Linear drive motor with flexible coupling

A dual piston linear drive motor comprising:

• a first piston and a second piston reciprocating within a cylinder to define a compression space there between in which a fluid is compressed and expanded;
• a first magnetic armature coupled to the first piston by a first flexible piston coupling and a second magnetic armature coupled to the second piston by a second flexible piston coupling such that each piston coupling bends to reduce radial forces exerted by the first and second pistons on clearance seals located between the cylinder and the first and second pistons;
• a first coil assembly surrounding the first armature to drive the first armature;
• and
• a second coil assembly surrounding the second armature to drive the second armature.

A cryogenic refrigerator having a gaseous working fluid which is alternately compressed and expanded to cool a portion of the working fluid to cryogenic temperatures, the refrigerator comprising:

• a compressor housing that seals the working fluid within a volume;
• a first piston and a second piston reciprocating within a cylinder to define a compression space there between in which a fluid is compressed and expanded;
• a first magnetic armature coupled to the first piston by a first flexible piston coupling and a second magnetic armature coupled to the second piston by a second flexible piston coupling such that each piston coupling bends to reduce radial forces exerted by the first and second pistons on clearance seals located between the cylinder and the first and second pistons
• a first coil assembly surrounding the first armature to drive the first armature;
• a second coil assembly surrounding the second armature to drive the second armature;
• a gas displacer within a cold finger of the refrigerator and having a displacer volume in fluid communication with the compressor volume and comprising a displacer piston reciprocating along an axis, the displacer piston being coupled to a displacer by a third flexible piston coupling that provides for universal radial displacement of the coupling relative to the axis.

A gas displacer for a refrigerator in which the gas displacer reciprocates in a housing to displace gas in a working volume of pressurized gas through a regenerator, the gas displacer comprising:

• a working volume within a housing of the gas displacer through which the pressurized gas flows;
• a displacer reciprocating within an expander cylinder, the displacer having a regenerative matrix to absorb heat from the gas;
• and
• a flexible coupling that is coupled to the displacer at one end, and to a reciprocating element at the opposite end, the flexible coupling reciprocating along a longitudinal axis of the gas displacer and providing for universal radial displacement of the coupling relative to the axis.

A linear drive motor for a cryogenic refrigerator in which a gaseous working fluid is alternately compressed and expanded to cool a portion of the working fluid to cryogenic temperatures, the refrigerator comprising:

• a housing that seals the working fluid within a volume;
• a piston positioned within the housing along a longitudinal axis thereof, the piston forming a clearance seal with, and having a linear reciprocating motion relative to, a clearance seal element;
• a magnetic armature secured to the piston, the armature reciprocating concentrically within a coil assembly that surrounds the housing;
• and
• a sleeve support bearing positioned between an outer cylindrical surface of the armature and an inner cylindrical surface of the housing such that the sleeve support bearing supports the armature during its reciprocating movement relative to the housing.