The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 09, 2004
Filed:
Apr. 07, 2004
Gerald David Duncan, Auckland, NZ;
John Henry Boyd, Holland, MI (US);
Fisher & Paykel Limited, Auckland, NZ;
Abstract
An electric linear motor for driving a reciprocating load includes a stator, a coil, an armature and a commutation circuit. The stator has a magnetically permeable core with an air gap. The coil is wound around a portion of the stator and energized with a non-constant voltage for producing a non-constant magnetic flux in the stator and the air gap. The armature supports a permanent magnet having a substantial portion located in the air gap. The interaction of the magnetic field of the magnet and the non-constant flux in the air gap produces a force on the armature. The armature is connected to the load and reciprocates with respect to the stator. The circuit controls the coil such that at least one end of the magnet passes outside the region of substantially uniform flux density within the air gap during a portion of the motion of the armature.