Helix Technology Corporation

Graham J Higham

Gerald R Pruitt

Ronald N Morris

James Livingstone

Niels O Young

Alan L Weeks

Harry G Nicoll

Steven A Michaud

David Tormey

William Sand

Frank Heger

Howard D Snively

A linear drive motor of a cryogenic refrigerator, where a reciprocating armature is coupled to a piston which alternately compresses and expands a gaseous fluid in a thermodynamic cycle. The piston has a clearance seal and is attached at one end to a flexible coupling to reduce cross-bearing loads exerted by the piston along the clearance seal. A displacer assembly of the cryogenic refrigerator employs a displacer piston that reciprocates along a clearance seal. The displacer piston is coupled to the displacer cylinder and/or the armature of a displacer drive motor by a flexible coupling that reduces radial forces exerted by the displacer piston on the clearance seal.

Linear drive motor with flexible coupling

A linear drive motor of a cryogenic refrigerator, where a reciprocating armature (10) which alternately compresses and expands a gaseous fluid in a thermodynamic cycle, is supported at both ends by flexure supports (110, 130). The armature has a clearance seal (150) with a stationary piston (11) attached at one end to the armature housing by a flexible stem (11B) to minimize cross-bearing loads between the armature and the stationary piston along the clearance seal.

Linear drive motor with flexure bearing support

In a cryogenic refrigeration utilizing a linear drive motor, a temperature control system controls the displacement of an armature reciprocating at a fixed frequency to adjust the operating temperature of a working fluid at the cold end of a cold finger. Linear drive motors using dynamic absorbers to reduce vibration operate within the narrow frequency range to which the absorber is tuned. Controlling the maximum displacement of the armature used to compress the working fluid results in the ability to adjust the temperature at the cold end of the refrigeration without altering the frequency of operation.

Temperature control system for a cryogenic refrigeration

A linear motor compressor within a cryogenic refrigerator wherein the compressor space, within which a gaseous fluid is alternately compressed and expanded, is formed by a stationary piston and a reciprocating armature that is concentric about the piston. The armature is supported along a clearance seal the stationary piston. An axial bore along the stationary piston conveys gaseous fluid from the compression space to a displacer within the cold finger of the cryogenic refrigerator. An isolator for reducing transimission into and out of the compressor comprising a dynamic absorber and flat springs mounted with a damping material between the compressor and a mounting frame. A sensor for detecting the position of the armature utilizes a target magnet whose magnetic flux lines are decoupled from the flux lines generated about the coil.

Linear motor compresser with stationary piston

A two mass vibration isolator particularly suited to a linear reciprocating machine. Vibration into and out of the machine is attenuated by an isolator placed between the machine and its mounting frame. The isolator is an elastomer with a damping ratio of at least 0.1 sandwiched between two retainers.

Vibration isolation system for a linear reciprocating machine

A linear drive motor of cryogenic refrigerator in which a reciprocating armature alternately compresses and expands a gaseous fluid in a thermodynamic cycle. An isolator system comprising a countermass, having an antiphase movement with respect to the armature is centrally mounted on unitary springs. Isolator springs are mounted between the compressor and the compressor housing such that vibrations in to and out of the system are attenuated.

Linear drive motor with improved dynamic absorber

A linear drive motor of a cryogenic refrigerator, where a reciprocating armature which alternately compresses and expands a gaseous fluid in a thermodynamic cycle, is supported at both ends by flexure supports. The armature has a clearance seal with a stationary piston attached at one end to the armature housing by a flexible stem to minimize cross-bearing loads between the armature and the stationary piston along the clearance seal.

In a cryogenic split Stirling refrigerator, the compressor is driven by linear drive motors. Each linear drive motor has an armature hermetically sealed by a housing 20. Surrounding the housing is a stator formed from two bodies each housing a drive coil 48 and 49. Each body consists of two components 52-55 formed from involute laminations which have been aligned after the coil has been inserted. Separating the bodies is a magnet 56.

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Ashland, MA, United States of America

Graham J Higham