Regenerative refrigerator

Abstract

A regenerative refrigerator includes a compressor compressing working fluid; a cylinder fed with the compressed working fluid, containing a regenerator material, and having an expansion space; and a rotary valve to switch a first passage and a second passage formed to cause the working fluid to flow from the compressor to the expansion space and from the expansion space to the compressor, respectively. The working fluid expands in the expansion space to generate cold temperatures in the cylinder. The rotary valve includes a valve body having a first flat surface; and a valve plate having a second flat surface and configured to rotate with the first and second flat surfaces in surface contact. One of the first and second flat surfaces has an arithmetic average roughness of 0.1 μm to 0.9 μm. The other one of the first and second flat surfaces includes resin.

What is claimed is: 
     
         1 . A regenerative refrigerator, comprising:
 a compressor configured to compress a working fluid;   a cylinder configured to be fed with the compressed working fluid, the cylinder containing a regenerator material and having an expansion space provided at one end thereof; and   a rotary valve provided between the compressor and the cylinder, the rotary valve being configured to switch a first passage and a second passage, the first passage being formed to cause the working fluid to flow from the compressor to the expansion space, the second passage being formed to cause the working fluid to flow from the expansion space to the compressor,   wherein the working fluid expands in the expansion space to generate cold temperatures in the cylinder,   the rotary valve includes a valve body having a first flat surface; and a valve plate having a second flat surface, the valve plate being configured to rotate with the first flat surface and the second flat surface in surface contact, and   a first one of the first flat surface and the second flat surface has an arithmetic average roughness of 0.1 μm to 0.9 μm, and a second one of the first flat surface and the second flat surface includes a resin.   
     
     
         2 . The regenerative refrigerator as claimed in  claim 1 , wherein the first one of the first flat surface and the second flat surface includes a metal-doped carbon film. 
     
     
         3 . The regenerative refrigerator as claimed in  claim 2 , wherein the first one of the first flat surface and the second flat surface includes one of an aluminum metal and an aluminum alloy as a base material. 
     
     
         4 . The regenerative refrigerator as claimed in  claim 3 , wherein the first one of the first flat surface and the second flat surface is anodized. 
     
     
         5 . The regenerative refrigerator as claimed in  claim 2 , wherein the metal-doped carbon film includes at least one selected from the group consisting of chromium, titanium, tungsten, silicon, and molybdenum. 
     
     
         6 . The regenerative refrigerator as claimed in  claim 2 , wherein the first one of the first flat surface and the second flat surface further includes at least one of a nickel film, a chromium film, and a chromium nitride film under the metal-doped carbon film. 
     
     
         7 . The regenerative refrigerator as claimed in  claim 1 , wherein the first one of the first flat surface and the second flat surface further includes one of an aluminum metal and an aluminum alloy as a base material. 
     
     
         8 . The regenerative refrigerator as claimed in  claim 7 , wherein the first one of the first flat surface and the second flat surface is anodized. 
     
     
         9 . The regenerative refrigerator as claimed in  claim 1 , wherein the resin includes at least one of polyether sulfone, wholly aromatic polyester, and polytetrafluoroethylene. 
     
     
         10 . The regenerative refrigerator as claimed in  claim 1 , wherein the regenerative refrigerator is one of a Gifford-McMahon refrigerator, a pulse tube refrigerator, and a Solvay refrigerator.