Abstract: An improved cryogenic refrigerator having a drive mechanism suitable for use with gap or clearance seals is disclosed. The drive mechanism includes two reciprocating members, e.g. piston and regenerator/displacer, driven by a common rotating drive shaft. The regenerator/displacer portion of the drive shaft includes a roller at one end in engagement with a rod base plate for driving a rod connected to the regenerator/displacer and a spring for returning the regenerator/displacer simultaneously with the withdrawal of the drive shaft. The piston portion of the drive shaft is connected to a first end of a hollow body. The second end of the hollow body which is opposite the first end has the piston rigidly affixed thereto. The hollow body has a portion adjacent the first end supported by a guide whereby the piston is substantially isolated from side force loads during reciprocation.

Abstract: An improved Vuilleumier cycle refrigerator is disclosed. To reduce fluid contamination and inactive refrigerant volume, the hot and cold fluid displacers of the refrigerator are driven by a magnetic drive mechanism. The magnetic drive mechanism has a first and second assembly. The first assembly is contained in the fluid chamber together with the hot and cold displacers; the second assembly including the drive motor is mounted exteriorly of the fluid chamber. The first and second assemblies of the drive mechanism include adjacent magnets separated by the wall of the fluid chamber. Thus, the first and second assemblies are coupled together by their magnetic field for rotation to drive the hot and cold displacers and the fluid chamber provides an hermetic seal to contain the working fluid thereby removing the motor with its air space and contaminants from the fluid chamber.