Bumper retainer for cryogenic expander systems

A cryogenic expander system for providing reduced noises and vibrations, the cryogenic expander comprising:

• a cylinder having a warm cylinder end and a cold cylinder end;
• a displacer disposed in the cylinder, the displacer having a warm displacer end and a cold displacer end, the displacer reciprocating between the warm cylinder end and the cold cylinder end;
• a cylinder head disposed on the cylinder, wherein the cylinder head comprises a neck and a wall surrounding the neck, providing an internal space between the neck and the wall, wherein the neck and the warm displacer end provide a warm displaced volume in the cylinder between the neck and the warm displacer end;
• a collar integrated to the warm displacer end and extending upward from the warm displace end, wherein the collar is disposed in the internal space between the neck and the wall, wherein either:
• (i) the collar includes a first lip at a top portion of the collar protruding toward the wall and a second lip at a bottom portion of the collar protruding toward the wall, providing a recessed space between the first and second lips, and the wall has a groove on a side of the wall facing the neck,
• (ii) the wall has a recessed space on a side of the wall facing the neck defined by a first lip and second lip of the wall, and the collar has a groove on a side of the collar facing the wall,
• (iii) the neck has a recessed space on a side of the neck facing the wall defined by a first lip and second lip of the neck, and the collar has a groove on a side of the collar facing the neck, or (iv) the collar includes a first lip at a top portion of the collar protruding toward the neck and a second lip at a bottom portion of the collar protruding toward the neck, providing a recessed space between the first and second lips, and the neck has a groove on a side of the neck facing the wall;
• a bumper retainer assembly disposed in the groove and comprising at least one bumper ring and at least one bumper retainer to place the at least one bumper ring, wherein an end portion of the at least one bumper retainer projects into the recessed space.