Miniaturized gas refrigeration device with two or more thermal regenerator sections
View Patent ↗The size of a miniature cryocooler ( 100 ) operating on the Stirling refrigeration cycle is further reduced by shortening a first thermal regenerator module (R) disposed on a cold side of a thermal barrier (T) and providing a second thermal regenerator module (R 1 ) disposed on a warm side of the thermal barrier (T). A thermally insulated fluid flow passage ( 172 ) is disposed to interconnect the first and second regenerator modules to thermally insulate the fluid passage ( 172 ). In combination, the first and second regenerator modules provide 100% thermal regenerator effectiveness in the device.
1. A refrigeration device comprising:
a crankcase;
a compression cylinder disposed within the crankcase and ending in a cylinder head;
a compression piston movably disposed within the compression cylinder, the compression piston separated from the cylinder head by a compression volume and dimensioned with a gas sealing fit with respect to the compression cylinder to prevent pressurized gas from escaping from the compression volume into the crankcase;
a cold finger tube extending from the crankcase;
an expansion cylinder disposed within the crankcase and extending to the cold finger tube, the expansion cylinder including a first fluid port in fluid communication with the compression volume through a fluid conduit extending from the cylinder head to the first fluid port;
a gas displacing piston comprising a fluid control portion disposed in the expansion cylinder and a regenerator tube located in the cold finger tube, the fluid control portion including annular bearing surfaces configured to provide a gas seal between the fluid control portion and the expansion cylinder;
a first regenerator matrix disposed entirely within the regenerator tube and characterized by a first diameter; and
a second regenerator matrix disposed entirely within a thermally insulated cavity of the fluid control portion and characterized by a second diameter smaller than the first diameter;
wherein the second regenerator matrix is physically separated from the first regenerator matrix by a thermal barrier and a first fluid passage extending between the first regenerator matrix and the second regenerator matrix; and
wherein the fluid control portion includes a second fluid passage extending between the second regenerator matrix towards the first fluid port.
2. The refrigeration device of claim 1 wherein: said regenerator tube includes a porous end cap attached to a distal end of the regenerator tube for holding the first regenerator matrix within the regenerator tube.
3. The refrigeration device of claim 1 wherein:
the thermal barrier comprises annular insulating disks forming the first fluid passage; and
the first fluid passage comprises a single fluid aperture.
4. The refrigeration device of claim 1 , wherein a local ambient temperature for the crankcase ranges from about 220° K. to about 320° K.
5. The refrigeration device of claim 1 , wherein a cold temperature for a distal end of the cold finger tube is substantially less than the local ambient temperature.
6. The refrigeration device of claim 5 , wherein the cold temperature is in a cryogenic range.