The application relates to a cryogenic machine of the regenerative type, comprising: a pressure oscillator, at least one cold finger (20) in fluid connection with the pressure oscillator,

wherein the pressure oscillator comprises a centrifugal compressor (1) and a fluid distribution member (12) configured to alternately distribute high-pressure and low-pressure working fluid from the centrifugal compressor into said cold finger.

A Gifford-McMahon (GM) type double-inlet pulse tube system providing cooling at cryogenic temperatures is provided. The system has a co-axial double-inlet valve that includes a base having an adjustable port, a fixed needle partially engaged in one end of the adjustable port, an adjustable needle partially engaged in another end of said adjustable port, and a body for housing the base, the fixed needle and the adjustable needle. The base is configured to be adjustable along an axial direction. The adjustable needle is arranged co-axially with the fixed needle. The adjustable port and the adjustable needle are configured to control an alternating current (AC) flow and a direct current (DC) flow between the stem port and the end port and to produce the DC flow in either direction between the stem port and the end port.

A rotary valve mechanism includes a valve stator having a stator recessed portion and a valve rotor having a rotor recessed portion. The rotor recessed portion is formed in the valve rotor such that a rotor-recessed-portion front edge line passes through a stator-recessed-portion front edge line and the rotor recessed portion fluidally communicates with the stator recessed portion at a first phase of rotary-valve-mechanism rotation, and a rotor-recessed-portion rear edge line passes through a stator-recessed-portion rear edge line and the rotor recessed portion is fluidally separated from the stator recessed portion at a second phase thereof, and a shape of the rotor-recessed-portion front edge line coincides with a shape of the stator-recessed-portion front edge line such that the rotor-recessed-portion front edge line overlaps the stator-recessed-portion front edge line at the first phase.

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.

A rotary valve mechanism of a cryocooler includes a valve rotor and a valve stator. A rotor recessed portion is formed such that the rotor recessed portion fluidally communicates with a stator recessed portion at a first opening degree at a second phase of a valve rotation. The valve rotor includes a first rotor communication groove and/or a second rotor communication groove formed in the valve rotor such that the rotor recessed portion fluidally communicates with the stator recessed portion at an opening degree which is smaller than the first opening degree at a first phase preceding the second phase, and/or the valve stator includes a stator communication path formed in the valve stator such that the rotor recessed portion fluidally communicates with the stator recessed portion at an opening degree which is smaller than the first opening degree at the first phase preceding the second phase.

A Gifford-McMahon (GM) type double-inlet pulse tube system providing cooling at cryogenic temperatures is provided. The system has a co-axial double-inlet valve that includes a base having an adjustable port, a fixed needle partially engaged in one end of the adjustable port, an adjustable needle partially engaged in another end of said adjustable port, and a body for housing the base, the fixed needle and the adjustable needle. The base is configured to be adjustable along an axial direction. The adjustable needle is arranged co-axially with the fixed needle. The adjustable port and the adjustable needle are configured to control an alternating current (AC) flow and a direct current (DC) flow between the stem port and the end port and to produce the DC flow in either direction between the stem port and the end port.

A cryocooler includes a cold head, a valve unit which includes a rotary valve configured to periodically switch a pressure of a working gas in the cold head between a first high pressure and a second high pressure lower than the first high pressure and a valve motor configured to rotate the rotary valve, the valve unit having a rotation angle range in which the rotary valve seals the working gas having the second high pressure in the cold head, a cryocooler control unit configured to control the valve motor, a cryocooler stop instruction unit configured to output a cryocooler stop instruction signal to the cryocooler control unit, and a valve stop timing control unit configured to control the valve motor to stop the rotary valve in the rotation angle range, according to the cryocooler stop instruction signal.

A rotary valve unit includes a rotary valve and a reversible motor. The rotary valve operates according to a cooling valve timing for cooling a pulse tube cryocooler when the reversible motor rotates in a forward direction and is operated according to a heating valve timing for heating the pulse tube cryocooler when the reversible motor rotates in a backward direction. The cooling valve timing is designed to generate a working gas pressure oscillation in a pulse tube and apply a first phase delay to a working gas displacement oscillation in the pulse tube with respect to the working gas pressure oscillation. The heating valve timing is designed to generate the working gas pressure oscillation in the pulse tube and apply a second different phase delay to the working gas displacement oscillation in the pulse tube with respect to the working gas pressure oscillation.

A rotary valve of a cryocooler includes a valve stator, a valve rotor, a rotation member that rotates the valve rotor around an axis with respect to the valve stator, and a rotor holder connected to the valve rotor so as to rotate around an axis together with the valve rotor, and forming a low pressure section having a pressure lower than an ambient pressure between the valve rotor and the rotor holder so as to reduce an axial force of pressing the valve rotor against the valve stator. The rotation member is connected to the rotor holder so as to rotate the valve rotor around the axis via the rotor holder. The rotor holder is disposed between the rotation member and the valve rotor in an axial direction, and is movable in the axial direction with respect to the rotation member.

A rotary valve mechanism of a cryocooler includes a valve rotor and a valve stator. A rotor recessed portion is formed such that the rotor recessed portion fluidally communicates with a stator recessed portion at a first opening degree at a second phase of a valve rotation. The valve rotor includes a first rotor communication groove and/or a second rotor communication groove formed in the valve rotor such that the rotor recessed portion fluidally communicates with the stator recessed portion at an opening degree which is smaller than the first opening degree at a first phase preceding the second phase, and/or the valve stator includes a stator communication path formed in the valve stator such that the rotor recessed portion fluidally communicates with the stator recessed portion at an opening degree which is smaller than the first opening degree at the first phase preceding the second phase.