Stirling cryocooler

Abstract

In a Stirling cryocooler, a displacer includes an internal space which is filled with gas. The displacer is reciprocatably accommodated in the expander main body. The displacer accommodates in the internal space one or more convection control plates, for controlling gas convection to a minimum. The one or more convection control plates are disposed along a line intersecting the displacer's longitudinal axis. At least one of the convection control plates divides the internal space into first and second sub-chambers, and includes an opening through which the sub-chambers communicate. The at least one of the convection control plates includes a convection control wall provided in the opening.

What is claimed is: 
     
         1 . A Stirling cryocooler comprising:
 a displacer having a longitudinally extending gas-filled internal space;   an expander main body reciprocatably accommodating the displacer; and   at least one convection control plate for controlling gas convection to a minimum, accommodated in the displacer internal space, disposed along a line intersecting the displacer's longitudinal axis; wherein   the at least one convection control plate divides the displacer internal space into first and second sub-chambers, includes an opening through which the first sub-chamber communicates with the second sub-chamber, and includes a convection control wall provided on the opening.   
     
     
         2 . The Stirling cryocooler according to  claim 1 , further comprising:
 a regenerator contained in the expander main body such as to be located outer peripherally along the displacer, in a predetermined cylindrical region having the longitudinal axis of the displacer as its center axis, wherein the at least one convection control plate is provided such as to be positioned, even when the displacer reciprocates, in a location corresponding to the predetermined cylindrical region in which the regenerator is positioned.   
     
     
         3 . The Stirling cryocooler according to  claim 1 , wherein the displacer accommodates a plurality of the convection control plates. 
     
     
         4 . The Stirling cryocooler according to  claim 1 , wherein the at least one convection control plate is in thermal contact with an inner wall of the displacer. 
     
     
         5 . The Stirling cryocooler according to  claim 1 , wherein:
 the displacer further includes a gas-convection minimizing filling member; and   the at least one convection control plate retains the filling member.   
     
     
         6 . The Stirling cryocooler according to  claim 5 , wherein the filling member is composed of a synthetic resin polymer. 
     
     
         7 . The Stirling cryocooler according to  claim 5 , wherein the filling member is either fibrous or reticular. 
     
     
         8 . The Stirling cryocooler according to  claim 1 , wherein:
 the expander main body is configured to form an expansion space between the displacer and the expander main body, and to form a compression space between the displacer and the expander main body on a side thereof longitudinally opposite from the expansion space in the axial orientation of the displacer; and   the displacer in its internal space accommodates a plurality of the convection control plates, densely arranged on the expansion-space side of the displacer and sparsely arranged on the compression-space side of the displacer along its longitudinal axis.   
     
     
         9 . The Stirling cryocooler according to  claim 1 , comprising at least two of the convection control plates, each having a sub-chamber communicating opening, wherein the sub-chamber communicating openings of adjacent convection control plates are displaced relative to each other in a plane intersecting the longitudinal axis of the displacer. 
     
     
         10 . The Stirling cryocooler according to  claim 1 , wherein the convection control wall extends outer peripherally from the opening in at least one sideward direction along the longitudinal axis of the displacer.