compression processes are thereby made more isothermal and the heat exchangers may be made smaller, more effective and with a lower pressure drop.

Abstract: A free-piston Stirling engine compressor includes a hermetic vessel enclosing a working space in which a displacer reciprocates for displacing working gas through a heater, regenerator and a cooler so as to create a pressure wave. The pressure wave acts on an engine diaphragm to displace fluid in an adjacent hydraulic chamber to drive a power piston on a power stroke. The power piston acts in the hydraulic chamber against an adjacent compressor diaphragm to compress a gas in a compression space and expell the compressed gas through an exhaust valve. A control system is provided for adjusting the mean pressure in the engine working space to maintain a predetermined proportional relationship between the mean pressure in the compression space and the engine working space.

Abstract: A method and apparatus for controlling a resonant piston compressor of the type comprising an electrodynamic linear reciprocating motor adapted to be driven cyclically by an alternating current power source and having at least one piston coupled to and adapted to be driven within a selectively valved working cylinder by the linear reciprocating motor in synchronism with the frequency of the alternating current power source. Enclosed volumes of gas act as resilient gas springs coacting with the piston and with the linear reciprocating motor to form a mechanical resonant system having a resonant frequency substantially centered on the frequency of the alternating current power source. A midstroke porting arrangement is responsive to the position of the resonant piston for selectively communicating a gas spring control valve with said gas springs.

Abstract: A gaseous fuel combustor for a Stirling engine includes a shell mounted on the engine, and air inlet and exhaust ports formed in the shell. An annular cylindrical recuperator communicates with the inlet and exhaust ports for preheating the combustion air with the heat from the exhaust. An annular burner surrounds the dome shaped engine heater head for mixing gaseous fuel with the air and burning it at the outer peripheral edge of the heater head. The combustion products converge upwardly in a narrow space between a ceramic partition and the heater head dome so that the heat flux is constant. The combustion products exhaust through a axial hole in the center of the ceramic partition and travel back outward over the top of the partition to the annular recuperator.

Abstract: A free-piston Stirling engine usable as a heat pump has a closed vessel filled with helium working gas which is heated at the bottom end and cooled at the top end. The vessel contains a displacer supported for axial reciprocal oscillation on a gas spring post mounted on the vessel. The displacer shuttles the working gas from end to end in the vessel, alternately heating and cooling the gas. The vessel is sealed with a flexible diaphragm which flexes in response to the pressure wave generated in the vessel as the working gas is alternately heated and cooled. When the diaphragm flexes, it displaces hydraulic fluid in a hydraulic chamber and drives a power piston for driving a linear alternator and a gas compressor. A gas spring operating on a second hydraulic cylinder on the other side of the power piston stores part of the energy of the piston stroke and returns it for the return stroke.

Abstract: A linear electrodynamic machine is disclosed having permanent magnet excitation and an end flux leakage control. A flux carrying body having a plurality of annular magnets of alternating radially oriented polarities is disposed concentrically with respect to a stator having a plurality of annular wound coils. Relative axial reciprocation of the body and stator causes a reversal of the flux linking the coils while the flux in the body remains substantially constant. Focusing magnets provided on each end of the body and axial extensions provided on the stator insure uniformity of the alternating flux linking the coils and a constant flux intensity in the body to achieve high efficiencies.

Abstract: A free-piston Stirling engine usable as a heat pump has a closed vessel filled with helium working gas which is heated at the bottom end and cooled at the top end. The vessel contains a displacer supported for axial reciprocal oscillation on a gas spring post mounted on the vessel. The displacer shuttles the working gas from end to end in the vessel, alternately heating and cooling the gas. The vessel is sealed with a flexible diaphragm which flexes in response to the pressure wave generated in the vessel as the working gas is alternately heated and cooled. When the diaphragm flexes, it displaces hydraulic fluid in a hydraulic chamber and drives a power piston for driving a linear alternator and a gas compressor. A gas spring operating on a second hydraulic cylinder on the other side of the power piston stores part of the energy of the piston stroke and returns it for the return stroke.

Abstract: A lip seal for preventing the mixing of seawater with an oil cavity around a marine stern tube includes an annular radial flange attached to one end of an axially extending bushing which is encircled by a garter spring. An axially extending foot projects from the bushing into the oil cavity and includes a hydrodynamic profile on its inner surface. A pocket is formed in the sealing face of the bushing and is pressurized with oil by the hydrodynamic profile on the bushing. The pressurized oil pocket balances the water pressure on the outside of the seal, and the hydrodynamic profile forms a fluid film which lubricates the seal and provides the balancing pressure for the pocket. A series of vents can be provided to vent excess oil pressure in the pocket to prevent leakage of oil out of the pocket into the water.