Cryogenic refrigerator

A cryogenic refrigerator comprising a movable displacer within an enclosure having first and second chambers of variable volume and in which a refrigerant fluid is circulated in a fluid flow path between said first chamber and said second chamber by the movement of said displacer, chamber means for guiding a slide connected to the displacer, said slide having an axial passage communicating with one end of said chamber means remote from the displacer and said first chamber, an electrical motor coupled to said slide intermediate its ends for controlling movement of the displacer at top dead center and bottom dead positions thereof, said passage in said slide having a restriction, a valve having a spool valve member for controlling flow the high and low pressure fluid, means including a conduit communicating one end of said spool valve member with said one end of said chamber means for introducing high pressure fluid into the conduit to shift the spool valve member when the displacer is at bottom dead center, said spool valve member having an axial passage containing a restriction therein adjacent the end thereof communicating with the conduit.

A cryogenic refrigerator system comprising a movable displacer within an enclosure having first and second chambers of variable volume and in which a refrigerant fluid is circulated in a fluid flow path between said first chamber and said second chamber by the movement of said displacer, a heat station at one of said chambers for transmitting a low temperature, chamber means for guiding a slide connected to the displacer, said slide having an axial passage communicating with one end of said chamber means remote from the displacer and said first chamber, a motor coupled to said slide for controlling movement of the displacer, said passage in said slide having a restriction, a valve having a fluid pressure responsive valve member for controlling flow the high and low pressure fluid to the displacer, means including a conduit communicating one end of said spool valve member with said one end of said chamber means for introducing high pressure fluid into the conduit to shift the spool valve member when the displacer is at one end of its stroke, a pilot valve controlling flow between said valve member and chamber means for reversing operation so that high pressure fluid is introduced into said conduit when said displacer is at the opposite end of its stroke, said pilot valve being responsive to the temperature in a cryopump cooled by said heat station.