A compressor unit of a cryogenic refrigeration device includes a compression chamber that is connectable via a transfer line to an expander unit. A piston is configured to alternately compress and decompress a gaseous working agent in the compression chamber. An electromagnetic actuator includes a stator assembly with a driving coil that is wound about the longitudinal axis and that is enclosed within a toroidal back iron except for a coaxial cylindrical gap in a radially outward facing surface. A movable assembly connected to the piston includes two movable permanent magnets separated by a ferromagnetic spacer radially exterior to the stator assembly. The movable magnets are magnetized parallel to the longitudinal axis and opposite to one another such that an alternating electrical current in the driving coil causes the movable assembly to parallel to the longitudinal axis to periodically drive the piston into and out of the compression chamber.

A circulating loop for transporting refrigeration to a remote location is connected serially between a Gifford-McMahon (GM) or GM type Pulse Tube cold head and the compressor. Either high pressure gas from the compressor can flow through the remote heat station before returning to the cold head or low pressure gas can flow from the cold head to the remote heat station before returning to the compressor. A first fraction of gas, which may include all of the gas at ambient temperature, enters a counter-flow heat exchanger, is cooled by the cold head, flows to the remote load, and then returns to ambient temperature as it flows through the counter-flow heat exchanger. The high or low pressure line may have a circulation control valve that diverts a second fraction of gas to flow directly between the cold head and compressor. A controller adjusts the circulation control valve to optimize the cooling of the load.

A compressor unit of a refrigeration device includes a compression chamber. A piston is configured to be moved back and forth along an axis to alternately compress and decompress a gas in the chamber. An electromagnetic actuator is configured to drive the piston and includes a stator assembly with a driving coil that is coaxial with the axis and two permanent ring magnets that are radially magnetized identically to one another in a plane that is perpendicular to the axis. The ring magnets are located on opposite sides of the driving coil along the axis. A ferromagnetic shaft is elongated parallel to the axis and connected to the piston. When an alternating electrical current flows through the coil, the shaft is magnetized such that the shaft is alternately attracted to one of the ring magnets and repelled by the other to drive the piston back and forth.

A heat station for a GM or Stirling cycle expander provides a versatile, efficient, and cost effective means of transferring heat from a remote load at cryogenic temperatures that is cooled by a circulating cryogen to the gas in a GM or Stirling cycle expander as the gas flows between a regenerator and a displaced volume. The heat exchanger includes a shell that has external and internal fins that are thermally connected, are aligned parallel to the axis of the shell, and are enclosed in a housing having a single port on the bottom of the housing.

Provided is a linear compressor. Provided is a linear compressor. The linear compressor includes a shell defining an internal space, a compressor body disposed in the internal space, and a passage guide disposed between the shell and the compressor body. The passage guide may include a first guide part extending along an inner surface of the shell in an axial direction and a second guide part extending from the first guide part to the compressor body in a radial direction.

A free piston Stirling refrigerator of the present invention has a cylinder provided inside a casing; a piston and a displacer that are provided in a way such that they are capable of reciprocating inside the cylinder; a linear motor for reciprocating the piston; and a control unit for controlling the operation of the linear motor. Particularly, the control unit has an inverter circuit for generating an alternating current with a given frequency and then supplying the alternating current to the linear motor; a current detection circuit for detecting the current outputted from the inverter circuit; and a control circuit for controlling the output from the inverter circuit based on a turbulence in the current detected by the current detection circuit. Thus, collisions between the piston and the displacer (i.e. hitting) can be restricted through an inexpensive configuration and a simple control.

A cryocooler includes a second-stage cooling stage, a second cylinder which includes the second-stage cooling stage on a terminal of the second-stage cylinder, a second-stage displacer which includes a magnetic regenerator material and is accommodated in the second-stage cylinder so as to be able to reciprocate in the second-stage cylinder, and a tubular magnetic shield which is installed on the second-stage cooling stage and extends along the second-stage cylinder outside the second-stage cylinder. The magnetic shield is formed of a normal conductor and a product of an electrical conductivity in a temperature range of 10 K (Kelvin) or less and a thickness of the tubular magnetic shield is 60 MS (Mega-Siemens) to 1980 MS.

A cryogenic refrigerator includes a displacer that is reciprocably mounted within a cylinder; a spool valve that is connected to the compressor and performs switching between an intake mode where a high-pressure refrigerant gas is supplied from the compressor to the cylinder and an exhaust mode where a low-pressure refrigerant gas within the cylinder is made to flow back to the compressor; and a drive unit that drives the spool valve. The spool valve has a valve body, and a drive rod that moves relative to the valve body and is integrated with the spool. The drive unit performs driving so that the magnitude of a speed when the drive rod moves from a top dead center to a bottom dead center is different from the magnitude of a speed when the drive rod moves from the bottom dead center to the top dead center, at the same displacement position.

The present disclosure relates to a linear compressor. The linear compressor according to an aspect of the present disclosure includes a shell, a cylinder, a piston, and a muffler. Also, an internal space in which at least a portion of the muffler is inserted is formed in the piston, and the muffler is disposed in contact with the inner wall of the piston forming the internal space.

A cryocooler includes a motion conversion mechanism that converts rotating motion output by a motor into linear reciprocating motion of a displacer and includes a first component and a second component slidably connected to each other, a measuring instrument that is connected to the motor to output time-series data indicating power consumption of the motor or a current flowing through the motor, and a processing unit that detects abrasion of a sliding surface between a first component and a second component of the motion conversion mechanism on the basis of section data including an intake start timing or an exhaust start timing in the time-series data.