Abstract: The cryogenic refrigerator includes a movable displacer within an enclosure having first and second chambers of variable volume. A refrigerant fluid is circulated in a fluid path between said chambers and correlated with movement of the displacer. A spool valve controls introduction of high pressure fluid and low pressure fluid to said chambers in a manner so that such flow is correlated with the pressure difference across said valve.

Abstract: In a cryogenic refrigerator, a valve member reciprocates to control fluid to and from chambers of variable volume. The valve member is moved in one direction by a cam and in the opposite direction by a fluid spring.

Abstract: An improved cryogenic refrigerator having a drive mechanism suitable for use with gap or clearance seals is disclosed. The drive mechanism includes two reciprocating members, e.g. piston and regenerator/displacer, driven by a common rotating drive shaft. The regenerator/displacer portion of the drive shaft includes a roller at one end in engagement with a rod base plate for driving a rod connected to the regenerator/displacer and a spring for returning the regenerator/displacer simultaneously with the withdrawal of the drive shaft. The piston portion of the drive shaft is connected to a first end of a hollow body. The second end of the hollow body which is opposite the first end has the piston rigidly affixed thereto. The hollow body has a portion adjacent the first end supported by a guide whereby the piston is substantially isolated from side force loads during reciprocation.

Abstract: The cryogenic refrigerator includes a movable displacer within an enclosure having first and second chambers of variable volume. A refrigerant fluid is circulated in a fluid path between said chambers and correlated with movement of the displacer. A spool valve controls introduction of high pressure fluid and low pressure fluid to said chambers. The displacer movement is controlled by an electric motor which has a cam for reciprocating the spool valve member. The refrigerator is converted into a source of heat by reversing the direction of rotation of said electric motor.

Abstract: In a refrigeration system such as a split Stirling system, fluid seals associated with the reciprocating displacer are virtually dragless clearance seals. Movement of the displacer relative to the pressure variations in the working volume of gas is retarded by a discrete braking element. Because it is not necessary that the brake providing any sealing action, the brake can be designed for greater durability and less dependence on ambient and operating temperatures. Similarly, the clearance seal can be formed of elements having low thermal expansion such that the seal is not temperature dependent. In the primary embodiments the braking element is a split friction brake.

Abstract: A thermodynamic oscillator having a displacer (5) and a piston (3) (further displacer) movable due to pressure fluctuations at the resonance frequency of the oscillator. The displacer (5) and the piston (3) are located in a working space (11, 15) which is filled with working medium and can be connected through a release valve (51, 125, 167) and a supply valve (53, 129, 169), respectively, to simple reservoir (55) filled upon working medium with an increase and a decrease, respectively, of the ambient temperature with respect to a nominal temperature. The valves (51, 53, 125, 129, 167, 169) have an opening pressure which is a function of the ambient temperature. The average pressure and the resonance frequency of the oscillator can thus be stabilized at a variable ambient temperature.The oscillator can be operated as a cold-gas engine, a hot-gas engine (motor), a heat pump or a current generator.

Abstract: Positive displacement isothermal gas cycle machinery is designed with explicit control of the heat flow between the gas, the walls of the chamber and a thermal reservoir externally of the chamber. The control is achieved by providing a large chamber wall area to chamber volume ratio through the use of bellows-like walls having a configuration that ensures during each stroke numerous heat exchanges between the working gas and the bellows-like walls. The machinery includes Stirling cycle heat pumps and motors and isothermal compressors. Significant gains in thermal efficiency, up to a factor of 2, are attainable because the largest inefficiency in all isothermal machinery is imperfect control of heat flow. A regenerator for the isothermal machinery minimizes cycle losses due to gas transfer friction, gas thermal conduction, dead volume, regenerator heat mass, regenerator heat mass thermal skin depth, and regenerator mass thermal conductivity in the gas flow direction.

Abstract: An improved thermal engine of the type having a displacer body movable between the hot end and the cold end of a chamber for subjecting a fluid within that chamber to a thermodynamic cycle and having a work piston driven by the fluid for deriving a useful work output. The work piston pumps a hydraulic fluid and a hydraulic control valve is connected in line with the hydraulic output conduit such that the flow of hydraulic fluid may be restricted to any desired degree or stopped altogether. The work piston can therefore be controlled by means of a controller device independently from the movement of the displacer such that a variety of engine cycles can be obtained for optimum engine efficiency under varying load conditions. While a Stirling engine cycle is particularly contemplated, other engine cycles may be obtained by controlling the movement of the displacer and work pistons.

Abstract: In a cryogenic refrigerator, a refrigerant is circulated in a fluid flow path between first and second chambers by the movement of a displacer means. A slide is connected to the displacer means and reciprocated by a motor. The slide has an axial passage communicating the first and second chambers. The slide has a piston for varying the volume of gas in a third chamber during its reciprocation. The need for a separate compressor is eliminated.

Abstract: A miniature cryogenic cooling system having low microphonics and thermophonics. The apparatus includes a cold finger incorporating primary and secondary working volumes and their associated regenerative beds. Both volumes are adapted to effect cooling. A displacer reciprocates within the cold finger under the influence of push-pull pressure waves from a dual compressor assembly. The cold finger includes an arrangement for providing pneumatic cushioning of the reciprocating displacer to control displacer slamming.

Abstract: A four piston hydraulic pump driven by a four cylinder free-piston Stirling engine has four stepped pistons operating out of phase in pairs. The hydraulic fluid pumped between the hydraulic cylinder can be tapped for hydraulic power. The stepped pistons give the option of utilizing low flow/high pressure, or high flow/low pressure. The non-utilized flow ensures that the timing between pistons will always remain correct. Since the arrangement is symmetrical, it remains balanced.

Abstract: A split Stirling refrigerator includes a pneumatically driven displacer, the displacer is driven substantially through an entire stroke by the pressure differential across a piston element extending from the displacer. A small linear trimming motor is provided to assure proper phasing of the displacer movement with the refrigerator pressure wave, to prevent overstroke, and to assure complete stroke of the displacer.

Abstract: A Stirling cycle heat engine, specially suitable for use in environments subject to acceleration or large temperature variations, including a free and reciprocating displacer piston fitted with a non-contact device which acts with increasing force to oppose further movement whenever the piston overshoots desired limits of its movement. The device may include a magnet which is carried by the piston shaft and which experiences repulsion from like poles of magnets carried by the shaft housing.

Abstract: A refrigerator has a cold producer with a pneumatically-operated displacer for displacing a working, cold-producing gas. The pneumatic and working gas-supply control is separate from the cold producer and connected thereto by tubes having volumes less than the maximum volumes of the portions of the chamber supplied thereby.

Abstract: In a gas cycle refrigerator having a compressor (10), a gas expansion vessel containing a displacer (3, 37), a switch valve means (11, 12) between the vessel and the compressor, and a heat accumulator (15) between gas expansion chambers (21, 23) at both ends of the displacer within the vessel, the conduit between the switch valve means and one gas expansion chamber (21) has a resistance to gaseous cooling medium which substantially corresponds to the pressure loss in the heat accumulator so that pressure will change substantially at the same rate in both the gas expansion chambers at both ends of the displacer (21, 23) and thus will not undergo an undesirable force which may occur due to a difference in pressure between the gas expansion chambers. A compact structure of switch valve in such refrigerator is also disclosed.

Abstract: A cryogenic refrigeration is disclosed for operation in a first mode wherein an electrical motor reciprocates a displacer, and in a second mode wherein the displayer is reciprocated by both the motor and fluidic pressure, and in a third mode wherein the displacer is reciprocated by fluidic pressure.

Abstract: Valves for controlling process gas at the cold end of an expansion engine are fluid actuated. The actuating fluid is controlled by a solenoid actuated spool valve positioned at ambient temperature. The fluid is cooled in a thermally regenerative flow path extending between the solenoid actuated valve and the fluid actuated valve.

Abstract: A Stirling heat pump driven by a Stirling engine has its stroke limited under conditions of decreasing pump load. This stroke limitation is accomplished by effecting the flow of gas from the engine to the heat pump in response to a maximum piston stroke. Preferably, a valved passageway is formed in communication between the gas in the engine and the gas of the pump. The passageway is valved by a means which normally blocks the flow of gas but opens when the piston of either the pump or the engines strokes to an extreme selected position. The passageway opens into the engine and into the pump at zones so that when the valve is open the zones are at a pressure differential which will cause a flow of gas from the engine to the pump. By this means the power delivered by the heat engine portion of the machine can be made to be equal to the power absorbed by the heat pump at all conditions of heat pump temperature differential.

Abstract: A new and improved resonant free-piston Stirling engine and method of operation employing a novel virtual rod displacer is described. A rod is secured to and reciprocally moves with the displacer within the Stirling engine and has a rod piston area formed on the end of the rod remote from the displacer with the rod piston area also being subjected to the working gas periodic pressure wave. Suitable support bearings are designed within the Stirling engine housing for reciprocatingly supporting the displacer and rod assembly within the Stirling engine with a set of opposed acting gas springs being provided to act on the displacer end and rod assembly area end of the displacer and rod assembly.

Abstract: A heat actuated heat pumping apparatus and process having two working chambers to provide a Vuilleumier cycle for space conditioning. The working chamber volumes are in pressure communication with each other in the vicinity of intermediate thermal exchange means in each volume equalizing the pressure between the two working volumes with one module acting as the driver for the heat pumping action of the second module. Pressure communication may be maintained through a floating piston thereby providing two different intermediate heat rejection temperature levels resulting in a four temperature level Vuilleumier heat pump. The apparatus and process of this invention reduces mechanical complexity and improved thermal exchange in a heat pump system suitable for large air conditioning applications and hot water heating as well as small refrigeration and cryogenic applications.

Abstract: A compressor, pump, or alternator apparatus is designed for use with a resonant free piston Stirling engine so as to isolate apparatus fluid from the periodically pressurized working fluid of the Stirling engine. The apparatus housing has a first side closed by a power coupling flexible diaphragm (the engine working member) and a second side closed by a flexible diaphragm gas spring. A reciprocally movable piston is disposed in a transverse cylinder in the housing and moves substantially at right angles relative to the flexible diaphragms. An incompressible fluid fills the housing which is divided into two separate chambers by suitable ports. One chamber provides fluid coupling between the power diaphragm of the RFPSE and the piston and the second chamber provides fluid coupling between the gas spring diaphragm and the opposite side of the piston. The working members of a gas compressor, pump, or alternator are driven by the piston.

Abstract: A construction of a variable volume chamber that allows cycling of a working fluid to occur substantially isothermally is disclosed. The present invention provides a fixed, rigid heat conductive element within the chamber. The heat conductive element has a surface area which is large relative to that of the chamber itself. The volume of the chamber is varied by a mechanism which meshes with the heat conductive element to minimize dead volume. As a result the heat conductive element absorbs and returns heat energy to and from the working fluid in an efficient fashion, resulting in a high degree of isothermalization of the working fluid.

Abstract: A fluid-operated refrigerating machine for developing extremely low temperature by using a displacer reciprocatable within a refrigeration cylinder and a fluid-operated piston solidly connected to the displacer. A mechanical converter which converts a reciprocating motion into a rotary motion is operatively connected to the piston to limit the stroke of the piston thereby to prevent the displacer from its collision with the end walls of the refrigeration cylinder and ensure smooth operation of the displacer. For controlling gas to and from the refrigeration cylinder as well as to and from the driving chamber of the piston, a single rotary valve driven by a motor is used. In an embodiment, the rotary valve is operatively connected to the converter and thus the displacer is not only under fluid-operation but also is mechanically operated by the motor through the converter.

Abstract: The cryogenic refrigerator includes a movable displacer within an enclosure having first and second chambers of variable volume. A refrigerant fluid is circulated in a fluid path between said chambers and correlated with movement of the displacer. A spool valve controls introduction of high pressure fluid and low pressure fluid to said chambers. The displacer movement is controlled by an electric motor which has a cam for reciprocating the spool valve member.

Abstract: A regenerative, thermodynamic cyclic process for refrigerating machines employing a high-speed compressor. During an expansion phase, a gaseous coolant is pumped by this compressor directly out of a working volume and transferred, under compression, into an intermediate tank or into a second working volume, and during a following compression phase, the coolant is pumped by the compressor out of the intermediate tank or the second working volume, while using a reversing valve actuated to operate in synchronism with a displacer movement, and returned to the first working volume of the refrigerating machine. The expended compression work is thus recovered.

Abstract: A resonant free-piston Stirling engine having a new and improved start-up and control method and system. A displacer linear electrodynamic machine is provided having an armature secured to and movable with the displacer and having a stator supported by the Stirling engine housing in juxtaposition to the armature. A control excitation circuit is provided for electrically exciting the displacer linear electrodynamic machine with electrical excitation signals having substantially the same frequency as the desired frequency of operation of the Stirling engine.

Abstract: A free piston displacer control means based on an offset axis mass attached o a crankshaft flywheel in which the rotating crankshaft reciprocates the piston displacer by driving the piston during the momentum of the stroke and by static braking at the end of each stroke at the period of maximum pressure exchange across the cooler frictional seal.

Abstract: A hydraulic drive system operating from the periodic pressure wave produced by a Stirling engine along a first axis thereof and effecting transfer of power from the Stirling engine to a load apparatus therefor and wherein the movable, or working member of the load apparatus is reciprocatingly driven along an axis substantially at right angles to the first axis to achieve an arrangement of a Stirling engine and load apparatus assembly which is much shorter and the components of the load apparatus more readily accessible.

Abstract: A method and apparatus for increasing the refrigeration capacity of a displacer-expander type cryogenic refrigerator pneumatically actuated by a rotary valve by increasing the number of ports of the rotary valve to increase reciprocating speed of the displacer without increasing speed of rotation of the valve.

Abstract: A torsionally flexible seal formed with alternating layers of elastic and reinforcing material provides a gas-tight barrier between a drive shaft and a portion of the Stirling engine housing surrounding a passageway through which the drive shaft extends. The shaft is connected to a series of mechanical linkage devices located within the housing which transmits power between the linearly reciprocative power piston and rotationally reciprocative drive shaft and which eliminates substantially the side forces exerted on the piston.

Abstract: The invention relates to a heat pump device comprising a pair of chambers and a plurality of elements extending within both chambers. A working fluid is disposed in both of the chambers and a displacer means is positioned in each of the chambers such that they are movable within their respective chambers. Both of the displacer means have a wall that divides their respective chambers into two zones, a regenerator material that is housed therein, a plurality of elements extending outwardly from and in proximity to the elements extending within the respective chamber, and at least one passageway communicating through each displacer means and through the respective regenerator material for the working fluid to flow therethrough between the zones. There is a drive means for reciprocably moving both of the displacer means in their respective chamber between the respective zones of the chamber.

Abstract: A miniature cryogenic system preferably operating in a manner similar to a split Stirling cycle utilizes a cold finger with a solid, low weight displacer and a stationary regenerative material external to the displacer. The regenerative material preferably surrounds the displacer and extends from a fluid inlet to a cooled end plate of a housing. The displacer has a central channel that receives an auxiliary displacer that carries a regenerative material in an internal cavity. A second fluid inlet located at the end of the housing opposite the cooled end communicates with the regenerative material held in the auxiliary displacer. The main and auxiliary displacers preferably have associated heat exchangers at their cooling ends and the cooling end of the auxiliary displacer is located to pre-cool the fluid passing from the first inlet to the cooled end plate.

Abstract: A free piston Stirling engine inertial cancellation system includes a displacer reciprocating in a hermetic vessel enclosing a working space to circulate working gas through a heater, regenerator, and cooler to create a pressure wave in the working space. A power piston, mechanically unconnected to the displacer, is reciprocally driven by the pressure wave to produce a power output stroke in one direction and a working gas compression stroke in the other direction. The displacer and the power piston form substantially a first mass in the working space. A second mass, outside the working space and preferably including an alternator plunger, is mounted in the vessel and is coupled to the first mass momentum exchange relationship.

Abstract: An apparatus for effecting the lubrication of expansible chamber devices of the type having a cylinder with a piston reciprocating therein and having fluid flowing in and out of the chamber. The invention is particularly suitable for free piston Stirling engines and pumps. A torque force is applied to the piston causing it to spin sufficiently to entrain and drag along its outer surface some of the fluid in the expansible chamber so as to separate its outer surface from the wall of the cylinder.

Abstract: A pneumatic space and an expansion space are provided in a cooling head hng a double-ended piston. A fluid line from the cooler compressor feeds directly into the expansion space, and, via a fluid delay, into the pressure space. In response to the fluid pressure waves in the lines, the piston is first moved in one direction by fluid in the expansion space and in the opposite direction by fluid in the pneumatic space.

Abstract: A dual pneumatic volume means in the ambient end of a free displacer cyroic cooler to provide strong pneumatic braking and dwell times of the displacer movement at both the top dead center and bottom dead center of the displacer waveform. A second pneumatic piston is positioned between the end of the cooler housing and extends into the first pneumatic piston attached to the displacer to form a pneumatic spring volume within the first piston to accomplish the strong pneumatic braking.

Abstract: A power control is disclosed for a free piston Stirling engine having a hermetically sealed vessel enclosing a working space in which oscillates a displacer for circulating working gas through a heater, a regenerator and a cooler for creating a pressure wave in the working gas which acts against a power piston for a producing power stroke. The displacer includes a post mounted in a well which forms a gas spring and cooperates with the working gas pressure wave to maintain the displacer in axial reciprocating motion. The post includes a tapered portion which reciprocates opposite a proximity probe to produce a unique signal for each axial position of the displacer to provide stroke, phase and amplitude information regarding the displacer motion. A gas spring volume control is provided, controlled by the displacer sensor, for adjusting the gas spring stiffness to control the amplitude and phase of the displacer required to produce the power to meet the engine load requirements.

Abstract: A torsionally flexible seal formed with alternating layers of elastic and reinforcing material provides a gas-tight barrier between a drive shaft and a portion of the Stirling engine housing surrounding a passageway through which the drive shaft extends. The shaft is connected to a series of mechanical linkage devices located within the housing which transmits power between the linearly reciprocative power piston and rotationally reciprocative drive shaft and which eliminates substantially the side forces exerted on the piston.

Abstract: The displacer and piston of a Stirling engine are provided with inner cylindrical walls which serve as bearing surfaces in close fitting, sliding engagement with the outer bearing surface of a longitudinally extending, tubular center post. The internal bore of the center post is in fluid communication with the bounce space. Center porting is provided by passages in the piston, displacer and tubular wall of the center post so that fluid communication is provided periodically between the work space and bounce space and between the displacer gas spring and the bounce space. In this manner, the piston and displacer remain properly positioned within the engine housing.

Abstract: This invention comprises a cryogenic cooling device operating in the manner f a split Stirling cycle engine whereby a sinusoidal pressure-wave generator distal to a regenerator displacer piston and accompanying cylinder, individually compresses in a delayed manner and expands a contained volume of gas in an expander housing respective to regenerator displacer piston travel to bring about a cooling effect in an attached displacer housing.

Abstract: A Stirling heating pump has a working piston acting upon a compression chamber and actuated by a crank drive accommodated in a housing, and a diaphragm bellows surrounding the working piston for sealing the compression chamber from the housing and having an inner hollow communicating with the former. Pressure variations in the interior of the diaphragm bellows are compensated by a pressure throttling element arranged between the compression chamber and the inner hollow of the diaphragm bellows, and a compensating diaphragm expansible in the housing and having an inner hollow communicating with the inner hollow of the diaphragm bellows serves to form a closed flow circuit.

Abstract: A free piston Stirling engine has a hermetic vessel containing a displacer piston and a power piston coupled to each other and to the vessel by gas springs. An additional mass is coupled to the vessel by a gas spring which is tuned to the operating frequency of the engine geometrically. The vibration absorber is effective at all engine frequencies because the absorber gas spring follows the engine working gas mean pressure and changes the absorber natural frequency as the engine frequency changes.

Abstract: A Stirling cycle machine in which the compressor/expander is in driving connection with a first electromagnetic unit, and in which a second electromagnetic unit is connected to the displacer and can be operated as an externally-variable control of the movements of the displacer. In one form of the invention the second unit acts as an electromagnetic damper upon movements which the displacer makes in natural response to those of the compressor. In another form of the invention the second unit positively drives the displacer and the two units are interconnected by means including a phase-shifting device whereby movements of compressor and displacer are kept of equal frequency but variable as to phase difference. Transducers sensitive to position, velocity or accelaration may improve control of the movements of compressor and displacer, and a temperature sensor associated with the "cold finger" of the displacer may further improve control of the movements of the latter.

Abstract: The cryogenic refrigerator includes a movable displacer within an enclosure having first and second chambers of variable volume. A refrigerant fluid is circulated in a fluid path between said chambers by movement of the displacer. A spool valve controls introduction of high pressure fluid and low pressure fluid. The displacer movement is controlled by fluidic pressure instead of an electric motor.

Abstract: The cryogenic refrigerator includes a movable displacer within an enclosure having first and second chambers of variable volume. A refrigerant fluid is circulated in a fluid path between said chambers by movement of the displacer. A spool valve controls introduction of high pressure fluid and low pressure fluid. The displacer movement, at least at top dead center and bottom dead center is controlled by an electric motor.

Abstract: The cryogenic refrigerator includes a movable displacer within an enclosure having first and second chambers of variable volume. A refrigerant fluid is circulated in a fluid path between said chambers by movement of the displacer. A spool valve controls introduction of high pressure fluid and low pressure fluid. The displacer movement is controlled by an electric motor.

Abstract: Swash plate driving means for cryogenic coolers wherein multiple compress and regenerators are driven. The swash plate driving means may drive one or more compressors off one or both sides of each swash plate, and one or more regenerators may simultaneously be driven by separate swash plates. The swash plates are formed to provide flat topped and bottomed repetitive pressure waves.

Abstract: A gas bearing for the axially reciprocating displacer and power piston members in a free piston Stirling engine includes a bearing sleeve having a pair of interconnected annular pressure plenums formed by ribs on the outer surface of the sleeve which form a seal with the inner walls of a cylinder in which the sleeve is seated. The outer side of the raised ribs provide a second set of interconnecting drain plenums. A source of a high pressure gas, pressurized internally by the engine itself, is connected to the pressure plenum which communicates with the axially reciprocating members through a multitude of narrow orifices. The bearing gas is drained into the second or drained plenum through a large number of larger sized orifices.

Abstract: A free-piston Stirling engine includes a hermetically sealed vessel enclosing a working space within which reciprocates a displacer. The displacer is mounted at its cold end on mounting means including a first portion, preferably a post, which reciprocates in a second portion, preferably a sleeve, fixed to the vessel. The relatively reciprocating mounting means includes a gas spring. The mounting means also reduces the effective area exposed to a pressure wave of the displacer cold end relative to the displacer hot end so that the thermodynamic system provides power by virtue of the differential areas of the displacer ends. The periodic pressure wave together with the gas spring maintain the displacer in oscillation.

Abstract: A free piston Stirling engine includes a hermetically sealed vessel enclosing a working space which is filled with a working gas such as helium. A displacer is mounted in the working space on a suspension apparatus for axial reciprocation to displace working gas back and forth sequentially through a heater, a regenerator, and a cooler to create a cyclic pressure wave which drives a power piston. The displacer is connected to a mounting flange fixed to the vessel by a bellows which permits the displacer to move axially. A diaphragm is connected to the mounting flange and seals an oil cavity whose sides are defined by the bellows. The top of the oil cavity is formed by a transverse wall in the displacer, in which is formed a cylinder which receives a stationary piston mounted on a spider in the oil cavity and fastened to the mounting flange.