Abstract: A cryogenic refrigerator includes a cylinder, a displacer configured to be moved back and forth in the cylinder by a drive unit, an inlet valve configured to be opened in supplying a refrigerant gas into the cylinder, an exhaust valve configured to be opened in exhausting the refrigerant gas from the cylinder, and an expansion space formed in the cylinder and configured to generate a cooling by expanding the refrigerant gas caused by back and forth movement of the displacer. A moving speed of the displacer in the vicinity of a bottom dead center is set to be faster than the moving speed of the displacer in the vicinity of a top dead center.

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 helium-cooling type regenerator includes first and second storage spaces. The first storage space is disposed in a region on a high-temperature side, and accommodates the regenerator material whose pressure is P1. The second storage space is disposed in a region on a low-temperature side, and accommodates the regenerator material whose pressure is P2, which is less than P1. A specific heat in the case where a pressure of the regenerator material accommodated in the first storage space is P2 is less than that in the case where the pressure of the regenerator material is P1, and a specific heat in the case where a pressure of the regenerator material accommodated in the second storage space is P1 is less than that in the case where the pressure of the regenerator material is P2.

Abstract: A cryogenic refrigerator includes a refrigerator body configured to produce cold temperatures by expanding a refrigerant gas; a compressor connected to a first pipe for feeding the refrigerant gas of a first pressure to the refrigerator body, and connected to a second pipe for collecting the refrigerant gas of a second pressure lower than the first pressure from the refrigerator body; a buffer tank configured to store the refrigerant gas; a first valve provided in a first connecting pipe connecting the buffer tank and the refrigerator body; a second valve provided in a second connecting pipe connecting the buffer tank and the first pipe; and a third valve provided in a third connecting pipe connecting the buffer tank and the second pipe.

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 for installation on a stationary component, an expander for installation on a rotating component, and a rotary joint fluidly coupling the compressor with the expander. The rotary joint includes: a rotor fixed to the rotating component and coaxial with its rotational axis; a stator disposed adjacent to the rotor to form a clearance between the rotor and the stator, and fixed to the stationary component; a first high-pressure flowpath and a second high-pressure flowpath, extending between the rotor and stator through the clearance, and a working-gas sealing area dividing the clearance into a first high-pressure section communicating with the first high-pressure flowpath, and into a second high-pressure section communicating with the second high-pressure flowpath.

Abstract: A regenerative refrigerator includes an expander which includes a regenerator including a regenerative material and an expansion space for expanding a refrigerant gas flowing in the regenerator, the regenerator being configured such that a temperature profile at a predetermined temperature range in the regenerator is selectively higher than a case when lead is used as the regenerative material.

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: In a cryocooler for developing coldness of 4 K or lower by expanding helium, an expander expands high-pressure helium. A compressor compresses low-pressure helium returned from the expander, to generate high-pressure helium, and supplies the high-pressure helium to the expander. When helium temperature in the expander is 2.17 K or lower, the pressure of the low-pressure helium is equal to or higher than pressure given by a curve, in a helium state diagram in which the horizontal axis is temperature and the vertical axis is pressure, along which helium's volumetric thermal expansion coefficient is 0.

Abstract: In a cryogenic refrigerator, a displacer defines an internal space, and circulates a working fluid in the internal space. A cylinder houses the displacer such as to enable it to reciprocate, and, at an interval from the bottom side of the displacer, forms an expansion space for the working fluid. A cooling stage is provided along an outer circumferential and bottom portion of the cylinder, in a location corresponding to the expansion space. A heat exchanger is arranged inside the expansion space and is thermally connected to the cooling stage. An end portion of the displacer on its expansion-space side has an opening that serves as an entry/exit port between the internal space and the expansion space for the working fluid. A working-fluid flow channel connects the internal space and the expansion space via the heat exchanger.

Abstract: In a pulse tube refrigerator, a gas flow passage is connected to a high-temperature end of a low-temperature side pulse tube and a compressor, such that a working gas flows in the gas flow passage. The gas flow passage includes: a first flow passage connected to the high-temperature end of the low-temperature side pulse tube; a second flow passage connected to the compressor and having an outlet facing an outlet of the first flow passage; and a housing that gastightly accommodates the outlet of the first flow passage and the outlet of the second flow passage. The housing has a gastight space communicating with the outlet of the first flow passage and the outlet of the second flow passage, the gastight space located on a side of the low-temperature side pulse tube with respect to the outlet of the first flow passage.

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 two-stage GM cryogenic refrigerator includes a displacer having a low-temperature side and a high-temperature side and a motor configured to drive the displacer. The motor is configured to be rotatable forward in cooling and backward in increasing a temperature. The cryogenic refrigerator further includes a resin provided on an outer circumferential surface of the displacer. A thickness of the resin is thinner on the high-temperature side than on the low-temperature side.

Abstract: A double inlet type pulse tube refrigerator includes a regenerator having a high temperature end and a low temperature end; a pulse tube having a high temperature end and a low temperature end connected to the low temperature end of the regenerator; a compressor having a high pressure supplying side and low pressure receiving side for a coolant, a bypass pipe having a double inlet valve, the bypass pipe being configured to connect the high temperature end of the pulse tube and the high temperature end of the regenerator; a buffer tank connected to the high temperature end of the pulse tube via a first pipe having a first flow path resistance member; and a second pipe having a second flow path resistance member including a third opening and closing valve.

Abstract: In a cryogenic refrigerator, a displacer has an internal space in which refrigerant gas flows. A cylinder houses the displacer to enable the displacer to perform reciprocating movement and forms an expansion space of the refrigerant gas between the cylinder and a bottom surface of the displacer. The displacer supplies the refrigerant gas to the expansion space during movement inside the cylinder from a bottom dead center to a top dead center. The displacer collects the refrigerant gas from the expansion space during movement inside the cylinder from the top dead center to the bottom dead center. A flow path resistance between the displacer and the expansion space is lower when the displacer is at the bottom dead center than when the displacer is at the top dead center.

Abstract: A regenerator of a regenerative refrigerator includes: a magnetic regenerator material used for cold storage; and a container that accommodates the magnetic regenerator material. A part of the container that accommodates the magnetic regenerator material includes: a first region that includes a temperature range in which a specific heat of the magnetic regenerator material reaches maximum during an operation of the regenerative refrigerator, and a second region that is in a temperature range different from that of the first region. A cross sectional area of a part of the first region that accommodates the magnetic regenerator material is smaller than a cross sectional area of a part of the second region that accommodates the magnetic regenerator material.

Abstract: A pulse tube refrigerator includes a first pulse tube; a first regenerator connected to the first pulse tube; a compressor configured to compress the coolant gas; a first supply side valve; a first filter provided between a supply side of the first supply side valve and the high temperature end of the first regenerator; a first suction side valve connected to the first filter via a first joint point; a first self seal joint provided between the supply side of the compressor and a suction side of the first supply side valve; a second self seal joint provided between a supply side of the first suction side valve and the suction side of the compressor; and a third self seal joint provided between a first regenerator side of the first filter and the high temperature end of the first regenerator.

Abstract: In a cryogenic refrigerator, a displacer includes a low temperature end and a high temperature end. A cylinder accommodates the displacer to be reciprocated in a longitudinal direction, and forms an expansion space which is an expansion space of a refrigerant gas between the low temperature end of the second displacer and the cylinder. The damper portion is disposed to be adjacent to the expansion space and communicates with the expansion space. A volume of the damper portion is 30% or less of a volume of the 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 pulse tube refrigerator, a first pulse tube has a low-temperature end, and a high-temperature end connected to a compressor. A first regenerator has a low-temperature end connected to the low-temperature end of the first pulse tube, and a high-temperature end connected to the compressor. A second pulse tube has a high-temperature end connected to the compressor, and a low-temperature end having a lower temperature than the low-temperature end of the first pulse tube. A second regenerator has a high-temperature end, and a low-temperature end connected to the low-temperature end of the second pulse tube, and is arranged side by side with the second pulse tube. The second pulse tube includes a narrowed portion nearer a low-temperature end side than a position corresponding to the high-temperature end of the second regenerator.