Fluidic 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 controlled in part through the introduction of high-pressure fluid, 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 piston coupled to said slide intermediate its ends for controlling movement of the displacer, means for cycling gas at a metered rate between opposite faces of said piston when said displacer moves, 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.