| Patent Number |
Title Of Patent |
Date Issued |
| RE38337 |
Centering system for free piston machine |
December 2, 2003 |
| A centering apparatus for a free piston Stirling engine including a pressure regulator valve which connects a passageway between the work space and the back space when both (a) the average pressure in the back space exceeds the average pressure in the work space as a result of the pi |
| 7453241 |
Electronic controller matching engine power to alternator power and maintaining engine frequency |
November 18, 2008 |
| A feedback control method and circuit for inclusion in a control system of an electrical power generating source that comprises a free piston Stirling engine driving a linear alternator. An instantaneous value of a variable, V.sub.internal, is continuously derived from other sensed and |
| 7437878 |
Multi-stage pulse tube cryocooler with acoustic impedance constructed to reduce transient cool d |
October 21, 2008 |
| The cool down time for a multi-stage, pulse tube cryocooler is reduced by configuring at least a portion of the acoustic impedance of a selected stage, higher than the first stage, so that it surrounds the cold head of the selected stage. The surrounding acoustic impedance of the selecte |
| 7409833 |
Dual mode compressor with automatic compression ratio adjustment for adapting to multiple operat |
August 12, 2008 |
| An apparatus and method for compressing gas refrigerant using two different compressors operated alternatively in a series or parallel mode for obtaining two different compression ratios and thereby provide efficient operation for both a relatively lower suction pressure and a relati |
| 7372255 |
Detection of the instantaneous position of a linearly reciprocating member using high frequency |
May 13, 2008 |
| A piston position sensing circuit for sensing the instantaneous position of a piston of a free piston Stirling machine or a compressor mechanically connected to a reciprocating member of a linear electric motor or alternator. A source of a high frequency, alternating, electrical sign |
| 7266947 |
Temperature control for free-piston cryocooler with gas bearings |
September 11, 2007 |
| A cryocooler having two operating modes so that its operating range is broadened, its gas bearing system is maintained in an operable state and it can utilize piston stroke modulation for energy efficiency. A piston stroke modulator modulates the piston stroke when the commanded piston |
| 7210312 |
Energy efficient, inexpensive extraction of oxygen from ambient air for portable and home use |
May 1, 2007 |
| Apparatus and method for separating oxygen directly from air, operating at substantially atmospheric pressure and recuperating energy used for cooling incoming air. An ambient air input leads from the atmosphere to a vessel for confining gases. A cryocooler has a cooled surface in the |
| 7043835 |
Method for centering a workpiece on the cylindrical axis of a bore |
May 16, 2006 |
| A method and system for precisely centering a workpiece within a cylindrical bore such that the center of the workpiece is coaxial with the central axis of the bore. An arbor is used within the cylindrical bore to sense and calculate the location of the central axis. The position of |
| 7000390 |
Stirling cycle engine or heat pump with improved heat exchanger |
February 21, 2006 |
| A Stirling cycle machine heat exchanger and a method for making the heat exchanger including, forming an annular ring of a solid heat conductive mass, the annular ring having a central axis and having axially opposite faces. A plurality of passages are drilled through the annular ring an |
| 6993917 |
Coupling for heat transfer member |
February 7, 2006 |
| A heat transfer member having an external heat transfer member including an insertion hole having an adaptor ring inserted thereinto, and at least one of a base blocking protrusion and a grove blocking protrusion formed on a predetermined portion of the surface of the base confronting th |
| 6991023 |
Involute foil regenerator |
January 31, 2006 |
| A regenerator having a plurality of involute foils disposed in an annular gap between an inner cylindrical tube and an outer cylindrical tube. The involute shape of the foils provides uniform spacing throughout the entire regenerator and substantial surface area for fluid contact. |
| 6920967 |
Controller for reducing excessive amplitude of oscillation of free piston |
July 26, 2005 |
| An apparatus for detecting and reducing excessive amplitude of oscillation of a free piston slidably mounted in a housing. The housing has a vibration absorber, including a mass mounted through a spring to the housing. The mass reciprocates relative to the housing along a path in a p |
| 6880452 |
Spring standoff for a reciprocating device |
April 19, 2005 |
| A spring standoff for a reciprocating device, the standoff having a generally cylindrical body and having a window in a circumferential surface of the body, and a flange at each end of the body, one flange to be coupled to a planar spring of the reciprocating device, and the other fl |
| 6817221 |
Wound regenerator method |
November 16, 2004 |
| A method of forming a wound roll, such as a regenerator, including the steps of inserting wires at the lateral edges of an elongated strip as the strip is being wound around a spool. Spacers, such as localized bumps, are formed on the strip to space strip layers apart to form uniform gap |
| 6782700 |
Transient temperature control system and method for preventing destructive collisions in free pi |
August 31, 2004 |
| The free piston cooler transient temperature control system of the present invention eliminates collisions during the transient cool-down period in a free piston cooler upon start-up. The transient temperature control system incorporates a free piston cooler, having a cold head and a war |
| 6684637 |
Parallel slot heat exchanger |
February 3, 2004 |
| A heat exchanger in which a fluid and a surface transfer thermal energy effectively with a smaller pressure drop than is conventionally realized. In a preferred embodiment, gas at one end of a piston flows into a piston chamber and passes radially through a plurality of axial slots forme |
| 6536326 |
Control system and method for preventing destructive collisions in free piston machines |
March 25, 2003 |
| In a free piston machine, initial collisions of the piston with structures at the end of the cylinder are detected and generate a change in the magnitude of a perturbation signal, which is applied to the summing junction of a closed loop feedback control system controlling a piston f |
| 6446336 |
Heat exchanger and method of constructing same |
September 10, 2002 |
| A method of forming a heat exchanger apparatus on a housing wall. The heat exchanger includes inner and outer annular rings. The rings have heat radiating, high surface area fins attached on oppositely facing surfaces. The inner ring has a radially outwardly facing surface that abuts the |
| 6293184 |
Gas bearing and method of making a gas bearing for a free piston machine |
September 25, 2001 |
| A gas bearing structure including a cylindrical core and a cylindrical sleeve. The core has a radially outwardly facing surface with longitudinal and circumferential grooves formed thereon. The sleeve has a radially inwardly facing surface that sealingly abuts the outer core surface. The |
| 6199381 |
DC centering of free piston machine |
March 13, 2001 |
| In a free piston machine, a coil is mounted to its housing and magnetically linked to a permanent magnet or electromagnet on its piston member to form a linear motor. The coil and magnet are either added to embody the invention or are part of an AC linear alternator or AC linear motor wh |
| 6170442 |
Free piston internal combustion engine |
January 9, 2001 |
| A free piston internal combustion engine having improved valve timing. A pair of oppositely disposed combustion chamber passageways extending between the combustion chamber and the earth's atmosphere, each have a combustion chamber valve for controlling the passage of gas through the |
| 6038874 |
Refrigeration circuit having series evaporators and modulatable compressor |
March 21, 2000 |
| A refrigeration system having a modulatable compressor and a Rankine cycle refrigeration circuit having at least two evaporators. The flow rate of the compressor is modulated in response to the sensed temperature of the masses being cooled, and the control circuit switches valves to cont |
| 6035637 |
Free-piston internal combustion engine |
March 14, 2000 |
| This invention is an efficient free-piston internal-combustion engine having an expansion ratio greater than the compression ratio and preferably with gas bearings supporting the piston. The use of gas bearings in combination with high-temperature ceramic materials allows the engine |
| 5873246 |
Centering system for free piston machine |
February 23, 1999 |
| A centering apparatus for a free piston Stirling engine including a pressure regulator valve which connects a passageway between the work space and the back space when both (a) the average pressure in the back space exceeds the average pressure in the work space as a result of the pi |
| 5775273 |
Free piston internal combustion engine |
July 7, 1998 |
| A free piston internal combustion engine having improved valve timing. A pair of oppositely disposed combustion chamber passageways extending between the combustion chamber and the earth's atmosphere, each have a combustion chamber valve for controlling the passage of gas through the |
| 5715693 |
Refrigeration circuit having series evaporators and modulatable compressor |
February 10, 1998 |
| A refrigeration system having a modulatable compressor and a Rankine cycle refrigeration circuit having at least two evaporators. The flow rate of the compressor is modulated in response to the sensed temperature of the masses being cooled, and the control circuit switches valves to cont |
| 5642622 |
Refrigerator with interior mounted heat pump |
July 1, 1997 |
| A refrigerator having a heat pump mounted within the insulated portion of the refrigerator cabinet which is cooled by the heat pump. The heat pump is a Stirling cycle or Rankine cycle heat pump, is used to cool the interior of the refrigerator cabinet, and is mounted in an insulated |
| 5642088 |
Magnet support sleeve for linear electromechanical transducer |
June 24, 1997 |
| A reciprocating magnetic body support structure for a linear motor or a linear alternator is claimed. The body comprises a cylindrical, metallic support sleeve having a plurality of longitudinal slots evenly spaced around the circumference of the sleeve. An equal number of magnet segment |
| 5592073 |
Triac control circuit |
January 7, 1997 |
| A common and inexpensive integrated 555 timing circuit is used to vary the timing of triac firing pulses in response to a control voltage. A trigger pulse generator generates a pulse at each zero cross-over of an AC line. This pulse initiates a variable, one shot pulse generator which ge |
| 5537820 |
Free piston end position limiter |
July 23, 1996 |
| A piston end position limiter for a free piston machine of the type having a piston sealingly reciprocating in a cylinder and separating a work space bounded at one end of the piston from a second space bounded at the opposite end of the piston. The work space and the second space contai |
| 5525845 |
Fluid bearing with compliant linkage for centering reciprocating bodies |
June 11, 1996 |
| An improved mechanical transducer of the type having a body reciprocating in a chamber, the body being linked to a housing by a linkage including an axially compliant spring. An anti-friction fluid bearing applies a lateral centering force upon the body and a linkage component of the lin |
| 5502968 |
Free piston stirling machine having a controllably switchable work transmitting linkage between |
April 2, 1996 |
| Free piston Stirling coolers and engines are improved by a variable power transmitting linkage connecting the displacer to the piston and coupling more power from the displacer to the piston while piston displacement exceeds a selected limit than coupled while piston displacement is less |
| 5496153 |
Method and apparatus for measuring piston position in a free piston compressor |
March 5, 1996 |
| A method of measuring the distance at closest approach between the piston of a free piston compressor and the cylinder head. The method derives measurements of both the alternating and average components of piston position from direct measurements of the voltage and current applied to |
| 5461859 |
Centering system with one way valve for free piston machine |
October 31, 1995 |
| A piston centering system for a free piston machine. The invention uses a centering passageway which is in communication between a work space and a second space which spaces are formed in a housing and are separated by a piston which reciprocates in a cylinder in the housing. The centeri |
| 5450521 |
Pulse width modulator |
September 12, 1995 |
| An electrical circuit and method for generating a continuous train of width modulated pulses. A square wave is generated and a delay circuit provides a delayed analog of the square wave. A controllable duration one-shot multivibrator generates a modulating pulse having a duration proport |
| 5385021 |
Free piston stirling machine having variable spring between displacer and piston for power contr |
January 31, 1995 |
| Free piston Stirling coolers and engines are improved by a spring coupling the displacer to the piston and having a variable spring constant. Controllable variation of its spring constant permits controllable variation of displacer stroke, engine power output and cooler thermal pumpi |
| 5342176 |
Method and apparatus for measuring piston position in a free piston compressor |
August 30, 1994 |
| A method of measuring the distance at closest approach between the piston of a free piston compressor and the cylinder head. The method derives measurements of both the alternating and average components of piston position from direct measurements of the voltage and current applied to |
| 5156005 |
Control of stirling cooler displacement by pulse width modulation of drive motor voltage |
October 20, 1992 |
| The displacement of a Stirling cycle cryocooler is controlled as a function of temperature by controlling the amplitude of the fundamental component of an AC signal which is applied to the motor at its operating frequency. A pulse train is generated, having a frequency which is a harmoni |
| 5148066 |
Linear generator or motor with integral magnetic spring |
September 15, 1992 |
| The invention relates to thermomechanical transducers drivingly linked to a linear motor or alternator, preferably a free piston Stirling engine in which the piston is drivingly linked to the field magnet of an alternator. There are symmetric and coaxial secondary magnets attached at opp |
| 5003777 |
Asymmetric gas spring |
April 2, 1991 |
| In a free piston Stirling machine, a gas spring apparatus for applying two distinctly different spring rates to the displacer during the displacer's excursion past a center point in opposite ends of the work space. The apparatus comprises a cylinder formed in a gas spring housing, in whi |
| 4945726 |
Leaky gas spring valve for preventing piston overstroke in a free piston stirling engine |
August 7, 1990 |
| The invention is for the prevention of power piston overstroke in a Stirling cycle machine, wherein there is a gas valve which vents the gas spring acting upon the displacer. The valve and its accompanying control system switch on a leak in the gas spring to vent the gas spring upon |
| 4926123 |
Precision variable pitch compensation winding for displacement transducer |
May 15, 1990 |
| A compensation winding for improving the linearity of a displacement transducer. The displacement transducer is the type having an electrically conducting non-ferromagnetic wall which moves in telescoping relation with the coil and is excited by a signal at a sufficiently high frequency |
| 4912929 |
Variable gas spring for matching power output from FPSE to load of refrigerant compressor |
April 3, 1990 |
| The power output of a free piston Stirling engine is matched to a gas compressor which it drives and its stroke amplitude is made relatively constant as a function of power by connecting a gas spring to the drive linkage from the engine to the compressor. The gas spring is connected to |
| 4912409 |
Actuator displacement transducer having external flux excluding tube |
March 27, 1990 |
| A linear displacement transducer has an elongated current conducting, tubular coil which is mounted to an end cap in a hydraulic or pneumatic cylinder and extends into a hole bored in the piston/piston rod unit within the cylinder. An electrically conducting, nonferromagnetic tube li |
| 4888951 |
Phase synchronization and vibration cancellation for free piston Stirling machines |
December 26, 1989 |
| An apparatus and method for synchronizing the phase of a pair of free piston Stirling machines without changing the design parameters or operating characteristics from the operating mode of each machine alone. Energy is coupled from corresponding gas spaces of each machine into an in |
| 4888950 |
Magnetic driven hydrodynamic lubrication system for free piston stirling engine |
December 26, 1989 |
| The apparatus of the invention relates to a free piston Stirling engine that contains a power piston and a displacer piston which each reciprocate in a coaxial cylinder. At least one piston is hydrodynamically lubricated to avoid friction based wear by spinning the piston about its axis |
| 4866378 |
Displacement transducer with opposed coils for improved linearity and temperature compensation |
September 12, 1989 |
| The relative displacement of two bodies is measured by moving an electrically conducting, non-ferromagnetic wall means in proportion to the relative movement of the bodies in order to increase its overlapping, telescoping relationship to a first current conducting coil while simultan |
| 4864232 |
Temperature compensation for displacement transducer |
September 5, 1989 |
| A temperature compensation structure for a displacement transducer of the type having a coil and an electrically conducting, non-ferromagnetic wall moving in telescoping relationship with the coil and excited by a signal at a sufficiently high frequency so that skin effect in the wall pe |
| 4805408 |
Stirling engine power regulation system |
February 21, 1989 |
| The power output of a free piston Stirling engine is regulated by a valve in the gas flow path from the cold space through the regenerator to the hot space. The valve causes restriction of the gas flow path as in response to piston excursion beyond a selected excursion amplitude. Inc |
| 4802332 |
Sliding surface lubrication particularly advantageous for a free piston stirling engine |
February 7, 1989 |
| A Stirling cycle engine is provided with gas cavities at an interface between an engine piston and a mating surface that guides the piston in its reciprocative motion to thereby achieve improved lubrication with the resulting gas film. |
