A cryocooler include a pressure control valve, a valve housing which accommodates the pressure control valve, a motor which includes a motor output shaft, a reduction mechanism which connects the motor output shaft to the pressure control valve in a power transmittable manner, and a magnetic shield case which encloses the motor and is hermetically connected to the valve housing. The motor may include a motor case from which the motor output shaft protrudes. The magnetic shield case may enclose the motor outside the motor case.

An air distribution mechanism and a corresponding cryogenic refrigerator are provided. The air distribution mechanism includes an air distribution valve (6) and a rotary valve (7), the air distribution valve (6) includes an air distribution valve main body (6a) and an air distribution valve seat (6b), an air distribution plane (6a3) that is on the air distribution valve main body (6a) and faces away from the air distribution valve seat (6b) protrudes relative to the air distribution valve seat (6b), the air distribution plane (6a3) is tightly attached to a switching plane (73) on the rotary valve (7), and the switching plane (73) protrudes from the rotary valve (7); the air distribution valve (6) is fixedly mounted in a mounting chamber of a cover (2), and the rotary valve (7) is rotatable around a principal rotation axis O of the rotary valve relative to the air distribution valve (6) to switch connection states of an air distribution side flow path and a switching side flow path. The cryogenic refrigerator includes the air distribution mechanism. The air distribution mechanism can avoid performing surface treatment on the rotary valve 7 to reduce costs, and only the rotary valve 7 is a moving component, to ensure the device stability.

A self-pressure-relief air distribution mechanism includes an air distribution valve (6) where a rear face of the air distribution valve (6) is divided into a high-pressure face (66) and a low-pressure face (65), each hermetically separated by a third sealing ring (b3) that seals the air distribution valve (6) and a cover (2). A low-pressure passage (22) of the cover (2) can communicate with the rear face of the air distribution valve (6) via a pressure-relief hole (61), to guide a low-pressure airflow in the cover (2) to the rear face of the air distribution valve (6). A cryogenic refrigerator includes the self-pressure-relief air distribution mechanism. With the provision of the pressure-relief hole (61) and the third sealing ring (b3), the self-pressure-relief air distribution mechanism has a reduced pressure receiving area, thereby reducing a positive acting force and reducing wear.

Apparatus for controlling a cryogenic cooling system is described. A supply gas line (3A) and a return gas line (3B) are provided which are coupled to a compressor (1) and to a mechanical refrigerator (2) via a coupling element (4). The coupling element is in gaseous communication with the supply (2A) and return gas lines and supplies gas to the mechanical refrigerator (2). The pressure of the supplied gas is modulated by the coupling element in a cyclical manner. A pressure sensing apparatus (6) monitors the pressure in at least one of the supply and return gas lines. A control system (5) is used to modulate the frequency of the cyclical gas pressure supplied by the coupling element in accordance with the pressure monitored by the pressure sensing apparatus. An associated method of controlling such a system is also described.

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 housing internally defining a low-pressure gas chamber; a valve stator defining a variable pressure zone and a high-pressure zone between the housing and the valve stator; a valve rotor, a first seal member disposed adjacent to the high-pressure zone to seal the high-pressure zone and encompassing a first surface area; a second seal member disposed adjacent to the variable pressure zone to seal the variable pressure zone, and encompassing a second surface area that is larger than the first surface area; and a third seal member disposed adjacent to the variable pressure zone to seal the variable pressure zone, and encompassing a third surface area that is larger than the second surface area.

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 GM cryocooler includes a valve portion which defines a valve group including a first intake valve, a first exhaust valve, and a pressure equalizing valve. A valve rotor of the valve portion includes a rotor plane which is in surface contact with a stator plane of a valve stator. The valve rotor includes a high pressure flow path which is open to the rotor plane to form a portion of the first intake valve, a low pressure flow path which is open to the rotor plane to form a portion of the first exhaust valve, and a pressure equalization flow path which is open to the rotor plane to form a portion of the pressure equalizing valve, and the high pressure flow path, the low pressure flow path, and the pressure equalization flow path are circumferentially arranged around a valve rotation axis on the rotor plane.

A connecting device in a pulse tube cooler system branches such that a first line branch (11) has a first flexible line segment (4a) and a second line branch (12) has a second flexible line segment (4b), the flexible line segments being arranged in parallel with and offset from one another. The flexible line segments each have a front segment end (17, 18) and a rear segment end (19, 20), the front segment end (17) of the first flexible line segment (4a) and the rear segment end (20) of the second flexible line segment (4b) are rigidly connected to one another, the rear segment end (19) of the first flexible line segment (4a) and the front segment end (18) of the second flexible line segment (4b) are rigidly connected to one another, and there is no continuous rigid connection between the control valve and the cold head.

A cryocooler include a pressure control valve, a valve housing which accommodates the pressure control valve, a motor which includes a motor output shaft, a reduction mechanism which connects the motor output shaft to the pressure control valve in a power transmittable manner, and a magnetic shield case which encloses the motor and is hermetically connected to the valve housing. The motor may include a motor case from which the motor output shaft protrudes. The magnetic shield case may enclose the motor outside the motor case.