A pulse tube cryocooler includes a pulse tube that includes a tube inner space, and an integral flow straightener that includes a flow straightening layer disposed to face the tube inner space so as to straighten a refrigerant gas flow from the tube inner space or into the tube inner space and a heat exchange layer formed integrally with the flow straightening layer outside the flow straightening layer with respect to the tube inner space so as to exchange heat with the refrigerant gas flow by contact with the refrigerant gas flow and is disposed at a low-temperature end and/or a high-temperature end of the pulse tube. The flow straightening layer includes a plurality of protrusions that protrude from the heat exchange layer toward the tube inner space.

A GM cryocooler includes a compressor having a compressor discharge port and a compressor suction port, a displacer capable of reciprocating in an axial direction, a displacer cylinder accommodating the displacer, a drive piston connected to the displacer so as to drive the displacer in the axial direction, a drive chamber in which the drive piston is driven, a main pressure switching valve configured to alternately connect the displacer cylinder to the compressor discharge port and the compressor suction port, an auxiliary pressure switching valve configured to alternately connect the drive chamber to the compressor discharge port and the compressor suction port, and a buffer volume connected between the auxiliary pressure switching valve and the compressor.

A cryocooler includes a displacer that includes a lid portion and a main body portion, a displacer drive shaft that includes a collar portion held between the lid portion and the main body portion, and a buffer that is disposed in a clearance between the collar portion and the lid portion or between the collar portion and the main body portion and includes a soft material and a hard material disposed on an opposite side to the collar portion with respect to the soft material.

A GM cryocooler includes a displacer that is reciprocatable in an axial direction; a displacer cylinder that houses the displacer; a drive piston that is coupled to the displacer so as to drive the displacer in the axial direction; and a piston cylinder that houses the drive piston and that includes a drive chamber of which a pressure is controlled to drive the drive piston, and a gas spring chamber which is airtightly formed with respect to the displacer cylinder and is partitioned from the drive chamber by the drive piston.

A cryocooler includes a displacer that includes a lid portion and a main body portion, a displacer drive shaft that includes a collar portion held between the lid portion and the main body portion, and a buffer that is disposed in a clearance between the collar portion and the lid portion or between the collar portion and the main body portion and includes a soft material and a hard material disposed on an opposite side to the collar portion with respect to the soft material.

A pulse tube cryocooler includes a pulse tube that includes a tube inner space, and an integral flow straightener that includes a flow straightening layer disposed to face the tube inner space so as to straighten a refrigerant gas flow from the tube inner space or into the tube inner space and a heat exchange layer formed integrally with the flow straightening layer outside the flow straightening layer with respect to the tube inner space so as to exchange heat with the refrigerant gas flow by contact with the refrigerant gas flow and is disposed at a low-temperature end and/or a high-temperature end of the pulse tube. The flow straightening layer includes a plurality of protrusions that protrude from the heat exchange layer toward the tube inner space.

A GM cryocooler includes a compressor having a compressor discharge port and a compressor suction port, a displacer capable of reciprocating in an axial direction, a displacer cylinder accommodating the displacer, a drive piston connected to the displacer so as to drive the displacer in the axial direction, a drive chamber in which the drive piston is driven, a main pressure switching valve configured to alternately connect the displacer cylinder to the compressor discharge port and the compressor suction port, an auxiliary pressure switching valve configured to alternately connect the drive chamber to the compressor discharge port and the compressor suction port, and a buffer volume connected between the auxiliary pressure switching valve and the compressor.

A GM cryocooler includes a displacer that is reciprocatable in an axial direction; a displacer cylinder that houses the displacer; a drive piston that is coupled to the displacer so as to drive the displacer in the axial direction; and a piston cylinder that houses the drive piston and that includes a drive chamber of which a pressure is controlled to drive the drive piston, and a gas spring chamber which is airtightly formed with respect to the displacer cylinder and is partitioned from the drive chamber by the drive piston.

A Stirling-type pulse tube refrigerator includes: a regenerator that has a low temperature end and high temperature end; a pulse tube that is arranged coaxially with the regenerator, and that is connected to the regenerator so as to enable working gas to circulate therebetween; a low temperature heat exchanger that is disposed in the low temperature end of the regenerator, and that has a gas flow passage serving as a flow passage for the working gas; and a flow straightener that is disposed in an end portion, on a side close to the low temperature heat exchanger, out of end portions of the pulse tube. The gas flow passage and the flow straightener are spaced away from each other, and a length of a connecting passage connecting the gas flow passage and the flow straightener is equal to or shorter than 10% of a length of the pulse tube.

A first regenerator of a regenerative refrigerator includes a first regenerator member and a first cylinder accommodating the first regenerator member. A second regenerator includes a second regenerator member and a second cylinder accommodating the second regenerator member and may be connected to a low temperature end of the first regenerator. A gas pipe guides a coolant gas discharged from the first regenerator to a portion in the middle of the second regenerator. The gas pipe may include a plurality of gas relief holes in the middle of the gas pipe.