A cryocooler includes a compressor, an expander that includes a motor and is driven by the motor, an inverter that controls an operation frequency of the motor, a high pressure line that connects the compressor to the expander such that a working gas is supplied from the compressor to the expander, a low pressure line that connects the compressor to the expander such that a working gas is collected from the expander to the compressor, a pressure measurement unit that is configured to measure pressures of the high pressure line and the low pressure line or to measure a differential pressure between the high pressure line and the low pressure line, and a controller that compares the differential pressure to a target pressure and controls the inverter such that the operation frequency of the motor is increased when the differential pressure exceeds the target pressure.

A cryocooler includes a cold head including a displacer movable in an axial direction, a drive piston connected to the displacer to move the displacer in the axial direction, an expansion chamber formed with the displacer, a piston drive chamber formed with the drive piston, a spool valve including a valve drive chamber, a spool that moves between a first position and a second position in response to a pressure of the valve drive chamber, and a pressure control mechanism configured to control a pressure of the valve drive chamber so that the spool reciprocates between the first position and the second position, and to generate a pressure fluctuation having an opposite phase to the pressure fluctuation in the expansion chamber in the piston drive chamber in synchronization with the reciprocation of the spool.

A pulse tube cryocooler is furnished with a second-stage cooling stage and an insert. The second-stage cooling stage has a lateral-surface opening, and a first heat-exchange surface extending in a sideways direction from the lateral-surface opening into the second-stage cooling stage. The insert includes a base-end portion fixedly fitted into the second-stage cooling stage to plug the lateral-surface opening, and a second heat-exchange surface that extends in the sideways direction from the base-end portion and is disposed inside the second-stage cooling stage, opposing the first heat-exchange surface. Between the first heat-exchange surface and the second heat-exchange surface the insert forms a clearance that flows a working gas, bringing both the first heat-exchange surface and the second heat-exchange surface into contact with the working gas.

The disclosed subject matter includes an active control alternating-direct flow hybrid mechanical cryogenic system, and relates to the field of cryogenic refrigeration technologies. The active control alternating-direct flow hybrid mechanical cryogenic system includes a main compressor, a Stirling cold finger, an intermediate heat exchanger, a pulse tube cold finger, a first dividing wall type heat exchanger, a final precooled heat exchanger, a second dividing wall type heat exchanger, and an evaporator that are communicated successively, where the second dividing wall type heat exchanger is connected to the evaporator through a second connecting pipeline, and a throttling element is disposed on the second connecting pipeline; a pulse tube cold head of the pulse tube cold finger is communicated with the final precooled heat exchanger through a cold chain; and a check valve is disposed on the intermediate heat exchanger.

A cryocooler includes a compressor, an expander, a gas line that allows a working gas to be circulated between the compressor and the expander and includes a high pressure line through which the working gas is supplied from the compressor to the expander and a low pressure line through which the working gas is collected from the expander to the compressor, a bypass line that connects the high pressure line to the low pressure line such that the working gas bypasses the expander and returns from the high pressure line to the low pressure line, and a bypass flow rate control unit that controls a flow rate of the working gas flowing in the bypass line to provide pressure control of the gas line. The bypass line includes a variable flow rate bypass and a fixed flow rate bypass.

A refrigerator includes a regenerator, a low-temperature end heat exchanger, a pulse tube, a high-temperature end heat exchanger, and a phase adjustment mechanism, connected in that order. A draft tube is provided inside the regenerator, paralleling the regenerator's axis, and the draft tube can extend into the low-temperature end heat exchanger.

A pulse tube cryocooler includes: a pulse tube having a pulse tube high-temperature end and a pulse tube low-temperature end, and extending in an axial direction from the pulse tube high-temperature end to the pulse tube low-temperature end; a regenerator having a regenerator high-temperature end and a regenerator low-temperature end, and being disposed rowed alongside the pulse tube, with the regenerator high-temperature end being positioned displaced, in terms of the axial direction, from the pulse tube high-temperature end toward the cryocooler low-temperature side, and the regenerator low-temperature end being fluid-passage linked with the pulse tube low-temperature end; and a pressure-switching valve for connecting the regenerator high-temperature end to a high-pressure source and to a low-pressure source in alternation, and being disposed between the pulse tube high-temperature end and the regenerator high-temperature end in terms of the axial direction.

A pulse tube cryocooler is furnished with a second-stage cooling stage and an insert. The second-stage cooling stage has a lateral-surface opening, and a first heat-exchange surface extending in a sideways direction from the lateral-surface opening into the second-stage cooling stage. The insert includes a base-end portion fixedly fitted into the second-stage cooling stage to plug the lateral-surface opening, and a second heat-exchange surface that extends in the sideways direction from the base-end portion and is disposed inside the second-stage cooling stage, opposing the first heat-exchange surface. Between the first heat-exchange surface and the second heat-exchange surface the insert forms a clearance that flows a working gas, bringing both the first heat-exchange surface and the second heat-exchange surface into contact with the working gas.

A gas wave refrigerator including a first end body; a second end body; a main body disposed between the first end body and the second end body; a first end cover; a hydraulic mandrel; a hydraulic oil inlet pipe; a hydraulic cylinder; a first single mechanical seal; a bushing; a nozzle rotator including two rows of nozzles; press plates disposed at two sides of the nozzle rotator; a main shaft; oscillation receiving tubes; a belt wheel; an embedded bearing seat; a second end cover; and a hydraulic balance device. The hydraulic balance device includes a hydraulic cylinder, a hydraulic mandrel, a seal ring, bearings, a piston, and a piston ring. The nozzle rotator and the press plates disposed at two sides of the nozzle rotator are installed on the main shaft.

A pulse tube cryocooler includes a cold head including a pulse tube and a radiator thermally coupled to a high-temperature end of the pulse tube, and a forced cooler that forcedly cools the radiator in a cool-down operation of the pulse tube cryocooler from an ambient temperature to a cryogenic temperature.