Abstract: A clamping apparatus for allowing pre-close-out access to the head of a Stirling machine and facilitating subsequent close-out welding of the head. The head is axially separable into removable and fixed portions, each portion having an end that engages the other. Each portion has an annular flange extending radially outwardly at its engaging end, and each flange has an annular groove. O-rings are seated in the grooves. A temporary sealing ring surrounds and engages the O-rings. Clamping rings, having axially facing end surfaces along their interfacing axial edges, seat against axially opposite sides of the abutting annular flanges. The clamping rings have a plurality of holes spaced annularly around the rings and the holes of one ring are axially aligned with the holes in the other. Fasteners pass through each pair of holes and draw the rings together when tightened, thereby drawing the fixed and removable portions of the head together and securing them against relative axial movement.

Abstract: 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 relatively higher suction pressure. This system avoids an unbalanced mass flow rate when the compressors are operated in series by unloading a downstream one of the compressors. When operated in the series mode, refrigerant is bypassed back to a suction inlet of the downstream compressor during a portion of a compression stroke of the downstream compressor for equalizing the mass flow rate through the two compressors.

Abstract: 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 signal applies a high frequency signal to the winding circuit of the linear alternator or motor. A filter circuit is connected to the winding circuit and passes electrical signals at the frequency of the high frequency source and blocks signals at the operating frequency of reciprocation. A peak detector circuit is connected to the filter circuit and detects the peak of the filter circuit output signal to provide an instantaneous peak magnitude that is proportional to the instantaneous piston position.

Abstract: 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 stroke exceeds the minimum stroke and maintains the minimum stroke when the commanded stroke is less than the minimum stroke. A heater applies heater power to the thermal load when the commanded piston stroke is less than the minimum piston stroke. A closed loop feedback control system is used which has two branches of its dynamic leg. One branch controls the modulation of the cryocooler and the second, parallel branch controls the modulation of the heater.

Abstract: 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 vessel for directly condensing oxygen from the air at substantially atmospheric pressure. The cryocooler cools the cold surface to a temperature greater than the boiling point temperature of nitrogen and not greater than the boiling point temperature of oxygen for condensing oxygen. A liquid/gas separator separates the liquid oxygen from residual gases which both flow out through separate outputs. Air is propelled through the system at substantially atmospheric pressure by an air impeller. A heat exchanger recovers cooling energy and dehumidifies incoming air by transferring heat from the incoming air to outgoing gases.

Abstract: 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 the workpiece is also sensed so that it can be aligned with the central axis. A computer system is used to perform the calculations and provide an indication of alignment of the workpiece and the central axis. The position of the central axis and the workpiece are found via a location determining system that may incorporate electromechanical and optical position sensing systems. For instance, a plurality of light transmitters and light receivers may be used to generate and transmit beams of light used in determining positions. The method has particular application to free piston machines, and particularly free piston coolers.

Abstract: 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 and through the opposite faces to provide passages for the flow of a fluid through the passages and transfer of heat energy between the mass and the fluid. The passages are preferably parallel to the axis and have a circular cross section and are arranged in a plurality of circumferentially spaced sets of passages, each set having a plurality of radially spaced passages.

Abstract: 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 the inserted adaptor ring inside the insertion groove, for increasing the coupling strength of the external radiating member and the adaptor ring and the transition member.

Abstract: 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.

Abstract: 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 phase relationship to the piston. A sensor is mounted near the mass for detecting the amplitude of oscillation of the mass. A controller is connected to the sensor for reducing the amplitude of oscillation of the piston when the amplitude of oscillation of the mass reaches a predetermined maximum.

Abstract: 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 flange to be coupled to a sealing container of the reciprocating device. The body generally concentrically houses at least a portion of a reciprocating rod coupled to the planar spring of the reciprocating device.

Abstract: A securing device for a spring is provided, the device having a generally hollow spring support having a spring mount having a projection on an inner side of the spring support and configured to support the spring, the device further having a generally annular coupling ring configured to connect to the spring support to secure the spring to the spring support.

Abstract: 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 flange to be coupled to a sealing container of the reciprocating device. The body generally concentrically houses at least a portion of a reciprocating rod coupled to the planar spring of the reciprocating device.

Abstract: 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 gaps. An offset is added to the angle of rotation between each spacer-forming step to inhibit the nesting of bumps in the cavities of adjacent strip layers.

Abstract: 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 warm end, a cold head temperature sensor, a relational interface, and a temperature controller. The cold head temperature sensor senses the temperature of the cold head and generates a temperature signal. The relational interface is in communication with the temperature signal and contains a predetermined relationship between the cold head temperature and a maximum piston stroke during the transient cool-down temperature range. The relational interface generates a transient range maximum allowable stroke signal from the temperature signal and the predetermined relationship.

Abstract: 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 the inserted adaptor ring inside the insertion groove, for increasing the coupling strength of the external radiating member and the adaptor ring and the transition member.

Abstract: 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 formed through the piston sidewall and into a gap between the piston sidewall and the surface of the housing in which the piston slidably mounts. Between each pair of through-slots, longer axial slots are formed that extend only partially through the sidewall radially, and almost the entire length of the piston. Thus, around the circumference of the piston the slots alternate in structure between through-slots and longer slots. Gas that enters the gap through the through-slots flows circumferentially through the gap and into the longer slots. The gas exits the longer slots at the opposite end of the piston from the first gas space.

Abstract: 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 force. The change is applied in a direction to reduce piston amplitude. In embodiments in which maximization of piston amplitude is desirable, the magnitude of the perturbation signal is also varied in the opposite direction in the absence of collisions to increase piston amplitude of oscillation so that operation then hunts between initial nondestructive collisions and a non-colliding maximum amplitude of piston oscillation.

Abstract: 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 interior surface of the housing sidewall. The outer ring has a radially inwardly facing surface that abuts the exterior surface of the housing sidewall. When displaced longitudinally along the ring axes, which are coincidental, the sidewall is clampingly engaged therebetween, and an excellent thermal flow path is formed. Heat transferred into the inner fins from a working gas is conducted to the inner ring, through the sidewall, into the outer ring, then into the outer fins. Air impinging upon the outer fins absorbs the heat from the outer fins.

Abstract: 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 piston deflecting a spring, and simultaneously (b) the instantaneous pressure in the back space exceeds the instantaneous pressure in the work space. A diaphragm spans across an actuator housing cavity, dividing the cavity into an upper chamber and a lower chamber. A connector valve is linked to the diaphragm for opening and closing the valve upon displacement of the diaphragm. When the average back space pressure exceeds the average work space pressure, the diaphragm is displaced to open the valve, connecting the work space and the back space in fluid communication. A check valve permits the flow of gas in only one direction: from the back space to the work space.