Patent ID: 6256997
Filing Date: 2001-07-10
Classification: F25B

Abstract:
An expander of a GM type for use in providing cryogenic refrigeration, comprising:a cylinder serving as at least one cold head, said cylinder having a longitudinal axis;a displacer assembly extending axially within said cylinder between a cold zone of said cylinder and a warm zone, said displacer being reciprocatably moveable axially in said cylinder between a first stroke end position and a second stroke end position;first mechanical means fixed relative to one of said cylinder and said displacer assembly for stopping said reciprocating motion of said displacer assembly in a first axial direction, said displacer assembly stopping at said first end position;second mechanical means fixed relative to one of said cylinder and displacer assembly for stopping said reciprocating motion of said displacer assembly in a second axial direction at said second end position;said first mechanical means including a first impact absorber connecting between said cylinder and displacer assembly when said displacer assembly is at said first end position;said second mechanical means including a second impact absorber connecting between said cylinder and said displacer assembly when said displacer assembly is at said second end position;said first and second absorbers being located closer to said first end position than to said second end position.