Abstract: 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.

Abstract: 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.

Abstract: In a cryocooler, a displacer includes an internal space, and a working gas flows through the internal space. A cylinder reciprocally accommodates the displacer, and an expansion space for the working gas is formed between the cylinder and a bottom portion of the displacer. A plurality of annular protruding portions are provided on a bottom surface of the expansion space such as to form a multiplex structure. A plurality of annular recessed portions are provided on the bottom portion of the displacer such as to receive the plurality of annular protruding portions.

Abstract: A rotary valve mechanism includes a stator valve member furnished with one of either a dome-shaped high-pressure recess area made of a polymer or a high-pressure flow path made of metal, and a rotor valve member furnished with the other of either the dome-shaped high-pressure recess area made of a polymer or the high-pressure flow path made of metal, and seals a high-pressure region being the high-pressure flow path communicated with the dome-shaped high-pressure recess area and is disposed adjoining the stator valve member such as to isolate the high-pressure region from its low-pressure surrounding environs.

Abstract: A cryogenic refrigerator includes a compressor, an expansion space where a high-pressure working gas discharged from a discharge side of the compressor is caused to expand, and a valve. The valve includes a first member including a first channel connecting to the discharge side and a second member including a second channel connecting to the expansion space. The first and second members are configured to rotate relative to and in contact with each other to connect or disconnect the first and second channels. In a plane where the first and second members are in contact, a first distance that is a distance of closest approach between the first channel and a valve circumference defined by a circumference of one of the first and second members having a smaller diameter is greater than a second distance that is a distance of closest approach between the second channel and the valve circumference.

Abstract: A GM cryocooler is furnished with: a first cold head including a first displacer and a first cylinder; a second cold head including a second displacer and a second cylinder and being disposed opposing the first cold head; a common drive mechanism for driving axial reciprocation of the first displacer and the second displacer; and a working gas circuit for generating between the first cold head and the second cold head a pressure differential that assists the common drive mechanism.

Abstract: A cryocooler includes a displacer, a cylinder in which the displacer is accommodated, a Scotch yoke mechanism which drives the displacer, and a housing in which the Scotch yoke mechanism is accommodated. The Scotch yoke mechanism includes a crank, a yoke plate, a second drive shaft, and a first drive shaft. The housing may include a drive mechanism accommodation chamber in which the crank and the yoke plate are accommodated, a first assist chamber in which a distal end of the first drive shaft is accommodated, and a second assist chamber which is provided between the drive mechanism accommodation chamber and a gas chamber or between the drive mechanism accommodation chamber and the first assist chamber. The first assist chamber and the second assist chamber can be adjusted to a higher pressure than the pressure in the drive mechanism accommodation chamber.

Abstract: A disclosed device cryogenic refrigerator includes a first stage displacer; a first stage cylinder configured to form a first expansion space between the first stage cylinder and the first stage displacer; a second stage displacer connected to the first stage displacer; and a second stage cylinder configured to form a second expansion space between the second stage cylinder and the second stage displacer, wherein the second stage displacer includes a helical groove formed on an outer peripheral surface of the second stage displacer so as to helically extend from the second expansion space, a flow resistor communicating with a side of the first stage displacer in the helical groove, and a flow path connecting the flow resistor to a side of the first expansion space, wherein the flow resistor is always positioned on a side of the second expansion space relative to the first expansion space.

Abstract: A disclosed device cryogenic refrigerator includes a first stage displacer; a first stage cylinder configured to form a first expansion space between the first stage cylinder and the first stage displacer; a second stage displacer connected to the first stage displacer; and a second stage cylinder configured to form a second expansion space between the second stage cylinder and the second stage displacer, wherein a helical groove is formed on an outer peripheral surface of the second stage displacer so as to helically extend from a side of the second expansion space toward the first stage displacer, wherein the second stage cylinder includes a first flow resistor communicating with a side of the first stage displacer in the helical groove, and a buffer portion communicating with a side of the first stage displacer in the first flow resistor.

Abstract: A cryogenic refrigerator includes a compressor that compresses a working gas; a displacer to which the working gas compressed by the compressor is supplied; a drive mechanism that includes a drive shaft and is configured to drive the displacer; a motor that drives the drive mechanism; a housing that accommodates the drive mechanism; a valve mechanism that adjusts a pressure of the working gas supplied to the displacer; a pipe that supplies the working gas from the compressor to the valve mechanism; and a branch pipe that branches out from the supply pipe and is connected to a space formed between the drive shaft and the housing.

Abstract: A cryogenic refrigerator includes a compressor having a return end and a suction end that selectively connects to an expansion space, a housing having an assist space that communicates to the return end, a cylinder having one end connected to the housing and another end connected to the expansion space, a displacer that undergoes a reciprocating motion inside the cylinder, and tolerates flow of a working gas to and from the expansion space, and a drive shaft that is accommodated within the housing and drives the displacer. The drive shaft includes first and second parts having different cross sectional areas, sealed and supported by first and second seals, respectively. An end of the first part opposes the housing to form the assist space, and an end of the second part connects to the displacer.

Abstract: In a cryogenic refrigerator, a valve switches between a flow passage of a low-pressure refrigerant gas and a flow passage of a high-pressure refrigerant gas. A motor drives the valve. The motor includes a rotor and a stator, the rotor located radially inward of the stator. A casing gastightly houses the rotor and the stator. The stator includes a back yoke and a magnetic member that acts as a magnetic path of an external magnetic field generated outside of the casing, the magnetic member located radially outward of and spaced apart from the back yoke. The magnetic member is gastightly housed in the casing.

Abstract: A disclosed cryogenic refrigerator includes a first stage displacer; a first stage cylinder configured to form a first expansion between the first stage cylinder and the first stage displacer; a second stage displacer connected to the first stage displacer; and a second stage cylinder configured to form a second expansion space between the second stage cylinder and the second stage displacer, wherein a helical groove is formed on an outer peripheral surface of the second stage displacer so as to helically extend from a side of the second expansion space toward the first stage displacer, the helical groove communicates with the first expansion space, and a cross-sectional area of the helical groove becomes smaller from a side of the second expansion space to a side of the first expansion space.

Abstract: A regenerative refrigerator includes a cylinder configured to cause a refrigerant gas to adiabatically expand; and a regenerator tube connected to the cylinder and including a partitioning member. The partitioning member partitions an internal space of the regenerator tube into a first space in which the refrigerant gas flows and a second space filled with a regenerator material formed of gas. The regenerator tube is configured to accumulate, in the regenerator material, cold generated in the cylinder with adiabatic expansion of the refrigerant gas. The area of exposure of the partitioning member to the second space is greater than the area of exposure of the partitioning member to the first space.

Abstract: In a cryogenic refrigerator, a scotch yoke mechanism includes an eccentric rotating body and a yoke plate that reciprocates by rotation of the eccentric rotating body. A displacer is connected to a yoke plate so as to reciprocate together with the yoke plate. A cylinder houses a displacer, and an expansion space for refrigerant gas is formed in a space with the displacer. An airtight container is provided on a high-temperature side of the cylinder and includes a housing space housing a scotch yoke mechanism and receive the refrigerant gas discharged from the expansion space. The airtight container includes a supporting unit that supports a side portion of the yoke plate so as to restrict tilting of the yoke plate around a rotary shaft of the eccentric rotating body.

Abstract: A cryogenic refrigerator includes a compressor, an expansion space where a high-pressure working gas discharged from a discharge side of the compressor is caused to expand, and a valve. The valve includes a first member including a first channel connecting to the discharge side and a second member including a second channel connecting to the expansion space. The first and second members are configured to rotate relative to and in contact with each other to connect or disconnect the first and second channels. In a plane where the first and second members are in contact, a first distance that is a distance of closest approach between the first channel and a valve circumference defined by a circumference of one of the first and second members having a smaller diameter is greater than a second distance that is a distance of closest approach between the second channel and the valve circumference.

Abstract: A cryogenic refrigerator includes a compressor having a return end and a suction end that selectively connects to an expansion space, a housing having an assist space that communicates to the return end, a cylinder having one end connected to the housing and another end connected to the expansion space, a displacer that undergoes a reciprocating motion inside the cylinder, and tolerates flow of a working gas to and from the expansion space, and a drive shaft that is accommodated within the housing and drives the displacer. The drive shaft includes first and second parts having different cross sectional areas, sealed and supported by first and second seals, respectively. An end of the first part opposes the housing to form the assist space, and an end of the second part connects to the displacer.

Abstract: A cryogenic refrigerator includes a compressor that compresses a working gas; an expansion chamber where the working gas compressed by the compressor expands and generates cooling; a valve mechanism including a stator valve and a rotor valve, which rotates with respect to the stator valve; and a forcing mechanism that applies a force to one of the rotor valve or the stator valve toward the other one of the rotor valve or the stator valve. The valve mechanism is configured to switch a flow of the working gas between the compressor and the expansion chamber as the rotor valve rotates. The forcing mechanism is arranged such that the center of the force applied by the forcing mechanism deviates from the center of the valve mechanism.

Abstract: A cryogenic refrigerator includes a compressor that compresses a working gas; a displacer to which the working gas compressed by the compressor is supplied; a drive mechanism that includes a drive shaft and is configured to drive the displacer; a motor that drives the drive mechanism; a housing that accommodates the drive mechanism; a valve mechanism that adjusts a pressure of the working gas supplied to the displacer; a pipe that supplies the working gas from the compressor to the valve mechanism; and a branch pipe that branches out from the supply pipe and is connected to a space formed between the drive shaft and the housing.

Abstract: 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.