Abstract: A method for operating a pulse tube cryocooler system wherein in the event the mean pressure of the working gas within the fixed volume of the cryocooler undergoes a change, the operation of the system is kept from severe degradation by changing the frequency of the pressure wave generator driving the cryocooler directly with the change in the mean pressure.

Abstract: An integrated cryopump and 2 stage pulse tube refrigeration system (100) comprising a cryopump, a compressor for a pulse tube refrigerator, a pulse tube refrigerator located within the vacuum chamber of the cryopump where the hot ends of the pulse tubes (165,175) are connected to each other through a buffer volume (180), are integral to the cryopump vacuum chamber hosing, and a buffer volume (180) is connected to the hot ends (117,119) of the pulse tubes (165,175) through flow restrictors (145,150).

Abstract: A pulse tube refrigerator comprising a cold head, wherein the cold head comprises at least one pulse tube (6) and at least one regenerator (7); the cold head having a cold end (8) and a warm end (5), each end being provided with respective heat exchangers (12, 13); wherein refrigerant is supplied (3) to the cold head; and wherein the warm end heat exchanger (13) is provided with a secondary cooling mechanism (16, 17) to improve the efficiency of the PTR.

Abstract: A thermocoustic device includes a housing with a thermal core supported in the housing and having a first and a second surface. The thermal core includes a first heat exchanger defining the first surface of the thermal core and a second heat exchanger defining the second surface of the thermal core. A main chamber is in fluid communication with the first surface of the thermal core and a secondary multiplier chamber is in fluid communication with the second surface of the thermal core. A working volume of a gaseous working fluid fills the main chamber, the multiplier chamber, and the thermal core at a pressure. An equilibrium pressure is defined as the pressure of the working volume of gaseous working fluids with the thermoacoustic device is in a non-operating mode.

Abstract: A pulse tube system for generating refrigeration for uses such as in magnetic resonance imaging systems wherein an oil-free compressor operating at a higher frequency generates pulsing gas which undergoes a frequency reduction and drives the pulse tube system at a more efficient lower frequency.

Abstract: A cryogenic chamber comprising an outer vacuum vessel (9), an inner cryogen vessel (11), a turret (40) housing a neck tube (8) itself providing external access to the inner cryogen vessel (11), and a pulse tube refrigerator (20) itself comprising at least one pulse tube and at least one regenerator tube. The pulse tube refrigerator is located within a vacuum contained between the outer vacuum vessel (9) and the inner cryogen vessel (11) and the pulse tube refrigerator (20) and the neck tube (8) share a single turret (40). The cooling stage(s) (6, 7) of the pulse tube refrigerator (20) is/are rigidly mechanically connected to the neck tube (8) by highly conductive thermal links. The pulse tube(s) and regenerator tube(s) are displaced away from the neck tube and from each other.

Abstract: A cryocooler cold end assembly is disclosed. The assembly includes a unitary external, outer housing. By constructing the housing from a single unitary metal shell, part count is reduced from prior art assemblies. Additionally, all brazing requirements previously necessary to secure and seal the components are eliminated. Further, due to one or more machining steps subsequent to manufacturing/forming the external sealed housing, the tolerances are improved. This allows for shrink to fit assembly of several components and also results in improved straight-line accuracy between the piston bore and the displacer cylinder. Due to this latter improvement, the need for a displacer liner is eliminated.

Abstract: The present invention relates to pulse tube refrigerators for recondensing cryogenic liquids. In particular, the present invention relates to the same for magnetic resonance imaging systems. In many cryogenic applications components, e.g. superconducting coils for magnetic resonance imaging (mri), superconducting transformers, generators, electronics, are cooled by keeping them in contact with a volume of liquified gases (e.g. helium, neon, nitrogen, argon, methane). In a first aspect, the present invention provides a pulse tube refrigerator PTR pulse tube refrigerator (PTR) arrangement within a cryogenic apparatus, wherein a regenerator tube of the PTR is finned. In this configuration the fins or baffles, are believed to increase the surface area available for distributed heat transfer from the helium atmosphere to the regenerator.

Abstract: In a Stirling cycle refrigerator, or in a method for controlling the operation of a Stirling cycle refrigerator, when it starts or stops being operated, or according to the detection result from position or temperature detecting means, the voltage supplied to a driving power source for driving a piston is controlled appropriately to prevent the piston from moving too far out of its movable range and thereby prevent breakage of a component resulting from collision between the piston and a displacer.

Abstract: An alloy made of heat treated material represented by Gd5(SixGe1?x)4 where 0.47?x?0.56 that exhibits a magnetic entropy change (??Sm) of at least 16 J/kg K, a magnetostriction of at least 2000 parts per million, and a magnetoresistance of at least 5 percent at a temperature of about 300K and below, and method of heat treating the material between 800 to 1600 degrees C. for a time to this end.

Abstract: Disclosed is a two-stage pulse tube cryopump cooling system in which the pulse tubes and valves are inline, with the hot ends of the pulse tubes at the top and the valve mechanism is at the bottom and the hot ends and buffer volume are cooled by an inline coolant line from the compressor input to the compressor output and attached in heat exchange relationship with the buffer volume.

Abstract: In the pressure oscillation generator 1, self-excited vibration is generated in a work transfer tube 30 by heating a heat input section 22 and also a resonator 50 is resonated, and when a work is inputted into a heat exchanger 20, the work is amplified by the heat exchanger 20, and is transferred to the heat transfer tube 30 and is then outputted to an output section 40. Because of the configuration, an outputted work can be amplified to a work larger than the inputted work, so that, by using a portion of the outputted work as energy for driving the cylinder 10, the pressure oscillation generator 1 can continuously be driven only by heating and without using electric energy generated by a large scale solar system or the like, which enables substantial size reduction of the pressure oscillation generator 1.

Abstract: A Stirling cycle refrigerating system has a pair of reversed Stirling cycle engines 3a and 3b, each comprising a warm head 8a and 8b of which the temperature rises as the reversed Stirling cycle engine is driven, a cold head 7a and 7b of which the temperature falls as the reversed Stirling cycle engine is driven, and a piston and a displacer that vibrate inside a cylinder along the axis thereof with an identical period and with a predetermined phase difference maintained. Inside a machine chamber 15, the pair of reversed Stirling cycle engines 3a and 3b is arranged coaxially with the axes thereof aligned with each other and with the cold heads 7a and 7b thereof facing away from each other, and the pistons or displacers of the pair of reversed Stirling cycle engines 3a and 3b are driven to vibrate in phase with each other.

Abstract: A two-stage hybrid cryocooler includes a first-stage Stirling expander having a first-stage regenerator having a first-stage-regenerator inlet and a first-stage-regenerator outlet, and a second-stage pulse tube expander. The second-stage pulse tube expander includes a second-stage regenerator having a second-stage regenerator inlet in gaseous communication with the first-stage regenerator outlet, and a second-stage regenerator outlet, and a pulse tube having a pulse-tube inlet in gaseous communication with the second-stage regenerator outlet, and a pulse-tube outlet. The second-stage regenerator and the pulse tube together provide a first gas-flow path between the first-stage regenerator and the pulse-tube outlet. A pulse tube pressure drop structure has a pulse-tube-pressure-drop inlet in gaseous communication with the pulse-tube outlet, and a pulse-tube pressure-drop outlet, and a gas volume is in gaseous communication with the pulse-tube pressure-drop outlet.

Abstract: A cryogenic refrigeration system includes an expansion nozzle having a high-pressure nozzle inlet and a low-pressure nozzle outlet, and a compressor having a compression device, such as a pair of opposing pistons, operable to compress gas within a compression volume. The compression volume has an inlet port and an outlet port. A flapper inlet valve has an inlet valve inlet, and an inlet valve outlet in gaseous communication with the inlet port of the compression volume. The inlet valve opens when a gaseous pressure at the inlet valve inlet is sufficiently greater than a gaseous pressure in the compression volume to overcome a spring force of the flapper inlet valve. A flapper outlet valve has an outlet valve inlet in gaseous communication with the outlet port of the compression volume, and an outlet valve outlet in gaseous communication with the nozzle inlet.

Abstract: To provide a preserving system capable of re-using vaporized nitrogen, and moreover, capable of always cooling the specimens at a predetermined temperature or lower. The preserving system comprising a cylinder and the preserving vessel which is supplied with liquid nitrogen from this cylinder, is provided with a Stirling refrigerator and a condensing chamber arranged outside of said preserving vessel, and the gas phase part of this condensing chamber is made to communicate with that of said preserving vessel and also the liquid phase part is made to communicate with that of said preserving vessel, and further the cooling part of said Stirling refrigerator is arranged in said condensing chamber, therefore, the nitrogen vaporized in the preserving vessel is cooled by the cooling part of the Stirling refrigerator in the condensing chamber and liquefied again, and so this liquid nitrogen can be reused for cooling the preserving vessel.

Abstract: The magnetic material for magnetic refrigeration according to the present invention has an NaZn13-type crystalline structure and comprises iron (Fe) as a principal element (more specifically, Fe is substituted for the position of “Zn”) and hydrogen (H) in an amount of 2 to 18 atomic % based on all constitutional elements. Preferably, the magnetic material for magnetic refrigeration preferably contains 61 to 87 atomic % of Fe, 4 to 18 atomic % of a total amount of Si and Al, 5 to 7 atomic % of La. The magnetic material for magnetic refrigeration exhibits a large entropy change in a room temperature region and no thermal hysteresis in a magnetic phase transition. Therefore, when a magnetic refrigeration cycle is configured using the magnetic material for magnetic refrigeration, a stable operation can be performed.

Abstract: A multi-stage thermoacoustic device includes a resonance tube mounted therein a plurality of stacks and a plurality of heat exchangers interlaid with each other adjacent to a second end of the resonance tube. A working fluid is filled in the resonance tube. A driver mounted on a first end of the resonance tube drives the working fluid oscillate in the resonance tube, the working fluid is compressed and expanded and causes temperature oscillation and thermal energy flowing from one end of the stack to the other end. The thermal energy, such as cooling capacity, is finally transferred outward through the heat exchangers on sides of the stacks. The multiple stacks and heat exchangers perform a multiple stage temperature gradient. More thermal energy is transferred, and the working efficiency is improved.

Abstract: A two-stage cryocooler (10) includes an ambient temperature portion (12), a first-stage temperature portion (14), and a second-stage temperature portion (16). The ambient temperature portion includes a surge volume (44) that is coupled to and in communication with the first-stage temperature portion. The surge volume may be coupled to a first-stage interface (36) of the first-stage temperature portion by use of an inertance tube (42). Locating the surge volume in the ambient temperature portion may advantageously reduce size and mass of the first-stage temperature portion. Also, thermal losses may be reduced by maintaining the surge volume at ambient temperature. Space and structural requirements for maintaining the system may be met more easily with the surge volume maintained in the ambient temperature portion of the two-stage cooler. The surge volume may be a separate unit, or may be a plenum or other chamber within an expander in the ambient temperature portion.

Abstract: A refrigeration system especially useful for refrigerating biological samples wherein a cryocooler, such as one employing a pressure wave from a pressure wave generator, is used to generate refrigeration for cooling liquid coolant or purging fluid, which is employed within hollow structures bordering an enclosed space of a storage unit or within the storage space of a storage unit and is subsequently cleaned of contaminants purged from the storage space.

Abstract: According to one embodiment of the present invention, a thermoacoustic device has a complaint enclosure which includes a rigid portion and a compliant portion. The compliant portion includes an oscillating member and a flexure seal with a pair of ends and a flexure body extending between the ends. One of the ends is sealed to the rigid portion and the other end is sealed to the oscillating member. The flexure seal has an average cross-sectional area and an end-to-end equilibrium length. A flexure volume is defined as the product of the average cross-sectional area and the end-to-end equilibrium length. A thermal core is disposed in the complaint enclosure and includes at least a first and a second heat exchanger. A working volume of gaseous working fluid fills the complaint enclosure. The working volume of gaseous working fluid has an equilibrium pressure.

Abstract: A pulse tube refrigerating machine, comprising a pulse tube (11) connected to a regenerator (9) and having a hot end part (11a) being heated, in which a cooling device (30), for cooling the hot side tube wall (11cd) of the pulse tube by cooling medium lower in temperature than the hot side tube wall of the pulse tube, cools the hot side tube wall (11cd) of the pulse tube by coolant flowing from the pressure source (1) of the pulse tube refrigerating machine into the regenerator (9).

Abstract: A regenerative refrigerating apparatus which can increase the speed of cooling and heating a subject to be cooled. The specific constitution of the regenerating type refrigerating apparatus includes a pressure control means 4 having a compressor 4a, a high pressure selector valve 4b, and a low pressure selector valve 4c, an expanding/compressing unit 1 having a room temperature end 1a and a low temperature end 1b, and a regenerating unit 2 having a room temperature end 2a and a low temperature end 2b, carries out heat transfer to a subject to be cooled, and is comprised of a flow path for working gas connecting the low temperature end 1b of the expanding/compressing unit and the low temperature end 2b of the regenerating unit with each other, and simultaneously extending to the subject to be cooled 7.

Abstract: A densifier (10) for simultaneously densifying two cryogenic liquids at different temperatures is provided. The densifier (10) has a thermoacoustic heat engine (20), a resonance tube (18) and a two stage pulse tube refrigerator (40). The thermoacoustic heat engine (20) generates oscillatory acoustical power required to generate net refrigeration power in the two-stage pulse tube refrigerator (40). The first stage (100) densifies a first cryogenic liquid to a first cryogenic temperature, and the second stage (200) densifies a second cryogenic liquid to a second, lower cryogenic temperature. The thermoacoustic heat engine (20) converts thermal energy to the oscillatory acoustical power required to generate net refrigeration in the first (100) and second (200) stages of the pulse tube refrigerator (40). No mechanical energy input is required, and therefore the invented densifier (10) has no moving parts.

Abstract: A piston includes a circumferential groove having a dynamic split seal ring having a flat axially facing surface, a static seal ring having a flat axially facing surface abutting the flat surface of the dynamic seal ring, and a spring mounted within the groove. The spring exerts an axial force on the static seal ring that serves to distribute the axial load with a static seal over the dynamic split seal, thereby preventing shuttling of the split seal within the groove and restricting the leak path of the seal. Preferably, the static seal ring is a polymer and can be an L-ring, a load ring with a flange that abuts the piston body, or flanged designs. In addition, a load ring can be fitted between the L-ring and the spring. The split seal ring has at least one radial spring mounted within the seal ring to create a radial force on the split seal ring. The piston can also include a sleeve that mounts to the piston body, the sleeve forming a wall of the groove.

Abstract: A method for operating a cryocooler which provides opportunity for timely intervention prior to failure thus enhancing the reliability of the provision of the refrigeration wherein contaminant concentration downstream of a compressor but upstream of the cryocooler is monitored and the time rate of change of the contaminant concentration is used to calculate a service time.

Abstract: A MEMS based thermoacoustic cryo-cooler for thermal management of cryogenic electronic devices. The cryogenic cooling system can be integrated directly into a cryogenic electronic device. A vertical comb-drive provides an acoustic source through a driving plate to a resonant tube. By exciting a standing wave within the resonant tube, a temperature difference develops across a stack in the tube, thereby enabling heat exchange between heat exchangers. A tapered resonant tube improves the efficiency of the cooling system, compared with a simple cylinder configuration, leading to reduced harmonics and strong standing waves.

Abstract: A heat pump system (10) including a heat generator (15), a heat engine (26) supplied with heat engine working fluid (18) by the heat generator (15) having a heat engine cylinder chamber (34), a heat engine piston (32), and a heat engine piston rod (35), a preheating chamber (31) employing the heat engine working fluid (18) to heat the heat engine cylinder chamber (34), a compressor (40) driven by the heat engine (26) employing compressor working fluid having a compressor cylinder chamber (46), a compressor piston (44), and a compressor piston rod (47), a spacer (50) separating and joining the heat engine piston rod (35) and the compressor piston rod (47), a sealing assembly (38) associated with the spacer (50) separating the heat engine working fluid (18) and the compressor working fluid, and a valve assembly (60) communicating with the heat engine cylinder chamber (34) and controlling the ingress and egress of heat engine working fluid (18) to the heat engine (26).

Abstract: Equipment for cooling an HTS receive coil (4) in an MRI scanner to a temperature below the transition temperature of the HTS comprises a refrigeration unit such as a Stirling cooler (1) the cold head (2) of which is connected by a non-metallic thermally conductive rod (3) to the receive coil (4).

Abstract: A superconducting magnet apparatus includes superconducting coils in a vacuum vessel. The vacuum vessel is provided with a refrigerator for cooling the superconducting coils. The refrigerator includes a motor drive, displacers, and a cooling cylinder accommodating the displacers such that the displacers may reciprocate therein. The vacuum vessel has a sleeve for accommodating the cooling cylinder while isolating them from its vacuum area, the sleeve having an opening near the wall of the vacuum vessel. A first flange is provided at an opening in the cooling cylinder for inserting the displacers therein. The motor drive is attached to the first flange, with the displacers being inserted therein. The first flange has a cylindrical portion to be inserted in the sleeve to seal the space in the sleeve. The motor drive and the displacers can be removed, while leaving the first flange and the cooling cylinder unremoved.

Abstract: A superconducting machine includes a superconductive device and a vacuum enclosure containing and thermally insulating the superconductive device. A cold-trap is configured to condense gases generated within the vacuum enclosure, and a coolant circulation system is adapted to force flow of a cryogen to and from the superconductive device and the cold-trap. A cryogenic cooling system is configured to cool the cryogen in the coolant circulation system upstream of the superconductive device. A vacuum retention method, for a high-temperature superconductive HTS device, includes applying vacuum to the HTS device to thermally insulate the HTS device, condensing gases generated around the HTS device using a cold-trap, flowing a cryogen to and from the HTS device, and flowing the cryogen to and from the cold-trap.

Abstract: A pulse tube refrigerator system comprises a pulse tube refrigerator and a compressor coupled together via a high pressure line and a low pressure line. Cryogenic fluid is transferred to the PTR via the high pressure line and returned to the compressor via the low pressure line. The system further comprises an acoustic tuning device coupled to the low pressure line between a low pressure output from the PTr and a lower pressure input to the compressor, such that noise and vibration in the PTR system are reduced.

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: In a device for the re-condensation of low-boiling gases evaporating from a liquid gas container having a tubular neck in which a cold head of a cryo-generator is supported, the cold head includes a pulse tube with a heat exchanger and a cold area having an annular projection extending into an annular recess formed in a heat transfer ring mounted in the tubular neck in closely spaced relationship with the walls of the annular recess so as to provide a gas passage therethrough and permitting relative axial movement between the cold head and the liquid gas container.

Abstract: A heat driven acoustic type pulse tube cryocooler has metal knit installed within a driving section cooling a driving gas of an application device using a principle of high temperature superconductivity, and then homogeneously heats the driving gas by way of premixed combustion so that the driving gas generates an acoustic having a predetermined frequency. The orifice installed within a reservoir controls the amount of the driving gas running between the cold reservoir and the pulse tube to constantly maintain a pressure of the cold reservoir. Therefore, the driving gas repeats the process of the compression and expansion centering around the pulse tube, thereby cooling the application device.

Abstract: The performance of a multi-stage inertance pulse tube cryocooler in accordance with an embodiment of the present invention may be enhanced by cooling the inertance tube of one stage placing it in thermal communication with the cool heat exchanger of a preceding stage. Cooling at least one inertance tube of a multi-stage cooler in this invention lowers the viscosity and sound speed of the gas in the inertance tube, thereby improving the cooling power for that subsequent cooling stage, and for the entire device.

Abstract: The Mechanical Freezer of this invention closely approaches an ideal freezer cycle composed of constant temperature compression, expansion, and constant volume heating (load transfer) by using power piston 106 that power input shaft 50 moves up and down and displacers 104 and 105 that are moved by cam 108. When power piston 106 moving up and additional displacer 105 moving down come together, fluid is forced through additional heat sink 41 where it is cooled as it is compressed. When additional displacer 105 and primary displacer 104 come together, fluid is forced through primary heat sink 40 where it is cooled as it is compressed. After compression, the cooled fluid is expanded by power piston 106 along with displacers 104 and 105 moving down. When displacers 104 and 105 then move up, fluid is forced through load 30 and load 30 is cooled.

Abstract: A Stirling refrigeration system (1) comprises two Stirling refrigeration units (4a, 4b) incorporating respective working gas end (WGE) heat exchangers (35a, 35b) and radiators (65a, 65b). Cooling water circulates through a first radiator (65a), a first WGE heat exchanger (35a), a second radiator (65a), a second WGE heat exchanger (35a), and a cooling-water pump (67) in sequence. To facilitate deaeration of the cooling-water circuit at time of feeding cooling water, An air release duct (85) is provided at the maximal point of the cooling-water circuit. An air release valve (79) is formed in the open end of the air release duct (85) so that the air remaining in the cooling-water circuit can be easily released. The Stirling refrigeration system is compact in dimensions.

Abstract: A Stirling engine comprises a first porous body having a large hole diameter, a second porous body having a small hole diameter and a ring for fixing the first porous body and the second porous body in a pressurization chamber inside a gas outlet closer to the pressurization chamber.

Abstract: A refrigeration generation system wherein a frequency modulating mechanical resonator is positioned between a pressure wave generator and a cryocooler and serves to reduce the frequency of the oscillating gas emanating from the pressure wave generator so that it more closely comports with a more efficient operating frequency of the cryocooler.

Abstract: An active balance system is provided for counterbalancing vibrations of an axially reciprocating machine. The balance system includes a support member, a flexure assembly, a counterbalance mass, and a linear motor or an actuator. The support member is configured for attachment to the machine. The flexure assembly includes at least one flat spring having connections along a central portion and an outer peripheral portion. One of the central portion and the outer peripheral portion is fixedly mounted to the support member. The counterbalance mass is fixedly carried by the flexure assembly along another of the central portion and the outer peripheral portion. The linear motor has one of a stator and a mover fixedly mounted to the support member and another of the stator and the mover fixedly mounted to the counterbalance mass. The linear motor is operative to axially reciprocate the counterbalance mass.

Abstract: In a Stirling refrigerator, waste heat rejected from the heat rejecter of a Stirling refrigerating device is transferred by way of dew prevention heat pipes to heat the open side of the refrigerator. This makes it possible to prevent condensation of moisture on the open side of the refrigerator, where dew tends to collect as a door is opened or closed or in other situations, in an effective and energy-saving manner without using a heater, and thereby alleviate the load on the heat-rejecting heat exchanger.

Abstract: In an apparatus and a method for controlling operation of a compressor, by removing deviation generated by resistance and inductance and removing an error in a stroke estimation value of a compressor, operation of the compressor can be accurately controlled. The apparatus includes a counter electromotive force detector for detecting a counter electromotive force generated at a motor of a compressor. A stroke calculator calculates a stroke estimation value of the compressor on the basis of the counter electromotive force, and a stroke controller controls a stroke of the compressor by varying a voltage applied to the motor on the basis of the calculated stroke estimation value and a stroke reference value.

Abstract: An apparatus for extracting cooling power from helium flowing through a cooling system regenerator includes a heat exchanger disposed within the regenerator capable of extracting cooling power from the helium and a thermal link coupled to the heat exchanger for thermally coupling the heat exchanger with a component. A method of extracting cooling power from helium in a regenerator includes flowing the helium through a first portion of the regenerator, flowing the helium through a heat exchanger disposed between the first portion and a second portion of the regenerator to transfer heat from the heat exchanger to the helium, and transferring heat from a component via a thermal link to the heat exchanger.

Abstract: A thermoacoustic engine-generator that converts waste heat into electrical power. Thermal energy is converted to useful work via temperature-pressure amplification of periodic acoustic traveling waves in a compressible working fluid which cause the armature of a linear alternator to reciprocate and produce alternating current electrical energy. An external oscillator initiates reciprocating motion in the armature of a linear alternator. The armature is a combination fluid pump and fluid motor as well as the induction armature of a linear alternator. The pump end of the armature generates an acoustic traveling wave with each cycle of the armature. The traveling wave enters a waveguide-heat exchanger and is amplified in temperature, pressure and propagation velocity by thermal conduction of energy through the wall of the waveguide.

Abstract: A Stirling refrigerator has an outer yoke assembly (11) provided as an outer yoke constituting a linear motor (16) and has a piston-support-spring support member (14A) and a displacer-support-spring support member (14B) that are supported by the outer yoke assembly (11) for fixing a piston support spring (5) and a displacer support spring (6) respectively. By the above-described structure, it is achieved to facilitate handling, in assembly of mass production, of a bobbin/coil and an outer yoke of an outer yoke body constituting the linear motor and reduce the size of the outer shape of a casing.

Abstract: The present invention provides a method of sensorless control of a linear reciprocating electrodynamic machine used for driving a thermoacoustic device, and/or a similar frequency dependent load. Sensorless control is accomplished by estimating the state of predetermined performance parameters at the linear machine through the use of a system model. Thereafter, the method comprises providing a control means operative to obtain the estimated performance parameters and cause manipulation of at least one input parameter to the linear machine such that desired performance parameters are obtained in view of the estimated performance parameters.

Abstract: An operation control apparatus and method of a linear compressor are disclosed. The operation control apparatus includes: an ambient temperature sensor unit for sensing a temperature around a refrigerator; a second microcomputer for outputting a control signal according to a temperature statue of a temperatures sensing unit for sensing an inner temperature of the refrigerator; a load driving unit for receiving an ON/OFF control signal for driving a linear compressor from the second microcomputer and outputting a drive signal to the linear compressor; a relay switched by the driving signal and supplying an AC power to a motor of the linear compressor; and a power supply unit for converting the AC power into a DC power and supplying power to each unit inside the linear compressor.

Abstract: A free-piston type Stirling engine used for producing cold heat with the vibration center position of a piston accurately kept. A first space is formed on one side of a piston, and a second space is formed on the opposite side to spread up to a portion adjacent to a cylinder's side wall. A piston is provided with a vibration-direction first groove extending up to the first space and a circumferential-direction second groove, and a cylinder is provided with a hole penetrating the side wall thereof. The second groove of the piston, when coupled with the cylinder's hole during a piston vibration process, allows the first space to communicate with the second space. Accordingly, a short-time communication between the first and second spaces will balance pressures in the two spaces against each other to keep the vibration center position of the piston accurately.

Abstract: Systems and methods for manipulating acoustic energy are presented. In some embodiments, a combustion zone provides heat to a regenerator using a mean flow of compressible fluid. In other embodiments, a thermoacoustic driver is concentrically disposed within a shell to permit radial heat transfer from the thermoacoustic driver to compressible fluid within the shell, thereby preheating the compressible fluid within the shell. In other embodiments, burning of a combustible mixture within the combustion zone is pulsed in phase with the acoustic pressure oscillations to increase acoustic power output.