Cryogenic refrigerator

Abstract

A cryogenic refrigerator includes a first cylinder and a second cylinder, a first displacer and a second displacer configured to reciprocate inside the first cylinder and the second cylinder, respectively, an intake and outlet system configured to alternately perform a first operation of supplying gas to the first cylinder and discharging the gas from the second cylinder and a second operation of discharging the gas from the first cylinder and supplying the gas to the second cylinder, a communication path configured to communicate the first cylinder with the second cylinder, and an opening and closing part configured to open and close the communication path.

What is claimed is: 
     
         1 . A cryogenic refrigerator, comprising:
 a first cylinder and a second cylinder;   a first displacer and a second displacer configured to reciprocate inside the first cylinder and the second cylinder, respectively;   an intake and outlet system configured to alternately perform a first operation of supplying gas to the first cylinder and discharging the gas from the second cylinder and a second operation of discharging the gas from the first cylinder and supplying the gas to the second cylinder;   a communication path configured to communicate the first cylinder with the second cylinder; and   an opening and closing part configured to open and close the communication path.   
     
     
         2 . The cryogenic refrigerator as claimed in  claim 1 , wherein the opening and closing part is configured to open the communication path for a predetermined period of time immediately before each of the first operation and the second operation of the intake and outlet system. 
     
     
         3 . The cryogenic refrigerator as claimed in  claim 1 , further comprising:
 a drive mechanism configured to drive the first displacer and the second displacer in different phases; and   a drive part configured to drive the drive mechanism.   
     
     
         4 . The cryogenic refrigerator as claimed in  claim 3 , wherein the drive mechanism further includes a connection mechanism configured to connect the first displacer and the second displacer. 
     
     
         5 . The cryogenic refrigerator as claimed in  claim 4 , wherein the connection mechanism includes
 a support member extending from a lid part provided on the first and second cylinders placed side by side; and   an arm part having a center portion rotatably connected to the support member, having a first end portion rotatably connected to a first shaft extending from the first displacer, and having a second end portion rotatably connected to a second shaft extending from the second displacer.   
     
     
         6 . The cryogenic refrigerator as claimed in  claim 5 , wherein the drive mechanism further includes a Scotch yoke mechanism configured to convert a rotational driving force of the drive part into a reciprocative driving force, the Scotch yoke mechanism forming a part of the first shaft. 
     
     
         7 . The cryogenic refrigerator as claimed in  claim 6 , wherein the connection mechanism further includes an additional arm part having a first end portion, a second end portion, and a center portion rotatably connected to the first shaft, the second shaft, and the support member, respectively, so as to be parallel to the arm part. 
     
     
         8 . The cryogenic refrigerator as claimed in  claim 1 , further comprising:
 in addition to a pair of the first displacer and the second displacer, one or more pairs of the first displacer and the second displacer.   
     
     
         9 . The cryogenic refrigerator as claimed in  claim 1 , further comprising:
 a cooling stage thermally coupled to the first cylinder and the second cylinder.   
     
     
         10 . The cryogenic refrigerator as claimed in  claim 9 , wherein the cooling stage is coupled to respective peripheries of the first cylinder and the second cylinder so as to surround a first expansion space formed between a low temperature end of the first displacer and the first cylinder and a second expansion space formed between a low temperature end of the second displacer and the second cylinder.